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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] [Allow0.9|Require1.0]
2034 [StrictWhitespace|LenientWhitespace] [RegisteredMethods|LenientMethods]</code></td></tr>
2035 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HTTPProtocolOptions Strict Allow0.9 LenientWhitespace
2036 LenientMethods</code></td></tr>
2037 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2038 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2039 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2040 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.2.32 or 2.4.24 and later</td></tr>
2042 <p>This directive changes the rules applied to the HTTP Request Line
2043 (<a href="https://tools.ietf.org/html/rfc7230#section-3.1.1">RFC 7230 §3.1.1</a>) and the HTTP Request Header Fields
2044 (<a href="https://tools.ietf.org/html/rfc7230#section-3.2">RFC 7230 §3.2</a>), which are now applied by default or using
2045 the <code>Strict</code> option. Due to legacy modules, applications or
2046 custom user-agents which must be deperecated, an <code>Unsafe</code>
2047 option has been added to revert to the legacy behavior. These rules are
2048 applied prior to request processing, so must be configured at the global
2049 or default (first) matching virtual host section, by interface and not
2050 by name, to be honored.</p>
2052 <p>Prior to the introduction of this directive, the Apache HTTP Server
2053 request message parsers were tolerant of a number of forms of input
2054 which did not conform to the protocol.
2055 <a href="https://tools.ietf.org/html/rfc7230#section-9.4">RFC 7230 §9.4 Request Splitting</a> and
2056 <a href="https://tools.ietf.org/html/rfc7230#section-9.5">§9.5 Response Smuggling</a> call out only two of the potential
2057 risks of accepting non-conformant request messages. As of the introduction
2058 of this directive, all grammer rules of the specification are enforced in
2059 the default <code>Strict</code> operating mode.</p>
2061 <p>Users are strongly cautioned against toggling the <code>Unsafe</code>
2062 mode of operation for these reasons, most especially on outward-facing,
2063 publicly accessible server deployments. Reviewing the messages within the
2064 <code class="directive">ErrorLog</code>, configured with
2065 <code class="directive">LogLevel</code> <code>info</code> level or below,
2066 can help identify such faulty requests along with their origin.
2067 Users should pay particular attention to any 400 responses in the access
2068 log for indiciations that valid requests are unexpectedly rejected.</p>
2070 <p><a href="https://tools.ietf.org/html/rfc2616#section-19.6">RFC 2616 §19.6</a> "Compatibility With Previous Versions" had
2071 encouraged HTTP servers to support legacy HTTP/0.9 requests. RFC 7230
2072 superceeds this with "The expectation to support HTTP/0.9 requests has
2073 been removed" and offers additional comments in
2074 <a href="https://tools.ietf.org/html/rfc7230#appendix-A">RFC 2616 Appendix A</a>. The <code>Require1.0</code> option allows
2075 the user to remove support of the default <code>Allow0.9</code> option's
2078 <p><a href="https://tools.ietf.org/html/rfc7230#section-3.5">RFC 7230 §3.5</a> "Message Parsing Robustness" permits, and
2079 identifies potential risks of parsing messages containing non-space
2080 character whitespace. While the spec defines that exactly one space
2081 seperates the URI from the method, and the protocol from the URI, the
2082 Apache HTTP Server has traditionally been lenient in accepting other
2083 whitespace including one or more horizontal-tab or space characters.
2084 The default <code>LenientWhitespace</code> continues to accept such
2085 requests from non-conforming user-agents, but the administrator may toggle
2086 the <code>StrictWhitespace</code> option to insist on precisely two spaces
2087 in the request line. Other whitespace including vertical-tab, form-feed,
2088 and carriage-return characters are rejected and cannot be supported.</p>
2090 <p><a href="https://tools.ietf.org/html/rfc7231#section-4.1">RFC 7231 §4.1</a> "Request Methods" "Overview" requires that
2091 origin servers shall respond with an error when an unsupported method
2092 is encountered in the request line. This already happens when the
2093 <code>LenientMethods</code> option is used, but administrators may wish
2094 to toggle the <code>RegisteredMethods</code> option and register all
2095 permitted method tokens using the <code class="directive">RegisterHttpMethod</code>
2096 directive, particularly if the <code>Unsafe</code> option has been toggled.
2097 The <code>RegisteredMethods</code> option should <strong>not</strong>
2098 be toggled for forward proxy hosts, as the methods supported by the
2099 origin servers are unknown to the proxy server.</p>
2102 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2103 <div class="directive-section"><h2><a name="If" id="If"><If></a> <a name="if" id="if">Directive</a></h2>
2104 <table class="directive">
2105 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is
2106 satisfied by a request at runtime</td></tr>
2107 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><If <var>expression</var>> ... </If></code></td></tr>
2108 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2109 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2110 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2111 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2113 <p>The <code class="directive"><If></code> directive
2114 evaluates an expression at runtime, and applies the enclosed
2115 directives if and only if the expression evaluates to true.
2118 <pre class="prettyprint lang-config"><If "-z req('Host')"></pre>
2121 <p>would match HTTP/1.0 requests without a <var>Host:</var> header.
2122 Expressions may contain various shell-like operators for string
2123 comparison (<code>==</code>, <code>!=</code>, <code><</code>, ...),
2124 integer comparison (<code>-eq</code>, <code>-ne</code>, ...),
2125 and others (<code>-n</code>, <code>-z</code>, <code>-f</code>, ...).
2126 It is also possible to use regular expressions, </p>
2128 <pre class="prettyprint lang-config"><If "%{QUERY_STRING} =~ /(delete|commit)=.*?elem/"></pre>
2131 <p>shell-like pattern matches and many other operations. These operations
2132 can be done on request headers (<code>req</code>), environment variables
2133 (<code>env</code>), and a large number of other properties. The full
2134 documentation is available in <a href="../expr.html">Expressions in
2135 Apache HTTP Server</a>.</p>
2137 <p>Only directives that support the <a href="directive-dict.html#Context">directory context</a> can be used within this configuration section.</p>
2139 <div class="warning">
2140 Certain variables, such as <code>CONTENT_TYPE</code> and other
2141 response headers, are set after <If> conditions have already
2142 been evaluated, and so will not be available to use in this
2149 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
2150 for a complete reference and more examples.</li>
2151 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
2152 <li><code class="directive"><a href="#else"><Else></a></code></li>
2153 <li><a href="../sections.html">How <Directory>, <Location>,
2154 <Files> sections work</a> for an explanation of how these
2155 different sections are combined when a request is received.
2156 <code class="directive"><If></code>,
2157 <code class="directive"><ElseIf></code>, and
2158 <code class="directive"><Else></code> are applied last.</li>
2161 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2162 <div class="directive-section"><h2><a name="IfDefine" id="IfDefine"><IfDefine></a> <a name="ifdefine" id="ifdefine">Directive</a></h2>
2163 <table class="directive">
2164 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that will be processed only
2165 if a test is true at startup</td></tr>
2166 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfDefine [!]<var>parameter-name</var>> ...
2167 </IfDefine></code></td></tr>
2168 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2169 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2170 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2171 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2173 <p>The <code><IfDefine <var>test</var>>...</IfDefine>
2174 </code> section is used to mark directives that are conditional. The
2175 directives within an <code class="directive"><IfDefine></code>
2176 section are only processed if the <var>test</var> is true. If <var>
2177 test</var> is false, everything between the start and end markers is
2180 <p>The <var>test</var> in the <code class="directive"><IfDefine></code> section directive can be one of two forms:</p>
2183 <li><var>parameter-name</var></li>
2185 <li><code>!</code><var>parameter-name</var></li>
2188 <p>In the former case, the directives between the start and end
2189 markers are only processed if the parameter named
2190 <var>parameter-name</var> is defined. The second format reverses
2191 the test, and only processes the directives if
2192 <var>parameter-name</var> is <strong>not</strong> defined.</p>
2194 <p>The <var>parameter-name</var> argument is a define as given on the
2195 <code class="program"><a href="../programs/httpd.html">httpd</a></code> command line via <code>-D<var>parameter</var>
2196 </code> at the time the server was started or by the <code class="directive"><a href="#define">Define</a></code> directive.</p>
2198 <p><code class="directive"><IfDefine></code> sections are
2199 nest-able, which can be used to implement simple
2200 multiple-parameter tests. Example:</p>
2202 <div class="example"><p><code>httpd -DReverseProxy -DUseCache -DMemCache ...</code></p></div>
2203 <pre class="prettyprint lang-config"><IfDefine ReverseProxy>
2204 LoadModule proxy_module modules/mod_proxy.so
2205 LoadModule proxy_http_module modules/mod_proxy_http.so
2206 <IfDefine UseCache>
2207 LoadModule cache_module modules/mod_cache.so
2208 <IfDefine MemCache>
2209 LoadModule mem_cache_module modules/mod_mem_cache.so
2211 <IfDefine !MemCache>
2212 LoadModule cache_disk_module modules/mod_cache_disk.so
2215 </IfDefine></pre>
2219 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2220 <div class="directive-section"><h2><a name="IfModule" id="IfModule"><IfModule></a> <a name="ifmodule" id="ifmodule">Directive</a></h2>
2221 <table class="directive">
2222 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that are processed conditional on the
2223 presence or absence of a specific module</td></tr>
2224 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfModule [!]<var>module-file</var>|<var>module-identifier</var>> ...
2225 </IfModule></code></td></tr>
2226 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2227 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2228 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2229 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2231 <p>The <code><IfModule <var>test</var>>...</IfModule></code>
2232 section is used to mark directives that are conditional on the presence of
2233 a specific module. The directives within an <code class="directive"><IfModule></code> section are only processed if the <var>test</var>
2234 is true. If <var>test</var> is false, everything between the start and
2235 end markers is ignored.</p>
2237 <p>The <var>test</var> in the <code class="directive"><IfModule></code> section directive can be one of two forms:</p>
2240 <li><var>module</var></li>
2242 <li>!<var>module</var></li>
2245 <p>In the former case, the directives between the start and end
2246 markers are only processed if the module named <var>module</var>
2247 is included in Apache httpd -- either compiled in or
2248 dynamically loaded using <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code>. The second format reverses the test,
2249 and only processes the directives if <var>module</var> is
2250 <strong>not</strong> included.</p>
2252 <p>The <var>module</var> argument can be either the module identifier or
2253 the file name of the module, at the time it was compiled. For example,
2254 <code>rewrite_module</code> is the identifier and
2255 <code>mod_rewrite.c</code> is the file name. If a module consists of
2256 several source files, use the name of the file containing the string
2257 <code>STANDARD20_MODULE_STUFF</code>.</p>
2259 <p><code class="directive"><IfModule></code> sections are
2260 nest-able, which can be used to implement simple multiple-module
2263 <div class="note">This section should only be used if you need to have one
2264 configuration file that works whether or not a specific module
2265 is available. In normal operation, directives need not be
2266 placed in <code class="directive"><IfModule></code>
2270 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2271 <div class="directive-section"><h2><a name="Include" id="Include">Include</a> <a name="include" id="include">Directive</a></h2>
2272 <table class="directive">
2273 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2274 the server configuration files</td></tr>
2275 <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>
2276 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2277 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2278 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2279 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directory
2280 wildcard matching available in 2.3.6 and later</td></tr>
2282 <p>This directive allows inclusion of other configuration files
2283 from within the server configuration files.</p>
2285 <p>Shell-style (<code>fnmatch()</code>) wildcard characters can be used
2286 in the filename or directory parts of the path to include several files
2287 at once, in alphabetical order. In addition, if
2288 <code class="directive">Include</code> points to a directory, rather than a file,
