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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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34 <a href="../tr/mod/core.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
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 connect
192 AcceptFilter https connect</pre>
195 <p>Window's mpm_winnt interprets the AcceptFilter to toggle the AcceptEx()
196 API, and does not support http protocol buffering. <code>connect</code>
197 will use the AcceptEx() API, also retrieve the network endpoint
198 addresses, but like <code>none</code> the <code>connect</code> option
199 does not wait for the initial data transmission.</p>
201 <p>On Windows, <code>none</code> uses accept() rather than AcceptEx()
202 and will not recycle sockets between connections. This is useful for
203 network adapters with broken driver support, as well as some virtual
204 network providers such as vpn drivers, or spam, virus or spyware
207 <div class="warning">
208 <h3>The <code>data</code> AcceptFilter (Windows)</h3>
210 <p>For versions 2.4.23 and prior, the Windows <code>data</code> accept
211 filter waited until data had been transmitted and the initial data
212 buffer and network endpoint addresses had been retrieved from the
213 single AcceptEx() invocation. This implementation was subject to a
214 denial of service attack and has been disabled.</p>
216 <p>Current releases of httpd default to the <code>connect</code> filter
217 on Windows, and will fall back to <code>connect</code> if
218 <code>data</code> is specified. Users of prior releases are encouraged
219 to add an explicit setting of <code>connect</code> for their
220 AcceptFilter, as shown above.</p>
226 <li><code class="directive"><a href="#protocol">Protocol</a></code></li>
229 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
230 <div class="directive-section"><h2><a name="AcceptPathInfo" id="AcceptPathInfo">AcceptPathInfo</a> <a name="acceptpathinfo" id="acceptpathinfo">Directive</a></h2>
231 <table class="directive">
232 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Resources accept trailing pathname information</td></tr>
233 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptPathInfo On|Off|Default</code></td></tr>
234 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AcceptPathInfo Default</code></td></tr>
235 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
236 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
237 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
238 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
241 <p>This directive controls whether requests that contain trailing
242 pathname information that follows an actual filename (or
243 non-existent file in an existing directory) will be accepted or
244 rejected. The trailing pathname information can be made
245 available to scripts in the <code>PATH_INFO</code> environment
248 <p>For example, assume the location <code>/test/</code> points to
249 a directory that contains only the single file
250 <code>here.html</code>. Then requests for
251 <code>/test/here.html/more</code> and
252 <code>/test/nothere.html/more</code> both collect
253 <code>/more</code> as <code>PATH_INFO</code>.</p>
255 <p>The three possible arguments for the
256 <code class="directive">AcceptPathInfo</code> directive are:</p>
258 <dt><code>Off</code></dt><dd>A request will only be accepted if it
259 maps to a literal path that exists. Therefore a request with
260 trailing pathname information after the true filename such as
261 <code>/test/here.html/more</code> in the above example will return
262 a 404 NOT FOUND error.</dd>
264 <dt><code>On</code></dt><dd>A request will be accepted if a
265 leading path component maps to a file that exists. The above
266 example <code>/test/here.html/more</code> will be accepted if
267 <code>/test/here.html</code> maps to a valid file.</dd>
269 <dt><code>Default</code></dt><dd>The treatment of requests with
270 trailing pathname information is determined by the <a href="../handler.html">handler</a> responsible for the request.
271 The core handler for normal files defaults to rejecting
272 <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
273 <code>PATH_INFO</code> by default.</dd>
276 <p>The primary purpose of the <code>AcceptPathInfo</code>
277 directive is to allow you to override the handler's choice of
278 accepting or rejecting <code>PATH_INFO</code>. This override is required,
279 for example, when you use a <a href="../filter.html">filter</a>, such
280 as <a href="mod_include.html">INCLUDES</a>, to generate content
281 based on <code>PATH_INFO</code>. The core handler would usually reject
282 the request, so you can use the following configuration to enable
285 <pre class="prettyprint lang-config"><Files "mypaths.shtml">
287 SetOutputFilter INCLUDES
294 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
295 <div class="directive-section"><h2><a name="AccessFileName" id="AccessFileName">AccessFileName</a> <a name="accessfilename" id="accessfilename">Directive</a></h2>
296 <table class="directive">
297 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Name of the distributed configuration file</td></tr>
298 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AccessFileName <var>filename</var> [<var>filename</var>] ...</code></td></tr>
299 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AccessFileName .htaccess</code></td></tr>
300 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
301 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
302 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
304 <p>While processing a request, the server looks for
305 the first existing configuration file from this list of names in
306 every directory of the path to the document, if distributed
307 configuration files are <a href="#allowoverride">enabled for that
308 directory</a>. For example:</p>
310 <pre class="prettyprint lang-config">AccessFileName .acl</pre>
313 <p>Before returning the document
314 <code>/usr/local/web/index.html</code>, the server will read
315 <code>/.acl</code>, <code>/usr/.acl</code>,
316 <code>/usr/local/.acl</code> and <code>/usr/local/web/.acl</code>
317 for directives unless they have been disabled with:</p>
319 <pre class="prettyprint lang-config"><Directory "/">
321 </Directory></pre>
326 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
327 <li><a href="../configuring.html">Configuration Files</a></li>
328 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
331 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
332 <div class="directive-section"><h2><a name="AddDefaultCharset" id="AddDefaultCharset">AddDefaultCharset</a> <a name="adddefaultcharset" id="adddefaultcharset">Directive</a></h2>
333 <table class="directive">
334 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Default charset parameter to be added when a response
335 content-type is <code>text/plain</code> or <code>text/html</code></td></tr>
336 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AddDefaultCharset On|Off|<var>charset</var></code></td></tr>
337 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AddDefaultCharset Off</code></td></tr>
338 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
339 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
340 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
341 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
343 <p>This directive specifies a default value for the media type
344 charset parameter (the name of a character encoding) to be added
345 to a response if and only if the response's content-type is either
346 <code>text/plain</code> or <code>text/html</code>. This should override
347 any charset specified in the body of the response via a <code>META</code>
348 element, though the exact behavior is often dependent on the user's client
349 configuration. A setting of <code>AddDefaultCharset Off</code>
350 disables this functionality. <code>AddDefaultCharset On</code> enables
351 a default charset of <code>iso-8859-1</code>. Any other value is assumed
352 to be the <var>charset</var> to be used, which should be one of the
353 <a href="http://www.iana.org/assignments/character-sets">IANA registered
354 charset values</a> for use in Internet media types (MIME types).
357 <pre class="prettyprint lang-config">AddDefaultCharset utf-8</pre>
360 <p><code class="directive">AddDefaultCharset</code> should only be used when all
361 of the text resources to which it applies are known to be in that
362 character encoding and it is too inconvenient to label their charset
363 individually. One such example is to add the charset parameter
364 to resources containing generated content, such as legacy CGI
365 scripts, that might be vulnerable to cross-site scripting attacks
366 due to user-provided data being included in the output. Note, however,
367 that a better solution is to just fix (or delete) those scripts, since
368 setting a default charset does not protect users that have enabled
369 the "auto-detect character encoding" feature on their browser.</p>
373 <li><code class="directive"><a href="../mod/mod_mime.html#addcharset">AddCharset</a></code></li>
376 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
377 <div class="directive-section"><h2><a name="AllowEncodedSlashes" id="AllowEncodedSlashes">AllowEncodedSlashes</a> <a name="allowencodedslashes" id="allowencodedslashes">Directive</a></h2>
378 <table class="directive">
379 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether encoded path separators in URLs are allowed to
380 be passed through</td></tr>
381 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowEncodedSlashes On|Off|NoDecode</code></td></tr>
382 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowEncodedSlashes Off</code></td></tr>
383 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
384 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
385 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
386 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>
387 NoDecode option available in 2.3.12 and later.</td></tr>
389 <p>The <code class="directive">AllowEncodedSlashes</code> directive allows URLs
390 which contain encoded path separators (<code>%2F</code> for <code>/</code>
391 and additionally <code>%5C</code> for <code>\</code> on accordant systems)
392 to be used in the path info.</p>
394 <p>With the default value, <code>Off</code>, such URLs are refused
395 with a 404 (Not found) error.</p>
397 <p>With the value <code>On</code>, such URLs are accepted, and encoded
398 slashes are decoded like all other encoded characters.</p>
400 <p>With the value <code>NoDecode</code>, such URLs are accepted, but
401 encoded slashes are not decoded but left in their encoded state.</p>
403 <p>Turning <code class="directive">AllowEncodedSlashes</code> <code>On</code> is
404 mostly useful when used in conjunction with <code>PATH_INFO</code>.</p>
406 <div class="note"><h3>Note</h3>
407 <p>If encoded slashes are needed in path info, use of <code>NoDecode</code> is
408 strongly recommended as a security measure. Allowing slashes
409 to be decoded could potentially allow unsafe paths.</p>
414 <li><code class="directive"><a href="#acceptpathinfo">AcceptPathInfo</a></code></li>
417 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
418 <div class="directive-section"><h2><a name="AllowOverride" id="AllowOverride">AllowOverride</a> <a name="allowoverride" id="allowoverride">Directive</a></h2>
419 <table class="directive">
420 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Types of directives that are allowed in
421 <code>.htaccess</code> files</td></tr>
422 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverride All|None|<var>directive-type</var>
423 [<var>directive-type</var>] ...</code></td></tr>
424 <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>
425 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
426 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
427 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
429 <p>When the server finds an <code>.htaccess</code> file (as
430 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>),
431 it needs to know which directives declared in that file can override
432 earlier configuration directives.</p>
434 <div class="note"><h3>Only available in <Directory> sections</h3>
435 <code class="directive">AllowOverride</code> is valid only in
436 <code class="directive"><a href="#directory"><Directory></a></code>
437 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
438 <code class="directive"><a href="#files"><Files></a></code> sections.
441 <p>When this directive is set to <code>None</code> and <code class="directive"><a href="#allowoverridelist">AllowOverrideList</a></code> is set to
442 <code>None</code>, <a href="#accessfilename">.htaccess</a> files are
443 completely ignored. In this case, the server will not even attempt
444 to read <code>.htaccess</code> files in the filesystem.</p>
446 <p>When this directive is set to <code>All</code>, then any
447 directive which has the .htaccess <a href="directive-dict.html#Context">Context</a> is allowed in
448 <code>.htaccess</code> files.</p>
450 <p>The <var>directive-type</var> can be one of the following
451 groupings of directives.</p>
458 Allow use of the authorization directives (<code class="directive"><a href="../mod/mod_authz_dbm.html#authdbmgroupfile">AuthDBMGroupFile</a></code>,
459 <code class="directive"><a href="../mod/mod_authn_dbm.html#authdbmuserfile">AuthDBMUserFile</a></code>,
460 <code class="directive"><a href="../mod/mod_authz_groupfile.html#authgroupfile">AuthGroupFile</a></code>,
461 <code class="directive"><a href="../mod/mod_authn_core.html#authname">AuthName</a></code>,
462 <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>
467 Allow use of the directives controlling document types
468 (<code class="directive"><a href="#errordocument">ErrorDocument</a></code>,
469 <code class="directive"><a href="#forcetype">ForceType</a></code>,
470 <code class="directive"><a href="../mod/mod_negotiation.html#languagepriority">LanguagePriority</a></code>,
471 <code class="directive"><a href="#sethandler">SetHandler</a></code>,
472 <code class="directive"><a href="#setinputfilter">SetInputFilter</a></code>,
473 <code class="directive"><a href="#setoutputfilter">SetOutputFilter</a></code>, and
474 <code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code> Add* and Remove* directives),
475 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>),
476 <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>),
477 <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
478 <code class="directive"><a href="../mod/mod_actions.html#action">Action</a></code> from
479 <code class="module"><a href="../mod/mod_actions.html">mod_actions</a></code>.
485 Allow use of the directives controlling directory indexing
486 (<code class="directive"><a href="../mod/mod_autoindex.html#adddescription">AddDescription</a></code>,
487 <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>,
488 <code class="directive"><a href="../mod/mod_autoindex.html#addiconbytype">AddIconByType</a></code>,
489 <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>,
495 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>
500 <dt>Nonfatal=[Override|Unknown|All]</dt>
503 Allow use of AllowOverride option to treat invalid (unrecognized
504 or disallowed) directives in
505 .htaccess as nonfatal. Instead of causing an Internal Server
506 Error, disallowed or unrecognised directives will be ignored
507 and a warning logged:
509 <li><strong>Nonfatal=Override</strong> treats directives
510 forbidden by AllowOverride as nonfatal.</li>
511 <li><strong>Nonfatal=Unknown</strong> treats unknown directives
512 as nonfatal. This covers typos and directives implemented
513 by a module that's not present.</li>
514 <li><strong>Nonfatal=All</strong> treats both the above as nonfatal.</li>
516 <p>Note that a syntax error in a valid directive will still cause
517 an Internal Server Error.</p>
518 <div class="warning"><h3>Security</h3>
519 Nonfatal errors may have security implications for .htaccess users.
520 For example, if AllowOverride disallows AuthConfig, users'
521 configuration designed to restrict access to a site will be disabled.
525 <dt>Options[=<var>Option</var>,...]</dt>
528 Allow use of the directives controlling specific directory
529 features (<code class="directive"><a href="#options">Options</a></code> and
530 <code class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></code>).
531 An equal sign may be given followed by a comma-separated list, without
532 spaces, of options that may be set using the <code class="directive"><a href="#options">Options</a></code> command.
534 <div class="note"><h3>Implicit disabling of Options</h3>
535 <p>Even though the list of options that may be used in .htaccess files
536 can be limited with this directive, as long as any <code class="directive"><a href="#options">Options</a></code> directive is allowed any
537 other inherited option can be disabled by using the non-relative
538 syntax. In other words, this mechanism cannot force a specific option
539 to remain <em>set</em> while allowing any others to be set.
542 <div class="example"><p><code>
543 AllowOverride Options=Indexes,MultiViews
550 <pre class="prettyprint lang-config">AllowOverride AuthConfig Indexes</pre>
553 <p>In the example above, all directives that are neither in the group
554 <code>AuthConfig</code> nor <code>Indexes</code> cause an internal
557 <div class="note"><p>For security and performance reasons, do not set
558 <code>AllowOverride</code> to anything other than <code>None</code>
559 in your <code><Directory "/"></code> block. Instead, find (or
560 create) the <code><Directory></code> block that refers to the
561 directory where you're actually planning to place a
562 <code>.htaccess</code> file.</p>
567 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
568 <li><code class="directive"><a href="#allowoverridelist">AllowOverrideList</a></code></li>
569 <li><a href="../configuring.html">Configuration Files</a></li>
570 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
573 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
574 <div class="directive-section"><h2><a name="AllowOverrideList" id="AllowOverrideList">AllowOverrideList</a> <a name="allowoverridelist" id="allowoverridelist">Directive</a></h2>
575 <table class="directive">
576 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Individual directives that are allowed in
577 <code>.htaccess</code> files</td></tr>
578 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverrideList None|<var>directive</var>
579 [<var>directive-type</var>] ...</code></td></tr>
580 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowOverrideList None</code></td></tr>
581 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
582 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
583 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
585 <p>When the server finds an <code>.htaccess</code> file (as
586 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>),
587 it needs to know which directives declared in that file can override
588 earlier configuration directives.</p>
590 <div class="note"><h3>Only available in <Directory> sections</h3>
591 <code class="directive">AllowOverrideList</code> is valid only in
592 <code class="directive"><a href="#directory"><Directory></a></code>
593 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
594 <code class="directive"><a href="#files"><Files></a></code> sections.
597 <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>,
598 then <a href="#accessfilename">.htaccess</a> files are completely
599 ignored. In this case, the server will not even attempt to read
600 <code>.htaccess</code> files in the filesystem.</p>
604 <pre class="prettyprint lang-config">AllowOverride None
605 AllowOverrideList Redirect RedirectMatch</pre>
608 <p>In the example above, only the <code>Redirect</code> and
609 <code>RedirectMatch</code> directives are allowed. All others will
610 cause an Internal Server Error.</p>
614 <pre class="prettyprint lang-config">AllowOverride AuthConfig
615 AllowOverrideList CookieTracking CookieName</pre>
618 <p>In the example above, <code class="directive"><a href="#allowoverride">AllowOverride
619 </a></code> grants permission to the <code>AuthConfig</code>
620 directive grouping and <code class="directive">AllowOverrideList</code> grants
621 permission to only two directives from the <code>FileInfo</code> directive
622 grouping. All others will cause an Internal Server Error.</p>
626 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
627 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
628 <li><a href="../configuring.html">Configuration Files</a></li>
629 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
632 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
633 <div class="directive-section"><h2><a name="AsyncFilter" id="AsyncFilter">AsyncFilter</a> <a name="asyncfilter" id="asyncfilter">Directive</a></h2>
634 <table class="directive">
635 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Set the minimum filter type eligible for asynchronous handling</td></tr>
636 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AsyncFilter request|connection|network</code></td></tr>
637 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AsyncFilter request</code></td></tr>
638 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
639 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
640 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
641 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.5.0 and later.</td></tr>
643 <p>This directive controls the minimum filter levels that are eligible
644 for asynchronous handling. This may be necessary to support legacy external
645 filters that did not handle meta buckets correctly.</p>
647 <p>If set to "network", asynchronous handling will be limited to the network
648 filter only. If set to "connection", all connection and network filters
649 will be eligible for asynchronous handling, including <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code>.
650 If set to "request", all filters will be eligible for asynchronous handling.</p>
653 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
654 <div class="directive-section"><h2><a name="CGIMapExtension" id="CGIMapExtension">CGIMapExtension</a> <a name="cgimapextension" id="cgimapextension">Directive</a></h2>
655 <table class="directive">
656 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
658 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIMapExtension <var>cgi-path</var> <var>.extension</var></code></td></tr>
659 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
660 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
661 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
662 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
663 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>NetWare only</td></tr>
665 <p>This directive is used to control how Apache httpd finds the
666 interpreter used to run CGI scripts. For example, setting
667 <code>CGIMapExtension sys:\foo.nlm .foo</code> will
668 cause all CGI script files with a <code>.foo</code> extension to
669 be passed to the FOO interpreter.</p>
672 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
673 <div class="directive-section"><h2><a name="CGIPassAuth" id="CGIPassAuth">CGIPassAuth</a> <a name="cgipassauth" id="cgipassauth">Directive</a></h2>
674 <table class="directive">
675 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables passing HTTP authorization headers to scripts as CGI
677 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIPassAuth On|Off</code></td></tr>
678 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CGIPassAuth Off</code></td></tr>
679 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
680 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig</td></tr>
681 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
682 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
683 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.4.13 and later</td></tr>
685 <p><code class="directive">CGIPassAuth</code> allows scripts access to HTTP
686 authorization headers such as <code>Authorization</code>, which is
687 required for scripts that implement HTTP Basic authentication.
688 Normally these HTTP headers are hidden from scripts. This is to disallow
689 scripts from seeing user ids and passwords used to access the server when
690 HTTP Basic authentication is enabled in the web server. This directive
691 should be used when scripts are allowed to implement HTTP Basic
694 <p>This directive can be used instead of the compile-time setting
695 <code>SECURITY_HOLE_PASS_AUTHORIZATION</code> which has been available
696 in previous versions of Apache HTTP Server.</p>
698 <p>The setting is respected by any modules which use
699 <code>ap_add_common_vars()</code>, such as <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>,
700 <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>,
701 <code class="module"><a href="../mod/mod_proxy_scgi.html">mod_proxy_scgi</a></code>, and so on. Notably, it affects
702 modules which don't handle the request in the usual sense but
703 still use this API; examples of this are <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
704 and <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>. Third-party modules that don't
705 use <code>ap_add_common_vars()</code> may choose to respect the setting
709 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
710 <div class="directive-section"><h2><a name="CGIVar" id="CGIVar">CGIVar</a> <a name="cgivar" id="cgivar">Directive</a></h2>
711 <table class="directive">
712 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls how some CGI variables are set</td></tr>
713 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIVar <var>variable</var> <var>rule</var></code></td></tr>
714 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
715 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
716 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
717 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
718 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.4.21 and later</td></tr>
720 <p>This directive controls how some CGI variables are set.</p>
722 <p><strong>REQUEST_URI</strong> rules:</p>
724 <dt><code>original-uri</code> (default)</dt>
725 <dd>The value is taken from the original request line, and will not
726 reflect internal redirects or subrequests which change the requested
728 <dt><code>current-uri</code></dt>
729 <dd>The value reflects the resource currently being processed,
730 which may be different than the original request from the client
731 due to internal redirects or subrequests.</dd>
735 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
736 <div class="directive-section"><h2><a name="ContentDigest" id="ContentDigest">ContentDigest</a> <a name="contentdigest" id="contentdigest">Directive</a></h2>
737 <table class="directive">
738 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables the generation of <code>Content-MD5</code> HTTP Response
740 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ContentDigest On|Off</code></td></tr>
741 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ContentDigest Off</code></td></tr>
742 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
743 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
744 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
745 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
747 <p>This directive enables the generation of
748 <code>Content-MD5</code> headers as defined in RFC1864
749 respectively RFC2616.</p>
751 <p>MD5 is an algorithm for computing a "message digest"
752 (sometimes called "fingerprint") of arbitrary-length data, with
753 a high degree of confidence that any alterations in the data
754 will be reflected in alterations in the message digest.</p>
756 <p>The <code>Content-MD5</code> header provides an end-to-end
757 message integrity check (MIC) of the entity-body. A proxy or
758 client may check this header for detecting accidental
759 modification of the entity-body in transit. Example header:</p>
761 <div class="example"><p><code>
762 Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
765 <p>Note that this can cause performance problems on your server
766 since the message digest is computed on every request (the
767 values are not cached).</p>
769 <p><code>Content-MD5</code> is only sent for documents served
770 by the <code class="module"><a href="../mod/core.html">core</a></code>, and not by any module. For example,
771 SSI documents, output from CGI scripts, and byte range responses
772 do not have this header.</p>
775 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
776 <div class="directive-section"><h2><a name="DefaultRuntimeDir" id="DefaultRuntimeDir">DefaultRuntimeDir</a> <a name="defaultruntimedir" id="defaultruntimedir">Directive</a></h2>
777 <table class="directive">
778 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server run-time files</td></tr>
779 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultRuntimeDir <var>directory-path</var></code></td></tr>
780 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultRuntimeDir DEFAULT_REL_RUNTIMEDIR (logs/)</code></td></tr>
781 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
782 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
783 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
784 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.4.2 and later</td></tr>
786 <p>The <code class="directive">DefaultRuntimeDir</code> directive sets the
787 directory in which the server will create various run-time files
788 (shared memory, locks, etc.). If set as a relative path, the full path
789 will be relative to <code class="directive">ServerRoot</code>.</p>
791 <p><strong>Example</strong></p>
792 <pre class="prettyprint lang-config">DefaultRuntimeDir scratch/</pre>
795 <p>The default location of <code class="directive">DefaultRuntimeDir</code> may be
796 modified by changing the <code>DEFAULT_REL_RUNTIMEDIR</code> #define
799 <p>Note: <code class="directive">ServerRoot</code> should be specified before this
800 directive is used. Otherwise, the default value of <code class="directive">ServerRoot</code>
801 would be used to set the base directory.</p>
806 <li><a href="../misc/security_tips.html#serverroot">the
807 security tips</a> for information on how to properly set
808 permissions on the <code class="directive">ServerRoot</code></li>
811 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
812 <div class="directive-section"><h2><a name="DefaultType" id="DefaultType">DefaultType</a> <a name="defaulttype" id="defaulttype">Directive</a></h2>
813 <table class="directive">
814 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>This directive has no effect other than to emit warnings
815 if the value is not <code>none</code>. In prior versions, DefaultType
816 would specify a default media type to assign to response content for
817 which no other media type configuration could be found.
