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10 <title>core - Apache HTTP Server Version 2.5</title>
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20 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
21 <p class="apache">Apache HTTP Server Version 2.5</p>
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25 <a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.5</a> > <a href="./">Modules</a></div>
26 <div id="page-content">
27 <div id="preamble"><h1>Apache Core Features</h1>
29 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
30 <a href="../en/mod/core.html" title="English"> en </a> |
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36 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Core Apache HTTP Server features that are always
38 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Core</td></tr></table>
40 <div id="quickview"><h3 class="directives">Directives</h3>
42 <li><img alt="" src="../images/down.gif" /> <a href="#acceptfilter">AcceptFilter</a></li>
43 <li><img alt="" src="../images/down.gif" /> <a href="#acceptpathinfo">AcceptPathInfo</a></li>
44 <li><img alt="" src="../images/down.gif" /> <a href="#accessfilename">AccessFileName</a></li>
45 <li><img alt="" src="../images/down.gif" /> <a href="#adddefaultcharset">AddDefaultCharset</a></li>
46 <li><img alt="" src="../images/down.gif" /> <a href="#allowencodedslashes">AllowEncodedSlashes</a></li>
47 <li><img alt="" src="../images/down.gif" /> <a href="#allowoverride">AllowOverride</a></li>
48 <li><img alt="" src="../images/down.gif" /> <a href="#allowoverridelist">AllowOverrideList</a></li>
49 <li><img alt="" src="../images/down.gif" /> <a href="#asyncfilter">AsyncFilter</a></li>
50 <li><img alt="" src="../images/down.gif" /> <a href="#cgimapextension">CGIMapExtension</a></li>
51 <li><img alt="" src="../images/down.gif" /> <a href="#cgipassauth">CGIPassAuth</a></li>
52 <li><img alt="" src="../images/down.gif" /> <a href="#cgivar">CGIVar</a></li>
53 <li><img alt="" src="../images/down.gif" /> <a href="#contentdigest">ContentDigest</a></li>
54 <li><img alt="" src="../images/down.gif" /> <a href="#defaultruntimedir">DefaultRuntimeDir</a></li>
55 <li><img alt="" src="../images/down.gif" /> <a href="#defaulttype">DefaultType</a></li>
56 <li><img alt="" src="../images/down.gif" /> <a href="#define">Define</a></li>
57 <li><img alt="" src="../images/down.gif" /> <a href="#directory"><Directory></a></li>
58 <li><img alt="" src="../images/down.gif" /> <a href="#directorymatch"><DirectoryMatch></a></li>
59 <li><img alt="" src="../images/down.gif" /> <a href="#documentroot">DocumentRoot</a></li>
60 <li><img alt="" src="../images/down.gif" /> <a href="#else"><Else></a></li>
61 <li><img alt="" src="../images/down.gif" /> <a href="#elseif"><ElseIf></a></li>
62 <li><img alt="" src="../images/down.gif" /> <a href="#enablemmap">EnableMMAP</a></li>
63 <li><img alt="" src="../images/down.gif" /> <a href="#enablesendfile">EnableSendfile</a></li>
64 <li><img alt="" src="../images/down.gif" /> <a href="#error">Error</a></li>
65 <li><img alt="" src="../images/down.gif" /> <a href="#errordocument">ErrorDocument</a></li>
66 <li><img alt="" src="../images/down.gif" /> <a href="#errorlog">ErrorLog</a></li>
67 <li><img alt="" src="../images/down.gif" /> <a href="#errorlogformat">ErrorLogFormat</a></li>
68 <li><img alt="" src="../images/down.gif" /> <a href="#extendedstatus">ExtendedStatus</a></li>
69 <li><img alt="" src="../images/down.gif" /> <a href="#fileetag">FileETag</a></li>
70 <li><img alt="" src="../images/down.gif" /> <a href="#files"><Files></a></li>
71 <li><img alt="" src="../images/down.gif" /> <a href="#filesmatch"><FilesMatch></a></li>
72 <li><img alt="" src="../images/down.gif" /> <a href="#forcetype">ForceType</a></li>
73 <li><img alt="" src="../images/down.gif" /> <a href="#gprofdir">GprofDir</a></li>
74 <li><img alt="" src="../images/down.gif" /> <a href="#hostnamelookups">HostnameLookups</a></li>
75 <li><img alt="" src="../images/down.gif" /> <a href="#httpprotocoloptions">HttpProtocolOptions</a></li>
76 <li><img alt="" src="../images/down.gif" /> <a href="#if"><If></a></li>
77 <li><img alt="" src="../images/down.gif" /> <a href="#ifdefine"><IfDefine></a></li>
78 <li><img alt="" src="../images/down.gif" /> <a href="#ifmodule"><IfModule></a></li>
79 <li><img alt="" src="../images/down.gif" /> <a href="#include">Include</a></li>
80 <li><img alt="" src="../images/down.gif" /> <a href="#includeoptional">IncludeOptional</a></li>
81 <li><img alt="" src="../images/down.gif" /> <a href="#keepalive">KeepAlive</a></li>
82 <li><img alt="" src="../images/down.gif" /> <a href="#keepalivetimeout">KeepAliveTimeout</a></li>
83 <li><img alt="" src="../images/down.gif" /> <a href="#limit"><Limit></a></li>
84 <li><img alt="" src="../images/down.gif" /> <a href="#limitexcept"><LimitExcept></a></li>
85 <li><img alt="" src="../images/down.gif" /> <a href="#limitinternalrecursion">LimitInternalRecursion</a></li>
86 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestbody">LimitRequestBody</a></li>
87 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfields">LimitRequestFields</a></li>
88 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfieldsize">LimitRequestFieldSize</a></li>
89 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestline">LimitRequestLine</a></li>
90 <li><img alt="" src="../images/down.gif" /> <a href="#limitxmlrequestbody">LimitXMLRequestBody</a></li>
91 <li><img alt="" src="../images/down.gif" /> <a href="#location"><Location></a></li>
92 <li><img alt="" src="../images/down.gif" /> <a href="#locationmatch"><LocationMatch></a></li>
93 <li><img alt="" src="../images/down.gif" /> <a href="#loglevel">LogLevel</a></li>
94 <li><img alt="" src="../images/down.gif" /> <a href="#logleveloverride">LogLevelOverride</a></li>
95 <li><img alt="" src="../images/down.gif" /> <a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></li>
96 <li><img alt="" src="../images/down.gif" /> <a href="#maxrangeoverlaps">MaxRangeOverlaps</a></li>
97 <li><img alt="" src="../images/down.gif" /> <a href="#maxrangereversals">MaxRangeReversals</a></li>
98 <li><img alt="" src="../images/down.gif" /> <a href="#maxranges">MaxRanges</a></li>
99 <li><img alt="" src="../images/down.gif" /> <a href="#mergetrailers">MergeTrailers</a></li>
100 <li><img alt="" src="../images/down.gif" /> <a href="#mutex">Mutex</a></li>
101 <li><img alt="" src="../images/down.gif" /> <a href="#namevirtualhost">NameVirtualHost</a></li>
102 <li><img alt="" src="../images/down.gif" /> <a href="#options">Options</a></li>
103 <li><img alt="" src="../images/down.gif" /> <a href="#protocol">Protocol</a></li>
104 <li><img alt="" src="../images/down.gif" /> <a href="#protocols">Protocols</a></li>
105 <li><img alt="" src="../images/down.gif" /> <a href="#protocolshonororder">ProtocolsHonorOrder</a></li>
106 <li><img alt="" src="../images/down.gif" /> <a href="#qualifyredirecturl">QualifyRedirectURL</a></li>
107 <li><img alt="" src="../images/down.gif" /> <a href="#registerhttpmethod">RegisterHttpMethod</a></li>
108 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitcpu">RLimitCPU</a></li>
109 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitmem">RLimitMEM</a></li>
110 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitnproc">RLimitNPROC</a></li>
111 <li><img alt="" src="../images/down.gif" /> <a href="#scriptinterpretersource">ScriptInterpreterSource</a></li>
112 <li><img alt="" src="../images/down.gif" /> <a href="#seerequesttail">SeeRequestTail</a></li>
113 <li><img alt="" src="../images/down.gif" /> <a href="#serveradmin">ServerAdmin</a></li>
114 <li><img alt="" src="../images/down.gif" /> <a href="#serveralias">ServerAlias</a></li>
115 <li><img alt="" src="../images/down.gif" /> <a href="#servername">ServerName</a></li>
116 <li><img alt="" src="../images/down.gif" /> <a href="#serverpath">ServerPath</a></li>
117 <li><img alt="" src="../images/down.gif" /> <a href="#serverroot">ServerRoot</a></li>
118 <li><img alt="" src="../images/down.gif" /> <a href="#serversignature">ServerSignature</a></li>
119 <li><img alt="" src="../images/down.gif" /> <a href="#servertokens">ServerTokens</a></li>
120 <li><img alt="" src="../images/down.gif" /> <a href="#sethandler">SetHandler</a></li>
121 <li><img alt="" src="../images/down.gif" /> <a href="#setinputfilter">SetInputFilter</a></li>
122 <li><img alt="" src="../images/down.gif" /> <a href="#setoutputfilter">SetOutputFilter</a></li>
123 <li><img alt="" src="../images/down.gif" /> <a href="#timeout">TimeOut</a></li>
124 <li><img alt="" src="../images/down.gif" /> <a href="#traceenable">TraceEnable</a></li>
125 <li><img alt="" src="../images/down.gif" /> <a href="#undefine">UnDefine</a></li>
126 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalname">UseCanonicalName</a></li>
127 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></li>
128 <li><img alt="" src="../images/down.gif" /> <a href="#virtualhost"><VirtualHost></a></li>
129 <li><img alt="" src="../images/down.gif" /> <a href="#warning">Warning</a></li>
131 <h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=core">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=core">Report a bug</a></li></ul><h3>See also</h3>
133 <li><a href="#comments_section">Comments</a></li></ul></div>
135 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
136 <div class="directive-section"><h2><a name="AcceptFilter" id="AcceptFilter">AcceptFilter</a> <a name="acceptfilter" id="acceptfilter">Directive</a></h2>
137 <table class="directive">
138 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures optimizations for a Protocol's Listener Sockets</td></tr>
139 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptFilter <var>protocol</var> <var>accept_filter</var></code></td></tr>
140 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
141 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
142 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
144 <p>This directive enables operating system specific optimizations for a
145 listening socket by the <code class="directive">Protocol</code> type.
146 The basic premise is for the kernel to not send a socket to the server
147 process until either data is received or an entire HTTP Request is buffered.
148 Only <a href="http://www.freebsd.org/cgi/man.cgi?query=accept_filter&sektion=9">
149 FreeBSD's Accept Filters</a>, Linux's more primitive
150 <code>TCP_DEFER_ACCEPT</code>, and Windows' optimized AcceptEx()
151 are currently supported.</p>
153 <p>Using <code>none</code> for an argument will disable any accept filters
154 for that protocol. This is useful for protocols that require a server
155 send data first, such as <code>ftp:</code> or <code>nntp</code>:</p>
156 <pre class="prettyprint lang-config">AcceptFilter nntp none</pre>
159 <p>The default protocol names are <code>https</code> for port 443
160 and <code>http</code> for all other ports. To specify that another
161 protocol is being used with a listening port, add the <var>protocol</var>
162 argument to the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>
165 <p>The default values on FreeBSD are:</p>
166 <pre class="prettyprint lang-config">AcceptFilter http httpready
167 AcceptFilter https dataready</pre>
170 <p>The <code>httpready</code> accept filter buffers entire HTTP requests at
171 the kernel level. Once an entire request is received, the kernel then
172 sends it to the server. See the
173 <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_http&sektion=9">
174 accf_http(9)</a> man page for more details. Since HTTPS requests are
175 encrypted, only the <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_data&sektion=9">
176 accf_data(9)</a> filter is used.</p>
178 <p>The default values on Linux are:</p>
179 <pre class="prettyprint lang-config">AcceptFilter http data
180 AcceptFilter https data</pre>
183 <p>Linux's <code>TCP_DEFER_ACCEPT</code> does not support buffering http
184 requests. Any value besides <code>none</code> will enable
185 <code>TCP_DEFER_ACCEPT</code> on that listener. For more details
187 <a href="http://homepages.cwi.nl/~aeb/linux/man2html/man7/tcp.7.html">
188 tcp(7)</a> man page.</p>
190 <p>The default values on Windows are:</p>
191 <pre class="prettyprint lang-config">AcceptFilter http data
192 AcceptFilter https data</pre>
195 <p>Window's mpm_winnt interprets the AcceptFilter to toggle the AcceptEx()
196 API, and does not support http protocol buffering. There are two values
197 which utilize the Windows AcceptEx() API and will recycle network
198 sockets between connections. <code>data</code> waits until data has
199 been transmitted as documented above, and the initial data buffer and
200 network endpoint addresses are all retrieved from the single AcceptEx()
201 invocation. <code>connect</code> will use the AcceptEx() API, also
202 retrieve the network endpoint addresses, but like <code>none</code>
203 the <code>connect</code> option does not wait for the initial data
206 <p>On Windows, <code>none</code> uses accept() rather than AcceptEx()
207 and will not recycle sockets between connections. This is useful for
208 network adapters with broken driver support, as well as some virtual
209 network providers such as vpn drivers, or spam, virus or spyware
215 <li><code class="directive"><a href="#protocol">Protocol</a></code></li>
218 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
219 <div class="directive-section"><h2><a name="AcceptPathInfo" id="AcceptPathInfo">AcceptPathInfo</a> <a name="acceptpathinfo" id="acceptpathinfo">Directive</a></h2>
220 <table class="directive">
221 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Resources accept trailing pathname information</td></tr>
222 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptPathInfo On|Off|Default</code></td></tr>
223 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AcceptPathInfo Default</code></td></tr>
224 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
225 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
226 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
227 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
230 <p>This directive controls whether requests that contain trailing
231 pathname information that follows an actual filename (or
232 non-existent file in an existing directory) will be accepted or
233 rejected. The trailing pathname information can be made
234 available to scripts in the <code>PATH_INFO</code> environment
237 <p>For example, assume the location <code>/test/</code> points to
238 a directory that contains only the single file
239 <code>here.html</code>. Then requests for
240 <code>/test/here.html/more</code> and
241 <code>/test/nothere.html/more</code> both collect
242 <code>/more</code> as <code>PATH_INFO</code>.</p>
244 <p>The three possible arguments for the
245 <code class="directive">AcceptPathInfo</code> directive are:</p>
247 <dt><code>Off</code></dt><dd>A request will only be accepted if it
248 maps to a literal path that exists. Therefore a request with
249 trailing pathname information after the true filename such as
250 <code>/test/here.html/more</code> in the above example will return
251 a 404 NOT FOUND error.</dd>
253 <dt><code>On</code></dt><dd>A request will be accepted if a
254 leading path component maps to a file that exists. The above
255 example <code>/test/here.html/more</code> will be accepted if
256 <code>/test/here.html</code> maps to a valid file.</dd>
258 <dt><code>Default</code></dt><dd>The treatment of requests with
259 trailing pathname information is determined by the <a href="../handler.html">handler</a> responsible for the request.
260 The core handler for normal files defaults to rejecting
261 <code>PATH_INFO</code> requests. Handlers that serve scripts, such as <a href="mod_cgi.html">cgi-script</a> and <a href="mod_isapi.html">isapi-handler</a>, generally accept
262 <code>PATH_INFO</code> by default.</dd>
265 <p>The primary purpose of the <code>AcceptPathInfo</code>
266 directive is to allow you to override the handler's choice of
267 accepting or rejecting <code>PATH_INFO</code>. This override is required,
268 for example, when you use a <a href="../filter.html">filter</a>, such
269 as <a href="mod_include.html">INCLUDES</a>, to generate content
270 based on <code>PATH_INFO</code>. The core handler would usually reject
271 the request, so you can use the following configuration to enable
274 <pre class="prettyprint lang-config"><Files "mypaths.shtml">
276 SetOutputFilter INCLUDES
283 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
284 <div class="directive-section"><h2><a name="AccessFileName" id="AccessFileName">AccessFileName</a> <a name="accessfilename" id="accessfilename">Directive</a></h2>
285 <table class="directive">
286 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Name of the distributed configuration file</td></tr>
287 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AccessFileName <var>filename</var> [<var>filename</var>] ...</code></td></tr>
288 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AccessFileName .htaccess</code></td></tr>
289 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
290 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
291 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
293 <p>While processing a request, the server looks for
294 the first existing configuration file from this list of names in
295 every directory of the path to the document, if distributed
296 configuration files are <a href="#allowoverride">enabled for that
297 directory</a>. For example:</p>
299 <pre class="prettyprint lang-config">AccessFileName .acl</pre>
302 <p>Before returning the document
303 <code>/usr/local/web/index.html</code>, the server will read
304 <code>/.acl</code>, <code>/usr/.acl</code>,
305 <code>/usr/local/.acl</code> and <code>/usr/local/web/.acl</code>
306 for directives unless they have been disabled with:</p>
308 <pre class="prettyprint lang-config"><Directory "/">
310 </Directory></pre>
315 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
316 <li><a href="../configuring.html">Configuration Files</a></li>
317 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
320 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
321 <div class="directive-section"><h2><a name="AddDefaultCharset" id="AddDefaultCharset">AddDefaultCharset</a> <a name="adddefaultcharset" id="adddefaultcharset">Directive</a></h2>
322 <table class="directive">
323 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Default charset parameter to be added when a response
324 content-type is <code>text/plain</code> or <code>text/html</code></td></tr>
325 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AddDefaultCharset On|Off|<var>charset</var></code></td></tr>
326 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AddDefaultCharset Off</code></td></tr>
327 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
328 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
329 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
330 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
332 <p>This directive specifies a default value for the media type
333 charset parameter (the name of a character encoding) to be added
334 to a response if and only if the response's content-type is either
335 <code>text/plain</code> or <code>text/html</code>. This should override
336 any charset specified in the body of the response via a <code>META</code>
337 element, though the exact behavior is often dependent on the user's client
338 configuration. A setting of <code>AddDefaultCharset Off</code>
339 disables this functionality. <code>AddDefaultCharset On</code> enables
340 a default charset of <code>iso-8859-1</code>. Any other value is assumed
341 to be the <var>charset</var> to be used, which should be one of the
342 <a href="http://www.iana.org/assignments/character-sets">IANA registered
343 charset values</a> for use in Internet media types (MIME types).
346 <pre class="prettyprint lang-config">AddDefaultCharset utf-8</pre>
349 <p><code class="directive">AddDefaultCharset</code> should only be used when all
350 of the text resources to which it applies are known to be in that
351 character encoding and it is too inconvenient to label their charset
352 individually. One such example is to add the charset parameter
353 to resources containing generated content, such as legacy CGI
354 scripts, that might be vulnerable to cross-site scripting attacks
355 due to user-provided data being included in the output. Note, however,
356 that a better solution is to just fix (or delete) those scripts, since
357 setting a default charset does not protect users that have enabled
358 the "auto-detect character encoding" feature on their browser.</p>
362 <li><code class="directive"><a href="../mod/mod_mime.html#addcharset">AddCharset</a></code></li>
365 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
366 <div class="directive-section"><h2><a name="AllowEncodedSlashes" id="AllowEncodedSlashes">AllowEncodedSlashes</a> <a name="allowencodedslashes" id="allowencodedslashes">Directive</a></h2>
367 <table class="directive">
368 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether encoded path separators in URLs are allowed to
369 be passed through</td></tr>
370 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowEncodedSlashes On|Off|NoDecode</code></td></tr>
371 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowEncodedSlashes Off</code></td></tr>
372 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
373 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
374 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
375 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>
376 NoDecode option available in 2.3.12 and later.</td></tr>
378 <p>The <code class="directive">AllowEncodedSlashes</code> directive allows URLs
379 which contain encoded path separators (<code>%2F</code> for <code>/</code>
380 and additionally <code>%5C</code> for <code>\</code> on accordant systems)
381 to be used in the path info.</p>
383 <p>With the default value, <code>Off</code>, such URLs are refused
384 with a 404 (Not found) error.</p>
386 <p>With the value <code>On</code>, such URLs are accepted, and encoded
387 slashes are decoded like all other encoded characters.</p>
389 <p>With the value <code>NoDecode</code>, such URLs are accepted, but
390 encoded slashes are not decoded but left in their encoded state.</p>
392 <p>Turning <code class="directive">AllowEncodedSlashes</code> <code>On</code> is
393 mostly useful when used in conjunction with <code>PATH_INFO</code>.</p>
395 <div class="note"><h3>Note</h3>
396 <p>If encoded slashes are needed in path info, use of <code>NoDecode</code> is
397 strongly recommended as a security measure. Allowing slashes
398 to be decoded could potentially allow unsafe paths.</p>
403 <li><code class="directive"><a href="#acceptpathinfo">AcceptPathInfo</a></code></li>
406 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
407 <div class="directive-section"><h2><a name="AllowOverride" id="AllowOverride">AllowOverride</a> <a name="allowoverride" id="allowoverride">Directive</a></h2>
408 <table class="directive">
409 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Types of directives that are allowed in
410 <code>.htaccess</code> files</td></tr>
411 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverride All|None|<var>directive-type</var>
412 [<var>directive-type</var>] ...</code></td></tr>
413 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowOverride None (2.3.9 and later), AllowOverride All (2.3.8 and earlier)</code></td></tr>
414 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
415 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
416 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
418 <p>When the server finds an <code>.htaccess</code> file (as
419 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>),
420 it needs to know which directives declared in that file can override
421 earlier configuration directives.</p>
423 <div class="note"><h3>Only available in <Directory> sections</h3>
424 <code class="directive">AllowOverride</code> is valid only in
425 <code class="directive"><a href="#directory"><Directory></a></code>
426 sections specified without regular expressions, not in <code class="directive"><a href="#location"><Location></a></code>, <code class="directive"><a href="#directorymatch"><DirectoryMatch></a></code> or
427 <code class="directive"><a href="#files"><Files></a></code> sections.
430 <p>When this directive is set to <code>None</code> and <code class="directive"><a href="#allowoverridelist">AllowOverrideList</a></code> is set to
431 <code>None</code>, <a href="#accessfilename">.htaccess</a> files are
432 completely ignored. In this case, the server will not even attempt
433 to read <code>.htaccess</code> files in the filesystem.</p>
435 <p>When this directive is set to <code>All</code>, then any
436 directive which has the .htaccess <a href="directive-dict.html#Context">Context</a> is allowed in
437 <code>.htaccess</code> files.</p>
439 <p>The <var>directive-type</var> can be one of the following
440 groupings of directives.</p>
447 Allow use of the authorization directives (<code class="directive"><a href="../mod/mod_authz_dbm.html#authdbmgroupfile">AuthDBMGroupFile</a></code>,
448 <code class="directive"><a href="../mod/mod_authn_dbm.html#authdbmuserfile">AuthDBMUserFile</a></code>,
449 <code class="directive"><a href="../mod/mod_authz_groupfile.html#authgroupfile">AuthGroupFile</a></code>,
450 <code class="directive"><a href="../mod/mod_authn_core.html#authname">AuthName</a></code>,
451 <code class="directive"><a href="../mod/mod_authn_core.html#authtype">AuthType</a></code>, <code class="directive"><a href="../mod/mod_authn_file.html#authuserfile">AuthUserFile</a></code>, <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code>, <em>etc.</em>).</dd>
456 Allow use of the directives controlling document types
457 (<code class="directive"><a href="#errordocument">ErrorDocument</a></code>,
458 <code class="directive"><a href="#forcetype">ForceType</a></code>,
459 <code class="directive"><a href="../mod/mod_negotiation.html#languagepriority">LanguagePriority</a></code>,
460 <code class="directive"><a href="#sethandler">SetHandler</a></code>,
461 <code class="directive"><a href="#setinputfilter">SetInputFilter</a></code>,
462 <code class="directive"><a href="#setoutputfilter">SetOutputFilter</a></code>, and
463 <code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code> Add* and Remove* directives),
464 document meta data (<code class="directive"><a href="../mod/mod_headers.html#header">Header</a></code>, <code class="directive"><a href="../mod/mod_headers.html#requestheader">RequestHeader</a></code>, <code class="directive"><a href="../mod/mod_setenvif.html#setenvif">SetEnvIf</a></code>, <code class="directive"><a href="../mod/mod_setenvif.html#setenvifnocase">SetEnvIfNoCase</a></code>, <code class="directive"><a href="../mod/mod_setenvif.html#browsermatch">BrowserMatch</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookieexpires">CookieExpires</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookiedomain">CookieDomain</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookiestyle">CookieStyle</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookietracking">CookieTracking</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookiename">CookieName</a></code>),
465 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> directives (<code class="directive"><a href="../mod/mod_rewrite.html#rewriteengine">RewriteEngine</a></code>, <code class="directive"><a href="../mod/mod_rewrite.html#rewriteoptions">RewriteOptions</a></code>, <code class="directive"><a href="../mod/mod_rewrite.html#rewritebase">RewriteBase</a></code>, <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code>, <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code>),
466 <code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code> directives (<code class="directive"><a href="../mod/mod_alias.html#redirect">Redirect</a></code>, <code class="directive"><a href="../mod/mod_alias.html#redirecttemp">RedirectTemp</a></code>, <code class="directive"><a href="../mod/mod_alias.html#redirectpermanent">RedirectPermanent</a></code>, <code class="directive"><a href="../mod/mod_alias.html#redirectmatch">RedirectMatch</a></code>), and
467 <code class="directive"><a href="../mod/mod_actions.html#action">Action</a></code> from
468 <code class="module"><a href="../mod/mod_actions.html">mod_actions</a></code>.