2289 Apache httpd will read all files in that directory and any subdirectory.
2290 However, including entire directories is not recommended, because it is
2291 easy to accidentally leave temporary files in a directory that can cause
2292 <code class="program"><a href="../programs/httpd.html">httpd</a></code> to fail. Instead, we encourage you to use the
2293 wildcard syntax shown below, to include files that match a particular
2294 pattern, such as *.conf, for example.</p>
2296 <p>The <code class="directive"><a href="#include">Include</a></code> directive will
2297 <strong>fail with an error</strong> if a wildcard expression does not
2298 match any file. The <code class="directive"><a href="#includeoptional">IncludeOptional</a></code>
2299 directive can be used if non-matching wildcards should be ignored.</p>
2301 <p>The file path specified may be an absolute path, or may be relative
2302 to the <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory.</p>
2306 <pre class="prettyprint lang-config">Include /usr/local/apache2/conf/ssl.conf
2307 Include /usr/local/apache2/conf/vhosts/*.conf</pre>
2310 <p>Or, providing paths relative to your <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory:</p>
2312 <pre class="prettyprint lang-config">Include conf/ssl.conf
2313 Include conf/vhosts/*.conf</pre>
2316 <p>Wildcards may be included in the directory or file portion of the
2317 path. This example will fail if there is no subdirectory in conf/vhosts
2318 that contains at least one *.conf file:</p>
2320 <pre class="prettyprint lang-config">Include conf/vhosts/*/*.conf</pre>
2323 <p>Alternatively, the following command will just be ignored in case of
2324 missing files or directories:</p>
2326 <pre class="prettyprint lang-config">IncludeOptional conf/vhosts/*/*.conf</pre>
2332 <li><code class="directive"><a href="#includeoptional">IncludeOptional</a></code></li>
2333 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
2336 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2337 <div class="directive-section"><h2><a name="IncludeOptional" id="IncludeOptional">IncludeOptional</a> <a name="includeoptional" id="includeoptional">Directive</a></h2>
2338 <table class="directive">
2339 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2340 the server configuration files</td></tr>
2341 <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>
2342 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2343 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2344 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2345 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in 2.3.6 and later</td></tr>
2347 <p>This directive allows inclusion of other configuration files
2348 from within the server configuration files. It works identically to the
2349 <code class="directive"><a href="#include">Include</a></code> directive, with the
2350 exception that if wildcards do not match any file or directory, the
2351 <code class="directive"><a href="#includeoptional">IncludeOptional</a></code> directive will be
2352 silently ignored instead of causing an error.</p>
2356 <li><code class="directive"><a href="#include">Include</a></code></li>
2357 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
2360 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2361 <div class="directive-section"><h2><a name="KeepAlive" id="KeepAlive">KeepAlive</a> <a name="keepalive" id="keepalive">Directive</a></h2>
2362 <table class="directive">
2363 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables HTTP persistent connections</td></tr>
2364 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAlive On|Off</code></td></tr>
2365 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAlive On</code></td></tr>
2366 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2367 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2368 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2370 <p>The Keep-Alive extension to HTTP/1.0 and the persistent
2371 connection feature of HTTP/1.1 provide long-lived HTTP sessions
2372 which allow multiple requests to be sent over the same TCP
2373 connection. In some cases this has been shown to result in an
2374 almost 50% speedup in latency times for HTML documents with
2375 many images. To enable Keep-Alive connections, set
2376 <code>KeepAlive On</code>.</p>
2378 <p>For HTTP/1.0 clients, Keep-Alive connections will only be
2379 used if they are specifically requested by a client. In
2380 addition, a Keep-Alive connection with an HTTP/1.0 client can
2381 only be used when the length of the content is known in
2382 advance. This implies that dynamic content such as CGI output,
2383 SSI pages, and server-generated directory listings will
2384 generally not use Keep-Alive connections to HTTP/1.0 clients.
2385 For HTTP/1.1 clients, persistent connections are the default
2386 unless otherwise specified. If the client requests it, chunked
2387 encoding will be used in order to send content of unknown
2388 length over persistent connections.</p>
2390 <p>When a client uses a Keep-Alive connection, it will be counted
2391 as a single "request" for the <code class="directive"><a href="../mod/mpm_common.html#maxconnectionsperchild">MaxConnectionsPerChild</a></code> directive, regardless
2392 of how many requests are sent using the connection.</p>
2396 <li><code class="directive"><a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></code></li>
2399 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2400 <div class="directive-section"><h2><a name="KeepAliveTimeout" id="KeepAliveTimeout">KeepAliveTimeout</a> <a name="keepalivetimeout" id="keepalivetimeout">Directive</a></h2>
2401 <table class="directive">
2402 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for subsequent
2403 requests on a persistent connection</td></tr>
2404 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAliveTimeout <var>num</var>[ms]</code></td></tr>
2405 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAliveTimeout 5</code></td></tr>
2406 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2407 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2408 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2410 <p>The number of seconds Apache httpd will wait for a subsequent
2411 request before closing the connection. By adding a postfix of ms the
2412 timeout can be also set in milliseconds. Once a request has been
2413 received, the timeout value specified by the
2414 <code class="directive"><a href="#timeout">Timeout</a></code> directive applies.</p>
2416 <p>Setting <code class="directive">KeepAliveTimeout</code> to a high value
2417 may cause performance problems in heavily loaded servers. The
2418 higher the timeout, the more server processes will be kept
2419 occupied waiting on connections with idle clients.</p>
2421 <p>If <code class="directive">KeepAliveTimeout</code> is <strong>not</strong>
2422 set for a name-based virtual host, the value of the first defined
2423 virtual host best matching the local IP and port will be used.</p>
2426 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2427 <div class="directive-section"><h2><a name="Limit" id="Limit"><Limit></a> <a name="limit" id="limit">Directive</a></h2>
2428 <table class="directive">
2429 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict enclosed access controls to only certain HTTP
2431 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Limit <var>method</var> [<var>method</var>] ... > ...
2432 </Limit></code></td></tr>
2433 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2434 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2435 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2436 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2438 <p>Access controls are normally effective for
2439 <strong>all</strong> access methods, and this is the usual
2440 desired behavior. <strong>In the general case, access control
2441 directives should not be placed within a
2442 <code class="directive"><Limit></code> section.</strong></p>
2444 <p>The purpose of the <code class="directive"><Limit></code>
2445 directive is to restrict the effect of the access controls to the
2446 nominated HTTP methods. For all other methods, the access
2447 restrictions that are enclosed in the <code class="directive"><Limit></code> bracket <strong>will have no
2448 effect</strong>. The following example applies the access control
2449 only to the methods <code>POST</code>, <code>PUT</code>, and
2450 <code>DELETE</code>, leaving all other methods unprotected:</p>
2452 <pre class="prettyprint lang-config"><Limit POST PUT DELETE>
2454 </Limit></pre>
2457 <p>The method names listed can be one or more of: <code>GET</code>,
2458 <code>POST</code>, <code>PUT</code>, <code>DELETE</code>,
2459 <code>CONNECT</code>, <code>OPTIONS</code>,
2460 <code>PATCH</code>, <code>PROPFIND</code>, <code>PROPPATCH</code>,
2461 <code>MKCOL</code>, <code>COPY</code>, <code>MOVE</code>,
2462 <code>LOCK</code>, and <code>UNLOCK</code>. <strong>The method name is
2463 case-sensitive.</strong> If <code>GET</code> is used, it will also
2464 restrict <code>HEAD</code> requests. The <code>TRACE</code> method
2465 cannot be limited (see <code class="directive"><a href="#traceenable">TraceEnable</a></code>).</p>
2467 <div class="warning">A <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section should always be
2468 used in preference to a <code class="directive"><Limit></code>
2469 section when restricting access, since a <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section provides protection
2470 against arbitrary methods.</div>
2472 <p>The <code class="directive"><Limit></code> and
2473 <code class="directive"><a href="#limitexcept"><LimitExcept></a></code>
2474 directives may be nested. In this case, each successive level of
2475 <code class="directive"><Limit></code> or <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> directives must
2476 further restrict the set of methods to which access controls apply.</p>
2478 <div class="warning">When using
2479 <code class="directive"><Limit></code> or
2480 <code class="directive"><LimitExcept></code> directives with
2481 the <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directive,
2482 note that the first <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code>
2483 to succeed authorizes the request, regardless of the presence of other
2484 <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directives.</div>
2486 <p>For example, given the following configuration, all users will
2487 be authorized for <code>POST</code> requests, and the
2488 <code>Require group editors</code> directive will be ignored
2491 <pre class="prettyprint lang-config"><LimitExcept GET>
2493 </LimitExcept>
2495 Require group editors
2496 </Limit></pre>
2500 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2501 <div class="directive-section"><h2><a name="LimitExcept" id="LimitExcept"><LimitExcept></a> <a name="limitexcept" id="limitexcept">Directive</a></h2>
2502 <table class="directive">
2503 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict access controls to all HTTP methods
2504 except the named ones</td></tr>
2505 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LimitExcept <var>method</var> [<var>method</var>] ... > ...
2506 </LimitExcept></code></td></tr>
2507 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2508 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2509 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2510 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2512 <p><code class="directive"><LimitExcept></code> and
2513 <code></LimitExcept></code> are used to enclose
2514 a group of access control directives which will then apply to any
2515 HTTP access method <strong>not</strong> listed in the arguments;
2516 i.e., it is the opposite of a <code class="directive"><a href="#limit"><Limit></a></code> section and can be used to control
2517 both standard and nonstandard/unrecognized methods. See the
2518 documentation for <code class="directive"><a href="#limit"><Limit></a></code> for more details.</p>
2522 <pre class="prettyprint lang-config"><LimitExcept POST GET>
2524 </LimitExcept></pre>
2529 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2530 <div class="directive-section"><h2><a name="LimitInternalRecursion" id="LimitInternalRecursion">LimitInternalRecursion</a> <a name="limitinternalrecursion" id="limitinternalrecursion">Directive</a></h2>
2531 <table class="directive">
2532 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine maximum number of internal redirects and nested
2533 subrequests</td></tr>
2534 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitInternalRecursion <var>number</var> [<var>number</var>]</code></td></tr>
2535 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitInternalRecursion 10</code></td></tr>
2536 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2537 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2538 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2540 <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
2541 redirects the original request to a CGI script. A subrequest is Apache httpd's
2542 mechanism to find out what would happen for some URI if it were requested.
2543 For example, <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> uses subrequests to look for the
2544 files listed in the <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
2547 <p><code class="directive">LimitInternalRecursion</code> prevents the server
2548 from crashing when entering an infinite loop of internal redirects or
2549 subrequests. Such loops are usually caused by misconfigurations.</p>
2551 <p>The directive stores two different limits, which are evaluated on
2552 per-request basis. The first <var>number</var> is the maximum number of
2553 internal redirects that may follow each other. The second <var>number</var>
2554 determines how deeply subrequests may be nested. If you specify only one
2555 <var>number</var>, it will be assigned to both limits.</p>
2557 <pre class="prettyprint lang-config">LimitInternalRecursion 5</pre>
2561 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2562 <div class="directive-section"><h2><a name="LimitRequestBody" id="LimitRequestBody">LimitRequestBody</a> <a name="limitrequestbody" id="limitrequestbody">Directive</a></h2>
2563 <table class="directive">
2564 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restricts the total size of the HTTP request body sent
2565 from the client</td></tr>
2566 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestBody <var>bytes</var></code></td></tr>
2567 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestBody 0</code></td></tr>
2568 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2569 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2570 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2571 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2573 <p>This directive specifies the number of <var>bytes</var> from 0
2574 (meaning unlimited) to 2147483647 (2GB) that are allowed in a
2575 request body. See the note below for the limited applicability
2576 to proxy requests.</p>
2578 <p>The <code class="directive">LimitRequestBody</code> directive allows
2579 the user to set a limit on the allowed size of an HTTP request
2580 message body within the context in which the directive is given
2581 (server, per-directory, per-file or per-location). If the client
2582 request exceeds that limit, the server will return an error
2583 response instead of servicing the request. The size of a normal
2584 request message body will vary greatly depending on the nature of
2585 the resource and the methods allowed on that resource. CGI scripts
2586 typically use the message body for retrieving form information.
2587 Implementations of the <code>PUT</code> method will require
2588 a value at least as large as any representation that the server
2589 wishes to accept for that resource.</p>
2591 <p>This directive gives the server administrator greater
2592 control over abnormal client request behavior, which may be
2593 useful for avoiding some forms of denial-of-service
2596 <p>If, for example, you are permitting file upload to a particular
2597 location and wish to limit the size of the uploaded file to 100K,
2598 you might use the following directive:</p>
2600 <pre class="prettyprint lang-config">LimitRequestBody 102400</pre>
2603 <div class="note"><p>For a full description of how this directive is interpreted by
2604 proxy requests, see the <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> documentation.</p>
2609 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2610 <div class="directive-section"><h2><a name="LimitRequestFields" id="LimitRequestFields">LimitRequestFields</a> <a name="limitrequestfields" id="limitrequestfields">Directive</a></h2>
2611 <table class="directive">
2612 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of HTTP request header fields that
2613 will be accepted from the client</td></tr>
2614 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFields <var>number</var></code></td></tr>
2615 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFields 100</code></td></tr>
2616 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2617 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2618 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2620 <p><var>Number</var> is an integer from 0 (meaning unlimited) to
2621 32767. The default value is defined by the compile-time
2622 constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
2625 <p>The <code class="directive">LimitRequestFields</code> directive allows
2626 the server administrator to modify the limit on the number of
2627 request header fields allowed in an HTTP request. A server needs
2628 this value to be larger than the number of fields that a normal
2629 client request might include. The number of request header fields
2630 used by a client rarely exceeds 20, but this may vary among
2631 different client implementations, often depending upon the extent
2632 to which a user has configured their browser to support detailed
2633 content negotiation. Optional HTTP extensions are often expressed
2634 using request header fields.</p>
2636 <p>This directive gives the server administrator greater
2637 control over abnormal client request behavior, which may be
2638 useful for avoiding some forms of denial-of-service attacks.
