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10 The ASF licenses this file to You under the Apache License, Version 2.0
11 (the "License"); you may not use this file except in compliance with
12 the License. You may obtain a copy of the License at
14 http://www.apache.org/licenses/LICENSE-2.0
16 Unless required by applicable law or agreed to in writing, software
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18 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19 See the License for the specific language governing permissions and
20 limitations under the License.
23 <modulesynopsis metafile="core.xml.meta">
26 <description>Core Apache HTTP Server features that are always
27 available</description>
31 <name>AcceptFilter</name>
32 <description>Configures optimizations for a Protocol's Listener Sockets</description>
33 <syntax>AcceptFilter <var>protocol</var> <var>accept_filter</var></syntax>
34 <contextlist><context>server config</context></contextlist>
35 <compatibility>Available in Apache 2.1.5 and later</compatibility>
38 <p>This directive enables operating system specific optimizations for a
39 listening socket by the Protocol type. The basic premise is for the
40 kernel to not send a socket to the server process until either data
41 is received or an entire HTTP Request is buffered. Only
42 <a href="http://www.freebsd.org/cgi/man.cgi?query=accept_filter&sektion=9">
43 FreeBSD's Accept Filters</a> and Linux's more primitive
44 <code>TCP_DEFER_ACCEPT</code> are currently supported.</p>
46 <p>The default values on FreeBSD are:</p>
48 AcceptFilter http httpready <br/>
49 AcceptFilter https dataready
52 <p>The <code>httpready</code> accept filter buffers entire HTTP requests at
53 the kernel level. Once an entire request is received, the kernel then
54 sends it to the server. See the
55 <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_http&sektion=9">
56 accf_http(9)</a> man page for more details. Since HTTPS requests are
57 encrypted only the <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_data&sektion=9">
58 accf_data(9)</a> filter is used.</p>
60 <p>The default values on Linux are:</p>
62 AcceptFilter http data <br/>
63 AcceptFilter https data
66 <p>Linux's <code>TCP_DEFER_ACCEPT</code> does not support buffering http
67 requests. Any value besides <code>none</code> will enable
68 <code>TCP_DEFER_ACCEPT</code> on that listener. For more details
70 <a href="http://homepages.cwi.nl/~aeb/linux/man2html/man7/tcp.7.html">
71 tcp(7)</a> man page.</p>
73 <p>Using <code>none</code> for an argument will disable any accept filters
74 for that protocol. This is useful for protocols that require a server
75 send data first, such as <code>nntp</code>:</p>
76 <example>AcceptFilter nntp none</example>
82 <name>AcceptPathInfo</name>
83 <description>Resources accept trailing pathname information</description>
84 <syntax>AcceptPathInfo On|Off|Default</syntax>
85 <default>AcceptPathInfo Default</default>
86 <contextlist><context>server config</context>
87 <context>virtual host</context><context>directory</context>
88 <context>.htaccess</context></contextlist>
89 <override>FileInfo</override>
90 <compatibility>Available in Apache 2.0.30 and later</compatibility>
94 <p>This directive controls whether requests that contain trailing
95 pathname information that follows an actual filename (or
96 non-existent file in an existing directory) will be accepted or
97 rejected. The trailing pathname information can be made
98 available to scripts in the <code>PATH_INFO</code> environment
101 <p>For example, assume the location <code>/test/</code> points to
102 a directory that contains only the single file
103 <code>here.html</code>. Then requests for
104 <code>/test/here.html/more</code> and
105 <code>/test/nothere.html/more</code> both collect
106 <code>/more</code> as <code>PATH_INFO</code>.</p>
108 <p>The three possible arguments for the
109 <directive>AcceptPathInfo</directive> directive are:</p>
111 <dt><code>Off</code></dt><dd>A request will only be accepted if it
112 maps to a literal path that exists. Therefore a request with
113 trailing pathname information after the true filename such as
114 <code>/test/here.html/more</code> in the above example will return
115 a 404 NOT FOUND error.</dd>
117 <dt><code>On</code></dt><dd>A request will be accepted if a
118 leading path component maps to a file that exists. The above
119 example <code>/test/here.html/more</code> will be accepted if
120 <code>/test/here.html</code> maps to a valid file.</dd>
122 <dt><code>Default</code></dt><dd>The treatment of requests with
123 trailing pathname information is determined by the <a
124 href="../handler.html">handler</a> responsible for the request.
125 The core handler for normal files defaults to rejecting
126 <code>PATH_INFO</code> requests. Handlers that serve scripts, such as <a
127 href="mod_cgi.html">cgi-script</a> and <a
128 href="mod_isapi.html">isapi-handler</a>, generally accept
129 <code>PATH_INFO</code> by default.</dd>
132 <p>The primary purpose of the <code>AcceptPathInfo</code>
133 directive is to allow you to override the handler's choice of
134 accepting or rejecting <code>PATH_INFO</code>. This override is required,
135 for example, when you use a <a href="../filter.html">filter</a>, such
136 as <a href="mod_include.html">INCLUDES</a>, to generate content
137 based on <code>PATH_INFO</code>. The core handler would usually reject
138 the request, so you can use the following configuration to enable
142 <Files "mypaths.shtml"><br />
144 Options +Includes<br />
145 SetOutputFilter INCLUDES<br />
146 AcceptPathInfo On<br />
155 <name>AccessFileName</name>
156 <description>Name of the distributed configuration file</description>
157 <syntax>AccessFileName <var>filename</var> [<var>filename</var>] ...</syntax>
158 <default>AccessFileName .htaccess</default>
159 <contextlist><context>server config</context><context>virtual host</context>
163 <p>While processing a request the server looks for
164 the first existing configuration file from this list of names in
165 every directory of the path to the document, if distributed
166 configuration files are <a href="#allowoverride">enabled for that
167 directory</a>. For example:</p>
173 <p>before returning the document
174 <code>/usr/local/web/index.html</code>, the server will read
175 <code>/.acl</code>, <code>/usr/.acl</code>,
176 <code>/usr/local/.acl</code> and <code>/usr/local/web/.acl</code>
177 for directives, unless they have been disabled with</p>
180 <Directory /><br />
182 AllowOverride None<br />
187 <seealso><directive module="core">AllowOverride</directive></seealso>
188 <seealso><a href="../configuring.html">Configuration Files</a></seealso>
189 <seealso><a href="../howto/htaccess.html">.htaccess Files</a></seealso>
193 <name>AddDefaultCharset</name>
194 <description>Default charset parameter to be added when a response
195 content-type is <code>text/plain</code> or <code>text/html</code></description>
196 <syntax>AddDefaultCharset On|Off|<var>charset</var></syntax>
197 <default>AddDefaultCharset Off</default>
198 <contextlist><context>server config</context>
199 <context>virtual host</context><context>directory</context>
200 <context>.htaccess</context></contextlist>
201 <override>FileInfo</override>
204 <p>This directive specifies a default value for the media type
205 charset parameter (the name of a character encoding) to be added
206 to a response if and only if the response's content-type is either
207 <code>text/plain</code> or <code>text/html</code>. This should override
208 any charset specified in the body of the response via a <code>META</code>
209 element, though the exact behavior is often dependent on the user's client
210 configuration. A setting of <code>AddDefaultCharset Off</code>
211 disables this functionality. <code>AddDefaultCharset On</code> enables
212 a default charset of <code>iso-8859-1</code>. Any other value is assumed
213 to be the <var>charset</var> to be used, which should be one of the
214 <a href="http://www.iana.org/assignments/character-sets">IANA registered
215 charset values</a> for use in MIME media types.
219 AddDefaultCharset utf-8
222 <p><directive>AddDefaultCharset</directive> should only be used when all
223 of the text resources to which it applies are known to be in that
224 character encoding and it is too inconvenient to label their charset
225 individually. One such example is to add the charset parameter
226 to resources containing generated content, such as legacy CGI
227 scripts, that might be vulnerable to cross-site scripting attacks
228 due to user-provided data being included in the output. Note, however,
229 that a better solution is to just fix (or delete) those scripts, since
230 setting a default charset does not protect users that have enabled
231 the "auto-detect character encoding" feature on their browser.</p>
233 <seealso><directive module="mod_mime">AddCharset</directive></seealso>
237 <name>AddOutputFilterByType</name>
238 <description>assigns an output filter to a particular MIME-type</description>
239 <syntax>AddOutputFilterByType <var>filter</var>[;<var>filter</var>...]
240 <var>MIME-type</var> [<var>MIME-type</var>] ...</syntax>
241 <contextlist><context>server config</context>
242 <context>virtual host</context><context>directory</context>
243 <context>.htaccess</context></contextlist>
244 <override>FileInfo</override>
245 <compatibility>Available in Apache 2.0.33 and later; deprecated in Apache 2.1 and later</compatibility>
248 <p>This directive activates a particular output <a
249 href="../filter.html">filter</a> for a request depending on the
250 response <glossary>MIME-type</glossary>. Because of certain
251 problems discussed below, this directive is deprecated. The same
252 functionality is available using <module>mod_filter</module>.</p>
254 <p>The following example uses the <code>DEFLATE</code> filter, which
255 is provided by <module>mod_deflate</module>. It will compress all
256 output (either static or dynamic) which is labeled as
257 <code>text/html</code> or <code>text/plain</code> before it is sent
261 AddOutputFilterByType DEFLATE text/html text/plain
264 <p>If you want the content to be processed by more than one filter, their
265 names have to be separated by semicolons. It's also possible to use one
266 <directive>AddOutputFilterByType</directive> directive for each of
269 <p>The configuration below causes all script output labeled as
270 <code>text/html</code> to be processed at first by the
271 <code>INCLUDES</code> filter and then by the <code>DEFLATE</code>
275 <Location /cgi-bin/><br />
277 Options Includes<br />
278 AddOutputFilterByType INCLUDES;DEFLATE text/html<br />
283 <note type="warning"><title>Note</title>
284 <p>Enabling filters with <directive>AddOutputFilterByType</directive>
285 may fail partially or completely in some cases. For example, no
286 filters are applied if the <glossary>MIME-type</glossary> could not be determined and falls
287 back to the <directive module="core">DefaultType</directive> setting,
288 even if the <directive module="core">DefaultType</directive> is the
291 <p>However, if you want to make sure, that the filters will be
292 applied, assign the content type to a resource explicitly, for
293 example with <directive module="mod_mime">AddType</directive> or
294 <directive module="core">ForceType</directive>. Setting the
295 content type within a (non-nph) CGI script is also safe.</p>
300 <seealso><directive module="mod_mime">AddOutputFilter</directive></seealso>
301 <seealso><directive module="core">SetOutputFilter</directive></seealso>
302 <seealso><a href="../filter.html">filters</a></seealso>
306 <name>AllowEncodedSlashes</name>
307 <description>Determines whether encoded path separators in URLs are allowed to
308 be passed through</description>
309 <syntax>AllowEncodedSlashes On|Off</syntax>
310 <default>AllowEncodedSlashes Off</default>
311 <contextlist><context>server config</context><context>virtual host</context>
313 <compatibility>Available in Apache 2.0.46 and later</compatibility>
316 <p>The <directive>AllowEncodedSlashes</directive> directive allows URLs
317 which contain encoded path separators (<code>%2F</code> for <code>/</code>
318 and additionally <code>%5C</code> for <code>\</code> on according systems)
319 to be used. Normally such URLs are refused with a 404 (Not found) error.</p>
321 <p>Turning <directive>AllowEncodedSlashes</directive> <code>On</code> is
322 mostly useful when used in conjunction with <code>PATH_INFO</code>.</p>
324 <note><title>Note</title>
325 <p>Allowing encoded slashes does <em>not</em> imply <em>decoding</em>.
326 Occurrences of <code>%2F</code> or <code>%5C</code> (<em>only</em> on
327 according systems) will be left as such in the otherwise decoded URL
331 <seealso><directive module="core">AcceptPathInfo</directive></seealso>
335 <name>AllowOverride</name>
336 <description>Types of directives that are allowed in
337 <code>.htaccess</code> files</description>
338 <syntax>AllowOverride All|None|<var>directive-type</var>
339 [<var>directive-type</var>] ...</syntax>
340 <default>AllowOverride All</default>
341 <contextlist><context>directory</context></contextlist>
344 <p>When the server finds an <code>.htaccess</code> file (as
345 specified by <directive module="core">AccessFileName</directive>)
346 it needs to know which directives declared in that file can override
347 earlier configuration directives.</p>
349 <note><title>Only available in <Directory> sections</title>
350 <directive>AllowOverride</directive> is valid only in
351 <directive type="section" module="core">Directory</directive>
352 sections specified without regular expressions, not in <directive
353 type="section" module="core">Location</directive>, <directive
354 module="core" type="section">DirectoryMatch</directive> or
355 <directive type="section" module="core">Files</directive> sections.
358 <p>When this directive is set to <code>None</code>, then
359 <a href="#accessfilename">.htaccess</a> files are completely ignored.