474 Allow use of the directives controlling directory indexing
475 (<code class="directive"><a href="../mod/mod_autoindex.html#adddescription">AddDescription</a></code>,
476 <code class="directive"><a href="../mod/mod_autoindex.html#addicon">AddIcon</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#addiconbyencoding">AddIconByEncoding</a></code>,
477 <code class="directive"><a href="../mod/mod_autoindex.html#addiconbytype">AddIconByType</a></code>,
478 <code class="directive"><a href="../mod/mod_autoindex.html#defaulticon">DefaultIcon</a></code>, <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>, <code class="directive"><a href="../mod/mod_dir.html#fallbackresource">FallbackResource</a></code>, <a href="mod_autoindex.html#indexoptions.fancyindexing"><code>FancyIndexing</code></a>, <code class="directive"><a href="../mod/mod_autoindex.html#headername">HeaderName</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#indexignore">IndexIgnore</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#indexoptions">IndexOptions</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#readmename">ReadmeName</a></code>,
484 Allow use of the directives controlling host access (<code class="directive"><a href="../mod/mod_access_compat.html#allow">Allow</a></code>, <code class="directive"><a href="../mod/mod_access_compat.html#deny">Deny</a></code> and <code class="directive"><a href="../mod/mod_access_compat.html#order">Order</a></code>).</dd>
489 <dt>Nonfatal=[Override|Unknown|All]</dt>
492 Allow use of AllowOverride option to treat invalid (unrecognized
493 or disallowed) directives in
494 .htaccess as nonfatal. Instead of causing an Internal Server
495 Error, disallowed or unrecognised directives will be ignored
496 and a warning logged:
498 <li><strong>Nonfatal=Override</strong> treats directives
499 forbidden by AllowOverride as nonfatal.</li>
500 <li><strong>Nonfatal=Unknown</strong> treats unknown directives
501 as nonfatal. This covers typos and directives implemented
502 by a module that's not present.</li>
503 <li><strong>Nonfatal=All</strong> treats both the above as nonfatal.</li>
505 <p>Note that a syntax error in a valid directive will still cause
506 an Internal Server Error.</p>
507 <div class="warning"><h3>Security</h3>
508 Nonfatal errors may have security implications for .htaccess users.
509 For example, if AllowOverride disallows AuthConfig, users'
510 configuration designed to restrict access to a site will be disabled.
514 <dt>Options[=<var>Option</var>,...]</dt>
517 Allow use of the directives controlling specific directory
518 features (<code class="directive"><a href="#options">Options</a></code> and
519 <code class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></code>).
520 An equal sign may be given followed by a comma-separated list, without
521 spaces, of options that may be set using the <code class="directive"><a href="#options">Options</a></code> command.
523 <div class="note"><h3>Implicit disabling of Options</h3>
524 <p>Even though the list of options that may be used in .htaccess files
525 can be limited with this directive, as long as any <code class="directive"><a href="#options">Options</a></code> directive is allowed any
526 other inherited option can be disabled by using the non-relative
527 syntax. In other words, this mechanism cannot force a specific option
528 to remain <em>set</em> while allowing any others to be set.
531 <div class="example"><p><code>
532 AllowOverride Options=Indexes,MultiViews
539 <pre class="prettyprint lang-config">AllowOverride AuthConfig Indexes</pre>
542 <p>In the example above, all directives that are neither in the group
543 <code>AuthConfig</code> nor <code>Indexes</code> cause an internal
546 <div class="note"><p>For security and performance reasons, do not set
547 <code>AllowOverride</code> to anything other than <code>None</code>
548 in your <code><Directory "/"></code> block. Instead, find (or
549 create) the <code><Directory></code> block that refers to the
550 directory where you're actually planning to place a
551 <code>.htaccess</code> file.</p>
556 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
557 <li><code class="directive"><a href="#allowoverridelist">AllowOverrideList</a></code></li>
558 <li><a href="../configuring.html">Configuration Files</a></li>
559 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
562 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
563 <div class="directive-section"><h2><a name="AllowOverrideList" id="AllowOverrideList">AllowOverrideList</a> <a name="allowoverridelist" id="allowoverridelist">Directive</a></h2>
564 <table class="directive">
565 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Individual directives that are allowed in
566 <code>.htaccess</code> files</td></tr>
567 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverrideList None|<var>directive</var>
568 [<var>directive-type</var>] ...</code></td></tr>
569 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowOverrideList None</code></td></tr>
570 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
571 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
572 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
574 <p>When the server finds an <code>.htaccess</code> file (as
575 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>),
576 it needs to know which directives declared in that file can override
577 earlier configuration directives.</p>
579 <div class="note"><h3>Only available in <Directory> sections</h3>
580 <code class="directive">AllowOverrideList</code> is valid only in
581 <code class="directive"><a href="#directory"><Directory></a></code>
582 sections specified without regular expressions, not in <code class="directive"><a href="#location"><Location></a></code>, <code class="directive"><a href="#directorymatch"><DirectoryMatch></a></code> or
583 <code class="directive"><a href="#files"><Files></a></code> sections.
586 <p>When this directive is set to <code>None</code> and <code class="directive"><a href="#allowoverride">AllowOverride</a></code> is set to <code>None</code>,
587 then <a href="#accessfilename">.htaccess</a> files are completely
588 ignored. In this case, the server will not even attempt to read
589 <code>.htaccess</code> files in the filesystem.</p>
593 <pre class="prettyprint lang-config">AllowOverride None
594 AllowOverrideList Redirect RedirectMatch</pre>
597 <p>In the example above, only the <code>Redirect</code> and
598 <code>RedirectMatch</code> directives are allowed. All others will
599 cause an Internal Server Error.</p>
603 <pre class="prettyprint lang-config">AllowOverride AuthConfig
604 AllowOverrideList CookieTracking CookieName</pre>
607 <p>In the example above, <code class="directive"><a href="#allowoverride">AllowOverride
608 </a></code> grants permission to the <code>AuthConfig</code>
609 directive grouping and <code class="directive">AllowOverrideList</code> grants
610 permission to only two directives from the <code>FileInfo</code> directive
611 grouping. All others will cause an Internal Server Error.</p>
615 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
616 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
617 <li><a href="../configuring.html">Configuration Files</a></li>
618 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
621 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
622 <div class="directive-section"><h2><a name="AsyncFilter" id="AsyncFilter">AsyncFilter</a> <a name="asyncfilter" id="asyncfilter">Directive</a></h2>
623 <table class="directive">
624 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Set the minimum filter type eligible for asynchronous handling</td></tr>
625 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AsyncFilter request|connection|network</code></td></tr>
626 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AsyncFilter request</code></td></tr>
627 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
628 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
629 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
630 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.5.0 and later.</td></tr>
632 <p>This directive controls the minimum filter levels that are eligible
633 for asynchronous handling. This may be necessary to support legacy external
634 filters that did not handle meta buckets correctly.</p>
636 <p>If set to "network", asynchronous handling will be limited to the network
637 filter only. If set to "connection", all connection and network filters
638 will be eligible for asynchronous handling, including <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code>.
639 If set to "request", all filters will be eligible for asynchronous handling.</p>
642 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
643 <div class="directive-section"><h2><a name="CGIMapExtension" id="CGIMapExtension">CGIMapExtension</a> <a name="cgimapextension" id="cgimapextension">Directive</a></h2>
644 <table class="directive">
645 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
647 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIMapExtension <var>cgi-path</var> <var>.extension</var></code></td></tr>
648 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
649 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
650 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
651 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
652 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>NetWare only</td></tr>
654 <p>This directive is used to control how Apache httpd finds the
655 interpreter used to run CGI scripts. For example, setting
656 <code>CGIMapExtension sys:\foo.nlm .foo</code> will
657 cause all CGI script files with a <code>.foo</code> extension to
658 be passed to the FOO interpreter.</p>
661 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
662 <div class="directive-section"><h2><a name="CGIPassAuth" id="CGIPassAuth">CGIPassAuth</a> <a name="cgipassauth" id="cgipassauth">Directive</a></h2>
663 <table class="directive">
664 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables passing HTTP authorization headers to scripts as CGI
666 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIPassAuth On|Off</code></td></tr>
667 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CGIPassAuth Off</code></td></tr>
668 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
669 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig</td></tr>
670 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
671 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
672 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.4.13 and later</td></tr>
674 <p><code class="directive">CGIPassAuth</code> allows scripts access to HTTP
675 authorization headers such as <code>Authorization</code>, which is
676 required for scripts that implement HTTP Basic authentication.
677 Normally these HTTP headers are hidden from scripts. This is to disallow
678 scripts from seeing user ids and passwords used to access the server when
679 HTTP Basic authentication is enabled in the web server. This directive
680 should be used when scripts are allowed to implement HTTP Basic
683 <p>This directive can be used instead of the compile-time setting
684 <code>SECURITY_HOLE_PASS_AUTHORIZATION</code> which has been available
685 in previous versions of Apache HTTP Server.</p>
687 <p>The setting is respected by any modules which use
688 <code>ap_add_common_vars()</code>, such as <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>,
689 <code class="module"><a href="../mod/mod_cgid.html">mod_cgid</a></code>, <code class="module"><a href="../mod/mod_proxy_fcgi.html">mod_proxy_fcgi</a></code>,
690 <code class="module"><a href="../mod/mod_proxy_scgi.html">mod_proxy_scgi</a></code>, and so on. Notably, it affects
691 modules which don't handle the request in the usual sense but
692 still use this API; examples of this are <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
693 and <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>. Third-party modules that don't
694 use <code>ap_add_common_vars()</code> may choose to respect the setting
698 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
699 <div class="directive-section"><h2><a name="CGIVar" id="CGIVar">CGIVar</a> <a name="cgivar" id="cgivar">Directive</a></h2>
700 <table class="directive">
701 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls how some CGI variables are set</td></tr>
702 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIVar <var>variable</var> <var>rule</var></code></td></tr>
703 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
704 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
705 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
706 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
707 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.4.21 and later</td></tr>
709 <p>This directive controls how some CGI variables are set.</p>
711 <p><strong>REQUEST_URI</strong> rules:</p>
713 <dt><code>original-uri</code> (default)</dt>
714 <dd>The value is taken from the original request line, and will not
715 reflect internal redirects or subrequests which change the requested
717 <dt><code>current-uri</code></dt>
718 <dd>The value reflects the resource currently being processed,
719 which may be different than the original request from the client
720 due to internal redirects or subrequests.</dd>
724 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
725 <div class="directive-section"><h2><a name="ContentDigest" id="ContentDigest">ContentDigest</a> <a name="contentdigest" id="contentdigest">Directive</a></h2>
726 <table class="directive">
727 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables the generation of <code>Content-MD5</code> HTTP Response
729 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ContentDigest On|Off</code></td></tr>
730 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ContentDigest Off</code></td></tr>
731 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
732 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
733 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
734 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
736 <p>This directive enables the generation of
737 <code>Content-MD5</code> headers as defined in RFC1864
738 respectively RFC2616.</p>
740 <p>MD5 is an algorithm for computing a "message digest"
741 (sometimes called "fingerprint") of arbitrary-length data, with
742 a high degree of confidence that any alterations in the data
743 will be reflected in alterations in the message digest.</p>
745 <p>The <code>Content-MD5</code> header provides an end-to-end
746 message integrity check (MIC) of the entity-body. A proxy or
747 client may check this header for detecting accidental
748 modification of the entity-body in transit. Example header:</p>
750 <div class="example"><p><code>
751 Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
754 <p>Note that this can cause performance problems on your server
755 since the message digest is computed on every request (the
756 values are not cached).</p>
758 <p><code>Content-MD5</code> is only sent for documents served
759 by the <code class="module"><a href="../mod/core.html">core</a></code>, and not by any module. For example,
760 SSI documents, output from CGI scripts, and byte range responses
761 do not have this header.</p>
764 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
765 <div class="directive-section"><h2><a name="DefaultRuntimeDir" id="DefaultRuntimeDir">DefaultRuntimeDir</a> <a name="defaultruntimedir" id="defaultruntimedir">Directive</a></h2>
766 <table class="directive">
767 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server run-time files</td></tr>
768 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultRuntimeDir <var>directory-path</var></code></td></tr>
769 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultRuntimeDir DEFAULT_REL_RUNTIMEDIR (logs/)</code></td></tr>
770 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
771 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
772 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
773 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.4.2 and later</td></tr>
775 <p>The <code class="directive">DefaultRuntimeDir</code> directive sets the
776 directory in which the server will create various run-time files
777 (shared memory, locks, etc.). If set as a relative path, the full path
778 will be relative to <code class="directive">ServerRoot</code>.</p>
780 <p><strong>Example</strong></p>
781 <pre class="prettyprint lang-config">DefaultRuntimeDir scratch/</pre>
784 <p>The default location of <code class="directive">DefaultRuntimeDir</code> may be
785 modified by changing the <code>DEFAULT_REL_RUNTIMEDIR</code> #define
788 <p>Note: <code class="directive">ServerRoot</code> should be specified before this
789 directive is used. Otherwise, the default value of <code class="directive">ServerRoot</code>
790 would be used to set the base directory.</p>
795 <li><a href="../misc/security_tips.html#serverroot">the
796 security tips</a> for information on how to properly set
797 permissions on the <code class="directive">ServerRoot</code></li>
800 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
801 <div class="directive-section"><h2><a name="DefaultType" id="DefaultType">DefaultType</a> <a name="defaulttype" id="defaulttype">Directive</a></h2>
802 <table class="directive">
803 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>This directive has no effect other than to emit warnings
804 if the value is not <code>none</code>. In prior versions, DefaultType
805 would specify a default media type to assign to response content for
806 which no other media type configuration could be found.
808 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultType <var>media-type|none</var></code></td></tr>
809 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultType none</code></td></tr>
810 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
811 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
812 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
813 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
814 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>All choices except <code>none</code> are DISABLED for 2.3.x and later.
817 <p>This directive has been disabled. For backwards compatibility
818 of configuration files, it may be specified with the value
819 <code>none</code>, meaning no default media type. For example:</p>
821 <pre class="prettyprint lang-config">DefaultType None</pre>
824 <p><code>DefaultType None</code> is only available in
825 httpd-2.2.7 and later.</p>
827 <p>Use the mime.types configuration file and the
828 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code> to configure media
829 type assignments via file extensions, or the
830 <code class="directive"><a href="#forcetype">ForceType</a></code> directive to configure
831 the media type for specific resources. Otherwise, the server will
832 send the response without a Content-Type header field and the
833 recipient may attempt to guess the media type.</p>
836 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
837 <div class="directive-section"><h2><a name="Define" id="Define">Define</a> <a name="define" id="define">Directive</a></h2>
838 <table class="directive">
839 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Define a variable</td></tr>
840 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Define <var>parameter-name</var> [<var>parameter-value</var>]</code></td></tr>
841 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
842 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
843 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
845 <p>In its one parameter form, <code class="directive">Define</code> is equivalent
846 to passing the <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>. It
847 can be used to toggle the use of
848 <code class="directive"><a href="#ifdefine"><IfDefine></a></code> sections
849 without needing to alter <code>-D</code> arguments in any startup
852 <p>In addition to that, if the second parameter is given, a config variable
853 is set to this value. The variable can be used in the configuration using
854 the <code>${VAR}</code> syntax. The variable is always globally defined
855 and not limited to the scope of the surrounding config section.</p>
857 <pre class="prettyprint lang-config"><IfDefine TEST>
858 Define servername test.example.com
860 <IfDefine !TEST>
861 Define servername www.example.com
865 DocumentRoot "/var/www/${servername}/htdocs"</pre>
868 <p>Variable names may not contain colon ":" characters, to avoid clashes
869 with <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>'s syntax.</p>
871 <p>While this directive is supported in virtual host context,
872 the changes it makes are visible to any later configuration
873 directives, beyond any enclosing virtual host</p>
876 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
877 <div class="directive-section"><h2><a name="Directory" id="Directory"><Directory></a> <a name="directory" id="directory">Directive</a></h2>
878 <table class="directive">
879 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose a group of directives that apply only to the
880 named file-system directory, sub-directories, and their contents.</td></tr>
881 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Directory <var>directory-path</var>>
882 ... </Directory></code></td></tr>
883 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
884 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
885 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
887 <p><code class="directive"><Directory></code> and
888 <code></Directory></code> are used to enclose a group of
889 directives that will apply only to the named directory,
890 sub-directories of that directory, and the files within the respective
891 directories. Any directive that is allowed
892 in a directory context may be used. <var>Directory-path</var> is
893 either the full path to a directory, or a wild-card string using
894 Unix shell-style matching. In a wild-card string, <code>?</code> matches
895 any single character, and <code>*</code> matches any sequences of
896 characters. You may also use <code>[]</code> character ranges. None
897 of the wildcards match a `/' character, so <code><Directory
898 "/*/public_html"></code> will not match
899 <code>/home/user/public_html</code>, but <code><Directory
900 "/home/*/public_html"></code> will match. Example:</p>
902 <pre class="prettyprint lang-config"><Directory "/usr/local/httpd/htdocs">
903 Options Indexes FollowSymLinks
904 </Directory></pre>
907 <p>Directory paths <em>may</em> be quoted, if you like, however, it
908 <em>must</em> be quoted if the path contains spaces. This is because a
909 space would otherwise indicate the end of an argument.</p>
912 <p>Be careful with the <var>directory-path</var> arguments:
913 They have to literally match the filesystem path which Apache httpd uses
914 to access the files. Directives applied to a particular
915 <code><Directory></code> will not apply to files accessed from
916 that same directory via a different path, such as via different symbolic
920 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular
921 expressions</a> can also be used, with the addition of the
922 <code>~</code> character. For example:</p>
924 <pre class="prettyprint lang-config"><Directory ~ "^/www/[0-9]{3}">
926 </Directory></pre>
929 <p>would match directories in <code>/www/</code> that consisted of
932 <p>If multiple (non-regular expression) <code class="directive"><Directory></code> sections
933 match the directory (or one of its parents) containing a document,
934 then the directives are applied in the order of shortest match
935 first, interspersed with the directives from the <a href="#accessfilename">.htaccess</a> files. For example,
938 <pre class="prettyprint lang-config"><Directory "/">
942 <Directory "/home">
943 AllowOverride FileInfo
944 </Directory></pre>
947 <p>for access to the document <code>/home/web/dir/doc.html</code>
951 <li>Apply directive <code>AllowOverride None</code>
952 (disabling <code>.htaccess</code> files).</li>
954 <li>Apply directive <code>AllowOverride FileInfo</code> (for
955 directory <code>/home</code>).</li>
957 <li>Apply any <code>FileInfo</code> directives in
958 <code>/home/.htaccess</code>, <code>/home/web/.htaccess</code> and
959 <code>/home/web/dir/.htaccess</code> in that order.</li>
962 <p>Regular expressions are not considered until after all of the
963 normal sections have been applied. Then all of the regular
964 expressions are tested in the order they appeared in the
965 configuration file. For example, with</p>
967 <pre class="prettyprint lang-config"><Directory ~ "abc$">
968 # ... directives here ...
969 </Directory></pre>
972 <p>the regular expression section won't be considered until after
973 all normal <code class="directive"><Directory></code>s and
974 <code>.htaccess</code> files have been applied. Then the regular
975 expression will match on <code>/home/abc/public_html/abc</code> and
976 the corresponding <code class="directive"><Directory></code> will
979 <p><strong>Note that the default access for
980 <code><Directory "/"></code> is to permit all access.
981 This means that Apache httpd will serve any file mapped from an URL. It is
982 recommended that you change this with a block such
985 <pre class="prettyprint lang-config"><Directory "/">
987 </Directory></pre>
990 <p><strong>and then override this for directories you
991 <em>want</em> accessible. See the <a href="../misc/security_tips.html">Security Tips</a> page for more
992 details.</strong></p>
994 <p>The directory sections occur in the <code>httpd.conf</code> file.
995 <code class="directive"><Directory></code> directives
996 cannot nest, and cannot appear in a <code class="directive"><a href="#limit"><Limit></a></code> or <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section.</p>
1000 <li><a href="../sections.html">How <Directory>,
1001 <Location> and <Files> sections work</a> for an
1002 explanation of how these different sections are combined when a
1003 request is received</li>
1006 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1007 <div class="directive-section"><h2><a name="DirectoryMatch" id="DirectoryMatch"><DirectoryMatch></a> <a name="directorymatch" id="directorymatch">Directive</a></h2>
1008 <table class="directive">
1009 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose directives that apply to
1010 the contents of file-system directories matching a regular expression.</td></tr>
1011 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><DirectoryMatch <var>regex</var>>
1012 ... </DirectoryMatch></code></td></tr>
1013 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1014 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1015 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1017 <p><code class="directive"><DirectoryMatch></code> and
1018 <code></DirectoryMatch></code> are used to enclose a group
1019 of directives which will apply only to the named directory (and the files within),
1020 the same as <code class="directive"><a href="#directory"><Directory></a></code>.
1021 However, it takes as an argument a
1022 <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>. For example:</p>
1024 <pre class="prettyprint lang-config"><DirectoryMatch "^/www/(.+/)?[0-9]{3}/">
1026 </DirectoryMatch></pre>
1029 <p>matches directories in <code>/www/</code> (or any subdirectory thereof)
1030 that consist of three numbers.</p>
1032 <div class="note"><h3>Compatability</h3>
1033 Prior to 2.3.9, this directive implicitly applied to sub-directories
1034 (like <code class="directive"><a href="#directory"><Directory></a></code>) and
1035 could not match the end of line symbol ($). In 2.3.9 and later,
1036 only directories that match the expression are affected by the enclosed
1040 <div class="note"><h3>Trailing Slash</h3>
1041 This directive applies to requests for directories that may or may
1042 not end in a trailing slash, so expressions that are anchored to the
1043 end of line ($) must be written with care.
1046 <p>From 2.4.8 onwards, named groups and backreferences are captured and
1047 written to the environment with the corresponding name prefixed with
1048 "MATCH_" and in upper case. This allows elements of paths to be referenced
1049 from within <a href="../expr.html">expressions</a> and modules like
1050 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
1051 (unnamed) backreferences are ignored. Use named groups instead.</p>
1053 <pre class="prettyprint lang-config"><DirectoryMatch "^/var/www/combined/(?<sitename>[^/]+)">
1054 Require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
1055 </DirectoryMatch></pre>
1060 <li><code class="directive"><a href="#directory"><Directory></a></code> for
1061 a description of how regular expressions are mixed in with normal
1062 <code class="directive"><Directory></code>s</li>
1063 <li><a href="../sections.html">How <Directory>, <Location> and
1064 <Files> sections work</a> for an explanation of how these different
1065 sections are combined when a request is received</li>
1068 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1069 <div class="directive-section"><h2><a name="DocumentRoot" id="DocumentRoot">DocumentRoot</a> <a name="documentroot" id="documentroot">Directive</a></h2>
1070 <table class="directive">
1071 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory that forms the main document tree visible
1072 from the web</td></tr>
1073 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DocumentRoot <var>directory-path</var></code></td></tr>
1074 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DocumentRoot "/usr/local/apache/htdocs"</code></td></tr>
1075 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1076 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1077 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1079 <p>This directive sets the directory from which <code class="program"><a href="../programs/httpd.html">httpd</a></code>
1080 will serve files. Unless matched by a directive like <code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code>, the server appends the
1081 path from the requested URL to the document root to make the
1082 path to the document. Example:</p>
1084 <pre class="prettyprint lang-config">DocumentRoot "/usr/web"</pre>
1087 <p>then an access to
1088 <code>http://my.example.com/index.html</code> refers to
1089 <code>/usr/web/index.html</code>. If the <var>directory-path</var> is
1090 not absolute then it is assumed to be relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1092 <p>The <code class="directive">DocumentRoot</code> should be specified without
1093 a trailing slash.</p>
1097 <li><a href="../urlmapping.html#documentroot">Mapping URLs to Filesystem
1101 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1102 <div class="directive-section"><h2><a name="Else" id="Else"><Else></a> <a name="else" id="else">Directive</a></h2>
1103 <table class="directive">
1104 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if the condition of a
1105 previous <code class="directive"><a href="#if"><If></a></code> or
1106 <code class="directive"><a href="#elseif"><ElseIf></a></code> section is not
1107 satisfied by a request at runtime</td></tr>
1108 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Else> ... </Else></code></td></tr>
1109 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1110 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1111 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1112 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1114 <p>The <code class="directive"><Else></code> applies the enclosed
1115 directives if and only if the most recent
1116 <code class="directive"><If></code> or
1117 <code class="directive"><ElseIf></code> section
1118 in the same scope has not been applied.
