1 <?xml version="1.0" encoding="ISO-8859-1"?>
2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
3 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head>
4 <meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type" />
6 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
7 This file is generated from xml source: DO NOT EDIT
8 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
10 <title>core - Apache HTTP Server Version 2.5</title>
11 <link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
12 <link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
13 <link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" />
14 <script src="../style/scripts/prettify.min.js" type="text/javascript">
17 <link href="../images/favicon.ico" rel="shortcut icon" /></head>
19 <div id="page-header">
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>
22 <img alt="" src="../images/feather.png" /></div>
23 <div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
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> |
31 <a href="../es/mod/core.html" hreflang="es" rel="alternate" title="Español"> es </a> |
32 <a href="../fr/mod/core.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
33 <a href="../ja/mod/core.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
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="#if"><If></a></li>
76 <li><img alt="" src="../images/down.gif" /> <a href="#ifdefine"><IfDefine></a></li>
77 <li><img alt="" src="../images/down.gif" /> <a href="#ifmodule"><IfModule></a></li>
78 <li><img alt="" src="../images/down.gif" /> <a href="#include">Include</a></li>
79 <li><img alt="" src="../images/down.gif" /> <a href="#includeoptional">IncludeOptional</a></li>
80 <li><img alt="" src="../images/down.gif" /> <a href="#keepalive">KeepAlive</a></li>
81 <li><img alt="" src="../images/down.gif" /> <a href="#keepalivetimeout">KeepAliveTimeout</a></li>
82 <li><img alt="" src="../images/down.gif" /> <a href="#limit"><Limit></a></li>
83 <li><img alt="" src="../images/down.gif" /> <a href="#limitexcept"><LimitExcept></a></li>
84 <li><img alt="" src="../images/down.gif" /> <a href="#limitinternalrecursion">LimitInternalRecursion</a></li>
85 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestbody">LimitRequestBody</a></li>
86 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfields">LimitRequestFields</a></li>
87 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfieldsize">LimitRequestFieldSize</a></li>
88 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestline">LimitRequestLine</a></li>
89 <li><img alt="" src="../images/down.gif" /> <a href="#limitxmlrequestbody">LimitXMLRequestBody</a></li>
90 <li><img alt="" src="../images/down.gif" /> <a href="#location"><Location></a></li>
91 <li><img alt="" src="../images/down.gif" /> <a href="#locationmatch"><LocationMatch></a></li>
92 <li><img alt="" src="../images/down.gif" /> <a href="#loglevel">LogLevel</a></li>
93 <li><img alt="" src="../images/down.gif" /> <a href="#logleveloverride">LogLevelOverride</a></li>
94 <li><img alt="" src="../images/down.gif" /> <a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></li>
95 <li><img alt="" src="../images/down.gif" /> <a href="#maxrangeoverlaps">MaxRangeOverlaps</a></li>
96 <li><img alt="" src="../images/down.gif" /> <a href="#maxrangereversals">MaxRangeReversals</a></li>
97 <li><img alt="" src="../images/down.gif" /> <a href="#maxranges">MaxRanges</a></li>
98 <li><img alt="" src="../images/down.gif" /> <a href="#mergetrailers">MergeTrailers</a></li>
99 <li><img alt="" src="../images/down.gif" /> <a href="#mutex">Mutex</a></li>
100 <li><img alt="" src="../images/down.gif" /> <a href="#namevirtualhost">NameVirtualHost</a></li>
101 <li><img alt="" src="../images/down.gif" /> <a href="#options">Options</a></li>
102 <li><img alt="" src="../images/down.gif" /> <a href="#protocol">Protocol</a></li>
103 <li><img alt="" src="../images/down.gif" /> <a href="#protocols">Protocols</a></li>
104 <li><img alt="" src="../images/down.gif" /> <a href="#protocolshonororder">ProtocolsHonorOrder</a></li>
105 <li><img alt="" src="../images/down.gif" /> <a href="#qualifyredirecturl">QualifyRedirectURL</a></li>
106 <li><img alt="" src="../images/down.gif" /> <a href="#registerhttpmethod">RegisterHttpMethod</a></li>
107 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitcpu">RLimitCPU</a></li>
108 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitmem">RLimitMEM</a></li>
109 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitnproc">RLimitNPROC</a></li>
110 <li><img alt="" src="../images/down.gif" /> <a href="#scriptinterpretersource">ScriptInterpreterSource</a></li>
111 <li><img alt="" src="../images/down.gif" /> <a href="#seerequesttail">SeeRequestTail</a></li>
112 <li><img alt="" src="../images/down.gif" /> <a href="#serveradmin">ServerAdmin</a></li>
113 <li><img alt="" src="../images/down.gif" /> <a href="#serveralias">ServerAlias</a></li>
114 <li><img alt="" src="../images/down.gif" /> <a href="#servername">ServerName</a></li>
115 <li><img alt="" src="../images/down.gif" /> <a href="#serverpath">ServerPath</a></li>
116 <li><img alt="" src="../images/down.gif" /> <a href="#serverroot">ServerRoot</a></li>
117 <li><img alt="" src="../images/down.gif" /> <a href="#serversignature">ServerSignature</a></li>
118 <li><img alt="" src="../images/down.gif" /> <a href="#servertokens">ServerTokens</a></li>
119 <li><img alt="" src="../images/down.gif" /> <a href="#sethandler">SetHandler</a></li>
120 <li><img alt="" src="../images/down.gif" /> <a href="#setinputfilter">SetInputFilter</a></li>
121 <li><img alt="" src="../images/down.gif" /> <a href="#setoutputfilter">SetOutputFilter</a></li>
122 <li><img alt="" src="../images/down.gif" /> <a href="#timeout">TimeOut</a></li>
123 <li><img alt="" src="../images/down.gif" /> <a href="#traceenable">TraceEnable</a></li>
124 <li><img alt="" src="../images/down.gif" /> <a href="#undefine">UnDefine</a></li>
125 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalname">UseCanonicalName</a></li>
126 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></li>
127 <li><img alt="" src="../images/down.gif" /> <a href="#virtualhost"><VirtualHost></a></li>
128 <li><img alt="" src="../images/down.gif" /> <a href="#warning">Warning</a></li>
130 <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">Report a bug</a></li></ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
132 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
133 <div class="directive-section"><h2><a name="AcceptFilter" id="AcceptFilter">AcceptFilter</a> <a name="acceptfilter" id="acceptfilter">Directive</a></h2>
134 <table class="directive">
135 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures optimizations for a Protocol's Listener Sockets</td></tr>
136 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptFilter <var>protocol</var> <var>accept_filter</var></code></td></tr>
137 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
138 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
139 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
141 <p>This directive enables operating system specific optimizations for a
142 listening socket by the <code class="directive">Protocol</code> type.
143 The basic premise is for the kernel to not send a socket to the server
144 process until either data is received or an entire HTTP Request is buffered.
145 Only <a href="http://www.freebsd.org/cgi/man.cgi?query=accept_filter&sektion=9">
146 FreeBSD's Accept Filters</a>, Linux's more primitive
147 <code>TCP_DEFER_ACCEPT</code>, and Windows' optimized AcceptEx()
148 are currently supported.</p>
150 <p>Using <code>none</code> for an argument will disable any accept filters
151 for that protocol. This is useful for protocols that require a server
152 send data first, such as <code>ftp:</code> or <code>nntp</code>:</p>
153 <pre class="prettyprint lang-config">AcceptFilter nntp none</pre>
156 <p>The default protocol names are <code>https</code> for port 443
157 and <code>http</code> for all other ports. To specify that another
158 protocol is being used with a listening port, add the <var>protocol</var>
159 argument to the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>
162 <p>The default values on FreeBSD are:</p>
163 <pre class="prettyprint lang-config">AcceptFilter http httpready
164 AcceptFilter https dataready</pre>
167 <p>The <code>httpready</code> accept filter buffers entire HTTP requests at
168 the kernel level. Once an entire request is received, the kernel then
169 sends it to the server. See the
170 <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_http&sektion=9">
171 accf_http(9)</a> man page for more details. Since HTTPS requests are
172 encrypted, only the <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_data&sektion=9">
173 accf_data(9)</a> filter is used.</p>
175 <p>The default values on Linux are:</p>
176 <pre class="prettyprint lang-config">AcceptFilter http data
177 AcceptFilter https data</pre>
180 <p>Linux's <code>TCP_DEFER_ACCEPT</code> does not support buffering http
181 requests. Any value besides <code>none</code> will enable
182 <code>TCP_DEFER_ACCEPT</code> on that listener. For more details
184 <a href="http://homepages.cwi.nl/~aeb/linux/man2html/man7/tcp.7.html">
185 tcp(7)</a> man page.</p>
187 <p>The default values on Windows are:</p>
188 <pre class="prettyprint lang-config">AcceptFilter http data
189 AcceptFilter https data</pre>
192 <p>Window's mpm_winnt interprets the AcceptFilter to toggle the AcceptEx()
193 API, and does not support http protocol buffering. There are two values
194 which utilize the Windows AcceptEx() API and will recycle network
195 sockets between connections. <code>data</code> waits until data has
196 been transmitted as documented above, and the initial data buffer and
197 network endpoint addresses are all retrieved from the single AcceptEx()
198 invocation. <code>connect</code> will use the AcceptEx() API, also
199 retrieve the network endpoint addresses, but like <code>none</code>
200 the <code>connect</code> option does not wait for the initial data
203 <p>On Windows, <code>none</code> uses accept() rather than AcceptEx()
204 and will not recycle sockets between connections. This is useful for
205 network adapters with broken driver support, as well as some virtual
206 network providers such as vpn drivers, or spam, virus or spyware
212 <li><code class="directive"><a href="#protocol">Protocol</a></code></li>
215 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
216 <div class="directive-section"><h2><a name="AcceptPathInfo" id="AcceptPathInfo">AcceptPathInfo</a> <a name="acceptpathinfo" id="acceptpathinfo">Directive</a></h2>
217 <table class="directive">
218 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Resources accept trailing pathname information</td></tr>
219 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptPathInfo On|Off|Default</code></td></tr>
220 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AcceptPathInfo Default</code></td></tr>
221 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
222 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
223 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
224 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
227 <p>This directive controls whether requests that contain trailing
228 pathname information that follows an actual filename (or
229 non-existent file in an existing directory) will be accepted or
230 rejected. The trailing pathname information can be made
231 available to scripts in the <code>PATH_INFO</code> environment
234 <p>For example, assume the location <code>/test/</code> points to
235 a directory that contains only the single file
236 <code>here.html</code>. Then requests for
237 <code>/test/here.html/more</code> and
238 <code>/test/nothere.html/more</code> both collect
239 <code>/more</code> as <code>PATH_INFO</code>.</p>
241 <p>The three possible arguments for the
242 <code class="directive">AcceptPathInfo</code> directive are:</p>
244 <dt><code>Off</code></dt><dd>A request will only be accepted if it
245 maps to a literal path that exists. Therefore a request with
246 trailing pathname information after the true filename such as
247 <code>/test/here.html/more</code> in the above example will return
248 a 404 NOT FOUND error.</dd>
250 <dt><code>On</code></dt><dd>A request will be accepted if a
251 leading path component maps to a file that exists. The above
252 example <code>/test/here.html/more</code> will be accepted if
253 <code>/test/here.html</code> maps to a valid file.</dd>
255 <dt><code>Default</code></dt><dd>The treatment of requests with
256 trailing pathname information is determined by the <a href="../handler.html">handler</a> responsible for the request.
257 The core handler for normal files defaults to rejecting
258 <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
259 <code>PATH_INFO</code> by default.</dd>
262 <p>The primary purpose of the <code>AcceptPathInfo</code>
263 directive is to allow you to override the handler's choice of
264 accepting or rejecting <code>PATH_INFO</code>. This override is required,
265 for example, when you use a <a href="../filter.html">filter</a>, such
266 as <a href="mod_include.html">INCLUDES</a>, to generate content
267 based on <code>PATH_INFO</code>. The core handler would usually reject
268 the request, so you can use the following configuration to enable
271 <pre class="prettyprint lang-config"><Files "mypaths.shtml">
273 SetOutputFilter INCLUDES
280 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
281 <div class="directive-section"><h2><a name="AccessFileName" id="AccessFileName">AccessFileName</a> <a name="accessfilename" id="accessfilename">Directive</a></h2>
282 <table class="directive">
283 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Name of the distributed configuration file</td></tr>
284 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AccessFileName <var>filename</var> [<var>filename</var>] ...</code></td></tr>
285 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AccessFileName .htaccess</code></td></tr>
286 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
287 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
288 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
290 <p>While processing a request, the server looks for
291 the first existing configuration file from this list of names in
292 every directory of the path to the document, if distributed
293 configuration files are <a href="#allowoverride">enabled for that
294 directory</a>. For example:</p>
296 <pre class="prettyprint lang-config">AccessFileName .acl</pre>
299 <p>Before returning the document
300 <code>/usr/local/web/index.html</code>, the server will read
301 <code>/.acl</code>, <code>/usr/.acl</code>,
302 <code>/usr/local/.acl</code> and <code>/usr/local/web/.acl</code>
303 for directives unless they have been disabled with:</p>
305 <pre class="prettyprint lang-config"><Directory "/">
307 </Directory></pre>
312 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
313 <li><a href="../configuring.html">Configuration Files</a></li>
314 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
317 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
318 <div class="directive-section"><h2><a name="AddDefaultCharset" id="AddDefaultCharset">AddDefaultCharset</a> <a name="adddefaultcharset" id="adddefaultcharset">Directive</a></h2>
319 <table class="directive">
320 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Default charset parameter to be added when a response
321 content-type is <code>text/plain</code> or <code>text/html</code></td></tr>
322 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AddDefaultCharset On|Off|<var>charset</var></code></td></tr>
323 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AddDefaultCharset Off</code></td></tr>
324 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
325 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
326 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
327 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
329 <p>This directive specifies a default value for the media type
330 charset parameter (the name of a character encoding) to be added
331 to a response if and only if the response's content-type is either
332 <code>text/plain</code> or <code>text/html</code>. This should override
333 any charset specified in the body of the response via a <code>META</code>
334 element, though the exact behavior is often dependent on the user's client
335 configuration. A setting of <code>AddDefaultCharset Off</code>
336 disables this functionality. <code>AddDefaultCharset On</code> enables
337 a default charset of <code>iso-8859-1</code>. Any other value is assumed
338 to be the <var>charset</var> to be used, which should be one of the
339 <a href="http://www.iana.org/assignments/character-sets">IANA registered
340 charset values</a> for use in Internet media types (MIME types).
343 <pre class="prettyprint lang-config">AddDefaultCharset utf-8</pre>
346 <p><code class="directive">AddDefaultCharset</code> should only be used when all
347 of the text resources to which it applies are known to be in that
348 character encoding and it is too inconvenient to label their charset
349 individually. One such example is to add the charset parameter
350 to resources containing generated content, such as legacy CGI
351 scripts, that might be vulnerable to cross-site scripting attacks
352 due to user-provided data being included in the output. Note, however,
353 that a better solution is to just fix (or delete) those scripts, since
354 setting a default charset does not protect users that have enabled
355 the "auto-detect character encoding" feature on their browser.</p>
359 <li><code class="directive"><a href="../mod/mod_mime.html#addcharset">AddCharset</a></code></li>
362 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
363 <div class="directive-section"><h2><a name="AllowEncodedSlashes" id="AllowEncodedSlashes">AllowEncodedSlashes</a> <a name="allowencodedslashes" id="allowencodedslashes">Directive</a></h2>
364 <table class="directive">
365 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether encoded path separators in URLs are allowed to
366 be passed through</td></tr>
367 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowEncodedSlashes On|Off|NoDecode</code></td></tr>
368 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowEncodedSlashes Off</code></td></tr>
369 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
370 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
371 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
372 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>
373 NoDecode option available in 2.3.12 and later.</td></tr>
375 <p>The <code class="directive">AllowEncodedSlashes</code> directive allows URLs
376 which contain encoded path separators (<code>%2F</code> for <code>/</code>
377 and additionally <code>%5C</code> for <code>\</code> on accordant systems)
378 to be used in the path info.</p>
380 <p>With the default value, <code>Off</code>, such URLs are refused
381 with a 404 (Not found) error.</p>
383 <p>With the value <code>On</code>, such URLs are accepted, and encoded
384 slashes are decoded like all other encoded characters.</p>
386 <p>With the value <code>NoDecode</code>, such URLs are accepted, but
387 encoded slashes are not decoded but left in their encoded state.</p>
389 <p>Turning <code class="directive">AllowEncodedSlashes</code> <code>On</code> is
390 mostly useful when used in conjunction with <code>PATH_INFO</code>.</p>
392 <div class="note"><h3>Note</h3>
393 <p>If encoded slashes are needed in path info, use of <code>NoDecode</code> is
394 strongly recommended as a security measure. Allowing slashes
395 to be decoded could potentially allow unsafe paths.</p>
400 <li><code class="directive"><a href="#acceptpathinfo">AcceptPathInfo</a></code></li>
403 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
404 <div class="directive-section"><h2><a name="AllowOverride" id="AllowOverride">AllowOverride</a> <a name="allowoverride" id="allowoverride">Directive</a></h2>
405 <table class="directive">
406 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Types of directives that are allowed in
407 <code>.htaccess</code> files</td></tr>
408 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverride All|None|<var>directive-type</var>
409 [<var>directive-type</var>] ...</code></td></tr>
410 <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>
411 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
412 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
413 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
415 <p>When the server finds an <code>.htaccess</code> file (as
416 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>),
417 it needs to know which directives declared in that file can override
418 earlier configuration directives.</p>
420 <div class="note"><h3>Only available in <Directory> sections</h3>
421 <code class="directive">AllowOverride</code> is valid only in
422 <code class="directive"><a href="#directory"><Directory></a></code>
423 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
424 <code class="directive"><a href="#files"><Files></a></code> sections.
427 <p>When this directive is set to <code>None</code> and <code class="directive"><a href="#allowoverridelist">AllowOverrideList</a></code> is set to
428 <code>None</code>, <a href="#accessfilename">.htaccess</a> files are
429 completely ignored. In this case, the server will not even attempt
430 to read <code>.htaccess</code> files in the filesystem.</p>
432 <p>When this directive is set to <code>All</code>, then any
433 directive which has the .htaccess <a href="directive-dict.html#Context">Context</a> is allowed in
434 <code>.htaccess</code> files.</p>
436 <p>The <var>directive-type</var> can be one of the following
437 groupings of directives.</p>
444 Allow use of the authorization directives (<code class="directive"><a href="../mod/mod_authz_dbm.html#authdbmgroupfile">AuthDBMGroupFile</a></code>,
445 <code class="directive"><a href="../mod/mod_authn_dbm.html#authdbmuserfile">AuthDBMUserFile</a></code>,
446 <code class="directive"><a href="../mod/mod_authz_groupfile.html#authgroupfile">AuthGroupFile</a></code>,
447 <code class="directive"><a href="../mod/mod_authn_core.html#authname">AuthName</a></code>,
448 <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>
453 Allow use of the directives controlling document types
454 (<code class="directive"><a href="#errordocument">ErrorDocument</a></code>,
455 <code class="directive"><a href="#forcetype">ForceType</a></code>,
456 <code class="directive"><a href="../mod/mod_negotiation.html#languagepriority">LanguagePriority</a></code>,
457 <code class="directive"><a href="#sethandler">SetHandler</a></code>,
458 <code class="directive"><a href="#setinputfilter">SetInputFilter</a></code>,
459 <code class="directive"><a href="#setoutputfilter">SetOutputFilter</a></code>, and
460 <code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code> Add* and Remove* directives),
461 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>),
462 <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>),
463 <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
464 <code class="directive"><a href="../mod/mod_actions.html#action">Action</a></code> from
465 <code class="module"><a href="../mod/mod_actions.html">mod_actions</a></code>.
471 Allow use of the directives controlling directory indexing
472 (<code class="directive"><a href="../mod/mod_autoindex.html#adddescription">AddDescription</a></code>,
473 <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>,
474 <code class="directive"><a href="../mod/mod_autoindex.html#addiconbytype">AddIconByType</a></code>,
475 <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>,
481 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>
486 <dt>Nonfatal=[Override|Unknown|All]</dt>
489 Allow use of AllowOverride option to treat invalid (unrecognized
490 or disallowed) directives in
491 .htaccess as nonfatal. Instead of causing an Internal Server
492 Error, disallowed or unrecognised directives will be ignored
493 and a warning logged:
495 <li><strong>Nonfatal=Override</strong> treats directives
496 forbidden by AllowOverride as nonfatal.</li>
497 <li><strong>Nonfatal=Unknown</strong> treats unknown directives
498 as nonfatal. This covers typos and directives implemented
499 by a module that's not present.</li>
500 <li><strong>Nonfatal=All</strong> treats both the above as nonfatal.</li>
502 <p>Note that a syntax error in a valid directive will still cause
503 an Internal Server Error.</p>
504 <div class="warning"><h3>Security</h3>
505 Nonfatal errors may have security implications for .htaccess users.
506 For example, if AllowOverride disallows AuthConfig, users'
507 configuration designed to restrict access to a site will be disabled.
511 <dt>Options[=<var>Option</var>,...]</dt>
514 Allow use of the directives controlling specific directory
515 features (<code class="directive"><a href="#options">Options</a></code> and
516 <code class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></code>).
517 An equal sign may be given followed by a comma-separated list, without
518 spaces, of options that may be set using the <code class="directive"><a href="#options">Options</a></code> command.
520 <div class="note"><h3>Implicit disabling of Options</h3>
521 <p>Even though the list of options that may be used in .htaccess files
522 can be limited with this directive, as long as any <code class="directive"><a href="#options">Options</a></code> directive is allowed any
523 other inherited option can be disabled by using the non-relative
524 syntax. In other words, this mechanism cannot force a specific option
525 to remain <em>set</em> while allowing any others to be set.