819 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultType <var>media-type|none</var></code></td></tr>
820 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultType none</code></td></tr>
821 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
822 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
823 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
824 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
825 <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.
828 <p>This directive has been disabled. For backwards compatibility
829 of configuration files, it may be specified with the value
830 <code>none</code>, meaning no default media type. For example:</p>
832 <pre class="prettyprint lang-config">DefaultType None</pre>
835 <p><code>DefaultType None</code> is only available in
836 httpd-2.2.7 and later.</p>
838 <p>Use the mime.types configuration file and the
839 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code> to configure media
840 type assignments via file extensions, or the
841 <code class="directive"><a href="#forcetype">ForceType</a></code> directive to configure
842 the media type for specific resources. Otherwise, the server will
843 send the response without a Content-Type header field and the
844 recipient may attempt to guess the media type.</p>
847 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
848 <div class="directive-section"><h2><a name="Define" id="Define">Define</a> <a name="define" id="define">Directive</a></h2>
849 <table class="directive">
850 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Define a variable</td></tr>
851 <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>
852 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
853 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
854 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
856 <p>In its one parameter form, <code class="directive">Define</code> is equivalent
857 to passing the <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>. It
858 can be used to toggle the use of
859 <code class="directive"><a href="#ifdefine"><IfDefine></a></code> sections
860 without needing to alter <code>-D</code> arguments in any startup
863 <p>In addition to that, if the second parameter is given, a config variable
864 is set to this value. The variable can be used in the configuration using
865 the <code>${VAR}</code> syntax. The variable is always globally defined
866 and not limited to the scope of the surrounding config section.</p>
868 <pre class="prettyprint lang-config"><IfDefine TEST>
869 Define servername test.example.com
871 <IfDefine !TEST>
872 Define servername www.example.com
876 DocumentRoot "/var/www/${servername}/htdocs"</pre>
879 <p>Variable names may not contain colon ":" characters, to avoid clashes
880 with <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>'s syntax.</p>
882 <p>While this directive is supported in virtual host context,
883 the changes it makes are visible to any later configuration
884 directives, beyond any enclosing virtual host</p>
887 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
888 <div class="directive-section"><h2><a name="Directory" id="Directory"><Directory></a> <a name="directory" id="directory">Directive</a></h2>
889 <table class="directive">
890 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose a group of directives that apply only to the
891 named file-system directory, sub-directories, and their contents.</td></tr>
892 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Directory <var>directory-path</var>>
893 ... </Directory></code></td></tr>
894 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
895 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
896 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
898 <p><code class="directive"><Directory></code> and
899 <code></Directory></code> are used to enclose a group of
900 directives that will apply only to the named directory,
901 sub-directories of that directory, and the files within the respective
902 directories. Any directive that is allowed
903 in a directory context may be used. <var>Directory-path</var> is
904 either the full path to a directory, or a wild-card string using
905 Unix shell-style matching. In a wild-card string, <code>?</code> matches
906 any single character, and <code>*</code> matches any sequences of
907 characters. You may also use <code>[]</code> character ranges. None
908 of the wildcards match a `/' character, so <code><Directory
909 "/*/public_html"></code> will not match
910 <code>/home/user/public_html</code>, but <code><Directory
911 "/home/*/public_html"></code> will match. Example:</p>
913 <pre class="prettyprint lang-config"><Directory "/usr/local/httpd/htdocs">
914 Options Indexes FollowSymLinks
915 </Directory></pre>
918 <p>Directory paths <em>may</em> be quoted, if you like, however, it
919 <em>must</em> be quoted if the path contains spaces. This is because a
920 space would otherwise indicate the end of an argument.</p>
923 <p>Be careful with the <var>directory-path</var> arguments:
924 They have to literally match the filesystem path which Apache httpd uses
925 to access the files. Directives applied to a particular
926 <code><Directory></code> will not apply to files accessed from
927 that same directory via a different path, such as via different symbolic
931 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular
932 expressions</a> can also be used, with the addition of the
933 <code>~</code> character. For example:</p>
935 <pre class="prettyprint lang-config"><Directory ~ "^/www/[0-9]{3}">
937 </Directory></pre>
940 <p>would match directories in <code>/www/</code> that consisted of
943 <p>If multiple (non-regular expression) <code class="directive"><Directory></code> sections
944 match the directory (or one of its parents) containing a document,
945 then the directives are applied in the order of shortest match
946 first, interspersed with the directives from the <a href="#accessfilename">.htaccess</a> files. For example,
949 <pre class="prettyprint lang-config"><Directory "/">
953 <Directory "/home">
954 AllowOverride FileInfo
955 </Directory></pre>
958 <p>for access to the document <code>/home/web/dir/doc.html</code>
962 <li>Apply directive <code>AllowOverride None</code>
963 (disabling <code>.htaccess</code> files).</li>
965 <li>Apply directive <code>AllowOverride FileInfo</code> (for
966 directory <code>/home</code>).</li>
968 <li>Apply any <code>FileInfo</code> directives in
969 <code>/home/.htaccess</code>, <code>/home/web/.htaccess</code> and
970 <code>/home/web/dir/.htaccess</code> in that order.</li>
973 <p>Regular expressions are not considered until after all of the
974 normal sections have been applied. Then all of the regular
975 expressions are tested in the order they appeared in the
976 configuration file. For example, with</p>
978 <pre class="prettyprint lang-config"><Directory ~ "abc$">
979 # ... directives here ...
980 </Directory></pre>
983 <p>the regular expression section won't be considered until after
984 all normal <code class="directive"><Directory></code>s and
985 <code>.htaccess</code> files have been applied. Then the regular
986 expression will match on <code>/home/abc/public_html/abc</code> and
987 the corresponding <code class="directive"><Directory></code> will
990 <p><strong>Note that the default access for
991 <code><Directory "/"></code> is to permit all access.
992 This means that Apache httpd will serve any file mapped from an URL. It is
993 recommended that you change this with a block such
996 <pre class="prettyprint lang-config"><Directory "/">
998 </Directory></pre>
1001 <p><strong>and then override this for directories you
1002 <em>want</em> accessible. See the <a href="../misc/security_tips.html">Security Tips</a> page for more
1003 details.</strong></p>
1005 <p>The directory sections occur in the <code>httpd.conf</code> file.
1006 <code class="directive"><Directory></code> directives
1007 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>
1011 <li><a href="../sections.html">How <Directory>,
1012 <Location> and <Files> sections work</a> for an
1013 explanation of how these different sections are combined when a
1014 request is received</li>
1017 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1018 <div class="directive-section"><h2><a name="DirectoryMatch" id="DirectoryMatch"><DirectoryMatch></a> <a name="directorymatch" id="directorymatch">Directive</a></h2>
1019 <table class="directive">
1020 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose directives that apply to
1021 the contents of file-system directories matching a regular expression.</td></tr>
1022 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><DirectoryMatch <var>regex</var>>
1023 ... </DirectoryMatch></code></td></tr>
1024 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1025 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1026 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1028 <p><code class="directive"><DirectoryMatch></code> and
1029 <code></DirectoryMatch></code> are used to enclose a group
1030 of directives which will apply only to the named directory (and the files within),
1031 the same as <code class="directive"><a href="#directory"><Directory></a></code>.
1032 However, it takes as an argument a
1033 <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>. For example:</p>
1035 <pre class="prettyprint lang-config"><DirectoryMatch "^/www/(.+/)?[0-9]{3}/">
1037 </DirectoryMatch></pre>
1040 <p>matches directories in <code>/www/</code> (or any subdirectory thereof)
1041 that consist of three numbers.</p>
1043 <div class="note"><h3>Compatability</h3>
1044 Prior to 2.3.9, this directive implicitly applied to sub-directories
1045 (like <code class="directive"><a href="#directory"><Directory></a></code>) and
1046 could not match the end of line symbol ($). In 2.3.9 and later,
1047 only directories that match the expression are affected by the enclosed
1051 <div class="note"><h3>Trailing Slash</h3>
1052 This directive applies to requests for directories that may or may
1053 not end in a trailing slash, so expressions that are anchored to the
1054 end of line ($) must be written with care.
1057 <p>From 2.4.8 onwards, named groups and backreferences are captured and
1058 written to the environment with the corresponding name prefixed with
1059 "MATCH_" and in upper case. This allows elements of paths to be referenced
1060 from within <a href="../expr.html">expressions</a> and modules like
1061 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
1062 (unnamed) backreferences are ignored. Use named groups instead.</p>
1064 <pre class="prettyprint lang-config"><DirectoryMatch "^/var/www/combined/(?<sitename>[^/]+)">
1065 Require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
1066 </DirectoryMatch></pre>
1071 <li><code class="directive"><a href="#directory"><Directory></a></code> for
1072 a description of how regular expressions are mixed in with normal
1073 <code class="directive"><Directory></code>s</li>
1074 <li><a href="../sections.html">How <Directory>, <Location> and
1075 <Files> sections work</a> for an explanation of how these different
1076 sections are combined when a request is received</li>
1079 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1080 <div class="directive-section"><h2><a name="DocumentRoot" id="DocumentRoot">DocumentRoot</a> <a name="documentroot" id="documentroot">Directive</a></h2>
1081 <table class="directive">
1082 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory that forms the main document tree visible
1083 from the web</td></tr>
1084 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DocumentRoot <var>directory-path</var></code></td></tr>
1085 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DocumentRoot "/usr/local/apache/htdocs"</code></td></tr>
1086 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1087 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1088 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1090 <p>This directive sets the directory from which <code class="program"><a href="../programs/httpd.html">httpd</a></code>
1091 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
1092 path from the requested URL to the document root to make the
1093 path to the document. Example:</p>
1095 <pre class="prettyprint lang-config">DocumentRoot "/usr/web"</pre>
1098 <p>then an access to
1099 <code>http://my.example.com/index.html</code> refers to
1100 <code>/usr/web/index.html</code>. If the <var>directory-path</var> is
1101 not absolute then it is assumed to be relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1103 <p>The <code class="directive">DocumentRoot</code> should be specified without
1104 a trailing slash.</p>
1108 <li><a href="../urlmapping.html#documentroot">Mapping URLs to Filesystem
1112 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1113 <div class="directive-section"><h2><a name="Else" id="Else"><Else></a> <a name="else" id="else">Directive</a></h2>
1114 <table class="directive">
1115 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if the condition of a
1116 previous <code class="directive"><a href="#if"><If></a></code> or
1117 <code class="directive"><a href="#elseif"><ElseIf></a></code> section is not
1118 satisfied by a request at runtime</td></tr>
1119 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Else> ... </Else></code></td></tr>
1120 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1121 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1122 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1123 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1125 <p>The <code class="directive"><Else></code> applies the enclosed
1126 directives if and only if the most recent
1127 <code class="directive"><If></code> or
1128 <code class="directive"><ElseIf></code> section
1129 in the same scope has not been applied.
1130 For example: In </p>
1132 <pre class="prettyprint lang-config"><If "-z req('Host')">
1140 <p> The <code class="directive"><If></code> would match HTTP/1.0
1141 requests without a <var>Host:</var> header and the
1142 <code class="directive"><Else></code> would match requests
1143 with a <var>Host:</var> header.</p>
1148 <li><code class="directive"><a href="#if"><If></a></code></li>
1149 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
1150 <li><a href="../sections.html">How <Directory>, <Location>,
1151 <Files> sections work</a> for an explanation of how these
1152 different sections are combined when a request is received.
1153 <code class="directive"><If></code>,
1154 <code class="directive"><ElseIf></code>, and
1155 <code class="directive"><Else></code> are applied last.</li>
1158 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1159 <div class="directive-section"><h2><a name="ElseIf" id="ElseIf"><ElseIf></a> <a name="elseif" id="elseif">Directive</a></h2>
1160 <table class="directive">
1161 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is satisfied
1162 by a request at runtime while the condition of a previous
1163 <code class="directive"><a href="#if"><If></a></code> or
1164 <code class="directive"><ElseIf></code> section is not
1166 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><ElseIf <var>expression</var>> ... </ElseIf></code></td></tr>
1167 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1168 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1169 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1170 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1172 <p>The <code class="directive"><ElseIf></code> applies the enclosed
1173 directives if and only if both the given condition evaluates to true and
1174 the most recent <code class="directive"><If></code> or
1175 <code class="directive"><ElseIf></code> section in the same scope has
1176 not been applied. For example: In </p>
1178 <pre class="prettyprint lang-config"><If "-R '10.1.0.0/16'">
1181 <ElseIf "-R '10.0.0.0/8'">
1189 <p>The <code class="directive"><ElseIf></code> would match if
1190 the remote address of a request belongs to the subnet 10.0.0.0/8 but
1191 not to the subnet 10.1.0.0/16.</p>
1196 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
1197 for a complete reference and more examples.</li>
1198 <li><code class="directive"><a href="#if"><If></a></code></li>
1199 <li><code class="directive"><a href="#else"><Else></a></code></li>
1200 <li><a href="../sections.html">How <Directory>, <Location>,
1201 <Files> sections work</a> for an explanation of how these
1202 different sections are combined when a request is received.
1203 <code class="directive"><If></code>,
1204 <code class="directive"><ElseIf></code>, and
1205 <code class="directive"><Else></code> are applied last.</li>
1208 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1209 <div class="directive-section"><h2><a name="EnableMMAP" id="EnableMMAP">EnableMMAP</a> <a name="enablemmap" id="enablemmap">Directive</a></h2>
1210 <table class="directive">
1211 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use memory-mapping to read files during delivery</td></tr>
1212 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableMMAP On|Off</code></td></tr>
1213 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableMMAP On</code></td></tr>
1214 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1215 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1216 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1217 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1219 <p>This directive controls whether the <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use
1220 memory-mapping if it needs to read the contents of a file during
1221 delivery. By default, when the handling of a request requires
1222 access to the data within a file -- for example, when delivering a
1223 server-parsed file using <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> -- Apache httpd
1224 memory-maps the file if the OS supports it.</p>
1226 <p>This memory-mapping sometimes yields a performance improvement.
1227 But in some environments, it is better to disable the memory-mapping
1228 to prevent operational problems:</p>
1231 <li>On some multiprocessor systems, memory-mapping can reduce the
1232 performance of the <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</li>
1233 <li>Deleting or truncating a file while <code class="program"><a href="../programs/httpd.html">httpd</a></code>
1234 has it memory-mapped can cause <code class="program"><a href="../programs/httpd.html">httpd</a></code> to
1235 crash with a segmentation fault.
1239 <p>For server configurations that are vulnerable to these problems,
1240 you should disable memory-mapping of delivered files by specifying:</p>
1242 <pre class="prettyprint lang-config">EnableMMAP Off</pre>
1245 <p>For NFS mounted files, this feature may be disabled explicitly for
1246 the offending files by specifying:</p>
1248 <pre class="prettyprint lang-config"><Directory "/path-to-nfs-files">
1250 </Directory></pre>
1254 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1255 <div class="directive-section"><h2><a name="EnableSendfile" id="EnableSendfile">EnableSendfile</a> <a name="enablesendfile" id="enablesendfile">Directive</a></h2>
1256 <table class="directive">
1257 <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>
1258 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableSendfile On|Off</code></td></tr>
1259 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableSendfile Off</code></td></tr>
1260 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1261 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1262 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1263 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1264 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Default changed to Off in
1265 version 2.3.9.</td></tr>
1267 <p>This directive controls whether <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use the
1268 sendfile support from the kernel to transmit file contents to the client.
1269 By default, when the handling of a request requires no access
1270 to the data within a file -- for example, when delivering a
1271 static file -- Apache httpd uses sendfile to deliver the file contents
1272 without ever reading the file if the OS supports it.</p>
1274 <p>This sendfile mechanism avoids separate read and send operations,
1275 and buffer allocations. But on some platforms or within some
1276 filesystems, it is better to disable this feature to avoid
1277 operational problems:</p>
1280 <li>Some platforms may have broken sendfile support that the build
1281 system did not detect, especially if the binaries were built on
1282 another box and moved to such a machine with broken sendfile
1284 <li>On Linux the use of sendfile triggers TCP-checksum
1285 offloading bugs on certain networking cards when using IPv6.</li>
1286 <li>On Linux on Itanium, <code>sendfile</code> may be unable to handle
1287 files over 2GB in size.</li>
1288 <li>With a network-mounted <code class="directive"><a href="#documentroot">DocumentRoot</a></code> (e.g., NFS, SMB, CIFS, FUSE),
1289 the kernel may be unable to serve the network file through
1293 <p>For server configurations that are not vulnerable to these problems,
1294 you may enable this feature by specifying:</p>
1296 <pre class="prettyprint lang-config">EnableSendfile On</pre>
1299 <p>For network mounted files, this feature may be disabled explicitly
1300 for the offending files by specifying:</p>
1302 <pre class="prettyprint lang-config"><Directory "/path-to-nfs-files">
1304 </Directory></pre>
1306 <p>Please note that the per-directory and .htaccess configuration
1307 of <code class="directive">EnableSendfile</code> is not supported by
1308 <code class="module"><a href="../mod/mod_cache_disk.html">mod_cache_disk</a></code>.
1309 Only global definition of <code class="directive">EnableSendfile</code>
1310 is taken into account by the module.
1314 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1315 <div class="directive-section"><h2><a name="Error" id="Error">Error</a> <a name="error" id="error">Directive</a></h2>
1316 <table class="directive">
1317 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Abort configuration parsing with a custom error message</td></tr>
1318 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Error <var>message</var></code></td></tr>
1319 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1320 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1321 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1322 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.3.9 and later</td></tr>
1324 <p>If an error can be detected within the configuration, this
1325 directive can be used to generate a custom error message, and halt
1326 configuration parsing. The typical use is for reporting required
1327 modules which are missing from the configuration.</p>
1329 <pre class="prettyprint lang-config"># Example
1330 # ensure that mod_include is loaded
1331 <IfModule !include_module>
1332 Error "mod_include is required by mod_foo. Load it with LoadModule."
1335 # ensure that exactly one of SSL,NOSSL is defined
1336 <IfDefine SSL>
1337 <IfDefine NOSSL>
1338 Error "Both SSL and NOSSL are defined. Define only one of them."
1341 <IfDefine !SSL>
1342 <IfDefine !NOSSL>
1343 Error "Either SSL or NOSSL must be defined."
1345 </IfDefine></pre>
1350 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1351 <div class="directive-section"><h2><a name="ErrorDocument" id="ErrorDocument">ErrorDocument</a> <a name="errordocument" id="errordocument">Directive</a></h2>
1352 <table class="directive">
1353 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>What the server will return to the client
1354 in case of an error</td></tr>
1355 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ErrorDocument <var>error-code</var> <var>document</var></code></td></tr>
1356 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1357 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1358 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1359 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1361 <p>In the event of a problem or error, Apache httpd can be configured
1362 to do one of four things,</p>
1365 <li>output a simple hardcoded error message</li>
1367 <li>output a customized message</li>
1369 <li>internally redirect to a local <var>URL-path</var> to handle the
1372 <li>redirect to an external <var>URL</var> to handle the
1376 <p>The first option is the default, while options 2-4 are
1377 configured using the <code class="directive">ErrorDocument</code>
1378 directive, which is followed by the HTTP response code and a URL
1379 or a message. Apache httpd will sometimes offer additional information
1380 regarding the problem/error.</p>
1382 <p>From 2.4.13, <a href="../expr.html">expression syntax</a> can be
1383 used inside the directive to produce dynamic strings and URLs.</p>
1385 <p>URLs can begin with a slash (/) for local web-paths (relative
1386 to the <code class="directive"><a href="#documentroot">DocumentRoot</a></code>), or be a
1387 full URL which the client can resolve. Alternatively, a message
1388 can be provided to be displayed by the browser. Note that deciding
1389 whether the parameter is an URL, a path or a message is performed
1390 before any expression is parsed. Examples:</p>
1392 <pre class="prettyprint lang-config">ErrorDocument 500 http://example.com/cgi-bin/server-error.cgi
1393 ErrorDocument 404 /errors/bad_urls.php
1394 ErrorDocument 401 /subscription_info.html
1395 ErrorDocument 403 "Sorry, can't allow you access today"
1396 ErrorDocument 403 Forbidden!
1397 ErrorDocument 403 /errors/forbidden.py?referrer=%{escape:%{HTTP_REFERER}}</pre>
1400 <p>Additionally, the special value <code>default</code> can be used
1401 to specify Apache httpd's simple hardcoded message. While not required
1402 under normal circumstances, <code>default</code> will restore
1403 Apache httpd's simple hardcoded message for configurations that would
1404 otherwise inherit an existing <code class="directive">ErrorDocument</code>.</p>
1406 <pre class="prettyprint lang-config">ErrorDocument 404 /cgi-bin/bad_urls.pl
1408 <Directory "/web/docs">
1409 ErrorDocument 404 default
1410 </Directory></pre>
1413 <p>Note that when you specify an <code class="directive">ErrorDocument</code>
1414 that points to a remote URL (ie. anything with a method such as
1415 <code>http</code> in front of it), Apache HTTP Server will send a redirect to the
1416 client to tell it where to find the document, even if the
1417 document ends up being on the same server. This has several
1418 implications, the most important being that the client will not
1419 receive the original error status code, but instead will
1420 receive a redirect status code. This in turn can confuse web
1421 robots and other clients which try to determine if a URL is
1422 valid using the status code. In addition, if you use a remote
1423 URL in an <code>ErrorDocument 401</code>, the client will not
1424 know to prompt the user for a password since it will not
1425 receive the 401 status code. Therefore, <strong>if you use an
1426 <code>ErrorDocument 401</code> directive, then it must refer to a local
1427 document.</strong></p>
1429 <p>Microsoft Internet Explorer (MSIE) will by default ignore
1430 server-generated error messages when they are "too small" and substitute
1431 its own "friendly" error messages. The size threshold varies depending on
1432 the type of error, but in general, if you make your error document
1433 greater than 512 bytes, then MSIE will show the server-generated
1434 error rather than masking it. More information is available in
1435 Microsoft Knowledge Base article <a href="http://support.microsoft.com/default.aspx?scid=kb;en-us;Q294807">Q294807</a>.</p>
1437 <p>Although most error messages can be overridden, there are certain
1438 circumstances where the internal messages are used regardless of the
1439 setting of <code class="directive"><a href="#errordocument">ErrorDocument</a></code>. In
1440 particular, if a malformed request is detected, normal request processing
1441 will be immediately halted and the internal error message returned.