1119 For example: In </p>
1121 <pre class="prettyprint lang-config"><If "-z req('Host')">
1129 <p> The <code class="directive"><If></code> would match HTTP/1.0
1130 requests without a <var>Host:</var> header and the
1131 <code class="directive"><Else></code> would match requests
1132 with a <var>Host:</var> header.</p>
1137 <li><code class="directive"><a href="#if"><If></a></code></li>
1138 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
1139 <li><a href="../sections.html">How <Directory>, <Location>,
1140 <Files> sections work</a> for an explanation of how these
1141 different sections are combined when a request is received.
1142 <code class="directive"><If></code>,
1143 <code class="directive"><ElseIf></code>, and
1144 <code class="directive"><Else></code> are applied last.</li>
1147 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1148 <div class="directive-section"><h2><a name="ElseIf" id="ElseIf"><ElseIf></a> <a name="elseif" id="elseif">Directive</a></h2>
1149 <table class="directive">
1150 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is satisfied
1151 by a request at runtime while the condition of a previous
1152 <code class="directive"><a href="#if"><If></a></code> or
1153 <code class="directive"><ElseIf></code> section is not
1155 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><ElseIf <var>expression</var>> ... </ElseIf></code></td></tr>
1156 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1157 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1158 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1159 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1161 <p>The <code class="directive"><ElseIf></code> applies the enclosed
1162 directives if and only if both the given condition evaluates to true and
1163 the most recent <code class="directive"><If></code> or
1164 <code class="directive"><ElseIf></code> section in the same scope has
1165 not been applied. For example: In </p>
1167 <pre class="prettyprint lang-config"><If "-R '10.1.0.0/16'">
1170 <ElseIf "-R '10.0.0.0/8'">
1178 <p>The <code class="directive"><ElseIf></code> would match if
1179 the remote address of a request belongs to the subnet 10.0.0.0/8 but
1180 not to the subnet 10.1.0.0/16.</p>
1185 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
1186 for a complete reference and more examples.</li>
1187 <li><code class="directive"><a href="#if"><If></a></code></li>
1188 <li><code class="directive"><a href="#else"><Else></a></code></li>
1189 <li><a href="../sections.html">How <Directory>, <Location>,
1190 <Files> sections work</a> for an explanation of how these
1191 different sections are combined when a request is received.
1192 <code class="directive"><If></code>,
1193 <code class="directive"><ElseIf></code>, and
1194 <code class="directive"><Else></code> are applied last.</li>
1197 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1198 <div class="directive-section"><h2><a name="EnableMMAP" id="EnableMMAP">EnableMMAP</a> <a name="enablemmap" id="enablemmap">Directive</a></h2>
1199 <table class="directive">
1200 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use memory-mapping to read files during delivery</td></tr>
1201 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableMMAP On|Off</code></td></tr>
1202 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableMMAP On</code></td></tr>
1203 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1204 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1205 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1206 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1208 <p>This directive controls whether the <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use
1209 memory-mapping if it needs to read the contents of a file during
1210 delivery. By default, when the handling of a request requires
1211 access to the data within a file -- for example, when delivering a
1212 server-parsed file using <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> -- Apache httpd
1213 memory-maps the file if the OS supports it.</p>
1215 <p>This memory-mapping sometimes yields a performance improvement.
1216 But in some environments, it is better to disable the memory-mapping
1217 to prevent operational problems:</p>
1220 <li>On some multiprocessor systems, memory-mapping can reduce the
1221 performance of the <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</li>
1222 <li>Deleting or truncating a file while <code class="program"><a href="../programs/httpd.html">httpd</a></code>
1223 has it memory-mapped can cause <code class="program"><a href="../programs/httpd.html">httpd</a></code> to
1224 crash with a segmentation fault.
1228 <p>For server configurations that are vulnerable to these problems,
1229 you should disable memory-mapping of delivered files by specifying:</p>
1231 <pre class="prettyprint lang-config">EnableMMAP Off</pre>
1234 <p>For NFS mounted files, this feature may be disabled explicitly for
1235 the offending files by specifying:</p>
1237 <pre class="prettyprint lang-config"><Directory "/path-to-nfs-files">
1239 </Directory></pre>
1243 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1244 <div class="directive-section"><h2><a name="EnableSendfile" id="EnableSendfile">EnableSendfile</a> <a name="enablesendfile" id="enablesendfile">Directive</a></h2>
1245 <table class="directive">
1246 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use the kernel sendfile support to deliver files to the client</td></tr>
1247 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableSendfile On|Off</code></td></tr>
1248 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableSendfile Off</code></td></tr>
1249 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1250 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1251 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1252 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1253 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Default changed to Off in
1254 version 2.3.9.</td></tr>
1256 <p>This directive controls whether <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use the
1257 sendfile support from the kernel to transmit file contents to the client.
1258 By default, when the handling of a request requires no access
1259 to the data within a file -- for example, when delivering a
1260 static file -- Apache httpd uses sendfile to deliver the file contents
1261 without ever reading the file if the OS supports it.</p>
1263 <p>This sendfile mechanism avoids separate read and send operations,
1264 and buffer allocations. But on some platforms or within some
1265 filesystems, it is better to disable this feature to avoid
1266 operational problems:</p>
1269 <li>Some platforms may have broken sendfile support that the build
1270 system did not detect, especially if the binaries were built on
1271 another box and moved to such a machine with broken sendfile
1273 <li>On Linux the use of sendfile triggers TCP-checksum
1274 offloading bugs on certain networking cards when using IPv6.</li>
1275 <li>On Linux on Itanium, <code>sendfile</code> may be unable to handle
1276 files over 2GB in size.</li>
1277 <li>With a network-mounted <code class="directive"><a href="#documentroot">DocumentRoot</a></code> (e.g., NFS, SMB, CIFS, FUSE),
1278 the kernel may be unable to serve the network file through
1282 <p>For server configurations that are not vulnerable to these problems,
1283 you may enable this feature by specifying:</p>
1285 <pre class="prettyprint lang-config">EnableSendfile On</pre>
1288 <p>For network mounted files, this feature may be disabled explicitly
1289 for the offending files by specifying:</p>
1291 <pre class="prettyprint lang-config"><Directory "/path-to-nfs-files">
1293 </Directory></pre>
1295 <p>Please note that the per-directory and .htaccess configuration
1296 of <code class="directive">EnableSendfile</code> is not supported by
1297 <code class="module"><a href="../mod/mod_cache_disk.html">mod_cache_disk</a></code>.
1298 Only global definition of <code class="directive">EnableSendfile</code>
1299 is taken into account by the module.
1303 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1304 <div class="directive-section"><h2><a name="Error" id="Error">Error</a> <a name="error" id="error">Directive</a></h2>
1305 <table class="directive">
1306 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Abort configuration parsing with a custom error message</td></tr>
1307 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Error <var>message</var></code></td></tr>
1308 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1309 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1310 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1311 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.3.9 and later</td></tr>
1313 <p>If an error can be detected within the configuration, this
1314 directive can be used to generate a custom error message, and halt
1315 configuration parsing. The typical use is for reporting required
1316 modules which are missing from the configuration.</p>
1318 <pre class="prettyprint lang-config"># Example
1319 # ensure that mod_include is loaded
1320 <IfModule !include_module>
1321 Error "mod_include is required by mod_foo. Load it with LoadModule."
1324 # ensure that exactly one of SSL,NOSSL is defined
1325 <IfDefine SSL>
1326 <IfDefine NOSSL>
1327 Error "Both SSL and NOSSL are defined. Define only one of them."
1330 <IfDefine !SSL>
1331 <IfDefine !NOSSL>
1332 Error "Either SSL or NOSSL must be defined."
1334 </IfDefine></pre>
1339 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1340 <div class="directive-section"><h2><a name="ErrorDocument" id="ErrorDocument">ErrorDocument</a> <a name="errordocument" id="errordocument">Directive</a></h2>
1341 <table class="directive">
1342 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>What the server will return to the client
1343 in case of an error</td></tr>
1344 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ErrorDocument <var>error-code</var> <var>document</var></code></td></tr>
1345 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1346 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1347 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1348 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1350 <p>In the event of a problem or error, Apache httpd can be configured
1351 to do one of four things,</p>
1354 <li>output a simple hardcoded error message</li>
1356 <li>output a customized message</li>
1358 <li>internally redirect to a local <var>URL-path</var> to handle the
1361 <li>redirect to an external <var>URL</var> to handle the
1365 <p>The first option is the default, while options 2-4 are
1366 configured using the <code class="directive">ErrorDocument</code>
1367 directive, which is followed by the HTTP response code and a URL
1368 or a message. Apache httpd will sometimes offer additional information
1369 regarding the problem/error.</p>
1371 <p>From 2.4.13, <a href="../expr.html">expression syntax</a> can be
1372 used inside the directive to produce dynamic strings and URLs.</p>
1374 <p>URLs can begin with a slash (/) for local web-paths (relative
1375 to the <code class="directive"><a href="#documentroot">DocumentRoot</a></code>), or be a
1376 full URL which the client can resolve. Alternatively, a message
1377 can be provided to be displayed by the browser. Note that deciding
1378 whether the parameter is an URL, a path or a message is performed
1379 before any expression is parsed. Examples:</p>
1381 <pre class="prettyprint lang-config">ErrorDocument 500 http://example.com/cgi-bin/server-error.cgi
1382 ErrorDocument 404 /errors/bad_urls.php
1383 ErrorDocument 401 /subscription_info.html
1384 ErrorDocument 403 "Sorry, can't allow you access today"
1385 ErrorDocument 403 Forbidden!
1386 ErrorDocument 403 /errors/forbidden.py?referrer=%{escape:%{HTTP_REFERER}}</pre>
1389 <p>Additionally, the special value <code>default</code> can be used
1390 to specify Apache httpd's simple hardcoded message. While not required
1391 under normal circumstances, <code>default</code> will restore
1392 Apache httpd's simple hardcoded message for configurations that would
1393 otherwise inherit an existing <code class="directive">ErrorDocument</code>.</p>
1395 <pre class="prettyprint lang-config">ErrorDocument 404 /cgi-bin/bad_urls.pl
1397 <Directory "/web/docs">
1398 ErrorDocument 404 default
1399 </Directory></pre>
1402 <p>Note that when you specify an <code class="directive">ErrorDocument</code>
1403 that points to a remote URL (ie. anything with a method such as
1404 <code>http</code> in front of it), Apache HTTP Server will send a redirect to the
1405 client to tell it where to find the document, even if the
1406 document ends up being on the same server. This has several
1407 implications, the most important being that the client will not
1408 receive the original error status code, but instead will
1409 receive a redirect status code. This in turn can confuse web
1410 robots and other clients which try to determine if a URL is
1411 valid using the status code. In addition, if you use a remote
1412 URL in an <code>ErrorDocument 401</code>, the client will not
1413 know to prompt the user for a password since it will not
1414 receive the 401 status code. Therefore, <strong>if you use an
1415 <code>ErrorDocument 401</code> directive, then it must refer to a local
1416 document.</strong></p>
1418 <p>Microsoft Internet Explorer (MSIE) will by default ignore
1419 server-generated error messages when they are "too small" and substitute
1420 its own "friendly" error messages. The size threshold varies depending on
1421 the type of error, but in general, if you make your error document
1422 greater than 512 bytes, then MSIE will show the server-generated
1423 error rather than masking it. More information is available in
1424 Microsoft Knowledge Base article <a href="http://support.microsoft.com/default.aspx?scid=kb;en-us;Q294807">Q294807</a>.</p>
1426 <p>Although most error messages can be overridden, there are certain
1427 circumstances where the internal messages are used regardless of the
1428 setting of <code class="directive"><a href="#errordocument">ErrorDocument</a></code>. In
1429 particular, if a malformed request is detected, normal request processing
1430 will be immediately halted and the internal error message returned.
1431 This is necessary to guard against security problems caused by
1434 <p>If you are using mod_proxy, you may wish to enable
1435 <code class="directive"><a href="../mod/mod_proxy.html#proxyerroroverride">ProxyErrorOverride</a></code> so that you can provide
1436 custom error messages on behalf of your Origin servers. If you don't enable ProxyErrorOverride,
1437 Apache httpd will not generate custom error documents for proxied content.</p>
1441 <li><a href="../custom-error.html">documentation of
1442 customizable responses</a></li>
1445 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1446 <div class="directive-section"><h2><a name="ErrorLog" id="ErrorLog">ErrorLog</a> <a name="errorlog" id="errorlog">Directive</a></h2>
1447 <table class="directive">
1448 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Location where the server will log errors</td></tr>
1449 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code> ErrorLog <var>file-path</var>|syslog[:<var>facility</var>]</code></td></tr>
1450 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ErrorLog logs/error_log (Unix) ErrorLog logs/error.log (Windows and OS/2)</code></td></tr>
1451 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1452 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1453 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1455 <p>The <code class="directive">ErrorLog</code> directive sets the name of
1456 the file to which the server will log any errors it encounters. If
1457 the <var>file-path</var> is not absolute then it is assumed to be
1458 relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1460 <pre class="prettyprint lang-config">ErrorLog "/var/log/httpd/error_log"</pre>
1463 <p>If the <var>file-path</var>
1464 begins with a pipe character "<code>|</code>" then it is assumed to be a
1465 command to spawn to handle the error log.</p>
1467 <pre class="prettyprint lang-config">ErrorLog "|/usr/local/bin/httpd_errors"</pre>
1470 <p>See the notes on <a href="../logs.html#piped">piped logs</a> for
1471 more information.</p>
1473 <p>Using <code>syslog</code> instead of a filename enables logging
1474 via syslogd(8) if the system supports it and if <code class="module"><a href="../mod/mod_syslog.html">mod_syslog</a></code>
1475 is loaded. The default is to use syslog facility <code>local7</code>,
1476 but you can override this by using the <code>syslog:<var>facility</var></code>
1477 syntax where <var>facility</var> can be one of the names usually documented in
1478 syslog(1). The facility is effectively global, and if it is changed
1479 in individual virtual hosts, the final facility specified affects the
1482 <pre class="prettyprint lang-config">ErrorLog syslog:user</pre>
1485 <p>Additional modules can provide their own ErrorLog providers. The syntax
1486 is similar to the <code>syslog</code> example above.</p>
1488 <p>SECURITY: See the <a href="../misc/security_tips.html#serverroot">security tips</a>
1489 document for details on why your security could be compromised
1490 if the directory where log files are stored is writable by
1491 anyone other than the user that starts the server.</p>
1492 <div class="warning"><h3>Note</h3>
1493 <p>When entering a file path on non-Unix platforms, care should be taken
1494 to make sure that only forward slashes are used even though the platform
1495 may allow the use of back slashes. In general it is a good idea to always
1496 use forward slashes throughout the configuration files.</p>
1501 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1502 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1505 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1506 <div class="directive-section"><h2><a name="ErrorLogFormat" id="ErrorLogFormat">ErrorLogFormat</a> <a name="errorlogformat" id="errorlogformat">Directive</a></h2>
1507 <table class="directive">
1508 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Format specification for error log entries</td></tr>
1509 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code> ErrorLogFormat [connection|request] <var>format</var></code></td></tr>
1510 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1511 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1512 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1514 <p><code class="directive">ErrorLogFormat</code> allows to specify what
1515 supplementary information is logged in the error log in addition to the
1516 actual log message.</p>
1518 <pre class="prettyprint lang-config">#Simple example
1519 ErrorLogFormat "[%t] [%l] [pid %P] %F: %E: [client %a] %M"</pre>
1522 <p>Specifying <code>connection</code> or <code>request</code> as first
1523 parameter allows to specify additional formats, causing additional
1524 information to be logged when the first message is logged for a specific
1525 connection or request, respectively. This additional information is only
1526 logged once per connection/request. If a connection or request is processed
1527 without causing any log message, the additional information is not logged
1530 <p>It can happen that some format string items do not produce output. For
1531 example, the Referer header is only present if the log message is
1532 associated to a request and the log message happens at a time when the
1533 Referer header has already been read from the client. If no output is
1534 produced, the default behavior is to delete everything from the preceding
1535 space character to the next space character. This means the log line is
1536 implicitly divided into fields on non-whitespace to whitespace transitions.
1537 If a format string item does not produce output, the whole field is
1538 omitted. For example, if the remote address <code>%a</code> in the log
1539 format <code>[%t] [%l] [%a] %M </code> is not available, the surrounding
1540 brackets are not logged either. Space characters can be escaped with a
1541 backslash to prevent them from delimiting a field. The combination '% '
1542 (percent space) is a zero-width field delimiter that does not produce any
1545 <p>The above behavior can be changed by adding modifiers to the format
1546 string item. A <code>-</code> (minus) modifier causes a minus to be logged if the
1547 respective item does not produce any output. In once-per-connection/request
1548 formats, it is also possible to use the <code>+</code> (plus) modifier. If an
1549 item with the plus modifier does not produce any output, the whole line is
1552 <p>A number as modifier can be used to assign a log severity level to a
1553 format item. The item will only be logged if the severity of the log
1554 message is not higher than the specified log severity level. The number can
1555 range from 1 (alert) over 4 (warn) and 7 (debug) to 15 (trace8).</p>
1557 <p>For example, here's what would happen if you added modifiers to
1558 the <code>%{Referer}i</code> token, which logs the
1559 <code>Referer</code> request header.</p>
1561 <table class="bordered"><tr class="header"><th>Modified Token</th><th>Meaning</th></tr>
1563 <td><code>%-{Referer}i</code></td>
1564 <td>Logs a <code>-</code> if <code>Referer</code> is not set.</td>
1567 <td><code>%+{Referer}i</code></td>
1568 <td>Omits the entire line if <code>Referer</code> is not set.</td>
1571 <td><code>%4{Referer}i</code></td>
1572 <td>Logs the <code>Referer</code> only if the log message severity
1573 is higher than 4.</td>
1577 <p>Some format string items accept additional parameters in braces.</p>
1579 <table class="bordered"><tr class="header"><th>Format String</th> <th>Description</th></tr>
1580 <tr><td><code>%%</code></td>
1581 <td>The percent sign</td></tr>
1582 <tr class="odd"><td><code>%a</code></td>
1583 <td>Client IP address and port of the request</td></tr>
1584 <tr><td><code>%{c}a</code></td>
1585 <td>Underlying peer IP address and port of the connection (see the
1586 <code class="module"><a href="../mod/mod_remoteip.html">mod_remoteip</a></code> module)</td></tr>
1587 <tr class="odd"><td><code>%A</code></td>
1588 <td>Local IP-address and port</td></tr>
1589 <tr><td><code>%{<em>name</em>}e</code></td>
1590 <td>Request environment variable <em>name</em></td></tr>
1591 <tr class="odd"><td><code>%E</code></td>
1592 <td>APR/OS error status code and string</td></tr>
1593 <tr><td><code>%F</code></td>
1594 <td>Source file name and line number of the log call</td></tr>
1595 <tr class="odd"><td><code>%{<em>name</em>}i</code></td>
1596 <td>Request header <em>name</em></td></tr>
1597 <tr><td><code>%k</code></td>
1598 <td>Number of keep-alive requests on this connection</td></tr>
1599 <tr class="odd"><td><code>%l</code></td>
1600 <td>Loglevel of the message</td></tr>
1601 <tr><td><code>%L</code></td>
1602 <td>Log ID of the request</td></tr>
1603 <tr class="odd"><td><code>%{c}L</code></td>
1604 <td>Log ID of the connection</td></tr>
1605 <tr><td><code>%{C}L</code></td>
1606 <td>Log ID of the connection if used in connection scope, empty otherwise</td></tr>
1607 <tr class="odd"><td><code>%m</code></td>
1608 <td>Name of the module logging the message</td></tr>
1609 <tr><td><code>%M</code></td>
1610 <td>The actual log message</td></tr>
1611 <tr class="odd"><td><code>%{<em>name</em>}n</code></td>
1612 <td>Request note <em>name</em></td></tr>
1613 <tr><td><code>%P</code></td>
1614 <td>Process ID of current process</td></tr>
1615 <tr class="odd"><td><code>%T</code></td>
1616 <td>Thread ID of current thread</td></tr>
1617 <tr><td><code>%{g}T</code></td>
1618 <td>System unique thread ID of current thread (the same ID as
1619 displayed by e.g. <code>top</code>; currently Linux only)</td></tr>
1620 <tr class="odd"><td><code>%t</code></td>
1621 <td>The current time</td></tr>
1622 <tr><td><code>%{u}t</code></td>
1623 <td>The current time including micro-seconds</td></tr>
1624 <tr class="odd"><td><code>%{cu}t</code></td>
1625 <td>The current time in compact ISO 8601 format, including
1626 micro-seconds</td></tr>
1627 <tr><td><code>%v</code></td>
1628 <td>The canonical <code class="directive"><a href="#servername">ServerName</a></code>
1629 of the current server.</td></tr>
1630 <tr class="odd"><td><code>%V</code></td>
1631 <td>The server name of the server serving the request according to the
1632 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code>
1634 <tr><td><code>\ </code> (backslash space)</td>
1635 <td>Non-field delimiting space</td></tr>
1636 <tr class="odd"><td><code>% </code> (percent space)</td>
1637 <td>Field delimiter (no output)</td></tr>
1640 <p>The log ID format <code>%L</code> produces a unique id for a connection
1641 or request. This can be used to correlate which log lines belong to the
1642 same connection or request, which request happens on which connection.
1643 A <code>%L</code> format string is also available in
1644 <code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code> to allow to correlate access log entries
1645 with error log lines. If <code class="module"><a href="../mod/mod_unique_id.html">mod_unique_id</a></code> is loaded, its
1646 unique id will be used as log ID for requests.</p>
1648 <pre class="prettyprint lang-config">#Example (default format for threaded MPMs)
1649 ErrorLogFormat "[%{u}t] [%-m:%l] [pid %P:tid %T] %7F: %E: [client\ %a] %M% ,\ referer\ %{Referer}i"</pre>
1652 <p>This would result in error messages such as:</p>
1654 <div class="example"><p><code>
1655 [Thu May 12 08:28:57.652118 2011] [core:error] [pid 8777:tid 4326490112] [client ::1:58619] File does not exist: /usr/local/apache2/htdocs/favicon.ico
1658 <p>Notice that, as discussed above, some fields are omitted
1659 entirely because they are not defined.</p>
1661 <pre class="prettyprint lang-config">#Example (similar to the 2.2.x format)
1662 ErrorLogFormat "[%t] [%l] %7F: %E: [client\ %a] %M% ,\ referer\ %{Referer}i"</pre>
1665 <pre class="prettyprint lang-config">#Advanced example with request/connection log IDs
1666 ErrorLogFormat "[%{uc}t] [%-m:%-l] [R:%L] [C:%{C}L] %7F: %E: %M"
1667 ErrorLogFormat request "[%{uc}t] [R:%L] Request %k on C:%{c}L pid:%P tid:%T"
1668 ErrorLogFormat request "[%{uc}t] [R:%L] UA:'%+{User-Agent}i'"
1669 ErrorLogFormat request "[%{uc}t] [R:%L] Referer:'%+{Referer}i'"
1670 ErrorLogFormat connection "[%{uc}t] [C:%{c}L] local\ %a remote\ %A"</pre>
1676 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
1677 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1678 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1681 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1682 <div class="directive-section"><h2><a name="ExtendedStatus" id="ExtendedStatus">ExtendedStatus</a> <a name="extendedstatus" id="extendedstatus">Directive</a></h2>
1683 <table class="directive">
1684 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Keep track of extended status information for each
1686 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ExtendedStatus On|Off</code></td></tr>
1687 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ExtendedStatus Off[*]</code></td></tr>
1688 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
1689 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1690 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1692 <p>This option tracks additional data per worker about the
1693 currently executing request and creates a utilization summary.
