2 <!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
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4 <!-- $LastChangedRevision$ -->
7 Copyright 2002-2005 The Apache Software Foundation or its licensors, as
10 Licensed under the Apache License, Version 2.0 (the "License");
11 you may not use this file except in compliance with the License.
12 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
17 distributed under the License is distributed on an "AS IS" BASIS,
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>AcceptPathInfo</name>
32 <description>Resources accept trailing pathname information</description>
33 <syntax>AcceptPathInfo On|Off|Default</syntax>
34 <default>AcceptPathInfo Default</default>
35 <contextlist><context>server config</context>
36 <context>virtual host</context><context>directory</context>
37 <context>.htaccess</context></contextlist>
38 <override>FileInfo</override>
39 <compatibility>Available in Apache 2.0.30 and later</compatibility>
43 <p>This directive controls whether requests that contain trailing
44 pathname information that follows an actual filename (or
45 non-existent file in an existing directory) will be accepted or
46 rejected. The trailing pathname information can be made
47 available to scripts in the <code>PATH_INFO</code> environment
50 <p>For example, assume the location <code>/test/</code> points to
51 a directory that contains only the single file
52 <code>here.html</code>. Then requests for
53 <code>/test/here.html/more</code> and
54 <code>/test/nothere.html/more</code> both collect
55 <code>/more</code> as <code>PATH_INFO</code>.</p>
57 <p>The three possible arguments for the
58 <directive>AcceptPathInfo</directive> directive are:</p>
60 <dt><code>Off</code></dt><dd>A request will only be accepted if it
61 maps to a literal path that exists. Therefore a request with
62 trailing pathname information after the true filename such as
63 <code>/test/here.html/more</code> in the above example will return
64 a 404 NOT FOUND error.</dd>
66 <dt><code>On</code></dt><dd>A request will be accepted if a
67 leading path component maps to a file that exists. The above
68 example <code>/test/here.html/more</code> will be accepted if
69 <code>/test/here.html</code> maps to a valid file.</dd>
71 <dt><code>Default</code></dt><dd>The treatment of requests with
72 trailing pathname information is determined by the <a
73 href="../handler.html">handler</a> responsible for the request.
74 The core handler for normal files defaults to rejecting
75 <code>PATH_INFO</code> requests. Handlers that serve scripts, such as <a
76 href="mod_cgi.html">cgi-script</a> and <a
77 href="mod_isapi.html">isapi-isa</a>, generally accept
78 <code>PATH_INFO</code> by default.</dd>
81 <p>The primary purpose of the <code>AcceptPathInfo</code>
82 directive is to allow you to override the handler's choice of
83 accepting or rejecting <code>PATH_INFO</code>. This override is required,
84 for example, when you use a <a href="../filter.html">filter</a>, such
85 as <a href="mod_include.html">INCLUDES</a>, to generate content
86 based on <code>PATH_INFO</code>. The core handler would usually reject
87 the request, so you can use the following configuration to enable
91 <Files "mypaths.shtml"><br />
93 Options +Includes<br />
94 SetOutputFilter INCLUDES<br />
95 AcceptPathInfo On<br />
104 <name>AccessFileName</name>
105 <description>Name of the distributed configuration file</description>
106 <syntax>AccessFileName <var>filename</var> [<var>filename</var>] ...</syntax>
107 <default>AccessFileName .htaccess</default>
108 <contextlist><context>server config</context><context>virtual host</context>
112 <p>While processing a request the server looks for
113 the first existing configuration file from this list of names in
114 every directory of the path to the document, if distributed
115 configuration files are <a href="#allowoverride">enabled for that
116 directory</a>. For example:</p>
122 <p>before returning the document
123 <code>/usr/local/web/index.html</code>, the server will read
124 <code>/.acl</code>, <code>/usr/.acl</code>,
125 <code>/usr/local/.acl</code> and <code>/usr/local/web/.acl</code>
126 for directives, unless they have been disabled with</p>
129 <Directory /><br />
131 AllowOverride None<br />
136 <seealso><directive module="core">AllowOverride</directive></seealso>
137 <seealso><a href="../configuring.html">Configuration Files</a></seealso>
138 <seealso><a href="../howto/htaccess.html">.htaccess Files</a></seealso>
142 <name>AddDefaultCharset</name>
143 <description>Default charset parameter to be added when a response
144 content-type is <code>text/plain</code> or <code>text/html</code></description>
145 <syntax>AddDefaultCharset On|Off|<var>charset</var></syntax>
146 <default>AddDefaultCharset Off</default>
147 <contextlist><context>server config</context>
148 <context>virtual host</context><context>directory</context>
149 <context>.htaccess</context></contextlist>
150 <override>FileInfo</override>
153 <p>This directive specifies a default value for the media type
154 charset parameter (the name of a character encoding) to be added
155 to a response if and only if the response's content-type is either
156 <code>text/plain</code> or <code>text/html</code>. This should override
157 any charset specified in the body of the response via a <code>META</code>
158 element, though the exact behavior is often dependent on the user's client
159 configuration. A setting of <code>AddDefaultCharset Off</code>
160 disables this functionality. <code>AddDefaultCharset On</code> enables
161 a default charset of <code>iso-8859-1</code>. Any other value is assumed
162 to be the <var>charset</var> to be used, which should be one of the
163 <a href="http://www.iana.org/assignments/character-sets">IANA registered
164 charset values</a> for use in MIME media types.