1442 This is necessary to guard against security problems caused by
1445 <p>If you are using mod_proxy, you may wish to enable
1446 <code class="directive"><a href="../mod/mod_proxy.html#proxyerroroverride">ProxyErrorOverride</a></code> so that you can provide
1447 custom error messages on behalf of your Origin servers. If you don't enable ProxyErrorOverride,
1448 Apache httpd will not generate custom error documents for proxied content.</p>
1452 <li><a href="../custom-error.html">documentation of
1453 customizable responses</a></li>
1456 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1457 <div class="directive-section"><h2><a name="ErrorLog" id="ErrorLog">ErrorLog</a> <a name="errorlog" id="errorlog">Directive</a></h2>
1458 <table class="directive">
1459 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Location where the server will log errors</td></tr>
1460 <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>
1461 <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>
1462 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1463 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1464 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1466 <p>The <code class="directive">ErrorLog</code> directive sets the name of
1467 the file to which the server will log any errors it encounters. If
1468 the <var>file-path</var> is not absolute then it is assumed to be
1469 relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1471 <pre class="prettyprint lang-config">ErrorLog "/var/log/httpd/error_log"</pre>
1474 <p>If the <var>file-path</var>
1475 begins with a pipe character "<code>|</code>" then it is assumed to be a
1476 command to spawn to handle the error log.</p>
1478 <pre class="prettyprint lang-config">ErrorLog "|/usr/local/bin/httpd_errors"</pre>
1481 <p>See the notes on <a href="../logs.html#piped">piped logs</a> for
1482 more information.</p>
1484 <p>Using <code>syslog</code> instead of a filename enables logging
1485 via syslogd(8) if the system supports it and if <code class="module"><a href="../mod/mod_syslog.html">mod_syslog</a></code>
1486 is loaded. The default is to use syslog facility <code>local7</code>,
1487 but you can override this by using the <code>syslog:<var>facility</var></code>
1488 syntax where <var>facility</var> can be one of the names usually documented in
1489 syslog(1). The facility is effectively global, and if it is changed
1490 in individual virtual hosts, the final facility specified affects the
1493 <pre class="prettyprint lang-config">ErrorLog syslog:user</pre>
1496 <p>Additional modules can provide their own ErrorLog providers. The syntax
1497 is similar to the <code>syslog</code> example above.</p>
1499 <p>SECURITY: See the <a href="../misc/security_tips.html#serverroot">security tips</a>
1500 document for details on why your security could be compromised
1501 if the directory where log files are stored is writable by
1502 anyone other than the user that starts the server.</p>
1503 <div class="warning"><h3>Note</h3>
1504 <p>When entering a file path on non-Unix platforms, care should be taken
1505 to make sure that only forward slashes are used even though the platform
1506 may allow the use of back slashes. In general it is a good idea to always
1507 use forward slashes throughout the configuration files.</p>
1512 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1513 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1516 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1517 <div class="directive-section"><h2><a name="ErrorLogFormat" id="ErrorLogFormat">ErrorLogFormat</a> <a name="errorlogformat" id="errorlogformat">Directive</a></h2>
1518 <table class="directive">
1519 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Format specification for error log entries</td></tr>
1520 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code> ErrorLogFormat [connection|request] <var>format</var></code></td></tr>
1521 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1522 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1523 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1525 <p><code class="directive">ErrorLogFormat</code> allows to specify what
1526 supplementary information is logged in the error log in addition to the
1527 actual log message.</p>
1529 <pre class="prettyprint lang-config">#Simple example
1530 ErrorLogFormat "[%t] [%l] [pid %P] %F: %E: [client %a] %M"</pre>
1533 <p>Specifying <code>connection</code> or <code>request</code> as first
1534 parameter allows to specify additional formats, causing additional
1535 information to be logged when the first message is logged for a specific
1536 connection or request, respectively. This additional information is only
1537 logged once per connection/request. If a connection or request is processed
1538 without causing any log message, the additional information is not logged
1541 <p>It can happen that some format string items do not produce output. For
1542 example, the Referer header is only present if the log message is
1543 associated to a request and the log message happens at a time when the
1544 Referer header has already been read from the client. If no output is
1545 produced, the default behavior is to delete everything from the preceding
1546 space character to the next space character. This means the log line is
1547 implicitly divided into fields on non-whitespace to whitespace transitions.
1548 If a format string item does not produce output, the whole field is
1549 omitted. For example, if the remote address <code>%a</code> in the log
1550 format <code>[%t] [%l] [%a] %M </code> is not available, the surrounding
1551 brackets are not logged either. Space characters can be escaped with a
1552 backslash to prevent them from delimiting a field. The combination '% '
1553 (percent space) is a zero-width field delimiter that does not produce any
1556 <p>The above behavior can be changed by adding modifiers to the format
1557 string item. A <code>-</code> (minus) modifier causes a minus to be logged if the
1558 respective item does not produce any output. In once-per-connection/request
1559 formats, it is also possible to use the <code>+</code> (plus) modifier. If an
1560 item with the plus modifier does not produce any output, the whole line is
1563 <p>A number as modifier can be used to assign a log severity level to a
1564 format item. The item will only be logged if the severity of the log
1565 message is not higher than the specified log severity level. The number can
1566 range from 1 (alert) over 4 (warn) and 7 (debug) to 15 (trace8).</p>
1568 <p>For example, here's what would happen if you added modifiers to
1569 the <code>%{Referer}i</code> token, which logs the
1570 <code>Referer</code> request header.</p>
1572 <table class="bordered"><tr class="header"><th>Modified Token</th><th>Meaning</th></tr>
1574 <td><code>%-{Referer}i</code></td>
1575 <td>Logs a <code>-</code> if <code>Referer</code> is not set.</td>
1578 <td><code>%+{Referer}i</code></td>
1579 <td>Omits the entire line if <code>Referer</code> is not set.</td>
1582 <td><code>%4{Referer}i</code></td>
1583 <td>Logs the <code>Referer</code> only if the log message severity
1584 is higher than 4.</td>
1588 <p>Some format string items accept additional parameters in braces.</p>
1590 <table class="bordered"><tr class="header"><th>Format String</th> <th>Description</th></tr>
1591 <tr><td><code>%%</code></td>
1592 <td>The percent sign</td></tr>
1593 <tr class="odd"><td><code>%a</code></td>
1594 <td>Client IP address and port of the request</td></tr>
1595 <tr><td><code>%{c}a</code></td>
1596 <td>Underlying peer IP address and port of the connection (see the
1597 <code class="module"><a href="../mod/mod_remoteip.html">mod_remoteip</a></code> module)</td></tr>
1598 <tr class="odd"><td><code>%A</code></td>
1599 <td>Local IP-address and port</td></tr>
1600 <tr><td><code>%{<em>name</em>}e</code></td>
1601 <td>Request environment variable <em>name</em></td></tr>
1602 <tr class="odd"><td><code>%E</code></td>
1603 <td>APR/OS error status code and string</td></tr>
1604 <tr><td><code>%F</code></td>
1605 <td>Source file name and line number of the log call</td></tr>
1606 <tr class="odd"><td><code>%{<em>name</em>}i</code></td>
1607 <td>Request header <em>name</em></td></tr>
1608 <tr><td><code>%k</code></td>
1609 <td>Number of keep-alive requests on this connection</td></tr>
1610 <tr class="odd"><td><code>%l</code></td>
1611 <td>Loglevel of the message</td></tr>
1612 <tr><td><code>%L</code></td>
1613 <td>Log ID of the request</td></tr>
1614 <tr class="odd"><td><code>%{c}L</code></td>
1615 <td>Log ID of the connection</td></tr>
1616 <tr><td><code>%{C}L</code></td>
1617 <td>Log ID of the connection if used in connection scope, empty otherwise</td></tr>
1618 <tr class="odd"><td><code>%m</code></td>
1619 <td>Name of the module logging the message</td></tr>
1620 <tr><td><code>%M</code></td>
1621 <td>The actual log message</td></tr>
1622 <tr class="odd"><td><code>%{<em>name</em>}n</code></td>
1623 <td>Request note <em>name</em></td></tr>
1624 <tr><td><code>%P</code></td>
1625 <td>Process ID of current process</td></tr>
1626 <tr class="odd"><td><code>%T</code></td>
1627 <td>Thread ID of current thread</td></tr>
1628 <tr><td><code>%{g}T</code></td>
1629 <td>System unique thread ID of current thread (the same ID as
1630 displayed by e.g. <code>top</code>; currently Linux only)</td></tr>
1631 <tr class="odd"><td><code>%t</code></td>
1632 <td>The current time</td></tr>
1633 <tr><td><code>%{u}t</code></td>
1634 <td>The current time including micro-seconds</td></tr>
1635 <tr class="odd"><td><code>%{cu}t</code></td>
1636 <td>The current time in compact ISO 8601 format, including
1637 micro-seconds</td></tr>
1638 <tr><td><code>%v</code></td>
1639 <td>The canonical <code class="directive"><a href="#servername">ServerName</a></code>
1640 of the current server.</td></tr>
1641 <tr class="odd"><td><code>%V</code></td>
1642 <td>The server name of the server serving the request according to the
1643 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code>
1645 <tr><td><code>\ </code> (backslash space)</td>
1646 <td>Non-field delimiting space</td></tr>
1647 <tr class="odd"><td><code>% </code> (percent space)</td>
1648 <td>Field delimiter (no output)</td></tr>
1651 <p>The log ID format <code>%L</code> produces a unique id for a connection
1652 or request. This can be used to correlate which log lines belong to the
1653 same connection or request, which request happens on which connection.
1654 A <code>%L</code> format string is also available in
1655 <code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code> to allow to correlate access log entries
1656 with error log lines. If <code class="module"><a href="../mod/mod_unique_id.html">mod_unique_id</a></code> is loaded, its
1657 unique id will be used as log ID for requests.</p>
1659 <pre class="prettyprint lang-config">#Example (default format for threaded MPMs)
1660 ErrorLogFormat "[%{u}t] [%-m:%l] [pid %P:tid %T] %7F: %E: [client\ %a] %M% ,\ referer\ %{Referer}i"</pre>
1663 <p>This would result in error messages such as:</p>
1665 <div class="example"><p><code>
1666 [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
1669 <p>Notice that, as discussed above, some fields are omitted
1670 entirely because they are not defined.</p>
1672 <pre class="prettyprint lang-config">#Example (similar to the 2.2.x format)
1673 ErrorLogFormat "[%t] [%l] %7F: %E: [client\ %a] %M% ,\ referer\ %{Referer}i"</pre>
1676 <pre class="prettyprint lang-config">#Advanced example with request/connection log IDs
1677 ErrorLogFormat "[%{uc}t] [%-m:%-l] [R:%L] [C:%{C}L] %7F: %E: %M"
1678 ErrorLogFormat request "[%{uc}t] [R:%L] Request %k on C:%{c}L pid:%P tid:%T"
1679 ErrorLogFormat request "[%{uc}t] [R:%L] UA:'%+{User-Agent}i'"
1680 ErrorLogFormat request "[%{uc}t] [R:%L] Referer:'%+{Referer}i'"
1681 ErrorLogFormat connection "[%{uc}t] [C:%{c}L] local\ %a remote\ %A"</pre>
1687 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
1688 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1689 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1692 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1693 <div class="directive-section"><h2><a name="ExtendedStatus" id="ExtendedStatus">ExtendedStatus</a> <a name="extendedstatus" id="extendedstatus">Directive</a></h2>
1694 <table class="directive">
1695 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Keep track of extended status information for each
1697 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ExtendedStatus On|Off</code></td></tr>
1698 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ExtendedStatus Off[*]</code></td></tr>
1699 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
1700 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1701 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1703 <p>This option tracks additional data per worker about the
1704 currently executing request and creates a utilization summary.
1705 You can see these variables during runtime by configuring
1706 <code class="module"><a href="../mod/mod_status.html">mod_status</a></code>. Note that other modules may
1707 rely on this scoreboard.</p>
1709 <p>This setting applies to the entire server and cannot be
1710 enabled or disabled on a virtualhost-by-virtualhost basis.
1711 The collection of extended status information can slow down
1712 the server. Also note that this setting cannot be changed
1713 during a graceful restart.</p>
1716 <p>Note that loading <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> will change
1717 the default behavior to ExtendedStatus On, while other
1718 third party modules may do the same. Such modules rely on
1719 collecting detailed information about the state of all workers.
1720 The default is changed by <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> beginning
1721 with version 2.3.6. The previous default was always Off.</p>
1726 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1727 <div class="directive-section"><h2><a name="FileETag" id="FileETag">FileETag</a> <a name="fileetag" id="fileetag">Directive</a></h2>
1728 <table class="directive">
1729 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>File attributes used to create the ETag
1730 HTTP response header for static files</td></tr>
1731 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>FileETag <var>component</var> ...</code></td></tr>
1732 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>FileETag MTime Size</code></td></tr>
1733 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1734 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1735 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1736 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1737 <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
1741 The <code class="directive">FileETag</code> directive configures the file
1742 attributes that are used to create the <code>ETag</code> (entity
1743 tag) response header field when the document is based on a static file.
1744 (The <code>ETag</code> value is used in cache management to save
1745 network bandwidth.) The
1746 <code class="directive">FileETag</code> directive allows you to choose
1747 which of these -- if any -- should be used. The recognized keywords are:
1751 <dt><strong>INode</strong></dt>
1752 <dd>The file's i-node number will be included in the calculation</dd>
1753 <dt><strong>MTime</strong></dt>
1754 <dd>The date and time the file was last modified will be included</dd>
1755 <dt><strong>Size</strong></dt>
1756 <dd>The number of bytes in the file will be included</dd>
1757 <dt><strong>All</strong></dt>
1758 <dd>All available fields will be used. This is equivalent to:
1759 <pre class="prettyprint lang-config">FileETag INode MTime Size</pre>
1761 <dt><strong>None</strong></dt>
1762 <dd>If a document is file-based, no <code>ETag</code> field will be
1763 included in the response</dd>
1766 <p>The <code>INode</code>, <code>MTime</code>, and <code>Size</code>
1767 keywords may be prefixed with either <code>+</code> or <code>-</code>,
1768 which allow changes to be made to the default setting inherited
1769 from a broader scope. Any keyword appearing without such a prefix
1770 immediately and completely cancels the inherited setting.</p>
1772 <p>If a directory's configuration includes
1773 <code>FileETag INode MTime Size</code>, and a
1774 subdirectory's includes <code>FileETag -INode</code>,
1775 the setting for that subdirectory (which will be inherited by
1776 any sub-subdirectories that don't override it) will be equivalent to
1777 <code>FileETag MTime Size</code>.</p>
1778 <div class="warning"><h3>Warning</h3>
1779 Do not change the default for directories or locations that have WebDAV
1780 enabled and use <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> as a storage provider.
1781 <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> uses <code>MTime Size</code>
1782 as a fixed format for <code>ETag</code> comparisons on conditional requests.
1783 These conditional requests will break if the <code>ETag</code> format is
1784 changed via <code class="directive">FileETag</code>.
1786 <div class="note"><h3>Server Side Includes</h3>
1787 An ETag is not generated for responses parsed by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
1788 since the response entity can change without a change of the INode, MTime, or Size
1789 of the static file with embedded SSI directives.
1794 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1795 <div class="directive-section"><h2><a name="Files" id="Files"><Files></a> <a name="files" id="files">Directive</a></h2>
1796 <table class="directive">
1797 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to matched
1799 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Files <var>filename</var>> ... </Files></code></td></tr>
1800 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1801 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1802 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1803 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1805 <p>The <code class="directive"><Files></code> directive
1806 limits the scope of the enclosed directives by filename. It is comparable
1807 to the <code class="directive"><a href="#directory"><Directory></a></code>
1808 and <code class="directive"><a href="#location"><Location></a></code>
1809 directives. It should be matched with a <code></Files></code>
1810 directive. The directives given within this section will be applied to
1811 any object with a basename (last component of filename) matching the
1812 specified filename. <code class="directive"><Files></code>
1813 sections are processed in the order they appear in the
1814 configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
1815 <code>.htaccess</code> files are read, but before <code class="directive"><a href="#location"><Location></a></code> sections. Note
1816 that <code class="directive"><Files></code> can be nested
1817 inside <code class="directive"><a href="#directory"><Directory></a></code> sections to restrict the
1818 portion of the filesystem they apply to.</p>
1820 <p>The <var>filename</var> argument should include a filename, or
1821 a wild-card string, where <code>?</code> matches any single character,
1822 and <code>*</code> matches any sequences of characters.</p>
1823 <pre class="prettyprint lang-config"><Files "cat.html">
1824 # Insert stuff that applies to cat.html here
1827 <Files "?at.*">
1828 # This would apply to cat.html, bat.html, hat.php and so on.
1829 </Files></pre>
1831 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
1832 can also be used, with the addition of the
1833 <code>~</code> character. For example:</p>
1835 <pre class="prettyprint lang-config"><Files ~ "\.(gif|jpe?g|png)$">
1837 </Files></pre>
1840 <p>would match most common Internet graphics formats. <code class="directive"><a href="#filesmatch"><FilesMatch></a></code> is preferred,
1843 <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
1844 <code>.htaccess</code> files. This allows users to control access to
1845 their own files, at a file-by-file level.</p>
1850 <li><a href="../sections.html">How <Directory>, <Location>
1851 and <Files> sections work</a> for an explanation of how these
1852 different sections are combined when a request is received</li>
1855 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1856 <div class="directive-section"><h2><a name="FilesMatch" id="FilesMatch"><FilesMatch></a> <a name="filesmatch" id="filesmatch">Directive</a></h2>
1857 <table class="directive">
1858 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to regular-expression matched
1860 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><FilesMatch <var>regex</var>> ... </FilesMatch></code></td></tr>
1861 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1862 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1863 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1864 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1866 <p>The <code class="directive"><FilesMatch></code> directive
1867 limits the scope of the enclosed directives by filename, just as the
1868 <code class="directive"><a href="#files"><Files></a></code> directive
1869 does. However, it accepts a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular
1870 expression</a>. For example:</p>
1872 <pre class="prettyprint lang-config"><FilesMatch ".+\.(gif|jpe?g|png)$">
1874 </FilesMatch></pre>
1877 <p>would match most common Internet graphics formats.</p>
1879 <div class="note">The <code>.+</code> at the start of the regex ensures that
1880 files named <code>.png</code>, or <code>.gif</code>, for example,
1881 are not matched.</div>
1883 <p>From 2.4.8 onwards, named groups and backreferences are captured and
1884 written to the environment with the corresponding name prefixed with
1885 "MATCH_" and in upper case. This allows elements of files to be referenced
1886 from within <a href="../expr.html">expressions</a> and modules like
1887 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
1888 (unnamed) backreferences are ignored. Use named groups instead.</p>
1890 <pre class="prettyprint lang-config"><FilesMatch "^(?<sitename>[^/]+)">
1891 require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
1892 </FilesMatch></pre>
1897 <li><a href="../sections.html">How <Directory>, <Location>
1898 and <Files> sections work</a> for an explanation of how these
1899 different sections are combined when a request is received</li>
1902 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1903 <div class="directive-section"><h2><a name="ForceType" id="ForceType">ForceType</a> <a name="forcetype" id="forcetype">Directive</a></h2>
1904 <table class="directive">
1905 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be served with the specified
1906 media type in the HTTP Content-Type header field</td></tr>
1907 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ForceType <var>media-type</var>|None</code></td></tr>
1908 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
1909 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1910 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1911 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1913 <p>When placed into an <code>.htaccess</code> file or a
1914 <code class="directive"><a href="#directory"><Directory></a></code>, or
1915 <code class="directive"><a href="#location"><Location></a></code> or
1916 <code class="directive"><a href="#files"><Files></a></code>
1917 section, this directive forces all matching files to be served
1918 with the content type identification given by
1919 <var>media-type</var>. For example, if you had a directory full of
1920 GIF files, but did not want to label them all with <code>.gif</code>,
1921 you might want to use:</p>
1923 <pre class="prettyprint lang-config">ForceType image/gif</pre>
1926 <p>Note that this directive overrides other indirect media type
1927 associations defined in mime.types or via the
1928 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code>.</p>
1930 <p>You can also override more general
1931 <code class="directive">ForceType</code> settings
1932 by using the value of <code>None</code>:</p>
1934 <pre class="prettyprint lang-config"># force all files to be image/gif:
1935 <Location "/images">
1939 # but normal mime-type associations here:
1940 <Location "/images/mixed">
1942 </Location></pre>
1945 <p>This directive primarily overrides the content types generated for
1946 static files served out of the filesystem. For resources other than
1947 static files, where the generator of the response typically specifies
1948 a Content-Type, this directive has no effect.</p>
1951 <div class="note"><h3>Note</h3>
1952 <p>If no handler is explicitly set for a request, the specified content
1953 type will also be used as the handler name. </p>
1955 <p>When explicit directives such as
1956 <code class="directive"><a href="#sethandler">SetHandler</a></code> or
1957 <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> do not apply
1958 to the current request, the internal handler name normally set by those
1959 directives is instead set to the content type specified by this directive.
