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8 <title>core - Apache HTTP Server</title>
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15 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
16 <p class="apache">Apache HTTP Server Version 2.3</p>
17 <img alt="" src="../images/feather.gif" /></div>
18 <div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
20 <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 2.3</a> > <a href="./">Modules</a></div>
21 <div id="page-content">
22 <div id="preamble"><h1>Apache Core Features</h1>
24 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
25 <a href="../en/mod/core.html" title="English"> en </a> |
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27 <a href="../ja/mod/core.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
28 <a href="../tr/mod/core.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
30 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Core Apache HTTP Server features that are always
32 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Core</td></tr></table>
34 <div id="quickview"><h3 class="directives">Directives</h3>
36 <li><img alt="" src="../images/down.gif" /> <a href="#acceptfilter">AcceptFilter</a></li>
37 <li><img alt="" src="../images/down.gif" /> <a href="#acceptpathinfo">AcceptPathInfo</a></li>
38 <li><img alt="" src="../images/down.gif" /> <a href="#accessfilename">AccessFileName</a></li>
39 <li><img alt="" src="../images/down.gif" /> <a href="#adddefaultcharset">AddDefaultCharset</a></li>
40 <li><img alt="" src="../images/down.gif" /> <a href="#allowencodedslashes">AllowEncodedSlashes</a></li>
41 <li><img alt="" src="../images/down.gif" /> <a href="#allowoverride">AllowOverride</a></li>
42 <li><img alt="" src="../images/down.gif" /> <a href="#cgimapextension">CGIMapExtension</a></li>
43 <li><img alt="" src="../images/down.gif" /> <a href="#contentdigest">ContentDigest</a></li>
44 <li><img alt="" src="../images/down.gif" /> <a href="#defaulttype">DefaultType</a></li>
45 <li><img alt="" src="../images/down.gif" /> <a href="#define">Define</a></li>
46 <li><img alt="" src="../images/down.gif" /> <a href="#directory"><Directory></a></li>
47 <li><img alt="" src="../images/down.gif" /> <a href="#directorymatch"><DirectoryMatch></a></li>
48 <li><img alt="" src="../images/down.gif" /> <a href="#documentroot">DocumentRoot</a></li>
49 <li><img alt="" src="../images/down.gif" /> <a href="#enablemmap">EnableMMAP</a></li>
50 <li><img alt="" src="../images/down.gif" /> <a href="#enablesendfile">EnableSendfile</a></li>
51 <li><img alt="" src="../images/down.gif" /> <a href="#errordocument">ErrorDocument</a></li>
52 <li><img alt="" src="../images/down.gif" /> <a href="#errorlog">ErrorLog</a></li>
53 <li><img alt="" src="../images/down.gif" /> <a href="#extendedstatus">ExtendedStatus</a></li>
54 <li><img alt="" src="../images/down.gif" /> <a href="#fileetag">FileETag</a></li>
55 <li><img alt="" src="../images/down.gif" /> <a href="#files"><Files></a></li>
56 <li><img alt="" src="../images/down.gif" /> <a href="#filesmatch"><FilesMatch></a></li>
57 <li><img alt="" src="../images/down.gif" /> <a href="#forcetype">ForceType</a></li>
58 <li><img alt="" src="../images/down.gif" /> <a href="#hostnamelookups">HostnameLookups</a></li>
59 <li><img alt="" src="../images/down.gif" /> <a href="#if"><If></a></li>
60 <li><img alt="" src="../images/down.gif" /> <a href="#ifdefine"><IfDefine></a></li>
61 <li><img alt="" src="../images/down.gif" /> <a href="#ifmodule"><IfModule></a></li>
62 <li><img alt="" src="../images/down.gif" /> <a href="#include">Include</a></li>
63 <li><img alt="" src="../images/down.gif" /> <a href="#keepalive">KeepAlive</a></li>
64 <li><img alt="" src="../images/down.gif" /> <a href="#keepalivetimeout">KeepAliveTimeout</a></li>
65 <li><img alt="" src="../images/down.gif" /> <a href="#limit"><Limit></a></li>
66 <li><img alt="" src="../images/down.gif" /> <a href="#limitexcept"><LimitExcept></a></li>
67 <li><img alt="" src="../images/down.gif" /> <a href="#limitinternalrecursion">LimitInternalRecursion</a></li>
68 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestbody">LimitRequestBody</a></li>
69 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfields">LimitRequestFields</a></li>
70 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfieldsize">LimitRequestFieldSize</a></li>
71 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestline">LimitRequestLine</a></li>
72 <li><img alt="" src="../images/down.gif" /> <a href="#limitxmlrequestbody">LimitXMLRequestBody</a></li>
73 <li><img alt="" src="../images/down.gif" /> <a href="#location"><Location></a></li>
74 <li><img alt="" src="../images/down.gif" /> <a href="#locationmatch"><LocationMatch></a></li>
75 <li><img alt="" src="../images/down.gif" /> <a href="#loglevel">LogLevel</a></li>
76 <li><img alt="" src="../images/down.gif" /> <a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></li>
77 <li><img alt="" src="../images/down.gif" /> <a href="#mutex">Mutex</a></li>
78 <li><img alt="" src="../images/down.gif" /> <a href="#namevirtualhost">NameVirtualHost</a></li>
79 <li><img alt="" src="../images/down.gif" /> <a href="#options">Options</a></li>
80 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitcpu">RLimitCPU</a></li>
81 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitmem">RLimitMEM</a></li>
82 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitnproc">RLimitNPROC</a></li>
83 <li><img alt="" src="../images/down.gif" /> <a href="#scriptinterpretersource">ScriptInterpreterSource</a></li>
84 <li><img alt="" src="../images/down.gif" /> <a href="#seerequesttail">SeeRequestTail</a></li>
85 <li><img alt="" src="../images/down.gif" /> <a href="#serveradmin">ServerAdmin</a></li>
86 <li><img alt="" src="../images/down.gif" /> <a href="#serveralias">ServerAlias</a></li>
87 <li><img alt="" src="../images/down.gif" /> <a href="#servername">ServerName</a></li>
88 <li><img alt="" src="../images/down.gif" /> <a href="#serverpath">ServerPath</a></li>
89 <li><img alt="" src="../images/down.gif" /> <a href="#serverroot">ServerRoot</a></li>
90 <li><img alt="" src="../images/down.gif" /> <a href="#serversignature">ServerSignature</a></li>
91 <li><img alt="" src="../images/down.gif" /> <a href="#servertokens">ServerTokens</a></li>
92 <li><img alt="" src="../images/down.gif" /> <a href="#sethandler">SetHandler</a></li>
93 <li><img alt="" src="../images/down.gif" /> <a href="#setinputfilter">SetInputFilter</a></li>
94 <li><img alt="" src="../images/down.gif" /> <a href="#setoutputfilter">SetOutputFilter</a></li>
95 <li><img alt="" src="../images/down.gif" /> <a href="#timeout">TimeOut</a></li>
96 <li><img alt="" src="../images/down.gif" /> <a href="#traceenable">TraceEnable</a></li>
97 <li><img alt="" src="../images/down.gif" /> <a href="#undefine">UnDefine</a></li>
98 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalname">UseCanonicalName</a></li>
99 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></li>
100 <li><img alt="" src="../images/down.gif" /> <a href="#virtualhost"><VirtualHost></a></li>
104 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
105 <div class="directive-section"><h2><a name="AcceptFilter" id="AcceptFilter">AcceptFilter</a> <a name="acceptfilter" id="acceptfilter">Directive</a></h2>
106 <table class="directive">
107 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures optimizations for a Protocol's Listener Sockets</td></tr>
108 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptFilter <var>protocol</var> <var>accept_filter</var></code></td></tr>
109 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
110 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
111 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
112 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.1.5 and later.
113 On Windows from Apache httpd 2.3.3 and later.</td></tr>
115 <p>This directive enables operating system specific optimizations for a
116 listening socket by the Protocol type. The basic premise is for the
117 kernel to not send a socket to the server process until either data
118 is received or an entire HTTP Request is buffered. Only
119 <a href="http://www.freebsd.org/cgi/man.cgi?query=accept_filter&sektion=9">
120 FreeBSD's Accept Filters</a>, Linux's more primitive
121 <code>TCP_DEFER_ACCEPT</code>, and Windows' optimized AcceptEx()
122 are currently supported.</p>
124 <p>Using <code>none</code> for an argument will disable any accept filters
125 for that protocol. This is useful for protocols that require a server
126 send data first, such as <code>ftp:</code> or <code>nntp</code>:</p>
127 <div class="example"><p><code>AcceptFilter nntp none</code></p></div>
129 <p>The default values on FreeBSD are:</p>
130 <div class="example"><p><code>
131 AcceptFilter http httpready <br />
132 AcceptFilter https dataready
135 <p>The <code>httpready</code> accept filter buffers entire HTTP requests at
136 the kernel level. Once an entire request is received, the kernel then
137 sends it to the server. See the
138 <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_http&sektion=9">
139 accf_http(9)</a> man page for more details. Since HTTPS requests are
140 encrypted only the <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_data&sektion=9">
141 accf_data(9)</a> filter is used.</p>
143 <p>The default values on Linux are:</p>
144 <div class="example"><p><code>
145 AcceptFilter http data <br />
146 AcceptFilter https data
149 <p>Linux's <code>TCP_DEFER_ACCEPT</code> does not support buffering http
150 requests. Any value besides <code>none</code> will enable
151 <code>TCP_DEFER_ACCEPT</code> on that listener. For more details
153 <a href="http://homepages.cwi.nl/~aeb/linux/man2html/man7/tcp.7.html">
154 tcp(7)</a> man page.</p>
156 <p>The default values on Windows are:</p>
157 <div class="example"><p><code>
158 AcceptFilter http data <br />
159 AcceptFilter https data
162 <p>Window's mpm_winnt interprets the AcceptFilter to toggle the AcceptEx()
163 API, and does not support http protocol buffering. There are two values
164 which utilize the Windows AcceptEx() API and will recycle network
165 sockets between connections. <code>data</code> waits until data has
166 been transmitted as documented above, and the initial data buffer and
167 network endpoint addresses are all retrieved from the single AcceptEx()
168 invocation. <code>connect</code> will use the AcceptEx() API, also
169 retrieve the network endpoint addresses, but like <code>none</code>
170 the <code>connect</code> option does not wait for the initial data
173 <p>On Windows, <code>none</code> uses accept() rather than than AcceptEx()
174 and will not recycle sockets between connections. This is useful for
175 network adapters with broken driver support, as well as some virtual
176 network providers such as vpn drivers, or spam, virus or spyware
181 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
182 <div class="directive-section"><h2><a name="AcceptPathInfo" id="AcceptPathInfo">AcceptPathInfo</a> <a name="acceptpathinfo" id="acceptpathinfo">Directive</a></h2>
183 <table class="directive">
184 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Resources accept trailing pathname information</td></tr>
185 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptPathInfo On|Off|Default</code></td></tr>
186 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AcceptPathInfo Default</code></td></tr>
187 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
188 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
189 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
190 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
191 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.0.30 and later</td></tr>
194 <p>This directive controls whether requests that contain trailing
195 pathname information that follows an actual filename (or
196 non-existent file in an existing directory) will be accepted or
197 rejected. The trailing pathname information can be made
198 available to scripts in the <code>PATH_INFO</code> environment
201 <p>For example, assume the location <code>/test/</code> points to
202 a directory that contains only the single file
203 <code>here.html</code>. Then requests for
204 <code>/test/here.html/more</code> and
205 <code>/test/nothere.html/more</code> both collect
206 <code>/more</code> as <code>PATH_INFO</code>.</p>
208 <p>The three possible arguments for the
209 <code class="directive">AcceptPathInfo</code> directive are:</p>
211 <dt><code>Off</code></dt><dd>A request will only be accepted if it
212 maps to a literal path that exists. Therefore a request with
213 trailing pathname information after the true filename such as
214 <code>/test/here.html/more</code> in the above example will return
215 a 404 NOT FOUND error.</dd>
217 <dt><code>On</code></dt><dd>A request will be accepted if a
218 leading path component maps to a file that exists. The above
219 example <code>/test/here.html/more</code> will be accepted if
220 <code>/test/here.html</code> maps to a valid file.</dd>
222 <dt><code>Default</code></dt><dd>The treatment of requests with
223 trailing pathname information is determined by the <a href="../handler.html">handler</a> responsible for the request.
224 The core handler for normal files defaults to rejecting
225 <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
226 <code>PATH_INFO</code> by default.</dd>
229 <p>The primary purpose of the <code>AcceptPathInfo</code>
230 directive is to allow you to override the handler's choice of
231 accepting or rejecting <code>PATH_INFO</code>. This override is required,
232 for example, when you use a <a href="../filter.html">filter</a>, such
233 as <a href="mod_include.html">INCLUDES</a>, to generate content
234 based on <code>PATH_INFO</code>. The core handler would usually reject
235 the request, so you can use the following configuration to enable
238 <div class="example"><p><code>
239 <Files "mypaths.shtml"><br />
240 <span class="indent">
241 Options +Includes<br />
242 SetOutputFilter INCLUDES<br />
243 AcceptPathInfo On<br />
250 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
251 <div class="directive-section"><h2><a name="AccessFileName" id="AccessFileName">AccessFileName</a> <a name="accessfilename" id="accessfilename">Directive</a></h2>
252 <table class="directive">
253 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Name of the distributed configuration file</td></tr>
254 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AccessFileName <var>filename</var> [<var>filename</var>] ...</code></td></tr>
255 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AccessFileName .htaccess</code></td></tr>
256 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
257 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
258 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
260 <p>While processing a request the server looks for
261 the first existing configuration file from this list of names in
262 every directory of the path to the document, if distributed
263 configuration files are <a href="#allowoverride">enabled for that
264 directory</a>. For example:</p>
266 <div class="example"><p><code>
270 <p>before returning the document
271 <code>/usr/local/web/index.html</code>, the server will read
272 <code>/.acl</code>, <code>/usr/.acl</code>,
273 <code>/usr/local/.acl</code> and <code>/usr/local/web/.acl</code>
274 for directives, unless they have been disabled with</p>
276 <div class="example"><p><code>
277 <Directory /><br />
278 <span class="indent">
279 AllowOverride None<br />
286 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
287 <li><a href="../configuring.html">Configuration Files</a></li>
288 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
291 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
292 <div class="directive-section"><h2><a name="AddDefaultCharset" id="AddDefaultCharset">AddDefaultCharset</a> <a name="adddefaultcharset" id="adddefaultcharset">Directive</a></h2>
293 <table class="directive">
294 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Default charset parameter to be added when a response
295 content-type is <code>text/plain</code> or <code>text/html</code></td></tr>
296 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AddDefaultCharset On|Off|<var>charset</var></code></td></tr>
297 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AddDefaultCharset Off</code></td></tr>
298 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
299 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
300 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
301 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
303 <p>This directive specifies a default value for the media type
304 charset parameter (the name of a character encoding) to be added
305 to a response if and only if the response's content-type is either
306 <code>text/plain</code> or <code>text/html</code>. This should override
307 any charset specified in the body of the response via a <code>META</code>
308 element, though the exact behavior is often dependent on the user's client
309 configuration. A setting of <code>AddDefaultCharset Off</code>
310 disables this functionality. <code>AddDefaultCharset On</code> enables
311 a default charset of <code>iso-8859-1</code>. Any other value is assumed
312 to be the <var>charset</var> to be used, which should be one of the
313 <a href="http://www.iana.org/assignments/character-sets">IANA registered
314 charset values</a> for use in Internet media types (MIME types).
317 <div class="example"><p><code>
318 AddDefaultCharset utf-8
321 <p><code class="directive">AddDefaultCharset</code> should only be used when all
322 of the text resources to which it applies are known to be in that
323 character encoding and it is too inconvenient to label their charset
324 individually. One such example is to add the charset parameter
325 to resources containing generated content, such as legacy CGI
326 scripts, that might be vulnerable to cross-site scripting attacks
327 due to user-provided data being included in the output. Note, however,
328 that a better solution is to just fix (or delete) those scripts, since
329 setting a default charset does not protect users that have enabled
330 the "auto-detect character encoding" feature on their browser.</p>
334 <li><code class="directive"><a href="../mod/mod_mime.html#addcharset">AddCharset</a></code></li>
337 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
338 <div class="directive-section"><h2><a name="AllowEncodedSlashes" id="AllowEncodedSlashes">AllowEncodedSlashes</a> <a name="allowencodedslashes" id="allowencodedslashes">Directive</a></h2>
339 <table class="directive">
340 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether encoded path separators in URLs are allowed to
341 be passed through</td></tr>
342 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowEncodedSlashes On|Off</code></td></tr>
343 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowEncodedSlashes Off</code></td></tr>
344 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
345 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
346 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
347 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.0.46 and later</td></tr>
349 <p>The <code class="directive">AllowEncodedSlashes</code> directive allows URLs
350 which contain encoded path separators (<code>%2F</code> for <code>/</code>
351 and additionally <code>%5C</code> for <code>\</code> on according systems)
352 to be used. Normally such URLs are refused with a 404 (Not found) error.</p>
354 <p>Turning <code class="directive">AllowEncodedSlashes</code> <code>On</code> is
355 mostly useful when used in conjunction with <code>PATH_INFO</code>.</p>
357 <div class="note"><h3>Note</h3>
358 <p>Allowing encoded slashes does <em>not</em> imply <em>decoding</em>.