528 <div class="example"><p><code>
529 AllowOverride Options=Indexes,MultiViews
536 <pre class="prettyprint lang-config">AllowOverride AuthConfig Indexes</pre>
539 <p>In the example above, all directives that are neither in the group
540 <code>AuthConfig</code> nor <code>Indexes</code> cause an internal
543 <div class="note"><p>For security and performance reasons, do not set
544 <code>AllowOverride</code> to anything other than <code>None</code>
545 in your <code><Directory "/"></code> block. Instead, find (or
546 create) the <code><Directory></code> block that refers to the
547 directory where you're actually planning to place a
548 <code>.htaccess</code> file.</p>
553 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
554 <li><code class="directive"><a href="#allowoverridelist">AllowOverrideList</a></code></li>
555 <li><a href="../configuring.html">Configuration Files</a></li>
556 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
559 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
560 <div class="directive-section"><h2><a name="AllowOverrideList" id="AllowOverrideList">AllowOverrideList</a> <a name="allowoverridelist" id="allowoverridelist">Directive</a></h2>
561 <table class="directive">
562 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Individual directives that are allowed in
563 <code>.htaccess</code> files</td></tr>
564 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverrideList None|<var>directive</var>
565 [<var>directive-type</var>] ...</code></td></tr>
566 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowOverrideList None</code></td></tr>
567 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
568 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
569 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
571 <p>When the server finds an <code>.htaccess</code> file (as
572 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>),
573 it needs to know which directives declared in that file can override
574 earlier configuration directives.</p>
576 <div class="note"><h3>Only available in <Directory> sections</h3>
577 <code class="directive">AllowOverrideList</code> is valid only in
578 <code class="directive"><a href="#directory"><Directory></a></code>
579 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
580 <code class="directive"><a href="#files"><Files></a></code> sections.
583 <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>,
584 then <a href="#accessfilename">.htaccess</a> files are completely
585 ignored. In this case, the server will not even attempt to read
586 <code>.htaccess</code> files in the filesystem.</p>
590 <pre class="prettyprint lang-config">AllowOverride None
591 AllowOverrideList Redirect RedirectMatch</pre>
594 <p>In the example above, only the <code>Redirect</code> and
595 <code>RedirectMatch</code> directives are allowed. All others will
596 cause an Internal Server Error.</p>
600 <pre class="prettyprint lang-config">AllowOverride AuthConfig
601 AllowOverrideList CookieTracking CookieName</pre>
604 <p>In the example above, <code class="directive"><a href="#allowoverride">AllowOverride
605 </a></code> grants permission to the <code>AuthConfig</code>
606 directive grouping and <code class="directive">AllowOverrideList</code> grants
607 permission to only two directives from the <code>FileInfo</code> directive
608 grouping. All others will cause an Internal Server Error.</p>
612 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
613 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
614 <li><a href="../configuring.html">Configuration Files</a></li>
615 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
618 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
619 <div class="directive-section"><h2><a name="AsyncFilter" id="AsyncFilter">AsyncFilter</a> <a name="asyncfilter" id="asyncfilter">Directive</a></h2>
620 <table class="directive">
621 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Set the minimum filter type eligible for asynchronous handling</td></tr>
622 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AsyncFilter request|connection|network</code></td></tr>
623 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AsyncFilter request</code></td></tr>
624 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
625 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
626 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
627 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.5.0 and later.</td></tr>
629 <p>This directive controls the minimum filter levels that are eligible
630 for asynchronous handling. This may be necessary to support legacy external
631 filters that did not handle meta buckets correctly.</p>
633 <p>If set to "network", asynchronous handling will be limited to the network
634 filter only. If set to "connection", all connection and network filters
635 will be eligible for asynchronous handling, including <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code>.
636 If set to "request", all filters will be eligible for asynchronous handling.</p>
639 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
640 <div class="directive-section"><h2><a name="CGIMapExtension" id="CGIMapExtension">CGIMapExtension</a> <a name="cgimapextension" id="cgimapextension">Directive</a></h2>
641 <table class="directive">
642 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
644 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIMapExtension <var>cgi-path</var> <var>.extension</var></code></td></tr>
645 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
646 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
647 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
648 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
649 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>NetWare only</td></tr>
651 <p>This directive is used to control how Apache httpd finds the
652 interpreter used to run CGI scripts. For example, setting
653 <code>CGIMapExtension sys:\foo.nlm .foo</code> will
654 cause all CGI script files with a <code>.foo</code> extension to
655 be passed to the FOO interpreter.</p>
658 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
659 <div class="directive-section"><h2><a name="CGIPassAuth" id="CGIPassAuth">CGIPassAuth</a> <a name="cgipassauth" id="cgipassauth">Directive</a></h2>
660 <table class="directive">
661 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables passing HTTP authorization headers to scripts as CGI
663 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIPassAuth On|Off</code></td></tr>
664 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CGIPassAuth Off</code></td></tr>
665 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
666 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig</td></tr>
667 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
668 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
669 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.4.13 and later</td></tr>
671 <p><code class="directive">CGIPassAuth</code> allows scripts access to HTTP
672 authorization headers such as <code>Authorization</code>, which is
673 required for scripts that implement HTTP Basic authentication.
674 Normally these HTTP headers are hidden from scripts. This is to disallow
675 scripts from seeing user ids and passwords used to access the server when
676 HTTP Basic authentication is enabled in the web server. This directive
677 should be used when scripts are allowed to implement HTTP Basic
680 <p>This directive can be used instead of the compile-time setting
681 <code>SECURITY_HOLE_PASS_AUTHORIZATION</code> which has been available
682 in previous versions of Apache HTTP Server.</p>
684 <p>The setting is respected by any modules which use
685 <code>ap_add_common_vars()</code>, such as <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>,
686 <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>,
687 <code class="module"><a href="../mod/mod_proxy_scgi.html">mod_proxy_scgi</a></code>, and so on. Notably, it affects
688 modules which don't handle the request in the usual sense but
689 still use this API; examples of this are <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
690 and <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>. Third-party modules that don't
691 use <code>ap_add_common_vars()</code> may choose to respect the setting
695 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
696 <div class="directive-section"><h2><a name="CGIVar" id="CGIVar">CGIVar</a> <a name="cgivar" id="cgivar">Directive</a></h2>
697 <table class="directive">
698 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls how some CGI variables are set</td></tr>
699 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIVar <var>variable</var> <var>rule</var></code></td></tr>
700 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
701 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
702 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
703 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
704 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.5 and later</td></tr>
706 <p>This directive controls how some CGI variables are set.</p>
708 <p><strong>REQUEST_URI</strong> rules:</p>
710 <dt><code>original-uri</code> (default)</dt>
711 <dd>The value is taken from the original request line, and will not
712 reflect internal redirects or subrequests which change the requested
714 <dt><code>current-uri</code></dt>
715 <dd>The value reflects the resource currently being processed,
716 which may be different than the original request from the client
717 due to internal redirects or subrequests.</dd>
721 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
722 <div class="directive-section"><h2><a name="ContentDigest" id="ContentDigest">ContentDigest</a> <a name="contentdigest" id="contentdigest">Directive</a></h2>
723 <table class="directive">
724 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables the generation of <code>Content-MD5</code> HTTP Response
726 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ContentDigest On|Off</code></td></tr>
727 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ContentDigest Off</code></td></tr>
728 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
729 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
730 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
731 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
733 <p>This directive enables the generation of
734 <code>Content-MD5</code> headers as defined in RFC1864
735 respectively RFC2616.</p>
737 <p>MD5 is an algorithm for computing a "message digest"
738 (sometimes called "fingerprint") of arbitrary-length data, with
739 a high degree of confidence that any alterations in the data
740 will be reflected in alterations in the message digest.</p>
742 <p>The <code>Content-MD5</code> header provides an end-to-end
743 message integrity check (MIC) of the entity-body. A proxy or
744 client may check this header for detecting accidental
745 modification of the entity-body in transit. Example header:</p>
747 <div class="example"><p><code>
748 Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
751 <p>Note that this can cause performance problems on your server
752 since the message digest is computed on every request (the
753 values are not cached).</p>
755 <p><code>Content-MD5</code> is only sent for documents served
756 by the <code class="module"><a href="../mod/core.html">core</a></code>, and not by any module. For example,
757 SSI documents, output from CGI scripts, and byte range responses
758 do not have this header.</p>
761 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
762 <div class="directive-section"><h2><a name="DefaultRuntimeDir" id="DefaultRuntimeDir">DefaultRuntimeDir</a> <a name="defaultruntimedir" id="defaultruntimedir">Directive</a></h2>
763 <table class="directive">
764 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server run-time files</td></tr>
765 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultRuntimeDir <var>directory-path</var></code></td></tr>
766 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultRuntimeDir DEFAULT_REL_RUNTIMEDIR (logs/)</code></td></tr>
767 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
768 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
769 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
770 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.4.2 and later</td></tr>
772 <p>The <code class="directive">DefaultRuntimeDir</code> directive sets the
773 directory in which the server will create various run-time files
774 (shared memory, locks, etc.). If set as a relative path, the full path
775 will be relative to <code class="directive">ServerRoot</code>.</p>
777 <p><strong>Example</strong></p>
778 <pre class="prettyprint lang-config">DefaultRuntimeDir scratch/</pre>
781 <p>The default location of <code class="directive">DefaultRuntimeDir</code> may be
782 modified by changing the <code>DEFAULT_REL_RUNTIMEDIR</code> #define
785 <p>Note: <code class="directive">ServerRoot</code> should be specified before this
786 directive is used. Otherwise, the default value of <code class="directive">ServerRoot</code>
787 would be used to set the base directory.</p>
792 <li><a href="../misc/security_tips.html#serverroot">the
793 security tips</a> for information on how to properly set
794 permissions on the <code class="directive">ServerRoot</code></li>
797 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
798 <div class="directive-section"><h2><a name="DefaultType" id="DefaultType">DefaultType</a> <a name="defaulttype" id="defaulttype">Directive</a></h2>
799 <table class="directive">
800 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>This directive has no effect other than to emit warnings
801 if the value is not <code>none</code>. In prior versions, DefaultType
802 would specify a default media type to assign to response content for
803 which no other media type configuration could be found.
805 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultType <var>media-type|none</var></code></td></tr>
806 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultType none</code></td></tr>
807 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
808 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
809 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
810 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
811 <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.
814 <p>This directive has been disabled. For backwards compatibility
815 of configuration files, it may be specified with the value
816 <code>none</code>, meaning no default media type. For example:</p>
818 <pre class="prettyprint lang-config">DefaultType None</pre>
821 <p><code>DefaultType None</code> is only available in
822 httpd-2.2.7 and later.</p>
824 <p>Use the mime.types configuration file and the
825 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code> to configure media
826 type assignments via file extensions, or the
827 <code class="directive"><a href="#forcetype">ForceType</a></code> directive to configure
828 the media type for specific resources. Otherwise, the server will
829 send the response without a Content-Type header field and the
830 recipient may attempt to guess the media type.</p>
833 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
834 <div class="directive-section"><h2><a name="Define" id="Define">Define</a> <a name="define" id="define">Directive</a></h2>
835 <table class="directive">
836 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Define a variable</td></tr>
837 <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>
838 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
839 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
840 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
842 <p>In its one parameter form, <code class="directive">Define</code> is equivalent
843 to passing the <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>. It
844 can be used to toggle the use of
845 <code class="directive"><a href="#ifdefine"><IfDefine></a></code> sections
846 without needing to alter <code>-D</code> arguments in any startup
849 <p>In addition to that, if the second parameter is given, a config variable
850 is set to this value. The variable can be used in the configuration using
851 the <code>${VAR}</code> syntax. The variable is always globally defined
852 and not limited to the scope of the surrounding config section.</p>
854 <pre class="prettyprint lang-config"><IfDefine TEST>
855 Define servername test.example.com
857 <IfDefine !TEST>
858 Define servername www.example.com
862 DocumentRoot "/var/www/${servername}/htdocs"</pre>
865 <p>Variable names may not contain colon ":" characters, to avoid clashes
866 with <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>'s syntax.</p>
868 <p>While this directive is supported in virtual host context,
869 the changes it makes are visible to any later configuration
870 directives, beyond any enclosing virtual host</p>
873 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
874 <div class="directive-section"><h2><a name="Directory" id="Directory"><Directory></a> <a name="directory" id="directory">Directive</a></h2>
875 <table class="directive">
876 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose a group of directives that apply only to the
877 named file-system directory, sub-directories, and their contents.</td></tr>
878 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Directory <var>directory-path</var>>
879 ... </Directory></code></td></tr>
880 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
881 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
882 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
884 <p><code class="directive"><Directory></code> and
885 <code></Directory></code> are used to enclose a group of
886 directives that will apply only to the named directory,
887 sub-directories of that directory, and the files within the respective
888 directories. Any directive that is allowed
889 in a directory context may be used. <var>Directory-path</var> is
890 either the full path to a directory, or a wild-card string using
891 Unix shell-style matching. In a wild-card string, <code>?</code> matches
892 any single character, and <code>*</code> matches any sequences of
893 characters. You may also use <code>[]</code> character ranges. None
894 of the wildcards match a `/' character, so <code><Directory
895 "/*/public_html"></code> will not match
896 <code>/home/user/public_html</code>, but <code><Directory
897 "/home/*/public_html"></code> will match. Example:</p>
899 <pre class="prettyprint lang-config"><Directory "/usr/local/httpd/htdocs">
900 Options Indexes FollowSymLinks
901 </Directory></pre>
904 <p>Directory paths <em>may</em> be quoted, if you like, however, it
905 <em>must</em> be quoted if the path contains spaces. This is because a
906 space would otherwise indicate the end of an argument.</p>
909 <p>Be careful with the <var>directory-path</var> arguments:
910 They have to literally match the filesystem path which Apache httpd uses
911 to access the files. Directives applied to a particular
912 <code><Directory></code> will not apply to files accessed from
913 that same directory via a different path, such as via different symbolic
917 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular
918 expressions</a> can also be used, with the addition of the
919 <code>~</code> character. For example:</p>
921 <pre class="prettyprint lang-config"><Directory ~ "^/www/[0-9]{3}">
923 </Directory></pre>
926 <p>would match directories in <code>/www/</code> that consisted of
929 <p>If multiple (non-regular expression) <code class="directive"><Directory></code> sections
930 match the directory (or one of its parents) containing a document,
931 then the directives are applied in the order of shortest match
932 first, interspersed with the directives from the <a href="#accessfilename">.htaccess</a> files. For example,
935 <pre class="prettyprint lang-config"><Directory "/">
939 <Directory "/home">
940 AllowOverride FileInfo
941 </Directory></pre>
944 <p>for access to the document <code>/home/web/dir/doc.html</code>
948 <li>Apply directive <code>AllowOverride None</code>
949 (disabling <code>.htaccess</code> files).</li>
951 <li>Apply directive <code>AllowOverride FileInfo</code> (for
952 directory <code>/home</code>).</li>
954 <li>Apply any <code>FileInfo</code> directives in
955 <code>/home/.htaccess</code>, <code>/home/web/.htaccess</code> and
956 <code>/home/web/dir/.htaccess</code> in that order.</li>
959 <p>Regular expressions are not considered until after all of the
960 normal sections have been applied. Then all of the regular
961 expressions are tested in the order they appeared in the
962 configuration file. For example, with</p>
964 <pre class="prettyprint lang-config"><Directory ~ "abc$">
965 # ... directives here ...
966 </Directory></pre>
969 <p>the regular expression section won't be considered until after
970 all normal <code class="directive"><Directory></code>s and
971 <code>.htaccess</code> files have been applied. Then the regular
972 expression will match on <code>/home/abc/public_html/abc</code> and
973 the corresponding <code class="directive"><Directory></code> will
976 <p><strong>Note that the default access for
977 <code><Directory "/"></code> is to permit all access.
978 This means that Apache httpd will serve any file mapped from an URL. It is
979 recommended that you change this with a block such
982 <pre class="prettyprint lang-config"><Directory "/">
984 </Directory></pre>
987 <p><strong>and then override this for directories you
988 <em>want</em> accessible. See the <a href="../misc/security_tips.html">Security Tips</a> page for more
989 details.</strong></p>
991 <p>The directory sections occur in the <code>httpd.conf</code> file.
992 <code class="directive"><Directory></code> directives
993 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>
997 <li><a href="../sections.html">How <Directory>,
998 <Location> and <Files> sections work</a> for an
999 explanation of how these different sections are combined when a
1000 request is received</li>
1003 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1004 <div class="directive-section"><h2><a name="DirectoryMatch" id="DirectoryMatch"><DirectoryMatch></a> <a name="directorymatch" id="directorymatch">Directive</a></h2>
1005 <table class="directive">
1006 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose directives that apply to
1007 the contents of file-system directories matching a regular expression.</td></tr>
1008 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><DirectoryMatch <var>regex</var>>
1009 ... </DirectoryMatch></code></td></tr>
1010 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1011 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1012 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1014 <p><code class="directive"><DirectoryMatch></code> and
1015 <code></DirectoryMatch></code> are used to enclose a group
1016 of directives which will apply only to the named directory (and the files within),
1017 the same as <code class="directive"><a href="#directory"><Directory></a></code>.
1018 However, it takes as an argument a
1019 <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>. For example:</p>
1021 <pre class="prettyprint lang-config"><DirectoryMatch "^/www/(.+/)?[0-9]{3}/">
1023 </DirectoryMatch></pre>
1026 <p>matches directories in <code>/www/</code> (or any subdirectory thereof)
1027 that consist of three numbers.</p>
1029 <div class="note"><h3>Compatability</h3>
1030 Prior to 2.3.9, this directive implicitly applied to sub-directories
1031 (like <code class="directive"><a href="#directory"><Directory></a></code>) and
1032 could not match the end of line symbol ($). In 2.3.9 and later,
1033 only directories that match the expression are affected by the enclosed
1037 <div class="note"><h3>Trailing Slash</h3>
1038 This directive applies to requests for directories that may or may
1039 not end in a trailing slash, so expressions that are anchored to the
1040 end of line ($) must be written with care.
1043 <p>From 2.4.8 onwards, named groups and backreferences are captured and
1044 written to the environment with the corresponding name prefixed with
1045 "MATCH_" and in upper case. This allows elements of paths to be referenced
1046 from within <a href="../expr.html">expressions</a> and modules like
1047 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
1048 (unnamed) backreferences are ignored. Use named groups instead.</p>
1050 <pre class="prettyprint lang-config"><DirectoryMatch "^/var/www/combined/(?<sitename>[^/]+)">
1051 Require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
1052 </DirectoryMatch></pre>
1057 <li><code class="directive"><a href="#directory"><Directory></a></code> for
1058 a description of how regular expressions are mixed in with normal
1059 <code class="directive"><Directory></code>s</li>
1060 <li><a href="../sections.html">How <Directory>, <Location> and
1061 <Files> sections work</a> for an explanation of how these different
1062 sections are combined when a request is received</li>
1065 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1066 <div class="directive-section"><h2><a name="DocumentRoot" id="DocumentRoot">DocumentRoot</a> <a name="documentroot" id="documentroot">Directive</a></h2>
1067 <table class="directive">
1068 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory that forms the main document tree visible
1069 from the web</td></tr>
1070 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DocumentRoot <var>directory-path</var></code></td></tr>
1071 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DocumentRoot /usr/local/apache/htdocs</code></td></tr>
1072 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1073 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1074 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1076 <p>This directive sets the directory from which <code class="program"><a href="../programs/httpd.html">httpd</a></code>
1077 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
1078 path from the requested URL to the document root to make the
1079 path to the document. Example:</p>
1081 <pre class="prettyprint lang-config">DocumentRoot "/usr/web"</pre>
1084 <p>then an access to
1085 <code>http://my.example.com/index.html</code> refers to
1086 <code>/usr/web/index.html</code>. If the <var>directory-path</var> is
1087 not absolute then it is assumed to be relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1089 <p>The <code class="directive">DocumentRoot</code> should be specified without
1090 a trailing slash.</p>
1094 <li><a href="../urlmapping.html#documentroot">Mapping URLs to Filesystem
1098 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1099 <div class="directive-section"><h2><a name="Else" id="Else"><Else></a> <a name="else" id="else">Directive</a></h2>
1100 <table class="directive">
1101 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if the condition of a
1102 previous <code class="directive"><a href="#if"><If></a></code> or
1103 <code class="directive"><a href="#elseif"><ElseIf></a></code> section is not
1104 satisfied by a request at runtime</td></tr>
1105 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Else> ... </Else></code></td></tr>
1106 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1107 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1108 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1109 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1111 <p>The <code class="directive"><Else></code> applies the enclosed
1112 directives if and only if the most recent
1113 <code class="directive"><If></code> or
1114 <code class="directive"><ElseIf></code> section
1115 in the same scope has not been applied.
1116 For example: In </p>
1118 <pre class="prettyprint lang-config"><If "-z req('Host')">
1126 <p> The <code class="directive"><If></code> would match HTTP/1.0
1127 requests without a <var>Host:</var> header and the
1128 <code class="directive"><Else></code> would match requests
1129 with a <var>Host:</var> header.</p>
1134 <li><code class="directive"><a href="#if"><If></a></code></li>
1135 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
1136 <li><a href="../sections.html">How <Directory>, <Location>,
1137 <Files> sections work</a> for an explanation of how these
1138 different sections are combined when a request is received.
1139 <code class="directive"><If></code>,
1140 <code class="directive"><ElseIf></code>, and
1141 <code class="directive"><Else></code> are applied last.</li>
1144 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1145 <div class="directive-section"><h2><a name="ElseIf" id="ElseIf"><ElseIf></a> <a name="elseif" id="elseif">Directive</a></h2>
1146 <table class="directive">
1147 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is satisfied
1148 by a request at runtime while the condition of a previous
1149 <code class="directive"><a href="#if"><If></a></code> or
1150 <code class="directive"><ElseIf></code> section is not
1152 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><ElseIf <var>expression</var>> ... </ElseIf></code></td></tr>
1153 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1154 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1155 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1156 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1158 <p>The <code class="directive"><ElseIf></code> applies the enclosed
1159 directives if and only if both the given condition evaluates to true and
1160 the most recent <code class="directive"><If></code> or
1161 <code class="directive"><ElseIf></code> section in the same scope has
1162 not been applied. For example: In </p>
1164 <pre class="prettyprint lang-config"><If "-R '10.1.0.0/16'">
1167 <ElseIf "-R '10.0.0.0/8'">
1175 <p>The <code class="directive"><ElseIf></code> would match if
1176 the remote address of a request belongs to the subnet 10.0.0.0/8 but
1177 not to the subnet 10.1.0.0/16.</p>
1182 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
1183 for a complete reference and more examples.</li>
1184 <li><code class="directive"><a href="#if"><If></a></code></li>
1185 <li><code class="directive"><a href="#else"><Else></a></code></li>
1186 <li><a href="../sections.html">How <Directory>, <Location>,
1187 <Files> sections work</a> for an explanation of how these
1188 different sections are combined when a request is received.