1962 This is a historical behavior that some third-party modules
1963 (such as mod_php) may look for a "synthetic" content type used only to
1964 signal the module to take responsibility for the matching request.
1967 <p>Configurations that rely on such "synthetic" types should be avoided.
1968 Additionally, configurations that restrict access to
1969 <code class="directive"><a href="#sethandler">SetHandler</a></code> or
1970 <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> should
1971 restrict access to this directive as well.</p>
1976 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1977 <div class="directive-section"><h2><a name="GprofDir" id="GprofDir">GprofDir</a> <a name="gprofdir" id="gprofdir">Directive</a></h2>
1978 <table class="directive">
1979 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory to write gmon.out profiling data to. </td></tr>
1980 <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>
1981 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1982 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1983 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1985 <p>When the server has been compiled with gprof profiling support,
1986 <code class="directive">GprofDir</code> causes <code>gmon.out</code> files to
1987 be written to the specified directory when the process exits. If the
1988 argument ends with a percent symbol ('%'), subdirectories are created
1989 for each process id.</p>
1991 <p>This directive currently only works with the <code class="module"><a href="../mod/prefork.html">prefork</a></code>
1995 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1996 <div class="directive-section"><h2><a name="HostnameLookups" id="HostnameLookups">HostnameLookups</a> <a name="hostnamelookups" id="hostnamelookups">Directive</a></h2>
1997 <table class="directive">
1998 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables DNS lookups on client IP addresses</td></tr>
1999 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HostnameLookups On|Off|Double</code></td></tr>
2000 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HostnameLookups Off</code></td></tr>
2001 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2002 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2003 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2005 <p>This directive enables DNS lookups so that host names can be
2006 logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
2007 The value <code>Double</code> refers to doing double-reverse
2008 DNS lookup. That is, after a reverse lookup is performed, a forward
2009 lookup is then performed on that result. At least one of the IP
2010 addresses in the forward lookup must match the original
2011 address. (In "tcpwrappers" terminology this is called
2012 <code>PARANOID</code>.)</p>
2014 <p>Regardless of the setting, when <code class="module"><a href="../mod/mod_authz_host.html">mod_authz_host</a></code> is
2015 used for controlling access by hostname, a double reverse lookup
2016 will be performed. This is necessary for security. Note that the
2017 result of this double-reverse isn't generally available unless you
2018 set <code>HostnameLookups Double</code>. For example, if only
2019 <code>HostnameLookups On</code> and a request is made to an object
2020 that is protected by hostname restrictions, regardless of whether
2021 the double-reverse fails or not, CGIs will still be passed the
2022 single-reverse result in <code>REMOTE_HOST</code>.</p>
2024 <p>The default is <code>Off</code> in order to save the network
2025 traffic for those sites that don't truly need the reverse
2026 lookups done. It is also better for the end users because they
2027 don't have to suffer the extra latency that a lookup entails.
2028 Heavily loaded sites should leave this directive
2029 <code>Off</code>, since DNS lookups can take considerable
2030 amounts of time. The utility <code class="program"><a href="../programs/logresolve.html">logresolve</a></code>, compiled by
2031 default to the <code>bin</code> subdirectory of your installation
2032 directory, can be used to look up host names from logged IP addresses
2035 <p>Finally, if you have <a href="mod_authz_host.html#reqhost">hostname-based Require
2036 directives</a>, a hostname lookup will be performed regardless of
2037 the setting of <code>HostnameLookups</code>.</p>
2040 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2041 <div class="directive-section"><h2><a name="HttpProtocolOptions" id="HttpProtocolOptions">HttpProtocolOptions</a> <a name="httpprotocoloptions" id="httpprotocoloptions">Directive</a></h2>
2042 <table class="directive">
2043 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Modify restrictions on HTTP Request Messages</td></tr>
2044 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HttpProtocolOptions [Strict|Unsafe] [StrictURL|UnsafeURL]
2045 [RegisteredMethods|LenientMethods] [Allow0.9|Require1.0]</code></td></tr>
2046 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HttpProtocolOptions Strict StrictURL LenientMethods Allow0.9</code></td></tr>
2047 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2048 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2049 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2050 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.2.32 or 2.4.24 and later</td></tr>
2052 <p>This directive changes the rules applied to the HTTP Request Line
2053 (<a href="https://tools.ietf.org/html/rfc7230#section-3.1.1">RFC 7230 §3.1.1</a>) and the HTTP Request Header Fields
2054 (<a href="https://tools.ietf.org/html/rfc7230#section-3.2">RFC 7230 §3.2</a>), which are now applied by default or using
2055 the <code>Strict</code> option. Due to legacy modules, applications or
2056 custom user-agents which must be deperecated, <code>Unsafe</code>
2057 and <code>UnsafeURL</code> options have been added to revert to the legacy
2058 behaviors. These rules are applied prior to request processing, so must be
2059 configured at the global or default (first) matching virtual host section,
2060 by IP/port interface and not by name, to be honored.</p>
2062 <p>Prior to the introduction of this directive, the Apache HTTP Server
2063 request message parsers were tolerant of a number of forms of input
2064 which did not conform to the protocol.
2065 <a href="https://tools.ietf.org/html/rfc7230#section-9.4">RFC 7230 §9.4 Request Splitting</a> and
2066 <a href="https://tools.ietf.org/html/rfc7230#section-9.5">§9.5 Response Smuggling</a> call out only two of the potential
2067 risks of accepting non-conformant request messages, while
2068 <a href="https://tools.ietf.org/html/rfc7230#section-3.5">RFC 7230 §3.5</a> "Message Parsing Robustness" identify the
2069 risks of accepting obscure whitespace and request message formatting.
2070 As of the introduction of this directive, all grammer rules of the
2071 specification are enforced in the default <code>Strict</code> operating
2072 mode, and the strict whitespace suggested by section 3.5 is enforced
2073 and cannot be relaxed.</p>
2075 <p><a href="https://tools.ietf.org/html/rfc3986#section-2.2">RFC 3986 §2.2 and 2.3</a> define "Reserved Characters" and
2076 "Unreserved Characters". All other character octets are required to
2077 be %XX encoded under this spec, and RFC7230 defers to these requirements.
2078 By default the <code>StrictURI</code> option will reject all requests
2079 containing invalid characters. This rule can be relaxed with the
2080 <code>UnsafeURI</code> option to support badly written user-agents.</p>
2082 <p>Users are strongly cautioned against toggling the <code>Unsafe</code>
2083 or <code>UnsafeURI</code> modes of operation, particularly on
2084 outward-facing, publicly accessible server deployments.
2085 If an interface is required for faulty monitoring or other custom service
2086 consumers running on an intranet, users should toggle only those Unsafe
2087 options which are necessary, and only on a specific virtual host configured
2088 to service only their internal private network.</p>
2090 <p>Reviewing the messages logged to the <code class="directive">ErrorLog</code>,
2091 configured with <code class="directive">LogLevel</code> <code>debug</code> level,
2092 can help identify such faulty requests along with their origin.
2093 Users should pay particular attention to the 400 responses in the access
2094 log for invalid requests which were unexpectedly rejected.</p>
2096 <p><a href="https://tools.ietf.org/html/rfc7231#section-4.1">RFC 7231 §4.1</a> "Request Methods" "Overview" requires that
2097 origin servers shall respond with an error when an unsupported method
2098 is encountered in the request line. This already happens when the
2099 <code>LenientMethods</code> option is used, but administrators may wish
2100 to toggle the <code>RegisteredMethods</code> option and register any
2101 non-standard methods using the <code class="directive">RegisterHttpMethod</code>
2102 directive, particularly if the <code>Unsafe</code> option has been toggled.
2103 The <code>RegisteredMethods</code> option should <strong>not</strong>
2104 be toggled for forward proxy hosts, as the methods supported by the
2105 origin servers are unknown to the proxy server.</p>
2107 <p><a href="https://tools.ietf.org/html/rfc2616#section-19.6">RFC 2616 §19.6</a> "Compatibility With Previous Versions" had
2108 encouraged HTTP servers to support legacy HTTP/0.9 requests. RFC 7230
2109 superceeds this with "The expectation to support HTTP/0.9 requests has
2110 been removed" and offers additional comments in
2111 <a href="https://tools.ietf.org/html/rfc7230#appendix-A">RFC 7230 Appendix A</a>. The <code>Require1.0</code> option allows
2112 the user to remove support of the default <code>Allow0.9</code> option's
2116 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2117 <div class="directive-section"><h2><a name="If" id="If"><If></a> <a name="if" id="if">Directive</a></h2>
2118 <table class="directive">
2119 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is
2120 satisfied by a request at runtime</td></tr>
2121 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><If <var>expression</var>> ... </If></code></td></tr>
2122 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2123 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2124 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2125 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2127 <p>The <code class="directive"><If></code> directive
2128 evaluates an expression at runtime, and applies the enclosed
2129 directives if and only if the expression evaluates to true.
2132 <pre class="prettyprint lang-config"><If "-z req('Host')"></pre>
2135 <p>would match HTTP/1.0 requests without a <var>Host:</var> header.
2136 Expressions may contain various shell-like operators for string
2137 comparison (<code>==</code>, <code>!=</code>, <code><</code>, ...),
2138 integer comparison (<code>-eq</code>, <code>-ne</code>, ...),
2139 and others (<code>-n</code>, <code>-z</code>, <code>-f</code>, ...).
2140 It is also possible to use regular expressions, </p>
2142 <pre class="prettyprint lang-config"><If "%{QUERY_STRING} =~ /(delete|commit)=.*?elem/"></pre>
2145 <p>shell-like pattern matches and many other operations. These operations
2146 can be done on request headers (<code>req</code>), environment variables
2147 (<code>env</code>), and a large number of other properties. The full
2148 documentation is available in <a href="../expr.html">Expressions in
2149 Apache HTTP Server</a>.</p>
2151 <p>Only directives that support the <a href="directive-dict.html#Context">directory context</a> can be used within this configuration section.</p>
2153 <div class="warning">
2154 Certain variables, such as <code>CONTENT_TYPE</code> and other
2155 response headers, are set after <If> conditions have already
2156 been evaluated, and so will not be available to use in this
2163 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
2164 for a complete reference and more examples.</li>
2165 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
2166 <li><code class="directive"><a href="#else"><Else></a></code></li>
2167 <li><a href="../sections.html">How <Directory>, <Location>,
2168 <Files> sections work</a> for an explanation of how these
2169 different sections are combined when a request is received.
2170 <code class="directive"><If></code>,
2171 <code class="directive"><ElseIf></code>, and
2172 <code class="directive"><Else></code> are applied last.</li>
2175 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2176 <div class="directive-section"><h2><a name="IfDefine" id="IfDefine"><IfDefine></a> <a name="ifdefine" id="ifdefine">Directive</a></h2>
2177 <table class="directive">
2178 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that will be processed only
2179 if a test is true at startup</td></tr>
2180 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfDefine [!]<var>parameter-name</var>> ...
2181 </IfDefine></code></td></tr>
2182 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2183 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2184 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2185 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2187 <p>The <code><IfDefine <var>test</var>>...</IfDefine>
2188 </code> section is used to mark directives that are conditional. The
2189 directives within an <code class="directive"><IfDefine></code>
2190 section are only processed if the <var>test</var> is true. If <var>
2191 test</var> is false, everything between the start and end markers is
2194 <p>The <var>test</var> in the <code class="directive"><IfDefine></code> section directive can be one of two forms:</p>
2197 <li><var>parameter-name</var></li>
2199 <li><code>!</code><var>parameter-name</var></li>
2202 <p>In the former case, the directives between the start and end
2203 markers are only processed if the parameter named
2204 <var>parameter-name</var> is defined. The second format reverses
2205 the test, and only processes the directives if
2206 <var>parameter-name</var> is <strong>not</strong> defined.</p>
2208 <p>The <var>parameter-name</var> argument is a define as given on the
2209 <code class="program"><a href="../programs/httpd.html">httpd</a></code> command line via <code>-D<var>parameter</var>
2210 </code> at the time the server was started or by the <code class="directive"><a href="#define">Define</a></code> directive.</p>
2212 <p><code class="directive"><IfDefine></code> sections are
2213 nest-able, which can be used to implement simple
2214 multiple-parameter tests. Example:</p>
2216 <div class="example"><p><code>httpd -DReverseProxy -DUseCache -DMemCache ...</code></p></div>
2217 <pre class="prettyprint lang-config"><IfDefine ReverseProxy>
2218 LoadModule proxy_module modules/mod_proxy.so
2219 LoadModule proxy_http_module modules/mod_proxy_http.so
2220 <IfDefine UseCache>
2221 LoadModule cache_module modules/mod_cache.so
2222 <IfDefine MemCache>
2223 LoadModule mem_cache_module modules/mod_mem_cache.so
2225 <IfDefine !MemCache>
2226 LoadModule cache_disk_module modules/mod_cache_disk.so
2229 </IfDefine></pre>
2233 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2234 <div class="directive-section"><h2><a name="IfModule" id="IfModule"><IfModule></a> <a name="ifmodule" id="ifmodule">Directive</a></h2>
2235 <table class="directive">
2236 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that are processed conditional on the
2237 presence or absence of a specific module</td></tr>
2238 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfModule [!]<var>module-file</var>|<var>module-identifier</var>> ...
2239 </IfModule></code></td></tr>
2240 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2241 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2242 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2243 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2245 <p>The <code><IfModule <var>test</var>>...</IfModule></code>
2246 section is used to mark directives that are conditional on the presence of
2247 a specific module. The directives within an <code class="directive"><IfModule></code> section are only processed if the <var>test</var>
2248 is true. If <var>test</var> is false, everything between the start and
2249 end markers is ignored.</p>
2251 <p>The <var>test</var> in the <code class="directive"><IfModule></code> section directive can be one of two forms:</p>
2254 <li><var>module</var></li>
2256 <li>!<var>module</var></li>
2259 <p>In the former case, the directives between the start and end
2260 markers are only processed if the module named <var>module</var>
2261 is included in Apache httpd -- either compiled in or
2262 dynamically loaded using <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code>. The second format reverses the test,
2263 and only processes the directives if <var>module</var> is
2264 <strong>not</strong> included.</p>
2266 <p>The <var>module</var> argument can be either the module identifier or
2267 the file name of the module, at the time it was compiled. For example,
2268 <code>rewrite_module</code> is the identifier and
2269 <code>mod_rewrite.c</code> is the file name. If a module consists of
2270 several source files, use the name of the file containing the string
2271 <code>STANDARD20_MODULE_STUFF</code>.</p>
2273 <p><code class="directive"><IfModule></code> sections are
2274 nest-able, which can be used to implement simple multiple-module
2277 <div class="note">This section should only be used if you need to have one
2278 configuration file that works whether or not a specific module
2279 is available. In normal operation, directives need not be
2280 placed in <code class="directive"><IfModule></code>
2284 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2285 <div class="directive-section"><h2><a name="Include" id="Include">Include</a> <a name="include" id="include">Directive</a></h2>
2286 <table class="directive">
2287 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2288 the server configuration files</td></tr>
2289 <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>
2290 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2291 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2292 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2293 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directory
2294 wildcard matching available in 2.3.6 and later</td></tr>
2296 <p>This directive allows inclusion of other configuration files
2297 from within the server configuration files.</p>
2299 <p>Shell-style (<code>fnmatch()</code>) wildcard characters can be used
2300 in the filename or directory parts of the path to include several files
2301 at once, in alphabetical order. In addition, if
2302 <code class="directive">Include</code> points to a directory, rather than a file,
2303 Apache httpd will read all files in that directory and any subdirectory.
2304 However, including entire directories is not recommended, because it is
2305 easy to accidentally leave temporary files in a directory that can cause
2306 <code class="program"><a href="../programs/httpd.html">httpd</a></code> to fail. Instead, we encourage you to use the
2307 wildcard syntax shown below, to include files that match a particular
2308 pattern, such as *.conf, for example.</p>
2310 <p>The <code class="directive"><a href="#include">Include</a></code> directive will
2311 <strong>fail with an error</strong> if a wildcard expression does not
2312 match any file. The <code class="directive"><a href="#includeoptional">IncludeOptional</a></code>
2313 directive can be used if non-matching wildcards should be ignored.</p>
2315 <p>The file path specified may be an absolute path, or may be relative
2316 to the <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory.</p>
2320 <pre class="prettyprint lang-config">Include /usr/local/apache2/conf/ssl.conf
2321 Include /usr/local/apache2/conf/vhosts/*.conf</pre>
2324 <p>Or, providing paths relative to your <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory:</p>
2326 <pre class="prettyprint lang-config">Include conf/ssl.conf
2327 Include conf/vhosts/*.conf</pre>
2330 <p>Wildcards may be included in the directory or file portion of the
2331 path. This example will fail if there is no subdirectory in conf/vhosts
2332 that contains at least one *.conf file:</p>
2334 <pre class="prettyprint lang-config">Include conf/vhosts/*/*.conf</pre>
2337 <p>Alternatively, the following command will just be ignored in case of
2338 missing files or directories:</p>
2340 <pre class="prettyprint lang-config">IncludeOptional conf/vhosts/*/*.conf</pre>
2346 <li><code class="directive"><a href="#includeoptional">IncludeOptional</a></code></li>
2347 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
2350 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2351 <div class="directive-section"><h2><a name="IncludeOptional" id="IncludeOptional">IncludeOptional</a> <a name="includeoptional" id="includeoptional">Directive</a></h2>
2352 <table class="directive">
2353 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2354 the server configuration files</td></tr>
2355 <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>
2356 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2357 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2358 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2359 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in 2.3.6 and later</td></tr>
2361 <p>This directive allows inclusion of other configuration files
2362 from within the server configuration files. It works identically to the
2363 <code class="directive"><a href="#include">Include</a></code> directive, with the
2364 exception that if wildcards do not match any file or directory, the
2365 <code class="directive"><a href="#includeoptional">IncludeOptional</a></code> directive will be
2366 silently ignored instead of causing an error.</p>
2370 <li><code class="directive"><a href="#include">Include</a></code></li>
2371 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
2374 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2375 <div class="directive-section"><h2><a name="KeepAlive" id="KeepAlive">KeepAlive</a> <a name="keepalive" id="keepalive">Directive</a></h2>
2376 <table class="directive">
2377 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables HTTP persistent connections</td></tr>
2378 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAlive On|Off</code></td></tr>
2379 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAlive On</code></td></tr>
2380 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2381 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2382 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2384 <p>The Keep-Alive extension to HTTP/1.0 and the persistent
2385 connection feature of HTTP/1.1 provide long-lived HTTP sessions
2386 which allow multiple requests to be sent over the same TCP
2387 connection. In some cases this has been shown to result in an
2388 almost 50% speedup in latency times for HTML documents with
2389 many images. To enable Keep-Alive connections, set
2390 <code>KeepAlive On</code>.</p>
2392 <p>For HTTP/1.0 clients, Keep-Alive connections will only be
2393 used if they are specifically requested by a client. In
2394 addition, a Keep-Alive connection with an HTTP/1.0 client can
2395 only be used when the length of the content is known in
2396 advance. This implies that dynamic content such as CGI output,
2397 SSI pages, and server-generated directory listings will
2398 generally not use Keep-Alive connections to HTTP/1.0 clients.
2399 For HTTP/1.1 clients, persistent connections are the default
2400 unless otherwise specified. If the client requests it, chunked
2401 encoding will be used in order to send content of unknown
2402 length over persistent connections.</p>
2404 <p>When a client uses a Keep-Alive connection, it will be counted
2405 as a single "request" for the <code class="directive"><a href="../mod/mpm_common.html#maxconnectionsperchild">MaxConnectionsPerChild</a></code> directive, regardless
2406 of how many requests are sent using the connection.</p>
2410 <li><code class="directive"><a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></code></li>
2413 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2414 <div class="directive-section"><h2><a name="KeepAliveTimeout" id="KeepAliveTimeout">KeepAliveTimeout</a> <a name="keepalivetimeout" id="keepalivetimeout">Directive</a></h2>
2415 <table class="directive">
2416 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for subsequent
2417 requests on a persistent connection</td></tr>
2418 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAliveTimeout <var>num</var>[ms]</code></td></tr>
2419 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAliveTimeout 5</code></td></tr>
2420 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2421 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2422 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2424 <p>The number of seconds Apache httpd will wait for a subsequent
2425 request before closing the connection. By adding a postfix of ms the
2426 timeout can be also set in milliseconds. Once a request has been
2427 received, the timeout value specified by the
2428 <code class="directive"><a href="#timeout">Timeout</a></code> directive applies.</p>
2430 <p>Setting <code class="directive">KeepAliveTimeout</code> to a high value
2431 may cause performance problems in heavily loaded servers. The
2432 higher the timeout, the more server processes will be kept
2433 occupied waiting on connections with idle clients.</p>
2435 <p>If <code class="directive">KeepAliveTimeout</code> is <strong>not</strong>
2436 set for a name-based virtual host, the value of the first defined
2437 virtual host best matching the local IP and port will be used.</p>
2440 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2441 <div class="directive-section"><h2><a name="Limit" id="Limit"><Limit></a> <a name="limit" id="limit">Directive</a></h2>
2442 <table class="directive">
2443 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict enclosed access controls to only certain HTTP
2445 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Limit <var>method</var> [<var>method</var>] ... > ...