359 Occurrences of <code>%2F</code> or <code>%5C</code> (<em>only</em> on
360 according systems) will be left as such in the otherwise decoded URL
366 <li><code class="directive"><a href="#acceptpathinfo">AcceptPathInfo</a></code></li>
369 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
370 <div class="directive-section"><h2><a name="AllowOverride" id="AllowOverride">AllowOverride</a> <a name="allowoverride" id="allowoverride">Directive</a></h2>
371 <table class="directive">
372 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Types of directives that are allowed in
373 <code>.htaccess</code> files</td></tr>
374 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverride All|None|<var>directive-type</var>
375 [<var>directive-type</var>] ...</code></td></tr>
376 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowOverride All</code></td></tr>
377 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
378 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
379 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
381 <p>When the server finds an <code>.htaccess</code> file (as
382 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>)
383 it needs to know which directives declared in that file can override
384 earlier configuration directives.</p>
386 <div class="note"><h3>Only available in <Directory> sections</h3>
387 <code class="directive">AllowOverride</code> is valid only in
388 <code class="directive"><a href="#directory"><Directory></a></code>
389 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
390 <code class="directive"><a href="#files"><Files></a></code> sections.
393 <p>When this directive is set to <code>None</code>, then
394 <a href="#accessfilename">.htaccess</a> files are completely ignored.
395 In this case, the server will not even attempt to read
396 <code>.htaccess</code> files in the filesystem.</p>
398 <p>When this directive is set to <code>All</code>, then any
399 directive which has the .htaccess <a href="directive-dict.html#Context">Context</a> is allowed in
400 <code>.htaccess</code> files.</p>
402 <p>The <var>directive-type</var> can be one of the following
403 groupings of directives.</p>
410 Allow use of the authorization directives (<code class="directive"><a href="../mod/mod_authn_dbm.html#authdbmgroupfile">AuthDBMGroupFile</a></code>,
411 <code class="directive"><a href="../mod/mod_authn_dbm.html#authdbmuserfile">AuthDBMUserFile</a></code>,
412 <code class="directive"><a href="../mod/mod_authz_groupfile.html#authgroupfile">AuthGroupFile</a></code>,
413 <code class="directive"><a href="../mod/mod_authn_core.html#authname">AuthName</a></code>,
414 <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>
419 Allow use of the directives controlling document types
420 (<code class="directive"><a href="#errordocument">ErrorDocument</a></code>,
421 <code class="directive"><a href="#forcetype">ForceType</a></code>,
422 <code class="directive"><a href="../mod/mod_negotiation.html#languagepriority">LanguagePriority</a></code>,
423 <code class="directive"><a href="#sethandler">SetHandler</a></code>,
424 <code class="directive"><a href="#setinputfilter">SetInputFilter</a></code>,
425 <code class="directive"><a href="#setoutputfilter">SetOutputFilter</a></code>, and
426 <code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code> Add* and Remove* directives),
427 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>),
428 <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>) and
429 <code class="directive"><a href="../mod/mod_actions.html#action">Action</a></code> from
430 <code class="module"><a href="../mod/mod_actions.html">mod_actions</a></code>.
436 Allow use of the directives controlling directory indexing
437 (<code class="directive"><a href="../mod/mod_autoindex.html#adddescription">AddDescription</a></code>,
438 <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>,
439 <code class="directive"><a href="../mod/mod_autoindex.html#addiconbytype">AddIconByType</a></code>,
440 <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_autoindex.html#fancyindexing">FancyIndexing</a></code>, <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>,
446 Allow use of the directives controlling host access (<code class="directive"><a href="../mod/mod_authz_host.html#allow">Allow</a></code>, <code class="directive"><a href="../mod/mod_authz_host.html#deny">Deny</a></code> and <code class="directive"><a href="../mod/mod_authz_host.html#order">Order</a></code>).</dd>
448 <dt>Options[=<var>Option</var>,...]</dt>
451 Allow use of the directives controlling specific directory
452 features (<code class="directive"><a href="#options">Options</a></code> and
453 <code class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></code>).
454 An equal sign may be given followed by a comma (but no spaces)
455 separated lists of options that may be set using the <code class="directive"><a href="#options">Options</a></code> command.</dd>
460 <div class="example"><p><code>
461 AllowOverride AuthConfig Indexes
464 <p>In the example above all directives that are neither in the group
465 <code>AuthConfig</code> nor <code>Indexes</code> cause an internal
468 <div class="note"><p>For security and performance reasons, do not set
469 <code>AllowOverride</code> to anything other than <code>None</code>
470 in your <code><Directory /></code> block. Instead, find (or
471 create) the <code><Directory></code> block that refers to the
472 directory where you're actually planning to place a
473 <code>.htaccess</code> file.</p>
478 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
479 <li><a href="../configuring.html">Configuration Files</a></li>
480 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
483 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
484 <div class="directive-section"><h2><a name="CGIMapExtension" id="CGIMapExtension">CGIMapExtension</a> <a name="cgimapextension" id="cgimapextension">Directive</a></h2>
485 <table class="directive">
486 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
488 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIMapExtension <var>cgi-path</var> <var>.extension</var></code></td></tr>
489 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
490 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
491 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
492 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
493 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>NetWare only</td></tr>
495 <p>This directive is used to control how Apache httpd finds the
496 interpreter used to run CGI scripts. For example, setting
497 <code>CGIMapExtension sys:\foo.nlm .foo</code> will
498 cause all CGI script files with a <code>.foo</code> extension to
499 be passed to the FOO interpreter.</p>
502 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
503 <div class="directive-section"><h2><a name="ContentDigest" id="ContentDigest">ContentDigest</a> <a name="contentdigest" id="contentdigest">Directive</a></h2>
504 <table class="directive">
505 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables the generation of <code>Content-MD5</code> HTTP Response
507 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ContentDigest On|Off</code></td></tr>
508 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ContentDigest Off</code></td></tr>
509 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
510 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
511 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
512 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
514 <p>This directive enables the generation of
515 <code>Content-MD5</code> headers as defined in RFC1864
516 respectively RFC2616.</p>
518 <p>MD5 is an algorithm for computing a "message digest"
519 (sometimes called "fingerprint") of arbitrary-length data, with
520 a high degree of confidence that any alterations in the data
521 will be reflected in alterations in the message digest.</p>
523 <p>The <code>Content-MD5</code> header provides an end-to-end
524 message integrity check (MIC) of the entity-body. A proxy or
525 client may check this header for detecting accidental
526 modification of the entity-body in transit. Example header:</p>
528 <div class="example"><p><code>
529 Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
532 <p>Note that this can cause performance problems on your server
533 since the message digest is computed on every request (the
534 values are not cached).</p>
536 <p><code>Content-MD5</code> is only sent for documents served
537 by the <code class="module"><a href="../mod/core.html">core</a></code>, and not by any module. For example,
538 SSI documents, output from CGI scripts, and byte range responses
539 do not have this header.</p>
542 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
543 <div class="directive-section"><h2><a name="DefaultType" id="DefaultType">DefaultType</a> <a name="defaulttype" id="defaulttype">Directive</a></h2>
544 <table class="directive">
545 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>This directive has no effect other than to emit warnings
546 if the value is not <code>none</code>. In prior versions, DefaultType
547 would specify a default media type to assign to response content for
548 which no other media type configuration could be found.
550 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultType <var>media-type|none</var></code></td></tr>
551 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultType none</code></td></tr>
552 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
553 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
554 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
555 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
556 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The argument <code>none</code> is available in Apache httpd 2.2.7 and later. All other choices are DISABLED for 2.3.x and later.</td></tr>
558 <p>This directive has been disabled. For backwards compatibility
559 of configuration files, it may be specified with the value
560 <code>none</code>, meaning no default media type. For example:</p>
562 <div class="example"><p><code>
566 <p><code>DefaultType None</code> is only available in
567 httpd-2.2.7 and later.</p>
569 <p>Use the mime.types configuration file and the
570 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code> to configure media
571 type assignments via file extensions, or the
572 <code class="directive"><a href="#forcetype">ForceType</a></code> directive to configure
573 the media type for specific resources. Otherwise, the server will
574 send the response without a Content-Type header field and the
575 recipient may attempt to guess the media type.</p>
578 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
579 <div class="directive-section"><h2><a name="Define" id="Define">Define</a> <a name="define" id="define">Directive</a></h2>
580 <table class="directive">
581 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Define the existence of a variable</td></tr>
582 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Define <var>parameter-name</var></code></td></tr>
583 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
584 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
585 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
587 <p>Equivalent to passing the <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</p>
588 <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
589 <code>-D</code> arguments in any startup scripts.</p>
592 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
593 <div class="directive-section"><h2><a name="Directory" id="Directory"><Directory></a> <a name="directory" id="directory">Directive</a></h2>
594 <table class="directive">
595 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose a group of directives that apply only to the
596 named file-system directory and sub-directories</td></tr>
597 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Directory <var>directory-path</var>>
598 ... </Directory></code></td></tr>
599 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
600 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
601 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
603 <p><code class="directive"><Directory></code> and
604 <code></Directory></code> are used to enclose a group of
605 directives that will apply only to the named directory and
606 sub-directories of that directory. Any directive that is allowed
607 in a directory context may be used. <var>Directory-path</var> is
608 either the full path to a directory, or a wild-card string using
609 Unix shell-style matching. In a wild-card string, <code>?</code> matches
610 any single character, and <code>*</code> matches any sequences of
611 characters. You may also use <code>[]</code> character ranges. None
612 of the wildcards match a `/' character, so <code><Directory
613 /*/public_html></code> will not match
614 <code>/home/user/public_html</code>, but <code><Directory
615 /home/*/public_html></code> will match. Example:</p>
617 <div class="example"><p><code>
618 <Directory /usr/local/httpd/htdocs><br />
619 <span class="indent">
620 Options Indexes FollowSymLinks<br />
626 <p>Be careful with the <var>directory-path</var> arguments:
627 They have to literally match the filesystem path which Apache httpd uses
628 to access the files. Directives applied to a particular
629 <code><Directory></code> will not apply to files accessed from
630 that same directory via a different path, such as via different symbolic
634 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular
635 expressions</a> can also be used, with the addition of the
636 <code>~</code> character. For example:</p>
638 <div class="example"><p><code>
639 <Directory ~ "^/www/.*/[0-9]{3}">
642 <p>would match directories in <code>/www/</code> that consisted of
645 <p>If multiple (non-regular expression) <code class="directive"><Directory></code> sections
646 match the directory (or one of its parents) containing a document,
647 then the directives are applied in the order of shortest match
648 first, interspersed with the directives from the <a href="#accessfilename">.htaccess</a> files. For example,
651 <div class="example"><p><code>
652 <Directory /><br />
653 <span class="indent">
654 AllowOverride None<br />
656 </Directory><br />
658 <Directory /home/><br />
659 <span class="indent">
660 AllowOverride FileInfo<br />
665 <p>for access to the document <code>/home/web/dir/doc.html</code>
669 <li>Apply directive <code>AllowOverride None</code>
670 (disabling <code>.htaccess</code> files).</li>
672 <li>Apply directive <code>AllowOverride FileInfo</code> (for
673 directory <code>/home</code>).</li>
675 <li>Apply any <code>FileInfo</code> directives in
676 <code>/home/.htaccess</code>, <code>/home/web/.htaccess</code> and
677 <code>/home/web/dir/.htaccess</code> in that order.</li>
680 <p>Regular expressions are not considered until after all of the
681 normal sections have been applied. Then all of the regular
682 expressions are tested in the order they appeared in the
683 configuration file. For example, with</p>
685 <div class="example"><p><code>
686 <Directory ~ abc$><br />
687 <span class="indent">
688 # ... directives here ...<br />
693 <p>the regular expression section won't be considered until after
694 all normal <code class="directive"><Directory></code>s and
695 <code>.htaccess</code> files have been applied. Then the regular
696 expression will match on <code>/home/abc/public_html/abc</code> and
697 the corresponding <code class="directive"><Directory></code> will
700 <p><strong>Note that the default access for
701 <code><Directory /></code> is <code>Allow from All</code>.
702 This means that Apache httpd will serve any file mapped from an URL. It is
703 recommended that you change this with a block such
706 <div class="example"><p><code>
707 <Directory /><br />
708 <span class="indent">
709 Order Deny,Allow<br />
715 <p><strong>and then override this for directories you
716 <em>want</em> accessible. See the <a href="../misc/security_tips.html">Security Tips</a> page for more
717 details.</strong></p>
719 <p>The directory sections occur in the <code>httpd.conf</code> file.
720 <code class="directive"><Directory></code> directives
721 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>
725 <li><a href="../sections.html">How <Directory>,
726 <Location> and <Files> sections work</a> for an
727 explanation of how these different sections are combined when a
728 request is received</li>
731 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
732 <div class="directive-section"><h2><a name="DirectoryMatch" id="DirectoryMatch"><DirectoryMatch></a> <a name="directorymatch" id="directorymatch">Directive</a></h2>
733 <table class="directive">
734 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose directives that apply to
735 file-system directories matching a regular expression and their
736 subdirectories</td></tr>
737 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><DirectoryMatch <var>regex</var>>
738 ... </DirectoryMatch></code></td></tr>
739 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
740 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
741 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
743 <p><code class="directive"><DirectoryMatch></code> and
744 <code></DirectoryMatch></code> are used to enclose a group
745 of directives which will apply only to the named directory and
746 sub-directories of that directory, the same as <code class="directive"><a href="#directory"><Directory></a></code>. However, it
747 takes as an argument a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular
748 expression</a>. For example:</p>
750 <div class="example"><p><code>
751 <DirectoryMatch "^/www/(.+/)?[0-9]{3}">
754 <p>would match directories in <code>/www/</code> that consisted of three
759 <li><code class="directive"><a href="#directory"><Directory></a></code> for
760 a description of how regular expressions are mixed in with normal
761 <code class="directive"><Directory></code>s</li>
762 <li><a href="../sections.html">How <Directory>, <Location> and
763 <Files> sections work</a> for an explanation of how these different
764 sections are combined when a request is received</li>
767 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
768 <div class="directive-section"><h2><a name="DocumentRoot" id="DocumentRoot">DocumentRoot</a> <a name="documentroot" id="documentroot">Directive</a></h2>
769 <table class="directive">
770 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory that forms the main document tree visible
771 from the web</td></tr>
772 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DocumentRoot <var>directory-path</var></code></td></tr>
773 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DocumentRoot /usr/local/apache/htdocs</code></td></tr>
774 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
775 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
776 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
778 <p>This directive sets the directory from which <code class="program"><a href="../programs/httpd.html">httpd</a></code>
779 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
780 path from the requested URL to the document root to make the
781 path to the document. Example:</p>
783 <div class="example"><p><code>
784 DocumentRoot /usr/web
788 <code>http://www.my.host.com/index.html</code> refers to
789 <code>/usr/web/index.html</code>. If the <var>directory-path</var> is
790 not absolute then it is assumed to be relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
792 <p>The <code class="directive">DocumentRoot</code> should be specified without
793 a trailing slash.</p>
797 <li><a href="../urlmapping.html#documentroot">Mapping URLs to Filesystem
801 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
802 <div class="directive-section"><h2><a name="EnableMMAP" id="EnableMMAP">EnableMMAP</a> <a name="enablemmap" id="enablemmap">Directive</a></h2>
803 <table class="directive">
804 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use memory-mapping to read files during delivery</td></tr>
805 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableMMAP On|Off</code></td></tr>
806 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableMMAP On</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>
812 <p>This directive controls whether the <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use
813 memory-mapping if it needs to read the contents of a file during
814 delivery. By default, when the handling of a request requires
815 access to the data within a file -- for example, when delivering a
816 server-parsed file using <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> -- Apache httpd
817 memory-maps the file if the OS supports it.</p>
819 <p>This memory-mapping sometimes yields a performance improvement.
820 But in some environments, it is better to disable the memory-mapping
821 to prevent operational problems:</p>
824 <li>On some multiprocessor systems, memory-mapping can reduce the
825 performance of the <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</li>
826 <li>Deleting or truncating a file while <code class="program"><a href="../programs/httpd.html">httpd</a></code>
827 has it memory-mapped can cause <code class="program"><a href="../programs/httpd.html">httpd</a></code> to
828 crash with a segmentation fault.
832 <p>For server configurations that are vulnerable to these problems,
833 you should disable memory-mapping of delivered files by specifying:</p>
835 <div class="example"><p><code>
839 <p>For NFS mounted files, this feature may be disabled explicitly for
840 the offending files by specifying:</p>
842 <div class="example"><p><code>
843 <Directory "/path-to-nfs-files">
844 <span class="indent">
851 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
852 <div class="directive-section"><h2><a name="EnableSendfile" id="EnableSendfile">EnableSendfile</a> <a name="enablesendfile" id="enablesendfile">Directive</a></h2>
853 <table class="directive">
854 <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>
855 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableSendfile On|Off</code></td></tr>
856 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableSendfile On</code></td></tr>
857 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
858 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
859 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
860 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
861 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.0.44 and later</td></tr>
863 <p>This directive controls whether <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use the
864 sendfile support from the kernel to transmit file contents to the client.