360 In this case, the server will not even attempt to read
361 <code>.htaccess</code> files in the filesystem.</p>
363 <p>When this directive is set to <code>All</code>, then any
364 directive which has the .htaccess <a
365 href="directive-dict.html#Context">Context</a> is allowed in
366 <code>.htaccess</code> files.</p>
368 <p>The <var>directive-type</var> can be one of the following
369 groupings of directives.</p>
376 Allow use of the authorization directives (<directive
377 module="mod_authn_dbm">AuthDBMGroupFile</directive>,
378 <directive module="mod_authn_dbm">AuthDBMUserFile</directive>,
379 <directive module="mod_authz_groupfile">AuthGroupFile</directive>,
380 <directive module="mod_authn_core">AuthName</directive>,
381 <directive module="mod_authn_core">AuthType</directive>, <directive
382 module="mod_authn_file">AuthUserFile</directive>, <directive
383 module="mod_authz_core">Require</directive>, <em>etc.</em>).</dd>
388 Allow use of the directives controlling document types (<directive
389 module="core">DefaultType</directive>, <directive
390 module="core">ErrorDocument</directive>, <directive
391 module="core">ForceType</directive>, <directive
392 module="mod_negotiation">LanguagePriority</directive>,
393 <directive module="core">SetHandler</directive>, <directive
394 module="core">SetInputFilter</directive>, <directive
395 module="core">SetOutputFilter</directive>, and
396 <module>mod_mime</module> Add* and Remove*
397 directives, <em>etc.</em>), document meta data (<directive
398 module="mod_headers">Header</directive>, <directive
399 module="mod_headers">RequestHeader</directive>, <directive
400 module="mod_setenvif">SetEnvIf</directive>, <directive
401 module="mod_setenvif">SetEnvIfNoCase</directive>, <directive
402 module="mod_setenvif">BrowserMatch</directive>, <directive
403 module="mod_usertrack">CookieExpires</directive>, <directive
404 module="mod_usertrack">CookieDomain</directive>, <directive
405 module="mod_usertrack">CookieStyle</directive>, <directive
406 module="mod_usertrack">CookieTracking</directive>, <directive
407 module="mod_usertrack">CookieName</directive>),
408 <module>mod_rewrite</module> directives <directive
409 module="mod_rewrite">RewriteEngine</directive>, <directive
410 module="mod_rewrite">RewriteOptions</directive>, <directive
411 module="mod_rewrite">RewriteBase</directive>, <directive
412 module="mod_rewrite">RewriteCond</directive>, <directive
413 module="mod_rewrite">RewriteRule</directive>) and
414 <directive module="mod_actions">Action</directive> from
415 <module>mod_actions</module>.
421 Allow use of the directives controlling directory indexing
423 module="mod_autoindex">AddDescription</directive>,
424 <directive module="mod_autoindex">AddIcon</directive>, <directive
425 module="mod_autoindex">AddIconByEncoding</directive>,
426 <directive module="mod_autoindex">AddIconByType</directive>,
427 <directive module="mod_autoindex">DefaultIcon</directive>, <directive
428 module="mod_dir">DirectoryIndex</directive>, <directive
429 module="mod_autoindex">FancyIndexing</directive>, <directive
430 module="mod_autoindex">HeaderName</directive>, <directive
431 module="mod_autoindex">IndexIgnore</directive>, <directive
432 module="mod_autoindex">IndexOptions</directive>, <directive
433 module="mod_autoindex">ReadmeName</directive>,
439 Allow use of the directives controlling host access (<directive
440 module="mod_authz_host">Allow</directive>, <directive
441 module="mod_authz_host">Deny</directive> and <directive
442 module="mod_authz_host">Order</directive>).</dd>
444 <dt>Options[=<var>Option</var>,...]</dt>
447 Allow use of the directives controlling specific directory
448 features (<directive module="core">Options</directive> and
449 <directive module="mod_include">XBitHack</directive>).
450 An equal sign may be given followed by a comma (but no spaces)
451 separated lists of options that may be set using the <directive
452 module="core">Options</directive> command.</dd>
458 AllowOverride AuthConfig Indexes
461 <p>In the example above all directives that are neither in the group
462 <code>AuthConfig</code> nor <code>Indexes</code> cause an internal
466 <seealso><directive module="core">AccessFileName</directive></seealso>
467 <seealso><a href="../configuring.html">Configuration Files</a></seealso>
468 <seealso><a href="../howto/htaccess.html">.htaccess Files</a></seealso>
472 <name>CGIMapExtension</name>
473 <description>Technique for locating the interpreter for CGI
474 scripts</description>
475 <syntax>CGIMapExtension <var>cgi-path</var> <var>.extension</var></syntax>
476 <contextlist><context>directory</context><context>.htaccess</context>
478 <override>FileInfo</override>
479 <compatibility>NetWare only</compatibility>
482 <p>This directive is used to control how Apache finds the
483 interpreter used to run CGI scripts. For example, setting
484 <code>CGIMapExtension sys:\foo.nlm .foo</code> will
485 cause all CGI script files with a <code>.foo</code> extension to
486 be passed to the FOO interpreter.</p>
491 <name>ContentDigest</name>
492 <description>Enables the generation of <code>Content-MD5</code> HTTP Response
493 headers</description>
494 <syntax>ContentDigest On|Off</syntax>
495 <default>ContentDigest Off</default>
496 <contextlist><context>server config</context><context>virtual host</context>
497 <context>directory</context><context>.htaccess</context>
499 <override>Options</override>
500 <status>Experimental</status>
503 <p>This directive enables the generation of
504 <code>Content-MD5</code> headers as defined in RFC1864
505 respectively RFC2068.</p>
507 <p>MD5 is an algorithm for computing a "message digest"
508 (sometimes called "fingerprint") of arbitrary-length data, with
509 a high degree of confidence that any alterations in the data
510 will be reflected in alterations in the message digest.</p>
512 <p>The <code>Content-MD5</code> header provides an end-to-end
513 message integrity check (MIC) of the entity-body. A proxy or
514 client may check this header for detecting accidental
515 modification of the entity-body in transit. Example header:</p>
518 Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
521 <p>Note that this can cause performance problems on your server
522 since the message digest is computed on every request (the
523 values are not cached).</p>
525 <p><code>Content-MD5</code> is only sent for documents served
526 by the <module>core</module>, and not by any module. For example,
527 SSI documents, output from CGI scripts, and byte range responses
528 do not have this header.</p>
533 <name>DefaultType</name>
534 <description>MIME content-type that will be sent if the
535 server cannot determine a type in any other way</description>
536 <syntax>DefaultType <var>MIME-type|none</var></syntax>
537 <default>DefaultType text/plain</default>
538 <contextlist><context>server config</context><context>virtual host</context>
539 <context>directory</context><context>.htaccess</context>
541 <override>FileInfo</override>
544 <p>There will be times when the server is asked to provide a
545 document whose type cannot be determined by its <glossary
546 ref="mime-type">MIME types</glossary> mappings.</p>
548 <p>The server SHOULD inform the client of the content-type of the
549 document. If the server is unable to determine this by normal
550 means, it will set it to the configured
551 <code>DefaultType</code>. For example:</p>
554 DefaultType image/gif
557 <p>would be appropriate for a directory which contained many GIF
558 images with filenames missing the <code>.gif</code> extension.</p>
560 <p>In cases where it can neither be determined by the server nor
561 the administrator (e.g. a proxy), it is preferable to omit the MIME
562 type altogether rather than provide information that may be false.
563 This can be accomplished using</p>
567 <p>DefaultType None is only available in httpd-2.2.7 and later.</p>
569 <p>Note that unlike <directive
570 module="core">ForceType</directive>, this directive only
571 provides the default mime-type. All other mime-type definitions,
572 including filename extensions, that might identify the media type
573 will override this default.</p>
579 <description>Define the existence of a variable</description>
580 <syntax>Define <var>parameter-name</var></syntax>
581 <contextlist><context>server config</context></contextlist>
584 <p>Equivalent to passing the <code>-D</code> argument to <a
585 href="../programs/httpd.html">httpd</a>.</p>
586 <p>This directive can be used to toggle the use of <directive module="core"
587 type="section">IfDefine</directive> sections without needing to alter
588 <code>-D</code> arguments in any startup scripts.</p>
592 <directivesynopsis type="section">
593 <name>Directory</name>
594 <description>Enclose a group of directives that apply only to the
595 named file-system directory and sub-directories</description>
596 <syntax><Directory <var>directory-path</var>>
597 ... </Directory></syntax>
598 <contextlist><context>server config</context><context>virtual host</context>
602 <p><directive type="section">Directory</directive> and
603 <code></Directory></code> are used to enclose a group of
604 directives that will apply only to the named directory and
605 sub-directories of that directory. Any directive that is allowed
606 in a directory context may be used. <var>Directory-path</var> is
607 either the full path to a directory, or a wild-card string using
608 Unix shell-style matching. In a wild-card string, <code>?</code> matches
609 any single character, and <code>*</code> matches any sequences of
610 characters. You may also use <code>[]</code> character ranges. None
611 of the wildcards match a `/' character, so <code><Directory
612 /*/public_html></code> will not match
613 <code>/home/user/public_html</code>, but <code><Directory
614 /home/*/public_html></code> will match. Example:</p>
617 <Directory /usr/local/httpd/htdocs><br />
619 Options Indexes FollowSymLinks<br />
625 <p>Be careful with the <var>directory-path</var> arguments:
626 They have to literally match the filesystem path which Apache uses
627 to access the files. Directives applied to a particular
628 <code><Directory></code> will not apply to files accessed from
629 that same directory via a different path, such as via different symbolic
633 <p><glossary ref="regex">Regular
634 expressions</glossary> can also be used, with the addition of the
635 <code>~</code> character. For example:</p>
638 <Directory ~ "^/www/.*/[0-9]{3}">
641 <p>would match directories in <code>/www/</code> that consisted of
644 <p>If multiple (non-regular expression) <directive
645 type="section">Directory</directive> 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
649 href="#accessfilename">.htaccess</a> files. For example,
653 <Directory /><br />
655 AllowOverride None<br />
657 </Directory><br />
659 <Directory /home/><br />
661 AllowOverride FileInfo<br />
666 <p>for access to the document <code>/home/web/dir/doc.html</code>
670 <li>Apply directive <code>AllowOverride None</code>
671 (disabling <code>.htaccess</code> files).</li>
673 <li>Apply directive <code>AllowOverride FileInfo</code> (for
674 directory <code>/home</code>).</li>
676 <li>Apply any <code>FileInfo</code> directives in
677 <code>/home/.htaccess</code>, <code>/home/web/.htaccess</code> and
678 <code>/home/web/dir/.htaccess</code> in that order.</li>
681 <p>Regular expressions are not considered until after all of the
682 normal sections have been applied. Then all of the regular
683 expressions are tested in the order they appeared in the
684 configuration file. For example, with</p>
687 <Directory ~ abc$><br />
689 # ... directives here ...<br />
694 <p>the regular expression section won't be considered until after
695 all normal <directive type="section">Directory</directive>s and
696 <code>.htaccess</code> files have been applied. Then the regular
697 expression will match on <code>/home/abc/public_html/abc</code> and
698 the corresponding <directive type="section">Directory</directive> will
701 <p><strong>Note that the default Apache access for
702 <code><Directory /></code> is <code>Allow from All</code>.
703 This means that Apache will serve any file mapped from an URL. It is
704 recommended that you change this with a block such
708 <Directory /><br />
710 Order Deny,Allow<br />
716 <p><strong>and then override this for directories you
717 <em>want</em> accessible. See the <a
718 href="../misc/security_tips.html">Security Tips</a> page for more
719 details.</strong></p>
721 <p>The directory sections occur in the <code>httpd.conf</code> file.
722 <directive type="section">Directory</directive> directives
723 cannot nest, and cannot appear in a <directive module="core"
724 type="section">Limit</directive> or <directive module="core"
725 type="section">LimitExcept</directive> section.</p>
727 <seealso><a href="../sections.html">How <Directory>,
728 <Location> and <Files> sections work</a> for an
729 explanation of how these different sections are combined when a
730 request is received</seealso>
733 <directivesynopsis type="section">
734 <name>DirectoryMatch</name>
735 <description>Enclose directives that apply to
736 file-system directories matching a regular expression and their
737 subdirectories</description>
738 <syntax><DirectoryMatch <var>regex</var>>
739 ... </DirectoryMatch></syntax>
740 <contextlist><context>server config</context><context>virtual host</context>
744 <p><directive type="section">DirectoryMatch</directive> and
745 <code></DirectoryMatch></code> are used to enclose a group
746 of directives which will apply only to the named directory and
747 sub-directories of that directory, the same as <directive
748 module="core" type="section">Directory</directive>. However, it
749 takes as an argument a <glossary ref="regex">regular
750 expression</glossary>. For example:</p>
753 <DirectoryMatch "^/www/(.+/)?[0-9]{3}">
756 <p>would match directories in <code>/www/</code> that consisted of three
759 <seealso><directive type="section" module="core">Directory</directive> for
760 a description of how regular expressions are mixed in with normal
761 <directive type="section">Directory</directive>s</seealso>
763 href="../sections.html">How <Directory>, <Location> and
764 <Files> sections work</a> for an explanation of how these different
765 sections are combined when a request is received</seealso>
769 <name>DocumentRoot</name>
770 <description>Directory that forms the main document tree visible
771 from the web</description>
772 <syntax>DocumentRoot <var>directory-path</var></syntax>
773 <default>DocumentRoot /usr/local/apache/htdocs</default>
774 <contextlist><context>server config</context><context>virtual host</context>
778 <p>This directive sets the directory from which <program>httpd</program>
779 will serve files. Unless matched by a directive like <directive
780 module="mod_alias">Alias</directive>, the server appends the
781 path from the requested URL to the document root to make the
782 path to the document. Example:</p>
785 DocumentRoot /usr/web
789 <code>http://www.my.host.com/index.html</code> refers to
790 <code>/usr/web/index.html</code>. If the <var>directory-path</var> is
791 not absolute then it is assumed to be relative to the <directive
792 module="core">ServerRoot</directive>.</p>
794 <p>The <directive>DocumentRoot</directive> should be specified without
795 a trailing slash.</p>
797 <seealso><a href="../urlmapping.html#documentroot">Mapping URLs to Filesystem
798 Locations</a></seealso>
802 <name>EnableMMAP</name>
803 <description>Use memory-mapping to read files during delivery</description>
804 <syntax>EnableMMAP On|Off</syntax>
805 <default>EnableMMAP On</default>
806 <contextlist><context>server config</context><context>virtual host</context>
807 <context>directory</context><context>.htaccess</context>
809 <override>FileInfo</override>
812 <p>This directive controls whether the <program>httpd</program> 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 <module>mod_include</module> -- Apache
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 <program>httpd</program>.</li>
826 <li>With an NFS-mounted <directive module="core">DocumentRoot</directive>,
827 the <program>httpd</program> may crash due to a segmentation fault if a file
828 is deleted or truncated while the <program>httpd</program> has it
832 <p>For server configurations that are vulnerable to these problems,
833 you should disable memory-mapping of delivered files by specifying:</p>
839 <p>For NFS mounted files, this feature may be disabled explicitly for
840 the offending files by specifying:</p>
843 <Directory "/path-to-nfs-files">
853 <name>EnableSendfile</name>
854 <description>Use the kernel sendfile support to deliver files to the client</description>
855 <syntax>EnableSendfile On|Off</syntax>
856 <default>EnableSendfile On</default>
857 <contextlist><context>server config</context><context>virtual host</context>
858 <context>directory</context><context>.htaccess</context>
860 <override>FileInfo</override>
861 <compatibility>Available in version 2.0.44 and later</compatibility>
864 <p>This directive controls whether <program>httpd</program> may use the
865 sendfile support from the kernel to transmit file contents to the client.