2446 </Limit></code></td></tr>
2447 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2448 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2449 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2450 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2452 <p>Access controls are normally effective for
2453 <strong>all</strong> access methods, and this is the usual
2454 desired behavior. <strong>In the general case, access control
2455 directives should not be placed within a
2456 <code class="directive"><Limit></code> section.</strong></p>
2458 <p>The purpose of the <code class="directive"><Limit></code>
2459 directive is to restrict the effect of the access controls to the
2460 nominated HTTP methods. For all other methods, the access
2461 restrictions that are enclosed in the <code class="directive"><Limit></code> bracket <strong>will have no
2462 effect</strong>. The following example applies the access control
2463 only to the methods <code>POST</code>, <code>PUT</code>, and
2464 <code>DELETE</code>, leaving all other methods unprotected:</p>
2466 <pre class="prettyprint lang-config"><Limit POST PUT DELETE>
2468 </Limit></pre>
2471 <p>The method names listed can be one or more of: <code>GET</code>,
2472 <code>POST</code>, <code>PUT</code>, <code>DELETE</code>,
2473 <code>CONNECT</code>, <code>OPTIONS</code>,
2474 <code>PATCH</code>, <code>PROPFIND</code>, <code>PROPPATCH</code>,
2475 <code>MKCOL</code>, <code>COPY</code>, <code>MOVE</code>,
2476 <code>LOCK</code>, and <code>UNLOCK</code>. <strong>The method name is
2477 case-sensitive.</strong> If <code>GET</code> is used, it will also
2478 restrict <code>HEAD</code> requests. The <code>TRACE</code> method
2479 cannot be limited (see <code class="directive"><a href="#traceenable">TraceEnable</a></code>).</p>
2481 <div class="warning">A <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section should always be
2482 used in preference to a <code class="directive"><Limit></code>
2483 section when restricting access, since a <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section provides protection
2484 against arbitrary methods.</div>
2486 <p>The <code class="directive"><Limit></code> and
2487 <code class="directive"><a href="#limitexcept"><LimitExcept></a></code>
2488 directives may be nested. In this case, each successive level of
2489 <code class="directive"><Limit></code> or <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> directives must
2490 further restrict the set of methods to which access controls apply.</p>
2492 <div class="warning">When using
2493 <code class="directive"><Limit></code> or
2494 <code class="directive"><LimitExcept></code> directives with
2495 the <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directive,
2496 note that the first <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code>
2497 to succeed authorizes the request, regardless of the presence of other
2498 <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directives.</div>
2500 <p>For example, given the following configuration, all users will
2501 be authorized for <code>POST</code> requests, and the
2502 <code>Require group editors</code> directive will be ignored
2505 <pre class="prettyprint lang-config"><LimitExcept GET>
2507 </LimitExcept>
2509 Require group editors
2510 </Limit></pre>
2514 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2515 <div class="directive-section"><h2><a name="LimitExcept" id="LimitExcept"><LimitExcept></a> <a name="limitexcept" id="limitexcept">Directive</a></h2>
2516 <table class="directive">
2517 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict access controls to all HTTP methods
2518 except the named ones</td></tr>
2519 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LimitExcept <var>method</var> [<var>method</var>] ... > ...
2520 </LimitExcept></code></td></tr>
2521 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2522 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2523 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2524 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2526 <p><code class="directive"><LimitExcept></code> and
2527 <code></LimitExcept></code> are used to enclose
2528 a group of access control directives which will then apply to any
2529 HTTP access method <strong>not</strong> listed in the arguments;
2530 i.e., it is the opposite of a <code class="directive"><a href="#limit"><Limit></a></code> section and can be used to control
2531 both standard and nonstandard/unrecognized methods. See the
2532 documentation for <code class="directive"><a href="#limit"><Limit></a></code> for more details.</p>
2536 <pre class="prettyprint lang-config"><LimitExcept POST GET>
2538 </LimitExcept></pre>
2543 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2544 <div class="directive-section"><h2><a name="LimitInternalRecursion" id="LimitInternalRecursion">LimitInternalRecursion</a> <a name="limitinternalrecursion" id="limitinternalrecursion">Directive</a></h2>
2545 <table class="directive">
2546 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine maximum number of internal redirects and nested
2547 subrequests</td></tr>
2548 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitInternalRecursion <var>number</var> [<var>number</var>]</code></td></tr>
2549 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitInternalRecursion 10</code></td></tr>
2550 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2551 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2552 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2554 <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
2555 redirects the original request to a CGI script. A subrequest is Apache httpd's
2556 mechanism to find out what would happen for some URI if it were requested.
2557 For example, <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> uses subrequests to look for the
2558 files listed in the <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
2561 <p><code class="directive">LimitInternalRecursion</code> prevents the server
2562 from crashing when entering an infinite loop of internal redirects or
2563 subrequests. Such loops are usually caused by misconfigurations.</p>
2565 <p>The directive stores two different limits, which are evaluated on
2566 per-request basis. The first <var>number</var> is the maximum number of
2567 internal redirects that may follow each other. The second <var>number</var>
2568 determines how deeply subrequests may be nested. If you specify only one
2569 <var>number</var>, it will be assigned to both limits.</p>
2571 <pre class="prettyprint lang-config">LimitInternalRecursion 5</pre>
2575 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2576 <div class="directive-section"><h2><a name="LimitRequestBody" id="LimitRequestBody">LimitRequestBody</a> <a name="limitrequestbody" id="limitrequestbody">Directive</a></h2>
2577 <table class="directive">
2578 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restricts the total size of the HTTP request body sent
2579 from the client</td></tr>
2580 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestBody <var>bytes</var></code></td></tr>
2581 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestBody 0</code></td></tr>
2582 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2583 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2584 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2585 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2587 <p>This directive specifies the number of <var>bytes</var> from 0
2588 (meaning unlimited) to 2147483647 (2GB) that are allowed in a
2589 request body. See the note below for the limited applicability
2590 to proxy requests.</p>
2592 <p>The <code class="directive">LimitRequestBody</code> directive allows
2593 the user to set a limit on the allowed size of an HTTP request
2594 message body within the context in which the directive is given
2595 (server, per-directory, per-file or per-location). If the client
2596 request exceeds that limit, the server will return an error
2597 response instead of servicing the request. The size of a normal
2598 request message body will vary greatly depending on the nature of
2599 the resource and the methods allowed on that resource. CGI scripts
2600 typically use the message body for retrieving form information.
2601 Implementations of the <code>PUT</code> method will require
2602 a value at least as large as any representation that the server
2603 wishes to accept for that resource.</p>
2605 <p>This directive gives the server administrator greater
2606 control over abnormal client request behavior, which may be
2607 useful for avoiding some forms of denial-of-service
2610 <p>If, for example, you are permitting file upload to a particular
2611 location and wish to limit the size of the uploaded file to 100K,
2612 you might use the following directive:</p>
2614 <pre class="prettyprint lang-config">LimitRequestBody 102400</pre>
2617 <div class="note"><p>For a full description of how this directive is interpreted by
2618 proxy requests, see the <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> documentation.</p>
2623 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2624 <div class="directive-section"><h2><a name="LimitRequestFields" id="LimitRequestFields">LimitRequestFields</a> <a name="limitrequestfields" id="limitrequestfields">Directive</a></h2>
2625 <table class="directive">
2626 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of HTTP request header fields that
2627 will be accepted from the client</td></tr>
2628 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFields <var>number</var></code></td></tr>
2629 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFields 100</code></td></tr>
2630 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2631 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2632 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2634 <p><var>Number</var> is an integer from 0 (meaning unlimited) to
2635 32767. The default value is defined by the compile-time
2636 constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
2639 <p>The <code class="directive">LimitRequestFields</code> directive allows
2640 the server administrator to modify the limit on the number of
2641 request header fields allowed in an HTTP request. A server needs
2642 this value to be larger than the number of fields that a normal
2643 client request might include. The number of request header fields
2644 used by a client rarely exceeds 20, but this may vary among
2645 different client implementations, often depending upon the extent
2646 to which a user has configured their browser to support detailed
2647 content negotiation. Optional HTTP extensions are often expressed
2648 using request header fields.</p>
2650 <p>This directive gives the server administrator greater
2651 control over abnormal client request behavior, which may be
2652 useful for avoiding some forms of denial-of-service attacks.
2653 The value should be increased if normal clients see an error
2654 response from the server that indicates too many fields were
2655 sent in the request.</p>
2659 <pre class="prettyprint lang-config">LimitRequestFields 50</pre>
2662 <div class="warning"><h3>Warning</h3>
2663 <p> When name-based virtual hosting is used, the value for this
2664 directive is taken from the default (first-listed) virtual host for the
2665 local IP and port combination.</p>
2670 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2671 <div class="directive-section"><h2><a name="LimitRequestFieldSize" id="LimitRequestFieldSize">LimitRequestFieldSize</a> <a name="limitrequestfieldsize" id="limitrequestfieldsize">Directive</a></h2>
2672 <table class="directive">
2673 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of the HTTP request header allowed from the
2675 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFieldSize <var>bytes</var></code></td></tr>
2676 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFieldSize 8190</code></td></tr>
2677 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2678 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2679 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2681 <p>This directive specifies the number of <var>bytes</var>
2682 that will be allowed in an HTTP request header.</p>
2684 <p>The <code class="directive">LimitRequestFieldSize</code> directive
2685 allows the server administrator to set the limit
2686 on the allowed size of an HTTP request header field. A server
2687 needs this value to be large enough to hold any one header field
2688 from a normal client request. The size of a normal request header
2689 field will vary greatly among different client implementations,
2690 often depending upon the extent to which a user has configured
2691 their browser to support detailed content negotiation. SPNEGO
2692 authentication headers can be up to 12392 bytes.</p>
2694 <p>This directive gives the server administrator greater
2695 control over abnormal client request behavior, which may be
2696 useful for avoiding some forms of denial-of-service attacks.</p>
2700 <pre class="prettyprint lang-config">LimitRequestFieldSize 4094</pre>
2703 <div class="note">Under normal conditions, the value should not be changed from
2706 <div class="warning"><h3>Warning</h3>
2707 <p> When name-based virtual hosting is used, the value for this
2708 directive is taken from the default (first-listed) virtual host best
2709 matching the current IP address and port combination.</p>
2713 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2714 <div class="directive-section"><h2><a name="LimitRequestLine" id="LimitRequestLine">LimitRequestLine</a> <a name="limitrequestline" id="limitrequestline">Directive</a></h2>
2715 <table class="directive">
2716 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limit the size of the HTTP request line that will be accepted
2717 from the client</td></tr>
2718 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestLine <var>bytes</var></code></td></tr>
2719 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestLine 8190</code></td></tr>
2720 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2721 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2722 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2724 <p>This directive sets the number of <var>bytes</var> that will be
2725 allowed on the HTTP request-line.</p>
2727 <p>The <code class="directive">LimitRequestLine</code> directive allows
2728 the server administrator to set the limit on the allowed size
2729 of a client's HTTP request-line. Since the request-line consists of the
2730 HTTP method, URI, and protocol version, the
2731 <code class="directive">LimitRequestLine</code> directive places a
2732 restriction on the length of a request-URI allowed for a request
2733 on the server. A server needs this value to be large enough to
2734 hold any of its resource names, including any information that
2735 might be passed in the query part of a <code>GET</code> request.</p>
2737 <p>This directive gives the server administrator greater
2738 control over abnormal client request behavior, which may be
2739 useful for avoiding some forms of denial-of-service attacks.</p>
2743 <pre class="prettyprint lang-config">LimitRequestLine 4094</pre>
2746 <div class="note">Under normal conditions, the value should not be changed from
2749 <div class="warning"><h3>Warning</h3>
2750 <p> When name-based virtual hosting is used, the value for this
2751 directive is taken from the default (first-listed) virtual host best
2752 matching the current IP address and port combination.</p>
2757 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2758 <div class="directive-section"><h2><a name="LimitXMLRequestBody" id="LimitXMLRequestBody">LimitXMLRequestBody</a> <a name="limitxmlrequestbody" id="limitxmlrequestbody">Directive</a></h2>
2759 <table class="directive">
2760 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of an XML-based request body</td></tr>
2761 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitXMLRequestBody <var>bytes</var></code></td></tr>
2762 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitXMLRequestBody 1000000</code></td></tr>
2763 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2764 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2765 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2766 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2768 <p>Limit (in bytes) on maximum size of an XML-based request
2769 body. A value of <code>0</code> will disable any checking.</p>
2773 <pre class="prettyprint lang-config">LimitXMLRequestBody 0</pre>
2778 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2779 <div class="directive-section"><h2><a name="Location" id="Location"><Location></a> <a name="location" id="location">Directive</a></h2>
2780 <table class="directive">
2781 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to matching
2783 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Location
2784 <var>URL-path</var>|<var>URL</var>> ... </Location></code></td></tr>
2785 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2786 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2787 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2789 <p>The <code class="directive"><Location></code> directive
2790 limits the scope of the enclosed directives by URL. It is similar to the
2791 <code class="directive"><a href="#directory"><Directory></a></code>
2792 directive, and starts a subsection which is terminated with a
2793 <code></Location></code> directive. <code class="directive"><Location></code> sections are processed in the
2794 order they appear in the configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
2795 <code>.htaccess</code> files are read, and after the <code class="directive"><a href="#files"><Files></a></code> sections.</p>
2797 <p><code class="directive"><Location></code> sections operate
2798 completely outside the filesystem. This has several consequences.
2799 Most importantly, <code class="directive"><Location></code>
2800 directives should not be used to control access to filesystem
2801 locations. Since several different URLs may map to the same
2802 filesystem location, such access controls may by circumvented.</p>
2804 <p>The enclosed directives will be applied to the request if the path component
2805 of the URL meets <em>any</em> of the following criteria:
2808 <li>The specified location matches exactly the path component of the URL.
2810 <li>The specified location, which ends in a forward slash, is a prefix
2811 of the path component of the URL (treated as a context root).
2813 <li>The specified location, with the addition of a trailing slash, is a
2814 prefix of the path component of the URL (also treated as a context root).
2818 In the example below, where no trailing slash is used, requests to
2819 /private1, /private1/ and /private1/file.txt will have the enclosed
2820 directives applied, but /private1other would not.
2822 <pre class="prettyprint lang-config"><Location "/private1">
2824 </Location></pre>
2827 In the example below, where a trailing slash is used, requests to
2828 /private2/ and /private2/file.txt will have the enclosed
2829 directives applied, but /private2 and /private2other would not.
2831 <pre class="prettyprint lang-config"><Location "/private2<em>/</em>">
2833 </Location></pre>
2836 <div class="note"><h3>When to use <code class="directive"><Location></code></h3>
2838 <p>Use <code class="directive"><Location></code> to apply
2839 directives to content that lives outside the filesystem. For
2840 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
2841 <code><Location "/"></code>, which is an easy way to
2842 apply a configuration to the entire server.</p>
2845 <p>For all origin (non-proxy) requests, the URL to be matched is a
2846 URL-path of the form <code>/path/</code>. <em>No scheme, hostname,
2847 port, or query string may be included.</em> For proxy requests, the
2848 URL to be matched is of the form
2849 <code>scheme://servername/path</code>, and you must include the
2852 <p>The URL may use wildcards. In a wild-card string, <code>?</code> matches
2853 any single character, and <code>*</code> matches any sequences of
2854 characters. Neither wildcard character matches a / in the URL-path.</p>
2856 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
2857 can also be used, with the addition of the <code>~</code>
2858 character. For example:</p>
2860 <pre class="prettyprint lang-config"><Location ~ "/(extra|special)/data">
2862 </Location></pre>
2865 <p>would match URLs that contained the substring <code>/extra/data</code>
2866 or <code>/special/data</code>. The directive <code class="directive"><a href="#locationmatch"><LocationMatch></a></code> behaves
2867 identical to the regex version of <code class="directive"><Location></code>, and is preferred, for the
2868 simple reason that <code>~</code> is hard to distinguish from
2869 <code>-</code> in many fonts.</p>
2871 <p>The <code class="directive"><Location></code>
2872 functionality is especially useful when combined with the
2873 <code class="directive"><a href="#sethandler">SetHandler</a></code>
2874 directive. For example, to enable status requests but allow them
2875 only from browsers at <code>example.com</code>, you might use:</p>
2877 <pre class="prettyprint lang-config"><Location "/status">
2878 SetHandler server-status
2879 Require host example.com
2880 </Location></pre>
2883 <div class="note"><h3>Note about / (slash)</h3>
2884 <p>The slash character has special meaning depending on where in a
2885 URL it appears. People may be used to its behavior in the filesystem
2886 where multiple adjacent slashes are frequently collapsed to a single
2887 slash (<em>i.e.</em>, <code>/home///foo</code> is the same as
2888 <code>/home/foo</code>). In URL-space this is not necessarily true.
2889 The <code class="directive"><a href="#locationmatch"><LocationMatch></a></code>
2890 directive and the regex version of <code class="directive"><Location></code> require you to explicitly specify multiple
2891 slashes if that is your intention.</p>
2893 <p>For example, <code><LocationMatch "^/abc"></code> would match
2894 the request URL <code>/abc</code> but not the request URL <code>
2895 //abc</code>. The (non-regex) <code class="directive"><Location></code> directive behaves similarly when used for
2896 proxy requests. But when (non-regex) <code class="directive"><Location></code> is used for non-proxy requests it will
2897 implicitly match multiple slashes with a single slash. For example,
2898 if you specify <code><Location "/abc/def"></code> and the
2899 request is to <code>/abc//def</code> then it will match.</p>
2904 <li><a href="../sections.html">How <Directory>, <Location>
2905 and <Files> sections work</a> for an explanation of how these
2906 different sections are combined when a request is received.</li>
2907 <li><code class="directive"><a href="#locationmatch">LocationMatch</a></code></li>
2910 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2911 <div class="directive-section"><h2><a name="LocationMatch" id="LocationMatch"><LocationMatch></a> <a name="locationmatch" id="locationmatch">Directive</a></h2>
2912 <table class="directive">
2913 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to regular-expression
2914 matching URLs</td></tr>
2915 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LocationMatch
2916 <var>regex</var>> ... </LocationMatch></code></td></tr>
2917 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2918 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2919 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2921 <p>The <code class="directive"><LocationMatch></code> directive
2922 limits the scope of the enclosed directives by URL, in an identical manner
2923 to <code class="directive"><a href="#location"><Location></a></code>. However,
2924 it takes a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>
2925 as an argument instead of a simple string. For example:</p>
2927 <pre class="prettyprint lang-config"><LocationMatch "/(extra|special)/data">
2929 </LocationMatch></pre>
2932 <p>would match URLs that contained the substring <code>/extra/data</code>
2933 or <code>/special/data</code>.</p>
2935 <div class="note"><p>If the intent is that a URL <strong>starts with</strong>
2936 <code>/extra/data</code>, rather than merely
2937 <strong>contains</strong> <code>/extra/data</code>, prefix the
2938 regular expression with a <code>^</code> to require this.</p>
2940 <pre class="prettyprint lang-config"><LocationMatch "^/(extra|special)/data"></pre>
2944 <p>From 2.4.8 onwards, named groups and backreferences are captured and
2945 written to the environment with the corresponding name prefixed with
2946 "MATCH_" and in upper case. This allows elements of URLs to be referenced
2947 from within <a href="../expr.html">expressions</a> and modules like
2948 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
2949 (unnamed) backreferences are ignored. Use named groups instead.</p>
2951 <pre class="prettyprint lang-config"><LocationMatch "^/combined/(?<sitename>[^/]+)">
2952 require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
2953 </LocationMatch></pre>
2958 <li><a href="../sections.html">How <Directory>, <Location>
2959 and <Files> sections work</a> for an explanation of how these
2960 different sections are combined when a request is received</li>
2963 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2964 <div class="directive-section"><h2><a name="LogLevel" id="LogLevel">LogLevel</a> <a name="loglevel" id="loglevel">Directive</a></h2>
2965 <table class="directive">
2966 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls the verbosity of the ErrorLog</td></tr>
2967 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel [<var>module</var>:]<var>level</var>
2968 [<var>module</var>:<var>level</var>] ...