1189 <code class="directive"><If></code>,
1190 <code class="directive"><ElseIf></code>, and
1191 <code class="directive"><Else></code> are applied last.</li>
1194 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1195 <div class="directive-section"><h2><a name="EnableMMAP" id="EnableMMAP">EnableMMAP</a> <a name="enablemmap" id="enablemmap">Directive</a></h2>
1196 <table class="directive">
1197 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use memory-mapping to read files during delivery</td></tr>
1198 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableMMAP On|Off</code></td></tr>
1199 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableMMAP On</code></td></tr>
1200 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1201 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1202 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1203 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1205 <p>This directive controls whether the <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use
1206 memory-mapping if it needs to read the contents of a file during
1207 delivery. By default, when the handling of a request requires
1208 access to the data within a file -- for example, when delivering a
1209 server-parsed file using <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> -- Apache httpd
1210 memory-maps the file if the OS supports it.</p>
1212 <p>This memory-mapping sometimes yields a performance improvement.
1213 But in some environments, it is better to disable the memory-mapping
1214 to prevent operational problems:</p>
1217 <li>On some multiprocessor systems, memory-mapping can reduce the
1218 performance of the <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</li>
1219 <li>Deleting or truncating a file while <code class="program"><a href="../programs/httpd.html">httpd</a></code>
1220 has it memory-mapped can cause <code class="program"><a href="../programs/httpd.html">httpd</a></code> to
1221 crash with a segmentation fault.
1225 <p>For server configurations that are vulnerable to these problems,
1226 you should disable memory-mapping of delivered files by specifying:</p>
1228 <pre class="prettyprint lang-config">EnableMMAP Off</pre>
1231 <p>For NFS mounted files, this feature may be disabled explicitly for
1232 the offending files by specifying:</p>
1234 <pre class="prettyprint lang-config"><Directory "/path-to-nfs-files">
1236 </Directory></pre>
1240 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1241 <div class="directive-section"><h2><a name="EnableSendfile" id="EnableSendfile">EnableSendfile</a> <a name="enablesendfile" id="enablesendfile">Directive</a></h2>
1242 <table class="directive">
1243 <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>
1244 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableSendfile On|Off</code></td></tr>
1245 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableSendfile Off</code></td></tr>
1246 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1247 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1248 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1249 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1250 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Default changed to Off in
1251 version 2.3.9.</td></tr>
1253 <p>This directive controls whether <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use the
1254 sendfile support from the kernel to transmit file contents to the client.
1255 By default, when the handling of a request requires no access
1256 to the data within a file -- for example, when delivering a
1257 static file -- Apache httpd uses sendfile to deliver the file contents
1258 without ever reading the file if the OS supports it.</p>
1260 <p>This sendfile mechanism avoids separate read and send operations,
1261 and buffer allocations. But on some platforms or within some
1262 filesystems, it is better to disable this feature to avoid
1263 operational problems:</p>
1266 <li>Some platforms may have broken sendfile support that the build
1267 system did not detect, especially if the binaries were built on
1268 another box and moved to such a machine with broken sendfile
1270 <li>On Linux the use of sendfile triggers TCP-checksum
1271 offloading bugs on certain networking cards when using IPv6.</li>
1272 <li>On Linux on Itanium, <code>sendfile</code> may be unable to handle
1273 files over 2GB in size.</li>
1274 <li>With a network-mounted <code class="directive"><a href="#documentroot">DocumentRoot</a></code> (e.g., NFS, SMB, CIFS, FUSE),
1275 the kernel may be unable to serve the network file through
1279 <p>For server configurations that are not vulnerable to these problems,
1280 you may enable this feature by specifying:</p>
1282 <pre class="prettyprint lang-config">EnableSendfile On</pre>
1285 <p>For network mounted files, this feature may be disabled explicitly
1286 for the offending files by specifying:</p>
1288 <pre class="prettyprint lang-config"><Directory "/path-to-nfs-files">
1290 </Directory></pre>
1292 <p>Please note that the per-directory and .htaccess configuration
1293 of <code class="directive">EnableSendfile</code> is not supported by
1294 <code class="module"><a href="../mod/mod_cache_disk.html">mod_cache_disk</a></code>.
1295 Only global definition of <code class="directive">EnableSendfile</code>
1296 is taken into account by the module.
1300 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1301 <div class="directive-section"><h2><a name="Error" id="Error">Error</a> <a name="error" id="error">Directive</a></h2>
1302 <table class="directive">
1303 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Abort configuration parsing with a custom error message</td></tr>
1304 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Error <var>message</var></code></td></tr>
1305 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1306 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1307 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1308 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.3.9 and later</td></tr>
1310 <p>If an error can be detected within the configuration, this
1311 directive can be used to generate a custom error message, and halt
1312 configuration parsing. The typical use is for reporting required
1313 modules which are missing from the configuration.</p>
1315 <pre class="prettyprint lang-config"># Example
1316 # ensure that mod_include is loaded
1317 <IfModule !include_module>
1318 Error "mod_include is required by mod_foo. Load it with LoadModule."
1321 # ensure that exactly one of SSL,NOSSL is defined
1322 <IfDefine SSL>
1323 <IfDefine NOSSL>
1324 Error "Both SSL and NOSSL are defined. Define only one of them."
1327 <IfDefine !SSL>
1328 <IfDefine !NOSSL>
1329 Error "Either SSL or NOSSL must be defined."
1331 </IfDefine></pre>
1336 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1337 <div class="directive-section"><h2><a name="ErrorDocument" id="ErrorDocument">ErrorDocument</a> <a name="errordocument" id="errordocument">Directive</a></h2>
1338 <table class="directive">
1339 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>What the server will return to the client
1340 in case of an error</td></tr>
1341 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ErrorDocument <var>error-code</var> <var>document</var></code></td></tr>
1342 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1343 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1344 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1345 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1347 <p>In the event of a problem or error, Apache httpd can be configured
1348 to do one of four things,</p>
1351 <li>output a simple hardcoded error message</li>
1353 <li>output a customized message</li>
1355 <li>internally redirect to a local <var>URL-path</var> to handle the
1358 <li>redirect to an external <var>URL</var> to handle the
1362 <p>The first option is the default, while options 2-4 are
1363 configured using the <code class="directive">ErrorDocument</code>
1364 directive, which is followed by the HTTP response code and a URL
1365 or a message. Apache httpd will sometimes offer additional information
1366 regarding the problem/error.</p>
1368 <p>From 2.4.13, <a href="../expr.html">expression syntax</a> can be
1369 used inside the directive to produce dynamic strings and URLs.</p>
1371 <p>URLs can begin with a slash (/) for local web-paths (relative
1372 to the <code class="directive"><a href="#documentroot">DocumentRoot</a></code>), or be a
1373 full URL which the client can resolve. Alternatively, a message
1374 can be provided to be displayed by the browser. Note that deciding
1375 whether the parameter is an URL, a path or a message is performed
1376 before any expression is parsed. Examples:</p>
1378 <pre class="prettyprint lang-config">ErrorDocument 500 http://example.com/cgi-bin/server-error.cgi
1379 ErrorDocument 404 /errors/bad_urls.php
1380 ErrorDocument 401 /subscription_info.html
1381 ErrorDocument 403 "Sorry, can't allow you access today"
1382 ErrorDocument 403 Forbidden!
1383 ErrorDocument 403 /errors/forbidden.py?referrer=%{escape:%{HTTP_REFERER}}</pre>
1386 <p>Additionally, the special value <code>default</code> can be used
1387 to specify Apache httpd's simple hardcoded message. While not required
1388 under normal circumstances, <code>default</code> will restore
1389 Apache httpd's simple hardcoded message for configurations that would
1390 otherwise inherit an existing <code class="directive">ErrorDocument</code>.</p>
1392 <pre class="prettyprint lang-config">ErrorDocument 404 /cgi-bin/bad_urls.pl
1394 <Directory "/web/docs">
1395 ErrorDocument 404 default
1396 </Directory></pre>
1399 <p>Note that when you specify an <code class="directive">ErrorDocument</code>
1400 that points to a remote URL (ie. anything with a method such as
1401 <code>http</code> in front of it), Apache HTTP Server will send a redirect to the
1402 client to tell it where to find the document, even if the
1403 document ends up being on the same server. This has several
1404 implications, the most important being that the client will not
1405 receive the original error status code, but instead will
1406 receive a redirect status code. This in turn can confuse web
1407 robots and other clients which try to determine if a URL is
1408 valid using the status code. In addition, if you use a remote
1409 URL in an <code>ErrorDocument 401</code>, the client will not
1410 know to prompt the user for a password since it will not
1411 receive the 401 status code. Therefore, <strong>if you use an
1412 <code>ErrorDocument 401</code> directive, then it must refer to a local
1413 document.</strong></p>
1415 <p>Microsoft Internet Explorer (MSIE) will by default ignore
1416 server-generated error messages when they are "too small" and substitute
1417 its own "friendly" error messages. The size threshold varies depending on
1418 the type of error, but in general, if you make your error document
1419 greater than 512 bytes, then MSIE will show the server-generated
1420 error rather than masking it. More information is available in
1421 Microsoft Knowledge Base article <a href="http://support.microsoft.com/default.aspx?scid=kb;en-us;Q294807">Q294807</a>.</p>
1423 <p>Although most error messages can be overridden, there are certain
1424 circumstances where the internal messages are used regardless of the
1425 setting of <code class="directive"><a href="#errordocument">ErrorDocument</a></code>. In
1426 particular, if a malformed request is detected, normal request processing
1427 will be immediately halted and the internal error message returned.
1428 This is necessary to guard against security problems caused by
1431 <p>If you are using mod_proxy, you may wish to enable
1432 <code class="directive"><a href="../mod/mod_proxy.html#proxyerroroverride">ProxyErrorOverride</a></code> so that you can provide
1433 custom error messages on behalf of your Origin servers. If you don't enable ProxyErrorOverride,
1434 Apache httpd will not generate custom error documents for proxied content.</p>
1438 <li><a href="../custom-error.html">documentation of
1439 customizable responses</a></li>
1442 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1443 <div class="directive-section"><h2><a name="ErrorLog" id="ErrorLog">ErrorLog</a> <a name="errorlog" id="errorlog">Directive</a></h2>
1444 <table class="directive">
1445 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Location where the server will log errors</td></tr>
1446 <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>
1447 <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>
1448 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1449 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1450 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1452 <p>The <code class="directive">ErrorLog</code> directive sets the name of
1453 the file to which the server will log any errors it encounters. If
1454 the <var>file-path</var> is not absolute then it is assumed to be
1455 relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1457 <pre class="prettyprint lang-config">ErrorLog "/var/log/httpd/error_log"</pre>
1460 <p>If the <var>file-path</var>
1461 begins with a pipe character "<code>|</code>" then it is assumed to be a
1462 command to spawn to handle the error log.</p>
1464 <pre class="prettyprint lang-config">ErrorLog "|/usr/local/bin/httpd_errors"</pre>
1467 <p>See the notes on <a href="../logs.html#piped">piped logs</a> for
1468 more information.</p>
1470 <p>Using <code>syslog</code> instead of a filename enables logging
1471 via syslogd(8) if the system supports it and if <code class="module"><a href="../mod/mod_syslog.html">mod_syslog</a></code>
1472 is loaded. The default is to use syslog facility <code>local7</code>,
1473 but you can override this by using the <code>syslog:<var>facility</var></code>
1474 syntax where <var>facility</var> can be one of the names usually documented in
1475 syslog(1). The facility is effectively global, and if it is changed
1476 in individual virtual hosts, the final facility specified affects the
1479 <pre class="prettyprint lang-config">ErrorLog syslog:user</pre>
1482 <p>Additional modules can provide their own ErrorLog providers. The syntax
1483 is similar to the <code>syslog</code> example above.</p>
1485 <p>SECURITY: See the <a href="../misc/security_tips.html#serverroot">security tips</a>
1486 document for details on why your security could be compromised
1487 if the directory where log files are stored is writable by
1488 anyone other than the user that starts the server.</p>
1489 <div class="warning"><h3>Note</h3>
1490 <p>When entering a file path on non-Unix platforms, care should be taken
1491 to make sure that only forward slashes are used even though the platform
1492 may allow the use of back slashes. In general it is a good idea to always
1493 use forward slashes throughout the configuration files.</p>
1498 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1499 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1502 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1503 <div class="directive-section"><h2><a name="ErrorLogFormat" id="ErrorLogFormat">ErrorLogFormat</a> <a name="errorlogformat" id="errorlogformat">Directive</a></h2>
1504 <table class="directive">
1505 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Format specification for error log entries</td></tr>
1506 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code> ErrorLogFormat [connection|request] <var>format</var></code></td></tr>
1507 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1508 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1509 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1511 <p><code class="directive">ErrorLogFormat</code> allows to specify what
1512 supplementary information is logged in the error log in addition to the
1513 actual log message.</p>
1515 <pre class="prettyprint lang-config">#Simple example
1516 ErrorLogFormat "[%t] [%l] [pid %P] %F: %E: [client %a] %M"</pre>
1519 <p>Specifying <code>connection</code> or <code>request</code> as first
1520 parameter allows to specify additional formats, causing additional
1521 information to be logged when the first message is logged for a specific
1522 connection or request, respectively. This additional information is only
1523 logged once per connection/request. If a connection or request is processed
1524 without causing any log message, the additional information is not logged
1527 <p>It can happen that some format string items do not produce output. For
1528 example, the Referer header is only present if the log message is
1529 associated to a request and the log message happens at a time when the
1530 Referer header has already been read from the client. If no output is
1531 produced, the default behavior is to delete everything from the preceding
1532 space character to the next space character. This means the log line is
1533 implicitly divided into fields on non-whitespace to whitespace transitions.
1534 If a format string item does not produce output, the whole field is
1535 omitted. For example, if the remote address <code>%a</code> in the log
1536 format <code>[%t] [%l] [%a] %M </code> is not available, the surrounding
1537 brackets are not logged either. Space characters can be escaped with a
1538 backslash to prevent them from delimiting a field. The combination '% '
1539 (percent space) is a zero-width field delimiter that does not produce any
1542 <p>The above behavior can be changed by adding modifiers to the format
1543 string item. A <code>-</code> (minus) modifier causes a minus to be logged if the
1544 respective item does not produce any output. In once-per-connection/request
1545 formats, it is also possible to use the <code>+</code> (plus) modifier. If an
1546 item with the plus modifier does not produce any output, the whole line is
1549 <p>A number as modifier can be used to assign a log severity level to a
1550 format item. The item will only be logged if the severity of the log
1551 message is not higher than the specified log severity level. The number can
1552 range from 1 (alert) over 4 (warn) and 7 (debug) to 15 (trace8).</p>
1554 <p>For example, here's what would happen if you added modifiers to
1555 the <code>%{Referer}i</code> token, which logs the
1556 <code>Referer</code> request header.</p>
1558 <table class="bordered"><tr class="header"><th>Modified Token</th><th>Meaning</th></tr>
1560 <td><code>%-{Referer}i</code></td>
1561 <td>Logs a <code>-</code> if <code>Referer</code> is not set.</td>
1564 <td><code>%+{Referer}i</code></td>
1565 <td>Omits the entire line if <code>Referer</code> is not set.</td>
1568 <td><code>%4{Referer}i</code></td>
1569 <td>Logs the <code>Referer</code> only if the log message severity
1570 is higher than 4.</td>
1574 <p>Some format string items accept additional parameters in braces.</p>
1576 <table class="bordered"><tr class="header"><th>Format String</th> <th>Description</th></tr>
1577 <tr><td><code>%%</code></td>
1578 <td>The percent sign</td></tr>
1579 <tr class="odd"><td><code>%a</code></td>
1580 <td>Client IP address and port of the request</td></tr>
1581 <tr><td><code>%{c}a</code></td>
1582 <td>Underlying peer IP address and port of the connection (see the
1583 <code class="module"><a href="../mod/mod_remoteip.html">mod_remoteip</a></code> module)</td></tr>
1584 <tr class="odd"><td><code>%A</code></td>
1585 <td>Local IP-address and port</td></tr>
1586 <tr><td><code>%{<em>name</em>}e</code></td>
1587 <td>Request environment variable <em>name</em></td></tr>
1588 <tr class="odd"><td><code>%E</code></td>
1589 <td>APR/OS error status code and string</td></tr>
1590 <tr><td><code>%F</code></td>
1591 <td>Source file name and line number of the log call</td></tr>
1592 <tr class="odd"><td><code>%{<em>name</em>}i</code></td>
1593 <td>Request header <em>name</em></td></tr>
1594 <tr><td><code>%k</code></td>
1595 <td>Number of keep-alive requests on this connection</td></tr>
1596 <tr class="odd"><td><code>%l</code></td>
1597 <td>Loglevel of the message</td></tr>
1598 <tr><td><code>%L</code></td>
1599 <td>Log ID of the request</td></tr>
1600 <tr class="odd"><td><code>%{c}L</code></td>
1601 <td>Log ID of the connection</td></tr>
1602 <tr><td><code>%{C}L</code></td>
1603 <td>Log ID of the connection if used in connection scope, empty otherwise</td></tr>
1604 <tr class="odd"><td><code>%m</code></td>
1605 <td>Name of the module logging the message</td></tr>
1606 <tr><td><code>%M</code></td>
1607 <td>The actual log message</td></tr>
1608 <tr class="odd"><td><code>%{<em>name</em>}n</code></td>
1609 <td>Request note <em>name</em></td></tr>
1610 <tr><td><code>%P</code></td>
1611 <td>Process ID of current process</td></tr>
1612 <tr class="odd"><td><code>%T</code></td>
1613 <td>Thread ID of current thread</td></tr>
1614 <tr><td><code>%{g}T</code></td>
1615 <td>System unique thread ID of current thread (the same ID as
1616 displayed by e.g. <code>top</code>; currently Linux only)</td></tr>
1617 <tr class="odd"><td><code>%t</code></td>
1618 <td>The current time</td></tr>
1619 <tr><td><code>%{u}t</code></td>
1620 <td>The current time including micro-seconds</td></tr>
1621 <tr class="odd"><td><code>%{cu}t</code></td>
1622 <td>The current time in compact ISO 8601 format, including
1623 micro-seconds</td></tr>
1624 <tr><td><code>%v</code></td>
1625 <td>The canonical <code class="directive"><a href="#servername">ServerName</a></code>
1626 of the current server.</td></tr>
1627 <tr class="odd"><td><code>%V</code></td>
1628 <td>The server name of the server serving the request according to the
1629 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code>
1631 <tr><td><code>\ </code> (backslash space)</td>
1632 <td>Non-field delimiting space</td></tr>
1633 <tr class="odd"><td><code>% </code> (percent space)</td>
1634 <td>Field delimiter (no output)</td></tr>
1637 <p>The log ID format <code>%L</code> produces a unique id for a connection
1638 or request. This can be used to correlate which log lines belong to the
1639 same connection or request, which request happens on which connection.
1640 A <code>%L</code> format string is also available in
1641 <code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code> to allow to correlate access log entries
1642 with error log lines. If <code class="module"><a href="../mod/mod_unique_id.html">mod_unique_id</a></code> is loaded, its
1643 unique id will be used as log ID for requests.</p>
1645 <pre class="prettyprint lang-config">#Example (default format for threaded MPMs)
1646 ErrorLogFormat "[%{u}t] [%-m:%l] [pid %P:tid %T] %7F: %E: [client\ %a] %M% ,\ referer\ %{Referer}i"</pre>
1649 <p>This would result in error messages such as:</p>
1651 <div class="example"><p><code>
1652 [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
1655 <p>Notice that, as discussed above, some fields are omitted
1656 entirely because they are not defined.</p>
1658 <pre class="prettyprint lang-config">#Example (similar to the 2.2.x format)
1659 ErrorLogFormat "[%t] [%l] %7F: %E: [client\ %a] %M% ,\ referer\ %{Referer}i"</pre>
1662 <pre class="prettyprint lang-config">#Advanced example with request/connection log IDs
1663 ErrorLogFormat "[%{uc}t] [%-m:%-l] [R:%L] [C:%{C}L] %7F: %E: %M"
1664 ErrorLogFormat request "[%{uc}t] [R:%L] Request %k on C:%{c}L pid:%P tid:%T"
1665 ErrorLogFormat request "[%{uc}t] [R:%L] UA:'%+{User-Agent}i'"
1666 ErrorLogFormat request "[%{uc}t] [R:%L] Referer:'%+{Referer}i'"
1667 ErrorLogFormat connection "[%{uc}t] [C:%{c}L] local\ %a remote\ %A"</pre>
1673 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
1674 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1675 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1678 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1679 <div class="directive-section"><h2><a name="ExtendedStatus" id="ExtendedStatus">ExtendedStatus</a> <a name="extendedstatus" id="extendedstatus">Directive</a></h2>
1680 <table class="directive">
1681 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Keep track of extended status information for each
1683 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ExtendedStatus On|Off</code></td></tr>
1684 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ExtendedStatus Off[*]</code></td></tr>
1685 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
1686 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1687 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1689 <p>This option tracks additional data per worker about the
1690 currently executing request and creates a utilization summary.
1691 You can see these variables during runtime by configuring
1692 <code class="module"><a href="../mod/mod_status.html">mod_status</a></code>. Note that other modules may
1693 rely on this scoreboard.</p>
1695 <p>This setting applies to the entire server and cannot be
1696 enabled or disabled on a virtualhost-by-virtualhost basis.
1697 The collection of extended status information can slow down
1698 the server. Also note that this setting cannot be changed
1699 during a graceful restart.</p>
1702 <p>Note that loading <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> will change
1703 the default behavior to ExtendedStatus On, while other
1704 third party modules may do the same. Such modules rely on
1705 collecting detailed information about the state of all workers.
1706 The default is changed by <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> beginning
1707 with version 2.3.6. The previous default was always Off.</p>
1712 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1713 <div class="directive-section"><h2><a name="FileETag" id="FileETag">FileETag</a> <a name="fileetag" id="fileetag">Directive</a></h2>
1714 <table class="directive">
1715 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>File attributes used to create the ETag
1716 HTTP response header for static files</td></tr>
1717 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>FileETag <var>component</var> ...</code></td></tr>
1718 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>FileETag MTime Size</code></td></tr>
1719 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1720 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1721 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1722 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1723 <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
1727 The <code class="directive">FileETag</code> directive configures the file
1728 attributes that are used to create the <code>ETag</code> (entity
1729 tag) response header field when the document is based on a static file.