1694 You can see these variables during runtime by configuring
1695 <code class="module"><a href="../mod/mod_status.html">mod_status</a></code>. Note that other modules may
1696 rely on this scoreboard.</p>
1698 <p>This setting applies to the entire server and cannot be
1699 enabled or disabled on a virtualhost-by-virtualhost basis.
1700 The collection of extended status information can slow down
1701 the server. Also note that this setting cannot be changed
1702 during a graceful restart.</p>
1705 <p>Note that loading <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> will change
1706 the default behavior to ExtendedStatus On, while other
1707 third party modules may do the same. Such modules rely on
1708 collecting detailed information about the state of all workers.
1709 The default is changed by <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> beginning
1710 with version 2.3.6. The previous default was always Off.</p>
1715 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1716 <div class="directive-section"><h2><a name="FileETag" id="FileETag">FileETag</a> <a name="fileetag" id="fileetag">Directive</a></h2>
1717 <table class="directive">
1718 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>File attributes used to create the ETag
1719 HTTP response header for static files</td></tr>
1720 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>FileETag <var>component</var> ...</code></td></tr>
1721 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>FileETag MTime Size</code></td></tr>
1722 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1723 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1724 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1725 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1726 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The default used to be "INode MTime Size" in 2.3.14 and
1730 The <code class="directive">FileETag</code> directive configures the file
1731 attributes that are used to create the <code>ETag</code> (entity
1732 tag) response header field when the document is based on a static file.
1733 (The <code>ETag</code> value is used in cache management to save
1734 network bandwidth.) The
1735 <code class="directive">FileETag</code> directive allows you to choose
1736 which of these -- if any -- should be used. The recognized keywords are:
1740 <dt><strong>INode</strong></dt>
1741 <dd>The file's i-node number will be included in the calculation</dd>
1742 <dt><strong>MTime</strong></dt>
1743 <dd>The date and time the file was last modified will be included</dd>
1744 <dt><strong>Size</strong></dt>
1745 <dd>The number of bytes in the file will be included</dd>
1746 <dt><strong>All</strong></dt>
1747 <dd>All available fields will be used. This is equivalent to:
1748 <pre class="prettyprint lang-config">FileETag INode MTime Size</pre>
1750 <dt><strong>None</strong></dt>
1751 <dd>If a document is file-based, no <code>ETag</code> field will be
1752 included in the response</dd>
1755 <p>The <code>INode</code>, <code>MTime</code>, and <code>Size</code>
1756 keywords may be prefixed with either <code>+</code> or <code>-</code>,
1757 which allow changes to be made to the default setting inherited
1758 from a broader scope. Any keyword appearing without such a prefix
1759 immediately and completely cancels the inherited setting.</p>
1761 <p>If a directory's configuration includes
1762 <code>FileETag INode MTime Size</code>, and a
1763 subdirectory's includes <code>FileETag -INode</code>,
1764 the setting for that subdirectory (which will be inherited by
1765 any sub-subdirectories that don't override it) will be equivalent to
1766 <code>FileETag MTime Size</code>.</p>
1767 <div class="warning"><h3>Warning</h3>
1768 Do not change the default for directories or locations that have WebDAV
1769 enabled and use <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> as a storage provider.
1770 <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> uses <code>MTime Size</code>
1771 as a fixed format for <code>ETag</code> comparisons on conditional requests.
1772 These conditional requests will break if the <code>ETag</code> format is
1773 changed via <code class="directive">FileETag</code>.
1775 <div class="note"><h3>Server Side Includes</h3>
1776 An ETag is not generated for responses parsed by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
1777 since the response entity can change without a change of the INode, MTime, or Size
1778 of the static file with embedded SSI directives.
1783 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1784 <div class="directive-section"><h2><a name="Files" id="Files"><Files></a> <a name="files" id="files">Directive</a></h2>
1785 <table class="directive">
1786 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to matched
1788 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Files <var>filename</var>> ... </Files></code></td></tr>
1789 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1790 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1791 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1792 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1794 <p>The <code class="directive"><Files></code> directive
1795 limits the scope of the enclosed directives by filename. It is comparable
1796 to the <code class="directive"><a href="#directory"><Directory></a></code>
1797 and <code class="directive"><a href="#location"><Location></a></code>
1798 directives. It should be matched with a <code></Files></code>
1799 directive. The directives given within this section will be applied to
1800 any object with a basename (last component of filename) matching the
1801 specified filename. <code class="directive"><Files></code>
1802 sections are processed in the order they appear in the
1803 configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
1804 <code>.htaccess</code> files are read, but before <code class="directive"><a href="#location"><Location></a></code> sections. Note
1805 that <code class="directive"><Files></code> can be nested
1806 inside <code class="directive"><a href="#directory"><Directory></a></code> sections to restrict the
1807 portion of the filesystem they apply to.</p>
1809 <p>The <var>filename</var> argument should include a filename, or
1810 a wild-card string, where <code>?</code> matches any single character,
1811 and <code>*</code> matches any sequences of characters.</p>
1812 <pre class="prettyprint lang-config"><Files "cat.html">
1813 # Insert stuff that applies to cat.html here
1816 <Files "?at.*">
1817 # This would apply to cat.html, bat.html, hat.php and so on.
1818 </Files></pre>
1820 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
1821 can also be used, with the addition of the
1822 <code>~</code> character. For example:</p>
1824 <pre class="prettyprint lang-config"><Files ~ "\.(gif|jpe?g|png)$">
1826 </Files></pre>
1829 <p>would match most common Internet graphics formats. <code class="directive"><a href="#filesmatch"><FilesMatch></a></code> is preferred,
1832 <p>Note that unlike <code class="directive"><a href="#directory"><Directory></a></code> and <code class="directive"><a href="#location"><Location></a></code> sections, <code class="directive"><Files></code> sections can be used inside
1833 <code>.htaccess</code> files. This allows users to control access to
1834 their own files, at a file-by-file level.</p>
1839 <li><a href="../sections.html">How <Directory>, <Location>
1840 and <Files> sections work</a> for an explanation of how these
1841 different sections are combined when a request is received</li>
1844 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1845 <div class="directive-section"><h2><a name="FilesMatch" id="FilesMatch"><FilesMatch></a> <a name="filesmatch" id="filesmatch">Directive</a></h2>
1846 <table class="directive">
1847 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to regular-expression matched
1849 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><FilesMatch <var>regex</var>> ... </FilesMatch></code></td></tr>
1850 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1851 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1852 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1853 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1855 <p>The <code class="directive"><FilesMatch></code> directive
1856 limits the scope of the enclosed directives by filename, just as the
1857 <code class="directive"><a href="#files"><Files></a></code> directive
1858 does. However, it accepts a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular
1859 expression</a>. For example:</p>
1861 <pre class="prettyprint lang-config"><FilesMatch ".+\.(gif|jpe?g|png)$">
1863 </FilesMatch></pre>
1866 <p>would match most common Internet graphics formats.</p>
1868 <div class="note">The <code>.+</code> at the start of the regex ensures that
1869 files named <code>.png</code>, or <code>.gif</code>, for example,
1870 are not matched.</div>
1872 <p>From 2.4.8 onwards, named groups and backreferences are captured and
1873 written to the environment with the corresponding name prefixed with
1874 "MATCH_" and in upper case. This allows elements of files to be referenced
1875 from within <a href="../expr.html">expressions</a> and modules like
1876 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
1877 (unnamed) backreferences are ignored. Use named groups instead.</p>
1879 <pre class="prettyprint lang-config"><FilesMatch "^(?<sitename>[^/]+)">
1880 require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
1881 </FilesMatch></pre>
1886 <li><a href="../sections.html">How <Directory>, <Location>
1887 and <Files> sections work</a> for an explanation of how these
1888 different sections are combined when a request is received</li>
1891 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1892 <div class="directive-section"><h2><a name="ForceType" id="ForceType">ForceType</a> <a name="forcetype" id="forcetype">Directive</a></h2>
1893 <table class="directive">
1894 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be served with the specified
1895 media type in the HTTP Content-Type header field</td></tr>
1896 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ForceType <var>media-type</var>|None</code></td></tr>
1897 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
1898 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1899 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1900 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1902 <p>When placed into an <code>.htaccess</code> file or a
1903 <code class="directive"><a href="#directory"><Directory></a></code>, or
1904 <code class="directive"><a href="#location"><Location></a></code> or
1905 <code class="directive"><a href="#files"><Files></a></code>
1906 section, this directive forces all matching files to be served
1907 with the content type identification given by
1908 <var>media-type</var>. For example, if you had a directory full of
1909 GIF files, but did not want to label them all with <code>.gif</code>,
1910 you might want to use:</p>
1912 <pre class="prettyprint lang-config">ForceType image/gif</pre>
1915 <p>Note that this directive overrides other indirect media type
1916 associations defined in mime.types or via the
1917 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code>.</p>
1919 <p>You can also override more general
1920 <code class="directive">ForceType</code> settings
1921 by using the value of <code>None</code>:</p>
1923 <pre class="prettyprint lang-config"># force all files to be image/gif:
1924 <Location "/images">
1928 # but normal mime-type associations here:
1929 <Location "/images/mixed">
1931 </Location></pre>
1934 <p>This directive primarily overrides the content types generated for
1935 static files served out of the filesystem. For resources other than
1936 static files, where the generator of the response typically specifies
1937 a Content-Type, this directive has no effect.</p>
1940 <div class="note"><h3>Note</h3>
1941 <p>If no handler is explicitly set for a request, the specified content
1942 type will also be used as the handler name. </p>
1944 <p>When explicit directives such as
1945 <code class="directive"><a href="#sethandler">SetHandler</a></code> or
1946 <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> do not apply
1947 to the current request, the internal handler name normally set by those
1948 directives is instead set to the content type specified by this directive.
1951 This is a historical behavior that some third-party modules
1952 (such as mod_php) may look for a "synthetic" content type used only to
1953 signal the module to take responsibility for the matching request.
1956 <p>Configurations that rely on such "synthetic" types should be avoided.
1957 Additionally, configurations that restrict access to
1958 <code class="directive"><a href="#sethandler">SetHandler</a></code> or
1959 <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> should
1960 restrict access to this directive as well.</p>
1965 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1966 <div class="directive-section"><h2><a name="GprofDir" id="GprofDir">GprofDir</a> <a name="gprofdir" id="gprofdir">Directive</a></h2>
1967 <table class="directive">
1968 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory to write gmon.out profiling data to. </td></tr>
1969 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>GprofDir <var>/tmp/gprof/</var>|<var>/tmp/gprof/</var>%</code></td></tr>
1970 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1971 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1972 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1974 <p>When the server has been compiled with gprof profiling support,
1975 <code class="directive">GprofDir</code> causes <code>gmon.out</code> files to
1976 be written to the specified directory when the process exits. If the
1977 argument ends with a percent symbol ('%'), subdirectories are created
1978 for each process id.</p>
1980 <p>This directive currently only works with the <code class="module"><a href="../mod/prefork.html">prefork</a></code>
1984 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1985 <div class="directive-section"><h2><a name="HostnameLookups" id="HostnameLookups">HostnameLookups</a> <a name="hostnamelookups" id="hostnamelookups">Directive</a></h2>
1986 <table class="directive">
1987 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables DNS lookups on client IP addresses</td></tr>
1988 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HostnameLookups On|Off|Double</code></td></tr>
1989 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HostnameLookups Off</code></td></tr>
1990 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1991 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1992 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1994 <p>This directive enables DNS lookups so that host names can be
1995 logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
1996 The value <code>Double</code> refers to doing double-reverse
1997 DNS lookup. That is, after a reverse lookup is performed, a forward
1998 lookup is then performed on that result. At least one of the IP
1999 addresses in the forward lookup must match the original
2000 address. (In "tcpwrappers" terminology this is called
2001 <code>PARANOID</code>.)</p>
2003 <p>Regardless of the setting, when <code class="module"><a href="../mod/mod_authz_host.html">mod_authz_host</a></code> is
2004 used for controlling access by hostname, a double reverse lookup
2005 will be performed. This is necessary for security. Note that the
2006 result of this double-reverse isn't generally available unless you
2007 set <code>HostnameLookups Double</code>. For example, if only
2008 <code>HostnameLookups On</code> and a request is made to an object
2009 that is protected by hostname restrictions, regardless of whether
2010 the double-reverse fails or not, CGIs will still be passed the
2011 single-reverse result in <code>REMOTE_HOST</code>.</p>
2013 <p>The default is <code>Off</code> in order to save the network
2014 traffic for those sites that don't truly need the reverse
2015 lookups done. It is also better for the end users because they
2016 don't have to suffer the extra latency that a lookup entails.
2017 Heavily loaded sites should leave this directive
2018 <code>Off</code>, since DNS lookups can take considerable
2019 amounts of time. The utility <code class="program"><a href="../programs/logresolve.html">logresolve</a></code>, compiled by
2020 default to the <code>bin</code> subdirectory of your installation
2021 directory, can be used to look up host names from logged IP addresses
2024 <p>Finally, if you have <a href="mod_authz_host.html#reqhost">hostname-based Require
2025 directives</a>, a hostname lookup will be performed regardless of
2026 the setting of <code>HostnameLookups</code>.</p>
2029 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2030 <div class="directive-section"><h2><a name="HttpProtocolOptions" id="HttpProtocolOptions">HttpProtocolOptions</a> <a name="httpprotocoloptions" id="httpprotocoloptions">Directive</a></h2>
2031 <table class="directive">
2032 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Modify restrictions on HTTP Request Messages</td></tr>
2033 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HttpProtocolOptions [Strict|Unsafe] [StrictURL|UnsafeURL]
2034 [StrictWhitespace|LenientWhitespace] [RegisteredMethods|LenientMethods]
2035 [Allow0.9|Require1.0]</code></td></tr>
2036 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HttpProtocolOptions Strict StrictURL LenientWhitespace
2037 LenientMethods Allow0.9</code></td></tr>
2038 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2039 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2040 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2041 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.2.32 or 2.4.24 and later</td></tr>
2043 <p>This directive changes the rules applied to the HTTP Request Line
2044 (<a href="https://tools.ietf.org/html/rfc7230#section-3.1.1">RFC 7230 §3.1.1</a>) and the HTTP Request Header Fields
2045 (<a href="https://tools.ietf.org/html/rfc7230#section-3.2">RFC 7230 §3.2</a>), which are now applied by default or using
2046 the <code>Strict</code> option. Due to legacy modules, applications or
2047 custom user-agents which must be deperecated, <code>Unsafe</code>
2048 and <code>UnsafeURL</code> options have been added to revert to the legacy
2049 behaviors. These rules are applied prior to request processing, so must be
2050 configured at the global or default (first) matching virtual host section,
2051 by IP/port interface and not by name, to be honored.</p>
2053 <p>Prior to the introduction of this directive, the Apache HTTP Server
2054 request message parsers were tolerant of a number of forms of input
2055 which did not conform to the protocol.
2056 <a href="https://tools.ietf.org/html/rfc7230#section-9.4">RFC 7230 §9.4 Request Splitting</a> and
2057 <a href="https://tools.ietf.org/html/rfc7230#section-9.5">§9.5 Response Smuggling</a> call out only two of the potential
2058 risks of accepting non-conformant request messages. As of the introduction
2059 of this directive, all grammer rules of the specification are enforced in
2060 the default <code>Strict</code> operating mode.</p>
2062 <p><a href="https://tools.ietf.org/html/rfc3986#section-2.2">RFC 7230 §2.2 and 2.3</a> define "Reserved Characters" and
2063 "Unreserved Characters". All other character octets are required to
2064 be %XX encoded under this spec, and RFC7230 defers to these requirements.
2065 By default the <code>StrictURI</code> option will reject all requests
2066 containing invalid characters. This rule can be relaxed with the
2067 <code>UnsafeURI</code> option to support badly written user-agents.</p>
2069 <p>Users are strongly cautioned against toggling the <code>Unsafe</code>
2070 and <code>UnsafeURI</code> modes of operation, most especially on
2071 outward-facing, publicly accessible server deployments. If an interface
2072 is required of faulty monitoring or other custom software running only
2073 on an intranet, users should consider toggling these only for a specific
2074 virtual host configured on their private subnet.</p>
2076 <p>Reviewing the messages logged to the <code class="directive">ErrorLog</code>,
2077 configured with <code class="directive">LogLevel</code> <code>info</code> level,
2078 can help identify such faulty requests along with their origin.
2079 Users should pay particular attention to any 400 responses in the access
2080 log for indiciations that valid requests are unexpectedly rejected.</p>
2082 <p><a href="https://tools.ietf.org/html/rfc7230#section-3.5">RFC 7230 §3.5</a> "Message Parsing Robustness" permits, and
2083 identifies potential risks of parsing messages containing non-space
2084 character whitespace. While the spec defines that exactly one space
2085 seperates the URI from the method, and the protocol from the URI, the
2086 Apache HTTP Server has traditionally been lenient in accepting other
2087 whitespace including one or more horizontal-tab or space characters.
2088 The default <code>LenientWhitespace</code> continues to accept such
2089 requests from non-conforming user-agents, but the administrator may toggle
2090 the <code>StrictWhitespace</code> option to insist on precisely two spaces
2091 in the request line. Other whitespace including vertical-tab, form-feed,
2092 and carriage-return characters are rejected and cannot be supported.</p>
2094 <p><a href="https://tools.ietf.org/html/rfc7231#section-4.1">RFC 7231 §4.1</a> "Request Methods" "Overview" requires that
2095 origin servers shall respond with an error when an unsupported method
2096 is encountered in the request line. This already happens when the
2097 <code>LenientMethods</code> option is used, but administrators may wish
2098 to toggle the <code>RegisteredMethods</code> option and register any
2099 non-standard methods using the <code class="directive">RegisterHttpMethod</code>
2100 directive, particularly if the <code>Unsafe</code> option has been toggled.
2101 The <code>RegisteredMethods</code> option should <strong>not</strong>
2102 be toggled for forward proxy hosts, as the methods supported by the
2103 origin servers are unknown to the proxy server.</p>
2105 <p><a href="https://tools.ietf.org/html/rfc2616#section-19.6">RFC 2616 §19.6</a> "Compatibility With Previous Versions" had
2106 encouraged HTTP servers to support legacy HTTP/0.9 requests. RFC 7230
2107 superceeds this with "The expectation to support HTTP/0.9 requests has
2108 been removed" and offers additional comments in
2109 <a href="https://tools.ietf.org/html/rfc7230#appendix-A">RFC 2616 Appendix A</a>. The <code>Require1.0</code> option allows
2110 the user to remove support of the default <code>Allow0.9</code> option's
2114 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2115 <div class="directive-section"><h2><a name="If" id="If"><If></a> <a name="if" id="if">Directive</a></h2>
2116 <table class="directive">
2117 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is
2118 satisfied by a request at runtime</td></tr>
2119 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><If <var>expression</var>> ... </If></code></td></tr>
2120 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2121 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2122 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2123 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2125 <p>The <code class="directive"><If></code> directive
2126 evaluates an expression at runtime, and applies the enclosed
2127 directives if and only if the expression evaluates to true.
2130 <pre class="prettyprint lang-config"><If "-z req('Host')"></pre>
2133 <p>would match HTTP/1.0 requests without a <var>Host:</var> header.
2134 Expressions may contain various shell-like operators for string
2135 comparison (<code>==</code>, <code>!=</code>, <code><</code>, ...),
2136 integer comparison (<code>-eq</code>, <code>-ne</code>, ...),
2137 and others (<code>-n</code>, <code>-z</code>, <code>-f</code>, ...).
2138 It is also possible to use regular expressions, </p>
2140 <pre class="prettyprint lang-config"><If "%{QUERY_STRING} =~ /(delete|commit)=.*?elem/"></pre>
2143 <p>shell-like pattern matches and many other operations. These operations
2144 can be done on request headers (<code>req</code>), environment variables
2145 (<code>env</code>), and a large number of other properties. The full
2146 documentation is available in <a href="../expr.html">Expressions in
2147 Apache HTTP Server</a>.</p>
2149 <p>Only directives that support the <a href="directive-dict.html#Context">directory context</a> can be used within this configuration section.</p>
2151 <div class="warning">
2152 Certain variables, such as <code>CONTENT_TYPE</code> and other
2153 response headers, are set after <If> conditions have already
2154 been evaluated, and so will not be available to use in this
2161 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
2162 for a complete reference and more examples.</li>
2163 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
2164 <li><code class="directive"><a href="#else"><Else></a></code></li>
2165 <li><a href="../sections.html">How <Directory>, <Location>,
2166 <Files> sections work</a> for an explanation of how these
2167 different sections are combined when a request is received.
2168 <code class="directive"><If></code>,
2169 <code class="directive"><ElseIf></code>, and
2170 <code class="directive"><Else></code> are applied last.</li>
2173 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2174 <div class="directive-section"><h2><a name="IfDefine" id="IfDefine"><IfDefine></a> <a name="ifdefine" id="ifdefine">Directive</a></h2>
2175 <table class="directive">
2176 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that will be processed only
2177 if a test is true at startup</td></tr>
2178 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfDefine [!]<var>parameter-name</var>> ...
2179 </IfDefine></code></td></tr>
2180 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2181 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2182 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2183 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2185 <p>The <code><IfDefine <var>test</var>>...</IfDefine>
2186 </code> section is used to mark directives that are conditional. The
2187 directives within an <code class="directive"><IfDefine></code>
2188 section are only processed if the <var>test</var> is true. If <var>
2189 test</var> is false, everything between the start and end markers is
2192 <p>The <var>test</var> in the <code class="directive"><IfDefine></code> section directive can be one of two forms:</p>
2195 <li><var>parameter-name</var></li>
2197 <li><code>!</code><var>parameter-name</var></li>
2200 <p>In the former case, the directives between the start and end
2201 markers are only processed if the parameter named
2202 <var>parameter-name</var> is defined. The second format reverses
2203 the test, and only processes the directives if
2204 <var>parameter-name</var> is <strong>not</strong> defined.</p>
2206 <p>The <var>parameter-name</var> argument is a define as given on the
2207 <code class="program"><a href="../programs/httpd.html">httpd</a></code> command line via <code>-D<var>parameter</var>
2208 </code> at the time the server was started or by the <code class="directive"><a href="#define">Define</a></code> directive.</p>
2210 <p><code class="directive"><IfDefine></code> sections are
2211 nest-able, which can be used to implement simple
2212 multiple-parameter tests. Example:</p>
2214 <div class="example"><p><code>httpd -DReverseProxy -DUseCache -DMemCache ...</code></p></div>
2215 <pre class="prettyprint lang-config"><IfDefine ReverseProxy>
2216 LoadModule proxy_module modules/mod_proxy.so
2217 LoadModule proxy_http_module modules/mod_proxy_http.so
2218 <IfDefine UseCache>
2219 LoadModule cache_module modules/mod_cache.so
2220 <IfDefine MemCache>
2221 LoadModule mem_cache_module modules/mod_mem_cache.so
2223 <IfDefine !MemCache>
2224 LoadModule cache_disk_module modules/mod_cache_disk.so
2227 </IfDefine></pre>
2231 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2232 <div class="directive-section"><h2><a name="IfModule" id="IfModule"><IfModule></a> <a name="ifmodule" id="ifmodule">Directive</a></h2>
2233 <table class="directive">
2234 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that are processed conditional on the
2235 presence or absence of a specific module</td></tr>
2236 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfModule [!]<var>module-file</var>|<var>module-identifier</var>> ...