866 By default, when the handling of a request requires no access
867 to the data within a file -- for example, when delivering a
868 static file -- Apache uses sendfile to deliver the file contents
869 without ever reading the file if the OS supports it.</p>
871 <p>This sendfile mechanism avoids separate read and send operations,
872 and buffer allocations. But on some platforms or within some
873 filesystems, it is better to disable this feature to avoid
874 operational problems:</p>
877 <li>Some platforms may have broken sendfile support that the build
878 system did not detect, especially if the binaries were built on
879 another box and moved to such a machine with broken sendfile
881 <li>On Linux the use of sendfile triggers TCP-checksum
882 offloading bugs on certain networking cards when using IPv6.</li>
883 <li>On Linux on Itanium, sendfile may be unable to handle files
884 over 2GB in size.</li>
885 <li>With a network-mounted <directive
886 module="core">DocumentRoot</directive> (e.g., NFS or SMB),
887 the kernel may be unable to serve the network file through
891 <p>For server configurations that are vulnerable to these problems,
892 you should disable this feature by specifying:</p>
898 <p>For NFS or SMB mounted files, this feature may be disabled explicitly
899 for the offending files by specifying:</p>
902 <Directory "/path-to-nfs-files">
912 <name>ErrorDocument</name>
913 <description>What the server will return to the client
914 in case of an error</description>
915 <syntax>ErrorDocument <var>error-code</var> <var>document</var></syntax>
916 <contextlist><context>server config</context><context>virtual host</context>
917 <context>directory</context><context>.htaccess</context>
919 <override>FileInfo</override>
920 <compatibility>Quoting syntax for text messages is different in Apache
924 <p>In the event of a problem or error, Apache can be configured
925 to do one of four things,</p>
928 <li>output a simple hardcoded error message</li>
930 <li>output a customized message</li>
932 <li>redirect to a local <var>URL-path</var> to handle the
935 <li>redirect to an external <var>URL</var> to handle the
939 <p>The first option is the default, while options 2-4 are
940 configured using the <directive>ErrorDocument</directive>
941 directive, which is followed by the HTTP response code and a URL
942 or a message. Apache will sometimes offer additional information
943 regarding the problem/error.</p>
945 <p>URLs can begin with a slash (/) for local web-paths (relative
946 to the <directive module="core">DocumentRoot</directive>), or be a
947 full URL which the client can resolve. Alternatively, a message
948 can be provided to be displayed by the browser. Examples:</p>
951 ErrorDocument 500 http://foo.example.com/cgi-bin/tester<br />
952 ErrorDocument 404 /cgi-bin/bad_urls.pl<br />
953 ErrorDocument 401 /subscription_info.html<br />
954 ErrorDocument 403 "Sorry can't allow you access today"
957 <p>Additionally, the special value <code>default</code> can be used
958 to specify Apache's simple hardcoded message. While not required
959 under normal circumstances, <code>default</code> will restore
960 Apache's simple hardcoded message for configurations that would
961 otherwise inherit an existing <directive>ErrorDocument</directive>.</p>
964 ErrorDocument 404 /cgi-bin/bad_urls.pl<br /><br />
965 <Directory /web/docs><br />
967 ErrorDocument 404 default<br />
972 <p>Note that when you specify an <directive>ErrorDocument</directive>
973 that points to a remote URL (ie. anything with a method such as
974 <code>http</code> in front of it), Apache will send a redirect to the
975 client to tell it where to find the document, even if the
976 document ends up being on the same server. This has several
977 implications, the most important being that the client will not
978 receive the original error status code, but instead will
979 receive a redirect status code. This in turn can confuse web
980 robots and other clients which try to determine if a URL is
981 valid using the status code. In addition, if you use a remote
982 URL in an <code>ErrorDocument 401</code>, the client will not
983 know to prompt the user for a password since it will not
984 receive the 401 status code. Therefore, <strong>if you use an
985 <code>ErrorDocument 401</code> directive then it must refer to a local
986 document.</strong></p>
988 <p>Microsoft Internet Explorer (MSIE) will by default ignore
989 server-generated error messages when they are "too small" and substitute
990 its own "friendly" error messages. The size threshold varies depending on
991 the type of error, but in general, if you make your error document
992 greater than 512 bytes, then MSIE will show the server-generated
993 error rather than masking it. More information is available in
994 Microsoft Knowledge Base article <a
995 href="http://support.microsoft.com/default.aspx?scid=kb;en-us;Q294807"
998 <p>Although most error messages can be overriden, there are certain
999 circumstances where the internal messages are used regardless of the
1000 setting of <directive module="core">ErrorDocument</directive>. In
1001 particular, if a malformed request is detected, normal request processing
1002 will be immediately halted and the internal error message returned.
1003 This is necessary to guard against security problems caused by
1006 <p>Prior to version 2.0, messages were indicated by prefixing
1007 them with a single unmatched double quote character.</p>
1010 <seealso><a href="../custom-error.html">documentation of
1011 customizable responses</a></seealso>
1012 </directivesynopsis>
1015 <name>ErrorLog</name>
1016 <description>Location where the server will log errors</description>
1017 <syntax> ErrorLog <var>file-path</var>|syslog[:<var>facility</var>]</syntax>
1018 <default>ErrorLog logs/error_log (Unix) ErrorLog logs/error.log (Windows and OS/2)</default>
1019 <contextlist><context>server config</context><context>virtual host</context>
1023 <p>The <directive>ErrorLog</directive> directive sets the name of
1024 the file to which the server will log any errors it encounters. If
1025 the <var>file-path</var> is not absolute then it is assumed to be
1026 relative to the <directive module="core">ServerRoot</directive>.</p>
1028 <example><title>Example</title>
1029 ErrorLog /var/log/httpd/error_log
1032 <p>If the <var>file-path</var>
1033 begins with a pipe (|) then it is assumed to be a command to spawn
1034 to handle the error log.</p>
1036 <example><title>Example</title>
1037 ErrorLog "|/usr/local/bin/httpd_errors"
1040 <p>Using <code>syslog</code> instead of a filename enables logging
1041 via syslogd(8) if the system supports it. The default is to use
1042 syslog facility <code>local7</code>, but you can override this by
1043 using the <code>syslog:<var>facility</var></code> syntax where
1044 <var>facility</var> can be one of the names usually documented in
1047 <example><title>Example</title>
1048 ErrorLog syslog:user
1051 <p>SECURITY: See the <a
1052 href="../misc/security_tips.html#serverroot">security tips</a>
1053 document for details on why your security could be compromised
1054 if the directory where log files are stored is writable by
1055 anyone other than the user that starts the server.</p>
1056 <note type="warning"><title>Note</title>
1057 <p>When entering a file path on non-Unix platforms, care should be taken
1058 to make sure that only forward slashed are used even though the platform
1059 may allow the use of back slashes. In general it is a good idea to always
1060 use forward slashes throughout the configuration files.</p>
1063 <seealso><directive module="core">LogLevel</directive></seealso>
1064 <seealso><a href="../logs.html">Apache Log Files</a></seealso>
1065 </directivesynopsis>
1068 <name>FileETag</name>
1069 <description>File attributes used to create the ETag
1070 HTTP response header</description>
1071 <syntax>FileETag <var>component</var> ...</syntax>
1072 <default>FileETag INode MTime Size</default>
1073 <contextlist><context>server config</context><context>virtual host</context>
1074 <context>directory</context><context>.htaccess</context>
1076 <override>FileInfo</override>
1080 The <directive>FileETag</directive> directive configures the file
1081 attributes that are used to create the <code>ETag</code> (entity
1082 tag) response header field when the document is based on a file.
1083 (The <code>ETag</code> value is used in cache management to save
1084 network bandwidth.) In Apache 1.3.22 and earlier, the
1085 <code>ETag</code> value was <em>always</em> formed
1086 from the file's inode, size, and last-modified time (mtime). The
1087 <directive>FileETag</directive> directive allows you to choose
1088 which of these -- if any -- should be used. The recognized keywords are:
1092 <dt><strong>INode</strong></dt>
1093 <dd>The file's i-node number will be included in the calculation</dd>
1094 <dt><strong>MTime</strong></dt>
1095 <dd>The date and time the file was last modified will be included</dd>
1096 <dt><strong>Size</strong></dt>
1097 <dd>The number of bytes in the file will be included</dd>
1098 <dt><strong>All</strong></dt>
1099 <dd>All available fields will be used. This is equivalent to:
1100 <example>FileETag INode MTime Size</example></dd>
1101 <dt><strong>None</strong></dt>
1102 <dd>If a document is file-based, no <code>ETag</code> field will be
1103 included in the response</dd>
1106 <p>The <code>INode</code>, <code>MTime</code>, and <code>Size</code>
1107 keywords may be prefixed with either <code>+</code> or <code>-</code>,
1108 which allow changes to be made to the default setting inherited
1109 from a broader scope. Any keyword appearing without such a prefix
1110 immediately and completely cancels the inherited setting.</p>
1112 <p>If a directory's configuration includes
1113 <code>FileETag INode MTime Size</code>, and a
1114 subdirectory's includes <code>FileETag -INode</code>,
1115 the setting for that subdirectory (which will be inherited by
1116 any sub-subdirectories that don't override it) will be equivalent to
1117 <code>FileETag MTime Size</code>.</p>
1118 <note type="warning"><title>Warning</title>
1119 Do not change the default for directories or locations that have WebDAV
1120 enabled and use <module>mod_dav_fs</module> as a storage provider.
1121 <module>mod_dav_fs</module> uses <code>INode MTime Size</code>
1122 as a fixed format for <code>ETag</code> comparisons on conditional requests.
1123 These conditional requests will break if the <code>ETag</code> format is
1124 changed via <directive>FileETag</directive>.
1127 </directivesynopsis>
1129 <directivesynopsis type="section">
1131 <description>Contains directives that apply to matched
1132 filenames</description>
1133 <syntax><Files <var>filename</var>> ... </Files></syntax>
1134 <contextlist><context>server config</context><context>virtual host</context>
1135 <context>directory</context><context>.htaccess</context>
1137 <override>All</override>
1140 <p>The <directive type="section">Files</directive> directive
1141 limits the scope of the enclosed directives by filename. It is comparable
1142 to the <directive module="core" type="section">Directory</directive>
1143 and <directive module="core" type="section">Location</directive>
1144 directives. It should be matched with a <code></Files></code>
1145 directive. The directives given within this section will be applied to
1146 any object with a basename (last component of filename) matching the
1147 specified filename. <directive type="section">Files</directive>
1148 sections are processed in the order they appear in the
1149 configuration file, after the <directive module="core"
1150 type="section">Directory</directive> sections and
1151 <code>.htaccess</code> files are read, but before <directive
1152 type="section" module="core">Location</directive> sections. Note
1153 that <directive type="section">Files</directive> can be nested
1154 inside <directive type="section"
1155 module="core">Directory</directive> sections to restrict the
1156 portion of the filesystem they apply to.</p>
1158 <p>The <var>filename</var> argument should include a filename, or
1159 a wild-card string, where <code>?</code> matches any single character,
1160 and <code>*</code> matches any sequences of characters.
1161 <glossary ref="regex">Regular expressions</glossary>
1162 can also be used, with the addition of the
1163 <code>~</code> character. For example:</p>
1166 <Files ~ "\.(gif|jpe?g|png)$">
1169 <p>would match most common Internet graphics formats. <directive
1170 module="core" type="section">FilesMatch</directive> is preferred,
1173 <p>Note that unlike <directive type="section"
1174 module="core">Directory</directive> and <directive type="section"
1175 module="core">Location</directive> sections, <directive
1176 type="section">Files</directive> sections can be used inside
1177 <code>.htaccess</code> files. This allows users to control access to
1178 their own files, at a file-by-file level.</p>
1181 <seealso><a href="../sections.html">How <Directory>, <Location>
1182 and <Files> sections work</a> for an explanation of how these
1183 different sections are combined when a request is received</seealso>
1184 </directivesynopsis>
1186 <directivesynopsis type="section">
1187 <name>FilesMatch</name>
1188 <description>Contains directives that apply to regular-expression matched
1189 filenames</description>
1190 <syntax><FilesMatch <var>regex</var>> ... </FilesMatch></syntax>
1191 <contextlist><context>server config</context><context>virtual host</context>
1192 <context>directory</context><context>.htaccess</context>
1194 <override>All</override>
1197 <p>The <directive type="section">FilesMatch</directive> directive
1198 limits the scope of the enclosed directives by filename, just as the
1199 <directive module="core" type="section">Files</directive> directive
1200 does. However, it accepts a <glossary ref="regex">regular
1201 expression</glossary>. For example:</p>
1204 <FilesMatch "\.(gif|jpe?g|png)$">
1207 <p>would match most common Internet graphics formats.</p>
1210 <seealso><a href="../sections.html">How <Directory>, <Location>
1211 and <Files> sections work</a> for an explanation of how these
1212 different sections are combined when a request is received</seealso>
1213 </directivesynopsis>
1216 <name>ForceType</name>
1217 <description>Forces all matching files to be served with the specified
1218 MIME content-type</description>
1219 <syntax>ForceType <var>MIME-type</var>|None</syntax>
1220 <contextlist><context>directory</context><context>.htaccess</context>
1222 <override>FileInfo</override>
1223 <compatibility>Moved to the core in Apache 2.0</compatibility>
1226 <p>When placed into an <code>.htaccess</code> file or a
1227 <directive type="section" module="core">Directory</directive>, or
1228 <directive type="section" module="core">Location</directive> or
1229 <directive type="section" module="core">Files</directive>
1230 section, this directive forces all matching files to be served
1231 with the content type identification given by
1232 <var>MIME-type</var>. For example, if you had a directory full of
1233 GIF files, but did not want to label them all with <code>.gif</code>,
1234 you might want to use:</p>
1240 <p>Note that unlike <directive module="core">DefaultType</directive>,
1241 this directive overrides all mime-type associations, including
1242 filename extensions, that might identify the media type.</p>
1244 <p>You can override any <directive>ForceType</directive> setting
1245 by using the value of <code>None</code>:</p>
1248 # force all files to be image/gif:<br />
1249 <Location /images><br />
1251 ForceType image/gif<br />
1253 </Location><br />
1255 # but normal mime-type associations here:<br />
1256 <Location /images/mixed><br />
1258 ForceType None<br />
1263 </directivesynopsis>
1266 <name>HostnameLookups</name>
1267 <description>Enables DNS lookups on client IP addresses</description>
1268 <syntax>HostnameLookups On|Off|Double</syntax>
1269 <default>HostnameLookups Off</default>
1270 <contextlist><context>server config</context><context>virtual host</context>
1271 <context>directory</context></contextlist>
1274 <p>This directive enables DNS lookups so that host names can be
1275 logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
1276 The value <code>Double</code> refers to doing double-reverse
1277 DNS lookup. That is, after a reverse lookup is performed, a forward
1278 lookup is then performed on that result. At least one of the IP
1279 addresses in the forward lookup must match the original
1280 address. (In "tcpwrappers" terminology this is called
1281 <code>PARANOID</code>.)</p>
1283 <p>Regardless of the setting, when <module>mod_authz_host</module> is
1284 used for controlling access by hostname, a double reverse lookup
1285 will be performed. This is necessary for security. Note that the
1286 result of this double-reverse isn't generally available unless you
1287 set <code>HostnameLookups Double</code>. For example, if only
1288 <code>HostnameLookups On</code> and a request is made to an object
1289 that is protected by hostname restrictions, regardless of whether
1290 the double-reverse fails or not, CGIs will still be passed the
1291 single-reverse result in <code>REMOTE_HOST</code>.</p>
1293 <p>The default is <code>Off</code> in order to save the network
1294 traffic for those sites that don't truly need the reverse
1295 lookups done. It is also better for the end users because they
1296 don't have to suffer the extra latency that a lookup entails.