2639 The value should be increased if normal clients see an error
2640 response from the server that indicates too many fields were
2641 sent in the request.</p>
2645 <pre class="prettyprint lang-config">LimitRequestFields 50</pre>
2648 <div class="warning"><h3>Warning</h3>
2649 <p> When name-based virtual hosting is used, the value for this
2650 directive is taken from the default (first-listed) virtual host for the
2651 local IP and port combination.</p>
2656 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2657 <div class="directive-section"><h2><a name="LimitRequestFieldSize" id="LimitRequestFieldSize">LimitRequestFieldSize</a> <a name="limitrequestfieldsize" id="limitrequestfieldsize">Directive</a></h2>
2658 <table class="directive">
2659 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of the HTTP request header allowed from the
2661 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFieldSize <var>bytes</var></code></td></tr>
2662 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFieldSize 8190</code></td></tr>
2663 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2664 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2665 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2667 <p>This directive specifies the number of <var>bytes</var>
2668 that will be allowed in an HTTP request header.</p>
2670 <p>The <code class="directive">LimitRequestFieldSize</code> directive
2671 allows the server administrator to set the limit
2672 on the allowed size of an HTTP request header field. A server
2673 needs this value to be large enough to hold any one header field
2674 from a normal client request. The size of a normal request header
2675 field will vary greatly among different client implementations,
2676 often depending upon the extent to which a user has configured
2677 their browser to support detailed content negotiation. SPNEGO
2678 authentication headers can be up to 12392 bytes.</p>
2680 <p>This directive gives the server administrator greater
2681 control over abnormal client request behavior, which may be
2682 useful for avoiding some forms of denial-of-service attacks.</p>
2686 <pre class="prettyprint lang-config">LimitRequestFieldSize 4094</pre>
2689 <div class="note">Under normal conditions, the value should not be changed from
2692 <div class="warning"><h3>Warning</h3>
2693 <p> When name-based virtual hosting is used, the value for this
2694 directive is taken from the default (first-listed) virtual host best
2695 matching the current IP address and port combination.</p>
2699 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2700 <div class="directive-section"><h2><a name="LimitRequestLine" id="LimitRequestLine">LimitRequestLine</a> <a name="limitrequestline" id="limitrequestline">Directive</a></h2>
2701 <table class="directive">
2702 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limit the size of the HTTP request line that will be accepted
2703 from the client</td></tr>
2704 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestLine <var>bytes</var></code></td></tr>
2705 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestLine 8190</code></td></tr>
2706 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2707 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2708 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2710 <p>This directive sets the number of <var>bytes</var> that will be
2711 allowed on the HTTP request-line.</p>
2713 <p>The <code class="directive">LimitRequestLine</code> directive allows
2714 the server administrator to set the limit on the allowed size
2715 of a client's HTTP request-line. Since the request-line consists of the
2716 HTTP method, URI, and protocol version, the
2717 <code class="directive">LimitRequestLine</code> directive places a
2718 restriction on the length of a request-URI allowed for a request
2719 on the server. A server needs this value to be large enough to
2720 hold any of its resource names, including any information that
2721 might be passed in the query part of a <code>GET</code> request.</p>
2723 <p>This directive gives the server administrator greater
2724 control over abnormal client request behavior, which may be
2725 useful for avoiding some forms of denial-of-service attacks.</p>
2729 <pre class="prettyprint lang-config">LimitRequestLine 4094</pre>
2732 <div class="note">Under normal conditions, the value should not be changed from
2735 <div class="warning"><h3>Warning</h3>
2736 <p> When name-based virtual hosting is used, the value for this
2737 directive is taken from the default (first-listed) virtual host best
2738 matching the current IP address and port combination.</p>
2743 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2744 <div class="directive-section"><h2><a name="LimitXMLRequestBody" id="LimitXMLRequestBody">LimitXMLRequestBody</a> <a name="limitxmlrequestbody" id="limitxmlrequestbody">Directive</a></h2>
2745 <table class="directive">
2746 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of an XML-based request body</td></tr>
2747 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitXMLRequestBody <var>bytes</var></code></td></tr>
2748 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitXMLRequestBody 1000000</code></td></tr>
2749 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2750 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2751 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2752 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2754 <p>Limit (in bytes) on maximum size of an XML-based request
2755 body. A value of <code>0</code> will disable any checking.</p>
2759 <pre class="prettyprint lang-config">LimitXMLRequestBody 0</pre>
2764 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2765 <div class="directive-section"><h2><a name="Location" id="Location"><Location></a> <a name="location" id="location">Directive</a></h2>
2766 <table class="directive">
2767 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to matching
2769 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Location
2770 <var>URL-path</var>|<var>URL</var>> ... </Location></code></td></tr>
2771 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2772 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2773 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2775 <p>The <code class="directive"><Location></code> directive
2776 limits the scope of the enclosed directives by URL. It is similar to the
2777 <code class="directive"><a href="#directory"><Directory></a></code>
2778 directive, and starts a subsection which is terminated with a
2779 <code></Location></code> directive. <code class="directive"><Location></code> sections are processed in the
2780 order they appear in the configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
2781 <code>.htaccess</code> files are read, and after the <code class="directive"><a href="#files"><Files></a></code> sections.</p>
2783 <p><code class="directive"><Location></code> sections operate
2784 completely outside the filesystem. This has several consequences.
2785 Most importantly, <code class="directive"><Location></code>
2786 directives should not be used to control access to filesystem
2787 locations. Since several different URLs may map to the same
2788 filesystem location, such access controls may by circumvented.</p>
2790 <p>The enclosed directives will be applied to the request if the path component
2791 of the URL meets <em>any</em> of the following criteria:
2794 <li>The specified location matches exactly the path component of the URL.
2796 <li>The specified location, which ends in a forward slash, is a prefix
2797 of the path component of the URL (treated as a context root).
2799 <li>The specified location, with the addition of a trailing slash, is a
2800 prefix of the path component of the URL (also treated as a context root).
2804 In the example below, where no trailing slash is used, requests to
2805 /private1, /private1/ and /private1/file.txt will have the enclosed
2806 directives applied, but /private1other would not.
2808 <pre class="prettyprint lang-config"><Location "/private1">
2810 </Location></pre>
2813 In the example below, where a trailing slash is used, requests to
2814 /private2/ and /private2/file.txt will have the enclosed
2815 directives applied, but /private2 and /private2other would not.
2817 <pre class="prettyprint lang-config"><Location "/private2<em>/</em>">
2819 </Location></pre>
2822 <div class="note"><h3>When to use <code class="directive"><Location></code></h3>
2824 <p>Use <code class="directive"><Location></code> to apply
2825 directives to content that lives outside the filesystem. For
2826 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
2827 <code><Location "/"></code>, which is an easy way to
2828 apply a configuration to the entire server.</p>
2831 <p>For all origin (non-proxy) requests, the URL to be matched is a
2832 URL-path of the form <code>/path/</code>. <em>No scheme, hostname,
2833 port, or query string may be included.</em> For proxy requests, the
2834 URL to be matched is of the form
2835 <code>scheme://servername/path</code>, and you must include the
2838 <p>The URL may use wildcards. In a wild-card string, <code>?</code> matches
2839 any single character, and <code>*</code> matches any sequences of
2840 characters. Neither wildcard character matches a / in the URL-path.</p>
2842 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
2843 can also be used, with the addition of the <code>~</code>
2844 character. For example:</p>
2846 <pre class="prettyprint lang-config"><Location ~ "/(extra|special)/data">
2848 </Location></pre>
2851 <p>would match URLs that contained the substring <code>/extra/data</code>
2852 or <code>/special/data</code>. The directive <code class="directive"><a href="#locationmatch"><LocationMatch></a></code> behaves
2853 identical to the regex version of <code class="directive"><Location></code>, and is preferred, for the
2854 simple reason that <code>~</code> is hard to distinguish from
2855 <code>-</code> in many fonts.</p>
2857 <p>The <code class="directive"><Location></code>
2858 functionality is especially useful when combined with the
2859 <code class="directive"><a href="#sethandler">SetHandler</a></code>
2860 directive. For example, to enable status requests but allow them
2861 only from browsers at <code>example.com</code>, you might use:</p>
2863 <pre class="prettyprint lang-config"><Location "/status">
2864 SetHandler server-status
2865 Require host example.com
2866 </Location></pre>
2869 <div class="note"><h3>Note about / (slash)</h3>
2870 <p>The slash character has special meaning depending on where in a
2871 URL it appears. People may be used to its behavior in the filesystem
2872 where multiple adjacent slashes are frequently collapsed to a single
2873 slash (<em>i.e.</em>, <code>/home///foo</code> is the same as
2874 <code>/home/foo</code>). In URL-space this is not necessarily true.
2875 The <code class="directive"><a href="#locationmatch"><LocationMatch></a></code>
2876 directive and the regex version of <code class="directive"><Location></code> require you to explicitly specify multiple
2877 slashes if that is your intention.</p>
2879 <p>For example, <code><LocationMatch "^/abc"></code> would match
2880 the request URL <code>/abc</code> but not the request URL <code>
2881 //abc</code>. The (non-regex) <code class="directive"><Location></code> directive behaves similarly when used for
2882 proxy requests. But when (non-regex) <code class="directive"><Location></code> is used for non-proxy requests it will
2883 implicitly match multiple slashes with a single slash. For example,
2884 if you specify <code><Location "/abc/def"></code> and the
2885 request is to <code>/abc//def</code> then it will match.</p>
2890 <li><a href="../sections.html">How <Directory>, <Location>
2891 and <Files> sections work</a> for an explanation of how these
2892 different sections are combined when a request is received.</li>
2893 <li><code class="directive"><a href="#locationmatch">LocationMatch</a></code></li>
2896 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2897 <div class="directive-section"><h2><a name="LocationMatch" id="LocationMatch"><LocationMatch></a> <a name="locationmatch" id="locationmatch">Directive</a></h2>
2898 <table class="directive">
2899 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to regular-expression
2900 matching URLs</td></tr>
2901 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LocationMatch
2902 <var>regex</var>> ... </LocationMatch></code></td></tr>
2903 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2904 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2905 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2907 <p>The <code class="directive"><LocationMatch></code> directive
2908 limits the scope of the enclosed directives by URL, in an identical manner
2909 to <code class="directive"><a href="#location"><Location></a></code>. However,
2910 it takes a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>
2911 as an argument instead of a simple string. For example:</p>
2913 <pre class="prettyprint lang-config"><LocationMatch "/(extra|special)/data">
2915 </LocationMatch></pre>
2918 <p>would match URLs that contained the substring <code>/extra/data</code>
2919 or <code>/special/data</code>.</p>
2921 <div class="note"><p>If the intent is that a URL <strong>starts with</strong>
2922 <code>/extra/data</code>, rather than merely
2923 <strong>contains</strong> <code>/extra/data</code>, prefix the
2924 regular expression with a <code>^</code> to require this.</p>
2926 <pre class="prettyprint lang-config"><LocationMatch "^/(extra|special)/data"></pre>
2930 <p>From 2.4.8 onwards, named groups and backreferences are captured and
2931 written to the environment with the corresponding name prefixed with
2932 "MATCH_" and in upper case. This allows elements of URLs to be referenced
2933 from within <a href="../expr.html">expressions</a> and modules like
2934 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
2935 (unnamed) backreferences are ignored. Use named groups instead.</p>
2937 <pre class="prettyprint lang-config"><LocationMatch "^/combined/(?<sitename>[^/]+)">
2938 require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
2939 </LocationMatch></pre>
2944 <li><a href="../sections.html">How <Directory>, <Location>
2945 and <Files> sections work</a> for an explanation of how these
2946 different sections are combined when a request is received</li>
2949 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2950 <div class="directive-section"><h2><a name="LogLevel" id="LogLevel">LogLevel</a> <a name="loglevel" id="loglevel">Directive</a></h2>
2951 <table class="directive">
2952 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls the verbosity of the ErrorLog</td></tr>
2953 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel [<var>module</var>:]<var>level</var>
2954 [<var>module</var>:<var>level</var>] ...
2956 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LogLevel warn</code></td></tr>
2957 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2958 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2959 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2960 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Per-module and per-directory configuration is available in
2961 Apache HTTP Server 2.3.6 and later</td></tr>
2963 <p><code class="directive">LogLevel</code> adjusts the verbosity of the
2964 messages recorded in the error logs (see <code class="directive"><a href="#errorlog">ErrorLog</a></code> directive). The following
2965 <var>level</var>s are available, in order of decreasing
2968 <table class="bordered">
2971 <th><strong>Level</strong> </th>
2973 <th><strong>Description</strong> </th>
2975 <th><strong>Example</strong> </th>
2979 <td><code>emerg</code> </td>
2981 <td>Emergencies - system is unusable.</td>
2983 <td>"Child cannot open lock file. Exiting"</td>
2987 <td><code>alert</code> </td>
2989 <td>Action must be taken immediately.</td>
2991 <td>"getpwuid: couldn't determine user name from uid"</td>
2995 <td><code>crit</code> </td>
2997 <td>Critical Conditions.</td>
2999 <td>"socket: Failed to get a socket, exiting child"</td>
3003 <td><code>error</code> </td>
3005 <td>Error conditions.</td>
3007 <td>"Premature end of script headers"</td>
3011 <td><code>warn</code> </td>
3013 <td>Warning conditions.</td>
3015 <td>"child process 1234 did not exit, sending another
3020 <td><code>notice</code> </td>
3022 <td>Normal but significant condition.</td>
3024 <td>"httpd: caught SIGBUS, attempting to dump core in
3029 <td><code>info</code> </td>
3031 <td>Informational.</td>
3033 <td>"Server seems busy, (you may need to increase
3034 StartServers, or Min/MaxSpareServers)..."</td>
3038 <td><code>debug</code> </td>
3040 <td>Debug-level messages</td>
3042 <td>"Opening config file ..."</td>
3045 <td><code>trace1</code> </td>
3047 <td>Trace messages</td>
3049 <td>"proxy: FTP: control connection complete"</td>
3052 <td><code>trace2</code> </td>
3054 <td>Trace messages</td>
3056 <td>"proxy: CONNECT: sending the CONNECT request to the remote proxy"</td>
3059 <td><code>trace3</code> </td>
3061 <td>Trace messages</td>
3063 <td>"openssl: Handshake: start"</td>
3066 <td><code>trace4</code> </td>
3068 <td>Trace messages</td>
3070 <td>"read from buffered SSL brigade, mode 0, 17 bytes"</td>
3073 <td><code>trace5</code> </td>
3075 <td>Trace messages</td>
3077 <td>"map lookup FAILED: map=rewritemap key=keyname"</td>
3080 <td><code>trace6</code> </td>
3082 <td>Trace messages</td>
3084 <td>"cache lookup FAILED, forcing new map lookup"</td>
3087 <td><code>trace7</code> </td>
3089 <td>Trace messages, dumping large amounts of data</td>
3091 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3094 <td><code>trace8</code> </td>
3096 <td>Trace messages, dumping large amounts of data</td>
3098 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3102 <p>When a particular level is specified, messages from all
3103 other levels of higher significance will be reported as well.