2237 </IfModule></code></td></tr>
2238 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2239 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2240 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2241 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2243 <p>The <code><IfModule <var>test</var>>...</IfModule></code>
2244 section is used to mark directives that are conditional on the presence of
2245 a specific module. The directives within an <code class="directive"><IfModule></code> section are only processed if the <var>test</var>
2246 is true. If <var>test</var> is false, everything between the start and
2247 end markers is ignored.</p>
2249 <p>The <var>test</var> in the <code class="directive"><IfModule></code> section directive can be one of two forms:</p>
2252 <li><var>module</var></li>
2254 <li>!<var>module</var></li>
2257 <p>In the former case, the directives between the start and end
2258 markers are only processed if the module named <var>module</var>
2259 is included in Apache httpd -- either compiled in or
2260 dynamically loaded using <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code>. The second format reverses the test,
2261 and only processes the directives if <var>module</var> is
2262 <strong>not</strong> included.</p>
2264 <p>The <var>module</var> argument can be either the module identifier or
2265 the file name of the module, at the time it was compiled. For example,
2266 <code>rewrite_module</code> is the identifier and
2267 <code>mod_rewrite.c</code> is the file name. If a module consists of
2268 several source files, use the name of the file containing the string
2269 <code>STANDARD20_MODULE_STUFF</code>.</p>
2271 <p><code class="directive"><IfModule></code> sections are
2272 nest-able, which can be used to implement simple multiple-module
2275 <div class="note">This section should only be used if you need to have one
2276 configuration file that works whether or not a specific module
2277 is available. In normal operation, directives need not be
2278 placed in <code class="directive"><IfModule></code>
2282 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2283 <div class="directive-section"><h2><a name="Include" id="Include">Include</a> <a name="include" id="include">Directive</a></h2>
2284 <table class="directive">
2285 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2286 the server configuration files</td></tr>
2287 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Include <var>file-path</var>|<var>directory-path</var>|<var>wildcard</var></code></td></tr>
2288 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2289 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2290 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2291 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directory
2292 wildcard matching available in 2.3.6 and later</td></tr>
2294 <p>This directive allows inclusion of other configuration files
2295 from within the server configuration files.</p>
2297 <p>Shell-style (<code>fnmatch()</code>) wildcard characters can be used
2298 in the filename or directory parts of the path to include several files
2299 at once, in alphabetical order. In addition, if
2300 <code class="directive">Include</code> points to a directory, rather than a file,
2301 Apache httpd will read all files in that directory and any subdirectory.
2302 However, including entire directories is not recommended, because it is
2303 easy to accidentally leave temporary files in a directory that can cause
2304 <code class="program"><a href="../programs/httpd.html">httpd</a></code> to fail. Instead, we encourage you to use the
2305 wildcard syntax shown below, to include files that match a particular
2306 pattern, such as *.conf, for example.</p>
2308 <p>The <code class="directive"><a href="#include">Include</a></code> directive will
2309 <strong>fail with an error</strong> if a wildcard expression does not
2310 match any file. The <code class="directive"><a href="#includeoptional">IncludeOptional</a></code>
2311 directive can be used if non-matching wildcards should be ignored.</p>
2313 <p>The file path specified may be an absolute path, or may be relative
2314 to the <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory.</p>
2318 <pre class="prettyprint lang-config">Include /usr/local/apache2/conf/ssl.conf
2319 Include /usr/local/apache2/conf/vhosts/*.conf</pre>
2322 <p>Or, providing paths relative to your <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory:</p>
2324 <pre class="prettyprint lang-config">Include conf/ssl.conf
2325 Include conf/vhosts/*.conf</pre>
2328 <p>Wildcards may be included in the directory or file portion of the
2329 path. This example will fail if there is no subdirectory in conf/vhosts
2330 that contains at least one *.conf file:</p>
2332 <pre class="prettyprint lang-config">Include conf/vhosts/*/*.conf</pre>
2335 <p>Alternatively, the following command will just be ignored in case of
2336 missing files or directories:</p>
2338 <pre class="prettyprint lang-config">IncludeOptional conf/vhosts/*/*.conf</pre>
2344 <li><code class="directive"><a href="#includeoptional">IncludeOptional</a></code></li>
2345 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
2348 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2349 <div class="directive-section"><h2><a name="IncludeOptional" id="IncludeOptional">IncludeOptional</a> <a name="includeoptional" id="includeoptional">Directive</a></h2>
2350 <table class="directive">
2351 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2352 the server configuration files</td></tr>
2353 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>IncludeOptional <var>file-path</var>|<var>directory-path</var>|<var>wildcard</var></code></td></tr>
2354 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2355 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2356 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2357 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in 2.3.6 and later</td></tr>
2359 <p>This directive allows inclusion of other configuration files
2360 from within the server configuration files. It works identically to the
2361 <code class="directive"><a href="#include">Include</a></code> directive, with the
2362 exception that if wildcards do not match any file or directory, the
2363 <code class="directive"><a href="#includeoptional">IncludeOptional</a></code> directive will be
2364 silently ignored instead of causing an error.</p>
2368 <li><code class="directive"><a href="#include">Include</a></code></li>
2369 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
2372 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2373 <div class="directive-section"><h2><a name="KeepAlive" id="KeepAlive">KeepAlive</a> <a name="keepalive" id="keepalive">Directive</a></h2>
2374 <table class="directive">
2375 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables HTTP persistent connections</td></tr>
2376 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAlive On|Off</code></td></tr>
2377 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAlive On</code></td></tr>
2378 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2379 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2380 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2382 <p>The Keep-Alive extension to HTTP/1.0 and the persistent
2383 connection feature of HTTP/1.1 provide long-lived HTTP sessions
2384 which allow multiple requests to be sent over the same TCP
2385 connection. In some cases this has been shown to result in an
2386 almost 50% speedup in latency times for HTML documents with
2387 many images. To enable Keep-Alive connections, set
2388 <code>KeepAlive On</code>.</p>
2390 <p>For HTTP/1.0 clients, Keep-Alive connections will only be
2391 used if they are specifically requested by a client. In
2392 addition, a Keep-Alive connection with an HTTP/1.0 client can
2393 only be used when the length of the content is known in
2394 advance. This implies that dynamic content such as CGI output,
2395 SSI pages, and server-generated directory listings will
2396 generally not use Keep-Alive connections to HTTP/1.0 clients.
2397 For HTTP/1.1 clients, persistent connections are the default
2398 unless otherwise specified. If the client requests it, chunked
2399 encoding will be used in order to send content of unknown
2400 length over persistent connections.</p>
2402 <p>When a client uses a Keep-Alive connection, it will be counted
2403 as a single "request" for the <code class="directive"><a href="../mod/mpm_common.html#maxconnectionsperchild">MaxConnectionsPerChild</a></code> directive, regardless
2404 of how many requests are sent using the connection.</p>
2408 <li><code class="directive"><a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></code></li>
2411 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2412 <div class="directive-section"><h2><a name="KeepAliveTimeout" id="KeepAliveTimeout">KeepAliveTimeout</a> <a name="keepalivetimeout" id="keepalivetimeout">Directive</a></h2>
2413 <table class="directive">
2414 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for subsequent
2415 requests on a persistent connection</td></tr>
2416 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAliveTimeout <var>num</var>[ms]</code></td></tr>
2417 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAliveTimeout 5</code></td></tr>
2418 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2419 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2420 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2422 <p>The number of seconds Apache httpd will wait for a subsequent
2423 request before closing the connection. By adding a postfix of ms the
2424 timeout can be also set in milliseconds. Once a request has been
2425 received, the timeout value specified by the
2426 <code class="directive"><a href="#timeout">Timeout</a></code> directive applies.</p>
2428 <p>Setting <code class="directive">KeepAliveTimeout</code> to a high value
2429 may cause performance problems in heavily loaded servers. The
2430 higher the timeout, the more server processes will be kept
2431 occupied waiting on connections with idle clients.</p>
2433 <p>If <code class="directive">KeepAliveTimeout</code> is <strong>not</strong>
2434 set for a name-based virtual host, the value of the first defined
2435 virtual host best matching the local IP and port will be used.</p>
2438 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2439 <div class="directive-section"><h2><a name="Limit" id="Limit"><Limit></a> <a name="limit" id="limit">Directive</a></h2>
2440 <table class="directive">
2441 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict enclosed access controls to only certain HTTP
2443 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Limit <var>method</var> [<var>method</var>] ... > ...
2444 </Limit></code></td></tr>
2445 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2446 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2447 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2448 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2450 <p>Access controls are normally effective for
2451 <strong>all</strong> access methods, and this is the usual
2452 desired behavior. <strong>In the general case, access control
2453 directives should not be placed within a
2454 <code class="directive"><Limit></code> section.</strong></p>
2456 <p>The purpose of the <code class="directive"><Limit></code>
2457 directive is to restrict the effect of the access controls to the
2458 nominated HTTP methods. For all other methods, the access
2459 restrictions that are enclosed in the <code class="directive"><Limit></code> bracket <strong>will have no
2460 effect</strong>. The following example applies the access control
2461 only to the methods <code>POST</code>, <code>PUT</code>, and
2462 <code>DELETE</code>, leaving all other methods unprotected:</p>
2464 <pre class="prettyprint lang-config"><Limit POST PUT DELETE>
2466 </Limit></pre>
2469 <p>The method names listed can be one or more of: <code>GET</code>,
2470 <code>POST</code>, <code>PUT</code>, <code>DELETE</code>,
2471 <code>CONNECT</code>, <code>OPTIONS</code>,
2472 <code>PATCH</code>, <code>PROPFIND</code>, <code>PROPPATCH</code>,
2473 <code>MKCOL</code>, <code>COPY</code>, <code>MOVE</code>,
2474 <code>LOCK</code>, and <code>UNLOCK</code>. <strong>The method name is
2475 case-sensitive.</strong> If <code>GET</code> is used, it will also
2476 restrict <code>HEAD</code> requests. The <code>TRACE</code> method
2477 cannot be limited (see <code class="directive"><a href="#traceenable">TraceEnable</a></code>).</p>
2479 <div class="warning">A <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section should always be
2480 used in preference to a <code class="directive"><Limit></code>
2481 section when restricting access, since a <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section provides protection
2482 against arbitrary methods.</div>
2484 <p>The <code class="directive"><Limit></code> and
2485 <code class="directive"><a href="#limitexcept"><LimitExcept></a></code>
2486 directives may be nested. In this case, each successive level of
2487 <code class="directive"><Limit></code> or <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> directives must
2488 further restrict the set of methods to which access controls apply.</p>
2490 <div class="warning">When using
2491 <code class="directive"><Limit></code> or
2492 <code class="directive"><LimitExcept></code> directives with
2493 the <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directive,
2494 note that the first <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code>
2495 to succeed authorizes the request, regardless of the presence of other
2496 <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directives.</div>
2498 <p>For example, given the following configuration, all users will
2499 be authorized for <code>POST</code> requests, and the
2500 <code>Require group editors</code> directive will be ignored
2503 <pre class="prettyprint lang-config"><LimitExcept GET>
2505 </LimitExcept>
2507 Require group editors
2508 </Limit></pre>
2512 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2513 <div class="directive-section"><h2><a name="LimitExcept" id="LimitExcept"><LimitExcept></a> <a name="limitexcept" id="limitexcept">Directive</a></h2>
2514 <table class="directive">
2515 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict access controls to all HTTP methods
2516 except the named ones</td></tr>
2517 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LimitExcept <var>method</var> [<var>method</var>] ... > ...
2518 </LimitExcept></code></td></tr>
2519 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2520 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2521 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2522 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2524 <p><code class="directive"><LimitExcept></code> and
2525 <code></LimitExcept></code> are used to enclose
2526 a group of access control directives which will then apply to any
2527 HTTP access method <strong>not</strong> listed in the arguments;
2528 i.e., it is the opposite of a <code class="directive"><a href="#limit"><Limit></a></code> section and can be used to control
2529 both standard and nonstandard/unrecognized methods. See the
2530 documentation for <code class="directive"><a href="#limit"><Limit></a></code> for more details.</p>
2534 <pre class="prettyprint lang-config"><LimitExcept POST GET>
2536 </LimitExcept></pre>
2541 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2542 <div class="directive-section"><h2><a name="LimitInternalRecursion" id="LimitInternalRecursion">LimitInternalRecursion</a> <a name="limitinternalrecursion" id="limitinternalrecursion">Directive</a></h2>
2543 <table class="directive">
2544 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine maximum number of internal redirects and nested
2545 subrequests</td></tr>
2546 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitInternalRecursion <var>number</var> [<var>number</var>]</code></td></tr>
2547 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitInternalRecursion 10</code></td></tr>
2548 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2549 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2550 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2552 <p>An internal redirect happens, for example, when using the <code class="directive"><a href="../mod/mod_actions.html#action">Action</a></code> directive, which internally
2553 redirects the original request to a CGI script. A subrequest is Apache httpd's
2554 mechanism to find out what would happen for some URI if it were requested.
2555 For example, <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> uses subrequests to look for the
2556 files listed in the <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
2559 <p><code class="directive">LimitInternalRecursion</code> prevents the server
2560 from crashing when entering an infinite loop of internal redirects or
2561 subrequests. Such loops are usually caused by misconfigurations.</p>
2563 <p>The directive stores two different limits, which are evaluated on
2564 per-request basis. The first <var>number</var> is the maximum number of
2565 internal redirects that may follow each other. The second <var>number</var>
2566 determines how deeply subrequests may be nested. If you specify only one
2567 <var>number</var>, it will be assigned to both limits.</p>
2569 <pre class="prettyprint lang-config">LimitInternalRecursion 5</pre>
2573 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2574 <div class="directive-section"><h2><a name="LimitRequestBody" id="LimitRequestBody">LimitRequestBody</a> <a name="limitrequestbody" id="limitrequestbody">Directive</a></h2>
2575 <table class="directive">
2576 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restricts the total size of the HTTP request body sent
2577 from the client</td></tr>
2578 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestBody <var>bytes</var></code></td></tr>
2579 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestBody 0</code></td></tr>
2580 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2581 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2582 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2583 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2585 <p>This directive specifies the number of <var>bytes</var> from 0
2586 (meaning unlimited) to 2147483647 (2GB) that are allowed in a
2587 request body. See the note below for the limited applicability
2588 to proxy requests.</p>
2590 <p>The <code class="directive">LimitRequestBody</code> directive allows
2591 the user to set a limit on the allowed size of an HTTP request
2592 message body within the context in which the directive is given
2593 (server, per-directory, per-file or per-location). If the client
2594 request exceeds that limit, the server will return an error
2595 response instead of servicing the request. The size of a normal
2596 request message body will vary greatly depending on the nature of
2597 the resource and the methods allowed on that resource. CGI scripts
2598 typically use the message body for retrieving form information.
2599 Implementations of the <code>PUT</code> method will require
2600 a value at least as large as any representation that the server
2601 wishes to accept for that resource.</p>
2603 <p>This directive gives the server administrator greater
2604 control over abnormal client request behavior, which may be
2605 useful for avoiding some forms of denial-of-service
2608 <p>If, for example, you are permitting file upload to a particular
2609 location and wish to limit the size of the uploaded file to 100K,
2610 you might use the following directive:</p>
2612 <pre class="prettyprint lang-config">LimitRequestBody 102400</pre>
2615 <div class="note"><p>For a full description of how this directive is interpreted by
2616 proxy requests, see the <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> documentation.</p>
2621 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2622 <div class="directive-section"><h2><a name="LimitRequestFields" id="LimitRequestFields">LimitRequestFields</a> <a name="limitrequestfields" id="limitrequestfields">Directive</a></h2>
2623 <table class="directive">
2624 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of HTTP request header fields that
2625 will be accepted from the client</td></tr>
2626 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFields <var>number</var></code></td></tr>
2627 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFields 100</code></td></tr>
2628 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2629 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2630 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2632 <p><var>Number</var> is an integer from 0 (meaning unlimited) to
2633 32767. The default value is defined by the compile-time
2634 constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
2637 <p>The <code class="directive">LimitRequestFields</code> directive allows
2638 the server administrator to modify the limit on the number of
2639 request header fields allowed in an HTTP request. A server needs
2640 this value to be larger than the number of fields that a normal
2641 client request might include. The number of request header fields
2642 used by a client rarely exceeds 20, but this may vary among
2643 different client implementations, often depending upon the extent
2644 to which a user has configured their browser to support detailed
2645 content negotiation. Optional HTTP extensions are often expressed
2646 using request header fields.</p>
2648 <p>This directive gives the server administrator greater
2649 control over abnormal client request behavior, which may be
2650 useful for avoiding some forms of denial-of-service attacks.
2651 The value should be increased if normal clients see an error
2652 response from the server that indicates too many fields were
2653 sent in the request.</p>
2657 <pre class="prettyprint lang-config">LimitRequestFields 50</pre>
2660 <div class="warning"><h3>Warning</h3>
2661 <p> When name-based virtual hosting is used, the value for this
2662 directive is taken from the default (first-listed) virtual host for the
2663 local IP and port combination.</p>
2668 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2669 <div class="directive-section"><h2><a name="LimitRequestFieldSize" id="LimitRequestFieldSize">LimitRequestFieldSize</a> <a name="limitrequestfieldsize" id="limitrequestfieldsize">Directive</a></h2>
2670 <table class="directive">
2671 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of the HTTP request header allowed from the
2673 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFieldSize <var>bytes</var></code></td></tr>
2674 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFieldSize 8190</code></td></tr>
2675 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2676 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2677 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2679 <p>This directive specifies the number of <var>bytes</var>
2680 that will be allowed in an HTTP request header.</p>
2682 <p>The <code class="directive">LimitRequestFieldSize</code> directive
2683 allows the server administrator to set the limit
2684 on the allowed size of an HTTP request header field. A server
2685 needs this value to be large enough to hold any one header field
2686 from a normal client request. The size of a normal request header
2687 field will vary greatly among different client implementations,
2688 often depending upon the extent to which a user has configured
2689 their browser to support detailed content negotiation. SPNEGO
2690 authentication headers can be up to 12392 bytes.</p>
2692 <p>This directive gives the server administrator greater
2693 control over abnormal client request behavior, which may be
2694 useful for avoiding some forms of denial-of-service attacks.</p>
2698 <pre class="prettyprint lang-config">LimitRequestFieldSize 4094</pre>
2701 <div class="note">Under normal conditions, the value should not be changed from
2704 <div class="warning"><h3>Warning</h3>
2705 <p> When name-based virtual hosting is used, the value for this
2706 directive is taken from the default (first-listed) virtual host best
2707 matching the current IP address and port combination.</p>
2711 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2712 <div class="directive-section"><h2><a name="LimitRequestLine" id="LimitRequestLine">LimitRequestLine</a> <a name="limitrequestline" id="limitrequestline">Directive</a></h2>
2713 <table class="directive">
2714 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limit the size of the HTTP request line that will be accepted
2715 from the client</td></tr>
2716 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestLine <var>bytes</var></code></td></tr>
2717 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestLine 8190</code></td></tr>
2718 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2719 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2720 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2722 <p>This directive sets the number of <var>bytes</var> that will be
2723 allowed on the HTTP request-line.</p>
2725 <p>The <code class="directive">LimitRequestLine</code> directive allows
2726 the server administrator to set the limit on the allowed size
2727 of a client's HTTP request-line. Since the request-line consists of the
2728 HTTP method, URI, and protocol version, the
2729 <code class="directive">LimitRequestLine</code> directive places a
2730 restriction on the length of a request-URI allowed for a request
2731 on the server. A server needs this value to be large enough to
2732 hold any of its resource names, including any information that
2733 might be passed in the query part of a <code>GET</code> request.</p>
2735 <p>This directive gives the server administrator greater
2736 control over abnormal client request behavior, which may be
2737 useful for avoiding some forms of denial-of-service attacks.</p>
2741 <pre class="prettyprint lang-config">LimitRequestLine 4094</pre>
2744 <div class="note">Under normal conditions, the value should not be changed from
2747 <div class="warning"><h3>Warning</h3>
2748 <p> When name-based virtual hosting is used, the value for this
2749 directive is taken from the default (first-listed) virtual host best
2750 matching the current IP address and port combination.</p>
2755 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2756 <div class="directive-section"><h2><a name="LimitXMLRequestBody" id="LimitXMLRequestBody">LimitXMLRequestBody</a> <a name="limitxmlrequestbody" id="limitxmlrequestbody">Directive</a></h2>
2757 <table class="directive">
2758 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of an XML-based request body</td></tr>
2759 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitXMLRequestBody <var>bytes</var></code></td></tr>
2760 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitXMLRequestBody 1000000</code></td></tr>
2761 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2762 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2763 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2764 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2766 <p>Limit (in bytes) on maximum size of an XML-based request
2767 body. A value of <code>0</code> will disable any checking.</p>
2771 <pre class="prettyprint lang-config">LimitXMLRequestBody 0</pre>
2776 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2777 <div class="directive-section"><h2><a name="Location" id="Location"><Location></a> <a name="location" id="location">Directive</a></h2>
2778 <table class="directive">
2779 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to matching
2781 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Location
2782 <var>URL-path</var>|<var>URL</var>> ... </Location></code></td></tr>
2783 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2784 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2785 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2787 <p>The <code class="directive"><Location></code> directive
2788 limits the scope of the enclosed directives by URL. It is similar to the
2789 <code class="directive"><a href="#directory"><Directory></a></code>
2790 directive, and starts a subsection which is terminated with a
2791 <code></Location></code> directive. <code class="directive"><Location></code> sections are processed in the
2792 order they appear in the configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
2793 <code>.htaccess</code> files are read, and after the <code class="directive"><a href="#files"><Files></a></code> sections.</p>
2795 <p><code class="directive"><Location></code> sections operate
2796 completely outside the filesystem. This has several consequences.
2797 Most importantly, <code class="directive"><Location></code>
2798 directives should not be used to control access to filesystem
2799 locations. Since several different URLs may map to the same
2800 filesystem location, such access controls may by circumvented.</p>
2802 <p>The enclosed directives will be applied to the request if the path component
2803 of the URL meets <em>any</em> of the following criteria:
2806 <li>The specified location matches exactly the path component of the URL.
2808 <li>The specified location, which ends in a forward slash, is a prefix
2809 of the path component of the URL (treated as a context root).
2811 <li>The specified location, with the addition of a trailing slash, is a
2812 prefix of the path component of the URL (also treated as a context root).
2816 In the example below, where no trailing slash is used, requests to
2817 /private1, /private1/ and /private1/file.txt will have the enclosed
2818 directives applied, but /private1other would not.
2820 <pre class="prettyprint lang-config"><Location "/private1">
2822 </Location></pre>
2825 In the example below, where a trailing slash is used, requests to
2826 /private2/ and /private2/file.txt will have the enclosed
2827 directives applied, but /private2 and /private2other would not.
2829 <pre class="prettyprint lang-config"><Location "/private2<em>/</em>">
2831 </Location></pre>
2834 <div class="note"><h3>When to use <code class="directive"><Location></code></h3>
2836 <p>Use <code class="directive"><Location></code> to apply
2837 directives to content that lives outside the filesystem. For
2838 content that lives in the filesystem, use <code class="directive"><a href="#directory"><Directory></a></code> and <code class="directive"><a href="#files"><Files></a></code>. An exception is
2839 <code><Location "/"></code>, which is an easy way to
2840 apply a configuration to the entire server.</p>
2843 <p>For all origin (non-proxy) requests, the URL to be matched is a
2844 URL-path of the form <code>/path/</code>. <em>No scheme, hostname,
2845 port, or query string may be included.</em> For proxy requests, the
2846 URL to be matched is of the form
2847 <code>scheme://servername/path</code>, and you must include the
2850 <p>The URL may use wildcards. In a wild-card string, <code>?</code> matches
2851 any single character, and <code>*</code> matches any sequences of
2852 characters. Neither wildcard character matches a / in the URL-path.</p>
2854 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
2855 can also be used, with the addition of the <code>~</code>
2856 character. For example:</p>
2858 <pre class="prettyprint lang-config"><Location ~ "/(extra|special)/data">
2860 </Location></pre>
2863 <p>would match URLs that contained the substring <code>/extra/data</code>
2864 or <code>/special/data</code>. The directive <code class="directive"><a href="#locationmatch"><LocationMatch></a></code> behaves
2865 identical to the regex version of <code class="directive"><Location></code>, and is preferred, for the
2866 simple reason that <code>~</code> is hard to distinguish from
2867 <code>-</code> in many fonts.</p>
2869 <p>The <code class="directive"><Location></code>
2870 functionality is especially useful when combined with the
2871 <code class="directive"><a href="#sethandler">SetHandler</a></code>
2872 directive. For example, to enable status requests but allow them
2873 only from browsers at <code>example.com</code>, you might use:</p>
2875 <pre class="prettyprint lang-config"><Location "/status">
2876 SetHandler server-status
2877 Require host example.com
2878 </Location></pre>
2881 <div class="note"><h3>Note about / (slash)</h3>
2882 <p>The slash character has special meaning depending on where in a
2883 URL it appears. People may be used to its behavior in the filesystem
2884 where multiple adjacent slashes are frequently collapsed to a single
2885 slash (<em>i.e.</em>, <code>/home///foo</code> is the same as
2886 <code>/home/foo</code>). In URL-space this is not necessarily true.