1297 Heavily loaded sites should leave this directive
1298 <code>Off</code>, since DNS lookups can take considerable
1299 amounts of time. The utility <program>logresolve</program>, compiled by
1300 default to the <code>bin</code> subdirectory of your installation
1301 directory, can be used to look up host names from logged IP addresses
1304 </directivesynopsis>
1306 <directivesynopsis type="section">
1308 <description>Contains directives that apply only if a condition is
1309 satisfied by a request at runtime</description>
1310 <syntax><If <var>expression</var>> ... </If></syntax>
1311 <contextlist><context>server config</context><context>virtual host</context>
1312 <context>directory</context><context>.htaccess</context>
1314 <override>All</override>
1317 <p>The <directive type="section">If</directive> directive
1318 evaluates an expression at runtime, and applies the enclosed
1319 directives if and only if the expression evaluates to true.
1323 <If "$req{Host} = ''">
1326 <p>would match HTTP/1.0 requests without a <var>Host:</var> header.</p>
1329 <seealso><a href="../sections.html">How <Directory>, <Location>,
1330 <Files> sections work</a> for an explanation of how these
1331 different sections are combined when a request is received.
1332 <directive type="section">If</directive> has the same precedence
1333 and usage as <directive type="section">Files</directive></seealso>
1334 </directivesynopsis>
1336 <directivesynopsis type="section">
1337 <name>IfDefine</name>
1338 <description>Encloses directives that will be processed only
1339 if a test is true at startup</description>
1340 <syntax><IfDefine [!]<var>parameter-name</var>> ...
1341 </IfDefine></syntax>
1342 <contextlist><context>server config</context><context>virtual host</context>
1343 <context>directory</context><context>.htaccess</context>
1345 <override>All</override>
1348 <p>The <code><IfDefine <var>test</var>>...</IfDefine>
1349 </code> section is used to mark directives that are conditional. The
1350 directives within an <directive type="section">IfDefine</directive>
1351 section are only processed if the <var>test</var> is true. If <var>
1352 test</var> is false, everything between the start and end markers is
1355 <p>The <var>test</var> in the <directive type="section"
1356 >IfDefine</directive> section directive can be one of two forms:</p>
1359 <li><var>parameter-name</var></li>
1361 <li><code>!</code><var>parameter-name</var></li>
1364 <p>In the former case, the directives between the start and end
1365 markers are only processed if the parameter named
1366 <var>parameter-name</var> is defined. The second format reverses
1367 the test, and only processes the directives if
1368 <var>parameter-name</var> is <strong>not</strong> defined.</p>
1370 <p>The <var>parameter-name</var> argument is a define as given on the
1371 <program>httpd</program> command line via <code>-D<var>parameter</var>
1372 </code> at the time the server was started or by the <directive
1373 module="core">Define</directive> directive.</p>
1375 <p><directive type="section">IfDefine</directive> sections are
1376 nest-able, which can be used to implement simple
1377 multiple-parameter tests. Example:</p>
1380 httpd -DReverseProxy ...<br />
1383 <IfDefine ReverseProxy><br />
1385 LoadModule rewrite_module modules/mod_rewrite.so<br />
1386 LoadModule proxy_module modules/libproxy.so<br />
1391 </directivesynopsis>
1393 <directivesynopsis type="section">
1394 <name>IfModule</name>
1395 <description>Encloses directives that are processed conditional on the
1396 presence or absence of a specific module</description>
1397 <syntax><IfModule [!]<var>module-file</var>|<var>module-identifier</var>> ...
1398 </IfModule></syntax>
1399 <contextlist><context>server config</context><context>virtual host</context>
1400 <context>directory</context><context>.htaccess</context>
1402 <override>All</override>
1403 <compatibility>Module identifiers are available in version 2.1 and
1404 later.</compatibility>
1407 <p>The <code><IfModule <var>test</var>>...</IfModule></code>
1408 section is used to mark directives that are conditional on the presence of
1409 a specific module. The directives within an <directive type="section"
1410 >IfModule</directive> section are only processed if the <var>test</var>
1411 is true. If <var>test</var> is false, everything between the start and
1412 end markers is ignored.</p>
1414 <p>The <var>test</var> in the <directive type="section"
1415 >IfModule</directive> section directive can be one of two forms:</p>
1418 <li><var>module</var></li>
1420 <li>!<var>module</var></li>
1423 <p>In the former case, the directives between the start and end
1424 markers are only processed if the module named <var>module</var>
1425 is included in Apache -- either compiled in or
1426 dynamically loaded using <directive module="mod_so"
1427 >LoadModule</directive>. The second format reverses the test,
1428 and only processes the directives if <var>module</var> is
1429 <strong>not</strong> included.</p>
1431 <p>The <var>module</var> argument can be either the module identifier or
1432 the file name of the module, at the time it was compiled. For example,
1433 <code>rewrite_module</code> is the identifier and
1434 <code>mod_rewrite.c</code> is the file name. If a module consists of
1435 several source files, use the name of the file containing the string
1436 <code>STANDARD20_MODULE_STUFF</code>.</p>
1438 <p><directive type="section">IfModule</directive> sections are
1439 nest-able, which can be used to implement simple multiple-module
1442 <note>This section should only be used if you need to have one
1443 configuration file that works whether or not a specific module
1444 is available. In normal operation, directives need not be
1445 placed in <directive type="section">IfModule</directive>
1448 </directivesynopsis>
1451 <name>Include</name>
1452 <description>Includes other configuration files from within
1453 the server configuration files</description>
1454 <syntax>Include <var>file-path</var>|<var>directory-path</var></syntax>
1455 <contextlist><context>server config</context><context>virtual host</context>
1456 <context>directory</context>
1458 <compatibility>Wildcard matching available in 2.0.41 and later</compatibility>
1461 <p>This directive allows inclusion of other configuration files
1462 from within the server configuration files.</p>
1464 <p>Shell-style (<code>fnmatch()</code>) wildcard characters can be used to
1465 include several files at once, in alphabetical order. In
1466 addition, if <directive>Include</directive> points to a directory,
1467 rather than a file, Apache will read all files in that directory
1468 and any subdirectory. But including entire directories is not
1469 recommended, because it is easy to accidentally leave temporary
1470 files in a directory that can cause <program>httpd</program> to
1473 <p>The file path specified may be an absolute path, or may be relative
1474 to the <directive module="core">ServerRoot</directive> directory.</p>
1479 Include /usr/local/apache2/conf/ssl.conf<br />
1480 Include /usr/local/apache2/conf/vhosts/*.conf
1483 <p>Or, providing paths relative to your <directive
1484 module="core">ServerRoot</directive> directory:</p>
1487 Include conf/ssl.conf<br />
1488 Include conf/vhosts/*.conf
1491 <p>Running <code>apachectl configtest</code> will give you a list
1492 of the files that are being processed during the configuration
1496 root@host# apachectl configtest<br />
1497 Processing config file: /usr/local/apache2/conf/ssl.conf<br />
1498 Processing config file: /usr/local/apache2/conf/vhosts/vhost1.conf<br />
1499 Processing config file: /usr/local/apache2/conf/vhosts/vhost2.conf<br />
1504 <seealso><program>apachectl</program></seealso>
1505 </directivesynopsis>
1508 <name>KeepAlive</name>
1509 <description>Enables HTTP persistent connections</description>
1510 <syntax>KeepAlive On|Off</syntax>
1511 <default>KeepAlive On</default>
1512 <contextlist><context>server config</context><context>virtual host</context>
1516 <p>The Keep-Alive extension to HTTP/1.0 and the persistent
1517 connection feature of HTTP/1.1 provide long-lived HTTP sessions
1518 which allow multiple requests to be sent over the same TCP
1519 connection. In some cases this has been shown to result in an
1520 almost 50% speedup in latency times for HTML documents with
1521 many images. To enable Keep-Alive connections, set
1522 <code>KeepAlive On</code>.</p>
1524 <p>For HTTP/1.0 clients, Keep-Alive connections will only be
1525 used if they are specifically requested by a client. In
1526 addition, a Keep-Alive connection with an HTTP/1.0 client can
1527 only be used when the length of the content is known in
1528 advance. This implies that dynamic content such as CGI output,
1529 SSI pages, and server-generated directory listings will
1530 generally not use Keep-Alive connections to HTTP/1.0 clients.
1531 For HTTP/1.1 clients, persistent connections are the default
1532 unless otherwise specified. If the client requests it, chunked
1533 encoding will be used in order to send content of unknown
1534 length over persistent connections.</p>
1536 <p>When a client uses a Keep-Alive connection it will be counted
1537 as a single "request" for the MaxRequestsPerChild directive, regardless
1538 of how many requests are sent using the connection.</p>
1541 <seealso><directive module="core">MaxKeepAliveRequests</directive></seealso>
1542 </directivesynopsis>
1545 <name>KeepAliveTimeout</name>
1546 <description>Amount of time the server will wait for subsequent
1547 requests on a persistent connection</description>
1548 <syntax>KeepAliveTimeout <var>seconds</var></syntax>
1549 <default>KeepAliveTimeout 5</default>
1550 <contextlist><context>server config</context><context>virtual host</context>
1554 <p>The number of seconds Apache will wait for a subsequent
1555 request before closing the connection. Once a request has been
1556 received, the timeout value specified by the
1557 <directive module="core">Timeout</directive> directive applies.</p>
1559 <p>Setting <directive>KeepAliveTimeout</directive> to a high value
1560 may cause performance problems in heavily loaded servers. The
1561 higher the timeout, the more server processes will be kept
1562 occupied waiting on connections with idle clients.</p>
1564 </directivesynopsis>
1566 <directivesynopsis type="section">
1568 <description>Restrict enclosed access controls to only certain HTTP
1569 methods</description>
1570 <syntax><Limit <var>method</var> [<var>method</var>] ... > ...
1571 </Limit></syntax>
1572 <contextlist><context>server config</context><context>virtual host</context>
1573 <context>directory</context><context>.htaccess</context>
1575 <override>All</override>
1578 <p>Access controls are normally effective for
1579 <strong>all</strong> access methods, and this is the usual
1580 desired behavior. <strong>In the general case, access control
1581 directives should not be placed within a
1582 <directive type="section">Limit</directive> section.</strong></p>
1584 <p>The purpose of the <directive type="section">Limit</directive>
1585 directive is to restrict the effect of the access controls to the
1586 nominated HTTP methods. For all other methods, the access
1587 restrictions that are enclosed in the <directive
1588 type="section">Limit</directive> bracket <strong>will have no
1589 effect</strong>. The following example applies the access control
1590 only to the methods <code>POST</code>, <code>PUT</code>, and
1591 <code>DELETE</code>, leaving all other methods unprotected:</p>
1594 <Limit POST PUT DELETE><br />
1596 Require valid-user<br />
1601 <p>The method names listed can be one or more of: <code>GET</code>,
1602 <code>POST</code>, <code>PUT</code>, <code>DELETE</code>,
1603 <code>CONNECT</code>, <code>OPTIONS</code>,
1604 <code>PATCH</code>, <code>PROPFIND</code>, <code>PROPPATCH</code>,
1605 <code>MKCOL</code>, <code>COPY</code>, <code>MOVE</code>,
1606 <code>LOCK</code>, and <code>UNLOCK</code>. <strong>The method name is
1607 case-sensitive.</strong> If <code>GET</code> is used it will also
1608 restrict <code>HEAD</code> requests. The <code>TRACE</code> method
1609 cannot be limited (see <directive type="section" module="core"
1610 >TraceEnable</directive>).</p>
1612 <note type="warning">A <directive type="section"
1613 module="core">LimitExcept</directive> section should always be
1614 used in preference to a <directive type="section"
1615 module="core">Limit</directive> section when restricting access,
1616 since a <directive type="section"
1617 module="core">LimitExcept</directive> section provides protection
1618 against arbitrary methods.</note>
1621 </directivesynopsis>
1623 <directivesynopsis type="section">
1624 <name>LimitExcept</name>
1625 <description>Restrict access controls to all HTTP methods
1626 except the named ones</description>
1627 <syntax><LimitExcept <var>method</var> [<var>method</var>] ... > ...