865 By default, when the handling of a request requires no access
866 to the data within a file -- for example, when delivering a
867 static file -- Apache httpd uses sendfile to deliver the file contents
868 without ever reading the file if the OS supports it.</p>
870 <p>This sendfile mechanism avoids separate read and send operations,
871 and buffer allocations. But on some platforms or within some
872 filesystems, it is better to disable this feature to avoid
873 operational problems:</p>
876 <li>Some platforms may have broken sendfile support that the build
877 system did not detect, especially if the binaries were built on
878 another box and moved to such a machine with broken sendfile
880 <li>On Linux the use of sendfile triggers TCP-checksum
881 offloading bugs on certain networking cards when using IPv6.</li>
882 <li>On Linux on Itanium, sendfile may be unable to handle files
883 over 2GB in size.</li>
884 <li>With a network-mounted <code class="directive"><a href="#documentroot">DocumentRoot</a></code> (e.g., NFS or SMB),
885 the kernel may be unable to serve the network file through
889 <p>For server configurations that are vulnerable to these problems,
890 you should disable this feature by specifying:</p>
892 <div class="example"><p><code>
896 <p>For NFS or SMB mounted files, this feature may be disabled explicitly
897 for the offending files by specifying:</p>
899 <div class="example"><p><code>
900 <Directory "/path-to-nfs-files">
901 <span class="indent">
906 <p>Please note that the per-directory and .htaccess configuration
907 of <code class="directive">EnableSendfile</code> is not supported by
908 <code class="module"><a href="../mod/mod_disk_cache.html">mod_disk_cache</a></code>.
909 Only global definition of <code class="directive">EnableSendfile</code>
910 is taken into account by the module.
914 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
915 <div class="directive-section"><h2><a name="ErrorDocument" id="ErrorDocument">ErrorDocument</a> <a name="errordocument" id="errordocument">Directive</a></h2>
916 <table class="directive">
917 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>What the server will return to the client
918 in case of an error</td></tr>
919 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ErrorDocument <var>error-code</var> <var>document</var></code></td></tr>
920 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
921 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
922 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
923 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
924 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Quoting syntax for text messages is different in Apache HTTP Server
927 <p>In the event of a problem or error, Apache httpd can be configured
928 to do one of four things,</p>
931 <li>output a simple hardcoded error message</li>
933 <li>output a customized message</li>
935 <li>redirect to a local <var>URL-path</var> to handle the
938 <li>redirect to an external <var>URL</var> to handle the
942 <p>The first option is the default, while options 2-4 are
943 configured using the <code class="directive">ErrorDocument</code>
944 directive, which is followed by the HTTP response code and a URL
945 or a message. Apache httpd will sometimes offer additional information
946 regarding the problem/error.</p>
948 <p>URLs can begin with a slash (/) for local web-paths (relative
949 to the <code class="directive"><a href="#documentroot">DocumentRoot</a></code>), or be a
950 full URL which the client can resolve. Alternatively, a message
951 can be provided to be displayed by the browser. Examples:</p>
953 <div class="example"><p><code>
954 ErrorDocument 500 http://foo.example.com/cgi-bin/tester<br />
955 ErrorDocument 404 /cgi-bin/bad_urls.pl<br />
956 ErrorDocument 401 /subscription_info.html<br />
957 ErrorDocument 403 "Sorry can't allow you access today"
960 <p>Additionally, the special value <code>default</code> can be used
961 to specify Apache httpd's simple hardcoded message. While not required
962 under normal circumstances, <code>default</code> will restore
963 Apache httpd's simple hardcoded message for configurations that would
964 otherwise inherit an existing <code class="directive">ErrorDocument</code>.</p>
966 <div class="example"><p><code>
967 ErrorDocument 404 /cgi-bin/bad_urls.pl<br /><br />
968 <Directory /web/docs><br />
969 <span class="indent">
970 ErrorDocument 404 default<br />
975 <p>Note that when you specify an <code class="directive">ErrorDocument</code>
976 that points to a remote URL (ie. anything with a method such as
977 <code>http</code> in front of it), Apache HTTP Server will send a redirect to the
978 client to tell it where to find the document, even if the
979 document ends up being on the same server. This has several
980 implications, the most important being that the client will not
981 receive the original error status code, but instead will
982 receive a redirect status code. This in turn can confuse web
983 robots and other clients which try to determine if a URL is
984 valid using the status code. In addition, if you use a remote
985 URL in an <code>ErrorDocument 401</code>, the client will not
986 know to prompt the user for a password since it will not
987 receive the 401 status code. Therefore, <strong>if you use an
988 <code>ErrorDocument 401</code> directive then it must refer to a local
989 document.</strong></p>
991 <p>Microsoft Internet Explorer (MSIE) will by default ignore
992 server-generated error messages when they are "too small" and substitute
993 its own "friendly" error messages. The size threshold varies depending on
994 the type of error, but in general, if you make your error document
995 greater than 512 bytes, then MSIE will show the server-generated
996 error rather than masking it. More information is available in
997 Microsoft Knowledge Base article <a href="http://support.microsoft.com/default.aspx?scid=kb;en-us;Q294807">Q294807</a>.</p>
999 <p>Although most error messages can be overriden, there are certain
1000 circumstances where the internal messages are used regardless of the
1001 setting of <code class="directive"><a href="#errordocument">ErrorDocument</a></code>. In
1002 particular, if a malformed request is detected, normal request processing
1003 will be immediately halted and the internal error message returned.
1004 This is necessary to guard against security problems caused by
1007 <p>If you are using mod_proxy, you may wish to enable
1008 <code class="directive"><a href="../mod/mod_proxy.html#proxyerroroverride">ProxyErrorOverride</a></code> so that you can provide
1009 custom error messages on behalf of your Origin servers. If you don't enable ProxyErrorOverride,
1010 Apache httpd will not generate custom error documents for proxied content.</p>
1014 <li><a href="../custom-error.html">documentation of
1015 customizable responses</a></li>
1018 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1019 <div class="directive-section"><h2><a name="ErrorLog" id="ErrorLog">ErrorLog</a> <a name="errorlog" id="errorlog">Directive</a></h2>
1020 <table class="directive">
1021 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Location where the server will log errors</td></tr>
1022 <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>
1023 <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>
1024 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1025 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1026 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1028 <p>The <code class="directive">ErrorLog</code> directive sets the name of
1029 the file to which the server will log any errors it encounters. If
1030 the <var>file-path</var> is not absolute then it is assumed to be
1031 relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1033 <div class="example"><h3>Example</h3><p><code>
1034 ErrorLog /var/log/httpd/error_log
1037 <p>If the <var>file-path</var>
1038 begins with a pipe (|) then it is assumed to be a command to spawn
1039 to handle the error log.</p>
1041 <div class="example"><h3>Example</h3><p><code>
1042 ErrorLog "|/usr/local/bin/httpd_errors"
1045 <p>Using <code>syslog</code> instead of a filename enables logging
1046 via syslogd(8) if the system supports it. The default is to use
1047 syslog facility <code>local7</code>, but you can override this by
1048 using the <code>syslog:<var>facility</var></code> syntax where
1049 <var>facility</var> can be one of the names usually documented in
1052 <div class="example"><h3>Example</h3><p><code>
1053 ErrorLog syslog:user
1056 <p>SECURITY: See the <a href="../misc/security_tips.html#serverroot">security tips</a>
1057 document for details on why your security could be compromised
1058 if the directory where log files are stored is writable by
1059 anyone other than the user that starts the server.</p>
1060 <div class="warning"><h3>Note</h3>
1061 <p>When entering a file path on non-Unix platforms, care should be taken
1062 to make sure that only forward slashed are used even though the platform
1063 may allow the use of back slashes. In general it is a good idea to always
1064 use forward slashes throughout the configuration files.</p>
1069 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1070 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1073 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1074 <div class="directive-section"><h2><a name="ExtendedStatus" id="ExtendedStatus">ExtendedStatus</a> <a name="extendedstatus" id="extendedstatus">Directive</a></h2>
1075 <table class="directive">
1076 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Keep track of extended status information for each
1078 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ExtendedStatus On|Off</code></td></tr>
1079 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ExtendedStatus Off[*]</code></td></tr>
1080 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
1081 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1082 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1084 <p>This option tracks additional data per worker about the
1085 currently executing request, and a utilization summary; you
1086 can see these variables during runtime by configuring
1087 <code class="module"><a href="../mod/mod_status.html">mod_status</a></code>. Note that other modules may
1088 rely on this scoreboard.</p>
1090 <p>This setting applies to the entire server, and cannot be
1091 enabled or disabled on a virtualhost-by-virtualhost basis.
1092 The collection of extended status information can slow down
1093 the server. Also note that this setting cannot be changed
1094 during a graceful restart.</p>
1097 <p>Note that loading <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> will change
1098 the default behavior to ExtendedStatus On, while other
1099 third party modules may do the same. Such modules rely on
1100 collecting detailed information about the state of all workers.
1101 The default is changed by <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> beginning
1102 with version 2.3.6; the previous default was always Off.</p>
1107 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1108 <div class="directive-section"><h2><a name="FileETag" id="FileETag">FileETag</a> <a name="fileetag" id="fileetag">Directive</a></h2>
1109 <table class="directive">
1110 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>File attributes used to create the ETag
1111 HTTP response header for static files</td></tr>
1112 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>FileETag <var>component</var> ...</code></td></tr>
1113 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>FileETag INode MTime Size</code></td></tr>
1114 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1115 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1116 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1117 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1120 The <code class="directive">FileETag</code> directive configures the file
1121 attributes that are used to create the <code>ETag</code> (entity
1122 tag) response header field when the document is based on a static file.
1123 (The <code>ETag</code> value is used in cache management to save
1124 network bandwidth.) The
1125 <code class="directive">FileETag</code> directive allows you to choose
1126 which of these -- if any -- should be used. The recognized keywords are:
1130 <dt><strong>INode</strong></dt>
1131 <dd>The file's i-node number will be included in the calculation</dd>
1132 <dt><strong>MTime</strong></dt>
1133 <dd>The date and time the file was last modified will be included</dd>
1134 <dt><strong>Size</strong></dt>
1135 <dd>The number of bytes in the file will be included</dd>
1136 <dt><strong>All</strong></dt>
1137 <dd>All available fields will be used. This is equivalent to:
1138 <div class="example"><p><code>FileETag INode MTime Size</code></p></div></dd>
1139 <dt><strong>None</strong></dt>
1140 <dd>If a document is file-based, no <code>ETag</code> field will be
1141 included in the response</dd>
1144 <p>The <code>INode</code>, <code>MTime</code>, and <code>Size</code>
1145 keywords may be prefixed with either <code>+</code> or <code>-</code>,
1146 which allow changes to be made to the default setting inherited
1147 from a broader scope. Any keyword appearing without such a prefix
1148 immediately and completely cancels the inherited setting.</p>
1150 <p>If a directory's configuration includes
1151 <code>FileETag INode MTime Size</code>, and a
1152 subdirectory's includes <code>FileETag -INode</code>,
1153 the setting for that subdirectory (which will be inherited by
1154 any sub-subdirectories that don't override it) will be equivalent to
1155 <code>FileETag MTime Size</code>.</p>
1156 <div class="warning"><h3>Warning</h3>
1157 Do not change the default for directories or locations that have WebDAV
1158 enabled and use <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> as a storage provider.
1159 <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> uses <code>INode MTime Size</code>
1160 as a fixed format for <code>ETag</code> comparisons on conditional requests.
1161 These conditional requests will break if the <code>ETag</code> format is
1162 changed via <code class="directive">FileETag</code>.
1164 <div class="note"><h3>Server Side Includes</h3>
1165 An ETag is not generated for responses parsed by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>,
1166 since the response entity can change without a change of the INode, MTime, or Size
1167 of the static file with embedded SSI directives.
1172 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1173 <div class="directive-section"><h2><a name="Files" id="Files"><Files></a> <a name="files" id="files">Directive</a></h2>
1174 <table class="directive">
1175 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to matched
1177 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Files <var>filename</var>> ... </Files></code></td></tr>
1178 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1179 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1180 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1181 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1183 <p>The <code class="directive"><Files></code> directive
1184 limits the scope of the enclosed directives by filename. It is comparable
1185 to the <code class="directive"><a href="#directory"><Directory></a></code>
1186 and <code class="directive"><a href="#location"><Location></a></code>
1187 directives. It should be matched with a <code></Files></code>
1188 directive. The directives given within this section will be applied to
1189 any object with a basename (last component of filename) matching the
1190 specified filename. <code class="directive"><Files></code>
1191 sections are processed in the order they appear in the
1192 configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
1193 <code>.htaccess</code> files are read, but before <code class="directive"><a href="#location"><Location></a></code> sections. Note
1194 that <code class="directive"><Files></code> can be nested
1195 inside <code class="directive"><a href="#directory"><Directory></a></code> sections to restrict the
1196 portion of the filesystem they apply to.</p>
1198 <p>The <var>filename</var> argument should include a filename, or
1199 a wild-card string, where <code>?</code> matches any single character,
1200 and <code>*</code> matches any sequences of characters.
1201 <a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
1202 can also be used, with the addition of the
1203 <code>~</code> character. For example:</p>
1205 <div class="example"><p><code>
1206 <Files ~ "\.(gif|jpe?g|png)$">
1209 <p>would match most common Internet graphics formats. <code class="directive"><a href="#filesmatch"><FilesMatch></a></code> is preferred,
1212 <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
1213 <code>.htaccess</code> files. This allows users to control access to
1214 their own files, at a file-by-file level.</p>
1219 <li><a href="../sections.html">How <Directory>, <Location>
1220 and <Files> sections work</a> for an explanation of how these
1221 different sections are combined when a request is received</li>
1224 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1225 <div class="directive-section"><h2><a name="FilesMatch" id="FilesMatch"><FilesMatch></a> <a name="filesmatch" id="filesmatch">Directive</a></h2>
1226 <table class="directive">
1227 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to regular-expression matched
1229 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><FilesMatch <var>regex</var>> ... </FilesMatch></code></td></tr>
1230 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1231 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1232 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1233 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1235 <p>The <code class="directive"><FilesMatch></code> directive
1236 limits the scope of the enclosed directives by filename, just as the
1237 <code class="directive"><a href="#files"><Files></a></code> directive
1238 does. However, it accepts a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular
1239 expression</a>. For example:</p>
1241 <div class="example"><p><code>
1242 <FilesMatch "\.(gif|jpe?g|png)$">
1245 <p>would match most common Internet graphics formats.</p>
1249 <li><a href="../sections.html">How <Directory>, <Location>
1250 and <Files> sections work</a> for an explanation of how these
1251 different sections are combined when a request is received</li>
1254 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1255 <div class="directive-section"><h2><a name="ForceType" id="ForceType">ForceType</a> <a name="forcetype" id="forcetype">Directive</a></h2>
1256 <table class="directive">
1257 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be served with the specified
1258 media type in the HTTP Content-Type header field</td></tr>
1259 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ForceType <var>media-type</var>|None</code></td></tr>
1260 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
1261 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1262 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1263 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1264 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Moved to the core in Apache httpd 2.0</td></tr>
1266 <p>When placed into an <code>.htaccess</code> file or a
1267 <code class="directive"><a href="#directory"><Directory></a></code>, or
1268 <code class="directive"><a href="#location"><Location></a></code> or
1269 <code class="directive"><a href="#files"><Files></a></code>
1270 section, this directive forces all matching files to be served
1271 with the content type identification given by
1272 <var>media-type</var>. For example, if you had a directory full of
1273 GIF files, but did not want to label them all with <code>.gif</code>,
1274 you might want to use:</p>
1276 <div class="example"><p><code>
1280 <p>Note that this directive overrides other indirect media type
1281 associations defined in mime.types or via the
1282 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code>.</p>
1284 <p>You can also override more general
1285 <code class="directive">ForceType</code> settings
1286 by using the value of <code>None</code>:</p>
1288 <div class="example"><p><code>
1289 # force all files to be image/gif:<br />
1290 <Location /images><br />
1291 <span class="indent">
1292 ForceType image/gif<br />
1294 </Location><br />
1296 # but normal mime-type associations here:<br />
1297 <Location /images/mixed><br />
1298 <span class="indent">
1299 ForceType None<br />
1305 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1306 <div class="directive-section"><h2><a name="HostnameLookups" id="HostnameLookups">HostnameLookups</a> <a name="hostnamelookups" id="hostnamelookups">Directive</a></h2>
1307 <table class="directive">
1308 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables DNS lookups on client IP addresses</td></tr>
1309 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HostnameLookups On|Off|Double</code></td></tr>
1310 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HostnameLookups Off</code></td></tr>
1311 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1312 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1313 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1315 <p>This directive enables DNS lookups so that host names can be
1316 logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
1317 The value <code>Double</code> refers to doing double-reverse
1318 DNS lookup. That is, after a reverse lookup is performed, a forward
1319 lookup is then performed on that result. At least one of the IP
1320 addresses in the forward lookup must match the original
1321 address. (In "tcpwrappers" terminology this is called
1322 <code>PARANOID</code>.)</p>
1324 <p>Regardless of the setting, when <code class="module"><a href="../mod/mod_authz_host.html">mod_authz_host</a></code> is
1325 used for controlling access by hostname, a double reverse lookup
1326 will be performed. This is necessary for security. Note that the
1327 result of this double-reverse isn't generally available unless you
1328 set <code>HostnameLookups Double</code>. For example, if only
1329 <code>HostnameLookups On</code> and a request is made to an object
1330 that is protected by hostname restrictions, regardless of whether
1331 the double-reverse fails or not, CGIs will still be passed the
1332 single-reverse result in <code>REMOTE_HOST</code>.</p>
1334 <p>The default is <code>Off</code> in order to save the network
1335 traffic for those sites that don't truly need the reverse
1336 lookups done. It is also better for the end users because they
1337 don't have to suffer the extra latency that a lookup entails.