2970 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LogLevel warn</code></td></tr>
2971 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2972 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2973 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2974 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Per-module and per-directory configuration is available in
2975 Apache HTTP Server 2.3.6 and later</td></tr>
2977 <p><code class="directive">LogLevel</code> adjusts the verbosity of the
2978 messages recorded in the error logs (see <code class="directive"><a href="#errorlog">ErrorLog</a></code> directive). The following
2979 <var>level</var>s are available, in order of decreasing
2982 <table class="bordered">
2985 <th><strong>Level</strong> </th>
2987 <th><strong>Description</strong> </th>
2989 <th><strong>Example</strong> </th>
2993 <td><code>emerg</code> </td>
2995 <td>Emergencies - system is unusable.</td>
2997 <td>"Child cannot open lock file. Exiting"</td>
3001 <td><code>alert</code> </td>
3003 <td>Action must be taken immediately.</td>
3005 <td>"getpwuid: couldn't determine user name from uid"</td>
3009 <td><code>crit</code> </td>
3011 <td>Critical Conditions.</td>
3013 <td>"socket: Failed to get a socket, exiting child"</td>
3017 <td><code>error</code> </td>
3019 <td>Error conditions.</td>
3021 <td>"Premature end of script headers"</td>
3025 <td><code>warn</code> </td>
3027 <td>Warning conditions.</td>
3029 <td>"child process 1234 did not exit, sending another
3034 <td><code>notice</code> </td>
3036 <td>Normal but significant condition.</td>
3038 <td>"httpd: caught SIGBUS, attempting to dump core in
3043 <td><code>info</code> </td>
3045 <td>Informational.</td>
3047 <td>"Server seems busy, (you may need to increase
3048 StartServers, or Min/MaxSpareServers)..."</td>
3052 <td><code>debug</code> </td>
3054 <td>Debug-level messages</td>
3056 <td>"Opening config file ..."</td>
3059 <td><code>trace1</code> </td>
3061 <td>Trace messages</td>
3063 <td>"proxy: FTP: control connection complete"</td>
3066 <td><code>trace2</code> </td>
3068 <td>Trace messages</td>
3070 <td>"proxy: CONNECT: sending the CONNECT request to the remote proxy"</td>
3073 <td><code>trace3</code> </td>
3075 <td>Trace messages</td>
3077 <td>"openssl: Handshake: start"</td>
3080 <td><code>trace4</code> </td>
3082 <td>Trace messages</td>
3084 <td>"read from buffered SSL brigade, mode 0, 17 bytes"</td>
3087 <td><code>trace5</code> </td>
3089 <td>Trace messages</td>
3091 <td>"map lookup FAILED: map=rewritemap key=keyname"</td>
3094 <td><code>trace6</code> </td>
3096 <td>Trace messages</td>
3098 <td>"cache lookup FAILED, forcing new map lookup"</td>
3101 <td><code>trace7</code> </td>
3103 <td>Trace messages, dumping large amounts of data</td>
3105 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3108 <td><code>trace8</code> </td>
3110 <td>Trace messages, dumping large amounts of data</td>
3112 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3116 <p>When a particular level is specified, messages from all
3117 other levels of higher significance will be reported as well.
3118 <em>E.g.</em>, when <code>LogLevel info</code> is specified,
3119 then messages with log levels of <code>notice</code> and
3120 <code>warn</code> will also be posted.</p>
3122 <p>Using a level of at least <code>crit</code> is
3127 <pre class="prettyprint lang-config">LogLevel notice</pre>
3130 <div class="note"><h3>Note</h3>
3131 <p>When logging to a regular file, messages of the level
3132 <code>notice</code> cannot be suppressed and thus are always
3133 logged. However, this doesn't apply when logging is done
3134 using <code>syslog</code>.</p>
3137 <p>Specifying a level without a module name will reset the level
3138 for all modules to that level. Specifying a level with a module
3139 name will set the level for that module only. It is possible to
3140 use the module source file name, the module identifier, or the
3141 module identifier with the trailing <code>_module</code> omitted
3142 as module specification. This means the following three specifications
3145 <pre class="prettyprint lang-config">LogLevel info ssl:warn
3146 LogLevel info mod_ssl.c:warn
3147 LogLevel info ssl_module:warn</pre>
3150 <p>It is also possible to change the level per directory:</p>
3152 <pre class="prettyprint lang-config">LogLevel info
3153 <Directory "/usr/local/apache/htdocs/app">
3155 </Directory></pre>
3159 Per directory loglevel configuration only affects messages that are
3160 logged after the request has been parsed and that are associated with
3161 the request. Log messages which are associated with the server or
3162 the connection are not affected. The latter can be influenced by the
3163 <code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code> directive,
3169 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
3170 <li><code class="directive"><a href="#errorlogformat">ErrorLogFormat</a></code></li>
3171 <li><code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code></li>
3172 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
3175 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3176 <div class="directive-section"><h2><a name="LogLevelOverride" id="LogLevelOverride">LogLevelOverride</a> <a name="logleveloverride" id="logleveloverride">Directive</a></h2>
3177 <table class="directive">
3178 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Override the verbosity of the ErrorLog for certain clients</td></tr>
3179 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel <var>ipaddress</var>[/<var>prefixlen</var>]
3180 [<var>module</var>:]<var>level</var> [<var>module</var>:<var>level</var>] ...
3182 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>unset</code></td></tr>
3183 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3184 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3185 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3186 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.5.0 and later</td></tr>
3188 <p><code class="directive">LogLevelOverride</code> adjusts the
3189 <code class="directive"><a href="#loglevel">LogLevel</a></code> for requests coming from
3190 certain client IP addresses.
3191 This allows to enable verbose logging only for certain test clients.
3192 The IP address is checked at a very early state in the connection
3193 processing. Therefore, <code class="directive">LogLevelOverride</code> allows to
3194 change the log level for things like the SSL handshake which happen before
3195 a <code class="directive"><a href="#loglevel">LogLevel</a></code> directive in an
3196 <code class="directive"><a href="#if"><If></a></code> container would
3199 <p><code class="directive">LogLevelOverride</code> accepts either a single
3200 IP-address or a CIDR IP-address/len subnet specification.
3201 For the syntax of the loglevel specification, see the
3202 <code class="directive"><a href="#loglevel">LogLevel</a></code> directive.</p>
3204 <p>For requests that match a <code class="directive">LogLevelOverride</code>
3205 directive, per-directory specifications of
3206 <code class="directive"><a href="#loglevel">LogLevel</a></code> are ignored.</p>
3210 <pre class="prettyprint lang-config"> LogLevelOverride 192.0.2.0/24 ssl:trace6
3211 LogLevelOverride 192.0.2.7 ssl:trace8</pre>
3215 <code class="directive">LogLevelOverride</code> only affects
3216 log messages that are associated with the request or the connection.
3217 Log messages which are associated with the server are not affected.
3223 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
3226 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3227 <div class="directive-section"><h2><a name="MaxKeepAliveRequests" id="MaxKeepAliveRequests">MaxKeepAliveRequests</a> <a name="maxkeepaliverequests" id="maxkeepaliverequests">Directive</a></h2>
3228 <table class="directive">
3229 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of requests allowed on a persistent
3230 connection</td></tr>
3231 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxKeepAliveRequests <var>number</var></code></td></tr>
3232 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxKeepAliveRequests 100</code></td></tr>
3233 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3234 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3235 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3237 <p>The <code class="directive">MaxKeepAliveRequests</code> directive
3238 limits the number of requests allowed per connection when
3239 <code class="directive"><a href="#keepalive">KeepAlive</a></code> is on. If it is
3240 set to <code>0</code>, unlimited requests will be allowed. We
3241 recommend that this setting be kept to a high value for maximum
3242 server performance.</p>
3246 <pre class="prettyprint lang-config">MaxKeepAliveRequests 500</pre>
3250 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3251 <div class="directive-section"><h2><a name="MaxRangeOverlaps" id="MaxRangeOverlaps">MaxRangeOverlaps</a> <a name="maxrangeoverlaps" id="maxrangeoverlaps">Directive</a></h2>
3252 <table class="directive">
3253 <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
3255 <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>
3256 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeOverlaps 20</code></td></tr>
3257 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3258 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3259 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3260 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3262 <p>The <code class="directive">MaxRangeOverlaps</code> directive
3263 limits the number of overlapping HTTP ranges the server is willing to
3264 return to the client. If more overlapping ranges than permitted are requested,
3265 the complete resource is returned instead.</p>
3268 <dt><strong>default</strong></dt>
3269 <dd>Limits the number of overlapping ranges to a compile-time default of 20.</dd>
3271 <dt><strong>none</strong></dt>
3272 <dd>No overlapping Range headers are allowed.</dd>
3274 <dt><strong>unlimited</strong></dt>
3275 <dd>The server does not limit the number of overlapping ranges it is
3276 willing to satisfy.</dd>
3278 <dt><var>number-of-ranges</var></dt>
3279 <dd>A positive number representing the maximum number of overlapping ranges the
3280 server is willing to satisfy.</dd>
3284 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3285 <div class="directive-section"><h2><a name="MaxRangeReversals" id="MaxRangeReversals">MaxRangeReversals</a> <a name="maxrangereversals" id="maxrangereversals">Directive</a></h2>
3286 <table class="directive">
3287 <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
3289 <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>
3290 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeReversals 20</code></td></tr>
3291 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3292 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3293 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3294 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3296 <p>The <code class="directive">MaxRangeReversals</code> directive
3297 limits the number of HTTP Range reversals the server is willing to
3298 return to the client. If more ranges reversals than permitted are requested,
3299 the complete resource is returned instead.</p>
3302 <dt><strong>default</strong></dt>
3303 <dd>Limits the number of range reversals to a compile-time default of 20.</dd>
3305 <dt><strong>none</strong></dt>
3306 <dd>No Range reversals headers are allowed.</dd>
3308 <dt><strong>unlimited</strong></dt>
3309 <dd>The server does not limit the number of range reversals it is
3310 willing to satisfy.</dd>
3312 <dt><var>number-of-ranges</var></dt>
3313 <dd>A positive number representing the maximum number of range reversals the
3314 server is willing to satisfy.</dd>
3318 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3319 <div class="directive-section"><h2><a name="MaxRanges" id="MaxRanges">MaxRanges</a> <a name="maxranges" id="maxranges">Directive</a></h2>
3320 <table class="directive">
3321 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of ranges allowed before returning the complete
3323 <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>
3324 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRanges 200</code></td></tr>
3325 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3326 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3327 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3328 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3330 <p>The <code class="directive">MaxRanges</code> directive
3331 limits the number of HTTP ranges the server is willing to
3332 return to the client. If more ranges than permitted are requested,
3333 the complete resource is returned instead.</p>
3336 <dt><strong>default</strong></dt>
3337 <dd>Limits the number of ranges to a compile-time default of 200.</dd>
3339 <dt><strong>none</strong></dt>
3340 <dd>Range headers are ignored.</dd>
3342 <dt><strong>unlimited</strong></dt>
3343 <dd>The server does not limit the number of ranges it is
3344 willing to satisfy.</dd>
3346 <dt><var>number-of-ranges</var></dt>
3347 <dd>A positive number representing the maximum number of ranges the
3348 server is willing to satisfy.</dd>
3352 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3353 <div class="directive-section"><h2><a name="MergeTrailers" id="MergeTrailers">MergeTrailers</a> <a name="mergetrailers" id="mergetrailers">Directive</a></h2>
3354 <table class="directive">
3355 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether trailers are merged into headers</td></tr>
3356 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MergeTrailers [on|off]</code></td></tr>
3357 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MergeTrailers off</code></td></tr>
3358 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3359 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3360 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3361 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.4.11 and later</td></tr>
3363 <p>This directive controls whether HTTP trailers are copied into the
3364 internal representation of HTTP headers. This merging occurs when the
3365 request body has been completely consumed, long after most header
3366 processing would have a chance to examine or modify request headers.</p>
3367 <p>This option is provided for compatibility with releases prior to 2.4.11,
3368 where trailers were always merged.</p>
3371 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3372 <div class="directive-section"><h2><a name="Mutex" id="Mutex">Mutex</a> <a name="mutex" id="mutex">Directive</a></h2>
3373 <table class="directive">
3374 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures mutex mechanism and lock file directory for all
3375 or specified mutexes</td></tr>
3376 <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>
3377 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Mutex default</code></td></tr>
3378 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3379 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3380 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3381 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.4 and later</td></tr>
3383 <p>The <code class="directive">Mutex</code> directive sets the mechanism,
3384 and optionally the lock file location, that httpd and modules use
3385 to serialize access to resources. Specify <code>default</code> as
3386 the second argument to change the settings for all mutexes; specify
3387 a mutex name (see table below) as the second argument to override
3388 defaults only for that mutex.</p>
3390 <p>The <code class="directive">Mutex</code> directive is typically used in
3391 the following exceptional situations:</p>
3394 <li>change the mutex mechanism when the default mechanism selected
3395 by <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> has a functional or performance
3398 <li>change the directory used by file-based mutexes when the
3399 default directory does not support locking</li>
3402 <div class="note"><h3>Supported modules</h3>
3403 <p>This directive only configures mutexes which have been registered
3404 with the core server using the <code>ap_mutex_register()</code> API.
3405 All modules bundled with httpd support the <code class="directive">Mutex</code>
3406 directive, but third-party modules may not. Consult the documentation
3407 of the third-party module, which must indicate the mutex name(s) which
3408 can be configured if this directive is supported.</p>
3411 <p>The following mutex <em>mechanisms</em> are available:</p>
3413 <li><code>default | yes</code>
3414 <p>This selects the default locking implementation, as determined by
3415 <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a>. The default locking implementation can
3416 be displayed by running <code class="program"><a href="../programs/httpd.html">httpd</a></code> with the
3417 <code>-V</code> option.</p></li>
3419 <li><code>none | no</code>
3420 <p>This effectively disables the mutex, and is only allowed for a
3421 mutex if the module indicates that it is a valid choice. Consult the
3422 module documentation for more information.</p></li>
3424 <li><code>posixsem</code>
3425 <p>This is a mutex variant based on a Posix semaphore.</p>
3427 <div class="warning"><h3>Warning</h3>
3428 <p>The semaphore ownership is not recovered if a thread in the process
3429 holding the mutex segfaults, resulting in a hang of the web server.</p>
3433 <li><code>sysvsem</code>
3434 <p>This is a mutex variant based on a SystemV IPC semaphore.</p>
3436 <div class="warning"><h3>Warning</h3>
3437 <p>It is possible to "leak" SysV semaphores if processes crash
3438 before the semaphore is removed.</p>
3441 <div class="warning"><h3>Security</h3>
3442 <p>The semaphore API allows for a denial of service attack by any
3443 CGIs running under the same uid as the webserver (<em>i.e.</em>,
3444 all CGIs, unless you use something like <code class="program"><a href="../programs/suexec.html">suexec</a></code>
3445 or <code>cgiwrapper</code>).</p>
3449 <li><code>sem</code>
3450 <p>This selects the "best" available semaphore implementation, choosing
3451 between Posix and SystemV IPC semaphores, in that order.</p></li>
3453 <li><code>pthread</code>
3454 <p>This is a mutex variant based on cross-process Posix thread
3457 <div class="warning"><h3>Warning</h3>
3458 <p>On most systems, if a child process terminates abnormally while
3459 holding a mutex that uses this implementation, the server will deadlock
3460 and stop responding to requests. When this occurs, the server will
3461 require a manual restart to recover.</p>
3462 <p>Solaris and Linux are notable exceptions as they provide a mechanism which
3463 usually allows the mutex to be recovered after a child process
3464 terminates abnormally while holding a mutex.</p>
3465 <p>If your system is POSIX compliant or if it implements the
3466 <code>pthread_mutexattr_setrobust_np()</code> function, you may be able
3467 to use the <code>pthread</code> option safely.</p>
3471 <li><code>fcntl:/path/to/mutex</code>
3472 <p>This is a mutex variant where a physical (lock-)file and the
3473 <code>fcntl()</code> function are used as the mutex.</p>
3475 <div class="warning"><h3>Warning</h3>
3476 <p>When multiple mutexes based on this mechanism are used within
3477 multi-threaded, multi-process environments, deadlock errors (EDEADLK)
3478 can be reported for valid mutex operations if <code>fcntl()</code>
3479 is not thread-aware, such as on Solaris.</p>
3483 <li><code>flock:/path/to/mutex</code>
3484 <p>This is similar to the <code>fcntl:/path/to/mutex</code> method
3485 with the exception that the <code>flock()</code> function is used to
3486 provide file locking.</p></li>
3488 <li><code>file:/path/to/mutex</code>
3489 <p>This selects the "best" available file locking implementation,
3490 choosing between <code>fcntl</code> and <code>flock</code>, in that
3494 <p>Most mechanisms are only available on selected platforms, where the
3495 underlying platform and <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> support it. Mechanisms
3496 which aren't available on all platforms are <em>posixsem</em>,
3497 <em>sysvsem</em>, <em>sem</em>, <em>pthread</em>, <em>fcntl</em>,
3498 <em>flock</em>, and <em>file</em>.</p>
3500 <p>With the file-based mechanisms <em>fcntl</em> and <em>flock</em>,
3501 the path, if provided, is a directory where the lock file will be created.
3502 The default directory is httpd's run-time file directory,
3503 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. If a relative
3504 path is provided, it is relative to
3505 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. Always use a local
3506 disk filesystem for <code>/path/to/mutex</code> and never a directory residing
3507 on a NFS- or AFS-filesystem. The basename of the file will be the mutex
3508 type, an optional instance string provided by the module, and unless the
3509 <code>OmitPID</code> keyword is specified, the process id of the httpd
3510 parent process will be appended to make the file name unique, avoiding
3511 conflicts when multiple httpd instances share a lock file directory. For
3512 example, if the mutex name is <code>mpm-accept</code> and the lock file
3513 directory is <code>/var/httpd/locks</code>, the lock file name for the
3514 httpd instance with parent process id 12345 would be
3515 <code>/var/httpd/locks/mpm-accept.12345</code>.</p>
3517 <div class="warning"><h3>Security</h3>
3518 <p>It is best to <em>avoid</em> putting mutex files in a world-writable
3519 directory such as <code>/var/tmp</code> because someone could create
3520 a denial of service attack and prevent the server from starting by
3521 creating a lockfile with the same name as the one the server will try
3525 <p>The following table documents the names of mutexes used by httpd
3526 and bundled modules.</p>
3528 <table class="bordered"><tr class="header">
3531 <th>Protected resource</th>
3534 <td><code>mpm-accept</code></td>
3535 <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>
3536 <td>incoming connections, to avoid the thundering herd problem;
3537 for more information, refer to the
3538 <a href="../misc/perf-tuning.html">performance tuning</a>
3542 <td><code>authdigest-client</code></td>
3543 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3544 <td>client list in shared memory</td>
3547 <td><code>authdigest-opaque</code></td>
3548 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3549 <td>counter in shared memory</td>
3552 <td><code>ldap-cache</code></td>
3553 <td><code class="module"><a href="../mod/mod_ldap.html">mod_ldap</a></code></td>
3554 <td>LDAP result cache</td>
3557 <td><code>rewrite-map</code></td>
3558 <td><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></td>
3559 <td>communication with external mapping programs, to avoid
3560 intermixed I/O from multiple requests</td>
3563 <td><code>ssl-cache</code></td>
3564 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3565 <td>SSL session cache</td>
3568 <td><code>ssl-stapling</code></td>
3569 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3570 <td>OCSP stapling response cache</td>
3573 <td><code>watchdog-callback</code></td>
3574 <td><code class="module"><a href="../mod/mod_watchdog.html">mod_watchdog</a></code></td>
3575 <td>callback function of a particular client module</td>
3579 <p>The <code>OmitPID</code> keyword suppresses the addition of the httpd
3580 parent process id from the lock file name.</p>
3582 <p>In the following example, the mutex mechanism for the MPM accept
3583 mutex will be changed from the compiled-in default to <code>fcntl</code>,
3584 with the associated lock file created in directory
3585 <code>/var/httpd/locks</code>. The mutex mechanism for all other mutexes
3586 will be changed from the compiled-in default to <code>sysvsem</code>.</p>
3588 <pre class="prettyprint lang-config">Mutex sysvsem default
3589 Mutex fcntl:/var/httpd/locks mpm-accept</pre>
3593 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3594 <div class="directive-section"><h2><a name="NameVirtualHost" id="NameVirtualHost">NameVirtualHost</a> <a name="namevirtualhost" id="namevirtualhost">Directive</a></h2>
3595 <table class="directive">
3596 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>DEPRECATED: Designates an IP address for name-virtual
3598 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NameVirtualHost <var>addr</var>[:<var>port</var>]</code></td></tr>
3599 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3600 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3601 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3604 <p>Prior to 2.3.11, <code class="directive">NameVirtualHost</code> was required
3605 to instruct the server that a particular IP address and port combination
3606 was usable as a name-based virtual host. In 2.3.11 and later,
3607 any time an IP address and port combination is used in multiple virtual
3608 hosts, name-based virtual hosting is automatically enabled for that address.</p>
3610 <p>This directive currently has no effect.</p>
3614 <li><a href="../vhosts/">Virtual Hosts
3615 documentation</a></li>
3618 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3619 <div class="directive-section"><h2><a name="Options" id="Options">Options</a> <a name="options" id="options">Directive</a></h2>
3620 <table class="directive">
3621 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures what features are available in a particular
3623 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Options
3624 [+|-]<var>option</var> [[+|-]<var>option</var>] ...</code></td></tr>
3625 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Options FollowSymlinks</code></td></tr>
3626 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3627 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
3628 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3629 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3630 <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>
3632 <p>The <code class="directive">Options</code> directive controls which
3633 server features are available in a particular directory.</p>
3635 <p><var>option</var> can be set to <code>None</code>, in which
3636 case none of the extra features are enabled, or one or more of
3640 <dt><code>All</code></dt>
3642 <dd>All options except for <code>MultiViews</code>.</dd>
3644 <dt><code>ExecCGI</code></dt>
3647 Execution of CGI scripts using <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>
3650 <dt><code>FollowSymLinks</code></dt>
3653 The server will follow symbolic links in this directory. This is
3654 the default setting.
3656 <p>Even though the server follows the symlink it does <em>not</em>
3657 change the pathname used to match against <code class="directive"><a href="#directory"><Directory></a></code> sections.</p>
3659 <p>The <code>FollowSymLinks</code> and
3660 <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
3661 <code>.htaccess</code> files.</p>
3663 <p>Omitting this option should not be considered a security restriction,
3664 since symlink testing is subject to race conditions that make it
3668 <dt><code>Includes</code></dt>
3671 Server-side includes provided by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
3674 <dt><code>IncludesNOEXEC</code></dt>
3678 Server-side includes are permitted, but the <code>#exec
3679 cmd</code> and <code>#exec cgi</code> are disabled. It is still
3680 possible to <code>#include virtual</code> CGI scripts from
3681 <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>ed
3684 <dt><code>Indexes</code></dt>
3687 If a URL which maps to a directory is requested and there
3688 is no <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
3689 (<em>e.g.</em>, <code>index.html</code>) in that directory, then
3690 <code class="module"><a href="../mod/mod_autoindex.html">mod_autoindex</a></code> will return a formatted listing
3691 of the directory.</dd>
3693 <dt><code>MultiViews</code></dt>
3696 <a href="../content-negotiation.html">Content negotiated</a>
3697 "MultiViews" are allowed using
3698 <code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code>.