1628 </LimitExcept></syntax>
1629 <contextlist><context>server config</context><context>virtual host</context>
1630 <context>directory</context><context>.htaccess</context>
1632 <override>All</override>
1635 <p><directive type="section">LimitExcept</directive> and
1636 <code></LimitExcept></code> are used to enclose
1637 a group of access control directives which will then apply to any
1638 HTTP access method <strong>not</strong> listed in the arguments;
1639 i.e., it is the opposite of a <directive type="section"
1640 module="core">Limit</directive> section and can be used to control
1641 both standard and nonstandard/unrecognized methods. See the
1642 documentation for <directive module="core"
1643 type="section">Limit</directive> for more details.</p>
1648 <LimitExcept POST GET><br />
1650 Require valid-user<br />
1652 </LimitExcept>
1656 </directivesynopsis>
1659 <name>LimitInternalRecursion</name>
1660 <description>Determine maximum number of internal redirects and nested
1661 subrequests</description>
1662 <syntax>LimitInternalRecursion <var>number</var> [<var>number</var>]</syntax>
1663 <default>LimitInternalRecursion 10</default>
1664 <contextlist><context>server config</context><context>virtual host</context>
1666 <compatibility>Available in Apache 2.0.47 and later</compatibility>
1669 <p>An internal redirect happens, for example, when using the <directive
1670 module="mod_actions">Action</directive> directive, which internally
1671 redirects the original request to a CGI script. A subrequest is Apache's
1672 mechanism to find out what would happen for some URI if it were requested.
1673 For example, <module>mod_dir</module> uses subrequests to look for the
1674 files listed in the <directive module="mod_dir">DirectoryIndex</directive>
1677 <p><directive>LimitInternalRecursion</directive> prevents the server
1678 from crashing when entering an infinite loop of internal redirects or
1679 subrequests. Such loops are usually caused by misconfigurations.</p>
1681 <p>The directive stores two different limits, which are evaluated on
1682 per-request basis. The first <var>number</var> is the maximum number of
1683 internal redirects, that may follow each other. The second <var>number</var>
1684 determines, how deep subrequests may be nested. If you specify only one
1685 <var>number</var>, it will be assigned to both limits.</p>
1687 <example><title>Example</title>
1688 LimitInternalRecursion 5
1691 </directivesynopsis>
1694 <name>LimitRequestBody</name>
1695 <description>Restricts the total size of the HTTP request body sent
1696 from the client</description>
1697 <syntax>LimitRequestBody <var>bytes</var></syntax>
1698 <default>LimitRequestBody 0</default>
1699 <contextlist><context>server config</context><context>virtual host</context>
1700 <context>directory</context><context>.htaccess</context>
1702 <override>All</override>
1705 <p>This directive specifies the number of <var>bytes</var> from 0
1706 (meaning unlimited) to 2147483647 (2GB) that are allowed in a
1709 <p>The <directive>LimitRequestBody</directive> directive allows
1710 the user to set a limit on the allowed size of an HTTP request
1711 message body within the context in which the directive is given
1712 (server, per-directory, per-file or per-location). If the client
1713 request exceeds that limit, the server will return an error
1714 response instead of servicing the request. The size of a normal
1715 request message body will vary greatly depending on the nature of
1716 the resource and the methods allowed on that resource. CGI scripts
1717 typically use the message body for retrieving form information.
1718 Implementations of the <code>PUT</code> method will require
1719 a value at least as large as any representation that the server
1720 wishes to accept for that resource.</p>
1722 <p>This directive gives the server administrator greater
1723 control over abnormal client request behavior, which may be
1724 useful for avoiding some forms of denial-of-service
1727 <p>If, for example, you are permitting file upload to a particular
1728 location, and wish to limit the size of the uploaded file to 100K,
1729 you might use the following directive:</p>
1732 LimitRequestBody 102400
1736 </directivesynopsis>
1739 <name>LimitRequestFields</name>
1740 <description>Limits the number of HTTP request header fields that
1741 will be accepted from the client</description>
1742 <syntax>LimitRequestFields <var>number</var></syntax>
1743 <default>LimitRequestFields 100</default>
1744 <contextlist><context>server config</context></contextlist>
1747 <p><var>Number</var> is an integer from 0 (meaning unlimited) to
1748 32767. The default value is defined by the compile-time
1749 constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
1752 <p>The <directive>LimitRequestFields</directive> directive allows
1753 the server administrator to modify the limit on the number of
1754 request header fields allowed in an HTTP request. A server needs
1755 this value to be larger than the number of fields that a normal
1756 client request might include. The number of request header fields
1757 used by a client rarely exceeds 20, but this may vary among
1758 different client implementations, often depending upon the extent
1759 to which a user has configured their browser to support detailed
1760 content negotiation. Optional HTTP extensions are often expressed
1761 using request header fields.</p>
1763 <p>This directive gives the server administrator greater
1764 control over abnormal client request behavior, which may be
1765 useful for avoiding some forms of denial-of-service attacks.
1766 The value should be increased if normal clients see an error
1767 response from the server that indicates too many fields were
1768 sent in the request.</p>
1773 LimitRequestFields 50
1777 </directivesynopsis>
1780 <name>LimitRequestFieldSize</name>
1781 <description>Limits the size of the HTTP request header allowed from the
1782 client</description>
1783 <syntax>LimitRequestFieldSize <var>bytes</var></syntax>
1784 <default>LimitRequestFieldSize 8190</default>
1785 <contextlist><context>server config</context></contextlist>
1788 <p>This directive specifies the number of <var>bytes</var>
1789 that will be allowed in an HTTP request header.</p>
1791 <p>The <directive>LimitRequestFieldSize</directive> directive
1792 allows the server administrator to reduce or increase the limit
1793 on the allowed size of an HTTP request header field. A server
1794 needs this value to be large enough to hold any one header field
1795 from a normal client request. The size of a normal request header
1796 field will vary greatly among different client implementations,
1797 often depending upon the extent to which a user has configured
1798 their browser to support detailed content negotiation. SPNEGO
1799 authentication headers can be up to 12392 bytes.</p>
1801 <p>This directive gives the server administrator greater
1802 control over abnormal client request behavior, which may be
1803 useful for avoiding some forms of denial-of-service attacks.</p>
1808 LimitRequestFieldSize 4094
1811 <note>Under normal conditions, the value should not be changed from
1815 </directivesynopsis>
1818 <name>LimitRequestLine</name>
1819 <description>Limit the size of the HTTP request line that will be accepted
1820 from the client</description>
1821 <syntax>LimitRequestLine <var>bytes</var></syntax>
1822 <default>LimitRequestLine 8190</default>
1823 <contextlist><context>server config</context></contextlist>
1826 <p>This directive sets the number of <var>bytes</var> that will be
1827 allowed on the HTTP request-line.</p>
1829 <p>The <directive>LimitRequestLine</directive> directive allows
1830 the server administrator to reduce or increase the limit on the allowed size
1831 of a client's HTTP request-line. Since the request-line consists of the
1832 HTTP method, URI, and protocol version, the
1833 <directive>LimitRequestLine</directive> directive places a
1834 restriction on the length of a request-URI allowed for a request
1835 on the server. A server needs this value to be large enough to
1836 hold any of its resource names, including any information that
1837 might be passed in the query part of a <code>GET</code> request.</p>
1839 <p>This directive gives the server administrator greater
1840 control over abnormal client request behavior, which may be
1841 useful for avoiding some forms of denial-of-service attacks.</p>
1846 LimitRequestLine 4094
1849 <note>Under normal conditions, the value should not be changed from
1852 </directivesynopsis>
1855 <name>LimitXMLRequestBody</name>
1856 <description>Limits the size of an XML-based request body</description>
1857 <syntax>LimitXMLRequestBody <var>bytes</var></syntax>
1858 <default>LimitXMLRequestBody 1000000</default>
1859 <contextlist><context>server config</context><context>virtual host</context>
1860 <context>directory</context><context>.htaccess</context></contextlist>
1861 <override>All</override>
1864 <p>Limit (in bytes) on maximum size of an XML-based request
1865 body. A value of <code>0</code> will disable any checking.</p>
1870 LimitXMLRequestBody 0
1874 </directivesynopsis>
1876 <directivesynopsis type="section">
1877 <name>Location</name>
1878 <description>Applies the enclosed directives only to matching
1880 <syntax><Location
1881 <var>URL-path</var>|<var>URL</var>> ... </Location></syntax>
1882 <contextlist><context>server config</context><context>virtual host</context>
1886 <p>The <directive type="section">Location</directive> directive
1887 limits the scope of the enclosed directives by URL. It is similar to the
1888 <directive type="section" module="core">Directory</directive>
1889 directive, and starts a subsection which is terminated with a
1890 <code></Location></code> directive. <directive
1891 type="section">Location</directive> sections are processed in the
1892 order they appear in the configuration file, after the <directive
1893 type="section" module="core">Directory</directive> sections and
1894 <code>.htaccess</code> files are read, and after the <directive
1895 type="section" module="core">Files</directive> sections.</p>
1897 <p><directive type="section">Location</directive> sections operate
1898 completely outside the filesystem. This has several consequences.
1899 Most importantly, <directive type="section">Location</directive>
1900 directives should not be used to control access to filesystem
1901 locations. Since several different URLs may map to the same
1902 filesystem location, such access controls may by circumvented.</p>
1904 <note><title>When to use <directive
1905 type="section">Location</directive></title>
1907 <p>Use <directive type="section">Location</directive> to apply
1908 directives to content that lives outside the filesystem. For
1909 content that lives in the filesystem, use <directive
1910 type="section" module="core">Directory</directive> and <directive
1911 type="section" module="core">Files</directive>. An exception is
1912 <code><Location /></code>, which is an easy way to
1913 apply a configuration to the entire server.</p>
1916 <p>For all origin (non-proxy) requests, the URL to be matched is a
1917 URL-path of the form <code>/path/</code>. No scheme, hostname,
1918 port, or query string may be included. For proxy requests, the
1919 URL to be matched is of the form
1920 <code>scheme://servername/path</code>, and you must include the
1923 <p>The URL may use wildcards. In a wild-card string, <code>?</code> matches
1924 any single character, and <code>*</code> matches any sequences of
1925 characters. Neither wildcard character matches a / in the URL-path.</p>
1927 <p><glossary ref="regex">Regular expressions</glossary>
1928 can also be used, with the addition of the
1929 <code>~</code> character. For example:</p>
1932 <Location ~ "/(extra|special)/data">
1935 <p>would match URLs that contained the substring <code>/extra/data</code>
1936 or <code>/special/data</code>. The directive <directive
1937 type="section" module="core">LocationMatch</directive> behaves
1938 identical to the regex version of <directive
1939 type="section">Location</directive>.</p>
1941 <p>The <directive type="section">Location</directive>
1942 functionality is especially useful when combined with the
1943 <directive module="core">SetHandler</directive>
1944 directive. For example, to enable status requests, but allow them
1945 only from browsers at <code>foo.com</code>, you might use:</p>
1948 <Location /status><br />
1950 SetHandler server-status<br />
1951 Order Deny,Allow<br />
1953 Allow from .foo.com<br />
1958 <note><title>Note about / (slash)</title>
1959 <p>The slash character has special meaning depending on where in a
1960 URL it appears. People may be used to its behavior in the filesystem
1961 where multiple adjacent slashes are frequently collapsed to a single
1962 slash (<em>i.e.</em>, <code>/home///foo</code> is the same as
1963 <code>/home/foo</code>). In URL-space this is not necessarily true.
1964 The <directive type="section" module="core">LocationMatch</directive>
1965 directive and the regex version of <directive type="section"
1966 >Location</directive> require you to explicitly specify multiple
1967 slashes if that is your intention.</p>
1969 <p>For example, <code><LocationMatch ^/abc></code> would match
1970 the request URL <code>/abc</code> but not the request URL <code>
1971 //abc</code>. The (non-regex) <directive type="section"
1972 >Location</directive> directive behaves similarly when used for
1973 proxy requests. But when (non-regex) <directive type="section"
1974 >Location</directive> is used for non-proxy requests it will
1975 implicitly match multiple slashes with a single slash. For example,
1976 if you specify <code><Location /abc/def></code> and the
1977 request is to <code>/abc//def</code> then it will match.</p>
1980 <seealso><a href="../sections.html">How <Directory>, <Location>
1981 and <Files> sections work</a> for an explanation of how these
1982 different sections are combined when a request is received</seealso>
1983 </directivesynopsis>
1985 <directivesynopsis type="section">
1986 <name>LocationMatch</name>
1987 <description>Applies the enclosed directives only to regular-expression
1988 matching URLs</description>
1989 <syntax><LocationMatch
1990 <var>regex</var>> ... </LocationMatch></syntax>
1991 <contextlist><context>server config</context><context>virtual host</context>
1995 <p>The <directive type="section">LocationMatch</directive> directive
1996 limits the scope of the enclosed directives by URL, in an identical manner
1997 to <directive module="core" type="section">Location</directive>. However,
1998 it takes a <glossary ref="regex">regular expression</glossary>
1999 as an argument instead of a simple string. For example:</p>
2002 <LocationMatch "/(extra|special)/data">
2005 <p>would match URLs that contained the substring <code>/extra/data</code>
2006 or <code>/special/data</code>.</p>
2009 <seealso><a href="../sections.html">How <Directory>, <Location>
2010 and <Files> sections work</a> for an explanation of how these
2011 different sections are combined when a request is received</seealso>
2012 </directivesynopsis>
2015 <name>LogLevel</name>
2016 <description>Controls the verbosity of the ErrorLog</description>
2017 <syntax>LogLevel <var>level</var></syntax>
2018 <default>LogLevel warn</default>
2019 <contextlist><context>server config</context><context>virtual host</context>
2023 <p><directive>LogLevel</directive> adjusts the verbosity of the
2024 messages recorded in the error logs (see <directive
2025 module="core">ErrorLog</directive> directive). The following
2026 <var>level</var>s are available, in order of decreasing
2030 <columnspec><column width=".2"/><column width=".3"/><column width=".5"/>
2033 <th><strong>Level</strong> </th>
2035 <th><strong>Description</strong> </th>
2037 <th><strong>Example</strong> </th>
2041 <td><code>emerg</code> </td>
2043 <td>Emergencies - system is unusable.</td>
2045 <td>"Child cannot open lock file. Exiting"</td>
2049 <td><code>alert</code> </td>
2051 <td>Action must be taken immediately.</td>
2053 <td>"getpwuid: couldn't determine user name from uid"</td>
2057 <td><code>crit</code> </td>
2059 <td>Critical Conditions.</td>
2061 <td>"socket: Failed to get a socket, exiting child"</td>
2065 <td><code>error</code> </td>
2067 <td>Error conditions.</td>
2069 <td>"Premature end of script headers"</td>
2073 <td><code>warn</code> </td>
2075 <td>Warning conditions.</td>
2077 <td>"child process 1234 did not exit, sending another
2082 <td><code>notice</code> </td>
2084 <td>Normal but significant condition.</td>
2086 <td>"httpd: caught SIGBUS, attempting to dump core in
2091 <td><code>info</code> </td>
2093 <td>Informational.</td>
2095 <td>"Server seems busy, (you may need to increase
2096 StartServers, or Min/MaxSpareServers)..."</td>
2100 <td><code>debug</code> </td>
2102 <td>Debug-level messages</td>
2104 <td>"Opening config file ..."</td>
2108 <p>When a particular level is specified, messages from all
2109 other levels of higher significance will be reported as well.