168 AddDefaultCharset utf-8
171 <p><directive>AddDefaultCharset</directive> should only be used when all
172 of the text resources to which it applies are known to be in that
173 character encoding and it is too inconvenient to label their charset
174 individually. One such example is to add the charset parameter
175 to resources containing generated content, such as legacy CGI
176 scripts, that might be vulnerable to cross-site scripting attacks
177 due to user-provided data being included in the output. Note, however,
178 that a better solution is to just fix (or delete) those scripts, since
179 setting a default charset does not protect users that have enabled
180 the "auto-detect character encoding" feature on their browser.</p>
182 <seealso><directive module="mod_mime">AddCharset</directive></seealso>
186 <name>AddOutputFilterByType</name>
187 <description>assigns an output filter to a particular MIME-type</description>
188 <syntax>AddOutputFilterByType <var>filter</var>[;<var>filter</var>...]
189 <var>MIME-type</var> [<var>MIME-type</var>] ...</syntax>
190 <contextlist><context>server config</context>
191 <context>virtual host</context><context>directory</context>
192 <context>.htaccess</context></contextlist>
193 <override>FileInfo</override>
194 <compatibility>Available in Apache 2.0.33 and later</compatibility>
197 <p>This directive activates a particular output <a
198 href="../filter.html">filter</a> for a request depending on the
199 response MIME-type.</p>
201 <p>The following example uses the <code>DEFLATE</code> filter, which
202 is provided by <module>mod_deflate</module>. It will compress all
203 output (either static or dynamic) which is labeled as
204 <code>text/html</code> or <code>text/plain</code> before it is sent
208 AddOutputFilterByType DEFLATE text/html text/plain
211 <p>If you want the content to be processed by more than one filter, their
212 names have to be separated by semicolons. It's also possible to use one
213 <directive>AddOutputFilterByType</directive> directive for each of
216 <p>The configuration below causes all script output labeled as
217 <code>text/html</code> to be processed at first by the
218 <code>INCLUDES</code> filter and then by the <code>DEFLATE</code>
222 <Location /cgi-bin/><br />
224 Options Includes<br />
225 AddOutputFilterByType INCLUDES;DEFLATE text/html<br />
230 <note type="warning"><title>Note</title>
231 <p>Enabling filters with <directive>AddOutputFilterByType</directive>
232 may fail partially or completely in some cases. For example, no
233 filters are applied if the MIME-type could not be determined and falls
234 back to the <directive module="core">DefaultType</directive> setting,
235 even if the <directive module="core">DefaultType</directive> is the
238 <p>However, if you want to make sure, that the filters will be
239 applied, assign the content type to a resource explicitly, for
240 example with <directive module="mod_mime">AddType</directive> or
241 <directive module="core">ForceType</directive>. Setting the
242 content type within a (non-nph) CGI script is also safe.</p>
244 <p>The by-type output filters are never applied on proxy requests.</p>
248 <seealso><directive module="mod_mime">AddOutputFilter</directive></seealso>
249 <seealso><directive module="core">SetOutputFilter</directive></seealso>
250 <seealso><a href="../filter.html">filters</a></seealso>
254 <name>AllowEncodedSlashes</name>
255 <description>Determines whether encoded path separators in URLs are allowed to
256 be passed through</description>
257 <syntax>AllowEncodedSlashes On|Off</syntax>
258 <default>AllowEncodedSlashes Off</default>
259 <contextlist><context>server config</context><context>virtual host</context>
261 <compatibility>Available in Apache 2.0.46 and later</compatibility>
264 <p>The <directive>AllowEncodedSlashes</directive> directive allows URLs
265 which contain encoded path separators (<code>%2F</code> for <code>/</code>
266 and additionally <code>%5C</code> for <code>\</code> on according systems)
267 to be used. Normally such URLs are refused with a 404 (Not found) error.</p>
269 <p>Turning <directive>AllowEncodedSlashes</directive> <code>On</code> is
270 mostly useful when used in conjunction with <code>PATH_INFO</code>.</p>
272 <note><title>Note</title>
273 <p>Allowing encoded slashes does <em>not</em> imply <em>decoding</em>.