3699 <div class="note"><h3>Note</h3> <p>This option gets ignored if set
3700 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>
3701 needs real resources to compare against and evaluate from.</p></div>
3704 <dt><code>SymLinksIfOwnerMatch</code></dt>
3706 <dd>The server will only follow symbolic links for which the
3707 target file or directory is owned by the same user id as the
3710 <div class="note"><h3>Note</h3>
3711 <p>The <code>FollowSymLinks</code> and
3712 <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
3713 <code>.htaccess</code> files.</p>
3715 <p>This option should not be considered a security restriction,
3716 since symlink testing is subject to race conditions that make it
3721 <p>Normally, if multiple <code class="directive">Options</code> could
3722 apply to a directory, then the most specific one is used and
3723 others are ignored; the options are not merged. (See <a href="../sections.html#merging">how sections are merged</a>.)
3724 However if <em>all</em> the options on the
3725 <code class="directive">Options</code> directive are preceded by a
3726 <code>+</code> or <code>-</code> symbol, the options are
3727 merged. Any options preceded by a <code>+</code> are added to the
3728 options currently in force, and any options preceded by a
3729 <code>-</code> are removed from the options currently in
3732 <div class="note"><h3>Note</h3>
3733 <p>Mixing <code class="directive">Options</code> with a <code>+</code> or
3734 <code>-</code> with those without is not valid syntax and will be
3735 rejected during server startup by the syntax check with an abort.</p>
3738 <p>For example, without any <code>+</code> and <code>-</code> symbols:</p>
3740 <pre class="prettyprint lang-config"><Directory "/web/docs">
3741 Options Indexes FollowSymLinks
3744 <Directory "/web/docs/spec">
3746 </Directory></pre>
3749 <p>then only <code>Includes</code> will be set for the
3750 <code>/web/docs/spec</code> directory. However if the second
3751 <code class="directive">Options</code> directive uses the <code>+</code> and
3752 <code>-</code> symbols:</p>
3754 <pre class="prettyprint lang-config"><Directory "/web/docs">
3755 Options Indexes FollowSymLinks
3758 <Directory "/web/docs/spec">
3759 Options +Includes -Indexes
3760 </Directory></pre>
3763 <p>then the options <code>FollowSymLinks</code> and
3764 <code>Includes</code> are set for the <code>/web/docs/spec</code>
3767 <div class="note"><h3>Note</h3>
3768 <p>Using <code>-IncludesNOEXEC</code> or
3769 <code>-Includes</code> disables server-side includes completely
3770 regardless of the previous setting.</p>
3773 <p>The default in the absence of any other settings is
3774 <code>FollowSymlinks</code>.</p>
3777 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3778 <div class="directive-section"><h2><a name="Protocol" id="Protocol">Protocol</a> <a name="protocol" id="protocol">Directive</a></h2>
3779 <table class="directive">
3780 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocol for a listening socket</td></tr>
3781 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocol <var>protocol</var></code></td></tr>
3782 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3783 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3784 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3785 <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>
3787 <p>This directive specifies the protocol used for a specific listening socket.
3788 The protocol is used to determine which module should handle a request and
3789 to apply protocol specific optimizations with the <code class="directive">AcceptFilter</code>
3792 <p>You only need to set the protocol if you are running on non-standard ports;
3793 otherwise, <code>http</code> is assumed for port 80 and <code>https</code>
3796 <p>For example, if you are running <code>https</code> on a non-standard port,
3797 specify the protocol explicitly:</p>
3799 <pre class="prettyprint lang-config">Protocol https</pre>
3802 <p>You can also specify the protocol using the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code> directive.</p>
3806 <li><code class="directive"><a href="#acceptfilter">AcceptFilter</a></code></li>
3807 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
3810 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3811 <div class="directive-section"><h2><a name="Protocols" id="Protocols">Protocols</a> <a name="protocols" id="protocols">Directive</a></h2>
3812 <table class="directive">
3813 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocols available for a server/virtual host</td></tr>
3814 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocols <var>protocol</var> ...</code></td></tr>
3815 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Protocols http/1.1</code></td></tr>
3816 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3817 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3818 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3819 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3821 <p>This directive specifies the list of protocols supported for a
3822 server/virtual host. The list determines the allowed protocols
3823 a client may negotiate for this server/host.</p>
3825 <p>You need to set protocols if you want to extend the available
3826 protocols for a server/host. By default, only the http/1.1 protocol
3827 (which includes the compatibility with 1.0 and 0.9 clients) is
3830 <p>For example, if you want to support HTTP/2 for a server with TLS,
3833 <pre class="prettyprint lang-config">Protocols h2 http/1.1</pre>
3836 <p>Valid protocols are <code>http/1.1</code> for http and https connections,
3837 <code>h2</code> on https connections and <code>h2c</code> for http
3838 connections. Modules may enable more protocols.</p>
3840 <p>It is safe to specify protocols that are unavailable/disabled. Such
3841 protocol names will simply be ignored.</p>
3843 <p>Protocols specified in base servers are inherited for virtual hosts
3844 only if the virtual host has no own Protocols directive. Or, the other
3845 way around, Protocols directives in virtual hosts replace any
3846 such directive in the base server.
3852 <li><code class="directive"><a href="#protocolshonororder">ProtocolsHonorOrder</a></code></li>
3855 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3856 <div class="directive-section"><h2><a name="ProtocolsHonorOrder" id="ProtocolsHonorOrder">ProtocolsHonorOrder</a> <a name="protocolshonororder" id="protocolshonororder">Directive</a></h2>
3857 <table class="directive">
3858 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines if order of Protocols determines precedence during negotiation</td></tr>
3859 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProtocolsHonorOrder On|Off</code></td></tr>
3860 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProtocolsHonorOrder On</code></td></tr>
3861 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3862 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3863 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3864 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3866 <p>This directive specifies if the server should honor the order in which
3867 the <code class="directive">Protocols</code> directive lists protocols.</p>
3869 <p>If configured Off, the client supplied list order of protocols has
3870 precedence over the order in the server configuration.</p>
3872 <p>With <code class="directive">ProtocolsHonorOrder</code> set to <code>on</code>
3873 (default), the client ordering does not matter and only the ordering
3874 in the server settings influences the outcome of the protocol
3880 <li><code class="directive"><a href="#protocols">Protocols</a></code></li>
3883 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3884 <div class="directive-section"><h2><a name="QualifyRedirectURL" id="QualifyRedirectURL">QualifyRedirectURL</a> <a name="qualifyredirecturl" id="qualifyredirecturl">Directive</a></h2>
3885 <table class="directive">
3886 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls whether the REDIRECT_URL environment variable is
3887 fully qualified</td></tr>
3888 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>QualifyRedirectURL ON|OFF</code></td></tr>
3889 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>QualifyRedirectURL OFF</code></td></tr>
3890 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3891 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3892 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3893 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3894 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directive supported in 2.4.18 and later. 2.4.17 acted
3895 as if 'QualifyRedirectURL ON' was configured.</td></tr>
3897 <p>This directive controls whether the server will ensure that the
3898 REDIRECT_URL environment variable is fully qualified. By default,
3899 the variable contains the verbatim URL requested by the client,
3900 such as "/index.html". With <code class="directive"><a href="#qualifyredirecturl on">QualifyRedirectURL ON</a></code>, the same request would result in a
3901 value such as "http://www.example.com/index.html".</p>
3902 <p>Even without this directive set, when a request is issued against a
3903 fully qualified URL, REDIRECT_URL will remain fully qualified.
3907 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3908 <div class="directive-section"><h2><a name="RegisterHttpMethod" id="RegisterHttpMethod">RegisterHttpMethod</a> <a name="registerhttpmethod" id="registerhttpmethod">Directive</a></h2>
3909 <table class="directive">
3910 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Register non-standard HTTP methods</td></tr>
3911 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RegisterHttpMethod <var>method</var> [<var>method</var> [...]]</code></td></tr>
3912 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3913 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3914 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3916 <p>HTTP Methods that are not conforming to the relvant RFCs are normally
3917 rejected by request processing in Apache HTTPD. To avoid this, modules
3918 can register non-standard HTTP methods they support.
3919 The <code class="directive">RegisterHttpMethod</code> allows to register such
3920 methods manually. This can be useful if such methods are forwarded
3921 for external processing, e.g. to a CGI script.</p>
3924 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3925 <div class="directive-section"><h2><a name="RLimitCPU" id="RLimitCPU">RLimitCPU</a> <a name="rlimitcpu" id="rlimitcpu">Directive</a></h2>
3926 <table class="directive">
3927 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the CPU consumption of processes launched
3928 by Apache httpd children</td></tr>
3929 <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>
3930 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3931 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3932 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3933 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3934 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3936 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3937 resource limit for all processes and the second parameter sets
3938 the maximum resource limit. Either parameter can be a number,
3939 or <code>max</code> to indicate to the server that the limit should
3940 be set to the maximum allowed by the operating system
3941 configuration. Raising the maximum resource limit requires that
3942 the server is running as <code>root</code> or in the initial startup
3945 <p>This applies to processes forked from Apache httpd children
3946 servicing requests, not the Apache httpd children themselves. This
3947 includes CGI scripts and SSI exec commands, but not any
3948 processes forked from the Apache httpd parent, such as piped
3951 <p>CPU resource limits are expressed in seconds per
3956 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
3957 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3960 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3961 <div class="directive-section"><h2><a name="RLimitMEM" id="RLimitMEM">RLimitMEM</a> <a name="rlimitmem" id="rlimitmem">Directive</a></h2>
3962 <table class="directive">
3963 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the memory consumption of processes launched
3964 by Apache httpd children</td></tr>
3965 <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>
3966 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3967 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3968 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3969 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3970 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3972 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3973 resource limit for all processes and the second parameter sets
3974 the maximum resource limit. Either parameter can be a number,
3975 or <code>max</code> to indicate to the server that the limit should
3976 be set to the maximum allowed by the operating system
3977 configuration. Raising the maximum resource limit requires that
3978 the server is running as <code>root</code> or in the initial startup
3981 <p>This applies to processes forked from Apache httpd children
3982 servicing requests, not the Apache httpd children themselves. This
3983 includes CGI scripts and SSI exec commands, but not any
3984 processes forked from the Apache httpd parent, such as piped
3987 <p>Memory resource limits are expressed in bytes per
3992 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
3993 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3996 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3997 <div class="directive-section"><h2><a name="RLimitNPROC" id="RLimitNPROC">RLimitNPROC</a> <a name="rlimitnproc" id="rlimitnproc">Directive</a></h2>
3998 <table class="directive">
3999 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of processes that can be launched by
4000 processes launched by Apache httpd children</td></tr>
4001 <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>
4002 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
4003 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4004 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
4005 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4006 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4008 <p>Takes 1 or 2 parameters. The first parameter sets the soft
4009 resource limit for all processes, and the second parameter sets
4010 the maximum resource limit. Either parameter can be a number,
4011 or <code>max</code> to indicate to the server that the limit
4012 should be set to the maximum allowed by the operating system
4013 configuration. Raising the maximum resource limit requires that
4014 the server is running as <code>root</code> or in the initial startup
4017 <p>This applies to processes forked from Apache httpd children
4018 servicing requests, not the Apache httpd children themselves. This
4019 includes CGI scripts and SSI exec commands, but not any
4020 processes forked from the Apache httpd parent, such as piped
4023 <p>Process limits control the number of processes per user.</p>
4025 <div class="note"><h3>Note</h3>
4026 <p>If CGI processes are <strong>not</strong> running
4027 under user ids other than the web server user id, this directive
4028 will limit the number of processes that the server itself can
4029 create. Evidence of this situation will be indicated by
4030 <strong><code>cannot fork</code></strong> messages in the
4031 <code>error_log</code>.</p>
4036 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
4037 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
4040 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4041 <div class="directive-section"><h2><a name="ScriptInterpreterSource" id="ScriptInterpreterSource">ScriptInterpreterSource</a> <a name="scriptinterpretersource" id="scriptinterpretersource">Directive</a></h2>
4042 <table class="directive">
4043 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
4045 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ScriptInterpreterSource Registry|Registry-Strict|Script</code></td></tr>
4046 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ScriptInterpreterSource Script</code></td></tr>
4047 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4048 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4049 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4050 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4051 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Win32 only.</td></tr>
4053 <p>This directive is used to control how Apache httpd finds the
4054 interpreter used to run CGI scripts. The default setting is
4055 <code>Script</code>. This causes Apache httpd to use the interpreter pointed to
4056 by the shebang line (first line, starting with <code>#!</code>) in the
4057 script. On Win32 systems this line usually looks like:</p>
4059 <pre class="prettyprint lang-perl">#!C:/Perl/bin/perl.exe</pre>
4062 <p>or, if <code>perl</code> is in the <code>PATH</code>, simply:</p>
4064 <pre class="prettyprint lang-perl">#!perl</pre>
4067 <p>Setting <code>ScriptInterpreterSource Registry</code> will
4068 cause the Windows Registry tree <code>HKEY_CLASSES_ROOT</code> to be
4069 searched using the script file extension (e.g., <code>.pl</code>) as a
4070 search key. The command defined by the registry subkey
4071 <code>Shell\ExecCGI\Command</code> or, if it does not exist, by the subkey
4072 <code>Shell\Open\Command</code> is used to open the script file. If the
4073 registry keys cannot be found, Apache httpd falls back to the behavior of the
4074 <code>Script</code> option.</p>
4076 <div class="warning"><h3>Security</h3>
4077 <p>Be careful when using <code>ScriptInterpreterSource
4078 Registry</code> with <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories, because
4079 Apache httpd will try to execute <strong>every</strong> file within this
4080 directory. The <code>Registry</code> setting may cause undesired
4081 program calls on files which are typically not executed. For
4082 example, the default open command on <code>.htm</code> files on
4083 most Windows systems will execute Microsoft Internet Explorer, so
4084 any HTTP request for an <code>.htm</code> file existing within the
4085 script directory would start the browser in the background on the
4086 server. This is a good way to crash your system within a minute or
4090 <p>The option <code>Registry-Strict</code> which is new in Apache HTTP Server
4091 2.0 does the same thing as <code>Registry</code> but uses only the
4092 subkey <code>Shell\ExecCGI\Command</code>. The
4093 <code>ExecCGI</code> key is not a common one. It must be
4094 configured manually in the windows registry and hence prevents
4095 accidental program calls on your system.</p>
4098 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4099 <div class="directive-section"><h2><a name="SeeRequestTail" id="SeeRequestTail">SeeRequestTail</a> <a name="seerequesttail" id="seerequesttail">Directive</a></h2>
4100 <table class="directive">
4101 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine if mod_status displays the first 63 characters
4102 of a request or the last 63, assuming the request itself is greater than
4104 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SeeRequestTail On|Off</code></td></tr>
4105 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SeeRequestTail Off</code></td></tr>
4106 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4107 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4108 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4110 <p>mod_status with <code>ExtendedStatus On</code>
4111 displays the actual request being handled.
4112 For historical purposes, only 63 characters of the request
4113 are actually stored for display purposes. This directive
4114 controls whether the 1st 63 characters are stored (the previous
4115 behavior and the default) or if the last 63 characters are. This
4116 is only applicable, of course, if the length of the request is
4117 64 characters or greater.</p>
4119 <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:
4122 <table class="bordered">
4124 <th>Off (default)</th>
4125 <td>GET /disk1/storage/apache/htdocs/images/imagestore1/food/apples</td>
4129 <td>orage/apache/htdocs/images/imagestore1/food/apples.jpg HTTP/1.1</td>
4135 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4136 <div class="directive-section"><h2><a name="ServerAdmin" id="ServerAdmin">ServerAdmin</a> <a name="serveradmin" id="serveradmin">Directive</a></h2>
4137 <table class="directive">
4138 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Email address that the server includes in error
4139 messages sent to the client</td></tr>
4140 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAdmin <var>email-address</var>|<var>URL</var></code></td></tr>
4141 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4142 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4143 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4145 <p>The <code class="directive">ServerAdmin</code> sets the contact address
4146 that the server includes in any error messages it returns to the
4147 client. If the <code>httpd</code> doesn't recognize the supplied argument
4149 assumes, that it's an <var>email-address</var> and prepends it with
4150 <code>mailto:</code> in hyperlink targets. However, it's recommended to
4151 actually use an email address, since there are a lot of CGI scripts that
4152 make that assumption. If you want to use an URL, it should point to another
4153 server under your control. Otherwise users may not be able to contact you in
4156 <p>It may be worth setting up a dedicated address for this, e.g.</p>
4158 <pre class="prettyprint lang-config">ServerAdmin www-admin@foo.example.com</pre>
4160 <p>as users do not always mention that they are talking about the
4164 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4165 <div class="directive-section"><h2><a name="ServerAlias" id="ServerAlias">ServerAlias</a> <a name="serveralias" id="serveralias">Directive</a></h2>
4166 <table class="directive">
4167 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Alternate names for a host used when matching requests
4168 to name-virtual hosts</td></tr>
4169 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAlias <var>hostname</var> [<var>hostname</var>] ...</code></td></tr>
4170 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4171 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4172 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4174 <p>The <code class="directive">ServerAlias</code> directive sets the
4175 alternate names for a host, for use with <a href="../vhosts/name-based.html">name-based virtual hosts</a>. The
4176 <code class="directive">ServerAlias</code> may include wildcards, if appropriate.</p>
4178 <pre class="prettyprint lang-config"><VirtualHost *:80>
4179 ServerName server.example.com
4180 ServerAlias server server2.example.com server2
4181 ServerAlias *.example.com
4182 UseCanonicalName Off
4184 </VirtualHost></pre>
4187 <p>Name-based virtual hosts for the best-matching set of <code class="directive"><a href="#virtualhost"><virtualhost></a></code>s are processed
4188 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
4189 (nor for ServerName vs. ServerAlias). </p>
4191 <p>The complete list of names in the <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
4192 directive are treated just like a (non wildcard)
4193 <code class="directive">ServerAlias</code>.</p>
4198 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4199 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4202 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4203 <div class="directive-section"><h2><a name="ServerName" id="ServerName">ServerName</a> <a name="servername" id="servername">Directive</a></h2>
4204 <table class="directive">
4205 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Hostname and port that the server uses to identify
4207 <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>
4208 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4209 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4210 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4212 <p>The <code class="directive">ServerName</code> directive sets the
4213 request scheme, hostname and port that the server uses to identify itself.
4216 <p><code class="directive">ServerName</code> is used (possibly
4217 in conjunction with <code class="directive"><a href="#serveralias">ServerAlias</a></code>) to uniquely
4218 identify a virtual host, when using <a href="../vhosts/name-based.html">name-based virtual hosts</a>.</p>
4220 <p>Additionally, this is used when
4221 creating self-referential redirection URLs when
4222 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> is set to a non-default
4225 <p>For example, if the name of the
4226 machine hosting the web server is <code>simple.example.com</code>,
4227 but the machine also has the DNS alias <code>www.example.com</code>
4228 and you wish the web server to be so identified, the following
4229 directive should be used:</p>
4231 <pre class="prettyprint lang-config">ServerName www.example.com</pre>
4234 <p>The <code class="directive">ServerName</code> directive
4235 may appear anywhere within the definition of a server. However,
4236 each appearance overrides the previous appearance (within that
4239 <p>If no <code class="directive">ServerName</code> is specified, the
4240 server attempts to deduce the client visible hostname by first asking
4241 the operating system for the system hostname, and if that fails,
4242 performing a reverse lookup on an IP address present on the system.</p>
4244 <p>If no port is specified in the
4245 <code class="directive">ServerName</code>, then the server will use the
4246 port from the incoming request. For optimal reliability and
4247 predictability, you should specify an explicit hostname and port
4248 using the <code class="directive">ServerName</code> directive.</p>
4250 <p>If you are using <a href="../vhosts/name-based.html">name-based virtual hosts</a>,
4251 the <code class="directive">ServerName</code> inside a
4252 <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
4253 section specifies what hostname must appear in the request's
4254 <code>Host:</code> header to match this virtual host.</p>
4256 <p>Sometimes, the server runs behind a device that processes SSL,
4257 such as a reverse proxy, load balancer or SSL offload
4258 appliance. When this is the case, specify the
4259 <code>https://</code> scheme and the port number to which the
4260 clients connect in the <code class="directive">ServerName</code> directive
4261 to make sure that the server generates the correct
4262 self-referential URLs.
4265 <p>See the description of the
4266 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> and
4267 <code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code> directives for
4268 settings which determine whether self-referential URLs (e.g., by the
4269 <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> module) will refer to the
4270 specified port, or to the port number given in the client's request.