3104 <em>E.g.</em>, when <code>LogLevel info</code> is specified,
3105 then messages with log levels of <code>notice</code> and
3106 <code>warn</code> will also be posted.</p>
3108 <p>Using a level of at least <code>crit</code> is
3113 <pre class="prettyprint lang-config">LogLevel notice</pre>
3116 <div class="note"><h3>Note</h3>
3117 <p>When logging to a regular file, messages of the level
3118 <code>notice</code> cannot be suppressed and thus are always
3119 logged. However, this doesn't apply when logging is done
3120 using <code>syslog</code>.</p>
3123 <p>Specifying a level without a module name will reset the level
3124 for all modules to that level. Specifying a level with a module
3125 name will set the level for that module only. It is possible to
3126 use the module source file name, the module identifier, or the
3127 module identifier with the trailing <code>_module</code> omitted
3128 as module specification. This means the following three specifications
3131 <pre class="prettyprint lang-config">LogLevel info ssl:warn
3132 LogLevel info mod_ssl.c:warn
3133 LogLevel info ssl_module:warn</pre>
3136 <p>It is also possible to change the level per directory:</p>
3138 <pre class="prettyprint lang-config">LogLevel info
3139 <Directory "/usr/local/apache/htdocs/app">
3141 </Directory></pre>
3145 Per directory loglevel configuration only affects messages that are
3146 logged after the request has been parsed and that are associated with
3147 the request. Log messages which are associated with the server or
3148 the connection are not affected. The latter can be influenced by the
3149 <code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code> directive,
3155 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
3156 <li><code class="directive"><a href="#errorlogformat">ErrorLogFormat</a></code></li>
3157 <li><code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code></li>
3158 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
3161 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3162 <div class="directive-section"><h2><a name="LogLevelOverride" id="LogLevelOverride">LogLevelOverride</a> <a name="logleveloverride" id="logleveloverride">Directive</a></h2>
3163 <table class="directive">
3164 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Override the verbosity of the ErrorLog for certain clients</td></tr>
3165 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel <var>ipaddress</var>[/<var>prefixlen</var>]
3166 [<var>module</var>:]<var>level</var> [<var>module</var>:<var>level</var>] ...
3168 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>unset</code></td></tr>
3169 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3170 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3171 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3172 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.5.0 and later</td></tr>
3174 <p><code class="directive">LogLevelOverride</code> adjusts the
3175 <code class="directive"><a href="#loglevel">LogLevel</a></code> for requests coming from
3176 certain client IP addresses.
3177 This allows to enable verbose logging only for certain test clients.
3178 The IP address is checked at a very early state in the connection
3179 processing. Therefore, <code class="directive">LogLevelOverride</code> allows to
3180 change the log level for things like the SSL handshake which happen before
3181 a <code class="directive"><a href="#loglevel">LogLevel</a></code> directive in an
3182 <code class="directive"><a href="#if"><If></a></code> container would
3185 <p><code class="directive">LogLevelOverride</code> accepts either a single
3186 IP-address or a CIDR IP-address/len subnet specification.
3187 For the syntax of the loglevel specification, see the
3188 <code class="directive"><a href="#loglevel">LogLevel</a></code> directive.</p>
3190 <p>For requests that match a <code class="directive">LogLevelOverride</code>
3191 directive, per-directory specifications of
3192 <code class="directive"><a href="#loglevel">LogLevel</a></code> are ignored.</p>
3196 <pre class="prettyprint lang-config"> LogLevelOverride 192.0.2.0/24 ssl:trace6
3197 LogLevelOverride 192.0.2.7 ssl:trace8</pre>
3201 <code class="directive">LogLevelOverride</code> only affects
3202 log messages that are associated with the request or the connection.
3203 Log messages which are associated with the server are not affected.
3209 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
3212 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3213 <div class="directive-section"><h2><a name="MaxKeepAliveRequests" id="MaxKeepAliveRequests">MaxKeepAliveRequests</a> <a name="maxkeepaliverequests" id="maxkeepaliverequests">Directive</a></h2>
3214 <table class="directive">
3215 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of requests allowed on a persistent
3216 connection</td></tr>
3217 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxKeepAliveRequests <var>number</var></code></td></tr>
3218 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxKeepAliveRequests 100</code></td></tr>
3219 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3220 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3221 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3223 <p>The <code class="directive">MaxKeepAliveRequests</code> directive
3224 limits the number of requests allowed per connection when
3225 <code class="directive"><a href="#keepalive">KeepAlive</a></code> is on. If it is
3226 set to <code>0</code>, unlimited requests will be allowed. We
3227 recommend that this setting be kept to a high value for maximum
3228 server performance.</p>
3232 <pre class="prettyprint lang-config">MaxKeepAliveRequests 500</pre>
3236 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3237 <div class="directive-section"><h2><a name="MaxRangeOverlaps" id="MaxRangeOverlaps">MaxRangeOverlaps</a> <a name="maxrangeoverlaps" id="maxrangeoverlaps">Directive</a></h2>
3238 <table class="directive">
3239 <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
3241 <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>
3242 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeOverlaps 20</code></td></tr>
3243 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3244 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3245 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3246 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3248 <p>The <code class="directive">MaxRangeOverlaps</code> directive
3249 limits the number of overlapping HTTP ranges the server is willing to
3250 return to the client. If more overlapping ranges than permitted are requested,
3251 the complete resource is returned instead.</p>
3254 <dt><strong>default</strong></dt>
3255 <dd>Limits the number of overlapping ranges to a compile-time default of 20.</dd>
3257 <dt><strong>none</strong></dt>
3258 <dd>No overlapping Range headers are allowed.</dd>
3260 <dt><strong>unlimited</strong></dt>
3261 <dd>The server does not limit the number of overlapping ranges it is
3262 willing to satisfy.</dd>
3264 <dt><var>number-of-ranges</var></dt>
3265 <dd>A positive number representing the maximum number of overlapping ranges the
3266 server is willing to satisfy.</dd>
3270 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3271 <div class="directive-section"><h2><a name="MaxRangeReversals" id="MaxRangeReversals">MaxRangeReversals</a> <a name="maxrangereversals" id="maxrangereversals">Directive</a></h2>
3272 <table class="directive">
3273 <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
3275 <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>
3276 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeReversals 20</code></td></tr>
3277 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3278 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3279 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3280 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3282 <p>The <code class="directive">MaxRangeReversals</code> directive
3283 limits the number of HTTP Range reversals the server is willing to
3284 return to the client. If more ranges reversals than permitted are requested,
3285 the complete resource is returned instead.</p>
3288 <dt><strong>default</strong></dt>
3289 <dd>Limits the number of range reversals to a compile-time default of 20.</dd>
3291 <dt><strong>none</strong></dt>
3292 <dd>No Range reversals headers are allowed.</dd>
3294 <dt><strong>unlimited</strong></dt>
3295 <dd>The server does not limit the number of range reversals it is
3296 willing to satisfy.</dd>
3298 <dt><var>number-of-ranges</var></dt>
3299 <dd>A positive number representing the maximum number of range reversals the
3300 server is willing to satisfy.</dd>
3304 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3305 <div class="directive-section"><h2><a name="MaxRanges" id="MaxRanges">MaxRanges</a> <a name="maxranges" id="maxranges">Directive</a></h2>
3306 <table class="directive">
3307 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of ranges allowed before returning the complete
3309 <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>
3310 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRanges 200</code></td></tr>
3311 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3312 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3313 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3314 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3316 <p>The <code class="directive">MaxRanges</code> directive
3317 limits the number of HTTP ranges the server is willing to
3318 return to the client. If more ranges than permitted are requested,
3319 the complete resource is returned instead.</p>
3322 <dt><strong>default</strong></dt>
3323 <dd>Limits the number of ranges to a compile-time default of 200.</dd>
3325 <dt><strong>none</strong></dt>
3326 <dd>Range headers are ignored.</dd>
3328 <dt><strong>unlimited</strong></dt>
3329 <dd>The server does not limit the number of ranges it is
3330 willing to satisfy.</dd>
3332 <dt><var>number-of-ranges</var></dt>
3333 <dd>A positive number representing the maximum number of ranges the
3334 server is willing to satisfy.</dd>
3338 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3339 <div class="directive-section"><h2><a name="MergeTrailers" id="MergeTrailers">MergeTrailers</a> <a name="mergetrailers" id="mergetrailers">Directive</a></h2>
3340 <table class="directive">
3341 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether trailers are merged into headers</td></tr>
3342 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MergeTrailers [on|off]</code></td></tr>
3343 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MergeTrailers off</code></td></tr>
3344 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3345 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3346 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3347 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.4.11 and later</td></tr>
3349 <p>This directive controls whether HTTP trailers are copied into the
3350 internal representation of HTTP headers. This merging occurs when the
3351 request body has been completely consumed, long after most header
3352 processing would have a chance to examine or modify request headers.</p>
3353 <p>This option is provided for compatibility with releases prior to 2.4.11,
3354 where trailers were always merged.</p>
3357 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3358 <div class="directive-section"><h2><a name="Mutex" id="Mutex">Mutex</a> <a name="mutex" id="mutex">Directive</a></h2>
3359 <table class="directive">
3360 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures mutex mechanism and lock file directory for all
3361 or specified mutexes</td></tr>
3362 <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>
3363 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Mutex default</code></td></tr>
3364 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3365 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3366 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3367 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.4 and later</td></tr>
3369 <p>The <code class="directive">Mutex</code> directive sets the mechanism,
3370 and optionally the lock file location, that httpd and modules use
3371 to serialize access to resources. Specify <code>default</code> as
3372 the second argument to change the settings for all mutexes; specify
3373 a mutex name (see table below) as the second argument to override
3374 defaults only for that mutex.</p>
3376 <p>The <code class="directive">Mutex</code> directive is typically used in
3377 the following exceptional situations:</p>
3380 <li>change the mutex mechanism when the default mechanism selected
3381 by <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> has a functional or performance
3384 <li>change the directory used by file-based mutexes when the
3385 default directory does not support locking</li>
3388 <div class="note"><h3>Supported modules</h3>
3389 <p>This directive only configures mutexes which have been registered
3390 with the core server using the <code>ap_mutex_register()</code> API.
3391 All modules bundled with httpd support the <code class="directive">Mutex</code>
3392 directive, but third-party modules may not. Consult the documentation
3393 of the third-party module, which must indicate the mutex name(s) which
3394 can be configured if this directive is supported.</p>
3397 <p>The following mutex <em>mechanisms</em> are available:</p>
3399 <li><code>default | yes</code>
3400 <p>This selects the default locking implementation, as determined by
3401 <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a>. The default locking implementation can
3402 be displayed by running <code class="program"><a href="../programs/httpd.html">httpd</a></code> with the
3403 <code>-V</code> option.</p></li>
3405 <li><code>none | no</code>
3406 <p>This effectively disables the mutex, and is only allowed for a
3407 mutex if the module indicates that it is a valid choice. Consult the
3408 module documentation for more information.</p></li>
3410 <li><code>posixsem</code>
3411 <p>This is a mutex variant based on a Posix semaphore.</p>
3413 <div class="warning"><h3>Warning</h3>
3414 <p>The semaphore ownership is not recovered if a thread in the process
3415 holding the mutex segfaults, resulting in a hang of the web server.</p>
3419 <li><code>sysvsem</code>
3420 <p>This is a mutex variant based on a SystemV IPC semaphore.</p>
3422 <div class="warning"><h3>Warning</h3>
3423 <p>It is possible to "leak" SysV semaphores if processes crash
3424 before the semaphore is removed.</p>
3427 <div class="warning"><h3>Security</h3>
3428 <p>The semaphore API allows for a denial of service attack by any
3429 CGIs running under the same uid as the webserver (<em>i.e.</em>,
3430 all CGIs, unless you use something like <code class="program"><a href="../programs/suexec.html">suexec</a></code>
3431 or <code>cgiwrapper</code>).</p>
3435 <li><code>sem</code>
3436 <p>This selects the "best" available semaphore implementation, choosing
3437 between Posix and SystemV IPC semaphores, in that order.</p></li>
3439 <li><code>pthread</code>
3440 <p>This is a mutex variant based on cross-process Posix thread
3443 <div class="warning"><h3>Warning</h3>
3444 <p>On most systems, if a child process terminates abnormally while
3445 holding a mutex that uses this implementation, the server will deadlock
3446 and stop responding to requests. When this occurs, the server will
3447 require a manual restart to recover.</p>
3448 <p>Solaris and Linux are notable exceptions as they provide a mechanism which
3449 usually allows the mutex to be recovered after a child process
3450 terminates abnormally while holding a mutex.</p>
3451 <p>If your system is POSIX compliant or if it implements the
3452 <code>pthread_mutexattr_setrobust_np()</code> function, you may be able
3453 to use the <code>pthread</code> option safely.</p>
3457 <li><code>fcntl:/path/to/mutex</code>
3458 <p>This is a mutex variant where a physical (lock-)file and the
3459 <code>fcntl()</code> function are used as the mutex.</p>
3461 <div class="warning"><h3>Warning</h3>
3462 <p>When multiple mutexes based on this mechanism are used within
3463 multi-threaded, multi-process environments, deadlock errors (EDEADLK)
3464 can be reported for valid mutex operations if <code>fcntl()</code>
3465 is not thread-aware, such as on Solaris.</p>
3469 <li><code>flock:/path/to/mutex</code>
3470 <p>This is similar to the <code>fcntl:/path/to/mutex</code> method
3471 with the exception that the <code>flock()</code> function is used to
3472 provide file locking.</p></li>
3474 <li><code>file:/path/to/mutex</code>
3475 <p>This selects the "best" available file locking implementation,
3476 choosing between <code>fcntl</code> and <code>flock</code>, in that
3480 <p>Most mechanisms are only available on selected platforms, where the
3481 underlying platform and <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> support it. Mechanisms
3482 which aren't available on all platforms are <em>posixsem</em>,
3483 <em>sysvsem</em>, <em>sem</em>, <em>pthread</em>, <em>fcntl</em>,
3484 <em>flock</em>, and <em>file</em>.</p>
3486 <p>With the file-based mechanisms <em>fcntl</em> and <em>flock</em>,
3487 the path, if provided, is a directory where the lock file will be created.