274 Occurrences of <code>%2F</code> or <code>%5C</code> (<em>only</em> on
275 according systems) will be left as such in the otherwise decoded URL
279 <seealso><directive module="core">AcceptPathInfo</directive></seealso>
283 <name>AllowOverride</name>
284 <description>Types of directives that are allowed in
285 <code>.htaccess</code> files</description>
286 <syntax>AllowOverride All|None|<var>directive-type</var>
287 [<var>directive-type</var>] ...</syntax>
288 <default>AllowOverride All</default>
289 <contextlist><context>directory</context></contextlist>
292 <p>When the server finds an <code>.htaccess</code> file (as
293 specified by <directive module="core">AccessFileName</directive>)
294 it needs to know which directives declared in that file can override
295 earlier configuration directives.</p>
297 <note><title>Only available in <Directory> sections</title>
298 <directive>AllowOverride</directive> is valid only in
299 <directive type="section" module="core">Directory</directive>
300 sections specified without regular expressions, not in <directive
301 type="section" module="core">Location</directive>, <directive
302 module="core" type="section">DirectoryMatch</directive> or
303 <directive type="section" module="core">Files</directive> sections.
306 <p>When this directive is set to <code>None</code>, then
307 <a href="#accessfilename">.htaccess</a> files are completely ignored.
308 In this case, the server will not even attempt to read
309 <code>.htaccess</code> files in the filesystem.</p>
311 <p>When this directive is set to <code>All</code>, then any
312 directive which has the .htaccess <a
313 href="directive-dict.html#Context">Context</a> is allowed in
314 <code>.htaccess</code> files.</p>
316 <p>The <var>directive-type</var> can be one of the following
317 groupings of directives.</p>
324 Allow use of the authorization directives (<directive
325 module="mod_authn_dbm">AuthDBMGroupFile</directive>,
326 <directive module="mod_authn_dbm">AuthDBMUserFile</directive>,
327 <directive module="mod_authz_groupfile">AuthGroupFile</directive>,
328 <directive module="core">AuthName</directive>,
329 <directive module="core">AuthType</directive>, <directive
330 module="mod_authn_file">AuthUserFile</directive>, <directive
331 module="core">Require</directive>, <em>etc.</em>).</dd>
336 Allow use of the directives controlling document types (<directive
337 module="core">DefaultType</directive>, <directive
338 module="core">ErrorDocument</directive>, <directive
339 module="core">ForceType</directive>, <directive
340 module="mod_negotiation">LanguagePriority</directive>,
341 <directive module="core">SetHandler</directive>, <directive
342 module="core">SetInputFilter</directive>, <directive
343 module="core">SetOutputFilter</directive>, and
344 <module>mod_mime</module> Add* and Remove*
345 directives, <em>etc.</em>).</dd>
350 Allow use of the directives controlling directory indexing
352 module="mod_autoindex">AddDescription</directive>,
353 <directive module="mod_autoindex">AddIcon</directive>, <directive
354 module="mod_autoindex">AddIconByEncoding</directive>,
355 <directive module="mod_autoindex">AddIconByType</directive>,
356 <directive module="mod_autoindex">DefaultIcon</directive>, <directive
357 module="mod_dir">DirectoryIndex</directive>, <directive
358 module="mod_autoindex">FancyIndexing</directive>, <directive
359 module="mod_autoindex">HeaderName</directive>, <directive
360 module="mod_autoindex">IndexIgnore</directive>, <directive
361 module="mod_autoindex">IndexOptions</directive>, <directive
362 module="mod_autoindex">ReadmeName</directive>,
368 Allow use of the directives controlling host access (<directive
369 module="mod_authz_host">Allow</directive>, <directive
370 module="mod_authz_host">Deny</directive> and <directive
371 module="mod_authz_host">Order</directive>).</dd>
373 <dt>Options[=<var>Option</var>,...]</dt>
376 Allow use of the directives controlling specific directory
377 features (<directive module="core">Options</directive> and
378 <directive module="mod_include">XBitHack</directive>).