4273 <div class="warning">
4274 <p>Failure to set <code class="directive">ServerName</code> to a name that
4275 your server can resolve to an IP address will result in a startup
4276 warning. <code>httpd</code> will then use whatever hostname it can
4277 determine, using the system's <code>hostname</code> command. This
4278 will almost never be the hostname you actually want.</p>
4279 <div class="example"><p><code>
4280 httpd: Could not reliably determine the server's fully qualified domain name, using rocinante.local for ServerName
4287 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4288 Apache HTTP Server</a></li>
4289 <li><a href="../vhosts/">Apache HTTP Server virtual host
4290 documentation</a></li>
4291 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4292 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4293 <li><code class="directive"><a href="#serveralias">ServerAlias</a></code></li>
4296 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4297 <div class="directive-section"><h2><a name="ServerPath" id="ServerPath">ServerPath</a> <a name="serverpath" id="serverpath">Directive</a></h2>
4298 <table class="directive">
4299 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Legacy URL pathname for a name-based virtual host that
4300 is accessed by an incompatible browser</td></tr>
4301 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerPath <var>URL-path</var></code></td></tr>
4302 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4303 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4304 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4306 <p>The <code class="directive">ServerPath</code> directive sets the legacy
4307 URL pathname for a host, for use with <a href="../vhosts/">name-based virtual hosts</a>.</p>
4311 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4314 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4315 <div class="directive-section"><h2><a name="ServerRoot" id="ServerRoot">ServerRoot</a> <a name="serverroot" id="serverroot">Directive</a></h2>
4316 <table class="directive">
4317 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server installation</td></tr>
4318 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerRoot <var>directory-path</var></code></td></tr>
4319 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerRoot /usr/local/apache</code></td></tr>
4320 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4321 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4322 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4324 <p>The <code class="directive">ServerRoot</code> directive sets the
4325 directory in which the server lives. Typically it will contain the
4326 subdirectories <code>conf/</code> and <code>logs/</code>. Relative
4327 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
4328 relative to this directory.</p>
4330 <pre class="prettyprint lang-config">ServerRoot "/home/httpd"</pre>
4333 <p>The default location of <code class="directive">ServerRoot</code> may be
4334 modified by using the <code>--prefix</code> argument to
4335 <a href="../programs/configure.html"><code>configure</code></a>, and
4336 most third-party distributions of the server have a different
4337 default location from the one listed above.</p>
4342 <li><a href="../invoking.html">the <code>-d</code>
4343 option to <code>httpd</code></a></li>
4344 <li><a href="../misc/security_tips.html#serverroot">the
4345 security tips</a> for information on how to properly set
4346 permissions on the <code class="directive">ServerRoot</code></li>
4349 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4350 <div class="directive-section"><h2><a name="ServerSignature" id="ServerSignature">ServerSignature</a> <a name="serversignature" id="serversignature">Directive</a></h2>
4351 <table class="directive">
4352 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the footer on server-generated documents</td></tr>
4353 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerSignature On|Off|EMail</code></td></tr>
4354 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerSignature Off</code></td></tr>
4355 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4356 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
4357 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4358 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4360 <p>The <code class="directive">ServerSignature</code> directive allows the
4361 configuration of a trailing footer line under server-generated
4362 documents (error messages, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> ftp directory
4363 listings, <code class="module"><a href="../mod/mod_info.html">mod_info</a></code> output, ...). The reason why you
4364 would want to enable such a footer line is that in a chain of proxies,
4365 the user often has no possibility to tell which of the chained servers
4366 actually produced a returned error message.</p>
4368 <p>The <code>Off</code>
4369 setting, which is the default, suppresses the footer line (and is
4370 therefore compatible with the behavior of Apache-1.2 and
4371 below). The <code>On</code> setting simply adds a line with the
4372 server version number and <code class="directive"><a href="#servername">ServerName</a></code> of the serving virtual host,
4373 and the <code>EMail</code> setting additionally creates a
4374 "mailto:" reference to the <code class="directive"><a href="#serveradmin">ServerAdmin</a></code> of the referenced
4377 <p>After version 2.0.44, the details of the server version number
4378 presented are controlled by the <code class="directive"><a href="#servertokens">ServerTokens</a></code> directive.</p>
4382 <li><code class="directive"><a href="#servertokens">ServerTokens</a></code></li>
4385 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4386 <div class="directive-section"><h2><a name="ServerTokens" id="ServerTokens">ServerTokens</a> <a name="servertokens" id="servertokens">Directive</a></h2>
4387 <table class="directive">
4388 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the <code>Server</code> HTTP response
4390 <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>
4391 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerTokens Full</code></td></tr>
4392 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4393 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4394 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4396 <p>This directive controls whether <code>Server</code> response
4397 header field which is sent back to clients includes a
4398 description of the generic OS-type of the server as well as
4399 information about compiled-in modules.</p>
4402 <dt><code>ServerTokens Full</code> (or not specified)</dt>
4404 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4405 (Unix) PHP/4.2.2 MyMod/1.2</code></dd>
4407 <dt><code>ServerTokens Prod[uctOnly]</code></dt>
4409 <dd>Server sends (<em>e.g.</em>): <code>Server:
4412 <dt><code>ServerTokens Major</code></dt>
4414 <dd>Server sends (<em>e.g.</em>): <code>Server:
4415 Apache/2</code></dd>
4417 <dt><code>ServerTokens Minor</code></dt>
4419 <dd>Server sends (<em>e.g.</em>): <code>Server:
4420 Apache/2.4</code></dd>
4422 <dt><code>ServerTokens Min[imal]</code></dt>
4424 <dd>Server sends (<em>e.g.</em>): <code>Server:
4425 Apache/2.4.2</code></dd>
4427 <dt><code>ServerTokens OS</code></dt>
4429 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4434 <p>This setting applies to the entire server, and cannot be
4435 enabled or disabled on a virtualhost-by-virtualhost basis.</p>
4437 <p>After version 2.0.44, this directive also controls the
4438 information presented by the <code class="directive"><a href="#serversignature">ServerSignature</a></code> directive.</p>
4440 <div class="note">Setting <code class="directive">ServerTokens</code> to less than
4441 <code>minimal</code> is not recommended because it makes it more
4442 difficult to debug interoperational problems. Also note that
4443 disabling the Server: header does nothing at all to make your
4444 server more secure. The idea of "security through obscurity"
4445 is a myth and leads to a false sense of safety.</div>
4449 <li><code class="directive"><a href="#serversignature">ServerSignature</a></code></li>
4452 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4453 <div class="directive-section"><h2><a name="SetHandler" id="SetHandler">SetHandler</a> <a name="sethandler" id="sethandler">Directive</a></h2>
4454 <table class="directive">
4455 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be processed by a
4457 <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>
4458 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4459 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4460 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4461 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4462 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4464 <p>When placed into an <code>.htaccess</code> file or a
4465 <code class="directive"><a href="#directory"><Directory></a></code> or
4466 <code class="directive"><a href="#location"><Location></a></code>
4467 section, this directive forces all matching files to be parsed
4468 through the <a href="../handler.html">handler</a> given by
4469 <var>handler-name</var>. For example, if you had a directory you
4470 wanted to be parsed entirely as imagemap rule files, regardless
4471 of extension, you might put the following into an
4472 <code>.htaccess</code> file in that directory:</p>
4474 <pre class="prettyprint lang-config">SetHandler imap-file</pre>
4477 <p>Another example: if you wanted to have the server display a
4478 status report whenever a URL of
4479 <code>http://servername/status</code> was called, you might put
4480 the following into <code>httpd.conf</code>:</p>
4482 <pre class="prettyprint lang-config"><Location "/status">
4483 SetHandler server-status
4484 </Location></pre>
4487 <p>You could also use this directive to configure a particular
4488 handler for files with a particular file extension. For example:</p>
4490 <pre class="prettyprint lang-config"><FilesMatch "\.php$">
4491 SetHandler application/x-httpd-php
4492 </FilesMatch></pre>
4495 <p>String-valued expressions can be used to reference per-request
4496 variables, including backreferences to named regular expressions:</p>
4498 <pre class="prettyprint lang-config"><LocationMatch ^/app/(?<sub>[^/]+)/>
4499 SetHandler "proxy:unix:/var/run/app_%{env:MATCH_sub}.sock|fcgi://localhost:8080"
4500 </LocationMatch></pre>
4503 <p>You can override an earlier defined <code class="directive">SetHandler</code>
4504 directive by using the value <code>None</code>.</p>
4506 <div class="note"><h3>Note</h3>
4507 <p>Because <code class="directive">SetHandler</code> overrides default handlers,
4508 normal behavior such as handling of URLs ending in a slash (/) as
4509 directories or index files is suppressed.</p></div>
4513 <li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li>
4516 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4517 <div class="directive-section"><h2><a name="SetInputFilter" id="SetInputFilter">SetInputFilter</a> <a name="setinputfilter" id="setinputfilter">Directive</a></h2>
4518 <table class="directive">
4519 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process client requests and POST
4521 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetInputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4522 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4523 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4524 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4525 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4527 <p>The <code class="directive">SetInputFilter</code> directive sets the
4528 filter or filters which will process client requests and POST
4529 input when they are received by the server. This is in addition to
4530 any filters defined elsewhere, including the
4531 <code class="directive"><a href="../mod/mod_mime.html#addinputfilter">AddInputFilter</a></code>
4534 <p>If more than one filter is specified, they must be separated
4535 by semicolons in the order in which they should process the
4540 <li><a href="../filter.html">Filters</a> documentation</li>
4543 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4544 <div class="directive-section"><h2><a name="SetOutputFilter" id="SetOutputFilter">SetOutputFilter</a> <a name="setoutputfilter" id="setoutputfilter">Directive</a></h2>
4545 <table class="directive">
4546 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process responses from the
4548 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetOutputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4549 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4550 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4551 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4552 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4554 <p>The <code class="directive">SetOutputFilter</code> directive sets the filters
4555 which will process responses from the server before they are
4556 sent to the client. This is in addition to any filters defined
4557 elsewhere, including the
4558 <code class="directive"><a href="../mod/mod_mime.html#addoutputfilter">AddOutputFilter</a></code>
4561 <p>For example, the following configuration will process all files
4562 in the <code>/www/data/</code> directory for server-side
4565 <pre class="prettyprint lang-config"><Directory "/www/data/">
4566 SetOutputFilter INCLUDES
4567 </Directory></pre>
4570 <p>If more than one filter is specified, they must be separated
4571 by semicolons in the order in which they should process the
4576 <li><a href="../filter.html">Filters</a> documentation</li>
4579 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4580 <div class="directive-section"><h2><a name="TimeOut" id="TimeOut">TimeOut</a> <a name="timeout" id="timeout">Directive</a></h2>
4581 <table class="directive">
4582 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for
4583 certain events before failing a request</td></tr>
4584 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TimeOut <var>seconds</var></code></td></tr>
4585 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TimeOut 60</code></td></tr>
4586 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4587 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4588 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4590 <p>The <code class="directive">TimeOut</code> directive defines the length
4591 of time Apache httpd will wait for I/O in various circumstances:</p>
4594 <li><p>When reading data from the client, the length of time to
4595 wait for a TCP packet to arrive if the read buffer is
4597 <p> For initial data on a new connection, this directive doesn't
4598 take effect until after any configured <code class="directive"><a href="#acceptfilter">
4599 AcceptFilter</a></code> has passed the new connection to the server.</p>
4602 <li>When writing data to the client, the length of time to wait
4603 for an acknowledgement of a packet if the send buffer is
4606 <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>,
4607 the length of time to wait for output from a CGI script.</li>
4609 <li>In <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>, the length of time to
4610 wait for output from a filtering process.</li>
4612 <li>In <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, the default timeout value if
4613 <code class="directive"><a href="../mod/mod_proxy.html#proxytimeout">ProxyTimeout</a></code> is not
4619 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4620 <div class="directive-section"><h2><a name="TraceEnable" id="TraceEnable">TraceEnable</a> <a name="traceenable" id="traceenable">Directive</a></h2>
4621 <table class="directive">
4622 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines the behavior on <code>TRACE</code> requests</td></tr>
4623 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TraceEnable <var>[on|off|extended]</var></code></td></tr>
4624 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TraceEnable on</code></td></tr>
4625 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4626 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4627 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4629 <p>This directive overrides the behavior of <code>TRACE</code> for both
4630 the core server and <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. The default
4631 <code>TraceEnable on</code> permits <code>TRACE</code> requests per
4632 RFC 2616, which disallows any request body to accompany the request.
4633 <code>TraceEnable off</code> causes the core server and
4634 <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> to return a <code>405</code> (Method not
4635 allowed) error to the client.</p>
4637 <p>Finally, for testing and diagnostic purposes only, request
4638 bodies may be allowed using the non-compliant <code>TraceEnable
4639 extended</code> directive. The core (as an origin server) will
4640 restrict the request body to 64Kb (plus 8Kb for chunk headers if
4641 <code>Transfer-Encoding: chunked</code> is used). The core will
4642 reflect the full headers and all chunk headers with the response
4643 body. As a proxy server, the request body is not restricted to 64Kb.</p>
4645 <div class="note"><h3>Note</h3>
4647 <p>Despite claims to the contrary, enabling the <code>TRACE</code>
4648 method does not expose any security vulnerability in Apache httpd.
4649 The <code>TRACE</code> method is defined by the HTTP/1.1
4650 specification and implementations are expected to support it.</p>
4655 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4656 <div class="directive-section"><h2><a name="UnDefine" id="UnDefine">UnDefine</a> <a name="undefine" id="undefine">Directive</a></h2>
4657 <table class="directive">
4658 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Undefine the existence of a variable</td></tr>
4659 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UnDefine <var>parameter-name</var></code></td></tr>
4660 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4661 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4662 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4664 <p>Undoes the effect of a <code class="directive"><a href="#define">Define</a></code> or
4665 of passing a <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</p>
4666 <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
4667 <code>-D</code> arguments in any startup scripts.</p>
4668 <p>While this directive is supported in virtual host context,
4669 the changes it makes are visible to any later configuration
4670 directives, beyond any enclosing virtual host.</p>
4673 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4674 <div class="directive-section"><h2><a name="UseCanonicalName" id="UseCanonicalName">UseCanonicalName</a> <a name="usecanonicalname" id="usecanonicalname">Directive</a></h2>
4675 <table class="directive">
4676 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own name and
4678 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalName On|Off|DNS</code></td></tr>
4679 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalName Off</code></td></tr>
4680 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4681 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4682 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4684 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4685 URL -- that is, a URL that refers back to the same server. With
4686 <code>UseCanonicalName On</code> Apache httpd will use the hostname and port
4687 specified in the <code class="directive"><a href="#servername">ServerName</a></code>
4688 directive to construct the canonical name for the server. This name
4689 is used in all self-referential URLs, and for the values of
4690 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in CGIs.</p>
4692 <p>With <code>UseCanonicalName Off</code> Apache httpd will form
4693 self-referential URLs using the hostname and port supplied by
4694 the client if any are supplied (otherwise it will use the
4695 canonical name, as defined above). These values are the same
4696 that are used to implement <a href="../vhosts/name-based.html">name-based virtual hosts</a>
4697 and are available with the same clients. The CGI variables
4698 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
4699 constructed from the client supplied values as well.</p>
4701 <p>An example where this may be useful is on an intranet server
4702 where you have users connecting to the machine using short
4703 names such as <code>www</code>. You'll notice that if the users
4704 type a shortname and a URL which is a directory, such as
4705 <code>http://www/splat</code>, <em>without the trailing
4706 slash</em>, then Apache httpd will redirect them to
4707 <code>http://www.example.com/splat/</code>. If you have
4708 authentication enabled, this will cause the user to have to
4709 authenticate twice (once for <code>www</code> and once again
4710 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">
4711 the FAQ on this subject for more information</a>). But if
4712 <code class="directive">UseCanonicalName</code> is set <code>Off</code>, then
4713 Apache httpd will redirect to <code>http://www/splat/</code>.</p>
4715 <p>There is a third option, <code>UseCanonicalName DNS</code>,
4716 which is intended for use with mass IP-based virtual hosting to
4717 support ancient clients that do not provide a
4718 <code>Host:</code> header. With this option, Apache httpd does a
4719 reverse DNS lookup on the server IP address that the client
4720 connected to in order to work out self-referential URLs.</p>
4722 <div class="warning"><h3>Warning</h3>
4723 <p>If CGIs make assumptions about the values of <code>SERVER_NAME</code>,
4724 they may be broken by this option. The client is essentially free
4725 to give whatever value they want as a hostname. But if the CGI is
4726 only using <code>SERVER_NAME</code> to construct self-referential URLs,
4727 then it should be just fine.</p>
4732 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4733 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4734 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4737 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4738 <div class="directive-section"><h2><a name="UseCanonicalPhysicalPort" id="UseCanonicalPhysicalPort">UseCanonicalPhysicalPort</a> <a name="usecanonicalphysicalport" id="usecanonicalphysicalport">Directive</a></h2>
4739 <table class="directive">
4740 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own port</td></tr>
4741 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalPhysicalPort On|Off</code></td></tr>
4742 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalPhysicalPort Off</code></td></tr>
4743 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4744 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4745 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4747 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4748 URL -- that is, a URL that refers back to the same server. With
4749 <code>UseCanonicalPhysicalPort On</code>, Apache httpd will, when
4750 constructing the canonical port for the server to honor
4751 the <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> directive,
4752 provide the actual physical port number being used by this request
4753 as a potential port. With <code>UseCanonicalPhysicalPort Off</code>,
4754 Apache httpd will not ever use the actual physical port number, instead
4755 relying on all configured information to construct a valid port number.</p>
4757 <div class="note"><h3>Note</h3>
4758 <p>The ordering of the lookup when the physical port is used is as
4761 <dt><code>UseCanonicalName On</code></dt>
4764 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4765 <li>Physical port</li>
4766 <li>Default port</li>
4769 <dt><code>UseCanonicalName Off | DNS</code></dt>
4772 <li>Parsed port from <code>Host:</code> header</li>
4773 <li>Physical port</li>
4774 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4775 <li>Default port</li>
4780 <p>With <code>UseCanonicalPhysicalPort Off</code>, the
4781 physical ports are removed from the ordering.</p>
4787 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4788 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4789 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4792 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4793 <div class="directive-section"><h2><a name="VirtualHost" id="VirtualHost"><VirtualHost></a> <a name="virtualhost" id="virtualhost">Directive</a></h2>
4794 <table class="directive">
4795 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only to a specific
4796 hostname or IP address</td></tr>
4797 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><VirtualHost
4798 <var>addr</var>[:<var>port</var>] [<var>addr</var>[:<var>port</var>]]
4799 ...> ... </VirtualHost></code></td></tr>
4800 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4801 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4802 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4804 <p><code class="directive"><VirtualHost></code> and
4805 <code></VirtualHost></code> are used to enclose a group of
4806 directives that will apply only to a particular virtual host. Any
4807 directive that is allowed in a virtual host context may be
4808 used. When the server receives a request for a document on a
4809 particular virtual host, it uses the configuration directives
4810 enclosed in the <code class="directive"><VirtualHost></code>
4811 section. <var>Addr</var> can be any of the following, optionally followed by
4812 a colon and a port number (or *):</p>
4815 <li>The IP address of the virtual host;</li>
4817 <li>A fully qualified domain name for the IP address of the
4818 virtual host (not recommended);</li>
4820 <li>The character <code>*</code>, which acts as a wildcard and matches
4821 any IP address.</li>
4823 <li>The string <code>_default_</code>, which is an alias for <code>*</code></li>
4827 <pre class="prettyprint lang-config"><VirtualHost 10.1.2.3:80>
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>
4837 <p>IPv6 addresses must be specified in square brackets because
4838 the optional port number could not be determined otherwise. An
4839 IPv6 example is shown below:</p>
4841 <pre class="prettyprint lang-config"><VirtualHost [2001:db8::a00:20ff:fea7:ccea]:80>
4842 ServerAdmin webmaster@host.example.com
4843 DocumentRoot "/www/docs/host.example.com"
4844 ServerName host.example.com
4845 ErrorLog "logs/host.example.com-error_log"
4846 TransferLog "logs/host.example.com-access_log"
4847 </VirtualHost></pre>
4850 <p>Each Virtual Host must correspond to a different IP address,
4851 different port number, or a different host name for the server,
4852 in the former case the server machine must be configured to
4853 accept IP packets for multiple addresses. (If the machine does
4854 not have multiple network interfaces, then this can be
4855 accomplished with the <code>ifconfig alias</code> command -- if
4856 your OS supports it).</p>
4858 <div class="note"><h3>Note</h3>
4859 <p>The use of <code class="directive"><VirtualHost></code> does
4860 <strong>not</strong> affect what addresses Apache httpd listens on. You
4861 may need to ensure that Apache httpd is listening on the correct addresses
4862 using <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>.</p>
4865 <p>A <code class="directive"><a href="#servername">ServerName</a></code> should be
4866 specified inside each <code class="directive"><VirtualHost></code> block. If it is absent, the
4867 <code class="directive"><a href="#servername">ServerName</a></code> from the "main"
4868 server configuration will be inherited.</p>
4870 <p>When a request is received, the server first maps it to the best matching
4871 <code class="directive"><VirtualHost></code> based on the local
4872 IP address and port combination only. Non-wildcards have a higher
4873 precedence. If no match based on IP and port occurs at all, the
4874 "main" server configuration is used.</p>
4876 <p>If multiple virtual hosts contain the best matching IP address and port,
4877 the server selects from these virtual hosts the best match based on the
4878 requested hostname. If no matching name-based virtual host is found,
4879 then the first listed virtual host that matched the IP address will be
4880 used. As a consequence, the first listed virtual host for a given IP address
4881 and port combination is the default virtual host for that IP and port
4884 <div class="warning"><h3>Security</h3>
4885 <p>See the <a href="../misc/security_tips.html">security tips</a>
4886 document for details on why your security could be compromised if the
4887 directory where log files are stored is writable by anyone other
4888 than the user that starts the server.</p>
4893 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4894 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4895 Apache HTTP Server</a></li>
4896 <li><a href="../bind.html">Setting
4897 which addresses and ports Apache HTTP Server uses</a></li>
4898 <li><a href="../sections.html">How <Directory>, <Location>
4899 and <Files> sections work</a> for an explanation of how these
4900 different sections are combined when a request is received</li>
4903 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4904 <div class="directive-section"><h2><a name="Warning" id="Warning">Warning</a> <a name="warning" id="warning">Directive</a></h2>
4905 <table class="directive">
4906 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Warn from configuration parsing with a custom message</td></tr>
4907 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Warning <var>message</var></code></td></tr>
4908 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4909 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4910 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4911 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4913 <p>If an issue can be detected from within the configuration, this
4914 directive can be used to generate a custom warning message. The
4915 configuration parsing is not halted. The typical use is to check
4916 whether some user define options are set, and warn if not.</p>
4918 <pre class="prettyprint lang-config"># Example
4919 # tell when ReverseProxy is not set
4920 <IfDefine !ReverseProxy>
4921 Warning "reverse proxy is not started, hope this is okay!"
4924 <IfDefine ReverseProxy>
4925 # define custom proxy configuration
4926 </IfDefine></pre>
4932 <div class="bottomlang">
4933 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
4934 <a href="../en/mod/core.html" title="English"> en </a> |
4935 <a href="../es/mod/core.html" hreflang="es" rel="alternate" title="Español"> es </a> |
4936 <a href="../fr/mod/core.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
4937 <a href="../ja/mod/core.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
4938 <a href="../tr/mod/core.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
4939 </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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