2887 The <code class="directive"><a href="#locationmatch"><LocationMatch></a></code>
2888 directive and the regex version of <code class="directive"><Location></code> require you to explicitly specify multiple
2889 slashes if that is your intention.</p>
2891 <p>For example, <code><LocationMatch "^/abc"></code> would match
2892 the request URL <code>/abc</code> but not the request URL <code>
2893 //abc</code>. The (non-regex) <code class="directive"><Location></code> directive behaves similarly when used for
2894 proxy requests. But when (non-regex) <code class="directive"><Location></code> is used for non-proxy requests it will
2895 implicitly match multiple slashes with a single slash. For example,
2896 if you specify <code><Location "/abc/def"></code> and the
2897 request is to <code>/abc//def</code> then it will match.</p>
2902 <li><a href="../sections.html">How <Directory>, <Location>
2903 and <Files> sections work</a> for an explanation of how these
2904 different sections are combined when a request is received.</li>
2905 <li><code class="directive"><a href="#locationmatch">LocationMatch</a></code></li>
2908 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2909 <div class="directive-section"><h2><a name="LocationMatch" id="LocationMatch"><LocationMatch></a> <a name="locationmatch" id="locationmatch">Directive</a></h2>
2910 <table class="directive">
2911 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to regular-expression
2912 matching URLs</td></tr>
2913 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LocationMatch
2914 <var>regex</var>> ... </LocationMatch></code></td></tr>
2915 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2916 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2917 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2919 <p>The <code class="directive"><LocationMatch></code> directive
2920 limits the scope of the enclosed directives by URL, in an identical manner
2921 to <code class="directive"><a href="#location"><Location></a></code>. However,
2922 it takes a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>
2923 as an argument instead of a simple string. For example:</p>
2925 <pre class="prettyprint lang-config"><LocationMatch "/(extra|special)/data">
2927 </LocationMatch></pre>
2930 <p>would match URLs that contained the substring <code>/extra/data</code>
2931 or <code>/special/data</code>.</p>
2933 <div class="note"><p>If the intent is that a URL <strong>starts with</strong>
2934 <code>/extra/data</code>, rather than merely
2935 <strong>contains</strong> <code>/extra/data</code>, prefix the
2936 regular expression with a <code>^</code> to require this.</p>
2938 <pre class="prettyprint lang-config"><LocationMatch "^/(extra|special)/data"></pre>
2942 <p>From 2.4.8 onwards, named groups and backreferences are captured and
2943 written to the environment with the corresponding name prefixed with
2944 "MATCH_" and in upper case. This allows elements of URLs to be referenced
2945 from within <a href="../expr.html">expressions</a> and modules like
2946 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
2947 (unnamed) backreferences are ignored. Use named groups instead.</p>
2949 <pre class="prettyprint lang-config"><LocationMatch "^/combined/(?<sitename>[^/]+)">
2950 require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
2951 </LocationMatch></pre>
2956 <li><a href="../sections.html">How <Directory>, <Location>
2957 and <Files> sections work</a> for an explanation of how these
2958 different sections are combined when a request is received</li>
2961 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2962 <div class="directive-section"><h2><a name="LogLevel" id="LogLevel">LogLevel</a> <a name="loglevel" id="loglevel">Directive</a></h2>
2963 <table class="directive">
2964 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls the verbosity of the ErrorLog</td></tr>
2965 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel [<var>module</var>:]<var>level</var>
2966 [<var>module</var>:<var>level</var>] ...
2968 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LogLevel warn</code></td></tr>
2969 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2970 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2971 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2972 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Per-module and per-directory configuration is available in
2973 Apache HTTP Server 2.3.6 and later</td></tr>
2975 <p><code class="directive">LogLevel</code> adjusts the verbosity of the
2976 messages recorded in the error logs (see <code class="directive"><a href="#errorlog">ErrorLog</a></code> directive). The following
2977 <var>level</var>s are available, in order of decreasing
2980 <table class="bordered">
2983 <th><strong>Level</strong> </th>
2985 <th><strong>Description</strong> </th>
2987 <th><strong>Example</strong> </th>
2991 <td><code>emerg</code> </td>
2993 <td>Emergencies - system is unusable.</td>
2995 <td>"Child cannot open lock file. Exiting"</td>
2999 <td><code>alert</code> </td>
3001 <td>Action must be taken immediately.</td>
3003 <td>"getpwuid: couldn't determine user name from uid"</td>
3007 <td><code>crit</code> </td>
3009 <td>Critical Conditions.</td>
3011 <td>"socket: Failed to get a socket, exiting child"</td>
3015 <td><code>error</code> </td>
3017 <td>Error conditions.</td>
3019 <td>"Premature end of script headers"</td>
3023 <td><code>warn</code> </td>
3025 <td>Warning conditions.</td>
3027 <td>"child process 1234 did not exit, sending another
3032 <td><code>notice</code> </td>
3034 <td>Normal but significant condition.</td>
3036 <td>"httpd: caught SIGBUS, attempting to dump core in
3041 <td><code>info</code> </td>
3043 <td>Informational.</td>
3045 <td>"Server seems busy, (you may need to increase
3046 StartServers, or Min/MaxSpareServers)..."</td>
3050 <td><code>debug</code> </td>
3052 <td>Debug-level messages</td>
3054 <td>"Opening config file ..."</td>
3057 <td><code>trace1</code> </td>
3059 <td>Trace messages</td>
3061 <td>"proxy: FTP: control connection complete"</td>
3064 <td><code>trace2</code> </td>
3066 <td>Trace messages</td>
3068 <td>"proxy: CONNECT: sending the CONNECT request to the remote proxy"</td>
3071 <td><code>trace3</code> </td>
3073 <td>Trace messages</td>
3075 <td>"openssl: Handshake: start"</td>
3078 <td><code>trace4</code> </td>
3080 <td>Trace messages</td>
3082 <td>"read from buffered SSL brigade, mode 0, 17 bytes"</td>
3085 <td><code>trace5</code> </td>
3087 <td>Trace messages</td>
3089 <td>"map lookup FAILED: map=rewritemap key=keyname"</td>
3092 <td><code>trace6</code> </td>
3094 <td>Trace messages</td>
3096 <td>"cache lookup FAILED, forcing new map lookup"</td>
3099 <td><code>trace7</code> </td>
3101 <td>Trace messages, dumping large amounts of data</td>
3103 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3106 <td><code>trace8</code> </td>
3108 <td>Trace messages, dumping large amounts of data</td>
3110 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3114 <p>When a particular level is specified, messages from all
3115 other levels of higher significance will be reported as well.
3116 <em>E.g.</em>, when <code>LogLevel info</code> is specified,
3117 then messages with log levels of <code>notice</code> and
3118 <code>warn</code> will also be posted.</p>
3120 <p>Using a level of at least <code>crit</code> is
3125 <pre class="prettyprint lang-config">LogLevel notice</pre>
3128 <div class="note"><h3>Note</h3>
3129 <p>When logging to a regular file, messages of the level
3130 <code>notice</code> cannot be suppressed and thus are always
3131 logged. However, this doesn't apply when logging is done
3132 using <code>syslog</code>.</p>
3135 <p>Specifying a level without a module name will reset the level
3136 for all modules to that level. Specifying a level with a module
3137 name will set the level for that module only. It is possible to
3138 use the module source file name, the module identifier, or the
3139 module identifier with the trailing <code>_module</code> omitted
3140 as module specification. This means the following three specifications
3143 <pre class="prettyprint lang-config">LogLevel info ssl:warn
3144 LogLevel info mod_ssl.c:warn
3145 LogLevel info ssl_module:warn</pre>
3148 <p>It is also possible to change the level per directory:</p>
3150 <pre class="prettyprint lang-config">LogLevel info
3151 <Directory "/usr/local/apache/htdocs/app">
3153 </Directory></pre>
3157 Per directory loglevel configuration only affects messages that are
3158 logged after the request has been parsed and that are associated with
3159 the request. Log messages which are associated with the server or
3160 the connection are not affected. The latter can be influenced by the
3161 <code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code> directive,
3167 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
3168 <li><code class="directive"><a href="#errorlogformat">ErrorLogFormat</a></code></li>
3169 <li><code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code></li>
3170 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
3173 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3174 <div class="directive-section"><h2><a name="LogLevelOverride" id="LogLevelOverride">LogLevelOverride</a> <a name="logleveloverride" id="logleveloverride">Directive</a></h2>
3175 <table class="directive">
3176 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Override the verbosity of the ErrorLog for certain clients</td></tr>
3177 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel <var>ipaddress</var>[/<var>prefixlen</var>]
3178 [<var>module</var>:]<var>level</var> [<var>module</var>:<var>level</var>] ...
3180 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>unset</code></td></tr>
3181 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3182 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3183 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3184 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.5.0 and later</td></tr>
3186 <p><code class="directive">LogLevelOverride</code> adjusts the
3187 <code class="directive"><a href="#loglevel">LogLevel</a></code> for requests coming from
3188 certain client IP addresses.
3189 This allows to enable verbose logging only for certain test clients.
3190 The IP address is checked at a very early state in the connection
3191 processing. Therefore, <code class="directive">LogLevelOverride</code> allows to
3192 change the log level for things like the SSL handshake which happen before
3193 a <code class="directive"><a href="#loglevel">LogLevel</a></code> directive in an
3194 <code class="directive"><a href="#if"><If></a></code> container would
3197 <p><code class="directive">LogLevelOverride</code> accepts either a single
3198 IP-address or a CIDR IP-address/len subnet specification.
3199 For the syntax of the loglevel specification, see the
3200 <code class="directive"><a href="#loglevel">LogLevel</a></code> directive.</p>
3202 <p>For requests that match a <code class="directive">LogLevelOverride</code>
3203 directive, per-directory specifications of
3204 <code class="directive"><a href="#loglevel">LogLevel</a></code> are ignored.</p>
3208 <pre class="prettyprint lang-config"> LogLevelOverride 192.0.2.0/24 ssl:trace6
3209 LogLevelOverride 192.0.2.7 ssl:trace8</pre>
3213 <code class="directive">LogLevelOverride</code> only affects
3214 log messages that are associated with the request or the connection.
3215 Log messages which are associated with the server are not affected.
3221 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
3224 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3225 <div class="directive-section"><h2><a name="MaxKeepAliveRequests" id="MaxKeepAliveRequests">MaxKeepAliveRequests</a> <a name="maxkeepaliverequests" id="maxkeepaliverequests">Directive</a></h2>
3226 <table class="directive">
3227 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of requests allowed on a persistent
3228 connection</td></tr>
3229 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxKeepAliveRequests <var>number</var></code></td></tr>
3230 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxKeepAliveRequests 100</code></td></tr>
3231 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3232 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3233 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3235 <p>The <code class="directive">MaxKeepAliveRequests</code> directive
3236 limits the number of requests allowed per connection when
3237 <code class="directive"><a href="#keepalive">KeepAlive</a></code> is on. If it is
3238 set to <code>0</code>, unlimited requests will be allowed. We
3239 recommend that this setting be kept to a high value for maximum
3240 server performance.</p>
3244 <pre class="prettyprint lang-config">MaxKeepAliveRequests 500</pre>
3248 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3249 <div class="directive-section"><h2><a name="MaxRangeOverlaps" id="MaxRangeOverlaps">MaxRangeOverlaps</a> <a name="maxrangeoverlaps" id="maxrangeoverlaps">Directive</a></h2>
3250 <table class="directive">
3251 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of overlapping ranges (eg: <code>100-200,150-300</code>) allowed before returning the complete
3253 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxRangeOverlaps default | unlimited | none | <var>number-of-ranges</var></code></td></tr>
3254 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeOverlaps 20</code></td></tr>
3255 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3256 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3257 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3258 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3260 <p>The <code class="directive">MaxRangeOverlaps</code> directive
3261 limits the number of overlapping HTTP ranges the server is willing to
3262 return to the client. If more overlapping ranges than permitted are requested,
3263 the complete resource is returned instead.</p>
3266 <dt><strong>default</strong></dt>
3267 <dd>Limits the number of overlapping ranges to a compile-time default of 20.</dd>
3269 <dt><strong>none</strong></dt>
3270 <dd>No overlapping Range headers are allowed.</dd>
3272 <dt><strong>unlimited</strong></dt>
3273 <dd>The server does not limit the number of overlapping ranges it is
3274 willing to satisfy.</dd>
3276 <dt><var>number-of-ranges</var></dt>
3277 <dd>A positive number representing the maximum number of overlapping ranges the
3278 server is willing to satisfy.</dd>
3282 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3283 <div class="directive-section"><h2><a name="MaxRangeReversals" id="MaxRangeReversals">MaxRangeReversals</a> <a name="maxrangereversals" id="maxrangereversals">Directive</a></h2>
3284 <table class="directive">
3285 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of range reversals (eg: <code>100-200,50-70</code>) allowed before returning the complete
3287 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxRangeReversals default | unlimited | none | <var>number-of-ranges</var></code></td></tr>
3288 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeReversals 20</code></td></tr>
3289 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3290 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3291 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3292 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3294 <p>The <code class="directive">MaxRangeReversals</code> directive
3295 limits the number of HTTP Range reversals the server is willing to
3296 return to the client. If more ranges reversals than permitted are requested,
3297 the complete resource is returned instead.</p>
3300 <dt><strong>default</strong></dt>
3301 <dd>Limits the number of range reversals to a compile-time default of 20.</dd>
3303 <dt><strong>none</strong></dt>
3304 <dd>No Range reversals headers are allowed.</dd>
3306 <dt><strong>unlimited</strong></dt>
3307 <dd>The server does not limit the number of range reversals it is
3308 willing to satisfy.</dd>
3310 <dt><var>number-of-ranges</var></dt>
3311 <dd>A positive number representing the maximum number of range reversals the
3312 server is willing to satisfy.</dd>
3316 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3317 <div class="directive-section"><h2><a name="MaxRanges" id="MaxRanges">MaxRanges</a> <a name="maxranges" id="maxranges">Directive</a></h2>
3318 <table class="directive">
3319 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of ranges allowed before returning the complete
3321 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxRanges default | unlimited | none | <var>number-of-ranges</var></code></td></tr>
3322 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRanges 200</code></td></tr>
3323 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3324 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3325 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3326 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3328 <p>The <code class="directive">MaxRanges</code> directive
3329 limits the number of HTTP ranges the server is willing to
3330 return to the client. If more ranges than permitted are requested,
3331 the complete resource is returned instead.</p>
3334 <dt><strong>default</strong></dt>
3335 <dd>Limits the number of ranges to a compile-time default of 200.</dd>
3337 <dt><strong>none</strong></dt>
3338 <dd>Range headers are ignored.</dd>
3340 <dt><strong>unlimited</strong></dt>
3341 <dd>The server does not limit the number of ranges it is
3342 willing to satisfy.</dd>
3344 <dt><var>number-of-ranges</var></dt>
3345 <dd>A positive number representing the maximum number of ranges the
3346 server is willing to satisfy.</dd>
3350 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3351 <div class="directive-section"><h2><a name="MergeTrailers" id="MergeTrailers">MergeTrailers</a> <a name="mergetrailers" id="mergetrailers">Directive</a></h2>
3352 <table class="directive">
3353 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether trailers are merged into headers</td></tr>
3354 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MergeTrailers [on|off]</code></td></tr>
3355 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MergeTrailers off</code></td></tr>
3356 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3357 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3358 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3359 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.4.11 and later</td></tr>
3361 <p>This directive controls whether HTTP trailers are copied into the
3362 internal representation of HTTP headers. This merging occurs when the
3363 request body has been completely consumed, long after most header
3364 processing would have a chance to examine or modify request headers.</p>
3365 <p>This option is provided for compatibility with releases prior to 2.4.11,
3366 where trailers were always merged.</p>
3369 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3370 <div class="directive-section"><h2><a name="Mutex" id="Mutex">Mutex</a> <a name="mutex" id="mutex">Directive</a></h2>
3371 <table class="directive">
3372 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures mutex mechanism and lock file directory for all
3373 or specified mutexes</td></tr>
3374 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Mutex <var>mechanism</var> [default|<var>mutex-name</var>] ... [OmitPID]</code></td></tr>
3375 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Mutex default</code></td></tr>
3376 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3377 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3378 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3379 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.4 and later</td></tr>
3381 <p>The <code class="directive">Mutex</code> directive sets the mechanism,
3382 and optionally the lock file location, that httpd and modules use
3383 to serialize access to resources. Specify <code>default</code> as
3384 the second argument to change the settings for all mutexes; specify
3385 a mutex name (see table below) as the second argument to override
3386 defaults only for that mutex.</p>
3388 <p>The <code class="directive">Mutex</code> directive is typically used in
3389 the following exceptional situations:</p>
3392 <li>change the mutex mechanism when the default mechanism selected
3393 by <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> has a functional or performance
3396 <li>change the directory used by file-based mutexes when the
3397 default directory does not support locking</li>
3400 <div class="note"><h3>Supported modules</h3>
3401 <p>This directive only configures mutexes which have been registered
3402 with the core server using the <code>ap_mutex_register()</code> API.
3403 All modules bundled with httpd support the <code class="directive">Mutex</code>
3404 directive, but third-party modules may not. Consult the documentation
3405 of the third-party module, which must indicate the mutex name(s) which
3406 can be configured if this directive is supported.</p>
3409 <p>The following mutex <em>mechanisms</em> are available:</p>
3411 <li><code>default | yes</code>
3412 <p>This selects the default locking implementation, as determined by
3413 <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a>. The default locking implementation can
3414 be displayed by running <code class="program"><a href="../programs/httpd.html">httpd</a></code> with the
3415 <code>-V</code> option.</p></li>
3417 <li><code>none | no</code>
3418 <p>This effectively disables the mutex, and is only allowed for a
3419 mutex if the module indicates that it is a valid choice. Consult the
3420 module documentation for more information.</p></li>
3422 <li><code>posixsem</code>
3423 <p>This is a mutex variant based on a Posix semaphore.</p>
3425 <div class="warning"><h3>Warning</h3>
3426 <p>The semaphore ownership is not recovered if a thread in the process
3427 holding the mutex segfaults, resulting in a hang of the web server.</p>
3431 <li><code>sysvsem</code>
3432 <p>This is a mutex variant based on a SystemV IPC semaphore.</p>
3434 <div class="warning"><h3>Warning</h3>
3435 <p>It is possible to "leak" SysV semaphores if processes crash
3436 before the semaphore is removed.</p>
3439 <div class="warning"><h3>Security</h3>
3440 <p>The semaphore API allows for a denial of service attack by any
3441 CGIs running under the same uid as the webserver (<em>i.e.</em>,
3442 all CGIs, unless you use something like <code class="program"><a href="../programs/suexec.html">suexec</a></code>
3443 or <code>cgiwrapper</code>).</p>
3447 <li><code>sem</code>
3448 <p>This selects the "best" available semaphore implementation, choosing
3449 between Posix and SystemV IPC semaphores, in that order.</p></li>
3451 <li><code>pthread</code>
3452 <p>This is a mutex variant based on cross-process Posix thread
3455 <div class="warning"><h3>Warning</h3>
3456 <p>On most systems, if a child process terminates abnormally while
3457 holding a mutex that uses this implementation, the server will deadlock
3458 and stop responding to requests. When this occurs, the server will
3459 require a manual restart to recover.</p>
3460 <p>Solaris and Linux are notable exceptions as they provide a mechanism which
3461 usually allows the mutex to be recovered after a child process
3462 terminates abnormally while holding a mutex.</p>
3463 <p>If your system is POSIX compliant or if it implements the
3464 <code>pthread_mutexattr_setrobust_np()</code> function, you may be able
3465 to use the <code>pthread</code> option safely.</p>
3469 <li><code>fcntl:/path/to/mutex</code>
3470 <p>This is a mutex variant where a physical (lock-)file and the
3471 <code>fcntl()</code> function are used as the mutex.</p>
3473 <div class="warning"><h3>Warning</h3>
3474 <p>When multiple mutexes based on this mechanism are used within
3475 multi-threaded, multi-process environments, deadlock errors (EDEADLK)
3476 can be reported for valid mutex operations if <code>fcntl()</code>
3477 is not thread-aware, such as on Solaris.</p>
3481 <li><code>flock:/path/to/mutex</code>
3482 <p>This is similar to the <code>fcntl:/path/to/mutex</code> method
3483 with the exception that the <code>flock()</code> function is used to
3484 provide file locking.</p></li>
3486 <li><code>file:/path/to/mutex</code>
3487 <p>This selects the "best" available file locking implementation,
3488 choosing between <code>fcntl</code> and <code>flock</code>, in that
3492 <p>Most mechanisms are only available on selected platforms, where the
3493 underlying platform and <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> support it. Mechanisms
3494 which aren't available on all platforms are <em>posixsem</em>,
3495 <em>sysvsem</em>, <em>sem</em>, <em>pthread</em>, <em>fcntl</em>,
3496 <em>flock</em>, and <em>file</em>.</p>
3498 <p>With the file-based mechanisms <em>fcntl</em> and <em>flock</em>,
3499 the path, if provided, is a directory where the lock file will be created.
3500 The default directory is httpd's run-time file directory,
3501 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. If a relative
3502 path is provided, it is relative to
3503 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. Always use a local
3504 disk filesystem for <code>/path/to/mutex</code> and never a directory residing
3505 on a NFS- or AFS-filesystem. The basename of the file will be the mutex
3506 type, an optional instance string provided by the module, and unless the
3507 <code>OmitPID</code> keyword is specified, the process id of the httpd
3508 parent process will be appended to make the file name unique, avoiding
3509 conflicts when multiple httpd instances share a lock file directory. For
3510 example, if the mutex name is <code>mpm-accept</code> and the lock file
3511 directory is <code>/var/httpd/locks</code>, the lock file name for the
3512 httpd instance with parent process id 12345 would be
3513 <code>/var/httpd/locks/mpm-accept.12345</code>.</p>
3515 <div class="warning"><h3>Security</h3>
3516 <p>It is best to <em>avoid</em> putting mutex files in a world-writable
3517 directory such as <code>/var/tmp</code> because someone could create
3518 a denial of service attack and prevent the server from starting by
3519 creating a lockfile with the same name as the one the server will try
3523 <p>The following table documents the names of mutexes used by httpd
3524 and bundled modules.</p>
3526 <table class="bordered"><tr class="header">
3529 <th>Protected resource</th>
3532 <td><code>mpm-accept</code></td>
3533 <td><code class="module"><a href="../mod/prefork.html">prefork</a></code> and <code class="module"><a href="../mod/worker.html">worker</a></code> MPMs</td>
3534 <td>incoming connections, to avoid the thundering herd problem;
3535 for more information, refer to the
3536 <a href="../misc/perf-tuning.html">performance tuning</a>
3540 <td><code>authdigest-client</code></td>
3541 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3542 <td>client list in shared memory</td>
3545 <td><code>authdigest-opaque</code></td>
3546 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3547 <td>counter in shared memory</td>
3550 <td><code>ldap-cache</code></td>
3551 <td><code class="module"><a href="../mod/mod_ldap.html">mod_ldap</a></code></td>
3552 <td>LDAP result cache</td>
3555 <td><code>rewrite-map</code></td>
3556 <td><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></td>
3557 <td>communication with external mapping programs, to avoid
3558 intermixed I/O from multiple requests</td>
3561 <td><code>ssl-cache</code></td>
3562 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3563 <td>SSL session cache</td>
3566 <td><code>ssl-stapling</code></td>
3567 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3568 <td>OCSP stapling response cache</td>
3571 <td><code>watchdog-callback</code></td>
3572 <td><code class="module"><a href="../mod/mod_watchdog.html">mod_watchdog</a></code></td>
3573 <td>callback function of a particular client module</td>
3577 <p>The <code>OmitPID</code> keyword suppresses the addition of the httpd
3578 parent process id from the lock file name.</p>
3580 <p>In the following example, the mutex mechanism for the MPM accept
3581 mutex will be changed from the compiled-in default to <code>fcntl</code>,
3582 with the associated lock file created in directory
3583 <code>/var/httpd/locks</code>. The mutex mechanism for all other mutexes
3584 will be changed from the compiled-in default to <code>sysvsem</code>.</p>
3586 <pre class="prettyprint lang-config">Mutex sysvsem default
3587 Mutex fcntl:/var/httpd/locks mpm-accept</pre>
3591 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3592 <div class="directive-section"><h2><a name="NameVirtualHost" id="NameVirtualHost">NameVirtualHost</a> <a name="namevirtualhost" id="namevirtualhost">Directive</a></h2>
3593 <table class="directive">
3594 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>DEPRECATED: Designates an IP address for name-virtual
3596 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NameVirtualHost <var>addr</var>[:<var>port</var>]</code></td></tr>
3597 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3598 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3599 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3602 <p>Prior to 2.3.11, <code class="directive">NameVirtualHost</code> was required
3603 to instruct the server that a particular IP address and port combination
3604 was usable as a name-based virtual host. In 2.3.11 and later,
3605 any time an IP address and port combination is used in multiple virtual
3606 hosts, name-based virtual hosting is automatically enabled for that address.</p>
3608 <p>This directive currently has no effect.</p>
3612 <li><a href="../vhosts/">Virtual Hosts
3613 documentation</a></li>
3616 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3617 <div class="directive-section"><h2><a name="Options" id="Options">Options</a> <a name="options" id="options">Directive</a></h2>
3618 <table class="directive">
3619 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures what features are available in a particular
3621 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Options
3622 [+|-]<var>option</var> [[+|-]<var>option</var>] ...</code></td></tr>
3623 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Options FollowSymlinks</code></td></tr>
3624 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3625 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
3626 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3627 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3628 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The default was changed from All to FollowSymlinks in 2.3.11</td></tr>
3630 <p>The <code class="directive">Options</code> directive controls which
3631 server features are available in a particular directory.</p>
3633 <p><var>option</var> can be set to <code>None</code>, in which
3634 case none of the extra features are enabled, or one or more of
3638 <dt><code>All</code></dt>
3640 <dd>All options except for <code>MultiViews</code>.</dd>
3642 <dt><code>ExecCGI</code></dt>
3645 Execution of CGI scripts using <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>
3648 <dt><code>FollowSymLinks</code></dt>
3651 The server will follow symbolic links in this directory. This is
3652 the default setting.