1730 (The <code>ETag</code> value is used in cache management to save
1731 network bandwidth.) The
1732 <code class="directive">FileETag</code> directive allows you to choose
1733 which of these -- if any -- should be used. The recognized keywords are:
1737 <dt><strong>INode</strong></dt>
1738 <dd>The file's i-node number will be included in the calculation</dd>
1739 <dt><strong>MTime</strong></dt>
1740 <dd>The date and time the file was last modified will be included</dd>
1741 <dt><strong>Size</strong></dt>
1742 <dd>The number of bytes in the file will be included</dd>
1743 <dt><strong>All</strong></dt>
1744 <dd>All available fields will be used. This is equivalent to:
1745 <pre class="prettyprint lang-config">FileETag INode MTime Size</pre>
1747 <dt><strong>None</strong></dt>
1748 <dd>If a document is file-based, no <code>ETag</code> field will be
1749 included in the response</dd>
1752 <p>The <code>INode</code>, <code>MTime</code>, and <code>Size</code>
1753 keywords may be prefixed with either <code>+</code> or <code>-</code>,
1754 which allow changes to be made to the default setting inherited
1755 from a broader scope. Any keyword appearing without such a prefix
1756 immediately and completely cancels the inherited setting.</p>
1758 <p>If a directory's configuration includes
1759 <code>FileETag INode MTime Size</code>, and a
1760 subdirectory's includes <code>FileETag -INode</code>,
1761 the setting for that subdirectory (which will be inherited by
1762 any sub-subdirectories that don't override it) will be equivalent to
1763 <code>FileETag MTime Size</code>.</p>
1764 <div class="warning"><h3>Warning</h3>
1765 Do not change the default for directories or locations that have WebDAV
1766 enabled and use <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> as a storage provider.
1767 <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> uses <code>MTime Size</code>
1768 as a fixed format for <code>ETag</code> comparisons on conditional requests.
1769 These conditional requests will break if the <code>ETag</code> format is
1770 changed via <code class="directive">FileETag</code>.
1772 <div class="note"><h3>Server Side Includes</h3>
1773 An ETag is not generated for responses parsed by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
1774 since the response entity can change without a change of the INode, MTime, or Size
1775 of the static file with embedded SSI directives.
1780 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1781 <div class="directive-section"><h2><a name="Files" id="Files"><Files></a> <a name="files" id="files">Directive</a></h2>
1782 <table class="directive">
1783 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to matched
1785 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Files <var>filename</var>> ... </Files></code></td></tr>
1786 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1787 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1788 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1789 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1791 <p>The <code class="directive"><Files></code> directive
1792 limits the scope of the enclosed directives by filename. It is comparable
1793 to the <code class="directive"><a href="#directory"><Directory></a></code>
1794 and <code class="directive"><a href="#location"><Location></a></code>
1795 directives. It should be matched with a <code></Files></code>
1796 directive. The directives given within this section will be applied to
1797 any object with a basename (last component of filename) matching the
1798 specified filename. <code class="directive"><Files></code>
1799 sections are processed in the order they appear in the
1800 configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
1801 <code>.htaccess</code> files are read, but before <code class="directive"><a href="#location"><Location></a></code> sections. Note
1802 that <code class="directive"><Files></code> can be nested
1803 inside <code class="directive"><a href="#directory"><Directory></a></code> sections to restrict the
1804 portion of the filesystem they apply to.</p>
1806 <p>The <var>filename</var> argument should include a filename, or
1807 a wild-card string, where <code>?</code> matches any single character,
1808 and <code>*</code> matches any sequences of characters.</p>
1809 <pre class="prettyprint lang-config"><Files "cat.html">
1810 # Insert stuff that applies to cat.html here
1813 <Files "?at.*">
1814 # This would apply to cat.html, bat.html, hat.php and so on.
1815 </Files></pre>
1817 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
1818 can also be used, with the addition of the
1819 <code>~</code> character. For example:</p>
1821 <pre class="prettyprint lang-config"><Files ~ "\.(gif|jpe?g|png)$">
1823 </Files></pre>
1826 <p>would match most common Internet graphics formats. <code class="directive"><a href="#filesmatch"><FilesMatch></a></code> is preferred,
1829 <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
1830 <code>.htaccess</code> files. This allows users to control access to
1831 their own files, at a file-by-file level.</p>
1836 <li><a href="../sections.html">How <Directory>, <Location>
1837 and <Files> sections work</a> for an explanation of how these
1838 different sections are combined when a request is received</li>
1841 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1842 <div class="directive-section"><h2><a name="FilesMatch" id="FilesMatch"><FilesMatch></a> <a name="filesmatch" id="filesmatch">Directive</a></h2>
1843 <table class="directive">
1844 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to regular-expression matched
1846 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><FilesMatch <var>regex</var>> ... </FilesMatch></code></td></tr>
1847 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1848 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1849 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1850 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1852 <p>The <code class="directive"><FilesMatch></code> directive
1853 limits the scope of the enclosed directives by filename, just as the
1854 <code class="directive"><a href="#files"><Files></a></code> directive
1855 does. However, it accepts a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular
1856 expression</a>. For example:</p>
1858 <pre class="prettyprint lang-config"><FilesMatch ".+\.(gif|jpe?g|png)$">
1860 </FilesMatch></pre>
1863 <p>would match most common Internet graphics formats.</p>
1865 <div class="note">The <code>.+</code> at the start of the regex ensures that
1866 files named <code>.png</code>, or <code>.gif</code>, for example,
1867 are not matched.</div>
1869 <p>From 2.4.8 onwards, named groups and backreferences are captured and
1870 written to the environment with the corresponding name prefixed with
1871 "MATCH_" and in upper case. This allows elements of files to be referenced
1872 from within <a href="../expr.html">expressions</a> and modules like
1873 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
1874 (unnamed) backreferences are ignored. Use named groups instead.</p>
1876 <pre class="prettyprint lang-config"><FilesMatch "^(?<sitename>[^/]+)">
1877 require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
1878 </FilesMatch></pre>
1883 <li><a href="../sections.html">How <Directory>, <Location>
1884 and <Files> sections work</a> for an explanation of how these
1885 different sections are combined when a request is received</li>
1888 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1889 <div class="directive-section"><h2><a name="ForceType" id="ForceType">ForceType</a> <a name="forcetype" id="forcetype">Directive</a></h2>
1890 <table class="directive">
1891 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be served with the specified
1892 media type in the HTTP Content-Type header field</td></tr>
1893 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ForceType <var>media-type</var>|None</code></td></tr>
1894 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
1895 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1896 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1897 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1899 <p>When placed into an <code>.htaccess</code> file or a
1900 <code class="directive"><a href="#directory"><Directory></a></code>, or
1901 <code class="directive"><a href="#location"><Location></a></code> or
1902 <code class="directive"><a href="#files"><Files></a></code>
1903 section, this directive forces all matching files to be served
1904 with the content type identification given by
1905 <var>media-type</var>. For example, if you had a directory full of
1906 GIF files, but did not want to label them all with <code>.gif</code>,
1907 you might want to use:</p>
1909 <pre class="prettyprint lang-config">ForceType image/gif</pre>
1912 <p>Note that this directive overrides other indirect media type
1913 associations defined in mime.types or via the
1914 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code>.</p>
1916 <p>You can also override more general
1917 <code class="directive">ForceType</code> settings
1918 by using the value of <code>None</code>:</p>
1920 <pre class="prettyprint lang-config"># force all files to be image/gif:
1921 <Location "/images">
1925 # but normal mime-type associations here:
1926 <Location "/images/mixed">
1928 </Location></pre>
1931 <p>This directive primarily overrides the content types generated for
1932 static files served out of the filesystem. For resources other than
1933 static files, where the generator of the response typically specifies
1934 a Content-Type, this directive has no effect.</p>
1937 <div class="note"><h3>Note</h3>
1938 <p>If no handler is explicitly set for a request, the specified content
1939 type will also be used as the handler name. </p>
1941 <p>When explicit directives such as
1942 <code class="directive"><a href="#sethandler">SetHandler</a></code> or
1943 <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> do not apply
1944 to the current request, the internal handler name normally set by those
1945 directives is instead set to the content type specified by this directive.
1948 This is a historical behavior that some third-party modules
1949 (such as mod_php) may look for a "synthetic" content type used only to
1950 signal the module to take responsibility for the matching request.
1953 <p>Configurations that rely on such "synthetic" types should be avoided.
1954 Additionally, configurations that restrict access to
1955 <code class="directive"><a href="#sethandler">SetHandler</a></code> or
1956 <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> should
1957 restrict access to this directive as well.</p>
1962 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1963 <div class="directive-section"><h2><a name="GprofDir" id="GprofDir">GprofDir</a> <a name="gprofdir" id="gprofdir">Directive</a></h2>
1964 <table class="directive">
1965 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory to write gmon.out profiling data to. </td></tr>
1966 <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>
1967 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1968 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1969 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1971 <p>When the server has been compiled with gprof profiling support,
1972 <code class="directive">GprofDir</code> causes <code>gmon.out</code> files to
1973 be written to the specified directory when the process exits. If the
1974 argument ends with a percent symbol ('%'), subdirectories are created
1975 for each process id.</p>
1977 <p>This directive currently only works with the <code class="module"><a href="../mod/prefork.html">prefork</a></code>
1981 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1982 <div class="directive-section"><h2><a name="HostnameLookups" id="HostnameLookups">HostnameLookups</a> <a name="hostnamelookups" id="hostnamelookups">Directive</a></h2>
1983 <table class="directive">
1984 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables DNS lookups on client IP addresses</td></tr>
1985 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HostnameLookups On|Off|Double</code></td></tr>
1986 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HostnameLookups Off</code></td></tr>
1987 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1988 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1989 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1991 <p>This directive enables DNS lookups so that host names can be
1992 logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
1993 The value <code>Double</code> refers to doing double-reverse
1994 DNS lookup. That is, after a reverse lookup is performed, a forward
1995 lookup is then performed on that result. At least one of the IP
1996 addresses in the forward lookup must match the original
1997 address. (In "tcpwrappers" terminology this is called
1998 <code>PARANOID</code>.)</p>
2000 <p>Regardless of the setting, when <code class="module"><a href="../mod/mod_authz_host.html">mod_authz_host</a></code> is
2001 used for controlling access by hostname, a double reverse lookup
2002 will be performed. This is necessary for security. Note that the
2003 result of this double-reverse isn't generally available unless you
2004 set <code>HostnameLookups Double</code>. For example, if only
2005 <code>HostnameLookups On</code> and a request is made to an object
2006 that is protected by hostname restrictions, regardless of whether
2007 the double-reverse fails or not, CGIs will still be passed the
2008 single-reverse result in <code>REMOTE_HOST</code>.</p>
2010 <p>The default is <code>Off</code> in order to save the network
2011 traffic for those sites that don't truly need the reverse
2012 lookups done. It is also better for the end users because they
2013 don't have to suffer the extra latency that a lookup entails.
2014 Heavily loaded sites should leave this directive
2015 <code>Off</code>, since DNS lookups can take considerable
2016 amounts of time. The utility <code class="program"><a href="../programs/logresolve.html">logresolve</a></code>, compiled by
2017 default to the <code>bin</code> subdirectory of your installation
2018 directory, can be used to look up host names from logged IP addresses
2021 <p>Finally, if you have <a href="mod_authz_host.html#reqhost">hostname-based Require
2022 directives</a>, a hostname lookup will be performed regardless of
2023 the setting of <code>HostnameLookups</code>.</p>
2026 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2027 <div class="directive-section"><h2><a name="If" id="If"><If></a> <a name="if" id="if">Directive</a></h2>
2028 <table class="directive">
2029 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is
2030 satisfied by a request at runtime</td></tr>
2031 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><If <var>expression</var>> ... </If></code></td></tr>
2032 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2033 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2034 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2035 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2037 <p>The <code class="directive"><If></code> directive
2038 evaluates an expression at runtime, and applies the enclosed
2039 directives if and only if the expression evaluates to true.
2042 <pre class="prettyprint lang-config"><If "-z req('Host')"></pre>
2045 <p>would match HTTP/1.0 requests without a <var>Host:</var> header.
2046 Expressions may contain various shell-like operators for string
2047 comparison (<code>==</code>, <code>!=</code>, <code><</code>, ...),
2048 integer comparison (<code>-eq</code>, <code>-ne</code>, ...),
2049 and others (<code>-n</code>, <code>-z</code>, <code>-f</code>, ...).
2050 It is also possible to use regular expressions, </p>
2052 <pre class="prettyprint lang-config"><If "%{QUERY_STRING} =~ /(delete|commit)=.*?elem/"></pre>
2055 <p>shell-like pattern matches and many other operations. These operations
2056 can be done on request headers (<code>req</code>), environment variables
2057 (<code>env</code>), and a large number of other properties. The full
2058 documentation is available in <a href="../expr.html">Expressions in
2059 Apache HTTP Server</a>.</p>
2061 <p>Only directives that support the <a href="directive-dict.html#Context">directory context</a> can be used within this configuration section.</p>
2063 <div class="warning">
2064 Certain variables, such as <code>CONTENT_TYPE</code> and other
2065 response headers, are set after <If> conditions have already
2066 been evaluated, and so will not be available to use in this
2073 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
2074 for a complete reference and more examples.</li>
2075 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
2076 <li><code class="directive"><a href="#else"><Else></a></code></li>
2077 <li><a href="../sections.html">How <Directory>, <Location>,
2078 <Files> sections work</a> for an explanation of how these
2079 different sections are combined when a request is received.
2080 <code class="directive"><If></code>,
2081 <code class="directive"><ElseIf></code>, and
2082 <code class="directive"><Else></code> are applied last.</li>
2085 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2086 <div class="directive-section"><h2><a name="IfDefine" id="IfDefine"><IfDefine></a> <a name="ifdefine" id="ifdefine">Directive</a></h2>
2087 <table class="directive">
2088 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that will be processed only
2089 if a test is true at startup</td></tr>
2090 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfDefine [!]<var>parameter-name</var>> ...
2091 </IfDefine></code></td></tr>
2092 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2093 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2094 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2095 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2097 <p>The <code><IfDefine <var>test</var>>...</IfDefine>
2098 </code> section is used to mark directives that are conditional. The
2099 directives within an <code class="directive"><IfDefine></code>
2100 section are only processed if the <var>test</var> is true. If <var>
2101 test</var> is false, everything between the start and end markers is
2104 <p>The <var>test</var> in the <code class="directive"><IfDefine></code> section directive can be one of two forms:</p>
2107 <li><var>parameter-name</var></li>
2109 <li><code>!</code><var>parameter-name</var></li>
2112 <p>In the former case, the directives between the start and end
2113 markers are only processed if the parameter named
2114 <var>parameter-name</var> is defined. The second format reverses
2115 the test, and only processes the directives if
2116 <var>parameter-name</var> is <strong>not</strong> defined.</p>
2118 <p>The <var>parameter-name</var> argument is a define as given on the
2119 <code class="program"><a href="../programs/httpd.html">httpd</a></code> command line via <code>-D<var>parameter</var>
2120 </code> at the time the server was started or by the <code class="directive"><a href="#define">Define</a></code> directive.</p>
2122 <p><code class="directive"><IfDefine></code> sections are
2123 nest-able, which can be used to implement simple
2124 multiple-parameter tests. Example:</p>
2126 <div class="example"><p><code>httpd -DReverseProxy -DUseCache -DMemCache ...</code></p></div>
2127 <pre class="prettyprint lang-config"><IfDefine ReverseProxy>
2128 LoadModule proxy_module modules/mod_proxy.so
2129 LoadModule proxy_http_module modules/mod_proxy_http.so
2130 <IfDefine UseCache>
2131 LoadModule cache_module modules/mod_cache.so
2132 <IfDefine MemCache>
2133 LoadModule mem_cache_module modules/mod_mem_cache.so
2135 <IfDefine !MemCache>
2136 LoadModule cache_disk_module modules/mod_cache_disk.so
2139 </IfDefine></pre>
2143 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2144 <div class="directive-section"><h2><a name="IfModule" id="IfModule"><IfModule></a> <a name="ifmodule" id="ifmodule">Directive</a></h2>
2145 <table class="directive">
2146 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that are processed conditional on the
2147 presence or absence of a specific module</td></tr>
2148 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfModule [!]<var>module-file</var>|<var>module-identifier</var>> ...
2149 </IfModule></code></td></tr>
2150 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2151 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2152 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2153 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2155 <p>The <code><IfModule <var>test</var>>...</IfModule></code>
2156 section is used to mark directives that are conditional on the presence of
2157 a specific module. The directives within an <code class="directive"><IfModule></code> section are only processed if the <var>test</var>
2158 is true. If <var>test</var> is false, everything between the start and
2159 end markers is ignored.</p>
2161 <p>The <var>test</var> in the <code class="directive"><IfModule></code> section directive can be one of two forms:</p>
2164 <li><var>module</var></li>
2166 <li>!<var>module</var></li>
2169 <p>In the former case, the directives between the start and end
2170 markers are only processed if the module named <var>module</var>
2171 is included in Apache httpd -- either compiled in or
2172 dynamically loaded using <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code>. The second format reverses the test,
2173 and only processes the directives if <var>module</var> is
2174 <strong>not</strong> included.</p>
2176 <p>The <var>module</var> argument can be either the module identifier or
2177 the file name of the module, at the time it was compiled. For example,
2178 <code>rewrite_module</code> is the identifier and
2179 <code>mod_rewrite.c</code> is the file name. If a module consists of
2180 several source files, use the name of the file containing the string
2181 <code>STANDARD20_MODULE_STUFF</code>.</p>
2183 <p><code class="directive"><IfModule></code> sections are
2184 nest-able, which can be used to implement simple multiple-module
2187 <div class="note">This section should only be used if you need to have one
2188 configuration file that works whether or not a specific module
2189 is available. In normal operation, directives need not be
2190 placed in <code class="directive"><IfModule></code>
2194 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2195 <div class="directive-section"><h2><a name="Include" id="Include">Include</a> <a name="include" id="include">Directive</a></h2>
2196 <table class="directive">
2197 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2198 the server configuration files</td></tr>
2199 <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>
2200 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2201 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2202 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2203 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directory
2204 wildcard matching available in 2.3.6 and later</td></tr>
2206 <p>This directive allows inclusion of other configuration files
2207 from within the server configuration files.</p>
2209 <p>Shell-style (<code>fnmatch()</code>) wildcard characters can be used
2210 in the filename or directory parts of the path to include several files
2211 at once, in alphabetical order. In addition, if
2212 <code class="directive">Include</code> points to a directory, rather than a file,
2213 Apache httpd will read all files in that directory and any subdirectory.
2214 However, including entire directories is not recommended, because it is
2215 easy to accidentally leave temporary files in a directory that can cause
2216 <code class="program"><a href="../programs/httpd.html">httpd</a></code> to fail. Instead, we encourage you to use the
2217 wildcard syntax shown below, to include files that match a particular
2218 pattern, such as *.conf, for example.</p>
2220 <p>The <code class="directive"><a href="#include">Include</a></code> directive will
2221 <strong>fail with an error</strong> if a wildcard expression does not
2222 match any file. The <code class="directive"><a href="#includeoptional">IncludeOptional</a></code>
2223 directive can be used if non-matching wildcards should be ignored.</p>
2225 <p>The file path specified may be an absolute path, or may be relative
2226 to the <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory.</p>
2230 <pre class="prettyprint lang-config">Include /usr/local/apache2/conf/ssl.conf
2231 Include /usr/local/apache2/conf/vhosts/*.conf</pre>
2234 <p>Or, providing paths relative to your <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory:</p>
2236 <pre class="prettyprint lang-config">Include conf/ssl.conf
2237 Include conf/vhosts/*.conf</pre>
2240 <p>Wildcards may be included in the directory or file portion of the
2241 path. This example will fail if there is no subdirectory in conf/vhosts
2242 that contains at least one *.conf file:</p>
2244 <pre class="prettyprint lang-config">Include conf/vhosts/*/*.conf</pre>
2247 <p>Alternatively, the following command will just be ignored in case of
2248 missing files or directories:</p>
2250 <pre class="prettyprint lang-config">IncludeOptional conf/vhosts/*/*.conf</pre>
2256 <li><code class="directive"><a href="#includeoptional">IncludeOptional</a></code></li>
2257 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
2260 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2261 <div class="directive-section"><h2><a name="IncludeOptional" id="IncludeOptional">IncludeOptional</a> <a name="includeoptional" id="includeoptional">Directive</a></h2>
2262 <table class="directive">
2263 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2264 the server configuration files</td></tr>
2265 <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>
2266 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2267 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2268 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2269 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in 2.3.6 and later</td></tr>
2271 <p>This directive allows inclusion of other configuration files
2272 from within the server configuration files. It works identically to the
2273 <code class="directive"><a href="#include">Include</a></code> directive, with the
2274 exception that if wildcards do not match any file or directory, the
2275 <code class="directive"><a href="#includeoptional">IncludeOptional</a></code> directive will be
2276 silently ignored instead of causing an error.</p>
2280 <li><code class="directive"><a href="#include">Include</a></code></li>
2281 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
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="KeepAlive" id="KeepAlive">KeepAlive</a> <a name="keepalive" id="keepalive">Directive</a></h2>
2286 <table class="directive">
2287 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables HTTP persistent connections</td></tr>
2288 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAlive On|Off</code></td></tr>
2289 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAlive On</code></td></tr>
2290 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</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>
2294 <p>The Keep-Alive extension to HTTP/1.0 and the persistent
2295 connection feature of HTTP/1.1 provide long-lived HTTP sessions
2296 which allow multiple requests to be sent over the same TCP
2297 connection. In some cases this has been shown to result in an
2298 almost 50% speedup in latency times for HTML documents with
2299 many images. To enable Keep-Alive connections, set
2300 <code>KeepAlive On</code>.</p>
2302 <p>For HTTP/1.0 clients, Keep-Alive connections will only be
2303 used if they are specifically requested by a client. In
2304 addition, a Keep-Alive connection with an HTTP/1.0 client can
2305 only be used when the length of the content is known in
2306 advance. This implies that dynamic content such as CGI output,
2307 SSI pages, and server-generated directory listings will
2308 generally not use Keep-Alive connections to HTTP/1.0 clients.