379 An equal sign may be given followed by a comma (but no spaces)
380 separated lists of options that may be set using the <directive
381 module="core">Options</directive> command.</dd>
387 AllowOverride AuthConfig Indexes
390 <p>In the example above all directives that are neither in the group
391 <code>AuthConfig</code> nor <code>Indexes</code> cause an internal
395 <seealso><directive module="core">AccessFileName</directive></seealso>
396 <seealso><a href="../configuring.html">Configuration Files</a></seealso>
397 <seealso><a href="../howto/htaccess.html">.htaccess Files</a></seealso>
401 <name>AuthName</name>
402 <description>Authorization realm for use in HTTP
403 authentication</description>
404 <syntax>AuthName <var>auth-domain</var></syntax>
405 <contextlist><context>directory</context><context>.htaccess</context>
407 <override>AuthConfig</override>
410 <p>This directive sets the name of the authorization realm for a
411 directory. This realm is given to the client so that the user
412 knows which username and password to send.
413 <directive>AuthName</directive> takes a single argument; if the
414 realm name contains spaces, it must be enclosed in quotation
415 marks. It must be accompanied by <directive
416 module="core">AuthType</directive> and <directive
417 module="core">Require</directive> directives, and directives such
418 as <directive module="mod_authn_file">AuthUserFile</directive> and
419 <directive module="mod_authz_groupfile">AuthGroupFile</directive> to
425 AuthName "Top Secret"
428 <p>The string provided for the <code>AuthName</code> is what will
429 appear in the password dialog provided by most browsers.</p>
432 href="../howto/auth.html">Authentication, Authorization, and
433 Access Control</a></seealso>
437 <name>AuthType</name>
438 <description>Type of user authentication</description>
439 <syntax>AuthType Basic|Digest</syntax>
440 <contextlist><context>directory</context><context>.htaccess</context>
442 <override>AuthConfig</override>
445 <p>This directive selects the type of user authentication for a
446 directory. Only <code>Basic</code> and <code>Digest</code> are
447 currently implemented.