1338 Heavily loaded sites should leave this directive
1339 <code>Off</code>, since DNS lookups can take considerable
1340 amounts of time. The utility <code class="program"><a href="../programs/logresolve.html">logresolve</a></code>, compiled by
1341 default to the <code>bin</code> subdirectory of your installation
1342 directory, can be used to look up host names from logged IP addresses
1346 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1347 <div class="directive-section"><h2><a name="If" id="If"><If></a> <a name="if" id="if">Directive</a></h2>
1348 <table class="directive">
1349 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is
1350 satisfied by a request at runtime</td></tr>
1351 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><If <var>expression</var>> ... </If></code></td></tr>
1352 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1353 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1354 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1355 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1357 <p>The <code class="directive"><If></code> directive
1358 evaluates an expression at runtime, and applies the enclosed
1359 directives if and only if the expression evaluates to true.
1362 <div class="example"><p><code>
1363 <If "$req{Host} = ''">
1366 <p>would match HTTP/1.0 requests without a <var>Host:</var> header.</p>
1368 <p>You may compare the value of any variable in the request headers
1369 ($req), response headers ($resp) or environment ($env) in your
1374 <li><a href="../sections.html">How <Directory>, <Location>,
1375 <Files> sections work</a> for an explanation of how these
1376 different sections are combined when a request is received.
1377 <code class="directive"><If></code> has the same precedence
1378 and usage as <code class="directive"><Files></code></li>
1381 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1382 <div class="directive-section"><h2><a name="IfDefine" id="IfDefine"><IfDefine></a> <a name="ifdefine" id="ifdefine">Directive</a></h2>
1383 <table class="directive">
1384 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that will be processed only
1385 if a test is true at startup</td></tr>
1386 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfDefine [!]<var>parameter-name</var>> ...
1387 </IfDefine></code></td></tr>
1388 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1389 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1390 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1391 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1393 <p>The <code><IfDefine <var>test</var>>...</IfDefine>
1394 </code> section is used to mark directives that are conditional. The
1395 directives within an <code class="directive"><IfDefine></code>
1396 section are only processed if the <var>test</var> is true. If <var>
1397 test</var> is false, everything between the start and end markers is
1400 <p>The <var>test</var> in the <code class="directive"><IfDefine></code> section directive can be one of two forms:</p>
1403 <li><var>parameter-name</var></li>
1405 <li><code>!</code><var>parameter-name</var></li>
1408 <p>In the former case, the directives between the start and end
1409 markers are only processed if the parameter named
1410 <var>parameter-name</var> is defined. The second format reverses
1411 the test, and only processes the directives if
1412 <var>parameter-name</var> is <strong>not</strong> defined.</p>
1414 <p>The <var>parameter-name</var> argument is a define as given on the
1415 <code class="program"><a href="../programs/httpd.html">httpd</a></code> command line via <code>-D<var>parameter</var>
1416 </code> at the time the server was started or by the <code class="directive"><a href="#define">Define</a></code> directive.</p>
1418 <p><code class="directive"><IfDefine></code> sections are
1419 nest-able, which can be used to implement simple
1420 multiple-parameter tests. Example:</p>
1422 <div class="example"><p><code>
1423 httpd -DReverseProxy -DUseCache -DMemCache ...<br />
1426 <IfDefine ReverseProxy><br />
1427 <span class="indent">
1428 LoadModule proxy_module modules/mod_proxy.so<br />
1429 LoadModule proxy_http_module modules/mod_proxy_http.so<br />
1430 <IfDefine UseCache><br />
1431 <span class="indent">
1432 LoadModule cache_module modules/mod_cache.so<br />
1433 <IfDefine MemCache><br />
1434 <span class="indent">
1435 LoadModule mem_cache_module modules/mod_mem_cache.so<br />
1437 </IfDefine><br />
1438 <IfDefine !MemCache><br />
1439 <span class="indent">
1440 LoadModule disk_cache_module modules/mod_disk_cache.so<br />
1450 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1451 <div class="directive-section"><h2><a name="IfModule" id="IfModule"><IfModule></a> <a name="ifmodule" id="ifmodule">Directive</a></h2>
1452 <table class="directive">
1453 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that are processed conditional on the
1454 presence or absence of a specific module</td></tr>
1455 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfModule [!]<var>module-file</var>|<var>module-identifier</var>> ...
1456 </IfModule></code></td></tr>
1457 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1458 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1459 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1460 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1461 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Module identifiers are available in version 2.1 and
1464 <p>The <code><IfModule <var>test</var>>...</IfModule></code>
1465 section is used to mark directives that are conditional on the presence of
1466 a specific module. The directives within an <code class="directive"><IfModule></code> section are only processed if the <var>test</var>
1467 is true. If <var>test</var> is false, everything between the start and
1468 end markers is ignored.</p>
1470 <p>The <var>test</var> in the <code class="directive"><IfModule></code> section directive can be one of two forms:</p>
1473 <li><var>module</var></li>
1475 <li>!<var>module</var></li>
1478 <p>In the former case, the directives between the start and end
1479 markers are only processed if the module named <var>module</var>
1480 is included in Apache httpd -- either compiled in or
1481 dynamically loaded using <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code>. The second format reverses the test,
1482 and only processes the directives if <var>module</var> is
1483 <strong>not</strong> included.</p>
1485 <p>The <var>module</var> argument can be either the module identifier or
1486 the file name of the module, at the time it was compiled. For example,
1487 <code>rewrite_module</code> is the identifier and
1488 <code>mod_rewrite.c</code> is the file name. If a module consists of
1489 several source files, use the name of the file containing the string
1490 <code>STANDARD20_MODULE_STUFF</code>.</p>
1492 <p><code class="directive"><IfModule></code> sections are
1493 nest-able, which can be used to implement simple multiple-module
1496 <div class="note">This section should only be used if you need to have one
1497 configuration file that works whether or not a specific module
1498 is available. In normal operation, directives need not be
1499 placed in <code class="directive"><IfModule></code>
1503 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1504 <div class="directive-section"><h2><a name="Include" id="Include">Include</a> <a name="include" id="include">Directive</a></h2>
1505 <table class="directive">
1506 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
1507 the server configuration files</td></tr>
1508 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Include [<var>optional</var>|<var>strict</var>] <var>file-path</var>|<var>directory-path</var>|<var>wildcard</var></code></td></tr>
1509 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1510 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1511 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1512 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Wildcard matching available in 2.0.41 and later, directory
1513 wildcard matching available in 2.3.6 and later</td></tr>
1515 <p>This directive allows inclusion of other configuration files
1516 from within the server configuration files.</p>
1518 <p>Shell-style (<code>fnmatch()</code>) wildcard characters can be used
1519 in the filename or directory parts of the path to include several files
1520 at once, in alphabetical order. In addition, if
1521 <code class="directive">Include</code> points to a directory, rather than a file,
1522 Apache httpd will read all files in that directory and any subdirectory.
1523 However, including entire directories is not recommended, because it is
1524 easy to accidentally leave temporary files in a directory that can cause
1525 <code class="program"><a href="../programs/httpd.html">httpd</a></code> to fail. Instead, we encourage you to use the
1526 wildcard syntax shown below, to include files that match a particular
1527 pattern, such as *.conf, for example.</p>
1529 <p>When a wildcard is specified for a <strong>file</strong> component of
1530 the path, and no file matches the wildcard, the
1531 <code class="directive"><a href="#include">Include</a></code>
1532 directive will be <strong>silently ignored</strong>. When a wildcard is
1533 specified for a <strong>directory</strong> component of the path, and
1534 no directory matches the wildcard, the
1535 <code class="directive"><a href="#include">Include</a></code> directive will
1536 <strong>fail with an error</strong> saying the directory cannot be found.
1539 <p>For further control over the behaviour of the server when no files or
1540 directories match, prefix the path with the modifiers <var>optional</var>
1541 or <var>strict</var>. If <var>optional</var> is specified, any wildcard
1542 file or directory that does not match will be silently ignored. If
1543 <var>strict</var> is specified, any wildcard file or directory that does
1544 not match at least one file will cause server startup to fail.</p>
1546 <p>When a directory or file component of the path is
1547 specified exactly, and that directory or file does not exist,
1548 <code class="directive"><a href="#include">Include</a></code> directive will fail with an
1549 error saying the file or directory cannot be found.</p>
1551 <p>The file path specified may be an absolute path, or may be relative
1552 to the <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory.</p>
1556 <div class="example"><p><code>
1557 Include /usr/local/apache2/conf/ssl.conf<br />
1558 Include /usr/local/apache2/conf/vhosts/*.conf
1561 <p>Or, providing paths relative to your <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory:</p>
1563 <div class="example"><p><code>
1564 Include conf/ssl.conf<br />
1565 Include conf/vhosts/*.conf
1568 <p>Wildcards may be included in the directory or file portion of the
1569 path. In the following example, the server will fail to load if no
1570 directories match conf/vhosts/*, but will load successfully if no
1571 files match *.conf.</p>
1573 <div class="example"><p><code>
1574 Include conf/vhosts/*/vhost.conf<br />
1575 Include conf/vhosts/*/*.conf
1578 <p>In this example, the server will fail to load if either
1579 conf/vhosts/* matches no directories, or if *.conf matches no files:</p>
1581 <div class="example"><p><code>
1582 Include strict conf/vhosts/*/*.conf
1585 <p>In this example, the server load successfully if either conf/vhosts/*
1586 matches no directories, or if *.conf matches no files:</p>
1588 <div class="example"><p><code>
1589 Include optional conf/vhosts/*/*.conf
1595 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
1598 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1599 <div class="directive-section"><h2><a name="KeepAlive" id="KeepAlive">KeepAlive</a> <a name="keepalive" id="keepalive">Directive</a></h2>
1600 <table class="directive">
1601 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables HTTP persistent connections</td></tr>
1602 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAlive On|Off</code></td></tr>
1603 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAlive On</code></td></tr>
1604 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1605 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1606 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1608 <p>The Keep-Alive extension to HTTP/1.0 and the persistent
1609 connection feature of HTTP/1.1 provide long-lived HTTP sessions
1610 which allow multiple requests to be sent over the same TCP
1611 connection. In some cases this has been shown to result in an
1612 almost 50% speedup in latency times for HTML documents with
1613 many images. To enable Keep-Alive connections, set
1614 <code>KeepAlive On</code>.</p>
1616 <p>For HTTP/1.0 clients, Keep-Alive connections will only be
1617 used if they are specifically requested by a client. In
1618 addition, a Keep-Alive connection with an HTTP/1.0 client can
1619 only be used when the length of the content is known in
1620 advance. This implies that dynamic content such as CGI output,
1621 SSI pages, and server-generated directory listings will
1622 generally not use Keep-Alive connections to HTTP/1.0 clients.
1623 For HTTP/1.1 clients, persistent connections are the default
1624 unless otherwise specified. If the client requests it, chunked
1625 encoding will be used in order to send content of unknown
1626 length over persistent connections.</p>
1628 <p>When a client uses a Keep-Alive connection it will be counted
1629 as a single "request" for the <code class="directive"><a href="../mod/mpm_common.html#maxrequestsperchild">MaxRequestsPerChild</a></code> directive, regardless
1630 of how many requests are sent using the connection.</p>
1634 <li><code class="directive"><a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></code></li>
1637 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1638 <div class="directive-section"><h2><a name="KeepAliveTimeout" id="KeepAliveTimeout">KeepAliveTimeout</a> <a name="keepalivetimeout" id="keepalivetimeout">Directive</a></h2>
1639 <table class="directive">
1640 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for subsequent
1641 requests on a persistent connection</td></tr>
1642 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAliveTimeout <var>num</var>[ms]</code></td></tr>
1643 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAliveTimeout 5</code></td></tr>
1644 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1645 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1646 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1647 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Specifying a value in milliseconds is available in
1648 Apache httpd 2.3.2 and later</td></tr>
1650 <p>The number of seconds Apache httpd will wait for a subsequent
1651 request before closing the connection. By adding a postfix of ms the
1652 timeout can be also set in milliseconds. Once a request has been
1653 received, the timeout value specified by the
1654 <code class="directive"><a href="#timeout">Timeout</a></code> directive applies.</p>
1656 <p>Setting <code class="directive">KeepAliveTimeout</code> to a high value
1657 may cause performance problems in heavily loaded servers. The
1658 higher the timeout, the more server processes will be kept
1659 occupied waiting on connections with idle clients.</p>
1661 <p>In a name-based virtual host context, the value of the first
1662 defined virtual host (the default host) in a set of <code class="directive"><a href="#namevirtualhost">NameVirtualHost</a></code> will be used.
1663 The other values will be ignored.</p>
1666 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1667 <div class="directive-section"><h2><a name="Limit" id="Limit"><Limit></a> <a name="limit" id="limit">Directive</a></h2>
1668 <table class="directive">
1669 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict enclosed access controls to only certain HTTP
1671 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Limit <var>method</var> [<var>method</var>] ... > ...
1672 </Limit></code></td></tr>
1673 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
1674 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
1675 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1676 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1678 <p>Access controls are normally effective for
1679 <strong>all</strong> access methods, and this is the usual
1680 desired behavior. <strong>In the general case, access control
1681 directives should not be placed within a
1682 <code class="directive"><Limit></code> section.</strong></p>
1684 <p>The purpose of the <code class="directive"><Limit></code>
1685 directive is to restrict the effect of the access controls to the
1686 nominated HTTP methods. For all other methods, the access
1687 restrictions that are enclosed in the <code class="directive"><Limit></code> bracket <strong>will have no
1688 effect</strong>. The following example applies the access control
1689 only to the methods <code>POST</code>, <code>PUT</code>, and
1690 <code>DELETE</code>, leaving all other methods unprotected:</p>
1692 <div class="example"><p><code>
1693 <Limit POST PUT DELETE><br />
1694 <span class="indent">
1695 Require valid-user<br />
1700 <p>The method names listed can be one or more of: <code>GET</code>,
1701 <code>POST</code>, <code>PUT</code>, <code>DELETE</code>,
1702 <code>CONNECT</code>, <code>OPTIONS</code>,
1703 <code>PATCH</code>, <code>PROPFIND</code>, <code>PROPPATCH</code>,
1704 <code>MKCOL</code>, <code>COPY</code>, <code>MOVE</code>,
1705 <code>LOCK</code>, and <code>UNLOCK</code>. <strong>The method name is
1706 case-sensitive.</strong> If <code>GET</code> is used it will also
1707 restrict <code>HEAD</code> requests. The <code>TRACE</code> method
1708 cannot be limited (see <code class="directive"><a href="#traceenable">TraceEnable</a></code>).</p>
1710 <div class="warning">A <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section should always be
1711 used in preference to a <code class="directive"><Limit></code>
1712 section when restricting access, since a <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section provides protection
1713 against arbitrary methods.</div>
1715 <p>The <code class="directive"><Limit></code> and
1716 <code class="directive"><a href="#limitexcept"><LimitExcept></a></code>
1717 directives may be nested. In this case, each successive level of
1718 <code class="directive"><Limit></code> or <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> directives must
1719 further restrict the set of methods to which access controls apply.</p>
1721 <div class="warning">When using
1722 <code class="directive"><Limit></code> or
1723 <code class="directive"><LimitExcept></code> directives with
1724 the <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directive,
1725 note that the first <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code>
1726 to succeed authorizes the request, regardless of the presence of other
1727 <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directives.</div>
1729 <p>For example, given the following configuration, all users will
1730 be authorized for <code>POST</code> requests, and the
1731 <code>Require group editors</code> directive will be ignored
1734 <div class="example"><p><code>
1735 <LimitExcept GET>
1736 <span class="indent">
1739 </LimitExcept><br />
1741 <span class="indent">
1742 Require group editors
1748 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1749 <div class="directive-section"><h2><a name="LimitExcept" id="LimitExcept"><LimitExcept></a> <a name="limitexcept" id="limitexcept">Directive</a></h2>
1750 <table class="directive">
1751 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict access controls to all HTTP methods
1752 except the named ones</td></tr>
1753 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LimitExcept <var>method</var> [<var>method</var>] ... > ...
1754 </LimitExcept></code></td></tr>
1755 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
1756 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
1757 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1758 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1760 <p><code class="directive"><LimitExcept></code> and
1761 <code></LimitExcept></code> are used to enclose
1762 a group of access control directives which will then apply to any
1763 HTTP access method <strong>not</strong> listed in the arguments;
1764 i.e., it is the opposite of a <code class="directive"><a href="#limit"><Limit></a></code> section and can be used to control
1765 both standard and nonstandard/unrecognized methods. See the
1766 documentation for <code class="directive"><a href="#limit"><Limit></a></code> for more details.</p>
1770 <div class="example"><p><code>
1771 <LimitExcept POST GET><br />
1772 <span class="indent">
1773 Require valid-user<br />
1775 </LimitExcept>
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="LimitInternalRecursion" id="LimitInternalRecursion">LimitInternalRecursion</a> <a name="limitinternalrecursion" id="limitinternalrecursion">Directive</a></h2>
1782 <table class="directive">
1783 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine maximum number of internal redirects and nested
1784 subrequests</td></tr>
1785 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitInternalRecursion <var>number</var> [<var>number</var>]</code></td></tr>
1786 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitInternalRecursion 10</code></td></tr>
1787 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</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>
1790 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.0.47 and later</td></tr>
1792 <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
1793 redirects the original request to a CGI script. A subrequest is Apache httpd's
1794 mechanism to find out what would happen for some URI if it were requested.