3654 <p>Even though the server follows the symlink it does <em>not</em>
3655 change the pathname used to match against <code class="directive"><a href="#directory"><Directory></a></code> sections.</p>
3657 <p>The <code>FollowSymLinks</code> and
3658 <code>SymLinksIfOwnerMatch</code> <code class="directive"><a href="#options">Options</a></code> work only in <code class="directive"><a href="#directory"><Directory></a></code> sections or
3659 <code>.htaccess</code> files.</p>
3661 <p>Omitting this option should not be considered a security restriction,
3662 since symlink testing is subject to race conditions that make it
3666 <dt><code>Includes</code></dt>
3669 Server-side includes provided by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
3672 <dt><code>IncludesNOEXEC</code></dt>
3676 Server-side includes are permitted, but the <code>#exec
3677 cmd</code> and <code>#exec cgi</code> are disabled. It is still
3678 possible to <code>#include virtual</code> CGI scripts from
3679 <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>ed
3682 <dt><code>Indexes</code></dt>
3685 If a URL which maps to a directory is requested and there
3686 is no <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
3687 (<em>e.g.</em>, <code>index.html</code>) in that directory, then
3688 <code class="module"><a href="../mod/mod_autoindex.html">mod_autoindex</a></code> will return a formatted listing
3689 of the directory.</dd>
3691 <dt><code>MultiViews</code></dt>
3694 <a href="../content-negotiation.html">Content negotiated</a>
3695 "MultiViews" are allowed using
3696 <code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code>.
3697 <div class="note"><h3>Note</h3> <p>This option gets ignored if set
3698 anywhere other than <code class="directive"><a href="#directory"><Directory></a></code>, as <code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code>
3699 needs real resources to compare against and evaluate from.</p></div>
3702 <dt><code>SymLinksIfOwnerMatch</code></dt>
3704 <dd>The server will only follow symbolic links for which the
3705 target file or directory is owned by the same user id as the
3708 <div class="note"><h3>Note</h3>
3709 <p>The <code>FollowSymLinks</code> and
3710 <code>SymLinksIfOwnerMatch</code> <code class="directive"><a href="#options">Options</a></code> work only in <code class="directive"><a href="#directory"><Directory></a></code> sections or
3711 <code>.htaccess</code> files.</p>
3713 <p>This option should not be considered a security restriction,
3714 since symlink testing is subject to race conditions that make it
3719 <p>Normally, if multiple <code class="directive">Options</code> could
3720 apply to a directory, then the most specific one is used and
3721 others are ignored; the options are not merged. (See <a href="../sections.html#merging">how sections are merged</a>.)
3722 However if <em>all</em> the options on the
3723 <code class="directive">Options</code> directive are preceded by a
3724 <code>+</code> or <code>-</code> symbol, the options are
3725 merged. Any options preceded by a <code>+</code> are added to the
3726 options currently in force, and any options preceded by a
3727 <code>-</code> are removed from the options currently in
3730 <div class="note"><h3>Note</h3>
3731 <p>Mixing <code class="directive">Options</code> with a <code>+</code> or
3732 <code>-</code> with those without is not valid syntax and will be
3733 rejected during server startup by the syntax check with an abort.</p>
3736 <p>For example, without any <code>+</code> and <code>-</code> symbols:</p>
3738 <pre class="prettyprint lang-config"><Directory "/web/docs">
3739 Options Indexes FollowSymLinks
3742 <Directory "/web/docs/spec">
3744 </Directory></pre>
3747 <p>then only <code>Includes</code> will be set for the
3748 <code>/web/docs/spec</code> directory. However if the second
3749 <code class="directive">Options</code> directive uses the <code>+</code> and
3750 <code>-</code> symbols:</p>
3752 <pre class="prettyprint lang-config"><Directory "/web/docs">
3753 Options Indexes FollowSymLinks
3756 <Directory "/web/docs/spec">
3757 Options +Includes -Indexes
3758 </Directory></pre>
3761 <p>then the options <code>FollowSymLinks</code> and
3762 <code>Includes</code> are set for the <code>/web/docs/spec</code>
3765 <div class="note"><h3>Note</h3>
3766 <p>Using <code>-IncludesNOEXEC</code> or
3767 <code>-Includes</code> disables server-side includes completely
3768 regardless of the previous setting.</p>
3771 <p>The default in the absence of any other settings is
3772 <code>FollowSymlinks</code>.</p>
3775 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3776 <div class="directive-section"><h2><a name="Protocol" id="Protocol">Protocol</a> <a name="protocol" id="protocol">Directive</a></h2>
3777 <table class="directive">
3778 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocol for a listening socket</td></tr>
3779 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocol <var>protocol</var></code></td></tr>
3780 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3781 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3782 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3783 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>On Windows, only available from Apache 2.3.3 and later.</td></tr>
3785 <p>This directive specifies the protocol used for a specific listening socket.
3786 The protocol is used to determine which module should handle a request and
3787 to apply protocol specific optimizations with the <code class="directive">AcceptFilter</code>
3790 <p>You only need to set the protocol if you are running on non-standard ports;
3791 otherwise, <code>http</code> is assumed for port 80 and <code>https</code>
3794 <p>For example, if you are running <code>https</code> on a non-standard port,
3795 specify the protocol explicitly:</p>
3797 <pre class="prettyprint lang-config">Protocol https</pre>
3800 <p>You can also specify the protocol using the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code> directive.</p>
3804 <li><code class="directive"><a href="#acceptfilter">AcceptFilter</a></code></li>
3805 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
3808 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3809 <div class="directive-section"><h2><a name="Protocols" id="Protocols">Protocols</a> <a name="protocols" id="protocols">Directive</a></h2>
3810 <table class="directive">
3811 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocols available for a server/virtual host</td></tr>
3812 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocols <var>protocol</var> ...</code></td></tr>
3813 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Protocols http/1.1</code></td></tr>
3814 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3815 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3816 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3817 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3819 <p>This directive specifies the list of protocols supported for a
3820 server/virtual host. The list determines the allowed protocols
3821 a client may negotiate for this server/host.</p>
3823 <p>You need to set protocols if you want to extend the available
3824 protocols for a server/host. By default, only the http/1.1 protocol
3825 (which includes the compatibility with 1.0 and 0.9 clients) is
3828 <p>For example, if you want to support HTTP/2 for a server with TLS,
3831 <pre class="prettyprint lang-config">Protocols h2 http/1.1</pre>
3834 <p>Valid protocols are <code>http/1.1</code> for http and https connections,
3835 <code>h2</code> on https connections and <code>h2c</code> for http
3836 connections. Modules may enable more protocols.</p>
3838 <p>It is safe to specify protocols that are unavailable/disabled. Such
3839 protocol names will simply be ignored.</p>
3841 <p>Protocols specified in base servers are inherited for virtual hosts
3842 only if the virtual host has no own Protocols directive. Or, the other
3843 way around, Protocols directives in virtual hosts replace any
3844 such directive in the base server.
3850 <li><code class="directive"><a href="#protocolshonororder">ProtocolsHonorOrder</a></code></li>
3853 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3854 <div class="directive-section"><h2><a name="ProtocolsHonorOrder" id="ProtocolsHonorOrder">ProtocolsHonorOrder</a> <a name="protocolshonororder" id="protocolshonororder">Directive</a></h2>
3855 <table class="directive">
3856 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines if order of Protocols determines precedence during negotiation</td></tr>
3857 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProtocolsHonorOrder On|Off</code></td></tr>
3858 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProtocolsHonorOrder On</code></td></tr>
3859 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3860 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3861 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3862 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3864 <p>This directive specifies if the server should honor the order in which
3865 the <code class="directive">Protocols</code> directive lists protocols.</p>
3867 <p>If configured Off, the client supplied list order of protocols has
3868 precedence over the order in the server configuration.</p>
3870 <p>With <code class="directive">ProtocolsHonorOrder</code> set to <code>on</code>
3871 (default), the client ordering does not matter and only the ordering
3872 in the server settings influences the outcome of the protocol
3878 <li><code class="directive"><a href="#protocols">Protocols</a></code></li>
3881 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3882 <div class="directive-section"><h2><a name="QualifyRedirectURL" id="QualifyRedirectURL">QualifyRedirectURL</a> <a name="qualifyredirecturl" id="qualifyredirecturl">Directive</a></h2>
3883 <table class="directive">
3884 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls whether the REDIRECT_URL environment variable is
3885 fully qualified</td></tr>
3886 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>QualifyRedirectURL ON|OFF</code></td></tr>
3887 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>QualifyRedirectURL OFF</code></td></tr>
3888 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3889 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3890 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3891 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3892 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directive supported in 2.4.18 and later. 2.4.17 acted
3893 as if 'QualifyRedirectURL ON' was configured.</td></tr>
3895 <p>This directive controls whether the server will ensure that the
3896 REDIRECT_URL environment variable is fully qualified. By default,
3897 the variable contains the verbatim URL requested by the client,
3898 such as "/index.html". With <code class="directive"><a href="#qualifyredirecturl on">QualifyRedirectURL ON</a></code>, the same request would result in a
3899 value such as "http://www.example.com/index.html".</p>
3900 <p>Even without this directive set, when a request is issued against a
3901 fully qualified URL, REDIRECT_URL will remain fully qualified.
3905 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3906 <div class="directive-section"><h2><a name="RegisterHttpMethod" id="RegisterHttpMethod">RegisterHttpMethod</a> <a name="registerhttpmethod" id="registerhttpmethod">Directive</a></h2>
3907 <table class="directive">
3908 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Register non-standard HTTP methods</td></tr>
3909 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RegisterHttpMethod <var>method</var> [<var>method</var> [...]]</code></td></tr>
3910 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3911 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3912 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3914 <p>HTTP Methods that are not conforming to the relvant RFCs are normally
3915 rejected by request processing in Apache HTTPD. To avoid this, modules
3916 can register non-standard HTTP methods they support.
3917 The <code class="directive">RegisterHttpMethod</code> allows to register such
3918 methods manually. This can be useful if such methods are forwarded
3919 for external processing, e.g. to a CGI script.</p>
3922 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3923 <div class="directive-section"><h2><a name="RLimitCPU" id="RLimitCPU">RLimitCPU</a> <a name="rlimitcpu" id="rlimitcpu">Directive</a></h2>
3924 <table class="directive">
3925 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the CPU consumption of processes launched
3926 by Apache httpd children</td></tr>
3927 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RLimitCPU <var>seconds</var>|max [<var>seconds</var>|max]</code></td></tr>
3928 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3929 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3930 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3931 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3932 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3934 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3935 resource limit for all processes and the second parameter sets
3936 the maximum resource limit. Either parameter can be a number,
3937 or <code>max</code> to indicate to the server that the limit should
3938 be set to the maximum allowed by the operating system
3939 configuration. Raising the maximum resource limit requires that
3940 the server is running as <code>root</code> or in the initial startup
3943 <p>This applies to processes forked from Apache httpd children
3944 servicing requests, not the Apache httpd children themselves. This
3945 includes CGI scripts and SSI exec commands, but not any
3946 processes forked from the Apache httpd parent, such as piped
3949 <p>CPU resource limits are expressed in seconds per
3954 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
3955 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3958 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3959 <div class="directive-section"><h2><a name="RLimitMEM" id="RLimitMEM">RLimitMEM</a> <a name="rlimitmem" id="rlimitmem">Directive</a></h2>
3960 <table class="directive">
3961 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the memory consumption of processes launched
3962 by Apache httpd children</td></tr>
3963 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RLimitMEM <var>bytes</var>|max [<var>bytes</var>|max]</code></td></tr>
3964 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3965 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3966 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3967 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3968 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3970 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3971 resource limit for all processes and the second parameter sets
3972 the maximum resource limit. Either parameter can be a number,
3973 or <code>max</code> to indicate to the server that the limit should
3974 be set to the maximum allowed by the operating system
3975 configuration. Raising the maximum resource limit requires that
3976 the server is running as <code>root</code> or in the initial startup
3979 <p>This applies to processes forked from Apache httpd children
3980 servicing requests, not the Apache httpd children themselves. This
3981 includes CGI scripts and SSI exec commands, but not any
3982 processes forked from the Apache httpd parent, such as piped
3985 <p>Memory resource limits are expressed in bytes per
3990 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
3991 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3994 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3995 <div class="directive-section"><h2><a name="RLimitNPROC" id="RLimitNPROC">RLimitNPROC</a> <a name="rlimitnproc" id="rlimitnproc">Directive</a></h2>
3996 <table class="directive">
3997 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of processes that can be launched by
3998 processes launched by Apache httpd children</td></tr>
3999 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RLimitNPROC <var>number</var>|max [<var>number</var>|max]</code></td></tr>
4000 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
4001 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4002 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
4003 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4004 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4006 <p>Takes 1 or 2 parameters. The first parameter sets the soft
4007 resource limit for all processes, and the second parameter sets
4008 the maximum resource limit. Either parameter can be a number,
4009 or <code>max</code> to indicate to the server that the limit
4010 should be set to the maximum allowed by the operating system
4011 configuration. Raising the maximum resource limit requires that
4012 the server is running as <code>root</code> or in the initial startup
4015 <p>This applies to processes forked from Apache httpd children
4016 servicing requests, not the Apache httpd children themselves. This
4017 includes CGI scripts and SSI exec commands, but not any
4018 processes forked from the Apache httpd parent, such as piped
4021 <p>Process limits control the number of processes per user.</p>
4023 <div class="note"><h3>Note</h3>
4024 <p>If CGI processes are <strong>not</strong> running
4025 under user ids other than the web server user id, this directive
4026 will limit the number of processes that the server itself can
4027 create. Evidence of this situation will be indicated by
4028 <strong><code>cannot fork</code></strong> messages in the
4029 <code>error_log</code>.</p>
4034 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
4035 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
4038 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4039 <div class="directive-section"><h2><a name="ScriptInterpreterSource" id="ScriptInterpreterSource">ScriptInterpreterSource</a> <a name="scriptinterpretersource" id="scriptinterpretersource">Directive</a></h2>
4040 <table class="directive">
4041 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
4043 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ScriptInterpreterSource Registry|Registry-Strict|Script</code></td></tr>
4044 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ScriptInterpreterSource Script</code></td></tr>
4045 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4046 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4047 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4048 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4049 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Win32 only.</td></tr>
4051 <p>This directive is used to control how Apache httpd finds the
4052 interpreter used to run CGI scripts. The default setting is
4053 <code>Script</code>. This causes Apache httpd to use the interpreter pointed to
4054 by the shebang line (first line, starting with <code>#!</code>) in the
4055 script. On Win32 systems this line usually looks like:</p>
4057 <pre class="prettyprint lang-perl">#!C:/Perl/bin/perl.exe</pre>
4060 <p>or, if <code>perl</code> is in the <code>PATH</code>, simply:</p>
4062 <pre class="prettyprint lang-perl">#!perl</pre>
4065 <p>Setting <code>ScriptInterpreterSource Registry</code> will
4066 cause the Windows Registry tree <code>HKEY_CLASSES_ROOT</code> to be
4067 searched using the script file extension (e.g., <code>.pl</code>) as a
4068 search key. The command defined by the registry subkey
4069 <code>Shell\ExecCGI\Command</code> or, if it does not exist, by the subkey
4070 <code>Shell\Open\Command</code> is used to open the script file. If the
4071 registry keys cannot be found, Apache httpd falls back to the behavior of the
4072 <code>Script</code> option.</p>
4074 <div class="warning"><h3>Security</h3>
4075 <p>Be careful when using <code>ScriptInterpreterSource
4076 Registry</code> with <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories, because
4077 Apache httpd will try to execute <strong>every</strong> file within this
4078 directory. The <code>Registry</code> setting may cause undesired
4079 program calls on files which are typically not executed. For
4080 example, the default open command on <code>.htm</code> files on
4081 most Windows systems will execute Microsoft Internet Explorer, so
4082 any HTTP request for an <code>.htm</code> file existing within the
4083 script directory would start the browser in the background on the
4084 server. This is a good way to crash your system within a minute or
4088 <p>The option <code>Registry-Strict</code> which is new in Apache HTTP Server
4089 2.0 does the same thing as <code>Registry</code> but uses only the
4090 subkey <code>Shell\ExecCGI\Command</code>. The
4091 <code>ExecCGI</code> key is not a common one. It must be
4092 configured manually in the windows registry and hence prevents
4093 accidental program calls on your system.</p>
4096 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4097 <div class="directive-section"><h2><a name="SeeRequestTail" id="SeeRequestTail">SeeRequestTail</a> <a name="seerequesttail" id="seerequesttail">Directive</a></h2>
4098 <table class="directive">
4099 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine if mod_status displays the first 63 characters
4100 of a request or the last 63, assuming the request itself is greater than
4102 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SeeRequestTail On|Off</code></td></tr>
4103 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SeeRequestTail Off</code></td></tr>
4104 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4105 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4106 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4108 <p>mod_status with <code>ExtendedStatus On</code>
4109 displays the actual request being handled.
4110 For historical purposes, only 63 characters of the request
4111 are actually stored for display purposes. This directive
4112 controls whether the 1st 63 characters are stored (the previous
4113 behavior and the default) or if the last 63 characters are. This
4114 is only applicable, of course, if the length of the request is
4115 64 characters or greater.</p>
4117 <p>If Apache httpd is handling <code>GET /disk1/storage/apache/htdocs/images/imagestore1/food/apples.jpg HTTP/1.1</code> mod_status displays as follows:
4120 <table class="bordered">
4122 <th>Off (default)</th>
4123 <td>GET /disk1/storage/apache/htdocs/images/imagestore1/food/apples</td>
4127 <td>orage/apache/htdocs/images/imagestore1/food/apples.jpg HTTP/1.1</td>
4133 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4134 <div class="directive-section"><h2><a name="ServerAdmin" id="ServerAdmin">ServerAdmin</a> <a name="serveradmin" id="serveradmin">Directive</a></h2>
4135 <table class="directive">
4136 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Email address that the server includes in error
4137 messages sent to the client</td></tr>
4138 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAdmin <var>email-address</var>|<var>URL</var></code></td></tr>
4139 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4140 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4141 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4143 <p>The <code class="directive">ServerAdmin</code> sets the contact address
4144 that the server includes in any error messages it returns to the
4145 client. If the <code>httpd</code> doesn't recognize the supplied argument
4147 assumes, that it's an <var>email-address</var> and prepends it with
4148 <code>mailto:</code> in hyperlink targets. However, it's recommended to
4149 actually use an email address, since there are a lot of CGI scripts that
4150 make that assumption. If you want to use an URL, it should point to another
4151 server under your control. Otherwise users may not be able to contact you in
4154 <p>It may be worth setting up a dedicated address for this, e.g.</p>
4156 <pre class="prettyprint lang-config">ServerAdmin www-admin@foo.example.com</pre>
4158 <p>as users do not always mention that they are talking about the
4162 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4163 <div class="directive-section"><h2><a name="ServerAlias" id="ServerAlias">ServerAlias</a> <a name="serveralias" id="serveralias">Directive</a></h2>
4164 <table class="directive">
4165 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Alternate names for a host used when matching requests
4166 to name-virtual hosts</td></tr>
4167 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAlias <var>hostname</var> [<var>hostname</var>] ...</code></td></tr>
4168 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4169 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4170 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4172 <p>The <code class="directive">ServerAlias</code> directive sets the
4173 alternate names for a host, for use with <a href="../vhosts/name-based.html">name-based virtual hosts</a>. The
4174 <code class="directive">ServerAlias</code> may include wildcards, if appropriate.</p>
4176 <pre class="prettyprint lang-config"><VirtualHost *:80>
4177 ServerName server.example.com
4178 ServerAlias server server2.example.com server2
4179 ServerAlias *.example.com
4180 UseCanonicalName Off
4182 </VirtualHost></pre>
4185 <p>Name-based virtual hosts for the best-matching set of <code class="directive"><a href="#virtualhost"><virtualhost></a></code>s are processed
4186 in the order they appear in the configuration. The first matching <code class="directive"><a href="#servername">ServerName</a></code> or <code class="directive"><a href="#serveralias">ServerAlias</a></code> is used, with no different precedence for wildcards
4187 (nor for ServerName vs. ServerAlias). </p>
4189 <p>The complete list of names in the <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
4190 directive are treated just like a (non wildcard)
4191 <code class="directive">ServerAlias</code>.</p>
4196 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4197 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4200 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4201 <div class="directive-section"><h2><a name="ServerName" id="ServerName">ServerName</a> <a name="servername" id="servername">Directive</a></h2>
4202 <table class="directive">
4203 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Hostname and port that the server uses to identify
4205 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerName [<var>scheme</var>://]<var>domain-name</var>|<var>ip-address</var>[:<var>port</var>]</code></td></tr>
4206 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4207 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4208 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4210 <p>The <code class="directive">ServerName</code> directive sets the
4211 request scheme, hostname and port that the server uses to identify itself.
4214 <p><code class="directive">ServerName</code> is used (possibly
4215 in conjunction with <code class="directive"><a href="#serveralias">ServerAlias</a></code>) to uniquely
4216 identify a virtual host, when using <a href="../vhosts/name-based.html">name-based virtual hosts</a>.</p>
4218 <p>Additionally, this is used when
4219 creating self-referential redirection URLs when
4220 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> is set to a non-default
4223 <p>For example, if the name of the
4224 machine hosting the web server is <code>simple.example.com</code>,
4225 but the machine also has the DNS alias <code>www.example.com</code>
4226 and you wish the web server to be so identified, the following
4227 directive should be used:</p>
4229 <pre class="prettyprint lang-config">ServerName www.example.com</pre>
4232 <p>The <code class="directive">ServerName</code> directive
4233 may appear anywhere within the definition of a server. However,
4234 each appearance overrides the previous appearance (within that
4237 <p>If no <code class="directive">ServerName</code> is specified, the
4238 server attempts to deduce the client visible hostname by first asking
4239 the operating system for the system hostname, and if that fails,
4240 performing a reverse lookup on an IP address present on the system.</p>
4242 <p>If no port is specified in the
4243 <code class="directive">ServerName</code>, then the server will use the
4244 port from the incoming request. For optimal reliability and
4245 predictability, you should specify an explicit hostname and port
4246 using the <code class="directive">ServerName</code> directive.</p>
4248 <p>If you are using <a href="../vhosts/name-based.html">name-based virtual hosts</a>,
4249 the <code class="directive">ServerName</code> inside a
4250 <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
4251 section specifies what hostname must appear in the request's
4252 <code>Host:</code> header to match this virtual host.</p>
4254 <p>Sometimes, the server runs behind a device that processes SSL,
4255 such as a reverse proxy, load balancer or SSL offload
4256 appliance. When this is the case, specify the
4257 <code>https://</code> scheme and the port number to which the
4258 clients connect in the <code class="directive">ServerName</code> directive
4259 to make sure that the server generates the correct
4260 self-referential URLs.
4263 <p>See the description of the
4264 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> and
4265 <code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code> directives for
4266 settings which determine whether self-referential URLs (e.g., by the
4267 <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> module) will refer to the
4268 specified port, or to the port number given in the client's request.