2309 For HTTP/1.1 clients, persistent connections are the default
2310 unless otherwise specified. If the client requests it, chunked
2311 encoding will be used in order to send content of unknown
2312 length over persistent connections.</p>
2314 <p>When a client uses a Keep-Alive connection, it will be counted
2315 as a single "request" for the <code class="directive"><a href="../mod/mpm_common.html#maxconnectionsperchild">MaxConnectionsPerChild</a></code> directive, regardless
2316 of how many requests are sent using the connection.</p>
2320 <li><code class="directive"><a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></code></li>
2323 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2324 <div class="directive-section"><h2><a name="KeepAliveTimeout" id="KeepAliveTimeout">KeepAliveTimeout</a> <a name="keepalivetimeout" id="keepalivetimeout">Directive</a></h2>
2325 <table class="directive">
2326 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for subsequent
2327 requests on a persistent connection</td></tr>
2328 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAliveTimeout <var>num</var>[ms]</code></td></tr>
2329 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAliveTimeout 5</code></td></tr>
2330 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2331 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2332 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2334 <p>The number of seconds Apache httpd will wait for a subsequent
2335 request before closing the connection. By adding a postfix of ms the
2336 timeout can be also set in milliseconds. Once a request has been
2337 received, the timeout value specified by the
2338 <code class="directive"><a href="#timeout">Timeout</a></code> directive applies.</p>
2340 <p>Setting <code class="directive">KeepAliveTimeout</code> to a high value
2341 may cause performance problems in heavily loaded servers. The
2342 higher the timeout, the more server processes will be kept
2343 occupied waiting on connections with idle clients.</p>
2345 <p>If <code class="directive">KeepAliveTimeout</code> is <strong>not</strong>
2346 set for a name-based virtual host, the value of the first defined
2347 virtual host best matching the local IP and port will be used.</p>
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="Limit" id="Limit"><Limit></a> <a name="limit" id="limit">Directive</a></h2>
2352 <table class="directive">
2353 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict enclosed access controls to only certain HTTP
2355 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Limit <var>method</var> [<var>method</var>] ... > ...
2356 </Limit></code></td></tr>
2357 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2358 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2359 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2360 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2362 <p>Access controls are normally effective for
2363 <strong>all</strong> access methods, and this is the usual
2364 desired behavior. <strong>In the general case, access control
2365 directives should not be placed within a
2366 <code class="directive"><Limit></code> section.</strong></p>
2368 <p>The purpose of the <code class="directive"><Limit></code>
2369 directive is to restrict the effect of the access controls to the
2370 nominated HTTP methods. For all other methods, the access
2371 restrictions that are enclosed in the <code class="directive"><Limit></code> bracket <strong>will have no
2372 effect</strong>. The following example applies the access control
2373 only to the methods <code>POST</code>, <code>PUT</code>, and
2374 <code>DELETE</code>, leaving all other methods unprotected:</p>
2376 <pre class="prettyprint lang-config"><Limit POST PUT DELETE>
2378 </Limit></pre>
2381 <p>The method names listed can be one or more of: <code>GET</code>,
2382 <code>POST</code>, <code>PUT</code>, <code>DELETE</code>,
2383 <code>CONNECT</code>, <code>OPTIONS</code>,
2384 <code>PATCH</code>, <code>PROPFIND</code>, <code>PROPPATCH</code>,
2385 <code>MKCOL</code>, <code>COPY</code>, <code>MOVE</code>,
2386 <code>LOCK</code>, and <code>UNLOCK</code>. <strong>The method name is
2387 case-sensitive.</strong> If <code>GET</code> is used, it will also
2388 restrict <code>HEAD</code> requests. The <code>TRACE</code> method
2389 cannot be limited (see <code class="directive"><a href="#traceenable">TraceEnable</a></code>).</p>
2391 <div class="warning">A <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section should always be
2392 used in preference to a <code class="directive"><Limit></code>
2393 section when restricting access, since a <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section provides protection
2394 against arbitrary methods.</div>
2396 <p>The <code class="directive"><Limit></code> and
2397 <code class="directive"><a href="#limitexcept"><LimitExcept></a></code>
2398 directives may be nested. In this case, each successive level of
2399 <code class="directive"><Limit></code> or <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> directives must
2400 further restrict the set of methods to which access controls apply.</p>
2402 <div class="warning">When using
2403 <code class="directive"><Limit></code> or
2404 <code class="directive"><LimitExcept></code> directives with
2405 the <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directive,
2406 note that the first <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code>
2407 to succeed authorizes the request, regardless of the presence of other
2408 <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directives.</div>
2410 <p>For example, given the following configuration, all users will
2411 be authorized for <code>POST</code> requests, and the
2412 <code>Require group editors</code> directive will be ignored
2415 <pre class="prettyprint lang-config"><LimitExcept GET>
2417 </LimitExcept>
2419 Require group editors
2420 </Limit></pre>
2424 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2425 <div class="directive-section"><h2><a name="LimitExcept" id="LimitExcept"><LimitExcept></a> <a name="limitexcept" id="limitexcept">Directive</a></h2>
2426 <table class="directive">
2427 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict access controls to all HTTP methods
2428 except the named ones</td></tr>
2429 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LimitExcept <var>method</var> [<var>method</var>] ... > ...
2430 </LimitExcept></code></td></tr>
2431 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2432 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2433 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2434 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2436 <p><code class="directive"><LimitExcept></code> and
2437 <code></LimitExcept></code> are used to enclose
2438 a group of access control directives which will then apply to any
2439 HTTP access method <strong>not</strong> listed in the arguments;
2440 i.e., it is the opposite of a <code class="directive"><a href="#limit"><Limit></a></code> section and can be used to control
2441 both standard and nonstandard/unrecognized methods. See the
2442 documentation for <code class="directive"><a href="#limit"><Limit></a></code> for more details.</p>
2446 <pre class="prettyprint lang-config"><LimitExcept POST GET>
2448 </LimitExcept></pre>
2453 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2454 <div class="directive-section"><h2><a name="LimitInternalRecursion" id="LimitInternalRecursion">LimitInternalRecursion</a> <a name="limitinternalrecursion" id="limitinternalrecursion">Directive</a></h2>
2455 <table class="directive">
2456 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine maximum number of internal redirects and nested
2457 subrequests</td></tr>
2458 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitInternalRecursion <var>number</var> [<var>number</var>]</code></td></tr>
2459 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitInternalRecursion 10</code></td></tr>
2460 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2461 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2462 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2464 <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
2465 redirects the original request to a CGI script. A subrequest is Apache httpd's
2466 mechanism to find out what would happen for some URI if it were requested.
2467 For example, <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> uses subrequests to look for the
2468 files listed in the <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
2471 <p><code class="directive">LimitInternalRecursion</code> prevents the server
2472 from crashing when entering an infinite loop of internal redirects or
2473 subrequests. Such loops are usually caused by misconfigurations.</p>
2475 <p>The directive stores two different limits, which are evaluated on
2476 per-request basis. The first <var>number</var> is the maximum number of
2477 internal redirects that may follow each other. The second <var>number</var>
2478 determines how deeply subrequests may be nested. If you specify only one
2479 <var>number</var>, it will be assigned to both limits.</p>
2481 <pre class="prettyprint lang-config">LimitInternalRecursion 5</pre>
2485 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2486 <div class="directive-section"><h2><a name="LimitRequestBody" id="LimitRequestBody">LimitRequestBody</a> <a name="limitrequestbody" id="limitrequestbody">Directive</a></h2>
2487 <table class="directive">
2488 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restricts the total size of the HTTP request body sent
2489 from the client</td></tr>
2490 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestBody <var>bytes</var></code></td></tr>
2491 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestBody 0</code></td></tr>
2492 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2493 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2494 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2495 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2497 <p>This directive specifies the number of <var>bytes</var> from 0
2498 (meaning unlimited) to 2147483647 (2GB) that are allowed in a
2499 request body. See the note below for the limited applicability
2500 to proxy requests.</p>
2502 <p>The <code class="directive">LimitRequestBody</code> directive allows
2503 the user to set a limit on the allowed size of an HTTP request
2504 message body within the context in which the directive is given
2505 (server, per-directory, per-file or per-location). If the client
2506 request exceeds that limit, the server will return an error
2507 response instead of servicing the request. The size of a normal
2508 request message body will vary greatly depending on the nature of
2509 the resource and the methods allowed on that resource. CGI scripts
2510 typically use the message body for retrieving form information.
2511 Implementations of the <code>PUT</code> method will require
2512 a value at least as large as any representation that the server
2513 wishes to accept for that resource.</p>
2515 <p>This directive gives the server administrator greater
2516 control over abnormal client request behavior, which may be
2517 useful for avoiding some forms of denial-of-service
2520 <p>If, for example, you are permitting file upload to a particular
2521 location and wish to limit the size of the uploaded file to 100K,
2522 you might use the following directive:</p>
2524 <pre class="prettyprint lang-config">LimitRequestBody 102400</pre>
2527 <div class="note"><p>For a full description of how this directive is interpreted by
2528 proxy requests, see the <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> documentation.</p>
2533 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2534 <div class="directive-section"><h2><a name="LimitRequestFields" id="LimitRequestFields">LimitRequestFields</a> <a name="limitrequestfields" id="limitrequestfields">Directive</a></h2>
2535 <table class="directive">
2536 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of HTTP request header fields that
2537 will be accepted from the client</td></tr>
2538 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFields <var>number</var></code></td></tr>
2539 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFields 100</code></td></tr>
2540 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2541 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2542 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2544 <p><var>Number</var> is an integer from 0 (meaning unlimited) to
2545 32767. The default value is defined by the compile-time
2546 constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
2549 <p>The <code class="directive">LimitRequestFields</code> directive allows
2550 the server administrator to modify the limit on the number of
2551 request header fields allowed in an HTTP request. A server needs
2552 this value to be larger than the number of fields that a normal
2553 client request might include. The number of request header fields
2554 used by a client rarely exceeds 20, but this may vary among
2555 different client implementations, often depending upon the extent
2556 to which a user has configured their browser to support detailed
2557 content negotiation. Optional HTTP extensions are often expressed
2558 using request header fields.</p>
2560 <p>This directive gives the server administrator greater
2561 control over abnormal client request behavior, which may be
2562 useful for avoiding some forms of denial-of-service attacks.
2563 The value should be increased if normal clients see an error
2564 response from the server that indicates too many fields were
2565 sent in the request.</p>
2569 <pre class="prettyprint lang-config">LimitRequestFields 50</pre>
2572 <div class="warning"><h3>Warning</h3>
2573 <p> When name-based virtual hosting is used, the value for this
2574 directive is taken from the default (first-listed) virtual host for the
2575 local IP and port combination.</p>
2580 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2581 <div class="directive-section"><h2><a name="LimitRequestFieldSize" id="LimitRequestFieldSize">LimitRequestFieldSize</a> <a name="limitrequestfieldsize" id="limitrequestfieldsize">Directive</a></h2>
2582 <table class="directive">
2583 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of the HTTP request header allowed from the
2585 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFieldSize <var>bytes</var></code></td></tr>
2586 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFieldSize 8190</code></td></tr>
2587 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2588 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2589 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2591 <p>This directive specifies the number of <var>bytes</var>
2592 that will be allowed in an HTTP request header.</p>
2594 <p>The <code class="directive">LimitRequestFieldSize</code> directive
2595 allows the server administrator to set the limit
2596 on the allowed size of an HTTP request header field. A server
2597 needs this value to be large enough to hold any one header field
2598 from a normal client request. The size of a normal request header
2599 field will vary greatly among different client implementations,
2600 often depending upon the extent to which a user has configured
2601 their browser to support detailed content negotiation. SPNEGO
2602 authentication headers can be up to 12392 bytes.</p>
2604 <p>This directive gives the server administrator greater
2605 control over abnormal client request behavior, which may be
2606 useful for avoiding some forms of denial-of-service attacks.</p>
2610 <pre class="prettyprint lang-config">LimitRequestFieldSize 4094</pre>
2613 <div class="note">Under normal conditions, the value should not be changed from
2616 <div class="warning"><h3>Warning</h3>
2617 <p> When name-based virtual hosting is used, the value for this
2618 directive is taken from the default (first-listed) virtual host best
2619 matching the current IP address and port combination.</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="LimitRequestLine" id="LimitRequestLine">LimitRequestLine</a> <a name="limitrequestline" id="limitrequestline">Directive</a></h2>
2625 <table class="directive">
2626 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limit the size of the HTTP request line that will be accepted
2627 from the client</td></tr>
2628 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestLine <var>bytes</var></code></td></tr>
2629 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestLine 8190</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>This directive sets the number of <var>bytes</var> that will be
2635 allowed on the HTTP request-line.</p>
2637 <p>The <code class="directive">LimitRequestLine</code> directive allows
2638 the server administrator to set the limit on the allowed size
2639 of a client's HTTP request-line. Since the request-line consists of the
2640 HTTP method, URI, and protocol version, the
2641 <code class="directive">LimitRequestLine</code> directive places a
2642 restriction on the length of a request-URI allowed for a request
2643 on the server. A server needs this value to be large enough to
2644 hold any of its resource names, including any information that
2645 might be passed in the query part of a <code>GET</code> request.</p>
2647 <p>This directive gives the server administrator greater
2648 control over abnormal client request behavior, which may be
2649 useful for avoiding some forms of denial-of-service attacks.</p>
2653 <pre class="prettyprint lang-config">LimitRequestLine 4094</pre>
2656 <div class="note">Under normal conditions, the value should not be changed from
2659 <div class="warning"><h3>Warning</h3>
2660 <p> When name-based virtual hosting is used, the value for this
2661 directive is taken from the default (first-listed) virtual host best
2662 matching the current IP address and port combination.</p>
2667 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2668 <div class="directive-section"><h2><a name="LimitXMLRequestBody" id="LimitXMLRequestBody">LimitXMLRequestBody</a> <a name="limitxmlrequestbody" id="limitxmlrequestbody">Directive</a></h2>
2669 <table class="directive">
2670 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of an XML-based request body</td></tr>
2671 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitXMLRequestBody <var>bytes</var></code></td></tr>
2672 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitXMLRequestBody 1000000</code></td></tr>
2673 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2674 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2675 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2676 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2678 <p>Limit (in bytes) on maximum size of an XML-based request
2679 body. A value of <code>0</code> will disable any checking.</p>
2683 <pre class="prettyprint lang-config">LimitXMLRequestBody 0</pre>
2688 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2689 <div class="directive-section"><h2><a name="Location" id="Location"><Location></a> <a name="location" id="location">Directive</a></h2>
2690 <table class="directive">
2691 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to matching
2693 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Location
2694 <var>URL-path</var>|<var>URL</var>> ... </Location></code></td></tr>
2695 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2696 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2697 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2699 <p>The <code class="directive"><Location></code> directive
2700 limits the scope of the enclosed directives by URL. It is similar to the
2701 <code class="directive"><a href="#directory"><Directory></a></code>
2702 directive, and starts a subsection which is terminated with a
2703 <code></Location></code> directive. <code class="directive"><Location></code> sections are processed in the
2704 order they appear in the configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
2705 <code>.htaccess</code> files are read, and after the <code class="directive"><a href="#files"><Files></a></code> sections.</p>
2707 <p><code class="directive"><Location></code> sections operate
2708 completely outside the filesystem. This has several consequences.
2709 Most importantly, <code class="directive"><Location></code>
2710 directives should not be used to control access to filesystem
2711 locations. Since several different URLs may map to the same
2712 filesystem location, such access controls may by circumvented.</p>
2714 <p>The enclosed directives will be applied to the request if the path component
2715 of the URL meets <em>any</em> of the following criteria:
2718 <li>The specified location matches exactly the path component of the URL.
2720 <li>The specified location, which ends in a forward slash, is a prefix
2721 of the path component of the URL (treated as a context root).
2723 <li>The specified location, with the addition of a trailing slash, is a
2724 prefix of the path component of the URL (also treated as a context root).
2728 In the example below, where no trailing slash is used, requests to
2729 /private1, /private1/ and /private1/file.txt will have the enclosed
2730 directives applied, but /private1other would not.
2732 <pre class="prettyprint lang-config"><Location "/private1">
2734 </Location></pre>
2737 In the example below, where a trailing slash is used, requests to
2738 /private2/ and /private2/file.txt will have the enclosed
2739 directives applied, but /private2 and /private2other would not.
2741 <pre class="prettyprint lang-config"><Location "/private2<em>/</em>">
2743 </Location></pre>
2746 <div class="note"><h3>When to use <code class="directive"><Location></code></h3>
2748 <p>Use <code class="directive"><Location></code> to apply
2749 directives to content that lives outside the filesystem. For
2750 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
2751 <code><Location "/"></code>, which is an easy way to
2752 apply a configuration to the entire server.</p>
2755 <p>For all origin (non-proxy) requests, the URL to be matched is a
2756 URL-path of the form <code>/path/</code>. <em>No scheme, hostname,
2757 port, or query string may be included.</em> For proxy requests, the
2758 URL to be matched is of the form
2759 <code>scheme://servername/path</code>, and you must include the
2762 <p>The URL may use wildcards. In a wild-card string, <code>?</code> matches
2763 any single character, and <code>*</code> matches any sequences of
2764 characters. Neither wildcard character matches a / in the URL-path.</p>
2766 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
2767 can also be used, with the addition of the <code>~</code>
2768 character. For example:</p>
2770 <pre class="prettyprint lang-config"><Location ~ "/(extra|special)/data">
2772 </Location></pre>
2775 <p>would match URLs that contained the substring <code>/extra/data</code>
2776 or <code>/special/data</code>. The directive <code class="directive"><a href="#locationmatch"><LocationMatch></a></code> behaves
2777 identical to the regex version of <code class="directive"><Location></code>, and is preferred, for the
2778 simple reason that <code>~</code> is hard to distinguish from
2779 <code>-</code> in many fonts.</p>
2781 <p>The <code class="directive"><Location></code>
2782 functionality is especially useful when combined with the
2783 <code class="directive"><a href="#sethandler">SetHandler</a></code>
2784 directive. For example, to enable status requests but allow them
2785 only from browsers at <code>example.com</code>, you might use:</p>
2787 <pre class="prettyprint lang-config"><Location "/status">
2788 SetHandler server-status
2789 Require host example.com
2790 </Location></pre>
2793 <div class="note"><h3>Note about / (slash)</h3>
2794 <p>The slash character has special meaning depending on where in a
2795 URL it appears. People may be used to its behavior in the filesystem
2796 where multiple adjacent slashes are frequently collapsed to a single
2797 slash (<em>i.e.</em>, <code>/home///foo</code> is the same as
2798 <code>/home/foo</code>). In URL-space this is not necessarily true.
2799 The <code class="directive"><a href="#locationmatch"><LocationMatch></a></code>
2800 directive and the regex version of <code class="directive"><Location></code> require you to explicitly specify multiple
2801 slashes if that is your intention.</p>
2803 <p>For example, <code><LocationMatch "^/abc"></code> would match
2804 the request URL <code>/abc</code> but not the request URL <code>
2805 //abc</code>. The (non-regex) <code class="directive"><Location></code> directive behaves similarly when used for
2806 proxy requests. But when (non-regex) <code class="directive"><Location></code> is used for non-proxy requests it will
2807 implicitly match multiple slashes with a single slash. For example,
2808 if you specify <code><Location "/abc/def"></code> and the
2809 request is to <code>/abc//def</code> then it will match.</p>
2814 <li><a href="../sections.html">How <Directory>, <Location>
2815 and <Files> sections work</a> for an explanation of how these
2816 different sections are combined when a request is received.</li>
2817 <li><code class="directive"><a href="#locationmatch">LocationMatch</a></code></li>
2820 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2821 <div class="directive-section"><h2><a name="LocationMatch" id="LocationMatch"><LocationMatch></a> <a name="locationmatch" id="locationmatch">Directive</a></h2>
2822 <table class="directive">
2823 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to regular-expression
2824 matching URLs</td></tr>
2825 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LocationMatch
2826 <var>regex</var>> ... </LocationMatch></code></td></tr>
2827 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2828 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2829 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2831 <p>The <code class="directive"><LocationMatch></code> directive
2832 limits the scope of the enclosed directives by URL, in an identical manner
2833 to <code class="directive"><a href="#location"><Location></a></code>. However,
2834 it takes a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>
2835 as an argument instead of a simple string. For example:</p>
2837 <pre class="prettyprint lang-config"><LocationMatch "/(extra|special)/data">
2839 </LocationMatch></pre>
2842 <p>would match URLs that contained the substring <code>/extra/data</code>
2843 or <code>/special/data</code>.</p>
2845 <div class="note"><p>If the intent is that a URL <strong>starts with</strong>
2846 <code>/extra/data</code>, rather than merely
2847 <strong>contains</strong> <code>/extra/data</code>, prefix the
2848 regular expression with a <code>^</code> to require this.</p>
2850 <pre class="prettyprint lang-config"><LocationMatch "^/(extra|special)/data"></pre>
2854 <p>From 2.4.8 onwards, named groups and backreferences are captured and
2855 written to the environment with the corresponding name prefixed with
2856 "MATCH_" and in upper case. This allows elements of URLs to be referenced
2857 from within <a href="../expr.html">expressions</a> and modules like
2858 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
2859 (unnamed) backreferences are ignored. Use named groups instead.</p>
2861 <pre class="prettyprint lang-config"><LocationMatch "^/combined/(?<sitename>[^/]+)">
2862 require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
2863 </LocationMatch></pre>
2868 <li><a href="../sections.html">How <Directory>, <Location>
2869 and <Files> sections work</a> for an explanation of how these
2870 different sections are combined when a request is received</li>
2873 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2874 <div class="directive-section"><h2><a name="LogLevel" id="LogLevel">LogLevel</a> <a name="loglevel" id="loglevel">Directive</a></h2>
2875 <table class="directive">
2876 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls the verbosity of the ErrorLog</td></tr>
2877 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel [<var>module</var>:]<var>level</var>
2878 [<var>module</var>:<var>level</var>] ...