1795 For example, <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> uses subrequests to look for the
1796 files listed in the <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
1799 <p><code class="directive">LimitInternalRecursion</code> prevents the server
1800 from crashing when entering an infinite loop of internal redirects or
1801 subrequests. Such loops are usually caused by misconfigurations.</p>
1803 <p>The directive stores two different limits, which are evaluated on
1804 per-request basis. The first <var>number</var> is the maximum number of
1805 internal redirects, that may follow each other. The second <var>number</var>
1806 determines, how deep subrequests may be nested. If you specify only one
1807 <var>number</var>, it will be assigned to both limits.</p>
1809 <div class="example"><h3>Example</h3><p><code>
1810 LimitInternalRecursion 5
1814 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1815 <div class="directive-section"><h2><a name="LimitRequestBody" id="LimitRequestBody">LimitRequestBody</a> <a name="limitrequestbody" id="limitrequestbody">Directive</a></h2>
1816 <table class="directive">
1817 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restricts the total size of the HTTP request body sent
1818 from the client</td></tr>
1819 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestBody <var>bytes</var></code></td></tr>
1820 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestBody 0</code></td></tr>
1821 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1822 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1823 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1824 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1826 <p>This directive specifies the number of <var>bytes</var> from 0
1827 (meaning unlimited) to 2147483647 (2GB) that are allowed in a
1830 <p>The <code class="directive">LimitRequestBody</code> directive allows
1831 the user to set a limit on the allowed size of an HTTP request
1832 message body within the context in which the directive is given
1833 (server, per-directory, per-file or per-location). If the client
1834 request exceeds that limit, the server will return an error
1835 response instead of servicing the request. The size of a normal
1836 request message body will vary greatly depending on the nature of
1837 the resource and the methods allowed on that resource. CGI scripts
1838 typically use the message body for retrieving form information.
1839 Implementations of the <code>PUT</code> method will require
1840 a value at least as large as any representation that the server
1841 wishes to accept for that resource.</p>
1843 <p>This directive gives the server administrator greater
1844 control over abnormal client request behavior, which may be
1845 useful for avoiding some forms of denial-of-service
1848 <p>If, for example, you are permitting file upload to a particular
1849 location, and wish to limit the size of the uploaded file to 100K,
1850 you might use the following directive:</p>
1852 <div class="example"><p><code>
1853 LimitRequestBody 102400
1858 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1859 <div class="directive-section"><h2><a name="LimitRequestFields" id="LimitRequestFields">LimitRequestFields</a> <a name="limitrequestfields" id="limitrequestfields">Directive</a></h2>
1860 <table class="directive">
1861 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of HTTP request header fields that
1862 will be accepted from the client</td></tr>
1863 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFields <var>number</var></code></td></tr>
1864 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFields 100</code></td></tr>
1865 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
1866 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1867 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1869 <p><var>Number</var> is an integer from 0 (meaning unlimited) to
1870 32767. The default value is defined by the compile-time
1871 constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
1874 <p>The <code class="directive">LimitRequestFields</code> directive allows
1875 the server administrator to modify the limit on the number of
1876 request header fields allowed in an HTTP request. A server needs
1877 this value to be larger than the number of fields that a normal
1878 client request might include. The number of request header fields
1879 used by a client rarely exceeds 20, but this may vary among
1880 different client implementations, often depending upon the extent
1881 to which a user has configured their browser to support detailed
1882 content negotiation. Optional HTTP extensions are often expressed
1883 using request header fields.</p>
1885 <p>This directive gives the server administrator greater
1886 control over abnormal client request behavior, which may be
1887 useful for avoiding some forms of denial-of-service attacks.
1888 The value should be increased if normal clients see an error
1889 response from the server that indicates too many fields were
1890 sent in the request.</p>
1894 <div class="example"><p><code>
1895 LimitRequestFields 50
1900 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1901 <div class="directive-section"><h2><a name="LimitRequestFieldSize" id="LimitRequestFieldSize">LimitRequestFieldSize</a> <a name="limitrequestfieldsize" id="limitrequestfieldsize">Directive</a></h2>
1902 <table class="directive">
1903 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of the HTTP request header allowed from the
1905 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFieldSize <var>bytes</var></code></td></tr>
1906 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFieldSize 8190</code></td></tr>
1907 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
1908 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1909 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1911 <p>This directive specifies the number of <var>bytes</var>
1912 that will be allowed in an HTTP request header.</p>
1914 <p>The <code class="directive">LimitRequestFieldSize</code> directive
1915 allows the server administrator to reduce or increase the limit
1916 on the allowed size of an HTTP request header field. A server
1917 needs this value to be large enough to hold any one header field
1918 from a normal client request. The size of a normal request header
1919 field will vary greatly among different client implementations,
1920 often depending upon the extent to which a user has configured
1921 their browser to support detailed content negotiation. SPNEGO
1922 authentication headers can be up to 12392 bytes.</p>
1924 <p>This directive gives the server administrator greater
1925 control over abnormal client request behavior, which may be
1926 useful for avoiding some forms of denial-of-service attacks.</p>
1930 <div class="example"><p><code>
1931 LimitRequestFieldSize 4094
1934 <div class="note">Under normal conditions, the value should not be changed from
1939 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1940 <div class="directive-section"><h2><a name="LimitRequestLine" id="LimitRequestLine">LimitRequestLine</a> <a name="limitrequestline" id="limitrequestline">Directive</a></h2>
1941 <table class="directive">
1942 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limit the size of the HTTP request line that will be accepted
1943 from the client</td></tr>
1944 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestLine <var>bytes</var></code></td></tr>
1945 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestLine 8190</code></td></tr>
1946 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
1947 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1948 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1950 <p>This directive sets the number of <var>bytes</var> that will be
1951 allowed on the HTTP request-line.</p>
1953 <p>The <code class="directive">LimitRequestLine</code> directive allows
1954 the server administrator to reduce or increase the limit on the allowed size
1955 of a client's HTTP request-line. Since the request-line consists of the
1956 HTTP method, URI, and protocol version, the
1957 <code class="directive">LimitRequestLine</code> directive places a
1958 restriction on the length of a request-URI allowed for a request
1959 on the server. A server needs this value to be large enough to
1960 hold any of its resource names, including any information that
1961 might be passed in the query part of a <code>GET</code> request.</p>
1963 <p>This directive gives the server administrator greater
1964 control over abnormal client request behavior, which may be
1965 useful for avoiding some forms of denial-of-service attacks.</p>
1969 <div class="example"><p><code>
1970 LimitRequestLine 4094
1973 <div class="note">Under normal conditions, the value should not be changed from
1977 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1978 <div class="directive-section"><h2><a name="LimitXMLRequestBody" id="LimitXMLRequestBody">LimitXMLRequestBody</a> <a name="limitxmlrequestbody" id="limitxmlrequestbody">Directive</a></h2>
1979 <table class="directive">
1980 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of an XML-based request body</td></tr>
1981 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitXMLRequestBody <var>bytes</var></code></td></tr>
1982 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitXMLRequestBody 1000000</code></td></tr>
1983 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1984 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1985 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1986 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1988 <p>Limit (in bytes) on maximum size of an XML-based request
1989 body. A value of <code>0</code> will disable any checking.</p>
1993 <div class="example"><p><code>
1994 LimitXMLRequestBody 0
1999 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2000 <div class="directive-section"><h2><a name="Location" id="Location"><Location></a> <a name="location" id="location">Directive</a></h2>
2001 <table class="directive">
2002 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to matching
2004 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Location
2005 <var>URL-path</var>|<var>URL</var>> ... </Location></code></td></tr>
2006 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2007 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2008 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2010 <p>The <code class="directive"><Location></code> directive
2011 limits the scope of the enclosed directives by URL. It is similar to the
2012 <code class="directive"><a href="#directory"><Directory></a></code>
2013 directive, and starts a subsection which is terminated with a
2014 <code></Location></code> directive. <code class="directive"><Location></code> sections are processed in the
2015 order they appear in the configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
2016 <code>.htaccess</code> files are read, and after the <code class="directive"><a href="#files"><Files></a></code> sections.</p>
2018 <p><code class="directive"><Location></code> sections operate
2019 completely outside the filesystem. This has several consequences.
2020 Most importantly, <code class="directive"><Location></code>
2021 directives should not be used to control access to filesystem
2022 locations. Since several different URLs may map to the same
2023 filesystem location, such access controls may by circumvented.</p>
2025 <div class="note"><h3>When to use <code class="directive"><Location></code></h3>
2027 <p>Use <code class="directive"><Location></code> to apply
2028 directives to content that lives outside the filesystem. For
2029 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
2030 <code><Location /></code>, which is an easy way to
2031 apply a configuration to the entire server.</p>
2034 <p>For all origin (non-proxy) requests, the URL to be matched is a
2035 URL-path of the form <code>/path/</code>. <em>No scheme, hostname,
2036 port, or query string may be included.</em> For proxy requests, the
2037 URL to be matched is of the form
2038 <code>scheme://servername/path</code>, and you must include the
2041 <p>The URL may use wildcards. In a wild-card string, <code>?</code> matches
2042 any single character, and <code>*</code> matches any sequences of
2043 characters. Neither wildcard character matches a / in the URL-path.</p>
2045 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
2046 can also be used, with the addition of the <code>~</code>
2047 character. For example:</p>
2049 <div class="example"><p><code>
2050 <Location ~ "/(extra|special)/data">
2053 <p>would match URLs that contained the substring <code>/extra/data</code>
2054 or <code>/special/data</code>. The directive <code class="directive"><a href="#locationmatch"><LocationMatch></a></code> behaves
2055 identical to the regex version of <code class="directive"><Location></code>, and is preferred, for the
2056 simple reason that <code>~</code> is hard to distinguish from
2057 <code>-</code> in many fonts.</p>
2059 <p>The <code class="directive"><Location></code>
2060 functionality is especially useful when combined with the
2061 <code class="directive"><a href="#sethandler">SetHandler</a></code>
2062 directive. For example, to enable status requests, but allow them
2063 only from browsers at <code>example.com</code>, you might use:</p>
2065 <div class="example"><p><code>
2066 <Location /status><br />
2067 <span class="indent">
2068 SetHandler server-status<br />
2069 Order Deny,Allow<br />
2071 Allow from .example.com<br />
2076 <div class="note"><h3>Note about / (slash)</h3>
2077 <p>The slash character has special meaning depending on where in a
2078 URL it appears. People may be used to its behavior in the filesystem
2079 where multiple adjacent slashes are frequently collapsed to a single
2080 slash (<em>i.e.</em>, <code>/home///foo</code> is the same as
2081 <code>/home/foo</code>). In URL-space this is not necessarily true.
2082 The <code class="directive"><a href="#locationmatch"><LocationMatch></a></code>
2083 directive and the regex version of <code class="directive"><Location></code> require you to explicitly specify multiple
2084 slashes if that is your intention.</p>
2086 <p>For example, <code><LocationMatch ^/abc></code> would match
2087 the request URL <code>/abc</code> but not the request URL <code>
2088 //abc</code>. The (non-regex) <code class="directive"><Location></code> directive behaves similarly when used for
2089 proxy requests. But when (non-regex) <code class="directive"><Location></code> is used for non-proxy requests it will
2090 implicitly match multiple slashes with a single slash. For example,
2091 if you specify <code><Location /abc/def></code> and the
2092 request is to <code>/abc//def</code> then it will match.</p>
2097 <li><a href="../sections.html">How <Directory>, <Location>
2098 and <Files> sections work</a> for an explanation of how these
2099 different sections are combined when a request is received.</li>
2100 <li><code class="directive"><a href="#locationmatch">LocationMatch</a></code></li>
2103 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2104 <div class="directive-section"><h2><a name="LocationMatch" id="LocationMatch"><LocationMatch></a> <a name="locationmatch" id="locationmatch">Directive</a></h2>
2105 <table class="directive">
2106 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to regular-expression
2107 matching URLs</td></tr>
2108 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LocationMatch
2109 <var>regex</var>> ... </LocationMatch></code></td></tr>
2110 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2111 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2112 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2114 <p>The <code class="directive"><LocationMatch></code> directive
2115 limits the scope of the enclosed directives by URL, in an identical manner
2116 to <code class="directive"><a href="#location"><Location></a></code>. However,
2117 it takes a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>
2118 as an argument instead of a simple string. For example:</p>
2120 <div class="example"><p><code>
2121 <LocationMatch "/(extra|special)/data">
2124 <p>would match URLs that contained the substring <code>/extra/data</code>
2125 or <code>/special/data</code>.</p>
2129 <li><a href="../sections.html">How <Directory>, <Location>
2130 and <Files> sections work</a> for an explanation of how these
2131 different sections are combined when a request is received</li>
2134 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2135 <div class="directive-section"><h2><a name="LogLevel" id="LogLevel">LogLevel</a> <a name="loglevel" id="loglevel">Directive</a></h2>
2136 <table class="directive">
2137 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls the verbosity of the ErrorLog</td></tr>
2138 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel [<var>module</var>:]<var>level</var>
2139 [<var>module</var>:<var>level</var>] ...
2141 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LogLevel warn</code></td></tr>
2142 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2143 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2144 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2145 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Per-module and per-directory configuration is available in
2146 Apache HTTP Server 2.3.6 and later</td></tr>
2148 <p><code class="directive">LogLevel</code> adjusts the verbosity of the
2149 messages recorded in the error logs (see <code class="directive"><a href="#errorlog">ErrorLog</a></code> directive). The following
2150 <var>level</var>s are available, in order of decreasing
2153 <table class="bordered">
2156 <th><strong>Level</strong> </th>
2158 <th><strong>Description</strong> </th>
2160 <th><strong>Example</strong> </th>
2164 <td><code>emerg</code> </td>
2166 <td>Emergencies - system is unusable.</td>
2168 <td>"Child cannot open lock file. Exiting"</td>
2172 <td><code>alert</code> </td>
2174 <td>Action must be taken immediately.</td>
2176 <td>"getpwuid: couldn't determine user name from uid"</td>
2180 <td><code>crit</code> </td>
2182 <td>Critical Conditions.</td>
2184 <td>"socket: Failed to get a socket, exiting child"</td>
2188 <td><code>error</code> </td>
2190 <td>Error conditions.</td>
2192 <td>"Premature end of script headers"</td>
2196 <td><code>warn</code> </td>
2198 <td>Warning conditions.</td>
2200 <td>"child process 1234 did not exit, sending another
2205 <td><code>notice</code> </td>
2207 <td>Normal but significant condition.</td>
2209 <td>"httpd: caught SIGBUS, attempting to dump core in
2214 <td><code>info</code> </td>
2216 <td>Informational.</td>
2218 <td>"Server seems busy, (you may need to increase
2219 StartServers, or Min/MaxSpareServers)..."</td>
2223 <td><code>debug</code> </td>
2225 <td>Debug-level messages</td>
2227 <td>"Opening config file ..."</td>
2230 <td><code>trace1</code> </td>
2232 <td>Trace messages</td>
2234 <td>"proxy: FTP: control connection complete"</td>
2237 <td><code>trace2</code> </td>
2239 <td>Trace messages</td>
2241 <td>"proxy: CONNECT: sending the CONNECT request to the remote proxy"</td>
2244 <td><code>trace3</code> </td>
2246 <td>Trace messages</td>
2248 <td>"openssl: Handshake: start"</td>
2251 <td><code>trace4</code> </td>
2253 <td>Trace messages</td>
2255 <td>"read from buffered SSL brigade, mode 0, 17 bytes"</td>
2258 <td><code>trace5</code> </td>
2260 <td>Trace messages</td>
2262 <td>"map lookup FAILED: map=rewritemap key=keyname"</td>
2265 <td><code>trace6</code> </td>
2267 <td>Trace messages</td>
2269 <td>"cache lookup FAILED, forcing new map lookup"</td>
2272 <td><code>trace7</code> </td>
2274 <td>Trace messages, dumping large amounts of data</td>
2276 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
2279 <td><code>trace8</code> </td>
2281 <td>Trace messages, dumping large amounts of data</td>
2283 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
2287 <p>When a particular level is specified, messages from all
2288 other levels of higher significance will be reported as well.
2289 <em>E.g.</em>, when <code>LogLevel info</code> is specified,
2290 then messages with log levels of <code>notice</code> and
2291 <code>warn</code> will also be posted.</p>
2293 <p>Using a level of at least <code>crit</code> is
2298 <div class="example"><p><code>
2302 <div class="note"><h3>Note</h3>
2303 <p>When logging to a regular file messages of the level
2304 <code>notice</code> cannot be suppressed and thus are always
2305 logged. However, this doesn't apply when logging is done
2306 using <code>syslog</code>.</p>
2309 <p>Specifying a level without a module name will reset the level
2310 for all modules to that level. Specifying a level with a module
2311 name will set the level for that module only. It is possible to
2312 use the module source file name, the module identifier, or the
2313 module identifier with the trailing <code>_module</code> omitted
2314 as module specification. This means the following three specifications
2317 <div class="example"><p><code>
2318 LogLevel info ssl:warn<br />
2319 LogLevel info mod_ssl.c:warn<br />
2320 LogLevel info ssl_module:warn<br />
2323 <p>It is also possible to change the level per directory:</p>
2325 <div class="example"><p><code>
2327 <Directory /usr/local/apache/htdocs/app><br />
2328 LogLevel debug<br />
2333 Per directory loglevel configuration only affects messages that are
2334 logged after the request has been parsed and that are associated with
2335 the request. Log messages which are associated with the connection or
2336 the server are not affected.