4271 <div class="warning">
4272 <p>Failure to set <code class="directive">ServerName</code> to a name that
4273 your server can resolve to an IP address will result in a startup
4274 warning. <code>httpd</code> will then use whatever hostname it can
4275 determine, using the system's <code>hostname</code> command. This
4276 will almost never be the hostname you actually want.</p>
4277 <div class="example"><p><code>
4278 httpd: Could not reliably determine the server's fully qualified domain name, using rocinante.local for ServerName
4285 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4286 Apache HTTP Server</a></li>
4287 <li><a href="../vhosts/">Apache HTTP Server virtual host
4288 documentation</a></li>
4289 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4290 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4291 <li><code class="directive"><a href="#serveralias">ServerAlias</a></code></li>
4294 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4295 <div class="directive-section"><h2><a name="ServerPath" id="ServerPath">ServerPath</a> <a name="serverpath" id="serverpath">Directive</a></h2>
4296 <table class="directive">
4297 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Legacy URL pathname for a name-based virtual host that
4298 is accessed by an incompatible browser</td></tr>
4299 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerPath <var>URL-path</var></code></td></tr>
4300 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4301 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4302 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4304 <p>The <code class="directive">ServerPath</code> directive sets the legacy
4305 URL pathname for a host, for use with <a href="../vhosts/">name-based virtual hosts</a>.</p>
4309 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4312 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4313 <div class="directive-section"><h2><a name="ServerRoot" id="ServerRoot">ServerRoot</a> <a name="serverroot" id="serverroot">Directive</a></h2>
4314 <table class="directive">
4315 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server installation</td></tr>
4316 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerRoot <var>directory-path</var></code></td></tr>
4317 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerRoot /usr/local/apache</code></td></tr>
4318 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4319 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4320 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4322 <p>The <code class="directive">ServerRoot</code> directive sets the
4323 directory in which the server lives. Typically it will contain the
4324 subdirectories <code>conf/</code> and <code>logs/</code>. Relative
4325 paths in other configuration directives (such as <code class="directive"><a href="#include">Include</a></code> or <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code>, for example) are taken as
4326 relative to this directory.</p>
4328 <pre class="prettyprint lang-config">ServerRoot "/home/httpd"</pre>
4331 <p>The default location of <code class="directive">ServerRoot</code> may be
4332 modified by using the <code>--prefix</code> argument to
4333 <a href="../programs/configure.html"><code>configure</code></a>, and
4334 most third-party distributions of the server have a different
4335 default location from the one listed above.</p>
4340 <li><a href="../invoking.html">the <code>-d</code>
4341 option to <code>httpd</code></a></li>
4342 <li><a href="../misc/security_tips.html#serverroot">the
4343 security tips</a> for information on how to properly set
4344 permissions on the <code class="directive">ServerRoot</code></li>
4347 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4348 <div class="directive-section"><h2><a name="ServerSignature" id="ServerSignature">ServerSignature</a> <a name="serversignature" id="serversignature">Directive</a></h2>
4349 <table class="directive">
4350 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the footer on server-generated documents</td></tr>
4351 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerSignature On|Off|EMail</code></td></tr>
4352 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerSignature Off</code></td></tr>
4353 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4354 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
4355 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4356 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4358 <p>The <code class="directive">ServerSignature</code> directive allows the
4359 configuration of a trailing footer line under server-generated
4360 documents (error messages, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> ftp directory
4361 listings, <code class="module"><a href="../mod/mod_info.html">mod_info</a></code> output, ...). The reason why you
4362 would want to enable such a footer line is that in a chain of proxies,
4363 the user often has no possibility to tell which of the chained servers
4364 actually produced a returned error message.</p>
4366 <p>The <code>Off</code>
4367 setting, which is the default, suppresses the footer line (and is
4368 therefore compatible with the behavior of Apache-1.2 and
4369 below). The <code>On</code> setting simply adds a line with the
4370 server version number and <code class="directive"><a href="#servername">ServerName</a></code> of the serving virtual host,
4371 and the <code>EMail</code> setting additionally creates a
4372 "mailto:" reference to the <code class="directive"><a href="#serveradmin">ServerAdmin</a></code> of the referenced
4375 <p>After version 2.0.44, the details of the server version number
4376 presented are controlled by the <code class="directive"><a href="#servertokens">ServerTokens</a></code> directive.</p>
4380 <li><code class="directive"><a href="#servertokens">ServerTokens</a></code></li>
4383 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4384 <div class="directive-section"><h2><a name="ServerTokens" id="ServerTokens">ServerTokens</a> <a name="servertokens" id="servertokens">Directive</a></h2>
4385 <table class="directive">
4386 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the <code>Server</code> HTTP response
4388 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerTokens Major|Minor|Min[imal]|Prod[uctOnly]|OS|Full</code></td></tr>
4389 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerTokens Full</code></td></tr>
4390 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4391 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4392 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4394 <p>This directive controls whether <code>Server</code> response
4395 header field which is sent back to clients includes a
4396 description of the generic OS-type of the server as well as
4397 information about compiled-in modules.</p>
4400 <dt><code>ServerTokens Full</code> (or not specified)</dt>
4402 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4403 (Unix) PHP/4.2.2 MyMod/1.2</code></dd>
4405 <dt><code>ServerTokens Prod[uctOnly]</code></dt>
4407 <dd>Server sends (<em>e.g.</em>): <code>Server:
4410 <dt><code>ServerTokens Major</code></dt>
4412 <dd>Server sends (<em>e.g.</em>): <code>Server:
4413 Apache/2</code></dd>
4415 <dt><code>ServerTokens Minor</code></dt>
4417 <dd>Server sends (<em>e.g.</em>): <code>Server:
4418 Apache/2.4</code></dd>
4420 <dt><code>ServerTokens Min[imal]</code></dt>
4422 <dd>Server sends (<em>e.g.</em>): <code>Server:
4423 Apache/2.4.2</code></dd>
4425 <dt><code>ServerTokens OS</code></dt>
4427 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4432 <p>This setting applies to the entire server, and cannot be
4433 enabled or disabled on a virtualhost-by-virtualhost basis.</p>
4435 <p>After version 2.0.44, this directive also controls the
4436 information presented by the <code class="directive"><a href="#serversignature">ServerSignature</a></code> directive.</p>
4438 <div class="note">Setting <code class="directive">ServerTokens</code> to less than
4439 <code>minimal</code> is not recommended because it makes it more
4440 difficult to debug interoperational problems. Also note that
4441 disabling the Server: header does nothing at all to make your
4442 server more secure. The idea of "security through obscurity"
4443 is a myth and leads to a false sense of safety.</div>
4447 <li><code class="directive"><a href="#serversignature">ServerSignature</a></code></li>
4450 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4451 <div class="directive-section"><h2><a name="SetHandler" id="SetHandler">SetHandler</a> <a name="sethandler" id="sethandler">Directive</a></h2>
4452 <table class="directive">
4453 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be processed by a
4455 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetHandler <var>handler-name</var>|none|<var>expression</var></code></td></tr>
4456 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4457 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4458 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4459 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4460 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4462 <p>When placed into an <code>.htaccess</code> file or a
4463 <code class="directive"><a href="#directory"><Directory></a></code> or
4464 <code class="directive"><a href="#location"><Location></a></code>
4465 section, this directive forces all matching files to be parsed
4466 through the <a href="../handler.html">handler</a> given by
4467 <var>handler-name</var>. For example, if you had a directory you
4468 wanted to be parsed entirely as imagemap rule files, regardless
4469 of extension, you might put the following into an
4470 <code>.htaccess</code> file in that directory:</p>
4472 <pre class="prettyprint lang-config">SetHandler imap-file</pre>
4475 <p>Another example: if you wanted to have the server display a
4476 status report whenever a URL of
4477 <code>http://servername/status</code> was called, you might put
4478 the following into <code>httpd.conf</code>:</p>
4480 <pre class="prettyprint lang-config"><Location "/status">
4481 SetHandler server-status
4482 </Location></pre>
4485 <p>You could also use this directive to configure a particular
4486 handler for files with a particular file extension. For example:</p>
4488 <pre class="prettyprint lang-config"><FilesMatch "\.php$">
4489 SetHandler application/x-httpd-php
4490 </FilesMatch></pre>
4493 <p>String-valued expressions can be used to reference per-request
4494 variables, including backreferences to named regular expressions:</p>
4496 <pre class="prettyprint lang-config"><LocationMatch ^/app/(?<sub>[^/]+)/>
4497 SetHandler "proxy:unix:/var/run/app_%{env:MATCH_sub}.sock|fcgi://localhost:8080"
4498 </LocationMatch></pre>
4501 <p>You can override an earlier defined <code class="directive">SetHandler</code>
4502 directive by using the value <code>None</code>.</p>
4504 <div class="note"><h3>Note</h3>
4505 <p>Because <code class="directive">SetHandler</code> overrides default handlers,
4506 normal behavior such as handling of URLs ending in a slash (/) as
4507 directories or index files is suppressed.</p></div>
4511 <li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li>
4514 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4515 <div class="directive-section"><h2><a name="SetInputFilter" id="SetInputFilter">SetInputFilter</a> <a name="setinputfilter" id="setinputfilter">Directive</a></h2>
4516 <table class="directive">
4517 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process client requests and POST
4519 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetInputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4520 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4521 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4522 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4523 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4525 <p>The <code class="directive">SetInputFilter</code> directive sets the
4526 filter or filters which will process client requests and POST
4527 input when they are received by the server. This is in addition to
4528 any filters defined elsewhere, including the
4529 <code class="directive"><a href="../mod/mod_mime.html#addinputfilter">AddInputFilter</a></code>
4532 <p>If more than one filter is specified, they must be separated
4533 by semicolons in the order in which they should process the
4538 <li><a href="../filter.html">Filters</a> documentation</li>
4541 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4542 <div class="directive-section"><h2><a name="SetOutputFilter" id="SetOutputFilter">SetOutputFilter</a> <a name="setoutputfilter" id="setoutputfilter">Directive</a></h2>
4543 <table class="directive">
4544 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process responses from the
4546 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetOutputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4547 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4548 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4549 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4550 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4552 <p>The <code class="directive">SetOutputFilter</code> directive sets the filters
4553 which will process responses from the server before they are
4554 sent to the client. This is in addition to any filters defined
4555 elsewhere, including the
4556 <code class="directive"><a href="../mod/mod_mime.html#addoutputfilter">AddOutputFilter</a></code>
4559 <p>For example, the following configuration will process all files
4560 in the <code>/www/data/</code> directory for server-side
4563 <pre class="prettyprint lang-config"><Directory "/www/data/">
4564 SetOutputFilter INCLUDES
4565 </Directory></pre>
4568 <p>If more than one filter is specified, they must be separated
4569 by semicolons in the order in which they should process the
4574 <li><a href="../filter.html">Filters</a> documentation</li>
4577 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4578 <div class="directive-section"><h2><a name="TimeOut" id="TimeOut">TimeOut</a> <a name="timeout" id="timeout">Directive</a></h2>
4579 <table class="directive">
4580 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for
4581 certain events before failing a request</td></tr>
4582 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TimeOut <var>seconds</var></code></td></tr>
4583 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TimeOut 60</code></td></tr>
4584 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4585 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4586 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4588 <p>The <code class="directive">TimeOut</code> directive defines the length
4589 of time Apache httpd will wait for I/O in various circumstances:</p>
4592 <li><p>When reading data from the client, the length of time to
4593 wait for a TCP packet to arrive if the read buffer is
4595 <p> For initial data on a new connection, this directive doesn't
4596 take effect until after any configured <code class="directive"><a href="#acceptfilter">
4597 AcceptFilter</a></code> has passed the new connection to the server.</p>
4600 <li>When writing data to the client, the length of time to wait
4601 for an acknowledgement of a packet if the send buffer is
4604 <li>In <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code> and <code class="module"><a href="../mod/mod_cgid.html">mod_cgid</a></code>,
4605 the length of time to wait for output from a CGI script.</li>
4607 <li>In <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>, the length of time to
4608 wait for output from a filtering process.</li>
4610 <li>In <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, the default timeout value if
4611 <code class="directive"><a href="../mod/mod_proxy.html#proxytimeout">ProxyTimeout</a></code> is not
4617 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4618 <div class="directive-section"><h2><a name="TraceEnable" id="TraceEnable">TraceEnable</a> <a name="traceenable" id="traceenable">Directive</a></h2>
4619 <table class="directive">
4620 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines the behavior on <code>TRACE</code> requests</td></tr>
4621 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TraceEnable <var>[on|off|extended]</var></code></td></tr>
4622 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TraceEnable on</code></td></tr>
4623 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4624 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4625 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4627 <p>This directive overrides the behavior of <code>TRACE</code> for both
4628 the core server and <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. The default
4629 <code>TraceEnable on</code> permits <code>TRACE</code> requests per
4630 RFC 2616, which disallows any request body to accompany the request.
4631 <code>TraceEnable off</code> causes the core server and
4632 <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> to return a <code>405</code> (Method not
4633 allowed) error to the client.</p>
4635 <p>Finally, for testing and diagnostic purposes only, request
4636 bodies may be allowed using the non-compliant <code>TraceEnable
4637 extended</code> directive. The core (as an origin server) will
4638 restrict the request body to 64Kb (plus 8Kb for chunk headers if
4639 <code>Transfer-Encoding: chunked</code> is used). The core will
4640 reflect the full headers and all chunk headers with the response
4641 body. As a proxy server, the request body is not restricted to 64Kb.</p>
4643 <div class="note"><h3>Note</h3>
4645 <p>Despite claims to the contrary, enabling the <code>TRACE</code>
4646 method does not expose any security vulnerability in Apache httpd.
4647 The <code>TRACE</code> method is defined by the HTTP/1.1
4648 specification and implementations are expected to support it.</p>
4653 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4654 <div class="directive-section"><h2><a name="UnDefine" id="UnDefine">UnDefine</a> <a name="undefine" id="undefine">Directive</a></h2>
4655 <table class="directive">
4656 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Undefine the existence of a variable</td></tr>
4657 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UnDefine <var>parameter-name</var></code></td></tr>
4658 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4659 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4660 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4662 <p>Undoes the effect of a <code class="directive"><a href="#define">Define</a></code> or
4663 of passing a <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</p>
4664 <p>This directive can be used to toggle the use of <code class="directive"><a href="#ifdefine"><IfDefine></a></code> sections without needing to alter
4665 <code>-D</code> arguments in any startup scripts.</p>
4666 <p>While this directive is supported in virtual host context,
4667 the changes it makes are visible to any later configuration
4668 directives, beyond any enclosing virtual host.</p>
4671 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4672 <div class="directive-section"><h2><a name="UseCanonicalName" id="UseCanonicalName">UseCanonicalName</a> <a name="usecanonicalname" id="usecanonicalname">Directive</a></h2>
4673 <table class="directive">
4674 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own name and
4676 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalName On|Off|DNS</code></td></tr>
4677 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalName Off</code></td></tr>
4678 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4679 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4680 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4682 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4683 URL -- that is, a URL that refers back to the same server. With
4684 <code>UseCanonicalName On</code> Apache httpd will use the hostname and port
4685 specified in the <code class="directive"><a href="#servername">ServerName</a></code>
4686 directive to construct the canonical name for the server. This name
4687 is used in all self-referential URLs, and for the values of
4688 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in CGIs.</p>
4690 <p>With <code>UseCanonicalName Off</code> Apache httpd will form
4691 self-referential URLs using the hostname and port supplied by
4692 the client if any are supplied (otherwise it will use the
4693 canonical name, as defined above). These values are the same
4694 that are used to implement <a href="../vhosts/name-based.html">name-based virtual hosts</a>
4695 and are available with the same clients. The CGI variables
4696 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
4697 constructed from the client supplied values as well.</p>
4699 <p>An example where this may be useful is on an intranet server
4700 where you have users connecting to the machine using short
4701 names such as <code>www</code>. You'll notice that if the users
4702 type a shortname and a URL which is a directory, such as
4703 <code>http://www/splat</code>, <em>without the trailing
4704 slash</em>, then Apache httpd will redirect them to
4705 <code>http://www.example.com/splat/</code>. If you have
4706 authentication enabled, this will cause the user to have to
4707 authenticate twice (once for <code>www</code> and once again
4708 for <code>www.example.com</code> -- see <a href="http://wiki.apache.org/httpd/FAQ#Why_does_Apache_ask_for_my_password_twice_before_serving_a_file.3F">
4709 the FAQ on this subject for more information</a>). But if
4710 <code class="directive">UseCanonicalName</code> is set <code>Off</code>, then
4711 Apache httpd will redirect to <code>http://www/splat/</code>.</p>
4713 <p>There is a third option, <code>UseCanonicalName DNS</code>,
4714 which is intended for use with mass IP-based virtual hosting to
4715 support ancient clients that do not provide a
4716 <code>Host:</code> header. With this option, Apache httpd does a
4717 reverse DNS lookup on the server IP address that the client
4718 connected to in order to work out self-referential URLs.</p>
4720 <div class="warning"><h3>Warning</h3>
4721 <p>If CGIs make assumptions about the values of <code>SERVER_NAME</code>,
4722 they may be broken by this option. The client is essentially free
4723 to give whatever value they want as a hostname. But if the CGI is
4724 only using <code>SERVER_NAME</code> to construct self-referential URLs,
4725 then it should be just fine.</p>
4730 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4731 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4732 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4735 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4736 <div class="directive-section"><h2><a name="UseCanonicalPhysicalPort" id="UseCanonicalPhysicalPort">UseCanonicalPhysicalPort</a> <a name="usecanonicalphysicalport" id="usecanonicalphysicalport">Directive</a></h2>
4737 <table class="directive">
4738 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own port</td></tr>
4739 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalPhysicalPort On|Off</code></td></tr>
4740 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalPhysicalPort Off</code></td></tr>
4741 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4742 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4743 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4745 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4746 URL -- that is, a URL that refers back to the same server. With
4747 <code>UseCanonicalPhysicalPort On</code>, Apache httpd will, when
4748 constructing the canonical port for the server to honor
4749 the <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> directive,
4750 provide the actual physical port number being used by this request
4751 as a potential port. With <code>UseCanonicalPhysicalPort Off</code>,
4752 Apache httpd will not ever use the actual physical port number, instead
4753 relying on all configured information to construct a valid port number.</p>
4755 <div class="note"><h3>Note</h3>
4756 <p>The ordering of the lookup when the physical port is used is as
4759 <dt><code>UseCanonicalName On</code></dt>
4762 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4763 <li>Physical port</li>
4764 <li>Default port</li>
4767 <dt><code>UseCanonicalName Off | DNS</code></dt>
4770 <li>Parsed port from <code>Host:</code> header</li>
4771 <li>Physical port</li>
4772 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4773 <li>Default port</li>
4778 <p>With <code>UseCanonicalPhysicalPort Off</code>, the
4779 physical ports are removed from the ordering.</p>
4785 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4786 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4787 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4790 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4791 <div class="directive-section"><h2><a name="VirtualHost" id="VirtualHost"><VirtualHost></a> <a name="virtualhost" id="virtualhost">Directive</a></h2>
4792 <table class="directive">
4793 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only to a specific
4794 hostname or IP address</td></tr>
4795 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><VirtualHost
4796 <var>addr</var>[:<var>port</var>] [<var>addr</var>[:<var>port</var>]]
4797 ...> ... </VirtualHost></code></td></tr>
4798 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4799 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4800 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4802 <p><code class="directive"><VirtualHost></code> and
4803 <code></VirtualHost></code> are used to enclose a group of
4804 directives that will apply only to a particular virtual host. Any
4805 directive that is allowed in a virtual host context may be
4806 used. When the server receives a request for a document on a
4807 particular virtual host, it uses the configuration directives
4808 enclosed in the <code class="directive"><VirtualHost></code>
4809 section. <var>Addr</var> can be any of the following, optionally followed by
4810 a colon and a port number (or *):</p>
4813 <li>The IP address of the virtual host;</li>
4815 <li>A fully qualified domain name for the IP address of the
4816 virtual host (not recommended);</li>
4818 <li>The character <code>*</code>, which acts as a wildcard and matches
4819 any IP address.</li>
4821 <li>The string <code>_default_</code>, which is an alias for <code>*</code></li>
4825 <pre class="prettyprint lang-config"><VirtualHost 10.1.2.3:80>
4826 ServerAdmin webmaster@host.example.com
4827 DocumentRoot "/www/docs/host.example.com"
4828 ServerName host.example.com
4829 ErrorLog "logs/host.example.com-error_log"
4830 TransferLog "logs/host.example.com-access_log"
4831 </VirtualHost></pre>
4835 <p>IPv6 addresses must be specified in square brackets because
4836 the optional port number could not be determined otherwise. An
4837 IPv6 example is shown below:</p>
4839 <pre class="prettyprint lang-config"><VirtualHost [2001:db8::a00:20ff:fea7:ccea]:80>
4840 ServerAdmin webmaster@host.example.com
4841 DocumentRoot "/www/docs/host.example.com"
4842 ServerName host.example.com
4843 ErrorLog "logs/host.example.com-error_log"
4844 TransferLog "logs/host.example.com-access_log"
4845 </VirtualHost></pre>
4848 <p>Each Virtual Host must correspond to a different IP address,
4849 different port number, or a different host name for the server,
4850 in the former case the server machine must be configured to
4851 accept IP packets for multiple addresses. (If the machine does
4852 not have multiple network interfaces, then this can be
4853 accomplished with the <code>ifconfig alias</code> command -- if
4854 your OS supports it).</p>
4856 <div class="note"><h3>Note</h3>
4857 <p>The use of <code class="directive"><VirtualHost></code> does
4858 <strong>not</strong> affect what addresses Apache httpd listens on. You
4859 may need to ensure that Apache httpd is listening on the correct addresses
4860 using <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>.</p>
4863 <p>A <code class="directive"><a href="#servername">ServerName</a></code> should be
4864 specified inside each <code class="directive"><VirtualHost></code> block. If it is absent, the
4865 <code class="directive"><a href="#servername">ServerName</a></code> from the "main"
4866 server configuration will be inherited.</p>
4868 <p>When a request is received, the server first maps it to the best matching
4869 <code class="directive"><VirtualHost></code> based on the local
4870 IP address and port combination only. Non-wildcards have a higher
4871 precedence. If no match based on IP and port occurs at all, the
4872 "main" server configuration is used.</p>
4874 <p>If multiple virtual hosts contain the best matching IP address and port,
4875 the server selects from these virtual hosts the best match based on the
4876 requested hostname. If no matching name-based virtual host is found,
4877 then the first listed virtual host that matched the IP address will be
4878 used. As a consequence, the first listed virtual host for a given IP address
4879 and port combination is the default virtual host for that IP and port
4882 <div class="warning"><h3>Security</h3>
4883 <p>See the <a href="../misc/security_tips.html">security tips</a>
4884 document for details on why your security could be compromised if the
4885 directory where log files are stored is writable by anyone other
4886 than the user that starts the server.</p>
4891 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4892 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4893 Apache HTTP Server</a></li>
4894 <li><a href="../bind.html">Setting
4895 which addresses and ports Apache HTTP Server uses</a></li>
4896 <li><a href="../sections.html">How <Directory>, <Location>
4897 and <Files> sections work</a> for an explanation of how these
4898 different sections are combined when a request is received</li>
4901 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4902 <div class="directive-section"><h2><a name="Warning" id="Warning">Warning</a> <a name="warning" id="warning">Directive</a></h2>
4903 <table class="directive">
4904 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Warn from configuration parsing with a custom message</td></tr>
4905 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Warning <var>message</var></code></td></tr>
4906 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4907 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4908 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4909 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4911 <p>If an issue can be detected from within the configuration, this
4912 directive can be used to generate a custom warning message. The
4913 configuration parsing is not halted. The typical use is to check
4914 whether some user define options are set, and warn if not.</p>
4916 <pre class="prettyprint lang-config"># Example
4917 # tell when ReverseProxy is not set
4918 <IfDefine !ReverseProxy>
4919 Warning "reverse proxy is not started, hope this is okay!"
4922 <IfDefine ReverseProxy>
4923 # define custom proxy configuration
4924 </IfDefine></pre>
4930 <div class="bottomlang">
4931 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
4932 <a href="../en/mod/core.html" title="English"> en </a> |
4933 <a href="../es/mod/core.html" hreflang="es" rel="alternate" title="Español"> es </a> |
4934 <a href="../fr/mod/core.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
4935 <a href="../ja/mod/core.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
4936 <a href="../tr/mod/core.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
4937 </div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
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