3488 The default directory is httpd's run-time file directory,
3489 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. If a relative
3490 path is provided, it is relative to
3491 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. Always use a local
3492 disk filesystem for <code>/path/to/mutex</code> and never a directory residing
3493 on a NFS- or AFS-filesystem. The basename of the file will be the mutex
3494 type, an optional instance string provided by the module, and unless the
3495 <code>OmitPID</code> keyword is specified, the process id of the httpd
3496 parent process will be appended to make the file name unique, avoiding
3497 conflicts when multiple httpd instances share a lock file directory. For
3498 example, if the mutex name is <code>mpm-accept</code> and the lock file
3499 directory is <code>/var/httpd/locks</code>, the lock file name for the
3500 httpd instance with parent process id 12345 would be
3501 <code>/var/httpd/locks/mpm-accept.12345</code>.</p>
3503 <div class="warning"><h3>Security</h3>
3504 <p>It is best to <em>avoid</em> putting mutex files in a world-writable
3505 directory such as <code>/var/tmp</code> because someone could create
3506 a denial of service attack and prevent the server from starting by
3507 creating a lockfile with the same name as the one the server will try
3511 <p>The following table documents the names of mutexes used by httpd
3512 and bundled modules.</p>
3514 <table class="bordered"><tr class="header">
3517 <th>Protected resource</th>
3520 <td><code>mpm-accept</code></td>
3521 <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>
3522 <td>incoming connections, to avoid the thundering herd problem;
3523 for more information, refer to the
3524 <a href="../misc/perf-tuning.html">performance tuning</a>
3528 <td><code>authdigest-client</code></td>
3529 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3530 <td>client list in shared memory</td>
3533 <td><code>authdigest-opaque</code></td>
3534 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3535 <td>counter in shared memory</td>
3538 <td><code>ldap-cache</code></td>
3539 <td><code class="module"><a href="../mod/mod_ldap.html">mod_ldap</a></code></td>
3540 <td>LDAP result cache</td>
3543 <td><code>rewrite-map</code></td>
3544 <td><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></td>
3545 <td>communication with external mapping programs, to avoid
3546 intermixed I/O from multiple requests</td>
3549 <td><code>ssl-cache</code></td>
3550 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3551 <td>SSL session cache</td>
3554 <td><code>ssl-stapling</code></td>
3555 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3556 <td>OCSP stapling response cache</td>
3559 <td><code>watchdog-callback</code></td>
3560 <td><code class="module"><a href="../mod/mod_watchdog.html">mod_watchdog</a></code></td>
3561 <td>callback function of a particular client module</td>
3565 <p>The <code>OmitPID</code> keyword suppresses the addition of the httpd
3566 parent process id from the lock file name.</p>
3568 <p>In the following example, the mutex mechanism for the MPM accept
3569 mutex will be changed from the compiled-in default to <code>fcntl</code>,
3570 with the associated lock file created in directory
3571 <code>/var/httpd/locks</code>. The mutex mechanism for all other mutexes
3572 will be changed from the compiled-in default to <code>sysvsem</code>.</p>
3574 <pre class="prettyprint lang-config">Mutex sysvsem default
3575 Mutex fcntl:/var/httpd/locks mpm-accept</pre>
3579 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3580 <div class="directive-section"><h2><a name="NameVirtualHost" id="NameVirtualHost">NameVirtualHost</a> <a name="namevirtualhost" id="namevirtualhost">Directive</a></h2>
3581 <table class="directive">
3582 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>DEPRECATED: Designates an IP address for name-virtual
3584 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NameVirtualHost <var>addr</var>[:<var>port</var>]</code></td></tr>
3585 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3586 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3587 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3590 <p>Prior to 2.3.11, <code class="directive">NameVirtualHost</code> was required
3591 to instruct the server that a particular IP address and port combination
3592 was usable as a name-based virtual host. In 2.3.11 and later,
3593 any time an IP address and port combination is used in multiple virtual
3594 hosts, name-based virtual hosting is automatically enabled for that address.</p>
3596 <p>This directive currently has no effect.</p>
3600 <li><a href="../vhosts/">Virtual Hosts
3601 documentation</a></li>
3604 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3605 <div class="directive-section"><h2><a name="Options" id="Options">Options</a> <a name="options" id="options">Directive</a></h2>
3606 <table class="directive">
3607 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures what features are available in a particular
3609 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Options
3610 [+|-]<var>option</var> [[+|-]<var>option</var>] ...</code></td></tr>
3611 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Options FollowSymlinks</code></td></tr>
3612 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3613 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
3614 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3615 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3616 <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>
3618 <p>The <code class="directive">Options</code> directive controls which
3619 server features are available in a particular directory.</p>
3621 <p><var>option</var> can be set to <code>None</code>, in which
3622 case none of the extra features are enabled, or one or more of
3626 <dt><code>All</code></dt>
3628 <dd>All options except for <code>MultiViews</code>.</dd>
3630 <dt><code>ExecCGI</code></dt>
3633 Execution of CGI scripts using <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>
3636 <dt><code>FollowSymLinks</code></dt>
3639 The server will follow symbolic links in this directory. This is
3640 the default setting.
3642 <p>Even though the server follows the symlink it does <em>not</em>
3643 change the pathname used to match against <code class="directive"><a href="#directory"><Directory></a></code> sections.</p>
3645 <p>The <code>FollowSymLinks</code> and
3646 <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
3647 <code>.htaccess</code> files.</p>
3649 <p>Omitting this option should not be considered a security restriction,
3650 since symlink testing is subject to race conditions that make it
3654 <dt><code>Includes</code></dt>
3657 Server-side includes provided by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
3660 <dt><code>IncludesNOEXEC</code></dt>
3664 Server-side includes are permitted, but the <code>#exec
3665 cmd</code> and <code>#exec cgi</code> are disabled. It is still
3666 possible to <code>#include virtual</code> CGI scripts from
3667 <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>ed
3670 <dt><code>Indexes</code></dt>
3673 If a URL which maps to a directory is requested and there
3674 is no <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
3675 (<em>e.g.</em>, <code>index.html</code>) in that directory, then
3676 <code class="module"><a href="../mod/mod_autoindex.html">mod_autoindex</a></code> will return a formatted listing
3677 of the directory.</dd>
3679 <dt><code>MultiViews</code></dt>
3682 <a href="../content-negotiation.html">Content negotiated</a>
3683 "MultiViews" are allowed using
3684 <code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code>.
3685 <div class="note"><h3>Note</h3> <p>This option gets ignored if set
3686 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>
3687 needs real resources to compare against and evaluate from.</p></div>
3690 <dt><code>SymLinksIfOwnerMatch</code></dt>
3692 <dd>The server will only follow symbolic links for which the
3693 target file or directory is owned by the same user id as the
3696 <div class="note"><h3>Note</h3>
3697 <p>The <code>FollowSymLinks</code> and
3698 <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
3699 <code>.htaccess</code> files.</p>
3701 <p>This option should not be considered a security restriction,
3702 since symlink testing is subject to race conditions that make it
3707 <p>Normally, if multiple <code class="directive">Options</code> could
3708 apply to a directory, then the most specific one is used and
3709 others are ignored; the options are not merged. (See <a href="../sections.html#merging">how sections are merged</a>.)
3710 However if <em>all</em> the options on the
3711 <code class="directive">Options</code> directive are preceded by a
3712 <code>+</code> or <code>-</code> symbol, the options are
3713 merged. Any options preceded by a <code>+</code> are added to the
3714 options currently in force, and any options preceded by a
3715 <code>-</code> are removed from the options currently in
3718 <div class="note"><h3>Note</h3>
3719 <p>Mixing <code class="directive">Options</code> with a <code>+</code> or
3720 <code>-</code> with those without is not valid syntax and will be
3721 rejected during server startup by the syntax check with an abort.</p>
3724 <p>For example, without any <code>+</code> and <code>-</code> symbols:</p>
3726 <pre class="prettyprint lang-config"><Directory "/web/docs">
3727 Options Indexes FollowSymLinks
3730 <Directory "/web/docs/spec">
3732 </Directory></pre>
3735 <p>then only <code>Includes</code> will be set for the
3736 <code>/web/docs/spec</code> directory. However if the second
3737 <code class="directive">Options</code> directive uses the <code>+</code> and
3738 <code>-</code> symbols:</p>
3740 <pre class="prettyprint lang-config"><Directory "/web/docs">
3741 Options Indexes FollowSymLinks
3744 <Directory "/web/docs/spec">
3745 Options +Includes -Indexes
3746 </Directory></pre>
3749 <p>then the options <code>FollowSymLinks</code> and
3750 <code>Includes</code> are set for the <code>/web/docs/spec</code>
3753 <div class="note"><h3>Note</h3>
3754 <p>Using <code>-IncludesNOEXEC</code> or
3755 <code>-Includes</code> disables server-side includes completely
3756 regardless of the previous setting.</p>
3759 <p>The default in the absence of any other settings is
3760 <code>FollowSymlinks</code>.</p>
3763 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3764 <div class="directive-section"><h2><a name="Protocol" id="Protocol">Protocol</a> <a name="protocol" id="protocol">Directive</a></h2>
3765 <table class="directive">
3766 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocol for a listening socket</td></tr>
3767 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocol <var>protocol</var></code></td></tr>
3768 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3769 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3770 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3771 <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>
3773 <p>This directive specifies the protocol used for a specific listening socket.
3774 The protocol is used to determine which module should handle a request and
3775 to apply protocol specific optimizations with the <code class="directive">AcceptFilter</code>
3778 <p>You only need to set the protocol if you are running on non-standard ports;
3779 otherwise, <code>http</code> is assumed for port 80 and <code>https</code>
3782 <p>For example, if you are running <code>https</code> on a non-standard port,
3783 specify the protocol explicitly:</p>
3785 <pre class="prettyprint lang-config">Protocol https</pre>
3788 <p>You can also specify the protocol using the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code> directive.</p>
3792 <li><code class="directive"><a href="#acceptfilter">AcceptFilter</a></code></li>
3793 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
3796 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3797 <div class="directive-section"><h2><a name="Protocols" id="Protocols">Protocols</a> <a name="protocols" id="protocols">Directive</a></h2>
3798 <table class="directive">
3799 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocols available for a server/virtual host</td></tr>
3800 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocols <var>protocol</var> ...</code></td></tr>
3801 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Protocols http/1.1</code></td></tr>
3802 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3803 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3804 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3805 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3807 <p>This directive specifies the list of protocols supported for a
3808 server/virtual host. The list determines the allowed protocols
3809 a client may negotiate for this server/host.</p>
3811 <p>You need to set protocols if you want to extend the available
3812 protocols for a server/host. By default, only the http/1.1 protocol
3813 (which includes the compatibility with 1.0 and 0.9 clients) is
3816 <p>For example, if you want to support HTTP/2 for a server with TLS,
3819 <pre class="prettyprint lang-config">Protocols h2 http/1.1</pre>
3822 <p>Valid protocols are <code>http/1.1</code> for http and https connections,
3823 <code>h2</code> on https connections and <code>h2c</code> for http
3824 connections. Modules may enable more protocols.</p>
3826 <p>It is safe to specify protocols that are unavailable/disabled. Such
3827 protocol names will simply be ignored.</p>
3829 <p>Protocols specified in base servers are inherited for virtual hosts
3830 only if the virtual host has no own Protocols directive. Or, the other
3831 way around, Protocols directives in virtual hosts replace any
3832 such directive in the base server.