2340 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2341 <div class="directive-section"><h2><a name="MaxKeepAliveRequests" id="MaxKeepAliveRequests">MaxKeepAliveRequests</a> <a name="maxkeepaliverequests" id="maxkeepaliverequests">Directive</a></h2>
2342 <table class="directive">
2343 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of requests allowed on a persistent
2344 connection</td></tr>
2345 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxKeepAliveRequests <var>number</var></code></td></tr>
2346 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxKeepAliveRequests 100</code></td></tr>
2347 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2348 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2349 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2351 <p>The <code class="directive">MaxKeepAliveRequests</code> directive
2352 limits the number of requests allowed per connection when
2353 <code class="directive"><a href="#keepalive">KeepAlive</a></code> is on. If it is
2354 set to <code>0</code>, unlimited requests will be allowed. We
2355 recommend that this setting be kept to a high value for maximum
2356 server performance.</p>
2360 <div class="example"><p><code>
2361 MaxKeepAliveRequests 500
2365 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2366 <div class="directive-section"><h2><a name="Mutex" id="Mutex">Mutex</a> <a name="mutex" id="mutex">Directive</a></h2>
2367 <table class="directive">
2368 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures mutex mechanism and lock file directory for all
2369 or specified mutexes</td></tr>
2370 <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>
2371 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Mutex default</code></td></tr>
2372 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
2373 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2374 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2375 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.4 and later</td></tr>
2377 <p>The <code class="directive">Mutex</code> directive sets the mechanism,
2378 and optionally the lock file location, that httpd and modules use
2379 to serialize access to resources. Specify <code>default</code> as
2380 the first argument to change the settings for all mutexes; specify
2381 a mutex name (see table below) as the first argument to override
2382 defaults only for that mutex.</p>
2384 <p>The <code class="directive">Mutex</code> directive is typically used in
2385 the following exceptional situations:</p>
2388 <li>change the mutex mechanism when the default mechanism selected
2389 by <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> has a functional or performance
2392 <li>change the directory used by file-based mutexes when the
2393 default directory does not support locking</li>
2396 <div class="note"><h3>Supported modules</h3>
2397 <p>This directive only configures mutexes which have been registered
2398 with the core server using the <code>ap_mutex_register()</code> API.
2399 All modules bundled with httpd support the <code class="directive">Mutex</code>
2400 directive, but third-party modules may not. Consult the documentation
2401 of the third-party module, which must indicate the mutex name(s) which
2402 can be configured if this directive is supported.</p>
2405 <p>The following mutex <em>mechanisms</em> are available:</p>
2407 <li><code>default | yes</code>
2408 <p>This selects the default locking implementation, as determined by
2409 <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a>. The default locking implementation can
2410 be displayed by running <code class="program"><a href="../programs/httpd.html">httpd</a></code> with the
2411 <code>-V</code> option.</p></li>
2413 <li><code>none | no</code>
2414 <p>This effectively disables the mutex, and is only allowed for a
2415 mutex if the module indicates that it is a valid choice. Consult the
2416 module documentation for more information.</p></li>
2418 <li><code>posixsem</code>
2419 <p>This is a mutex variant based on a Posix semaphore.</p>
2421 <div class="warning"><h3>Warning</h3>
2422 <p>The semaphore ownership is not recovered if a thread in the process
2423 holding the mutex segfaults, resulting in a hang of the web server.</p>
2427 <li><code>sysvsem</code>
2428 <p>This is a mutex variant based on a SystemV IPC semaphore.</p>
2430 <div class="warning"><h3>Warning</h3>
2431 <p>It is possible to "leak" SysV semaphores if processes crash
2432 before the semaphore is removed.</p>
2435 <div class="warning"><h3>Security</h3>
2436 <p>The semaphore API allows for a denial of service attack by any
2437 CGIs running under the same uid as the webserver (<em>i.e.</em>,
2438 all CGIs, unless you use something like <code class="program"><a href="../programs/suexec.html">suexec</a></code>
2439 or <code>cgiwrapper</code>).</p>
2443 <li><code>sem</code>
2444 <p>This selects the "best" available semaphore implementation, choosing
2445 between Posix and SystemV IPC semaphores, in that order.</p></li>
2447 <li><code>pthread</code>
2448 <p>This is a mutex variant based on cross-process Posix thread
2451 <div class="warning"><h3>Warning</h3>
2452 <p>On most systems, if a child process terminates abnormally while
2453 holding a mutex that uses this implementation, the server will deadlock
2454 and stop responding to requests. When this occurs, the server will
2455 require a manual restart to recover.</p>
2456 <p>Solaris is a notable exception as it provides a mechanism which
2457 usually allows the mutex to be recovered after a child process
2458 terminates abnormally while holding a mutex.</p>
2459 <p>If your system implements the
2460 <code>pthread_mutexattr_setrobust_np()</code> function, you may be able
2461 to use the <code>pthread</code> option safely.</p>
2465 <li><code>fcntl:/path/to/mutex</code>
2466 <p>This is a mutex variant where a physical (lock-)file and the
2467 <code>fcntl()</code> function are used as the mutex.</p>
2469 <div class="warning"><h3>Warning</h3>
2470 <p>When multiple mutexes based on this mechanism are used within
2471 multi-threaded, multi-process environments, deadlock errors (EDEADLK)
2472 can be reported for valid mutex operations if <code>fcntl()</code>
2473 is not thread-aware, such as on Solaris.</p>
2477 <li><code>flock:/path/to/mutex</code>
2478 <p>This is similar to the <code>fcntl:/path/to/mutex</code> method
2479 with the exception that the <code>flock()</code> function is used to
2480 provide file locking.</p></li>
2482 <li><code>file:/path/to/mutex</code>
2483 <p>This selects the "best" available file locking implementation,
2484 choosing between <code>fcntl</code> and <code>flock</code>, in that
2488 <p>Most mechanisms are only available on selected platforms, where the
2489 underlying platform and <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> support it. Mechanisms
2490 which aren't available on all platforms are <em>posixsem</em>,
2491 <em>sysvsem</em>, <em>sem</em>, <em>pthread</em>, <em>fcntl</em>,
2492 <em>flock</em>, and <em>file</em>.</p>
2494 <p>With the file-based mechanisms <em>fcntl</em> and <em>flock</em>,
2495 the path, if provided, is a directory where the lock file will be created.
2496 The default directory is httpd's run-time file directory relative to
2497 <code class="directive"><a href="#serverroot">ServerRoot</a></code>. Always use a local disk
2498 filesystem for <code>/path/to/mutex</code> and never a directory residing
2499 on a NFS- or AFS-filesystem. The basename of the file will be the mutex
2500 type, an optional instance string provided by the module, and unless the
2501 <code>OmitPID</code> keyword is specified, the process id of the httpd
2502 parent process will be appended to to make the file name unique, avoiding
2503 conflicts when multiple httpd instances share a lock file directory. For
2504 example, if the mutex name is <code>mpm-accept</code> and the lock file
2505 directory is <code>/var/httpd/locks</code>, the lock file name for the
2506 httpd instance with parent process id 12345 would be
2507 <code>/var/httpd/locks/mpm-accept.12345</code>.</p>
2509 <div class="warning"><h3>Security</h3>
2510 <p>It is best to <em>avoid</em> putting mutex files in a world-writable
2511 directory such as <code>/var/tmp</code> because someone could create
2512 a denial of service attack and prevent the server from starting by
2513 creating a lockfile with the same name as the one the server will try
2517 <p>The following table documents the names of mutexes used by httpd
2518 and bundled modules.</p>
2520 <table class="bordered"><tr class="header">
2523 <th>Protected resource</th>
2526 <td><code>mpm-accept</code></td>
2527 <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>
2528 <td>incoming connections, to avoid the thundering herd problem;
2529 for more information, refer to the
2530 <a href="../misc/perf-tuning.html">performance tuning</a>
2534 <td><code>authdigest-client</code></td>
2535 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
2536 <td>client list in shared memory</td>
2539 <td><code>authdigest-opaque</code></td>
2540 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
2541 <td>counter in shared memory</td>
2544 <td><code>ldap-cache</code></td>
2545 <td><code class="module"><a href="../mod/mod_ldap.html">mod_ldap</a></code></td>
2546 <td>LDAP result cache</td>
2549 <td><code>rewrite-map</code></td>
2550 <td><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></td>
2551 <td>communication with external mapping programs, to avoid
2552 intermixed I/O from multiple requests</td>
2555 <td><code>ssl-cache</code></td>
2556 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
2557 <td>SSL session cache</td>
2560 <td><code>ssl-stapling</code></td>
2561 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
2562 <td>OCSP stapling response cache</td>
2565 <td><code>watchdog-callback</code></td>
2566 <td><code class="module"><a href="../mod/mod_watchdog.html">mod_watchdog</a></code></td>
2567 <td>callback function of a particular client module</td>
2571 <p>The <code>OmitPID</code> keyword suppresses the addition of the httpd
2572 parent process id from the lock file name.</p>
2574 <p>In the following example, the mutex mechanism for the MPM accept
2575 mutex will be changed from the compiled-in default to <code>fcntl</code>,
2576 with the associated lock file created in directory
2577 <code>/var/httpd/locks</code>. The mutex mechanism for all other mutexes
2578 will be changed from the compiled-in default to <code>sysvsem</code>.</p>
2580 <div class="example"><p><code>
2581 Mutex default sysvsem<br />
2582 Mutex mpm-accept fcntl:/var/httpd/locks
2586 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2587 <div class="directive-section"><h2><a name="NameVirtualHost" id="NameVirtualHost">NameVirtualHost</a> <a name="namevirtualhost" id="namevirtualhost">Directive</a></h2>
2588 <table class="directive">
2589 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Designates an IP address for name-virtual
2591 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NameVirtualHost <var>addr</var>[:<var>port</var>]</code></td></tr>
2592 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
2593 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2594 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2597 <p>A single <code class="directive">NameVirtualHost</code> directive
2598 identifies a set of identical virtual hosts on which the server will
2599 further select from on the basis of the <em>hostname</em>
2600 requested by the client. The <code class="directive">NameVirtualHost</code>
2601 directive is a required directive if you want to configure
2602 <a href="../vhosts/">name-based virtual hosts</a>.</p>
2604 <p>This directive, and the corresponding <code class="directive">VirtualHost</code>,
2605 <em>must</em> be qualified with a port number if the server supports both HTTP
2606 and HTTPS connections.</p>
2608 <p>Although <var>addr</var> can be a hostname, it is recommended
2609 that you always use an IP address or a wildcard. A wildcard
2610 NameVirtualHost matches only virtualhosts that also have a literal wildcard
2611 as their argument.</p>
2613 <p>In cases where a firewall or other proxy receives the requests and
2614 forwards them on a different IP address to the server, you must specify the
2615 IP address of the physical interface on the machine which will be
2616 servicing the requests. </p>
2618 <p> In the example below, requests received on interface 192.0.2.1 and port 80
2619 will only select among the first two virtual hosts. Requests received on
2620 port 80 on any other interface will only select among the third and fourth
2621 virtual hosts. In the common case where the interface isn't important
2622 to the mapping, only the "*:80" NameVirtualHost and VirtualHost directives
2625 <div class="example"><p><code>
2626 NameVirtualHost 192.0.2.1:80<br />
2627 NameVirtualHost *:80<br /><br />
2629 <VirtualHost 192.0.2.1:80><br />
2630 ServerName namebased-a.example.com<br />
2631 </VirtualHost><br />
2633 <VirtualHost 192.0.2.1:80><br />
2634 Servername namebased-b.example.com<br />
2635 </VirtualHost><br />
2637 <VirtualHost *:80><br />
2638 ServerName namebased-c.example.com <br />
2639 </VirtualHost><br />
2641 <VirtualHost *:80><br />
2642 ServerName namebased-d.example.com <br />
2643 </VirtualHost><br />
2648 <p>If no matching virtual host is found, then the first listed
2649 virtual host that matches the IP address and port will be used.</p>
2652 <p>IPv6 addresses must be enclosed in square brackets, as shown
2653 in the following example:</p>
2655 <div class="example"><p><code>
2656 NameVirtualHost [2001:db8::a00:20ff:fea7:ccea]:8080
2659 <div class="note"><h3>Argument to <code class="directive"><VirtualHost></code>
2661 <p>Note that the argument to the <code class="directive"><VirtualHost></code> directive must
2662 exactly match the argument to the <code class="directive">NameVirtualHost</code> directive.</p>
2664 <div class="example"><p><code>
2665 NameVirtualHost 192.0.2.2:80<br />
2666 <VirtualHost 192.0.2.2:80><br />
2668 </VirtualHost><br />
2674 <li><a href="../vhosts/">Virtual Hosts
2675 documentation</a></li>
2678 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2679 <div class="directive-section"><h2><a name="Options" id="Options">Options</a> <a name="options" id="options">Directive</a></h2>
2680 <table class="directive">
2681 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures what features are available in a particular
2683 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Options
2684 [+|-]<var>option</var> [[+|-]<var>option</var>] ...</code></td></tr>
2685 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Options All</code></td></tr>
2686 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2687 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
2688 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2689 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2691 <p>The <code class="directive">Options</code> directive controls which
2692 server features are available in a particular directory.</p>
2694 <p><var>option</var> can be set to <code>None</code>, in which
2695 case none of the extra features are enabled, or one or more of
2699 <dt><code>All</code></dt>
2701 <dd>All options except for <code>MultiViews</code>. This is the default
2704 <dt><code>ExecCGI</code></dt>
2707 Execution of CGI scripts using <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>
2710 <dt><code>FollowSymLinks</code></dt>
2714 The server will follow symbolic links in this directory.
2716 <p>Even though the server follows the symlink it does <em>not</em>
2717 change the pathname used to match against <code class="directive"><a href="#directory"><Directory></a></code> sections.</p>
2718 <p>Note also, that this option <strong>gets ignored</strong> if set
2719 inside a <code class="directive"><a href="#location"><Location></a></code>
2721 <p>Omitting this option should not be considered a security restriction,
2722 since symlink testing is subject to race conditions that make it
2726 <dt><code>Includes</code></dt>
2729 Server-side includes provided by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
2732 <dt><code>IncludesNOEXEC</code></dt>
2736 Server-side includes are permitted, but the <code>#exec
2737 cmd</code> and <code>#exec cgi</code> are disabled. It is still
2738 possible to <code>#include virtual</code> CGI scripts from
2739 <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>ed
2742 <dt><code>Indexes</code></dt>
2745 If a URL which maps to a directory is requested, and there
2746 is no <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
2747 (<em>e.g.</em>, <code>index.html</code>) in that directory, then
2748 <code class="module"><a href="../mod/mod_autoindex.html">mod_autoindex</a></code> will return a formatted listing
2749 of the directory.</dd>
2751 <dt><code>MultiViews</code></dt>
2754 <a href="../content-negotiation.html">Content negotiated</a>
2755 "MultiViews" are allowed using
2756 <code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code>.</dd>
2758 <dt><code>SymLinksIfOwnerMatch</code></dt>
2760 <dd>The server will only follow symbolic links for which the
2761 target file or directory is owned by the same user id as the
2764 <div class="note"><h3>Note</h3> <p>This option gets ignored if
2765 set inside a <code class="directive"><a href="#location"><Location></a></code> section.</p>
2766 <p>This option should not be considered a security restriction,
2767 since symlink testing is subject to race conditions that make it
2768 circumventable.</p></div>
2772 <p>Normally, if multiple <code class="directive">Options</code> could
2773 apply to a directory, then the most specific one is used and
2774 others are ignored; the options are not merged. (See <a href="../sections.html#mergin">how sections are merged</a>.)