2880 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LogLevel warn</code></td></tr>
2881 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2882 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2883 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2884 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Per-module and per-directory configuration is available in
2885 Apache HTTP Server 2.3.6 and later</td></tr>
2887 <p><code class="directive">LogLevel</code> adjusts the verbosity of the
2888 messages recorded in the error logs (see <code class="directive"><a href="#errorlog">ErrorLog</a></code> directive). The following
2889 <var>level</var>s are available, in order of decreasing
2892 <table class="bordered">
2895 <th><strong>Level</strong> </th>
2897 <th><strong>Description</strong> </th>
2899 <th><strong>Example</strong> </th>
2903 <td><code>emerg</code> </td>
2905 <td>Emergencies - system is unusable.</td>
2907 <td>"Child cannot open lock file. Exiting"</td>
2911 <td><code>alert</code> </td>
2913 <td>Action must be taken immediately.</td>
2915 <td>"getpwuid: couldn't determine user name from uid"</td>
2919 <td><code>crit</code> </td>
2921 <td>Critical Conditions.</td>
2923 <td>"socket: Failed to get a socket, exiting child"</td>
2927 <td><code>error</code> </td>
2929 <td>Error conditions.</td>
2931 <td>"Premature end of script headers"</td>
2935 <td><code>warn</code> </td>
2937 <td>Warning conditions.</td>
2939 <td>"child process 1234 did not exit, sending another
2944 <td><code>notice</code> </td>
2946 <td>Normal but significant condition.</td>
2948 <td>"httpd: caught SIGBUS, attempting to dump core in
2953 <td><code>info</code> </td>
2955 <td>Informational.</td>
2957 <td>"Server seems busy, (you may need to increase
2958 StartServers, or Min/MaxSpareServers)..."</td>
2962 <td><code>debug</code> </td>
2964 <td>Debug-level messages</td>
2966 <td>"Opening config file ..."</td>
2969 <td><code>trace1</code> </td>
2971 <td>Trace messages</td>
2973 <td>"proxy: FTP: control connection complete"</td>
2976 <td><code>trace2</code> </td>
2978 <td>Trace messages</td>
2980 <td>"proxy: CONNECT: sending the CONNECT request to the remote proxy"</td>
2983 <td><code>trace3</code> </td>
2985 <td>Trace messages</td>
2987 <td>"openssl: Handshake: start"</td>
2990 <td><code>trace4</code> </td>
2992 <td>Trace messages</td>
2994 <td>"read from buffered SSL brigade, mode 0, 17 bytes"</td>
2997 <td><code>trace5</code> </td>
2999 <td>Trace messages</td>
3001 <td>"map lookup FAILED: map=rewritemap key=keyname"</td>
3004 <td><code>trace6</code> </td>
3006 <td>Trace messages</td>
3008 <td>"cache lookup FAILED, forcing new map lookup"</td>
3011 <td><code>trace7</code> </td>
3013 <td>Trace messages, dumping large amounts of data</td>
3015 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3018 <td><code>trace8</code> </td>
3020 <td>Trace messages, dumping large amounts of data</td>
3022 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3026 <p>When a particular level is specified, messages from all
3027 other levels of higher significance will be reported as well.
3028 <em>E.g.</em>, when <code>LogLevel info</code> is specified,
3029 then messages with log levels of <code>notice</code> and
3030 <code>warn</code> will also be posted.</p>
3032 <p>Using a level of at least <code>crit</code> is
3037 <pre class="prettyprint lang-config">LogLevel notice</pre>
3040 <div class="note"><h3>Note</h3>
3041 <p>When logging to a regular file, messages of the level
3042 <code>notice</code> cannot be suppressed and thus are always
3043 logged. However, this doesn't apply when logging is done
3044 using <code>syslog</code>.</p>
3047 <p>Specifying a level without a module name will reset the level
3048 for all modules to that level. Specifying a level with a module
3049 name will set the level for that module only. It is possible to
3050 use the module source file name, the module identifier, or the
3051 module identifier with the trailing <code>_module</code> omitted
3052 as module specification. This means the following three specifications
3055 <pre class="prettyprint lang-config">LogLevel info ssl:warn
3056 LogLevel info mod_ssl.c:warn
3057 LogLevel info ssl_module:warn</pre>
3060 <p>It is also possible to change the level per directory:</p>
3062 <pre class="prettyprint lang-config">LogLevel info
3063 <Directory "/usr/local/apache/htdocs/app">
3065 </Directory></pre>
3069 Per directory loglevel configuration only affects messages that are
3070 logged after the request has been parsed and that are associated with
3071 the request. Log messages which are associated with the server or
3072 the connection are not affected. The latter can be influenced by the
3073 <code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code> directive,
3079 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
3080 <li><code class="directive"><a href="#errorlogformat">ErrorLogFormat</a></code></li>
3081 <li><code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code></li>
3082 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
3085 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3086 <div class="directive-section"><h2><a name="LogLevelOverride" id="LogLevelOverride">LogLevelOverride</a> <a name="logleveloverride" id="logleveloverride">Directive</a></h2>
3087 <table class="directive">
3088 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Override the verbosity of the ErrorLog for certain clients</td></tr>
3089 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel <var>ipaddress</var>[/<var>prefixlen</var>]
3090 [<var>module</var>:]<var>level</var> [<var>module</var>:<var>level</var>] ...
3092 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>unset</code></td></tr>
3093 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3094 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3095 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3096 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.5.0 and later</td></tr>
3098 <p><code class="directive">LogLevelOverride</code> adjusts the
3099 <code class="directive"><a href="#loglevel">LogLevel</a></code> for requests coming from
3100 certain client IP addresses.
3101 This allows to enable verbose logging only for certain test clients.
3102 The IP address is checked at a very early state in the connection
3103 processing. Therefore, <code class="directive">LogLevelOverride</code> allows to
3104 change the log level for things like the SSL handshake which happen before
3105 a <code class="directive"><a href="#loglevel">LogLevel</a></code> directive in an
3106 <code class="directive"><a href="#if"><If></a></code> container would
3109 <p><code class="directive">LogLevelOverride</code> accepts either a single
3110 IP-address or a CIDR IP-address/len subnet specification.
3111 For the syntax of the loglevel specification, see the
3112 <code class="directive"><a href="#loglevel">LogLevel</a></code> directive.</p>
3114 <p>For requests that match a <code class="directive">LogLevelOverride</code>
3115 directive, per-directory specifications of
3116 <code class="directive"><a href="#loglevel">LogLevel</a></code> are ignored.</p>
3120 <pre class="prettyprint lang-config"> LogLevelOverride 192.0.2.0/24 ssl:trace6
3121 LogLevelOverride 192.0.2.7 ssl:trace8</pre>
3125 <code class="directive">LogLevelOverride</code> only affects
3126 log messages that are associated with the request or the connection.
3127 Log messages which are associated with the server are not affected.
3133 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
3136 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3137 <div class="directive-section"><h2><a name="MaxKeepAliveRequests" id="MaxKeepAliveRequests">MaxKeepAliveRequests</a> <a name="maxkeepaliverequests" id="maxkeepaliverequests">Directive</a></h2>
3138 <table class="directive">
3139 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of requests allowed on a persistent
3140 connection</td></tr>
3141 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxKeepAliveRequests <var>number</var></code></td></tr>
3142 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxKeepAliveRequests 100</code></td></tr>
3143 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3144 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3145 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3147 <p>The <code class="directive">MaxKeepAliveRequests</code> directive
3148 limits the number of requests allowed per connection when
3149 <code class="directive"><a href="#keepalive">KeepAlive</a></code> is on. If it is
3150 set to <code>0</code>, unlimited requests will be allowed. We
3151 recommend that this setting be kept to a high value for maximum
3152 server performance.</p>
3156 <pre class="prettyprint lang-config">MaxKeepAliveRequests 500</pre>
3160 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3161 <div class="directive-section"><h2><a name="MaxRangeOverlaps" id="MaxRangeOverlaps">MaxRangeOverlaps</a> <a name="maxrangeoverlaps" id="maxrangeoverlaps">Directive</a></h2>
3162 <table class="directive">
3163 <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
3165 <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>
3166 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeOverlaps 20</code></td></tr>
3167 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3168 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3169 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3170 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3172 <p>The <code class="directive">MaxRangeOverlaps</code> directive
3173 limits the number of overlapping HTTP ranges the server is willing to
3174 return to the client. If more overlapping ranges than permitted are requested,
3175 the complete resource is returned instead.</p>
3178 <dt><strong>default</strong></dt>
3179 <dd>Limits the number of overlapping ranges to a compile-time default of 20.</dd>
3181 <dt><strong>none</strong></dt>
3182 <dd>No overlapping Range headers are allowed.</dd>
3184 <dt><strong>unlimited</strong></dt>
3185 <dd>The server does not limit the number of overlapping ranges it is
3186 willing to satisfy.</dd>
3188 <dt><var>number-of-ranges</var></dt>
3189 <dd>A positive number representing the maximum number of overlapping ranges the
3190 server is willing to satisfy.</dd>
3194 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3195 <div class="directive-section"><h2><a name="MaxRangeReversals" id="MaxRangeReversals">MaxRangeReversals</a> <a name="maxrangereversals" id="maxrangereversals">Directive</a></h2>
3196 <table class="directive">
3197 <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
3199 <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>
3200 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeReversals 20</code></td></tr>
3201 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3202 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3203 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3204 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3206 <p>The <code class="directive">MaxRangeReversals</code> directive
3207 limits the number of HTTP Range reversals the server is willing to
3208 return to the client. If more ranges reversals than permitted are requested,
3209 the complete resource is returned instead.</p>
3212 <dt><strong>default</strong></dt>
3213 <dd>Limits the number of range reversals to a compile-time default of 20.</dd>
3215 <dt><strong>none</strong></dt>
3216 <dd>No Range reversals headers are allowed.</dd>
3218 <dt><strong>unlimited</strong></dt>
3219 <dd>The server does not limit the number of range reversals it is
3220 willing to satisfy.</dd>
3222 <dt><var>number-of-ranges</var></dt>
3223 <dd>A positive number representing the maximum number of range reversals the
3224 server is willing to satisfy.</dd>
3228 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3229 <div class="directive-section"><h2><a name="MaxRanges" id="MaxRanges">MaxRanges</a> <a name="maxranges" id="maxranges">Directive</a></h2>
3230 <table class="directive">
3231 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of ranges allowed before returning the complete
3233 <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>
3234 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRanges 200</code></td></tr>
3235 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3236 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3237 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3238 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3240 <p>The <code class="directive">MaxRanges</code> directive
3241 limits the number of HTTP ranges the server is willing to
3242 return to the client. If more ranges than permitted are requested,
3243 the complete resource is returned instead.</p>
3246 <dt><strong>default</strong></dt>
3247 <dd>Limits the number of ranges to a compile-time default of 200.</dd>
3249 <dt><strong>none</strong></dt>
3250 <dd>Range headers are ignored.</dd>
3252 <dt><strong>unlimited</strong></dt>
3253 <dd>The server does not limit the number of ranges it is
3254 willing to satisfy.</dd>
3256 <dt><var>number-of-ranges</var></dt>
3257 <dd>A positive number representing the maximum number of ranges the
3258 server is willing to satisfy.</dd>
3262 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3263 <div class="directive-section"><h2><a name="MergeTrailers" id="MergeTrailers">MergeTrailers</a> <a name="mergetrailers" id="mergetrailers">Directive</a></h2>
3264 <table class="directive">
3265 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether trailers are merged into headers</td></tr>
3266 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MergeTrailers [on|off]</code></td></tr>
3267 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MergeTrailers off</code></td></tr>
3268 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3269 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3270 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3271 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.4.11 and later</td></tr>
3273 <p>This directive controls whether HTTP trailers are copied into the
3274 internal representation of HTTP headers. This merging occurs when the
3275 request body has been completely consumed, long after most header
3276 processing would have a chance to examine or modify request headers.</p>
3277 <p>This option is provided for compatibility with releases prior to 2.4.11,
3278 where trailers were always merged.</p>
3281 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3282 <div class="directive-section"><h2><a name="Mutex" id="Mutex">Mutex</a> <a name="mutex" id="mutex">Directive</a></h2>
3283 <table class="directive">
3284 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures mutex mechanism and lock file directory for all
3285 or specified mutexes</td></tr>
3286 <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>
3287 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Mutex default</code></td></tr>
3288 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3289 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3290 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3291 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.4 and later</td></tr>
3293 <p>The <code class="directive">Mutex</code> directive sets the mechanism,
3294 and optionally the lock file location, that httpd and modules use
3295 to serialize access to resources. Specify <code>default</code> as
3296 the second argument to change the settings for all mutexes; specify
3297 a mutex name (see table below) as the second argument to override
3298 defaults only for that mutex.</p>
3300 <p>The <code class="directive">Mutex</code> directive is typically used in
3301 the following exceptional situations:</p>
3304 <li>change the mutex mechanism when the default mechanism selected
3305 by <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> has a functional or performance
3308 <li>change the directory used by file-based mutexes when the
3309 default directory does not support locking</li>
3312 <div class="note"><h3>Supported modules</h3>
3313 <p>This directive only configures mutexes which have been registered
3314 with the core server using the <code>ap_mutex_register()</code> API.
3315 All modules bundled with httpd support the <code class="directive">Mutex</code>
3316 directive, but third-party modules may not. Consult the documentation
3317 of the third-party module, which must indicate the mutex name(s) which
3318 can be configured if this directive is supported.</p>
3321 <p>The following mutex <em>mechanisms</em> are available:</p>
3323 <li><code>default | yes</code>
3324 <p>This selects the default locking implementation, as determined by
3325 <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a>. The default locking implementation can
3326 be displayed by running <code class="program"><a href="../programs/httpd.html">httpd</a></code> with the
3327 <code>-V</code> option.</p></li>
3329 <li><code>none | no</code>
3330 <p>This effectively disables the mutex, and is only allowed for a
3331 mutex if the module indicates that it is a valid choice. Consult the
3332 module documentation for more information.</p></li>
3334 <li><code>posixsem</code>
3335 <p>This is a mutex variant based on a Posix semaphore.</p>
3337 <div class="warning"><h3>Warning</h3>
3338 <p>The semaphore ownership is not recovered if a thread in the process
3339 holding the mutex segfaults, resulting in a hang of the web server.</p>
3343 <li><code>sysvsem</code>
3344 <p>This is a mutex variant based on a SystemV IPC semaphore.</p>
3346 <div class="warning"><h3>Warning</h3>
3347 <p>It is possible to "leak" SysV semaphores if processes crash
3348 before the semaphore is removed.</p>
3351 <div class="warning"><h3>Security</h3>
3352 <p>The semaphore API allows for a denial of service attack by any
3353 CGIs running under the same uid as the webserver (<em>i.e.</em>,
3354 all CGIs, unless you use something like <code class="program"><a href="../programs/suexec.html">suexec</a></code>
3355 or <code>cgiwrapper</code>).</p>
3359 <li><code>sem</code>
3360 <p>This selects the "best" available semaphore implementation, choosing
3361 between Posix and SystemV IPC semaphores, in that order.</p></li>
3363 <li><code>pthread</code>
3364 <p>This is a mutex variant based on cross-process Posix thread
3367 <div class="warning"><h3>Warning</h3>
3368 <p>On most systems, if a child process terminates abnormally while
3369 holding a mutex that uses this implementation, the server will deadlock
3370 and stop responding to requests. When this occurs, the server will
3371 require a manual restart to recover.</p>
3372 <p>Solaris and Linux are notable exceptions as they provide a mechanism which
3373 usually allows the mutex to be recovered after a child process
3374 terminates abnormally while holding a mutex.</p>
3375 <p>If your system is POSIX compliant or if it implements the
3376 <code>pthread_mutexattr_setrobust_np()</code> function, you may be able
3377 to use the <code>pthread</code> option safely.</p>
3381 <li><code>fcntl:/path/to/mutex</code>
3382 <p>This is a mutex variant where a physical (lock-)file and the
3383 <code>fcntl()</code> function are used as the mutex.</p>
3385 <div class="warning"><h3>Warning</h3>
3386 <p>When multiple mutexes based on this mechanism are used within
3387 multi-threaded, multi-process environments, deadlock errors (EDEADLK)
3388 can be reported for valid mutex operations if <code>fcntl()</code>
3389 is not thread-aware, such as on Solaris.</p>
3393 <li><code>flock:/path/to/mutex</code>
3394 <p>This is similar to the <code>fcntl:/path/to/mutex</code> method
3395 with the exception that the <code>flock()</code> function is used to
3396 provide file locking.</p></li>
3398 <li><code>file:/path/to/mutex</code>
3399 <p>This selects the "best" available file locking implementation,
3400 choosing between <code>fcntl</code> and <code>flock</code>, in that
3404 <p>Most mechanisms are only available on selected platforms, where the
3405 underlying platform and <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> support it. Mechanisms
3406 which aren't available on all platforms are <em>posixsem</em>,
3407 <em>sysvsem</em>, <em>sem</em>, <em>pthread</em>, <em>fcntl</em>,
3408 <em>flock</em>, and <em>file</em>.</p>
3410 <p>With the file-based mechanisms <em>fcntl</em> and <em>flock</em>,
3411 the path, if provided, is a directory where the lock file will be created.
3412 The default directory is httpd's run-time file directory,
3413 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. If a relative
3414 path is provided, it is relative to
3415 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. Always use a local
3416 disk filesystem for <code>/path/to/mutex</code> and never a directory residing
3417 on a NFS- or AFS-filesystem. The basename of the file will be the mutex
3418 type, an optional instance string provided by the module, and unless the
3419 <code>OmitPID</code> keyword is specified, the process id of the httpd
3420 parent process will be appended to make the file name unique, avoiding
3421 conflicts when multiple httpd instances share a lock file directory. For
3422 example, if the mutex name is <code>mpm-accept</code> and the lock file
3423 directory is <code>/var/httpd/locks</code>, the lock file name for the
3424 httpd instance with parent process id 12345 would be
3425 <code>/var/httpd/locks/mpm-accept.12345</code>.</p>
3427 <div class="warning"><h3>Security</h3>
3428 <p>It is best to <em>avoid</em> putting mutex files in a world-writable
3429 directory such as <code>/var/tmp</code> because someone could create
3430 a denial of service attack and prevent the server from starting by
3431 creating a lockfile with the same name as the one the server will try
3435 <p>The following table documents the names of mutexes used by httpd
3436 and bundled modules.</p>
3438 <table class="bordered"><tr class="header">
3441 <th>Protected resource</th>
3444 <td><code>mpm-accept</code></td>
3445 <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>
3446 <td>incoming connections, to avoid the thundering herd problem;
3447 for more information, refer to the
3448 <a href="../misc/perf-tuning.html">performance tuning</a>
3452 <td><code>authdigest-client</code></td>
3453 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3454 <td>client list in shared memory</td>
3457 <td><code>authdigest-opaque</code></td>
3458 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3459 <td>counter in shared memory</td>
3462 <td><code>ldap-cache</code></td>
3463 <td><code class="module"><a href="../mod/mod_ldap.html">mod_ldap</a></code></td>
3464 <td>LDAP result cache</td>
3467 <td><code>rewrite-map</code></td>
3468 <td><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></td>
3469 <td>communication with external mapping programs, to avoid
3470 intermixed I/O from multiple requests</td>
3473 <td><code>ssl-cache</code></td>
3474 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3475 <td>SSL session cache</td>
3478 <td><code>ssl-stapling</code></td>
3479 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3480 <td>OCSP stapling response cache</td>
3483 <td><code>watchdog-callback</code></td>
3484 <td><code class="module"><a href="../mod/mod_watchdog.html">mod_watchdog</a></code></td>
3485 <td>callback function of a particular client module</td>
3489 <p>The <code>OmitPID</code> keyword suppresses the addition of the httpd
3490 parent process id from the lock file name.</p>
3492 <p>In the following example, the mutex mechanism for the MPM accept
3493 mutex will be changed from the compiled-in default to <code>fcntl</code>,
3494 with the associated lock file created in directory
3495 <code>/var/httpd/locks</code>. The mutex mechanism for all other mutexes
3496 will be changed from the compiled-in default to <code>sysvsem</code>.</p>
3498 <pre class="prettyprint lang-config">Mutex sysvsem default
3499 Mutex fcntl:/var/httpd/locks mpm-accept</pre>
3503 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3504 <div class="directive-section"><h2><a name="NameVirtualHost" id="NameVirtualHost">NameVirtualHost</a> <a name="namevirtualhost" id="namevirtualhost">Directive</a></h2>
3505 <table class="directive">
3506 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>DEPRECATED: Designates an IP address for name-virtual
3508 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NameVirtualHost <var>addr</var>[:<var>port</var>]</code></td></tr>
3509 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3510 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3511 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3514 <p>Prior to 2.3.11, <code class="directive">NameVirtualHost</code> was required
3515 to instruct the server that a particular IP address and port combination
3516 was usable as a name-based virtual host. In 2.3.11 and later,
3517 any time an IP address and port combination is used in multiple virtual
3518 hosts, name-based virtual hosting is automatically enabled for that address.</p>
3520 <p>This directive currently has no effect.</p>
3524 <li><a href="../vhosts/">Virtual Hosts
3525 documentation</a></li>
3528 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3529 <div class="directive-section"><h2><a name="Options" id="Options">Options</a> <a name="options" id="options">Directive</a></h2>
3530 <table class="directive">
3531 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures what features are available in a particular
3533 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Options
3534 [+|-]<var>option</var> [[+|-]<var>option</var>] ...</code></td></tr>
3535 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Options FollowSymlinks</code></td></tr>
3536 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3537 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
3538 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3539 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3540 <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>
3542 <p>The <code class="directive">Options</code> directive controls which
3543 server features are available in a particular directory.</p>
3545 <p><var>option</var> can be set to <code>None</code>, in which
3546 case none of the extra features are enabled, or one or more of
3550 <dt><code>All</code></dt>
3552 <dd>All options except for <code>MultiViews</code>.</dd>
3554 <dt><code>ExecCGI</code></dt>
3557 Execution of CGI scripts using <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>
3560 <dt><code>FollowSymLinks</code></dt>
3563 The server will follow symbolic links in this directory. This is
3564 the default setting.
3566 <p>Even though the server follows the symlink it does <em>not</em>
3567 change the pathname used to match against <code class="directive"><a href="#directory"><Directory></a></code> sections.</p>
3569 <p>The <code>FollowSymLinks</code> and
3570 <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
3571 <code>.htaccess</code> files.</p>
3573 <p>Omitting this option should not be considered a security restriction,
3574 since symlink testing is subject to race conditions that make it
3578 <dt><code>Includes</code></dt>
3581 Server-side includes provided by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
3584 <dt><code>IncludesNOEXEC</code></dt>
3588 Server-side includes are permitted, but the <code>#exec
3589 cmd</code> and <code>#exec cgi</code> are disabled. It is still
3590 possible to <code>#include virtual</code> CGI scripts from
3591 <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>ed
3594 <dt><code>Indexes</code></dt>
3597 If a URL which maps to a directory is requested and there
3598 is no <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
3599 (<em>e.g.</em>, <code>index.html</code>) in that directory, then
3600 <code class="module"><a href="../mod/mod_autoindex.html">mod_autoindex</a></code> will return a formatted listing
3601 of the directory.</dd>
3603 <dt><code>MultiViews</code></dt>
3606 <a href="../content-negotiation.html">Content negotiated</a>
3607 "MultiViews" are allowed using
3608 <code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code>.