3838 <li><code class="directive"><a href="#protocolshonororder">ProtocolsHonorOrder</a></code></li>
3841 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3842 <div class="directive-section"><h2><a name="ProtocolsHonorOrder" id="ProtocolsHonorOrder">ProtocolsHonorOrder</a> <a name="protocolshonororder" id="protocolshonororder">Directive</a></h2>
3843 <table class="directive">
3844 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines if order of Protocols determines precedence during negotiation</td></tr>
3845 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProtocolsHonorOrder On|Off</code></td></tr>
3846 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProtocolsHonorOrder On</code></td></tr>
3847 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3848 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3849 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3850 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3852 <p>This directive specifies if the server should honor the order in which
3853 the <code class="directive">Protocols</code> directive lists protocols.</p>
3855 <p>If configured Off, the client supplied list order of protocols has
3856 precedence over the order in the server configuration.</p>
3858 <p>With <code class="directive">ProtocolsHonorOrder</code> set to <code>on</code>
3859 (default), the client ordering does not matter and only the ordering
3860 in the server settings influences the outcome of the protocol
3866 <li><code class="directive"><a href="#protocols">Protocols</a></code></li>
3869 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3870 <div class="directive-section"><h2><a name="QualifyRedirectURL" id="QualifyRedirectURL">QualifyRedirectURL</a> <a name="qualifyredirecturl" id="qualifyredirecturl">Directive</a></h2>
3871 <table class="directive">
3872 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls whether the REDIRECT_URL environment variable is
3873 fully qualified</td></tr>
3874 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>QualifyRedirectURL ON|OFF</code></td></tr>
3875 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>QualifyRedirectURL OFF</code></td></tr>
3876 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3877 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3878 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3879 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3880 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directive supported in 2.4.18 and later. 2.4.17 acted
3881 as if 'QualifyRedirectURL ON' was configured.</td></tr>
3883 <p>This directive controls whether the server will ensure that the
3884 REDIRECT_URL environment variable is fully qualified. By default,
3885 the variable contains the verbatim URL requested by the client,
3886 such as "/index.html". With <code class="directive"><a href="#qualifyredirecturl on">QualifyRedirectURL ON</a></code>, the same request would result in a
3887 value such as "http://www.example.com/index.html".</p>
3888 <p>Even without this directive set, when a request is issued against a
3889 fully qualified URL, REDIRECT_URL will remain fully qualified.
3893 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3894 <div class="directive-section"><h2><a name="RegisterHttpMethod" id="RegisterHttpMethod">RegisterHttpMethod</a> <a name="registerhttpmethod" id="registerhttpmethod">Directive</a></h2>
3895 <table class="directive">
3896 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Register non-standard HTTP methods</td></tr>
3897 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RegisterHttpMethod <var>method</var> [<var>method</var> [...]]</code></td></tr>
3898 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3899 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3900 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3902 <p>HTTP Methods that are not conforming to the relvant RFCs are normally
3903 rejected by request processing in Apache HTTPD. To avoid this, modules
3904 can register non-standard HTTP methods they support.
3905 The <code class="directive">RegisterHttpMethod</code> allows to register such
3906 methods manually. This can be useful if such methods are forwarded
3907 for external processing, e.g. to a CGI script.</p>
3910 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3911 <div class="directive-section"><h2><a name="RLimitCPU" id="RLimitCPU">RLimitCPU</a> <a name="rlimitcpu" id="rlimitcpu">Directive</a></h2>
3912 <table class="directive">
3913 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the CPU consumption of processes launched
3914 by Apache httpd children</td></tr>
3915 <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>
3916 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3917 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3918 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3919 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3920 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3922 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3923 resource limit for all processes and the second parameter sets
3924 the maximum resource limit. Either parameter can be a number,
3925 or <code>max</code> to indicate to the server that the limit should
3926 be set to the maximum allowed by the operating system
3927 configuration. Raising the maximum resource limit requires that
3928 the server is running as <code>root</code> or in the initial startup
3931 <p>This applies to processes forked from Apache httpd children
3932 servicing requests, not the Apache httpd children themselves. This
3933 includes CGI scripts and SSI exec commands, but not any
3934 processes forked from the Apache httpd parent, such as piped
3937 <p>CPU resource limits are expressed in seconds per
3942 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
3943 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3946 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3947 <div class="directive-section"><h2><a name="RLimitMEM" id="RLimitMEM">RLimitMEM</a> <a name="rlimitmem" id="rlimitmem">Directive</a></h2>
3948 <table class="directive">
3949 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the memory consumption of processes launched
3950 by Apache httpd children</td></tr>
3951 <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>
3952 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3953 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3954 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3955 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3956 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3958 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3959 resource limit for all processes and the second parameter sets
3960 the maximum resource limit. Either parameter can be a number,
3961 or <code>max</code> to indicate to the server that the limit should
3962 be set to the maximum allowed by the operating system
3963 configuration. Raising the maximum resource limit requires that
3964 the server is running as <code>root</code> or in the initial startup
3967 <p>This applies to processes forked from Apache httpd children
3968 servicing requests, not the Apache httpd children themselves. This
3969 includes CGI scripts and SSI exec commands, but not any
3970 processes forked from the Apache httpd parent, such as piped
3973 <p>Memory resource limits are expressed in bytes per
3978 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
3979 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3982 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3983 <div class="directive-section"><h2><a name="RLimitNPROC" id="RLimitNPROC">RLimitNPROC</a> <a name="rlimitnproc" id="rlimitnproc">Directive</a></h2>
3984 <table class="directive">
3985 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of processes that can be launched by
3986 processes launched by Apache httpd children</td></tr>
3987 <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>
3988 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3989 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3990 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3991 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3992 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3994 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3995 resource limit for all processes, and the second parameter sets
3996 the maximum resource limit. Either parameter can be a number,
3997 or <code>max</code> to indicate to the server that the limit
3998 should be set to the maximum allowed by the operating system
3999 configuration. Raising the maximum resource limit requires that
4000 the server is running as <code>root</code> or in the initial startup
4003 <p>This applies to processes forked from Apache httpd children
4004 servicing requests, not the Apache httpd children themselves. This
4005 includes CGI scripts and SSI exec commands, but not any
4006 processes forked from the Apache httpd parent, such as piped
4009 <p>Process limits control the number of processes per user.</p>
4011 <div class="note"><h3>Note</h3>
4012 <p>If CGI processes are <strong>not</strong> running
4013 under user ids other than the web server user id, this directive
4014 will limit the number of processes that the server itself can
4015 create. Evidence of this situation will be indicated by
4016 <strong><code>cannot fork</code></strong> messages in the
4017 <code>error_log</code>.</p>
4022 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
4023 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
4026 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4027 <div class="directive-section"><h2><a name="ScriptInterpreterSource" id="ScriptInterpreterSource">ScriptInterpreterSource</a> <a name="scriptinterpretersource" id="scriptinterpretersource">Directive</a></h2>
4028 <table class="directive">
4029 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
4031 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ScriptInterpreterSource Registry|Registry-Strict|Script</code></td></tr>
4032 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ScriptInterpreterSource Script</code></td></tr>
4033 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4034 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4035 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4036 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4037 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Win32 only.</td></tr>
4039 <p>This directive is used to control how Apache httpd finds the
4040 interpreter used to run CGI scripts. The default setting is
4041 <code>Script</code>. This causes Apache httpd to use the interpreter pointed to
4042 by the shebang line (first line, starting with <code>#!</code>) in the
4043 script. On Win32 systems this line usually looks like:</p>
4045 <pre class="prettyprint lang-perl">#!C:/Perl/bin/perl.exe</pre>
4048 <p>or, if <code>perl</code> is in the <code>PATH</code>, simply:</p>
4050 <pre class="prettyprint lang-perl">#!perl</pre>
4053 <p>Setting <code>ScriptInterpreterSource Registry</code> will
4054 cause the Windows Registry tree <code>HKEY_CLASSES_ROOT</code> to be
4055 searched using the script file extension (e.g., <code>.pl</code>) as a
4056 search key. The command defined by the registry subkey
4057 <code>Shell\ExecCGI\Command</code> or, if it does not exist, by the subkey
4058 <code>Shell\Open\Command</code> is used to open the script file. If the
4059 registry keys cannot be found, Apache httpd falls back to the behavior of the
4060 <code>Script</code> option.</p>
4062 <div class="warning"><h3>Security</h3>
4063 <p>Be careful when using <code>ScriptInterpreterSource
4064 Registry</code> with <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories, because
4065 Apache httpd will try to execute <strong>every</strong> file within this
4066 directory. The <code>Registry</code> setting may cause undesired
4067 program calls on files which are typically not executed. For
4068 example, the default open command on <code>.htm</code> files on
4069 most Windows systems will execute Microsoft Internet Explorer, so
4070 any HTTP request for an <code>.htm</code> file existing within the
4071 script directory would start the browser in the background on the
4072 server. This is a good way to crash your system within a minute or
4076 <p>The option <code>Registry-Strict</code> which is new in Apache HTTP Server
4077 2.0 does the same thing as <code>Registry</code> but uses only the
4078 subkey <code>Shell\ExecCGI\Command</code>. The
4079 <code>ExecCGI</code> key is not a common one. It must be
4080 configured manually in the windows registry and hence prevents
4081 accidental program calls on your system.</p>
4084 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4085 <div class="directive-section"><h2><a name="SeeRequestTail" id="SeeRequestTail">SeeRequestTail</a> <a name="seerequesttail" id="seerequesttail">Directive</a></h2>
4086 <table class="directive">
4087 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine if mod_status displays the first 63 characters
4088 of a request or the last 63, assuming the request itself is greater than
4090 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SeeRequestTail On|Off</code></td></tr>
4091 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SeeRequestTail Off</code></td></tr>
4092 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4093 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4094 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4096 <p>mod_status with <code>ExtendedStatus On</code>
4097 displays the actual request being handled.
4098 For historical purposes, only 63 characters of the request
4099 are actually stored for display purposes. This directive
4100 controls whether the 1st 63 characters are stored (the previous
4101 behavior and the default) or if the last 63 characters are. This
4102 is only applicable, of course, if the length of the request is
4103 64 characters or greater.</p>
4105 <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:
4108 <table class="bordered">
4110 <th>Off (default)</th>
4111 <td>GET /disk1/storage/apache/htdocs/images/imagestore1/food/apples</td>
4115 <td>orage/apache/htdocs/images/imagestore1/food/apples.jpg HTTP/1.1</td>
4121 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4122 <div class="directive-section"><h2><a name="ServerAdmin" id="ServerAdmin">ServerAdmin</a> <a name="serveradmin" id="serveradmin">Directive</a></h2>
4123 <table class="directive">
4124 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Email address that the server includes in error
4125 messages sent to the client</td></tr>
4126 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAdmin <var>email-address</var>|<var>URL</var></code></td></tr>
4127 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4128 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4129 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4131 <p>The <code class="directive">ServerAdmin</code> sets the contact address
4132 that the server includes in any error messages it returns to the
4133 client. If the <code>httpd</code> doesn't recognize the supplied argument
4135 assumes, that it's an <var>email-address</var> and prepends it with
4136 <code>mailto:</code> in hyperlink targets. However, it's recommended to
4137 actually use an email address, since there are a lot of CGI scripts that
4138 make that assumption. If you want to use an URL, it should point to another
4139 server under your control. Otherwise users may not be able to contact you in
4142 <p>It may be worth setting up a dedicated address for this, e.g.</p>
4144 <pre class="prettyprint lang-config">ServerAdmin www-admin@foo.example.com</pre>
4146 <p>as users do not always mention that they are talking about the
4150 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4151 <div class="directive-section"><h2><a name="ServerAlias" id="ServerAlias">ServerAlias</a> <a name="serveralias" id="serveralias">Directive</a></h2>
4152 <table class="directive">
4153 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Alternate names for a host used when matching requests
4154 to name-virtual hosts</td></tr>
4155 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAlias <var>hostname</var> [<var>hostname</var>] ...</code></td></tr>
4156 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4157 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4158 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4160 <p>The <code class="directive">ServerAlias</code> directive sets the
4161 alternate names for a host, for use with <a href="../vhosts/name-based.html">name-based virtual hosts</a>. The
4162 <code class="directive">ServerAlias</code> may include wildcards, if appropriate.</p>
4164 <pre class="prettyprint lang-config"><VirtualHost *:80>
4165 ServerName server.example.com
4166 ServerAlias server server2.example.com server2
4167 ServerAlias *.example.com
4168 UseCanonicalName Off
4170 </VirtualHost></pre>
4173 <p>Name-based virtual hosts for the best-matching set of <code class="directive"><a href="#virtualhost"><virtualhost></a></code>s are processed
4174 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
4175 (nor for ServerName vs. ServerAlias). </p>
4177 <p>The complete list of names in the <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
4178 directive are treated just like a (non wildcard)
4179 <code class="directive">ServerAlias</code>.</p>
4184 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4185 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4188 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4189 <div class="directive-section"><h2><a name="ServerName" id="ServerName">ServerName</a> <a name="servername" id="servername">Directive</a></h2>
4190 <table class="directive">
4191 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Hostname and port that the server uses to identify
4193 <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>
4194 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4195 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4196 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4198 <p>The <code class="directive">ServerName</code> directive sets the
4199 request scheme, hostname and port that the server uses to identify itself.