2775 However if <em>all</em> the options on the
2776 <code class="directive">Options</code> directive are preceded by a
2777 <code>+</code> or <code>-</code> symbol, the options are
2778 merged. Any options preceded by a <code>+</code> are added to the
2779 options currently in force, and any options preceded by a
2780 <code>-</code> are removed from the options currently in
2783 <div class="warning"><h3>Warning</h3>
2784 <p>Mixing <code class="directive">Options</code> with a <code>+</code> or
2785 <code>-</code> with those without is not valid syntax, and is likely
2786 to cause unexpected results.</p>
2789 <p>For example, without any <code>+</code> and <code>-</code> symbols:</p>
2791 <div class="example"><p><code>
2792 <Directory /web/docs><br />
2793 <span class="indent">
2794 Options Indexes FollowSymLinks<br />
2796 </Directory><br />
2798 <Directory /web/docs/spec><br />
2799 <span class="indent">
2800 Options Includes<br />
2805 <p>then only <code>Includes</code> will be set for the
2806 <code>/web/docs/spec</code> directory. However if the second
2807 <code class="directive">Options</code> directive uses the <code>+</code> and
2808 <code>-</code> symbols:</p>
2810 <div class="example"><p><code>
2811 <Directory /web/docs><br />
2812 <span class="indent">
2813 Options Indexes FollowSymLinks<br />
2815 </Directory><br />
2817 <Directory /web/docs/spec><br />
2818 <span class="indent">
2819 Options +Includes -Indexes<br />
2824 <p>then the options <code>FollowSymLinks</code> and
2825 <code>Includes</code> are set for the <code>/web/docs/spec</code>
2828 <div class="note"><h3>Note</h3>
2829 <p>Using <code>-IncludesNOEXEC</code> or
2830 <code>-Includes</code> disables server-side includes completely
2831 regardless of the previous setting.</p>
2834 <p>The default in the absence of any other settings is
2835 <code>All</code>.</p>
2838 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2839 <div class="directive-section"><h2><a name="RLimitCPU" id="RLimitCPU">RLimitCPU</a> <a name="rlimitcpu" id="rlimitcpu">Directive</a></h2>
2840 <table class="directive">
2841 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the CPU consumption of processes launched
2842 by Apache httpd children</td></tr>
2843 <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>
2844 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
2845 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2846 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2847 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2848 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2850 <p>Takes 1 or 2 parameters. The first parameter sets the soft
2851 resource limit for all processes and the second parameter sets
2852 the maximum resource limit. Either parameter can be a number,
2853 or <code>max</code> to indicate to the server that the limit should
2854 be set to the maximum allowed by the operating system
2855 configuration. Raising the maximum resource limit requires that
2856 the server is running as <code>root</code>, or in the initial startup
2859 <p>This applies to processes forked off from Apache httpd children
2860 servicing requests, not the Apache httpd children themselves. This
2861 includes CGI scripts and SSI exec commands, but not any
2862 processes forked off from the Apache httpd parent such as piped
2865 <p>CPU resource limits are expressed in seconds per
2870 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
2871 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
2874 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2875 <div class="directive-section"><h2><a name="RLimitMEM" id="RLimitMEM">RLimitMEM</a> <a name="rlimitmem" id="rlimitmem">Directive</a></h2>
2876 <table class="directive">
2877 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the memory consumption of processes launched
2878 by Apache httpd children</td></tr>
2879 <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>
2880 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
2881 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2882 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2883 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2884 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2886 <p>Takes 1 or 2 parameters. The first parameter sets the soft
2887 resource limit for all processes and the second parameter sets
2888 the maximum resource limit. Either parameter can be a number,
2889 or <code>max</code> to indicate to the server that the limit should
2890 be set to the maximum allowed by the operating system
2891 configuration. Raising the maximum resource limit requires that
2892 the server is running as <code>root</code>, or in the initial startup
2895 <p>This applies to processes forked off from Apache httpd children
2896 servicing requests, not the Apache httpd children themselves. This
2897 includes CGI scripts and SSI exec commands, but not any
2898 processes forked off from the Apache httpd parent such as piped
2901 <p>Memory resource limits are expressed in bytes per
2906 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
2907 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
2910 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2911 <div class="directive-section"><h2><a name="RLimitNPROC" id="RLimitNPROC">RLimitNPROC</a> <a name="rlimitnproc" id="rlimitnproc">Directive</a></h2>
2912 <table class="directive">
2913 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of processes that can be launched by
2914 processes launched by Apache httpd children</td></tr>
2915 <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>
2916 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
2917 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2918 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2919 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2920 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2922 <p>Takes 1 or 2 parameters. The first parameter sets the soft
2923 resource limit for all processes and the second parameter sets
2924 the maximum resource limit. Either parameter can be a number,
2925 or <code>max</code> to indicate to the server that the limit
2926 should be set to the maximum allowed by the operating system
2927 configuration. Raising the maximum resource limit requires that
2928 the server is running as <code>root</code>, or in the initial startup
2931 <p>This applies to processes forked off from Apache httpd children
2932 servicing requests, not the Apache httpd children themselves. This
2933 includes CGI scripts and SSI exec commands, but not any
2934 processes forked off from the Apache httpd parent such as piped
2937 <p>Process limits control the number of processes per user.</p>
2939 <div class="note"><h3>Note</h3>
2940 <p>If CGI processes are <strong>not</strong> running
2941 under user ids other than the web server user id, this directive
2942 will limit the number of processes that the server itself can
2943 create. Evidence of this situation will be indicated by
2944 <strong><code>cannot fork</code></strong> messages in the
2945 <code>error_log</code>.</p>
2950 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
2951 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
2954 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2955 <div class="directive-section"><h2><a name="ScriptInterpreterSource" id="ScriptInterpreterSource">ScriptInterpreterSource</a> <a name="scriptinterpretersource" id="scriptinterpretersource">Directive</a></h2>
2956 <table class="directive">
2957 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
2959 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ScriptInterpreterSource Registry|Registry-Strict|Script</code></td></tr>
2960 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ScriptInterpreterSource Script</code></td></tr>
2961 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2962 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
2963 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2964 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2965 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Win32 only;
2966 option <code>Registry-Strict</code> is available in Apache HTTP Server 2.0 and
2969 <p>This directive is used to control how Apache httpd finds the
2970 interpreter used to run CGI scripts. The default setting is
2971 <code>Script</code>. This causes Apache httpd to use the interpreter pointed to
2972 by the shebang line (first line, starting with <code>#!</code>) in the
2973 script. On Win32 systems this line usually looks like:</p>
2975 <div class="example"><p><code>
2976 #!C:/Perl/bin/perl.exe
2979 <p>or, if <code>perl</code> is in the <code>PATH</code>, simply:</p>
2981 <div class="example"><p><code>
2985 <p>Setting <code>ScriptInterpreterSource Registry</code> will
2986 cause the Windows Registry tree <code>HKEY_CLASSES_ROOT</code> to be
2987 searched using the script file extension (e.g., <code>.pl</code>) as a
2988 search key. The command defined by the registry subkey
2989 <code>Shell\ExecCGI\Command</code> or, if it does not exist, by the subkey
2990 <code>Shell\Open\Command</code> is used to open the script file. If the
2991 registry keys cannot be found, Apache httpd falls back to the behavior of the
2992 <code>Script</code> option.</p>
2994 <div class="warning"><h3>Security</h3>
2995 <p>Be careful when using <code>ScriptInterpreterSource
2996 Registry</code> with <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories, because
2997 Apache httpd will try to execute <strong>every</strong> file within this
2998 directory. The <code>Registry</code> setting may cause undesired
2999 program calls on files which are typically not executed. For
3000 example, the default open command on <code>.htm</code> files on
3001 most Windows systems will execute Microsoft Internet Explorer, so
3002 any HTTP request for an <code>.htm</code> file existing within the
3003 script directory would start the browser in the background on the
3004 server. This is a good way to crash your system within a minute or
3008 <p>The option <code>Registry-Strict</code> which is new in Apache HTTP Server
3009 2.0 does the same thing as <code>Registry</code> but uses only the
3010 subkey <code>Shell\ExecCGI\Command</code>. The
3011 <code>ExecCGI</code> key is not a common one. It must be
3012 configured manually in the windows registry and hence prevents
3013 accidental program calls on your system.</p>
3016 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3017 <div class="directive-section"><h2><a name="SeeRequestTail" id="SeeRequestTail">SeeRequestTail</a> <a name="seerequesttail" id="seerequesttail">Directive</a></h2>
3018 <table class="directive">
3019 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine if mod_status displays the first 63 characters
3020 of a request or the last 63, assuming the request itself is greater than
3022 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SeeRequestTail On|Off</code></td></tr>
3023 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SeeRequestTail Off</code></td></tr>
3024 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3025 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3026 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3027 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.2.7 and later.</td></tr>
3029 <p>mod_status with <code>ExtendedStatus On</code>
3030 displays the actual request being handled.
3031 For historical purposes, only 63 characters of the request
3032 are actually stored for display purposes. This directive
3033 controls whether the 1st 63 characters are stored (the previous
3034 behavior and the default) or if the last 63 characters are. This
3035 is only applicable, of course, if the length of the request is
3036 64 characters or greater.</p>
3038 <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:
3041 <table class="bordered">
3043 <th>Off (default)</th>
3044 <td>GET /disk1/storage/apache/htdocs/images/imagestore1/food/apples</td>
3048 <td>orage/apache/htdocs/images/imagestore1/food/apples.jpg HTTP/1.1</td>
3054 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3055 <div class="directive-section"><h2><a name="ServerAdmin" id="ServerAdmin">ServerAdmin</a> <a name="serveradmin" id="serveradmin">Directive</a></h2>
3056 <table class="directive">
3057 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Email address that the server includes in error
3058 messages sent to the client</td></tr>
3059 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAdmin <var>email-address</var>|<var>URL</var></code></td></tr>
3060 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3061 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3062 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3064 <p>The <code class="directive">ServerAdmin</code> sets the contact address
3065 that the server includes in any error messages it returns to the
3066 client. If the <code>httpd</code> doesn't recognize the supplied argument
3068 assumes, that it's an <var>email-address</var> and prepends it with
3069 <code>mailto:</code> in hyperlink targets. However, it's recommended to
3070 actually use an email address, since there are a lot of CGI scripts that
3071 make that assumption. If you want to use an URL, it should point to another
3072 server under your control. Otherwise users may not be able to contact you in
3075 <p>It may be worth setting up a dedicated address for this, e.g.</p>
3077 <div class="example"><p><code>
3078 ServerAdmin www-admin@foo.example.com
3080 <p>as users do not always mention that they are talking about the
3084 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3085 <div class="directive-section"><h2><a name="ServerAlias" id="ServerAlias">ServerAlias</a> <a name="serveralias" id="serveralias">Directive</a></h2>
3086 <table class="directive">
3087 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Alternate names for a host used when matching requests
3088 to name-virtual hosts</td></tr>
3089 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAlias <var>hostname</var> [<var>hostname</var>] ...</code></td></tr>
3090 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
3091 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3092 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3094 <p>The <code class="directive">ServerAlias</code> directive sets the
3095 alternate names for a host, for use with <a href="../vhosts/name-based.html">name-based virtual hosts</a>. The
3096 <code class="directive">ServerAlias</code> may include wildcards, if appropriate.</p>
3098 <div class="example"><p><code>
3099 <VirtualHost *:80><br />
3100 ServerName server.domain.com<br />
3101 ServerAlias server server2.domain.com server2<br />
3102 ServerAlias *.example.com<br />
3104 </VirtualHost>
3109 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
3112 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3113 <div class="directive-section"><h2><a name="ServerName" id="ServerName">ServerName</a> <a name="servername" id="servername">Directive</a></h2>
3114 <table class="directive">
3115 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Hostname and port that the server uses to identify
3117 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerName [<var>scheme</var>://]<var>fully-qualified-domain-name</var>[:<var>port</var>]</code></td></tr>
3118 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3119 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3120 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3122 <p>The <code class="directive">ServerName</code> directive sets the
3123 request scheme, hostname and
3124 port that the server uses to identify itself. This is used when
3125 creating redirection URLs. For example, if the name of the
3126 machine hosting the web server is <code>simple.example.com</code>,
3127 but the machine also has the DNS alias <code>www.example.com</code>
3128 and you wish the web server to be so identified, the following
3129 directive should be used:</p>
3131 <div class="example"><p><code>
3132 ServerName www.example.com:80
3135 <p>The <code class="directive">ServerName</code> directive
3136 may appear anywhere within the definition of a server. However,
3137 each appearance overrides the previous appearance (within that
3140 <p>If no <code class="directive">ServerName</code> is specified, then the
3141 server attempts to deduce the hostname by performing a reverse
3142 lookup on the IP address. If no port is specified in the
3143 <code class="directive">ServerName</code>, then the server will use the
3144 port from the incoming request. For optimal reliability and
3145 predictability, you should specify an explicit hostname and port
3146 using the <code class="directive">ServerName</code> directive.</p>
3148 <p>If you are using <a href="../vhosts/name-based.html">name-based virtual hosts</a>,
3149 the <code class="directive">ServerName</code> inside a
3150 <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
3151 section specifies what hostname must appear in the request's
3152 <code>Host:</code> header to match this virtual host.</p>
3155 <p>Sometimes, the server runs behind a device that processes SSL,
3156 such as a reverse proxy, load balancer or SSL offload
3157 appliance. When this is the case, specify the
3158 <code>https://</code> scheme and the port number to which the
3159 clients connect in the <code class="directive">ServerName</code> directive
3160 to make sure that the server generates the correct
3161 self-referential URLs.
3164 <p>See the description of the
3165 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> and
3166 <code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code> directives for
3167 settings which determine whether self-referential URLs (e.g., by the
3168 <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> module) will refer to the
3169 specified port, or to the port number given in the client's request.