2110 <em>E.g.</em>, when <code>LogLevel info</code> is specified,
2111 then messages with log levels of <code>notice</code> and
2112 <code>warn</code> will also be posted.</p>
2114 <p>Using a level of at least <code>crit</code> is
2123 <note><title>Note</title>
2124 <p>When logging to a regular file messages of the level
2125 <code>notice</code> cannot be suppressed and thus are always
2126 logged. However, this doesn't apply when logging is done
2127 using <code>syslog</code>.</p>
2130 </directivesynopsis>
2133 <name>MaxKeepAliveRequests</name>
2134 <description>Number of requests allowed on a persistent
2135 connection</description>
2136 <syntax>MaxKeepAliveRequests <var>number</var></syntax>
2137 <default>MaxKeepAliveRequests 100</default>
2138 <contextlist><context>server config</context><context>virtual host</context>
2142 <p>The <directive>MaxKeepAliveRequests</directive> directive
2143 limits the number of requests allowed per connection when
2144 <directive module="core" >KeepAlive</directive> is on. If it is
2145 set to <code>0</code>, unlimited requests will be allowed. We
2146 recommend that this setting be kept to a high value for maximum
2147 server performance.</p>
2152 MaxKeepAliveRequests 500
2155 </directivesynopsis>
2158 <name>NameVirtualHost</name>
2159 <description>Designates an IP address for name-virtual
2160 hosting</description>
2161 <syntax>NameVirtualHost <var>addr</var>[:<var>port</var>]</syntax>
2162 <contextlist><context>server config</context></contextlist>
2165 <p>The <directive>NameVirtualHost</directive> directive is a
2166 required directive if you want to configure <a
2167 href="../vhosts/">name-based virtual hosts</a>.</p>
2169 <p>Although <var>addr</var> can be hostname it is recommended
2170 that you always use an IP address, e.g.</p>
2173 NameVirtualHost 111.22.33.44
2176 <p>With the <directive>NameVirtualHost</directive> directive you
2177 specify the IP address on which the server will receive requests
2178 for the name-based virtual hosts. This will usually be the address
2179 to which your name-based virtual host names resolve. In cases
2180 where a firewall or other proxy receives the requests and forwards
2181 them on a different IP address to the server, you must specify the
2182 IP address of the physical interface on the machine which will be
2183 servicing the requests. If you have multiple name-based hosts on
2184 multiple addresses, repeat the directive for each address.</p>
2186 <note><title>Note</title>
2187 <p>Note, that the "main server" and any <code>_default_</code> servers
2188 will <strong>never</strong> be served for a request to a
2189 <directive>NameVirtualHost</directive> IP address (unless for some
2190 reason you specify <directive>NameVirtualHost</directive> but then
2191 don't define any <directive>VirtualHost</directive>s for that
2195 <p>Optionally you can specify a port number on which the
2196 name-based virtual hosts should be used, e.g.</p>
2199 NameVirtualHost 111.22.33.44:8080
2202 <p>IPv6 addresses must be enclosed in square brackets, as shown
2203 in the following example:</p>
2206 NameVirtualHost [2001:db8::a00:20ff:fea7:ccea]:8080
2209 <p>To receive requests on all interfaces, you can use an argument of
2216 <note><title>Argument to <directive type="section">VirtualHost</directive>
2218 <p>Note that the argument to the <directive
2219 type="section">VirtualHost</directive> directive must
2220 exactly match the argument to the <directive
2221 >NameVirtualHost</directive> directive.</p>
2224 NameVirtualHost 1.2.3.4<br />
2225 <VirtualHost 1.2.3.4><br />
2227 </VirtualHost><br />
2232 <seealso><a href="../vhosts/">Virtual Hosts
2233 documentation</a></seealso>
2235 </directivesynopsis>
2238 <name>Options</name>
2239 <description>Configures what features are available in a particular
2240 directory</description>
2242 [+|-]<var>option</var> [[+|-]<var>option</var>] ...</syntax>
2243 <default>Options All</default>
2244 <contextlist><context>server config</context><context>virtual host</context>
2245 <context>directory</context><context>.htaccess</context>
2247 <override>Options</override>
2250 <p>The <directive>Options</directive> directive controls which
2251 server features are available in a particular directory.</p>
2253 <p><var>option</var> can be set to <code>None</code>, in which
2254 case none of the extra features are enabled, or one or more of
2258 <dt><code>All</code></dt>
2260 <dd>All options except for <code>MultiViews</code>. This is the default
2263 <dt><code>ExecCGI</code></dt>
2266 Execution of CGI scripts using <module>mod_cgi</module>
2269 <dt><code>FollowSymLinks</code></dt>
2273 The server will follow symbolic links in this directory.
2275 <p>Even though the server follows the symlink it does <em>not</em>
2276 change the pathname used to match against <directive type="section"
2277 module="core">Directory</directive> sections.</p>
2278 <p>Note also, that this option <strong>gets ignored</strong> if set
2279 inside a <directive type="section" module="core">Location</directive>
2281 <p>Omitting this option should not be considered a security restriction,
2282 since symlink testing is subject to race conditions that make it
2286 <dt><code>Includes</code></dt>
2289 Server-side includes provided by <module>mod_include</module>
2292 <dt><code>IncludesNOEXEC</code></dt>
2296 Server-side includes are permitted, but the <code>#exec
2297 cmd</code> and <code>#exec cgi</code> are disabled. It is still
2298 possible to <code>#include virtual</code> CGI scripts from
2299 <directive module="mod_alias">ScriptAlias</directive>ed
2302 <dt><code>Indexes</code></dt>
2305 If a URL which maps to a directory is requested, and there
2306 is no <directive module="mod_dir">DirectoryIndex</directive>
2307 (<em>e.g.</em>, <code>index.html</code>) in that directory, then
2308 <module>mod_autoindex</module> will return a formatted listing
2309 of the directory.</dd>
2311 <dt><code>MultiViews</code></dt>
2314 <a href="../content-negotiation.html">Content negotiated</a>
2315 "MultiViews" are allowed using
2316 <module>mod_negotiation</module>.</dd>
2318 <dt><code>SymLinksIfOwnerMatch</code></dt>
2320 <dd>The server will only follow symbolic links for which the
2321 target file or directory is owned by the same user id as the
2324 <note><title>Note</title> <p>This option gets ignored if
2325 set inside a <directive module="core"
2326 type="section">Location</directive> section.</p>
2327 <p>This option should not be considered a security restriction,
2328 since symlink testing is subject to race conditions that make it
2329 circumventable.</p></note>
2333 <p>Normally, if multiple <directive>Options</directive> could
2334 apply to a directory, then the most specific one is used and
2335 others are ignored; the options are not merged. (See <a
2336 href="../sections.html#mergin">how sections are merged</a>.)
2337 However if <em>all</em> the options on the
2338 <directive>Options</directive> directive are preceded by a
2339 <code>+</code> or <code>-</code> symbol, the options are
2340 merged. Any options preceded by a <code>+</code> are added to the
2341 options currently in force, and any options preceded by a
2342 <code>-</code> are removed from the options currently in
2345 <note type="warning"><title>Warning</title>
2346 <p>Mixing <directive>Options</directive> with a <code>+</code> or
2347 <code>-</code> with those without is not valid syntax, and is likely
2348 to cause unexpected results.</p>
2351 <p>For example, without any <code>+</code> and <code>-</code> symbols:</p>
2354 <Directory /web/docs><br />
2356 Options Indexes FollowSymLinks<br />
2358 </Directory><br />
2360 <Directory /web/docs/spec><br />
2362 Options Includes<br />
2367 <p>then only <code>Includes</code> will be set for the
2368 <code>/web/docs/spec</code> directory. However if the second
2369 <directive>Options</directive> directive uses the <code>+</code> and
2370 <code>-</code> symbols:</p>
2373 <Directory /web/docs><br />
2375 Options Indexes FollowSymLinks<br />
2377 </Directory><br />
2379 <Directory /web/docs/spec><br />
2381 Options +Includes -Indexes<br />
2386 <p>then the options <code>FollowSymLinks</code> and
2387 <code>Includes</code> are set for the <code>/web/docs/spec</code>
2390 <note><title>Note</title>
2391 <p>Using <code>-IncludesNOEXEC</code> or
2392 <code>-Includes</code> disables server-side includes completely
2393 regardless of the previous setting.</p>
2396 <p>The default in the absence of any other settings is
2397 <code>All</code>.</p>
2399 </directivesynopsis>
2402 <name>RLimitCPU</name>
2403 <description>Limits the CPU consumption of processes launched
2404 by Apache children</description>
2405 <syntax>RLimitCPU <var>seconds</var>|max [<var>seconds</var>|max]</syntax>
2406 <default>Unset; uses operating system defaults</default>
2407 <contextlist><context>server config</context><context>virtual host</context>
2408 <context>directory</context><context>.htaccess</context></contextlist>
2409 <override>All</override>
2412 <p>Takes 1 or 2 parameters. The first parameter sets the soft
2413 resource limit for all processes and the second parameter sets
2414 the maximum resource limit. Either parameter can be a number,
2415 or <code>max</code> to indicate to the server that the limit should
2416 be set to the maximum allowed by the operating system
2417 configuration. Raising the maximum resource limit requires that
2418 the server is running as <code>root</code>, or in the initial startup
2421 <p>This applies to processes forked off from Apache children
2422 servicing requests, not the Apache children themselves. This
2423 includes CGI scripts and SSI exec commands, but not any
2424 processes forked off from the Apache parent such as piped
2427 <p>CPU resource limits are expressed in seconds per
2430 <seealso><directive module="core">RLimitMEM</directive></seealso>
2431 <seealso><directive module="core">RLimitNPROC</directive></seealso>
2432 </directivesynopsis>
2435 <name>RLimitMEM</name>
2436 <description>Limits the memory consumption of processes launched
2437 by Apache children</description>
2438 <syntax>RLimitMEM <var>bytes</var>|max [<var>bytes</var>|max]</syntax>
2439 <default>Unset; uses operating system defaults</default>
2440 <contextlist><context>server config</context><context>virtual host</context>
2441 <context>directory</context><context>.htaccess</context></contextlist>
2442 <override>All</override>
2445 <p>Takes 1 or 2 parameters. The first parameter sets the soft
2446 resource limit for all processes and the second parameter sets
2447 the maximum resource limit. Either parameter can be a number,
2448 or <code>max</code> to indicate to the server that the limit should
2449 be set to the maximum allowed by the operating system
2450 configuration. Raising the maximum resource limit requires that
2451 the server is running as <code>root</code>, or in the initial startup
2454 <p>This applies to processes forked off from Apache children
2455 servicing requests, not the Apache children themselves. This
2456 includes CGI scripts and SSI exec commands, but not any
2457 processes forked off from the Apache parent such as piped
2460 <p>Memory resource limits are expressed in bytes per
2463 <seealso><directive module="core">RLimitCPU</directive></seealso>
2464 <seealso><directive module="core">RLimitNPROC</directive></seealso>
2465 </directivesynopsis>
2468 <name>RLimitNPROC</name>
2469 <description>Limits the number of processes that can be launched by
2470 processes launched by Apache children</description>
2471 <syntax>RLimitNPROC <var>number</var>|max [<var>number</var>|max]</syntax>
2472 <default>Unset; uses operating system defaults</default>
2473 <contextlist><context>server config</context><context>virtual host</context>
2474 <context>directory</context><context>.htaccess</context></contextlist>
2475 <override>All</override>
2478 <p>Takes 1 or 2 parameters. The first parameter sets the soft
2479 resource limit for all processes and the second parameter sets
2480 the maximum resource limit. Either parameter can be a number,
2481 or <code>max</code> to indicate to the server that the limit
2482 should be set to the maximum allowed by the operating system
2483 configuration. Raising the maximum resource limit requires that
2484 the server is running as <code>root</code>, or in the initial startup
2487 <p>This applies to processes forked off from Apache children
2488 servicing requests, not the Apache children themselves. This
2489 includes CGI scripts and SSI exec commands, but not any
2490 processes forked off from the Apache parent such as piped
2493 <p>Process limits control the number of processes per user.</p>
2495 <note><title>Note</title>
2496 <p>If CGI processes are <strong>not</strong> running
2497 under user ids other than the web server user id, this directive
2498 will limit the number of processes that the server itself can
2499 create. Evidence of this situation will be indicated by
2500 <strong><code>cannot fork</code></strong> messages in the
2501 <code>error_log</code>.</p>
2504 <seealso><directive module="core">RLimitMEM</directive></seealso>
2505 <seealso><directive module="core">RLimitCPU</directive></seealso>
2506 </directivesynopsis>
2509 <name>ScriptInterpreterSource</name>
2510 <description>Technique for locating the interpreter for CGI
2511 scripts</description>
2512 <syntax>ScriptInterpreterSource Registry|Registry-Strict|Script</syntax>
2513 <default>ScriptInterpreterSource Script</default>
2514 <contextlist><context>server config</context><context>virtual host</context>
2515 <context>directory</context><context>.htaccess</context></contextlist>
2516 <override>FileInfo</override>
2517 <compatibility>Win32 only;
2518 option <code>Registry-Strict</code> is available in Apache 2.0 and
2519 later</compatibility>
2522 <p>This directive is used to control how Apache finds the
2523 interpreter used to run CGI scripts. The default setting is
2524 <code>Script</code>. This causes Apache to use the interpreter pointed to
2525 by the shebang line (first line, starting with <code>#!</code>) in the
2526 script. On Win32 systems this line usually looks like:</p>
2529 #!C:/Perl/bin/perl.exe
2532 <p>or, if <code>perl</code> is in the <code>PATH</code>, simply:</p>
2538 <p>Setting <code>ScriptInterpreterSource Registry</code> will
2539 cause the Windows Registry tree <code>HKEY_CLASSES_ROOT</code> to be
2540 searched using the script file extension (e.g., <code>.pl</code>) as a
2541 search key. The command defined by the registry subkey
2542 <code>Shell\ExecCGI\Command</code> or, if it does not exist, by the subkey
2543 <code>Shell\Open\Command</code> is used to open the script file. If the
2544 registry keys cannot be found, Apache falls back to the behavior of the
2545 <code>Script</code> option.</p>
2547 <note type="warning"><title>Security</title>
2548 <p>Be careful when using <code>ScriptInterpreterSource
2549 Registry</code> with <directive
2550 module="mod_alias">ScriptAlias</directive>'ed directories, because
2551 Apache will try to execute <strong>every</strong> file within this