3609 <div class="note"><h3>Note</h3> <p>This option gets ignored if set
3610 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>
3611 needs real resources to compare against and evaluate from.</p></div>
3614 <dt><code>SymLinksIfOwnerMatch</code></dt>
3616 <dd>The server will only follow symbolic links for which the
3617 target file or directory is owned by the same user id as the
3620 <div class="note"><h3>Note</h3>
3621 <p>The <code>FollowSymLinks</code> and
3622 <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
3623 <code>.htaccess</code> files.</p>
3625 <p>This option should not be considered a security restriction,
3626 since symlink testing is subject to race conditions that make it
3631 <p>Normally, if multiple <code class="directive">Options</code> could
3632 apply to a directory, then the most specific one is used and
3633 others are ignored; the options are not merged. (See <a href="../sections.html#mergin">how sections are merged</a>.)
3634 However if <em>all</em> the options on the
3635 <code class="directive">Options</code> directive are preceded by a
3636 <code>+</code> or <code>-</code> symbol, the options are
3637 merged. Any options preceded by a <code>+</code> are added to the
3638 options currently in force, and any options preceded by a
3639 <code>-</code> are removed from the options currently in
3642 <div class="note"><h3>Note</h3>
3643 <p>Mixing <code class="directive">Options</code> with a <code>+</code> or
3644 <code>-</code> with those without is not valid syntax and will be
3645 rejected during server startup by the syntax check with an abort.</p>
3648 <p>For example, without any <code>+</code> and <code>-</code> symbols:</p>
3650 <pre class="prettyprint lang-config"><Directory "/web/docs">
3651 Options Indexes FollowSymLinks
3654 <Directory "/web/docs/spec">
3656 </Directory></pre>
3659 <p>then only <code>Includes</code> will be set for the
3660 <code>/web/docs/spec</code> directory. However if the second
3661 <code class="directive">Options</code> directive uses the <code>+</code> and
3662 <code>-</code> symbols:</p>
3664 <pre class="prettyprint lang-config"><Directory "/web/docs">
3665 Options Indexes FollowSymLinks
3668 <Directory "/web/docs/spec">
3669 Options +Includes -Indexes
3670 </Directory></pre>
3673 <p>then the options <code>FollowSymLinks</code> and
3674 <code>Includes</code> are set for the <code>/web/docs/spec</code>
3677 <div class="note"><h3>Note</h3>
3678 <p>Using <code>-IncludesNOEXEC</code> or
3679 <code>-Includes</code> disables server-side includes completely
3680 regardless of the previous setting.</p>
3683 <p>The default in the absence of any other settings is
3684 <code>FollowSymlinks</code>.</p>
3687 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3688 <div class="directive-section"><h2><a name="Protocol" id="Protocol">Protocol</a> <a name="protocol" id="protocol">Directive</a></h2>
3689 <table class="directive">
3690 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocol for a listening socket</td></tr>
3691 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocol <var>protocol</var></code></td></tr>
3692 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3693 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3694 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3695 <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>
3697 <p>This directive specifies the protocol used for a specific listening socket.
3698 The protocol is used to determine which module should handle a request and
3699 to apply protocol specific optimizations with the <code class="directive">AcceptFilter</code>
3702 <p>You only need to set the protocol if you are running on non-standard ports;
3703 otherwise, <code>http</code> is assumed for port 80 and <code>https</code>
3706 <p>For example, if you are running <code>https</code> on a non-standard port,
3707 specify the protocol explicitly:</p>
3709 <pre class="prettyprint lang-config">Protocol https</pre>
3712 <p>You can also specify the protocol using the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code> directive.</p>
3716 <li><code class="directive"><a href="#acceptfilter">AcceptFilter</a></code></li>
3717 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
3720 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3721 <div class="directive-section"><h2><a name="Protocols" id="Protocols">Protocols</a> <a name="protocols" id="protocols">Directive</a></h2>
3722 <table class="directive">
3723 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocols available for a server/virtual host</td></tr>
3724 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocols <var>protocol</var> ...</code></td></tr>
3725 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Protocols http/1.1</code></td></tr>
3726 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3727 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3728 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3729 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3731 <p>This directive specifies the list of protocols supported for a
3732 server/virtual host. The list determines the allowed protocols
3733 a client may negotiate for this server/host.</p>
3735 <p>You need to set protocols if you want to extend the available
3736 protocols for a server/host. By default, only the http/1.1 protocol
3737 (which includes the compatibility with 1.0 and 0.9 clients) is
3740 <p>For example, if you want to support HTTP/2 for a server with TLS,
3743 <pre class="prettyprint lang-config">Protocols h2 http/1.1</pre>
3746 <p>Valid protocols are <code>http/1.1</code> for http and https connections,
3747 <code>h2</code> on https connections and <code>h2c</code> for http
3748 connections. Modules may enable more protocols.</p>
3750 <p>It is safe to specify protocols that are unavailable/disabled. Such
3751 protocol names will simply be ignored.</p>
3753 <p>Protocols specified in base servers are inherited for virtual hosts
3754 only if the virtual host has no own Protocols directive. Or, the other
3755 way around, Protocols directives in virtual hosts replace any
3756 such directive in the base server.
3762 <li><code class="directive"><a href="#protocolshonororder">ProtocolsHonorOrder</a></code></li>
3765 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3766 <div class="directive-section"><h2><a name="ProtocolsHonorOrder" id="ProtocolsHonorOrder">ProtocolsHonorOrder</a> <a name="protocolshonororder" id="protocolshonororder">Directive</a></h2>
3767 <table class="directive">
3768 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines if order of Protocols determines precedence during negotiation</td></tr>
3769 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProtocolsHonorOrder On|Off</code></td></tr>
3770 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProtocolsHonorOrder On</code></td></tr>
3771 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3772 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3773 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3774 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3776 <p>This directive specifies if the server should honor the order in which
3777 the <code class="directive">Protocols</code> directive lists protocols.</p>
3779 <p>If configured Off, the client supplied list order of protocols has
3780 precedence over the order in the server configuration.</p>
3782 <p>With <code class="directive">ProtocolsHonorOrder</code> set to <code>on</code>
3783 (default), the client ordering does not matter and only the ordering
3784 in the server settings influences the outcome of the protocol
3790 <li><code class="directive"><a href="#protocols">Protocols</a></code></li>
3793 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3794 <div class="directive-section"><h2><a name="QualifyRedirectURL" id="QualifyRedirectURL">QualifyRedirectURL</a> <a name="qualifyredirecturl" id="qualifyredirecturl">Directive</a></h2>
3795 <table class="directive">
3796 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls whether the REDIRECT_URL environment variable is
3797 fully qualified</td></tr>
3798 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>QualifyRedirectURL ON|OFF</code></td></tr>
3799 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>QualifyRedirectURL OFF</code></td></tr>
3800 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3801 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3802 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3803 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3804 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directive supported in 2.4.18 and later. 2.4.17 acted
3805 as if 'QualifyRedirectURL ON' was configured.</td></tr>
3807 <p>This directive controls whether the server will ensure that the
3808 REDIRECT_URL environment variable is fully qualified. By default,
3809 the variable contains the verbatim URL requested by the client,
3810 such as "/index.html". With <code class="directive"><a href="#qualifyredirecturl on">QualifyRedirectURL ON</a></code>, the same request would result in a
3811 value such as "http://www.example.com/index.html".</p>
3812 <p>Even without this directive set, when a request is issued against a
3813 fully qualified URL, REDIRECT_URL will remain fully qualified.
3817 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3818 <div class="directive-section"><h2><a name="RegisterHttpMethod" id="RegisterHttpMethod">RegisterHttpMethod</a> <a name="registerhttpmethod" id="registerhttpmethod">Directive</a></h2>
3819 <table class="directive">
3820 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Register non-standard HTTP methods</td></tr>
3821 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RegisterHttpMethod <var>method</var> [<var>method</var> [...]]</code></td></tr>
3822 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3823 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3824 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3826 <p>HTTP Methods that are not conforming to the relvant RFCs are normally
3827 rejected by request processing in Apache HTTPD. To avoid this, modules
3828 can register non-standard HTTP methods they support.
3829 The <code class="directive">RegisterHttpMethod</code> allows to register such
3830 methods manually. This can be useful if such methods are forwarded
3831 for external processing, e.g. to a CGI script.</p>
3834 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3835 <div class="directive-section"><h2><a name="RLimitCPU" id="RLimitCPU">RLimitCPU</a> <a name="rlimitcpu" id="rlimitcpu">Directive</a></h2>
3836 <table class="directive">
3837 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the CPU consumption of processes launched
3838 by Apache httpd children</td></tr>
3839 <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>
3840 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3841 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3842 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3843 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3844 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3846 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3847 resource limit for all processes and the second parameter sets
3848 the maximum resource limit. Either parameter can be a number,
3849 or <code>max</code> to indicate to the server that the limit should
3850 be set to the maximum allowed by the operating system
3851 configuration. Raising the maximum resource limit requires that
3852 the server is running as <code>root</code> or in the initial startup
3855 <p>This applies to processes forked from Apache httpd children
3856 servicing requests, not the Apache httpd children themselves. This
3857 includes CGI scripts and SSI exec commands, but not any
3858 processes forked from the Apache httpd parent, such as piped
3861 <p>CPU resource limits are expressed in seconds per
3866 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
3867 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3870 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3871 <div class="directive-section"><h2><a name="RLimitMEM" id="RLimitMEM">RLimitMEM</a> <a name="rlimitmem" id="rlimitmem">Directive</a></h2>
3872 <table class="directive">
3873 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the memory consumption of processes launched
3874 by Apache httpd children</td></tr>
3875 <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>
3876 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3877 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3878 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3879 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3880 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3882 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3883 resource limit for all processes and the second parameter sets
3884 the maximum resource limit. Either parameter can be a number,
3885 or <code>max</code> to indicate to the server that the limit should
3886 be set to the maximum allowed by the operating system
3887 configuration. Raising the maximum resource limit requires that
3888 the server is running as <code>root</code> or in the initial startup
3891 <p>This applies to processes forked from Apache httpd children
3892 servicing requests, not the Apache httpd children themselves. This
3893 includes CGI scripts and SSI exec commands, but not any
3894 processes forked from the Apache httpd parent, such as piped
3897 <p>Memory resource limits are expressed in bytes per
3902 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
3903 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3906 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3907 <div class="directive-section"><h2><a name="RLimitNPROC" id="RLimitNPROC">RLimitNPROC</a> <a name="rlimitnproc" id="rlimitnproc">Directive</a></h2>
3908 <table class="directive">
3909 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of processes that can be launched by
3910 processes launched by Apache httpd children</td></tr>
3911 <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>
3912 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3913 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3914 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3915 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3916 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3918 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3919 resource limit for all processes, and the second parameter sets
3920 the maximum resource limit. Either parameter can be a number,
3921 or <code>max</code> to indicate to the server that the limit
3922 should be set to the maximum allowed by the operating system
3923 configuration. Raising the maximum resource limit requires that
3924 the server is running as <code>root</code> or in the initial startup
3927 <p>This applies to processes forked from Apache httpd children
3928 servicing requests, not the Apache httpd children themselves. This
3929 includes CGI scripts and SSI exec commands, but not any
3930 processes forked from the Apache httpd parent, such as piped
3933 <p>Process limits control the number of processes per user.</p>
3935 <div class="note"><h3>Note</h3>
3936 <p>If CGI processes are <strong>not</strong> running
3937 under user ids other than the web server user id, this directive
3938 will limit the number of processes that the server itself can
3939 create. Evidence of this situation will be indicated by
3940 <strong><code>cannot fork</code></strong> messages in the
3941 <code>error_log</code>.</p>
3946 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
3947 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
3950 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3951 <div class="directive-section"><h2><a name="ScriptInterpreterSource" id="ScriptInterpreterSource">ScriptInterpreterSource</a> <a name="scriptinterpretersource" id="scriptinterpretersource">Directive</a></h2>
3952 <table class="directive">
3953 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
3955 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ScriptInterpreterSource Registry|Registry-Strict|Script</code></td></tr>
3956 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ScriptInterpreterSource Script</code></td></tr>
3957 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3958 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3959 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3960 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3961 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Win32 only.</td></tr>
3963 <p>This directive is used to control how Apache httpd finds the
3964 interpreter used to run CGI scripts. The default setting is
3965 <code>Script</code>. This causes Apache httpd to use the interpreter pointed to
3966 by the shebang line (first line, starting with <code>#!</code>) in the
3967 script. On Win32 systems this line usually looks like:</p>
3969 <pre class="prettyprint lang-perl">#!C:/Perl/bin/perl.exe</pre>
3972 <p>or, if <code>perl</code> is in the <code>PATH</code>, simply:</p>
3974 <pre class="prettyprint lang-perl">#!perl</pre>
3977 <p>Setting <code>ScriptInterpreterSource Registry</code> will
3978 cause the Windows Registry tree <code>HKEY_CLASSES_ROOT</code> to be
3979 searched using the script file extension (e.g., <code>.pl</code>) as a
3980 search key. The command defined by the registry subkey
3981 <code>Shell\ExecCGI\Command</code> or, if it does not exist, by the subkey
3982 <code>Shell\Open\Command</code> is used to open the script file. If the
3983 registry keys cannot be found, Apache httpd falls back to the behavior of the
3984 <code>Script</code> option.</p>
3986 <div class="warning"><h3>Security</h3>
3987 <p>Be careful when using <code>ScriptInterpreterSource
3988 Registry</code> with <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories, because
3989 Apache httpd will try to execute <strong>every</strong> file within this
3990 directory. The <code>Registry</code> setting may cause undesired
3991 program calls on files which are typically not executed. For
3992 example, the default open command on <code>.htm</code> files on
3993 most Windows systems will execute Microsoft Internet Explorer, so
3994 any HTTP request for an <code>.htm</code> file existing within the
3995 script directory would start the browser in the background on the
3996 server. This is a good way to crash your system within a minute or
4000 <p>The option <code>Registry-Strict</code> which is new in Apache HTTP Server
4001 2.0 does the same thing as <code>Registry</code> but uses only the
4002 subkey <code>Shell\ExecCGI\Command</code>. The
4003 <code>ExecCGI</code> key is not a common one. It must be
4004 configured manually in the windows registry and hence prevents
4005 accidental program calls on your system.</p>
4008 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4009 <div class="directive-section"><h2><a name="SeeRequestTail" id="SeeRequestTail">SeeRequestTail</a> <a name="seerequesttail" id="seerequesttail">Directive</a></h2>
4010 <table class="directive">
4011 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine if mod_status displays the first 63 characters
4012 of a request or the last 63, assuming the request itself is greater than
4014 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SeeRequestTail On|Off</code></td></tr>
4015 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SeeRequestTail Off</code></td></tr>
4016 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4017 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4018 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4020 <p>mod_status with <code>ExtendedStatus On</code>
4021 displays the actual request being handled.
4022 For historical purposes, only 63 characters of the request
4023 are actually stored for display purposes. This directive
4024 controls whether the 1st 63 characters are stored (the previous
4025 behavior and the default) or if the last 63 characters are. This
4026 is only applicable, of course, if the length of the request is
4027 64 characters or greater.</p>
4029 <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:
4032 <table class="bordered">
4034 <th>Off (default)</th>
4035 <td>GET /disk1/storage/apache/htdocs/images/imagestore1/food/apples</td>
4039 <td>orage/apache/htdocs/images/imagestore1/food/apples.jpg HTTP/1.1</td>
4045 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4046 <div class="directive-section"><h2><a name="ServerAdmin" id="ServerAdmin">ServerAdmin</a> <a name="serveradmin" id="serveradmin">Directive</a></h2>
4047 <table class="directive">
4048 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Email address that the server includes in error
4049 messages sent to the client</td></tr>
4050 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAdmin <var>email-address</var>|<var>URL</var></code></td></tr>
4051 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4052 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4053 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4055 <p>The <code class="directive">ServerAdmin</code> sets the contact address
4056 that the server includes in any error messages it returns to the
4057 client. If the <code>httpd</code> doesn't recognize the supplied argument
4059 assumes, that it's an <var>email-address</var> and prepends it with
4060 <code>mailto:</code> in hyperlink targets. However, it's recommended to
4061 actually use an email address, since there are a lot of CGI scripts that
4062 make that assumption. If you want to use an URL, it should point to another
4063 server under your control. Otherwise users may not be able to contact you in
4066 <p>It may be worth setting up a dedicated address for this, e.g.</p>
4068 <pre class="prettyprint lang-config">ServerAdmin www-admin@foo.example.com</pre>
4070 <p>as users do not always mention that they are talking about the
4074 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4075 <div class="directive-section"><h2><a name="ServerAlias" id="ServerAlias">ServerAlias</a> <a name="serveralias" id="serveralias">Directive</a></h2>
4076 <table class="directive">
4077 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Alternate names for a host used when matching requests
4078 to name-virtual hosts</td></tr>
4079 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAlias <var>hostname</var> [<var>hostname</var>] ...</code></td></tr>
4080 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4081 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4082 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4084 <p>The <code class="directive">ServerAlias</code> directive sets the
4085 alternate names for a host, for use with <a href="../vhosts/name-based.html">name-based virtual hosts</a>. The
4086 <code class="directive">ServerAlias</code> may include wildcards, if appropriate.</p>
4088 <pre class="prettyprint lang-config"><VirtualHost *:80>
4089 ServerName server.example.com
4090 ServerAlias server server2.example.com server2
4091 ServerAlias *.example.com
4092 UseCanonicalName Off
4094 </VirtualHost></pre>
4097 <p>Name-based virtual hosts for the best-matching set of <code class="directive"><a href="#virtualhost"><virtualhost></a></code>s are processed
4098 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
4099 (nor for ServerName vs. ServerAlias). </p>
4101 <p>The complete list of names in the <code class="directive">VirtualHost</code>
4102 directive are treated just like a (non wildcard)
4103 <code class="directive">ServerAlias</code>.</p>
4108 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4109 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4112 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4113 <div class="directive-section"><h2><a name="ServerName" id="ServerName">ServerName</a> <a name="servername" id="servername">Directive</a></h2>
4114 <table class="directive">
4115 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Hostname and port that the server uses to identify
4117 <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>
4118 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4119 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4120 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4122 <p>The <code class="directive">ServerName</code> directive sets the
4123 request scheme, hostname and port that the server uses to identify itself.
4126 <p><code class="directive">ServerName</code> is used (possibly
4127 in conjunction with <code class="directive">ServerAlias</code>) to uniquely
4128 identify a virtual host, when using <a href="../vhosts/name-based.html">name-based virtual hosts</a>.</p>
4130 <p>Additionally, this is used when
4131 creating self-referential redirection URLs when
4132 <code class="directive">UseCanonicalName</code> is set to a non-default
4135 <p>For example, if the name of the
4136 machine hosting the web server is <code>simple.example.com</code>,
4137 but the machine also has the DNS alias <code>www.example.com</code>
4138 and you wish the web server to be so identified, the following
4139 directive should be used:</p>
4141 <pre class="prettyprint lang-config">ServerName www.example.com</pre>
4144 <p>The <code class="directive">ServerName</code> directive
4145 may appear anywhere within the definition of a server. However,
4146 each appearance overrides the previous appearance (within that
4149 <p>If no <code class="directive">ServerName</code> is specified, the
4150 server attempts to deduce the client visible hostname by first asking
4151 the operating system for the system hostname, and if that fails,
4152 performing a reverse lookup on an IP address present on the system.</p>
4154 <p>If no port is specified in the
4155 <code class="directive">ServerName</code>, then the server will use the
4156 port from the incoming request. For optimal reliability and
4157 predictability, you should specify an explicit hostname and port
4158 using the <code class="directive">ServerName</code> directive.</p>
4160 <p>If you are using <a href="../vhosts/name-based.html">name-based virtual hosts</a>,
4161 the <code class="directive">ServerName</code> inside a
4162 <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
4163 section specifies what hostname must appear in the request's
4164 <code>Host:</code> header to match this virtual host.</p>
4166 <p>Sometimes, the server runs behind a device that processes SSL,
4167 such as a reverse proxy, load balancer or SSL offload
4168 appliance. When this is the case, specify the
4169 <code>https://</code> scheme and the port number to which the
4170 clients connect in the <code class="directive">ServerName</code> directive
4171 to make sure that the server generates the correct
4172 self-referential URLs.
4175 <p>See the description of the
4176 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> and
4177 <code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code> directives for
4178 settings which determine whether self-referential URLs (e.g., by the
4179 <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> module) will refer to the
4180 specified port, or to the port number given in the client's request.