3175 <li><a href="../dns-caveats.html">Issues Regarding DNS and
3176 Apache HTTP Server</a></li>
3177 <li><a href="../vhosts/">Apache HTTP Server virtual host
3178 documentation</a></li>
3179 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
3180 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
3181 <li><code class="directive"><a href="#namevirtualhost">NameVirtualHost</a></code></li>
3182 <li><code class="directive"><a href="#serveralias">ServerAlias</a></code></li>
3185 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3186 <div class="directive-section"><h2><a name="ServerPath" id="ServerPath">ServerPath</a> <a name="serverpath" id="serverpath">Directive</a></h2>
3187 <table class="directive">
3188 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Legacy URL pathname for a name-based virtual host that
3189 is accessed by an incompatible browser</td></tr>
3190 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerPath <var>URL-path</var></code></td></tr>
3191 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
3192 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3193 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3195 <p>The <code class="directive">ServerPath</code> directive sets the legacy
3196 URL pathname for a host, for use with <a href="../vhosts/">name-based virtual hosts</a>.</p>
3200 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
3203 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3204 <div class="directive-section"><h2><a name="ServerRoot" id="ServerRoot">ServerRoot</a> <a name="serverroot" id="serverroot">Directive</a></h2>
3205 <table class="directive">
3206 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server installation</td></tr>
3207 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerRoot <var>directory-path</var></code></td></tr>
3208 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerRoot /usr/local/apache</code></td></tr>
3209 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3210 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3211 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3213 <p>The <code class="directive">ServerRoot</code> directive sets the
3214 directory in which the server lives. Typically it will contain the
3215 subdirectories <code>conf/</code> and <code>logs/</code>. Relative
3216 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
3217 relative to this directory.</p>
3219 <div class="example"><h3>Example</h3><p><code>
3220 ServerRoot /home/httpd
3226 <li><a href="../invoking.html">the <code>-d</code>
3227 option to <code>httpd</code></a></li>
3228 <li><a href="../misc/security_tips.html#serverroot">the
3229 security tips</a> for information on how to properly set
3230 permissions on the <code class="directive">ServerRoot</code></li>
3233 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3234 <div class="directive-section"><h2><a name="ServerSignature" id="ServerSignature">ServerSignature</a> <a name="serversignature" id="serversignature">Directive</a></h2>
3235 <table class="directive">
3236 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the footer on server-generated documents</td></tr>
3237 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerSignature On|Off|EMail</code></td></tr>
3238 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerSignature Off</code></td></tr>
3239 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3240 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3241 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3242 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3244 <p>The <code class="directive">ServerSignature</code> directive allows the
3245 configuration of a trailing footer line under server-generated
3246 documents (error messages, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> ftp directory
3247 listings, <code class="module"><a href="../mod/mod_info.html">mod_info</a></code> output, ...). The reason why you
3248 would want to enable such a footer line is that in a chain of proxies,
3249 the user often has no possibility to tell which of the chained servers
3250 actually produced a returned error message.</p>
3252 <p>The <code>Off</code>
3253 setting, which is the default, suppresses the footer line (and is
3254 therefore compatible with the behavior of Apache-1.2 and
3255 below). The <code>On</code> setting simply adds a line with the
3256 server version number and <code class="directive"><a href="#servername">ServerName</a></code> of the serving virtual host,
3257 and the <code>EMail</code> setting additionally creates a
3258 "mailto:" reference to the <code class="directive"><a href="#serveradmin">ServerAdmin</a></code> of the referenced
3261 <p>After version 2.0.44, the details of the server version number
3262 presented are controlled by the <code class="directive"><a href="#servertokens">ServerTokens</a></code> directive.</p>
3266 <li><code class="directive"><a href="#servertokens">ServerTokens</a></code></li>
3269 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3270 <div class="directive-section"><h2><a name="ServerTokens" id="ServerTokens">ServerTokens</a> <a name="servertokens" id="servertokens">Directive</a></h2>
3271 <table class="directive">
3272 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the <code>Server</code> HTTP response
3274 <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>
3275 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerTokens Full</code></td></tr>
3276 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3277 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3278 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3280 <p>This directive controls whether <code>Server</code> response
3281 header field which is sent back to clients includes a
3282 description of the generic OS-type of the server as well as
3283 information about compiled-in modules.</p>
3286 <dt><code>ServerTokens Full</code> (or not specified)</dt>
3288 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.1
3289 (Unix) PHP/4.2.2 MyMod/1.2</code></dd>
3291 <dt><code>ServerTokens Prod[uctOnly]</code></dt>
3293 <dd>Server sends (<em>e.g.</em>): <code>Server:
3296 <dt><code>ServerTokens Major</code></dt>
3298 <dd>Server sends (<em>e.g.</em>): <code>Server:
3299 Apache/2</code></dd>
3301 <dt><code>ServerTokens Minor</code></dt>
3303 <dd>Server sends (<em>e.g.</em>): <code>Server:
3304 Apache/2.4</code></dd>
3306 <dt><code>ServerTokens Min[imal]</code></dt>
3308 <dd>Server sends (<em>e.g.</em>): <code>Server:
3309 Apache/2.4.1</code></dd>
3311 <dt><code>ServerTokens OS</code></dt>
3313 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.1
3318 <p>This setting applies to the entire server, and cannot be
3319 enabled or disabled on a virtualhost-by-virtualhost basis.</p>
3321 <p>After version 2.0.44, this directive also controls the
3322 information presented by the <code class="directive"><a href="#serversignature">ServerSignature</a></code> directive.</p>
3324 <div class="note">Setting <code class="directive">ServerTokens</code> to less than
3325 <code>minimal</code> is not recommended because it makes it more
3326 difficult to debug interoperational problems. Also note that
3327 disabling the Server: header does nothing at all to make your
3328 server more secure; the idea of "security through obscurity"
3329 is a myth and leads to a false sense of safety.</div>
3334 <li><code class="directive"><a href="#serversignature">ServerSignature</a></code></li>
3337 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3338 <div class="directive-section"><h2><a name="SetHandler" id="SetHandler">SetHandler</a> <a name="sethandler" id="sethandler">Directive</a></h2>
3339 <table class="directive">
3340 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be processed by a
3342 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetHandler <var>handler-name</var>|None</code></td></tr>
3343 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3344 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3345 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3346 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3347 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Moved into the core in Apache httpd 2.0</td></tr>
3349 <p>When placed into an <code>.htaccess</code> file or a
3350 <code class="directive"><a href="#directory"><Directory></a></code> or
3351 <code class="directive"><a href="#location"><Location></a></code>
3352 section, this directive forces all matching files to be parsed
3353 through the <a href="../handler.html">handler</a> given by
3354 <var>handler-name</var>. For example, if you had a directory you
3355 wanted to be parsed entirely as imagemap rule files, regardless
3356 of extension, you might put the following into an
3357 <code>.htaccess</code> file in that directory:</p>
3359 <div class="example"><p><code>
3360 SetHandler imap-file
3363 <p>Another example: if you wanted to have the server display a
3364 status report whenever a URL of
3365 <code>http://servername/status</code> was called, you might put
3366 the following into <code>httpd.conf</code>:</p>
3368 <div class="example"><p><code>
3369 <Location /status><br />
3370 <span class="indent">
3371 SetHandler server-status<br />
3376 <p>You can override an earlier defined <code class="directive">SetHandler</code>
3377 directive by using the value <code>None</code>.</p>
3378 <p><strong>Note:</strong> because SetHandler overrides default handlers,
3379 normal behaviour such as handling of URLs ending in a slash (/) as
3380 directories or index files is suppressed.</p>
3384 <li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li>
3387 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3388 <div class="directive-section"><h2><a name="SetInputFilter" id="SetInputFilter">SetInputFilter</a> <a name="setinputfilter" id="setinputfilter">Directive</a></h2>
3389 <table class="directive">
3390 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process client requests and POST
3392 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetInputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
3393 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3394 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3395 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3396 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3398 <p>The <code class="directive">SetInputFilter</code> directive sets the
3399 filter or filters which will process client requests and POST
3400 input when they are received by the server. This is in addition to
3401 any filters defined elsewhere, including the
3402 <code class="directive"><a href="../mod/mod_mime.html#addinputfilter">AddInputFilter</a></code>
3405 <p>If more than one filter is specified, they must be separated
3406 by semicolons in the order in which they should process the
3411 <li><a href="../filter.html">Filters</a> documentation</li>
3414 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3415 <div class="directive-section"><h2><a name="SetOutputFilter" id="SetOutputFilter">SetOutputFilter</a> <a name="setoutputfilter" id="setoutputfilter">Directive</a></h2>
3416 <table class="directive">
3417 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process responses from the
3419 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetOutputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
3420 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3421 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3422 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3423 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3425 <p>The <code class="directive">SetOutputFilter</code> directive sets the filters
3426 which will process responses from the server before they are
3427 sent to the client. This is in addition to any filters defined
3428 elsewhere, including the
3429 <code class="directive"><a href="../mod/mod_mime.html#addoutputfilter">AddOutputFilter</a></code>
3432 <p>For example, the following configuration will process all files
3433 in the <code>/www/data/</code> directory for server-side
3436 <div class="example"><p><code>
3437 <Directory /www/data/><br />
3438 <span class="indent">
3439 SetOutputFilter INCLUDES<br />
3444 <p>If more than one filter is specified, they must be separated
3445 by semicolons in the order in which they should process the
3450 <li><a href="../filter.html">Filters</a> documentation</li>
3453 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3454 <div class="directive-section"><h2><a name="TimeOut" id="TimeOut">TimeOut</a> <a name="timeout" id="timeout">Directive</a></h2>
3455 <table class="directive">
3456 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for
3457 certain events before failing a request</td></tr>
3458 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TimeOut <var>seconds</var></code></td></tr>
3459 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TimeOut 300</code></td></tr>
3460 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3461 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3462 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3464 <p>The <code class="directive">TimeOut</code> directive defines the length
3465 of time Apache httpd will wait for I/O in various circumstances:</p>
3468 <li>When reading data from the client, the length of time to
3469 wait for a TCP packet to arrive if the read buffer is
3472 <li>When writing data to the client, the length of time to wait
3473 for an acknowledgement of a packet if the send buffer is
3476 <li>In <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>, the length of time to wait for
3477 output from a CGI script.</li>
3479 <li>In <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>, the length of time to
3480 wait for output from a filtering process.</li>
3482 <li>In <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, the default timeout value if
3483 <code class="directive"><a href="../mod/mod_proxy.html#proxytimeout">ProxyTimeout</a></code> is not
3489 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3490 <div class="directive-section"><h2><a name="TraceEnable" id="TraceEnable">TraceEnable</a> <a name="traceenable" id="traceenable">Directive</a></h2>
3491 <table class="directive">
3492 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines the behaviour on <code>TRACE</code>
3494 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TraceEnable <var>[on|off|extended]</var></code></td></tr>
3495 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TraceEnable on</code></td></tr>
3496 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3497 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3498 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3499 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 1.3.34, 2.0.55 and later</td></tr>
3501 <p>This directive overrides the behavior of <code>TRACE</code> for both
3502 the core server and <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. The default
3503 <code>TraceEnable on</code> permits <code>TRACE</code> requests per
3504 RFC 2616, which disallows any request body to accompany the request.
3505 <code>TraceEnable off</code> causes the core server and
3506 <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> to return a <code>405</code> (Method not
3507 allowed) error to the client.</p>
3509 <p>Finally, for testing and diagnostic purposes only, request
3510 bodies may be allowed using the non-compliant <code>TraceEnable
3511 extended</code> directive. The core (as an origin server) will
3512 restrict the request body to 64k (plus 8k for chunk headers if
3513 <code>Transfer-Encoding: chunked</code> is used). The core will
3514 reflect the full headers and all chunk headers with the response
3515 body. As a proxy server, the request body is not restricted to 64k.</p>
3518 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3519 <div class="directive-section"><h2><a name="UnDefine" id="UnDefine">UnDefine</a> <a name="undefine" id="undefine">Directive</a></h2>
3520 <table class="directive">
3521 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Undefine the existence of a variable</td></tr>
3522 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UnDefine <var>parameter-name</var></code></td></tr>
3523 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3524 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3525 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3527 <p>Undoes the effect of a <code class="directive"><a href="#define">Define</a></code> or
3528 of passing a <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</p>
3529 <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
3530 <code>-D</code> arguments in any startup scripts.</p>
3533 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3534 <div class="directive-section"><h2><a name="UseCanonicalName" id="UseCanonicalName">UseCanonicalName</a> <a name="usecanonicalname" id="usecanonicalname">Directive</a></h2>
3535 <table class="directive">
3536 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own name and
3538 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalName On|Off|DNS</code></td></tr>
3539 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalName Off</code></td></tr>
3540 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3541 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3542 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3544 <p>In many situations Apache httpd must construct a <em>self-referential</em>
3545 URL -- that is, a URL that refers back to the same server. With
3546 <code>UseCanonicalName On</code> Apache httpd will use the hostname and port
3547 specified in the <code class="directive"><a href="#servername">ServerName</a></code>
3548 directive to construct the canonical name for the server. This name
3549 is used in all self-referential URLs, and for the values of
3550 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in CGIs.</p>
3552 <p>With <code>UseCanonicalName Off</code> Apache httpd will form
3553 self-referential URLs using the hostname and port supplied by
3554 the client if any are supplied (otherwise it will use the
3555 canonical name, as defined above). These values are the same
3556 that are used to implement <a href="../vhosts/name-based.html">name-based virtual hosts</a>,
3557 and are available with the same clients. The CGI variables
3558 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
3559 constructed from the client supplied values as well.</p>
3561 <p>An example where this may be useful is on an intranet server
3562 where you have users connecting to the machine using short
3563 names such as <code>www</code>. You'll notice that if the users
3564 type a shortname, and a URL which is a directory, such as
3565 <code>http://www/splat</code>, <em>without the trailing
3566 slash</em> then Apache httpd will redirect them to
3567 <code>http://www.domain.com/splat/</code>. If you have
3568 authentication enabled, this will cause the user to have to
3569 authenticate twice (once for <code>www</code> and once again
3570 for <code>www.domain.com</code> -- see <a href="http://httpd.apache.org/docs/misc/FAQ.html#prompted-twice">the
3571 FAQ on this subject for more information</a>). But if
3572 <code class="directive">UseCanonicalName</code> is set <code>Off</code>, then
3573 Apache httpd will redirect to <code>http://www/splat/</code>.</p>
3575 <p>There is a third option, <code>UseCanonicalName DNS</code>,
3576 which is intended for use with mass IP-based virtual hosting to
3577 support ancient clients that do not provide a
3578 <code>Host:</code> header. With this option Apache httpd does a
3579 reverse DNS lookup on the server IP address that the client
3580 connected to in order to work out self-referential URLs.</p>
3582 <div class="warning"><h3>Warning</h3>
3583 <p>If CGIs make assumptions about the values of <code>SERVER_NAME</code>
3584 they may be broken by this option. The client is essentially free
3585 to give whatever value they want as a hostname. But if the CGI is
3586 only using <code>SERVER_NAME</code> to construct self-referential URLs
3587 then it should be just fine.</p>
3592 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
3593 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
3594 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
3597 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3598 <div class="directive-section"><h2><a name="UseCanonicalPhysicalPort" id="UseCanonicalPhysicalPort">UseCanonicalPhysicalPort</a> <a name="usecanonicalphysicalport" id="usecanonicalphysicalport">Directive</a></h2>
3599 <table class="directive">
3600 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own name and
3602 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalPhysicalPort On|Off</code></td></tr>
3603 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalPhysicalPort Off</code></td></tr>
3604 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3605 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3606 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3608 <p>In many situations Apache httpd must construct a <em>self-referential</em>
3609 URL -- that is, a URL that refers back to the same server. With
3610 <code>UseCanonicalPhysicalPort On</code> Apache httpd will, when
3611 constructing the canonical port for the server to honor
3612 the <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> directive,
3613 provide the actual physical port number being used by this request
3614 as a potential port. With <code>UseCanonicalPhysicalPort Off</code>
3615 Apache httpd will not ever use the actual physical port number, instead
3616 relying on all configured information to construct a valid port number.</p>
3618 <div class="note"><h3>Note</h3>
3619 <p>The ordering of when the physical port is used is as follows:<br /><br />
3620 <code>UseCanonicalName On</code></p>
3622 <li>Port provided in <code>Servername</code></li>
3623 <li>Physical port</li>
3624 <li>Default port</li>
3626 <code>UseCanonicalName Off | DNS</code>
3628 <li>Parsed port from <code>Host:</code> header</li>
3629 <li>Physical port</li>
3630 <li>Port provided in <code>Servername</code></li>
3631 <li>Default port</li>
3634 <p>With <code>UseCanonicalPhysicalPort Off</code>, the
3635 physical ports are removed from the ordering.</p>
3641 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
3642 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
3643 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
3646 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3647 <div class="directive-section"><h2><a name="VirtualHost" id="VirtualHost"><VirtualHost></a> <a name="virtualhost" id="virtualhost">Directive</a></h2>
3648 <table class="directive">
3649 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only to a specific
3650 hostname or IP address</td></tr>
3651 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><VirtualHost
3652 <var>addr</var>[:<var>port</var>] [<var>addr</var>[:<var>port</var>]]
3653 ...> ... </VirtualHost></code></td></tr>
3654 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3655 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3656 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3658 <p><code class="directive"><VirtualHost></code> and
3659 <code></VirtualHost></code> are used to enclose a group of
3660 directives that will apply only to a particular virtual host. Any
3661 directive that is allowed in a virtual host context may be
3662 used. When the server receives a request for a document on a
3663 particular virtual host, it uses the configuration directives
3664 enclosed in the <code class="directive"><VirtualHost></code>
3665 section. <var>Addr</var> can be:</p>
3668 <li>The IP address of the virtual host;</li>
3670 <li>A fully qualified domain name for the IP address of the
3671 virtual host (not recommended);</li>
3673 <li>The character <code>*</code>, which is used only in combination with
3674 <code>NameVirtualHost *</code> to match all IP addresses; or</li>
3676 <li>The string <code>_default_</code>, which is used only
3677 with IP virtual hosting to catch unmatched IP addresses.</li>
3680 <div class="example"><h3>Example</h3><p><code>
3681 <VirtualHost 10.1.2.3><br />
3682 <span class="indent">
3683 ServerAdmin webmaster@host.example.com<br />
3684 DocumentRoot /www/docs/host.example.com<br />
3685 ServerName host.example.com<br />
3686 ErrorLog logs/host.example.com-error_log<br />
3687 TransferLog logs/host.example.com-access_log<br />
3689 </VirtualHost>
3693 <p>IPv6 addresses must be specified in square brackets because
3694 the optional port number could not be determined otherwise. An
3695 IPv6 example is shown below:</p>
3697 <div class="example"><p><code>
3698 <VirtualHost [2001:db8::a00:20ff:fea7:ccea]><br />
3699 <span class="indent">
3700 ServerAdmin webmaster@host.example.com<br />
3701 DocumentRoot /www/docs/host.example.com<br />
3702 ServerName host.example.com<br />
3703 ErrorLog logs/host.example.com-error_log<br />
3704 TransferLog logs/host.example.com-access_log<br />
3706 </VirtualHost>
3709 <p>Each Virtual Host must correspond to a different IP address,
3710 different port number or a different host name for the server,
3711 in the former case the server machine must be configured to
3712 accept IP packets for multiple addresses. (If the machine does
3713 not have multiple network interfaces, then this can be
3714 accomplished with the <code>ifconfig alias</code> command -- if
3715 your OS supports it).</p>
3717 <div class="note"><h3>Note</h3>
3718 <p>The use of <code class="directive"><VirtualHost></code> does
3719 <strong>not</strong> affect what addresses Apache httpd listens on. You
3720 may need to ensure that Apache httpd is listening on the correct addresses
3721 using <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>.</p>
3724 <p>When using IP-based virtual hosting, the special name
3725 <code>_default_</code> can be specified in
3726 which case this virtual host will match any IP address that is
3727 not explicitly listed in another virtual host. In the absence
3728 of any <code>_default_</code> virtual host the "main" server config,
3729 consisting of all those definitions outside any VirtualHost
3730 section, is used when no IP-match occurs.</p>
3732 <p>You can specify a <code>:port</code> to change the port that is
3733 matched. If unspecified then it defaults to the same port as the
3734 most recent <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>
3735 statement of the main server. You may also specify <code>:*</code>
3736 to match all ports on that address. (This is recommended when used
3737 with <code>_default_</code>.)</p>
3739 <p>A <code class="directive"><a href="#servername">ServerName</a></code> should be
3740 specified inside each <code class="directive"><VirtualHost></code> block. If it is absent, the
3741 <code class="directive"><a href="#servername">ServerName</a></code> from the "main"
3742 server configuration will be inherited.</p>
3744 <p>If no matching virtual host is found, then the first listed
3745 virtual host that matches the IP address will be used. As a
3746 consequence, the first listed virtual host is the default virtual
3749 <div class="warning"><h3>Security</h3>
3750 <p>See the <a href="../misc/security_tips.html">security tips</a>
3751 document for details on why your security could be compromised if the
3752 directory where log files are stored is writable by anyone other
3753 than the user that starts the server.</p>
3758 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
3759 <li><a href="../dns-caveats.html">Issues Regarding DNS and
3760 Apache HTTP Server</a></li>
3761 <li><a href="../bind.html">Setting
3762 which addresses and ports Apache HTTP Server uses</a></li>
3763 <li><a href="../sections.html">How <Directory>, <Location>
3764 and <Files> sections work</a> for an explanation of how these
3765 different sections are combined when a request is received</li>
3769 <div class="bottomlang">
3770 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
3771 <a href="../en/mod/core.html" title="English"> en </a> |
3772 <a href="../fr/mod/core.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
3773 <a href="../ja/mod/core.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
3774 <a href="../tr/mod/core.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
3775 </div><div id="footer">
3776 <p class="apache">Copyright 2010 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>
3777 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div>