4202 <p><code class="directive">ServerName</code> is used (possibly
4203 in conjunction with <code class="directive"><a href="#serveralias">ServerAlias</a></code>) to uniquely
4204 identify a virtual host, when using <a href="../vhosts/name-based.html">name-based virtual hosts</a>.</p>
4206 <p>Additionally, this is used when
4207 creating self-referential redirection URLs when
4208 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> is set to a non-default
4211 <p>For example, if the name of the
4212 machine hosting the web server is <code>simple.example.com</code>,
4213 but the machine also has the DNS alias <code>www.example.com</code>
4214 and you wish the web server to be so identified, the following
4215 directive should be used:</p>
4217 <pre class="prettyprint lang-config">ServerName www.example.com</pre>
4220 <p>The <code class="directive">ServerName</code> directive
4221 may appear anywhere within the definition of a server. However,
4222 each appearance overrides the previous appearance (within that
4225 <p>If no <code class="directive">ServerName</code> is specified, the
4226 server attempts to deduce the client visible hostname by first asking
4227 the operating system for the system hostname, and if that fails,
4228 performing a reverse lookup on an IP address present on the system.</p>
4230 <p>If no port is specified in the
4231 <code class="directive">ServerName</code>, then the server will use the
4232 port from the incoming request. For optimal reliability and
4233 predictability, you should specify an explicit hostname and port
4234 using the <code class="directive">ServerName</code> directive.</p>
4236 <p>If you are using <a href="../vhosts/name-based.html">name-based virtual hosts</a>,
4237 the <code class="directive">ServerName</code> inside a
4238 <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
4239 section specifies what hostname must appear in the request's
4240 <code>Host:</code> header to match this virtual host.</p>
4242 <p>Sometimes, the server runs behind a device that processes SSL,
4243 such as a reverse proxy, load balancer or SSL offload
4244 appliance. When this is the case, specify the
4245 <code>https://</code> scheme and the port number to which the
4246 clients connect in the <code class="directive">ServerName</code> directive
4247 to make sure that the server generates the correct
4248 self-referential URLs.
4251 <p>See the description of the
4252 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> and
4253 <code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code> directives for
4254 settings which determine whether self-referential URLs (e.g., by the
4255 <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> module) will refer to the
4256 specified port, or to the port number given in the client's request.
4259 <div class="warning">
4260 <p>Failure to set <code class="directive">ServerName</code> to a name that
4261 your server can resolve to an IP address will result in a startup
4262 warning. <code>httpd</code> will then use whatever hostname it can
4263 determine, using the system's <code>hostname</code> command. This
4264 will almost never be the hostname you actually want.</p>
4265 <div class="example"><p><code>
4266 httpd: Could not reliably determine the server's fully qualified domain name, using rocinante.local for ServerName
4273 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4274 Apache HTTP Server</a></li>
4275 <li><a href="../vhosts/">Apache HTTP Server virtual host
4276 documentation</a></li>
4277 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4278 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4279 <li><code class="directive"><a href="#serveralias">ServerAlias</a></code></li>
4282 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4283 <div class="directive-section"><h2><a name="ServerPath" id="ServerPath">ServerPath</a> <a name="serverpath" id="serverpath">Directive</a></h2>
4284 <table class="directive">
4285 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Legacy URL pathname for a name-based virtual host that
4286 is accessed by an incompatible browser</td></tr>
4287 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerPath <var>URL-path</var></code></td></tr>
4288 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4289 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4290 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4292 <p>The <code class="directive">ServerPath</code> directive sets the legacy
4293 URL pathname for a host, for use with <a href="../vhosts/">name-based virtual hosts</a>.</p>
4297 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4300 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4301 <div class="directive-section"><h2><a name="ServerRoot" id="ServerRoot">ServerRoot</a> <a name="serverroot" id="serverroot">Directive</a></h2>
4302 <table class="directive">
4303 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server installation</td></tr>
4304 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerRoot <var>directory-path</var></code></td></tr>
4305 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerRoot /usr/local/apache</code></td></tr>
4306 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4307 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4308 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4310 <p>The <code class="directive">ServerRoot</code> directive sets the
4311 directory in which the server lives. Typically it will contain the
4312 subdirectories <code>conf/</code> and <code>logs/</code>. Relative
4313 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
4314 relative to this directory.</p>
4316 <pre class="prettyprint lang-config">ServerRoot "/home/httpd"</pre>
4319 <p>The default location of <code class="directive">ServerRoot</code> may be
4320 modified by using the <code>--prefix</code> argument to
4321 <a href="../programs/configure.html"><code>configure</code></a>, and
4322 most third-party distributions of the server have a different
4323 default location from the one listed above.</p>
4328 <li><a href="../invoking.html">the <code>-d</code>
4329 option to <code>httpd</code></a></li>
4330 <li><a href="../misc/security_tips.html#serverroot">the
4331 security tips</a> for information on how to properly set
4332 permissions on the <code class="directive">ServerRoot</code></li>
4335 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4336 <div class="directive-section"><h2><a name="ServerSignature" id="ServerSignature">ServerSignature</a> <a name="serversignature" id="serversignature">Directive</a></h2>
4337 <table class="directive">
4338 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the footer on server-generated documents</td></tr>
4339 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerSignature On|Off|EMail</code></td></tr>
4340 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerSignature Off</code></td></tr>
4341 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4342 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
4343 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4344 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4346 <p>The <code class="directive">ServerSignature</code> directive allows the
4347 configuration of a trailing footer line under server-generated
4348 documents (error messages, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> ftp directory
4349 listings, <code class="module"><a href="../mod/mod_info.html">mod_info</a></code> output, ...). The reason why you
4350 would want to enable such a footer line is that in a chain of proxies,
4351 the user often has no possibility to tell which of the chained servers
4352 actually produced a returned error message.</p>
4354 <p>The <code>Off</code>
4355 setting, which is the default, suppresses the footer line (and is
4356 therefore compatible with the behavior of Apache-1.2 and
4357 below). The <code>On</code> setting simply adds a line with the
4358 server version number and <code class="directive"><a href="#servername">ServerName</a></code> of the serving virtual host,
4359 and the <code>EMail</code> setting additionally creates a
4360 "mailto:" reference to the <code class="directive"><a href="#serveradmin">ServerAdmin</a></code> of the referenced
4363 <p>After version 2.0.44, the details of the server version number
4364 presented are controlled by the <code class="directive"><a href="#servertokens">ServerTokens</a></code> directive.</p>
4368 <li><code class="directive"><a href="#servertokens">ServerTokens</a></code></li>
4371 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4372 <div class="directive-section"><h2><a name="ServerTokens" id="ServerTokens">ServerTokens</a> <a name="servertokens" id="servertokens">Directive</a></h2>
4373 <table class="directive">
4374 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the <code>Server</code> HTTP response
4376 <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>
4377 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerTokens Full</code></td></tr>
4378 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4379 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4380 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4382 <p>This directive controls whether <code>Server</code> response
4383 header field which is sent back to clients includes a
4384 description of the generic OS-type of the server as well as
4385 information about compiled-in modules.</p>
4388 <dt><code>ServerTokens Full</code> (or not specified)</dt>
4390 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4391 (Unix) PHP/4.2.2 MyMod/1.2</code></dd>
4393 <dt><code>ServerTokens Prod[uctOnly]</code></dt>
4395 <dd>Server sends (<em>e.g.</em>): <code>Server:
4398 <dt><code>ServerTokens Major</code></dt>
4400 <dd>Server sends (<em>e.g.</em>): <code>Server:
4401 Apache/2</code></dd>
4403 <dt><code>ServerTokens Minor</code></dt>
4405 <dd>Server sends (<em>e.g.</em>): <code>Server:
4406 Apache/2.4</code></dd>
4408 <dt><code>ServerTokens Min[imal]</code></dt>
4410 <dd>Server sends (<em>e.g.</em>): <code>Server:
4411 Apache/2.4.2</code></dd>
4413 <dt><code>ServerTokens OS</code></dt>
4415 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4420 <p>This setting applies to the entire server, and cannot be
4421 enabled or disabled on a virtualhost-by-virtualhost basis.</p>
4423 <p>After version 2.0.44, this directive also controls the
4424 information presented by the <code class="directive"><a href="#serversignature">ServerSignature</a></code> directive.</p>
4426 <div class="note">Setting <code class="directive">ServerTokens</code> to less than
4427 <code>minimal</code> is not recommended because it makes it more
4428 difficult to debug interoperational problems. Also note that
4429 disabling the Server: header does nothing at all to make your
4430 server more secure. The idea of "security through obscurity"
4431 is a myth and leads to a false sense of safety.</div>
4435 <li><code class="directive"><a href="#serversignature">ServerSignature</a></code></li>
4438 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4439 <div class="directive-section"><h2><a name="SetHandler" id="SetHandler">SetHandler</a> <a name="sethandler" id="sethandler">Directive</a></h2>
4440 <table class="directive">
4441 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be processed by a
4443 <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>
4444 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4445 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4446 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4447 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4448 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4450 <p>When placed into an <code>.htaccess</code> file or a
4451 <code class="directive"><a href="#directory"><Directory></a></code> or
4452 <code class="directive"><a href="#location"><Location></a></code>
4453 section, this directive forces all matching files to be parsed
4454 through the <a href="../handler.html">handler</a> given by
4455 <var>handler-name</var>. For example, if you had a directory you
4456 wanted to be parsed entirely as imagemap rule files, regardless
4457 of extension, you might put the following into an
4458 <code>.htaccess</code> file in that directory:</p>
4460 <pre class="prettyprint lang-config">SetHandler imap-file</pre>
4463 <p>Another example: if you wanted to have the server display a
4464 status report whenever a URL of
4465 <code>http://servername/status</code> was called, you might put
4466 the following into <code>httpd.conf</code>:</p>
4468 <pre class="prettyprint lang-config"><Location "/status">
4469 SetHandler server-status
4470 </Location></pre>
4473 <p>You could also use this directive to configure a particular
4474 handler for files with a particular file extension. For example:</p>
4476 <pre class="prettyprint lang-config"><FilesMatch "\.php$">
4477 SetHandler application/x-httpd-php
4478 </FilesMatch></pre>
4481 <p>String-valued expressions can be used to reference per-request
4482 variables, including backreferences to named regular expressions:</p>
4484 <pre class="prettyprint lang-config"><LocationMatch ^/app/(?<sub>[^/]+)/>
4485 SetHandler "proxy:unix:/var/run/app_%{env:MATCH_sub}.sock|fcgi://localhost:8080"
4486 </LocationMatch></pre>
4489 <p>You can override an earlier defined <code class="directive">SetHandler</code>
4490 directive by using the value <code>None</code>.</p>
4492 <div class="note"><h3>Note</h3>
4493 <p>Because <code class="directive">SetHandler</code> overrides default handlers,
4494 normal behavior such as handling of URLs ending in a slash (/) as
4495 directories or index files is suppressed.</p></div>
4499 <li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li>
4502 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4503 <div class="directive-section"><h2><a name="SetInputFilter" id="SetInputFilter">SetInputFilter</a> <a name="setinputfilter" id="setinputfilter">Directive</a></h2>
4504 <table class="directive">
4505 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process client requests and POST
4507 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetInputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4508 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4509 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4510 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4511 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4513 <p>The <code class="directive">SetInputFilter</code> directive sets the
4514 filter or filters which will process client requests and POST
4515 input when they are received by the server. This is in addition to
4516 any filters defined elsewhere, including the
4517 <code class="directive"><a href="../mod/mod_mime.html#addinputfilter">AddInputFilter</a></code>
4520 <p>If more than one filter is specified, they must be separated
4521 by semicolons in the order in which they should process the
4526 <li><a href="../filter.html">Filters</a> documentation</li>
4529 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4530 <div class="directive-section"><h2><a name="SetOutputFilter" id="SetOutputFilter">SetOutputFilter</a> <a name="setoutputfilter" id="setoutputfilter">Directive</a></h2>
4531 <table class="directive">
4532 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process responses from the
4534 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetOutputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4535 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4536 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4537 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4538 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4540 <p>The <code class="directive">SetOutputFilter</code> directive sets the filters
4541 which will process responses from the server before they are
4542 sent to the client. This is in addition to any filters defined
4543 elsewhere, including the
4544 <code class="directive"><a href="../mod/mod_mime.html#addoutputfilter">AddOutputFilter</a></code>
4547 <p>For example, the following configuration will process all files
4548 in the <code>/www/data/</code> directory for server-side
4551 <pre class="prettyprint lang-config"><Directory "/www/data/">
4552 SetOutputFilter INCLUDES
4553 </Directory></pre>
4556 <p>If more than one filter is specified, they must be separated
4557 by semicolons in the order in which they should process the
4562 <li><a href="../filter.html">Filters</a> documentation</li>
4565 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4566 <div class="directive-section"><h2><a name="TimeOut" id="TimeOut">TimeOut</a> <a name="timeout" id="timeout">Directive</a></h2>
4567 <table class="directive">
4568 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for
4569 certain events before failing a request</td></tr>
4570 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TimeOut <var>seconds</var></code></td></tr>
4571 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TimeOut 60</code></td></tr>
4572 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4573 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4574 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4576 <p>The <code class="directive">TimeOut</code> directive defines the length
4577 of time Apache httpd will wait for I/O in various circumstances:</p>
4580 <li><p>When reading data from the client, the length of time to
4581 wait for a TCP packet to arrive if the read buffer is
4583 <p> For initial data on a new connection, this directive doesn't
4584 take effect until after any configured <code class="directive"><a href="#acceptfilter">
4585 AcceptFilter</a></code> has passed the new connection to the server.</p>
4588 <li>When writing data to the client, the length of time to wait
4589 for an acknowledgement of a packet if the send buffer is
4592 <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>,
4593 the length of time to wait for output from a CGI script.</li>
4595 <li>In <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>, the length of time to
4596 wait for output from a filtering process.</li>
4598 <li>In <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, the default timeout value if
4599 <code class="directive"><a href="../mod/mod_proxy.html#proxytimeout">ProxyTimeout</a></code> is not
4605 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4606 <div class="directive-section"><h2><a name="TraceEnable" id="TraceEnable">TraceEnable</a> <a name="traceenable" id="traceenable">Directive</a></h2>
4607 <table class="directive">
4608 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines the behavior on <code>TRACE</code> requests</td></tr>
4609 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TraceEnable <var>[on|off|extended]</var></code></td></tr>
4610 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TraceEnable on</code></td></tr>
4611 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4612 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4613 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4615 <p>This directive overrides the behavior of <code>TRACE</code> for both
4616 the core server and <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. The default