4183 <div class="warning">
4184 <p>Failure to set <code class="directive">ServerName</code> to a name that
4185 your server can resolve to an IP address will result in a startup
4186 warning. <code>httpd</code> will then use whatever hostname it can
4187 determine, using the system's <code>hostname</code> command. This
4188 will almost never be the hostname you actually want.</p>
4189 <div class="example"><p><code>
4190 httpd: Could not reliably determine the server's fully qualified domain name, using rocinante.local for ServerName
4197 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4198 Apache HTTP Server</a></li>
4199 <li><a href="../vhosts/">Apache HTTP Server virtual host
4200 documentation</a></li>
4201 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4202 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4203 <li><code class="directive"><a href="#serveralias">ServerAlias</a></code></li>
4206 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4207 <div class="directive-section"><h2><a name="ServerPath" id="ServerPath">ServerPath</a> <a name="serverpath" id="serverpath">Directive</a></h2>
4208 <table class="directive">
4209 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Legacy URL pathname for a name-based virtual host that
4210 is accessed by an incompatible browser</td></tr>
4211 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerPath <var>URL-path</var></code></td></tr>
4212 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4213 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4214 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4216 <p>The <code class="directive">ServerPath</code> directive sets the legacy
4217 URL pathname for a host, for use with <a href="../vhosts/">name-based virtual hosts</a>.</p>
4221 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4224 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4225 <div class="directive-section"><h2><a name="ServerRoot" id="ServerRoot">ServerRoot</a> <a name="serverroot" id="serverroot">Directive</a></h2>
4226 <table class="directive">
4227 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server installation</td></tr>
4228 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerRoot <var>directory-path</var></code></td></tr>
4229 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerRoot /usr/local/apache</code></td></tr>
4230 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4231 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4232 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4234 <p>The <code class="directive">ServerRoot</code> directive sets the
4235 directory in which the server lives. Typically it will contain the
4236 subdirectories <code>conf/</code> and <code>logs/</code>. Relative
4237 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
4238 relative to this directory.</p>
4240 <pre class="prettyprint lang-config">ServerRoot "/home/httpd"</pre>
4243 <p>The default location of <code class="directive">ServerRoot</code> may be
4244 modified by using the <code>--prefix</code> argument to
4245 <a href="../programs/configure.html"><code>configure</code></a>, and
4246 most third-party distributions of the server have a different
4247 default location from the one listed above.</p>
4252 <li><a href="../invoking.html">the <code>-d</code>
4253 option to <code>httpd</code></a></li>
4254 <li><a href="../misc/security_tips.html#serverroot">the
4255 security tips</a> for information on how to properly set
4256 permissions on the <code class="directive">ServerRoot</code></li>
4259 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4260 <div class="directive-section"><h2><a name="ServerSignature" id="ServerSignature">ServerSignature</a> <a name="serversignature" id="serversignature">Directive</a></h2>
4261 <table class="directive">
4262 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the footer on server-generated documents</td></tr>
4263 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerSignature On|Off|EMail</code></td></tr>
4264 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerSignature Off</code></td></tr>
4265 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4266 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
4267 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4268 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4270 <p>The <code class="directive">ServerSignature</code> directive allows the
4271 configuration of a trailing footer line under server-generated
4272 documents (error messages, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> ftp directory
4273 listings, <code class="module"><a href="../mod/mod_info.html">mod_info</a></code> output, ...). The reason why you
4274 would want to enable such a footer line is that in a chain of proxies,
4275 the user often has no possibility to tell which of the chained servers
4276 actually produced a returned error message.</p>
4278 <p>The <code>Off</code>
4279 setting, which is the default, suppresses the footer line (and is
4280 therefore compatible with the behavior of Apache-1.2 and
4281 below). The <code>On</code> setting simply adds a line with the
4282 server version number and <code class="directive"><a href="#servername">ServerName</a></code> of the serving virtual host,
4283 and the <code>EMail</code> setting additionally creates a
4284 "mailto:" reference to the <code class="directive"><a href="#serveradmin">ServerAdmin</a></code> of the referenced
4287 <p>After version 2.0.44, the details of the server version number
4288 presented are controlled by the <code class="directive"><a href="#servertokens">ServerTokens</a></code> directive.</p>
4292 <li><code class="directive"><a href="#servertokens">ServerTokens</a></code></li>
4295 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4296 <div class="directive-section"><h2><a name="ServerTokens" id="ServerTokens">ServerTokens</a> <a name="servertokens" id="servertokens">Directive</a></h2>
4297 <table class="directive">
4298 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the <code>Server</code> HTTP response
4300 <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>
4301 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerTokens Full</code></td></tr>
4302 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</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>This directive controls whether <code>Server</code> response
4307 header field which is sent back to clients includes a
4308 description of the generic OS-type of the server as well as
4309 information about compiled-in modules.</p>
4312 <dt><code>ServerTokens Full</code> (or not specified)</dt>
4314 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4315 (Unix) PHP/4.2.2 MyMod/1.2</code></dd>
4317 <dt><code>ServerTokens Prod[uctOnly]</code></dt>
4319 <dd>Server sends (<em>e.g.</em>): <code>Server:
4322 <dt><code>ServerTokens Major</code></dt>
4324 <dd>Server sends (<em>e.g.</em>): <code>Server:
4325 Apache/2</code></dd>
4327 <dt><code>ServerTokens Minor</code></dt>
4329 <dd>Server sends (<em>e.g.</em>): <code>Server:
4330 Apache/2.4</code></dd>
4332 <dt><code>ServerTokens Min[imal]</code></dt>
4334 <dd>Server sends (<em>e.g.</em>): <code>Server:
4335 Apache/2.4.2</code></dd>
4337 <dt><code>ServerTokens OS</code></dt>
4339 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4344 <p>This setting applies to the entire server, and cannot be
4345 enabled or disabled on a virtualhost-by-virtualhost basis.</p>
4347 <p>After version 2.0.44, this directive also controls the
4348 information presented by the <code class="directive"><a href="#serversignature">ServerSignature</a></code> directive.</p>
4350 <div class="note">Setting <code class="directive">ServerTokens</code> to less than
4351 <code>minimal</code> is not recommended because it makes it more
4352 difficult to debug interoperational problems. Also note that
4353 disabling the Server: header does nothing at all to make your
4354 server more secure. The idea of "security through obscurity"
4355 is a myth and leads to a false sense of safety.</div>
4359 <li><code class="directive"><a href="#serversignature">ServerSignature</a></code></li>
4362 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4363 <div class="directive-section"><h2><a name="SetHandler" id="SetHandler">SetHandler</a> <a name="sethandler" id="sethandler">Directive</a></h2>
4364 <table class="directive">
4365 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be processed by a
4367 <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>
4368 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4369 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4370 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4371 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4372 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4374 <p>When placed into an <code>.htaccess</code> file or a
4375 <code class="directive"><a href="#directory"><Directory></a></code> or
4376 <code class="directive"><a href="#location"><Location></a></code>
4377 section, this directive forces all matching files to be parsed
4378 through the <a href="../handler.html">handler</a> given by
4379 <var>handler-name</var>. For example, if you had a directory you
4380 wanted to be parsed entirely as imagemap rule files, regardless
4381 of extension, you might put the following into an
4382 <code>.htaccess</code> file in that directory:</p>
4384 <pre class="prettyprint lang-config">SetHandler imap-file</pre>
4387 <p>Another example: if you wanted to have the server display a
4388 status report whenever a URL of
4389 <code>http://servername/status</code> was called, you might put
4390 the following into <code>httpd.conf</code>:</p>
4392 <pre class="prettyprint lang-config"><Location "/status">
4393 SetHandler server-status
4394 </Location></pre>
4397 <p>You could also use this directive to configure a particular
4398 handler for files with a particular file extension. For example:</p>
4400 <pre class="prettyprint lang-config"><FilesMatch "\.php$">
4401 SetHandler application/x-httpd-php
4402 </FilesMatch></pre>
4405 <p>String-valued expressions can be used to reference per-request
4406 variables, including backreferences to named regular expressions:</p>
4408 <pre class="prettyprint lang-config"><LocationMatch ^/app/(?<sub>[^/]+)/>
4409 SetHandler "proxy:unix:/var/run/app_%{env:MATCH_sub}.sock|fcgi://localhost:8080"
4410 </LocationMatch></pre>
4413 <p>You can override an earlier defined <code class="directive">SetHandler</code>
4414 directive by using the value <code>None</code>.</p>
4416 <div class="note"><h3>Note</h3>
4417 <p>Because <code class="directive">SetHandler</code> overrides default handlers,
4418 normal behavior such as handling of URLs ending in a slash (/) as
4419 directories or index files is suppressed.</p></div>
4423 <li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li>
4426 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4427 <div class="directive-section"><h2><a name="SetInputFilter" id="SetInputFilter">SetInputFilter</a> <a name="setinputfilter" id="setinputfilter">Directive</a></h2>
4428 <table class="directive">
4429 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process client requests and POST
4431 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetInputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4432 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4433 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4434 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4435 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4437 <p>The <code class="directive">SetInputFilter</code> directive sets the
4438 filter or filters which will process client requests and POST
4439 input when they are received by the server. This is in addition to
4440 any filters defined elsewhere, including the
4441 <code class="directive"><a href="../mod/mod_mime.html#addinputfilter">AddInputFilter</a></code>
4444 <p>If more than one filter is specified, they must be separated
4445 by semicolons in the order in which they should process the
4450 <li><a href="../filter.html">Filters</a> documentation</li>
4453 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4454 <div class="directive-section"><h2><a name="SetOutputFilter" id="SetOutputFilter">SetOutputFilter</a> <a name="setoutputfilter" id="setoutputfilter">Directive</a></h2>
4455 <table class="directive">
4456 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process responses from the
4458 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetOutputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4459 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4460 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4461 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4462 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4464 <p>The <code class="directive">SetOutputFilter</code> directive sets the filters
4465 which will process responses from the server before they are
4466 sent to the client. This is in addition to any filters defined
4467 elsewhere, including the
4468 <code class="directive"><a href="../mod/mod_mime.html#addoutputfilter">AddOutputFilter</a></code>
4471 <p>For example, the following configuration will process all files
4472 in the <code>/www/data/</code> directory for server-side
4475 <pre class="prettyprint lang-config"><Directory "/www/data/">
4476 SetOutputFilter INCLUDES
4477 </Directory></pre>
4480 <p>If more than one filter is specified, they must be separated
4481 by semicolons in the order in which they should process the
4486 <li><a href="../filter.html">Filters</a> documentation</li>
4489 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4490 <div class="directive-section"><h2><a name="TimeOut" id="TimeOut">TimeOut</a> <a name="timeout" id="timeout">Directive</a></h2>
4491 <table class="directive">
4492 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for
4493 certain events before failing a request</td></tr>
4494 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TimeOut <var>seconds</var></code></td></tr>
4495 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TimeOut 60</code></td></tr>
4496 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4497 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4498 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4500 <p>The <code class="directive">TimeOut</code> directive defines the length
4501 of time Apache httpd will wait for I/O in various circumstances:</p>
4504 <li><p>When reading data from the client, the length of time to
4505 wait for a TCP packet to arrive if the read buffer is
4507 <p> For initial data on a new connection, this directive doesn't
4508 take effect until after any configured <code class="directive"><a href="#acceptfilter">
4509 AcceptFilter</a></code> has passed the new connection to the server.</p>
4512 <li>When writing data to the client, the length of time to wait
4513 for an acknowledgement of a packet if the send buffer is
4516 <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>,
4517 the length of time to wait for output from a CGI script.</li>
4519 <li>In <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>, the length of time to
4520 wait for output from a filtering process.</li>
4522 <li>In <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, the default timeout value if
4523 <code class="directive"><a href="../mod/mod_proxy.html#proxytimeout">ProxyTimeout</a></code> is not
4529 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4530 <div class="directive-section"><h2><a name="TraceEnable" id="TraceEnable">TraceEnable</a> <a name="traceenable" id="traceenable">Directive</a></h2>
4531 <table class="directive">
4532 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines the behavior on <code>TRACE</code> requests</td></tr>
4533 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TraceEnable <var>[on|off|extended]</var></code></td></tr>
4534 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TraceEnable on</code></td></tr>
4535 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4536 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4537 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4539 <p>This directive overrides the behavior of <code>TRACE</code> for both
4540 the core server and <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. The default
4541 <code>TraceEnable on</code> permits <code>TRACE</code> requests per
4542 RFC 2616, which disallows any request body to accompany the request.
4543 <code>TraceEnable off</code> causes the core server and
4544 <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> to return a <code>405</code> (Method not
4545 allowed) error to the client.</p>
4547 <p>Finally, for testing and diagnostic purposes only, request
4548 bodies may be allowed using the non-compliant <code>TraceEnable
4549 extended</code> directive. The core (as an origin server) will
4550 restrict the request body to 64k (plus 8k for chunk headers if
4551 <code>Transfer-Encoding: chunked</code> is used). The core will
4552 reflect the full headers and all chunk headers with the response
4553 body. As a proxy server, the request body is not restricted to 64k.</p>
4555 <div class="note"><h3>Note</h3>
4556 <p>Despite claims to the contrary, <code>TRACE</code> is not
4557 a security vulnerability, and there is no viable reason for
4558 it to be disabled. Doing so necessarily makes your server
4563 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4564 <div class="directive-section"><h2><a name="UnDefine" id="UnDefine">UnDefine</a> <a name="undefine" id="undefine">Directive</a></h2>
4565 <table class="directive">
4566 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Undefine the existence of a variable</td></tr>
4567 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UnDefine <var>parameter-name</var></code></td></tr>
4568 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4569 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4570 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4572 <p>Undoes the effect of a <code class="directive"><a href="#define">Define</a></code> or
4573 of passing a <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</p>
4574 <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
4575 <code>-D</code> arguments in any startup scripts.</p>
4576 <p>While this directive is supported in virtual host context,
4577 the changes it makes are visible to any later configuration
4578 directives, beyond any enclosing virtual host.</p>
4581 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4582 <div class="directive-section"><h2><a name="UseCanonicalName" id="UseCanonicalName">UseCanonicalName</a> <a name="usecanonicalname" id="usecanonicalname">Directive</a></h2>
4583 <table class="directive">
4584 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own name and
4586 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalName On|Off|DNS</code></td></tr>
4587 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalName Off</code></td></tr>
4588 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4589 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4590 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4592 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4593 URL -- that is, a URL that refers back to the same server. With
4594 <code>UseCanonicalName On</code> Apache httpd will use the hostname and port
4595 specified in the <code class="directive"><a href="#servername">ServerName</a></code>
4596 directive to construct the canonical name for the server. This name
4597 is used in all self-referential URLs, and for the values of
4598 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in CGIs.</p>
4600 <p>With <code>UseCanonicalName Off</code> Apache httpd will form
4601 self-referential URLs using the hostname and port supplied by
4602 the client if any are supplied (otherwise it will use the
4603 canonical name, as defined above). These values are the same
4604 that are used to implement <a href="../vhosts/name-based.html">name-based virtual hosts</a>
4605 and are available with the same clients. The CGI variables
4606 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
4607 constructed from the client supplied values as well.</p>
4609 <p>An example where this may be useful is on an intranet server
4610 where you have users connecting to the machine using short
4611 names such as <code>www</code>. You'll notice that if the users
4612 type a shortname and a URL which is a directory, such as
4613 <code>http://www/splat</code>, <em>without the trailing
4614 slash</em>, then Apache httpd will redirect them to
4615 <code>http://www.example.com/splat/</code>. If you have
4616 authentication enabled, this will cause the user to have to
4617 authenticate twice (once for <code>www</code> and once again
4618 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">
4619 the FAQ on this subject for more information</a>). But if
4620 <code class="directive">UseCanonicalName</code> is set <code>Off</code>, then
4621 Apache httpd will redirect to <code>http://www/splat/</code>.</p>
4623 <p>There is a third option, <code>UseCanonicalName DNS</code>,
4624 which is intended for use with mass IP-based virtual hosting to
4625 support ancient clients that do not provide a
4626 <code>Host:</code> header. With this option, Apache httpd does a
4627 reverse DNS lookup on the server IP address that the client
4628 connected to in order to work out self-referential URLs.</p>
4630 <div class="warning"><h3>Warning</h3>
4631 <p>If CGIs make assumptions about the values of <code>SERVER_NAME</code>,
4632 they may be broken by this option. The client is essentially free
4633 to give whatever value they want as a hostname. But if the CGI is
4634 only using <code>SERVER_NAME</code> to construct self-referential URLs,
4635 then it should be just fine.</p>
4640 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4641 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4642 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4645 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4646 <div class="directive-section"><h2><a name="UseCanonicalPhysicalPort" id="UseCanonicalPhysicalPort">UseCanonicalPhysicalPort</a> <a name="usecanonicalphysicalport" id="usecanonicalphysicalport">Directive</a></h2>
4647 <table class="directive">
4648 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own port</td></tr>
4649 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalPhysicalPort On|Off</code></td></tr>
4650 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalPhysicalPort Off</code></td></tr>
4651 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4652 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4653 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4655 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4656 URL -- that is, a URL that refers back to the same server. With
4657 <code>UseCanonicalPhysicalPort On</code>, Apache httpd will, when
4658 constructing the canonical port for the server to honor
4659 the <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> directive,
4660 provide the actual physical port number being used by this request
4661 as a potential port. With <code>UseCanonicalPhysicalPort Off</code>,
4662 Apache httpd will not ever use the actual physical port number, instead
4663 relying on all configured information to construct a valid port number.</p>
4665 <div class="note"><h3>Note</h3>
4666 <p>The ordering of the lookup when the physical port is used is as
4669 <dt><code>UseCanonicalName On</code></dt>
4672 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4673 <li>Physical port</li>
4674 <li>Default port</li>
4677 <dt><code>UseCanonicalName Off | DNS</code></dt>
4680 <li>Parsed port from <code>Host:</code> header</li>
4681 <li>Physical port</li>
4682 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4683 <li>Default port</li>
4688 <p>With <code>UseCanonicalPhysicalPort Off</code>, the
4689 physical ports are removed from the ordering.</p>
4695 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4696 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4697 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4700 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4701 <div class="directive-section"><h2><a name="VirtualHost" id="VirtualHost"><VirtualHost></a> <a name="virtualhost" id="virtualhost">Directive</a></h2>
4702 <table class="directive">
4703 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only to a specific
4704 hostname or IP address</td></tr>
4705 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><VirtualHost
4706 <var>addr</var>[:<var>port</var>] [<var>addr</var>[:<var>port</var>]]
4707 ...> ... </VirtualHost></code></td></tr>
4708 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4709 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4710 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4712 <p><code class="directive"><VirtualHost></code> and
4713 <code></VirtualHost></code> are used to enclose a group of
4714 directives that will apply only to a particular virtual host. Any
4715 directive that is allowed in a virtual host context may be
4716 used. When the server receives a request for a document on a
4717 particular virtual host, it uses the configuration directives
4718 enclosed in the <code class="directive"><VirtualHost></code>
4719 section. <var>Addr</var> can be any of the following, optionally followed by
4720 a colon and a port number (or *):</p>
4723 <li>The IP address of the virtual host;</li>
4725 <li>A fully qualified domain name for the IP address of the
4726 virtual host (not recommended);</li>
4728 <li>The character <code>*</code>, which acts as a wildcard and matches
4729 any IP address.</li>
4731 <li>The string <code>_default_</code>, which is an alias for <code>*</code></li>
4735 <pre class="prettyprint lang-config"><VirtualHost 10.1.2.3:80>
4736 ServerAdmin webmaster@host.example.com
4737 DocumentRoot "/www/docs/host.example.com"
4738 ServerName host.example.com
4739 ErrorLog "logs/host.example.com-error_log"
4740 TransferLog "logs/host.example.com-access_log"
4741 </VirtualHost></pre>
4745 <p>IPv6 addresses must be specified in square brackets because
4746 the optional port number could not be determined otherwise. An
4747 IPv6 example is shown below:</p>
4749 <pre class="prettyprint lang-config"><VirtualHost [2001:db8::a00:20ff:fea7:ccea]:80>
4750 ServerAdmin webmaster@host.example.com
4751 DocumentRoot "/www/docs/host.example.com"
4752 ServerName host.example.com
4753 ErrorLog "logs/host.example.com-error_log"
4754 TransferLog "logs/host.example.com-access_log"
4755 </VirtualHost></pre>
4758 <p>Each Virtual Host must correspond to a different IP address,
4759 different port number, or a different host name for the server,
4760 in the former case the server machine must be configured to
4761 accept IP packets for multiple addresses. (If the machine does
4762 not have multiple network interfaces, then this can be
4763 accomplished with the <code>ifconfig alias</code> command -- if
4764 your OS supports it).</p>
4766 <div class="note"><h3>Note</h3>
4767 <p>The use of <code class="directive"><VirtualHost></code> does
4768 <strong>not</strong> affect what addresses Apache httpd listens on. You
4769 may need to ensure that Apache httpd is listening on the correct addresses
4770 using <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>.</p>
4773 <p>A <code class="directive"><a href="#servername">ServerName</a></code> should be
4774 specified inside each <code class="directive"><VirtualHost></code> block. If it is absent, the
4775 <code class="directive"><a href="#servername">ServerName</a></code> from the "main"
4776 server configuration will be inherited.</p>
4778 <p>When a request is received, the server first maps it to the best matching
4779 <code class="directive"><VirtualHost></code> based on the local
4780 IP address and port combination only. Non-wildcards have a higher
4781 precedence. If no match based on IP and port occurs at all, the
4782 "main" server configuration is used.</p>
4784 <p>If multiple virtual hosts contain the best matching IP address and port,
4785 the server selects from these virtual hosts the best match based on the
4786 requested hostname. If no matching name-based virtual host is found,
4787 then the first listed virtual host that matched the IP address will be
4788 used. As a consequence, the first listed virtual host for a given IP address
4789 and port combination is the default virtual host for that IP and port
4792 <div class="warning"><h3>Security</h3>
4793 <p>See the <a href="../misc/security_tips.html">security tips</a>
4794 document for details on why your security could be compromised if the
4795 directory where log files are stored is writable by anyone other
4796 than the user that starts the server.</p>
4801 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4802 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4803 Apache HTTP Server</a></li>
4804 <li><a href="../bind.html">Setting
4805 which addresses and ports Apache HTTP Server uses</a></li>
4806 <li><a href="../sections.html">How <Directory>, <Location>
4807 and <Files> sections work</a> for an explanation of how these
4808 different sections are combined when a request is received</li>
4811 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4812 <div class="directive-section"><h2><a name="Warning" id="Warning">Warning</a> <a name="warning" id="warning">Directive</a></h2>
4813 <table class="directive">
4814 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Warn from configuration parsing with a custom message</td></tr>
4815 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Warning <var>message</var></code></td></tr>
4816 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4817 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4818 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4819 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4821 <p>If an issue can be detected from within the configuration, this
4822 directive can be used to generate a custom warning message. The
4823 configuration parsing is not halted. The typical use is to check
4824 whether some user define options are set, and warn if not.</p>
4826 <pre class="prettyprint lang-config"># Example
4827 # tell when ReverseProxy is not set
4828 <IfDefine !ReverseProxy>
4829 Warning "reverse proxy is not started, hope this is okay!"
4832 <IfDefine ReverseProxy>
4833 # define custom proxy configuration
4834 </IfDefine></pre>
4840 <div class="bottomlang">
4841 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
4842 <a href="../en/mod/core.html" title="English"> en </a> |
4843 <a href="../es/mod/core.html" hreflang="es" rel="alternate" title="Español"> es </a> |
4844 <a href="../fr/mod/core.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
4845 <a href="../ja/mod/core.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
4846 <a href="../tr/mod/core.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
4847 </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>
4848 <script type="text/javascript"><!--//--><![CDATA[//><!--
4849 var comments_shortname = 'httpd';
4850 var comments_identifier = 'http://httpd.apache.org/docs/trunk/mod/core.html';
4852 if (w.location.hostname.toLowerCase() == "httpd.apache.org") {
4853 d.write('<div id="comments_thread"><\/div>');
4854 var s = d.createElement('script');
4855 s.type = 'text/javascript';
4857 s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier;
4858 (d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s);
4861 d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>');
4863 })(window, document);
4864 //--><!]]></script></div><div id="footer">
4865 <p class="apache">Copyright 2016 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
4866 <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></div><script type="text/javascript"><!--//--><![CDATA[//><!--
4867 if (typeof(prettyPrint) !== 'undefined') {