2552 directory. The <code>Registry</code> setting may cause undesired
2553 program calls on files which are typically not executed. For
2554 example, the default open command on <code>.htm</code> files on
2555 most Windows systems will execute Microsoft Internet Explorer, so
2556 any HTTP request for an <code>.htm</code> file existing within the
2557 script directory would start the browser in the background on the
2558 server. This is a good way to crash your system within a minute or
2562 <p>The option <code>Registry-Strict</code> which is new in Apache
2563 2.0 does the same thing as <code>Registry</code> but uses only the
2564 subkey <code>Shell\ExecCGI\Command</code>. The
2565 <code>ExecCGI</code> key is not a common one. It must be
2566 configured manually in the windows registry and hence prevents
2567 accidental program calls on your system.</p>
2569 </directivesynopsis>
2572 <name>ServerAdmin</name>
2573 <description>Email address that the server includes in error
2574 messages sent to the client</description>
2575 <syntax>ServerAdmin <var>email-address</var>|<var>URL</var></syntax>
2576 <contextlist><context>server config</context><context>virtual host</context>
2580 <p>The <directive>ServerAdmin</directive> sets the contact address
2581 that the server includes in any error messages it returns to the
2582 client. If the <code>httpd</code> doesn't recognize the supplied argument
2584 assumes, that it's an <var>email-address</var> and prepends it with
2585 <code>mailto:</code> in hyperlink targets. However, it's recommended to
2586 actually use an email address, since there are a lot of CGI scripts that
2587 make that assumption. If you want to use an URL, it should point to another
2588 server under your control. Otherwise users may not be able to contact you in
2591 <p>It may be worth setting up a dedicated address for this, e.g.</p>
2594 ServerAdmin www-admin@foo.example.com
2596 <p>as users do not always mention that they are talking about the
2599 </directivesynopsis>
2602 <name>ServerAlias</name>
2603 <description>Alternate names for a host used when matching requests
2604 to name-virtual hosts</description>
2605 <syntax>ServerAlias <var>hostname</var> [<var>hostname</var>] ...</syntax>
2606 <contextlist><context>virtual host</context></contextlist>
2609 <p>The <directive>ServerAlias</directive> directive sets the
2610 alternate names for a host, for use with <a
2611 href="../vhosts/name-based.html">name-based virtual hosts</a>. The
2612 <directive>ServerAlias</directive> may include wildcards, if appropriate.</p>
2615 <VirtualHost *><br />
2616 ServerName server.domain.com<br />
2617 ServerAlias server server2.domain.com server2<br />
2619 </VirtualHost>
2622 <seealso><a href="../vhosts/">Apache Virtual Host documentation</a></seealso>
2623 </directivesynopsis>
2626 <name>ServerName</name>
2627 <description>Hostname and port that the server uses to identify
2628 itself</description>
2629 <syntax>ServerName [<var>scheme</var>://]<var>fully-qualified-domain-name</var>[:<var>port</var>]</syntax>
2630 <contextlist><context>server config</context><context>virtual host</context>
2632 <compatibility>In version 2.0, this
2633 directive supersedes the functionality of the <directive>Port</directive>
2634 directive from version 1.3.</compatibility>
2637 <p>The <directive>ServerName</directive> directive sets the
2638 request scheme, hostname and
2639 port that the server uses to identify itself. This is used when
2640 creating redirection URLs. For example, if the name of the
2641 machine hosting the web server is <code>simple.example.com</code>,
2642 but the machine also has the DNS alias <code>www.example.com</code>
2643 and you wish the web server to be so identified, the following
2644 directive should be used:</p>
2647 ServerName www.example.com:80
2650 <p>If no <directive>ServerName</directive> is specified, then the
2651 server attempts to deduce the hostname by performing a reverse
2652 lookup on the IP address. If no port is specified in the
2653 <directive>ServerName</directive>, then the server will use the
2654 port from the incoming request. For optimal reliability and
2655 predictability, you should specify an explicit hostname and port
2656 using the <directive>ServerName</directive> directive.</p>
2658 <p>If you are using <a
2659 href="../vhosts/name-based.html">name-based virtual hosts</a>,
2660 the <directive>ServerName</directive> inside a
2661 <directive type="section" module="core">VirtualHost</directive>
2662 section specifies what hostname must appear in the request's
2663 <code>Host:</code> header to match this virtual host.</p>
2666 <p>Sometimes, the server runs behind a device that processes SSL,
2667 such as a reverse proxy, load balancer or SSL offload
2668 appliance. When this is the case, specify the
2669 <code>https://</code> scheme and the port number to which the
2670 clients connect in the <directive>ServerName</directive> directive
2671 to make sure that the server generates the correct
2672 self-referential URLs.
2675 <p>See the description of the
2676 <directive module="core">UseCanonicalName</directive> and
2677 <directive module="core">UseCanonicalPhysicalPort</directive>directives for
2678 settings which determine whether self-referential URLs (e.g., by the
2679 <module>mod_dir</module> module) will refer to the
2680 specified port, or to the port number given in the client's request.
2685 <seealso><a href="../dns-caveats.html">Issues Regarding DNS and
2686 Apache</a></seealso>
2687 <seealso><a href="../vhosts/">Apache virtual host
2688 documentation</a></seealso>
2689 <seealso><directive module="core">UseCanonicalName</directive></seealso>
2690 <seealso><directive module="core">UseCanonicalPhysicalPort</directive></seealso>
2691 <seealso><directive module="core">NameVirtualHost</directive></seealso>
2692 <seealso><directive module="core">ServerAlias</directive></seealso>
2693 </directivesynopsis>
2696 <name>ServerPath</name>
2697 <description>Legacy URL pathname for a name-based virtual host that
2698 is accessed by an incompatible browser</description>
2699 <syntax>ServerPath <var>URL-path</var></syntax>
2700 <contextlist><context>virtual host</context></contextlist>
2703 <p>The <directive>ServerPath</directive> directive sets the legacy
2704 URL pathname for a host, for use with <a
2705 href="../vhosts/">name-based virtual hosts</a>.</p>
2707 <seealso><a href="../vhosts/">Apache Virtual Host documentation</a></seealso>
2708 </directivesynopsis>
2711 <name>ServerRoot</name>
2712 <description>Base directory for the server installation</description>
2713 <syntax>ServerRoot <var>directory-path</var></syntax>
2714 <default>ServerRoot /usr/local/apache</default>
2715 <contextlist><context>server config</context></contextlist>
2718 <p>The <directive>ServerRoot</directive> directive sets the
2719 directory in which the server lives. Typically it will contain the
2720 subdirectories <code>conf/</code> and <code>logs/</code>. Relative
2721 paths in other configuration directives (such as <directive
2722 module="core">Include</directive> or <directive
2723 module="mod_so">LoadModule</directive>, for example) are taken as
2724 relative to this directory.</p>
2726 <example><title>Example</title>
2727 ServerRoot /home/httpd
2731 <seealso><a href="../invoking.html">the <code>-d</code>
2732 option to <code>httpd</code></a></seealso>
2733 <seealso><a href="../misc/security_tips.html#serverroot">the
2734 security tips</a> for information on how to properly set
2735 permissions on the <directive>ServerRoot</directive></seealso>
2736 </directivesynopsis>
2739 <name>ServerSignature</name>
2740 <description>Configures the footer on server-generated documents</description>
2741 <syntax>ServerSignature On|Off|EMail</syntax>
2742 <default>ServerSignature Off</default>
2743 <contextlist><context>server config</context><context>virtual host</context>
2744 <context>directory</context><context>.htaccess</context>
2746 <override>All</override>
2749 <p>The <directive>ServerSignature</directive> directive allows the
2750 configuration of a trailing footer line under server-generated
2751 documents (error messages, <module>mod_proxy</module> ftp directory
2752 listings, <module>mod_info</module> output, ...). The reason why you
2753 would want to enable such a footer line is that in a chain of proxies,
2754 the user often has no possibility to tell which of the chained servers
2755 actually produced a returned error message.</p>
2757 <p>The <code>Off</code>
2758 setting, which is the default, suppresses the footer line (and is
2759 therefore compatible with the behavior of Apache-1.2 and
2760 below). The <code>On</code> setting simply adds a line with the
2761 server version number and <directive
2762 module="core">ServerName</directive> of the serving virtual host,
2763 and the <code>EMail</code> setting additionally creates a
2764 "mailto:" reference to the <directive
2765 module="core">ServerAdmin</directive> of the referenced
2768 <p>After version 2.0.44, the details of the server version number
2769 presented are controlled by the <directive
2770 module="core">ServerTokens</directive> directive.</p>
2772 <seealso><directive module="core">ServerTokens</directive></seealso>
2773 </directivesynopsis>
2776 <name>ServerTokens</name>
2777 <description>Configures the <code>Server</code> HTTP response
2778 header</description>
2779 <syntax>ServerTokens Major|Minor|Min[imal]|Prod[uctOnly]|OS|Full</syntax>
2780 <default>ServerTokens Full</default>
2781 <contextlist><context>server config</context></contextlist>
2784 <p>This directive controls whether <code>Server</code> response
2785 header field which is sent back to clients includes a
2786 description of the generic OS-type of the server as well as
2787 information about compiled-in modules.</p>
2790 <dt><code>ServerTokens Prod[uctOnly]</code></dt>
2792 <dd>Server sends (<em>e.g.</em>): <code>Server:
2795 <dt><code>ServerTokens Major</code></dt>
2797 <dd>Server sends (<em>e.g.</em>): <code>Server:
2798 Apache/2</code></dd>
2800 <dt><code>ServerTokens Minor</code></dt>
2802 <dd>Server sends (<em>e.g.</em>): <code>Server:
2803 Apache/2.0</code></dd>
2805 <dt><code>ServerTokens Min[imal]</code></dt>
2807 <dd>Server sends (<em>e.g.</em>): <code>Server:
2808 Apache/2.0.41</code></dd>
2810 <dt><code>ServerTokens OS</code></dt>
2812 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.0.41
2815 <dt><code>ServerTokens Full</code> (or not specified)</dt>
2817 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.0.41
2818 (Unix) PHP/4.2.2 MyMod/1.2</code></dd>
2821 <p>This setting applies to the entire server, and cannot be
2822 enabled or disabled on a virtualhost-by-virtualhost basis.</p>
2824 <p>After version 2.0.44, this directive also controls the
2825 information presented by the <directive
2826 module="core">ServerSignature</directive> directive.</p>
2828 <seealso><directive module="core">ServerSignature</directive></seealso>
2829 </directivesynopsis>
2832 <name>SetHandler</name>
2833 <description>Forces all matching files to be processed by a
2834 handler</description>
2835 <syntax>SetHandler <var>handler-name</var>|None</syntax>
2836 <contextlist><context>server config</context><context>virtual host</context>
2837 <context>directory</context><context>.htaccess</context>
2839 <override>FileInfo</override>
2840 <compatibility>Moved into the core in Apache 2.0</compatibility>
2843 <p>When placed into an <code>.htaccess</code> file or a
2844 <directive type="section" module="core">Directory</directive> or
2845 <directive type="section" module="core">Location</directive>
2846 section, this directive forces all matching files to be parsed
2847 through the <a href="../handler.html">handler</a> given by
2848 <var>handler-name</var>. For example, if you had a directory you
2849 wanted to be parsed entirely as imagemap rule files, regardless
2850 of extension, you might put the following into an
2851 <code>.htaccess</code> file in that directory:</p>
2854 SetHandler imap-file
2857 <p>Another example: if you wanted to have the server display a
2858 status report whenever a URL of
2859 <code>http://servername/status</code> was called, you might put
2860 the following into <code>httpd.conf</code>:</p>
2863 <Location /status><br />
2865 SetHandler server-status<br />
2870 <p>You can override an earlier defined <directive>SetHandler</directive>
2871 directive by using the value <code>None</code>.</p>
2872 <p><strong>Note:</strong> because SetHandler overrides default handlers,
2873 normal behaviour such as handling of URLs ending in a slash (/) as
2874 directories or index files is suppressed.</p>
2877 <seealso><directive module="mod_mime">AddHandler</directive></seealso>
2879 </directivesynopsis>
2882 <name>SetInputFilter</name>
2883 <description>Sets the filters that will process client requests and POST
2885 <syntax>SetInputFilter <var>filter</var>[;<var>filter</var>...]</syntax>
2886 <contextlist><context>server config</context><context>virtual host</context>
2887 <context>directory</context><context>.htaccess</context>
2889 <override>FileInfo</override>
2892 <p>The <directive>SetInputFilter</directive> directive sets the
2893 filter or filters which will process client requests and POST
2894 input when they are received by the server. This is in addition to
2895 any filters defined elsewhere, including the
2896 <directive module="mod_mime">AddInputFilter</directive>
2899 <p>If more than one filter is specified, they must be separated
2900 by semicolons in the order in which they should process the
2903 <seealso><a href="../filter.html">Filters</a> documentation</seealso>
2904 </directivesynopsis>
2907 <name>SetOutputFilter</name>
2908 <description>Sets the filters that will process responses from the
2909 server</description>
2910 <syntax>SetOutputFilter <var>filter</var>[;<var>filter</var>...]</syntax>
2911 <contextlist><context>server config</context><context>virtual host</context>
2912 <context>directory</context><context>.htaccess</context>
2914 <override>FileInfo</override>
2917 <p>The <directive>SetOutputFilter</directive> directive sets the filters
2918 which will process responses from the server before they are
2919 sent to the client. This is in addition to any filters defined
2920 elsewhere, including the
2921 <directive module="mod_mime">AddOutputFilter</directive>
2924 <p>For example, the following configuration will process all files
2925 in the <code>/www/data/</code> directory for server-side
2929 <Directory /www/data/><br />
2931 SetOutputFilter INCLUDES<br />
2936 <p>If more than one filter is specified, they must be separated
2937 by semicolons in the order in which they should process the
2940 <seealso><a href="../filter.html">Filters</a> documentation</seealso>
2941 </directivesynopsis>
2944 <name>TimeOut</name>
2945 <description>Amount of time the server will wait for
2946 certain events before failing a request</description>
2947 <syntax>TimeOut <var>seconds</var></syntax>
2948 <default>TimeOut 300</default>
2949 <contextlist><context>server config</context><context>virtual host</context></contextlist>