4617 <code>TraceEnable on</code> permits <code>TRACE</code> requests per
4618 RFC 2616, which disallows any request body to accompany the request.
4619 <code>TraceEnable off</code> causes the core server and
4620 <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> to return a <code>405</code> (Method not
4621 allowed) error to the client.</p>
4623 <p>Finally, for testing and diagnostic purposes only, request
4624 bodies may be allowed using the non-compliant <code>TraceEnable
4625 extended</code> directive. The core (as an origin server) will
4626 restrict the request body to 64Kb (plus 8Kb for chunk headers if
4627 <code>Transfer-Encoding: chunked</code> is used). The core will
4628 reflect the full headers and all chunk headers with the response
4629 body. As a proxy server, the request body is not restricted to 64Kb.</p>
4631 <div class="note"><h3>Note</h3>
4633 <p>Despite claims to the contrary, enabling the <code>TRACE</code>
4634 method does not expose any security vulnerability in Apache httpd.
4635 The <code>TRACE</code> method is defined by the HTTP/1.1
4636 specification and implementations are expected to support it.</p>
4641 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4642 <div class="directive-section"><h2><a name="UnDefine" id="UnDefine">UnDefine</a> <a name="undefine" id="undefine">Directive</a></h2>
4643 <table class="directive">
4644 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Undefine the existence of a variable</td></tr>
4645 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UnDefine <var>parameter-name</var></code></td></tr>
4646 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4647 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4648 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4650 <p>Undoes the effect of a <code class="directive"><a href="#define">Define</a></code> or
4651 of passing a <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</p>
4652 <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
4653 <code>-D</code> arguments in any startup scripts.</p>
4654 <p>While this directive is supported in virtual host context,
4655 the changes it makes are visible to any later configuration
4656 directives, beyond any enclosing virtual host.</p>
4659 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4660 <div class="directive-section"><h2><a name="UseCanonicalName" id="UseCanonicalName">UseCanonicalName</a> <a name="usecanonicalname" id="usecanonicalname">Directive</a></h2>
4661 <table class="directive">
4662 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own name and
4664 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalName On|Off|DNS</code></td></tr>
4665 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalName Off</code></td></tr>
4666 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4667 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4668 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4670 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4671 URL -- that is, a URL that refers back to the same server. With
4672 <code>UseCanonicalName On</code> Apache httpd will use the hostname and port
4673 specified in the <code class="directive"><a href="#servername">ServerName</a></code>
4674 directive to construct the canonical name for the server. This name
4675 is used in all self-referential URLs, and for the values of
4676 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in CGIs.</p>
4678 <p>With <code>UseCanonicalName Off</code> Apache httpd will form
4679 self-referential URLs using the hostname and port supplied by
4680 the client if any are supplied (otherwise it will use the
4681 canonical name, as defined above). These values are the same
4682 that are used to implement <a href="../vhosts/name-based.html">name-based virtual hosts</a>
4683 and are available with the same clients. The CGI variables
4684 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
4685 constructed from the client supplied values as well.</p>
4687 <p>An example where this may be useful is on an intranet server
4688 where you have users connecting to the machine using short
4689 names such as <code>www</code>. You'll notice that if the users
4690 type a shortname and a URL which is a directory, such as
4691 <code>http://www/splat</code>, <em>without the trailing
4692 slash</em>, then Apache httpd will redirect them to
4693 <code>http://www.example.com/splat/</code>. If you have
4694 authentication enabled, this will cause the user to have to
4695 authenticate twice (once for <code>www</code> and once again
4696 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">
4697 the FAQ on this subject for more information</a>). But if
4698 <code class="directive">UseCanonicalName</code> is set <code>Off</code>, then
4699 Apache httpd will redirect to <code>http://www/splat/</code>.</p>
4701 <p>There is a third option, <code>UseCanonicalName DNS</code>,
4702 which is intended for use with mass IP-based virtual hosting to
4703 support ancient clients that do not provide a
4704 <code>Host:</code> header. With this option, Apache httpd does a
4705 reverse DNS lookup on the server IP address that the client
4706 connected to in order to work out self-referential URLs.</p>
4708 <div class="warning"><h3>Warning</h3>
4709 <p>If CGIs make assumptions about the values of <code>SERVER_NAME</code>,
4710 they may be broken by this option. The client is essentially free
4711 to give whatever value they want as a hostname. But if the CGI is
4712 only using <code>SERVER_NAME</code> to construct self-referential URLs,
4713 then it should be just fine.</p>
4718 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4719 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4720 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4723 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4724 <div class="directive-section"><h2><a name="UseCanonicalPhysicalPort" id="UseCanonicalPhysicalPort">UseCanonicalPhysicalPort</a> <a name="usecanonicalphysicalport" id="usecanonicalphysicalport">Directive</a></h2>
4725 <table class="directive">
4726 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own port</td></tr>
4727 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalPhysicalPort On|Off</code></td></tr>
4728 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalPhysicalPort Off</code></td></tr>
4729 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4730 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4731 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4733 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4734 URL -- that is, a URL that refers back to the same server. With
4735 <code>UseCanonicalPhysicalPort On</code>, Apache httpd will, when
4736 constructing the canonical port for the server to honor
4737 the <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> directive,
4738 provide the actual physical port number being used by this request
4739 as a potential port. With <code>UseCanonicalPhysicalPort Off</code>,
4740 Apache httpd will not ever use the actual physical port number, instead
4741 relying on all configured information to construct a valid port number.</p>
4743 <div class="note"><h3>Note</h3>
4744 <p>The ordering of the lookup when the physical port is used is as
4747 <dt><code>UseCanonicalName On</code></dt>
4750 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4751 <li>Physical port</li>
4752 <li>Default port</li>
4755 <dt><code>UseCanonicalName Off | DNS</code></dt>
4758 <li>Parsed port from <code>Host:</code> header</li>
4759 <li>Physical port</li>
4760 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4761 <li>Default port</li>
4766 <p>With <code>UseCanonicalPhysicalPort Off</code>, the
4767 physical ports are removed from the ordering.</p>
4773 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4774 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4775 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4778 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4779 <div class="directive-section"><h2><a name="VirtualHost" id="VirtualHost"><VirtualHost></a> <a name="virtualhost" id="virtualhost">Directive</a></h2>
4780 <table class="directive">
4781 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only to a specific
4782 hostname or IP address</td></tr>
4783 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><VirtualHost
4784 <var>addr</var>[:<var>port</var>] [<var>addr</var>[:<var>port</var>]]
4785 ...> ... </VirtualHost></code></td></tr>
4786 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4787 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4788 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4790 <p><code class="directive"><VirtualHost></code> and
4791 <code></VirtualHost></code> are used to enclose a group of
4792 directives that will apply only to a particular virtual host. Any
4793 directive that is allowed in a virtual host context may be
4794 used. When the server receives a request for a document on a
4795 particular virtual host, it uses the configuration directives
4796 enclosed in the <code class="directive"><VirtualHost></code>
4797 section. <var>Addr</var> can be any of the following, optionally followed by
4798 a colon and a port number (or *):</p>
4801 <li>The IP address of the virtual host;</li>
4803 <li>A fully qualified domain name for the IP address of the
4804 virtual host (not recommended);</li>
4806 <li>The character <code>*</code>, which acts as a wildcard and matches
4807 any IP address.</li>
4809 <li>The string <code>_default_</code>, which is an alias for <code>*</code></li>
4813 <pre class="prettyprint lang-config"><VirtualHost 10.1.2.3:80>
4814 ServerAdmin webmaster@host.example.com
4815 DocumentRoot "/www/docs/host.example.com"
4816 ServerName host.example.com
4817 ErrorLog "logs/host.example.com-error_log"
4818 TransferLog "logs/host.example.com-access_log"
4819 </VirtualHost></pre>
4823 <p>IPv6 addresses must be specified in square brackets because
4824 the optional port number could not be determined otherwise. An
4825 IPv6 example is shown below:</p>
4827 <pre class="prettyprint lang-config"><VirtualHost [2001:db8::a00:20ff:fea7:ccea]:80>
4828 ServerAdmin webmaster@host.example.com
4829 DocumentRoot "/www/docs/host.example.com"
4830 ServerName host.example.com
4831 ErrorLog "logs/host.example.com-error_log"
4832 TransferLog "logs/host.example.com-access_log"
4833 </VirtualHost></pre>
4836 <p>Each Virtual Host must correspond to a different IP address,
4837 different port number, or a different host name for the server,
4838 in the former case the server machine must be configured to
4839 accept IP packets for multiple addresses. (If the machine does
4840 not have multiple network interfaces, then this can be
4841 accomplished with the <code>ifconfig alias</code> command -- if
4842 your OS supports it).</p>
4844 <div class="note"><h3>Note</h3>
4845 <p>The use of <code class="directive"><VirtualHost></code> does
4846 <strong>not</strong> affect what addresses Apache httpd listens on. You
4847 may need to ensure that Apache httpd is listening on the correct addresses
4848 using <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>.</p>
4851 <p>A <code class="directive"><a href="#servername">ServerName</a></code> should be
4852 specified inside each <code class="directive"><VirtualHost></code> block. If it is absent, the
4853 <code class="directive"><a href="#servername">ServerName</a></code> from the "main"
4854 server configuration will be inherited.</p>
4856 <p>When a request is received, the server first maps it to the best matching
4857 <code class="directive"><VirtualHost></code> based on the local
4858 IP address and port combination only. Non-wildcards have a higher
4859 precedence. If no match based on IP and port occurs at all, the
4860 "main" server configuration is used.</p>
4862 <p>If multiple virtual hosts contain the best matching IP address and port,
4863 the server selects from these virtual hosts the best match based on the
4864 requested hostname. If no matching name-based virtual host is found,
4865 then the first listed virtual host that matched the IP address will be
4866 used. As a consequence, the first listed virtual host for a given IP address
4867 and port combination is the default virtual host for that IP and port
4870 <div class="warning"><h3>Security</h3>
4871 <p>See the <a href="../misc/security_tips.html">security tips</a>
4872 document for details on why your security could be compromised if the
4873 directory where log files are stored is writable by anyone other
4874 than the user that starts the server.</p>
4879 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4880 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4881 Apache HTTP Server</a></li>
4882 <li><a href="../bind.html">Setting
4883 which addresses and ports Apache HTTP Server uses</a></li>
4884 <li><a href="../sections.html">How <Directory>, <Location>
4885 and <Files> sections work</a> for an explanation of how these
4886 different sections are combined when a request is received</li>
4889 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4890 <div class="directive-section"><h2><a name="Warning" id="Warning">Warning</a> <a name="warning" id="warning">Directive</a></h2>
4891 <table class="directive">
4892 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Warn from configuration parsing with a custom message</td></tr>
4893 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Warning <var>message</var></code></td></tr>
4894 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4895 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4896 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4897 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4899 <p>If an issue can be detected from within the configuration, this
4900 directive can be used to generate a custom warning message. The
4901 configuration parsing is not halted. The typical use is to check
4902 whether some user define options are set, and warn if not.</p>
4904 <pre class="prettyprint lang-config"># Example
4905 # tell when ReverseProxy is not set
4906 <IfDefine !ReverseProxy>
4907 Warning "reverse proxy is not started, hope this is okay!"
4910 <IfDefine ReverseProxy>
4911 # define custom proxy configuration
4912 </IfDefine></pre>
4918 <div class="bottomlang">
4919 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
4920 <a href="../en/mod/core.html" title="English"> en </a> |
4921 <a href="../es/mod/core.html" hreflang="es" rel="alternate" title="Español"> es </a> |
4922 <a href="../fr/mod/core.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
4923 <a href="../ja/mod/core.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
4924 <a href="../tr/mod/core.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
4925 </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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