2952 <p>The <directive>TimeOut</directive> directive defines the length
2953 of time Apache will wait for I/O in various circumstances:</p>
2956 <li>When reading data from the client, the length of time to
2957 wait for a TCP packet to arrive if the read buffer is
2960 <li>When writing data to the client, the length of time to wait
2961 for an acknowledgement of a packet if the send buffer is
2964 <li>In <module>mod_cgi</module>, the length of time to wait for
2965 output from a CGI script.</li>
2967 <li>In <module>mod_ext_filter</module>, the length of time to
2968 wait for output from a filtering process.</li>
2970 <li>In <module>mod_proxy</module>, the default timeout value if
2971 <directive module="mod_proxy">ProxyTimeout</directive> is not
2976 </directivesynopsis>
2979 <name>TraceEnable</name>
2980 <description>Determines the behaviour on <code>TRACE</code>
2981 requests</description>
2982 <syntax>TraceEnable <var>[on|off|extended]</var></syntax>
2983 <default>TraceEnable on</default>
2984 <contextlist><context>server config</context></contextlist>
2985 <compatibility>Available in Apache 1.3.34, 2.0.55 and later</compatibility>
2988 <p>This directive overrides the behavior of <code>TRACE</code> for both
2989 the core server and <module>mod_proxy</module>. The default
2990 <code>TraceEnable on</code> permits <code>TRACE</code> requests per
2991 RFC 2616, which disallows any request body to accompany the request.
2992 <code>TraceEnable off</code> causes the core server and
2993 <module>mod_proxy</module> to return a <code>405</code> (Method not
2994 allowed) error to the client.</p>
2996 <p>Finally, for testing and diagnostic purposes only, request
2997 bodies may be allowed using the non-compliant <code>TraceEnable
2998 extended</code> directive. The core (as an origin server) will
2999 restrict the request body to 64k (plus 8k for chunk headers if
3000 <code>Transfer-Encoding: chunked</code> is used). The core will
3001 reflect the full headers and all chunk headers with the response
3002 body. As a proxy server, the request body is not restricted to 64k.</p>
3004 </directivesynopsis>
3007 <name>UseCanonicalName</name>
3008 <description>Configures how the server determines its own name and
3010 <syntax>UseCanonicalName On|Off|DNS</syntax>
3011 <default>UseCanonicalName Off</default>
3012 <contextlist><context>server config</context><context>virtual host</context>
3013 <context>directory</context></contextlist>
3016 <p>In many situations Apache must construct a <em>self-referential</em>
3017 URL -- that is, a URL that refers back to the same server. With
3018 <code>UseCanonicalName On</code> Apache will use the hostname and port
3019 specified in the <directive module="core">ServerName</directive>
3020 directive to construct the canonical name for the server. This name
3021 is used in all self-referential URLs, and for the values of
3022 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in CGIs.</p>
3024 <p>With <code>UseCanonicalName Off</code> Apache will form
3025 self-referential URLs using the hostname and port supplied by
3026 the client if any are supplied (otherwise it will use the
3027 canonical name, as defined above). These values are the same
3028 that are used to implement <a
3029 href="../vhosts/name-based.html">name based virtual hosts</a>,
3030 and are available with the same clients. The CGI variables
3031 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
3032 constructed from the client supplied values as well.</p>
3034 <p>An example where this may be useful is on an intranet server
3035 where you have users connecting to the machine using short
3036 names such as <code>www</code>. You'll notice that if the users
3037 type a shortname, and a URL which is a directory, such as
3038 <code>http://www/splat</code>, <em>without the trailing
3039 slash</em> then Apache will redirect them to
3040 <code>http://www.domain.com/splat/</code>. If you have
3041 authentication enabled, this will cause the user to have to
3042 authenticate twice (once for <code>www</code> and once again
3043 for <code>www.domain.com</code> -- see <a
3044 href="http://httpd.apache.org/docs/misc/FAQ.html#prompted-twice">the
3045 FAQ on this subject for more information</a>). But if
3046 <directive>UseCanonicalName</directive> is set <code>Off</code>, then
3047 Apache will redirect to <code>http://www/splat/</code>.</p>
3049 <p>There is a third option, <code>UseCanonicalName DNS</code>,
3050 which is intended for use with mass IP-based virtual hosting to
3051 support ancient clients that do not provide a
3052 <code>Host:</code> header. With this option Apache does a
3053 reverse DNS lookup on the server IP address that the client
3054 connected to in order to work out self-referential URLs.</p>
3056 <note type="warning"><title>Warning</title>
3057 <p>If CGIs make assumptions about the values of <code>SERVER_NAME</code>
3058 they may be broken by this option. The client is essentially free
3059 to give whatever value they want as a hostname. But if the CGI is
3060 only using <code>SERVER_NAME</code> to construct self-referential URLs
3061 then it should be just fine.</p>
3064 <seealso><directive module="core">UseCanonicalPhysicalPort</directive></seealso>
3065 <seealso><directive module="core">ServerName</directive></seealso>
3066 <seealso><directive module="mpm_common">Listen</directive></seealso>
3067 </directivesynopsis>
3070 <name>UseCanonicalPhysicalPort</name>
3071 <description>Configures how the server determines its own name and
3073 <syntax>UseCanonicalPhysicalPort On|Off</syntax>
3074 <default>UseCanonicalPhysicalPort Off</default>
3075 <contextlist><context>server config</context><context>virtual host</context>
3076 <context>directory</context></contextlist>
3079 <p>In many situations Apache must construct a <em>self-referential</em>
3080 URL -- that is, a URL that refers back to the same server. With
3081 <code>UseCanonicalPhysicalPort On</code> Apache will, when
3082 constructing the canonical port for the server to honor
3083 the <directive module="core">UseCanonicalName</directive> directive,
3084 provide the actual physical port number being used by this request
3085 as a potential port. With <code>UseCanonicalPhysicalPort Off</code>
3086 Apache will not ever use the actual physical port number, instead
3087 relying on all configured information to construct a valid port number.</p>
3089 <note><title>Note</title>
3090 <p>The ordering of when the physical port is used is as follows:<br /><br />
3091 <code>UseCanonicalName On</code></p>
3093 <li>Port provided in <code>Servername</code></li>
3094 <li>Physical port</li>
3095 <li>Default port</li>
3097 <code>UseCanonicalName Off | DNS</code>
3099 <li>Parsed port from <code>Host:</code> header</li>
3100 <li>Physical port</li>
3101 <li>Port provided in <code>Servername</code></li>
3102 <li>Default port</li>
3105 <p>With <code>UseCanonicalPhysicalPort Off</code>, the
3106 physical ports are removed from the ordering.</p>
3110 <seealso><directive module="core">UseCanonicalName</directive></seealso>
3111 <seealso><directive module="core">ServerName</directive></seealso>
3112 <seealso><directive module="mpm_common">Listen</directive></seealso>
3113 </directivesynopsis>
3115 <directivesynopsis type="section">
3116 <name>VirtualHost</name>
3117 <description>Contains directives that apply only to a specific
3118 hostname or IP address</description>
3119 <syntax><VirtualHost
3120 <var>addr</var>[:<var>port</var>] [<var>addr</var>[:<var>port</var>]]
3121 ...> ... </VirtualHost></syntax>
3122 <contextlist><context>server config</context></contextlist>
3125 <p><directive type="section">VirtualHost</directive> and
3126 <code></VirtualHost></code> are used to enclose a group of
3127 directives that will apply only to a particular virtual host. Any
3128 directive that is allowed in a virtual host context may be
3129 used. When the server receives a request for a document on a
3130 particular virtual host, it uses the configuration directives
3131 enclosed in the <directive type="section">VirtualHost</directive>
3132 section. <var>Addr</var> can be:</p>
3135 <li>The IP address of the virtual host;</li>
3137 <li>A fully qualified domain name for the IP address of the
3138 virtual host (not recommended);</li>
3140 <li>The character <code>*</code>, which is used only in combination with
3141 <code>NameVirtualHost *</code> to match all IP addresses; or</li>
3143 <li>The string <code>_default_</code>, which is used only
3144 with IP virtual hosting to catch unmatched IP addresses.</li>
3147 <example><title>Example</title>
3148 <VirtualHost 10.1.2.3><br />
3150 ServerAdmin webmaster@host.foo.com<br />
3151 DocumentRoot /www/docs/host.foo.com<br />
3152 ServerName host.foo.com<br />
3153 ErrorLog logs/host.foo.com-error_log<br />
3154 TransferLog logs/host.foo.com-access_log<br />
3156 </VirtualHost>
3160 <p>IPv6 addresses must be specified in square brackets because
3161 the optional port number could not be determined otherwise. An
3162 IPv6 example is shown below:</p>
3165 <VirtualHost [2001:db8::a00:20ff:fea7:ccea]><br />
3167 ServerAdmin webmaster@host.example.com<br />
3168 DocumentRoot /www/docs/host.example.com<br />
3169 ServerName host.example.com<br />
3170 ErrorLog logs/host.example.com-error_log<br />
3171 TransferLog logs/host.example.com-access_log<br />
3173 </VirtualHost>
3176 <p>Each Virtual Host must correspond to a different IP address,
3177 different port number or a different host name for the server,
3178 in the former case the server machine must be configured to
3179 accept IP packets for multiple addresses. (If the machine does
3180 not have multiple network interfaces, then this can be
3181 accomplished with the <code>ifconfig alias</code> command -- if
3182 your OS supports it).</p>
3184 <note><title>Note</title>
3185 <p>The use of <directive type="section">VirtualHost</directive> does
3186 <strong>not</strong> affect what addresses Apache listens on. You
3187 may need to ensure that Apache is listening on the correct addresses
3188 using <directive module="mpm_common">Listen</directive>.</p>
3191 <p>When using IP-based virtual hosting, the special name
3192 <code>_default_</code> can be specified in
3193 which case this virtual host will match any IP address that is
3194 not explicitly listed in another virtual host. In the absence
3195 of any <code>_default_</code> virtual host the "main" server config,
3196 consisting of all those definitions outside any VirtualHost
3197 section, is used when no IP-match occurs. (But note that any IP
3198 address that matches a <directive
3199 module="core">NameVirtualHost</directive> directive will use neither
3200 the "main" server config nor the <code>_default_</code> virtual host.
3201 See the <a href="../vhosts/name-based.html">name-based virtual hosting</a>
3202 documentation for further details.)</p>
3204 <p>You can specify a <code>:port</code> to change the port that is
3205 matched. If unspecified then it defaults to the same port as the
3206 most recent <directive module="mpm_common">Listen</directive>
3207 statement of the main server. You may also specify <code>:*</code>
3208 to match all ports on that address. (This is recommended when used
3209 with <code>_default_</code>.)</p>
3211 <p>A <directive module="core">ServerName</directive> should be
3212 specified inside each <directive
3213 type="section">VirtualHost</directive> block. If it is absent, the
3214 <directive module="core">ServerName</directive> from the "main"
3215 server configuration will be inherited.</p>
3217 <note type="warning"><title>Security</title>
3218 <p>See the <a href="../misc/security_tips.html">security tips</a>
3219 document for details on why your security could be compromised if the
3220 directory where log files are stored is writable by anyone other
3221 than the user that starts the server.</p>
3224 <seealso><a href="../vhosts/">Apache Virtual Host documentation</a></seealso>
3225 <seealso><a href="../dns-caveats.html">Issues Regarding DNS and
3226 Apache</a></seealso>
3227 <seealso><a href="../bind.html">Setting
3228 which addresses and ports Apache uses</a></seealso>
3229 <seealso><a href="../sections.html">How <Directory>, <Location>
3230 and <Files> sections work</a> for an explanation of how these
3231 different sections are combined when a request is received</seealso>
3232 </directivesynopsis>