449 It must be accompanied by <directive
450 module="core">AuthName</directive> and <directive
451 module="core">Require</directive> directives, and directives such
452 as <directive module="mod_authn_file">AuthUserFile</directive> and
453 <directive module="mod_authz_groupfile">AuthGroupFile</directive> to
456 <seealso><a href="../howto/auth.html">Authentication, Authorization,
457 and Access Control</a></seealso>
461 <name>CGIMapExtension</name>
462 <description>Technique for locating the interpreter for CGI
463 scripts</description>
464 <syntax>CGIMapExtension <var>cgi-path</var> <var>.extension</var></syntax>
465 <contextlist><context>directory</context><context>.htaccess</context>
467 <override>FileInfo</override>
468 <compatibility>NetWare only</compatibility>
471 <p>This directive is used to control how Apache finds the
472 interpreter used to run CGI scripts. For example, setting
473 <code>CGIMapExtension sys:\foo.nlm .foo</code> will
474 cause all CGI script files with a <code>.foo</code> extension to
475 be passed to the FOO interpreter.</p>
480 <name>ContentDigest</name>
481 <description>Enables the generation of <code>Content-MD5</code> HTTP Response
482 headers</description>
483 <syntax>ContentDigest On|Off</syntax>
484 <default>ContentDigest Off</default>
485 <contextlist><context>server config</context><context>virtual host</context>
486 <context>directory</context><context>.htaccess</context>
488 <override>Options</override>
489 <status>Experimental</status>
492 <p>This directive enables the generation of
493 <code>Content-MD5</code> headers as defined in RFC1864
494 respectively RFC2068.</p>
496 <p>MD5 is an algorithm for computing a "message digest"
497 (sometimes called "fingerprint") of arbitrary-length data, with
498 a high degree of confidence that any alterations in the data
499 will be reflected in alterations in the message digest.</p>
501 <p>The <code>Content-MD5</code> header provides an end-to-end
502 message integrity check (MIC) of the entity-body. A proxy or
503 client may check this header for detecting accidental
504 modification of the entity-body in transit. Example header:</p>
507 Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
510 <p>Note that this can cause performance problems on your server
511 since the message digest is computed on every request (the
512 values are not cached).</p>
514 <p><code>Content-MD5</code> is only sent for documents served
515 by the <module>core</module>, and not by any module. For example,
516 SSI documents, output from CGI scripts, and byte range responses
517 do not have this header.</p>
522 <name>DefaultType</name>
523 <description>MIME content-type that will be sent if the
524 server cannot determine a type in any other way</description>
525 <syntax>DefaultType <var>MIME-type</var></syntax>
526 <default>DefaultType text/plain</default>
527 <contextlist><context>server config</context><context>virtual host</context>
528 <context>directory</context><context>.htaccess</context>
530 <override>FileInfo</override>
533 <p>There will be times when the server is asked to provide a
534 document whose type cannot be determined by its MIME types
537 <p>The server must inform the client of the content-type of the
538 document, so in the event of an unknown type it uses the
539 <code>DefaultType</code>. For example:</p>
542 DefaultType image/gif
545 <p>would be appropriate for a directory which contained many GIF
546 images with filenames missing the <code>.gif</code> extension.</p>
548 <p>Note that unlike <directive
549 module="core">ForceType</directive>, this directive only
550 provides the default mime-type. All other mime-type definitions,
551 including filename extensions, that might identify the media type
552 will override this default.</p>
556 <directivesynopsis type="section">
557 <name>Directory</name>
558 <description>Enclose a group of directives that apply only to the
559 named file-system directory and sub-directories</description>
560 <syntax><Directory <var>directory-path</var>>
561 ... </Directory></syntax>
562 <contextlist><context>server config</context><context>virtual host</context>
566 <p><directive type="section">Directory</directive> and
567 <code></Directory></code> are used to enclose a group of
568 directives that will apply only to the named directory and
569 sub-directories of that directory. Any directive that is allowed
570 in a directory context may be used. <var>Directory-path</var> is
571 either the full path to a directory, or a wild-card string using
572 Unix shell-style matching. In a wild-card string, <code>?</code> matches
573 any single character, and <code>*</code> matches any sequences of
574 characters. You may also use <code>[]</code> character ranges. None
575 of the wildcards match a `/' character, so <code><Directory
576 /*/public_html></code> will not match
577 <code>/home/user/public_html</code>, but <code><Directory
578 /home/*/public_html></code> will match. Example:</p>
581 <Directory /usr/local/httpd/htdocs><br />
583 Options Indexes FollowSymLinks<br />
589 <p>Be careful with the <var>directory-path</var> arguments:
590 They have to literally match the filesystem path which Apache uses
591 to access the files. Directives applied to a particular
592 <code><Directory></code> will not apply to files accessed from
593 that same directory via a different path, such as via different symbolic
598 expressions can also be used, with the addition of the
599 <code>~</code> character. For example:</p>
602 <Directory ~ "^/www/.*/[0-9]{3}">
605 <p>would match directories in <code>/www/</code> that consisted of
608 <p>If multiple (non-regular expression) <directive
609 type="section">Directory</directive> sections
610 match the directory (or one of its parents) containing a document,
611 then the directives are applied in the order of shortest match
612 first, interspersed with the directives from the <a
613 href="#accessfilename">.htaccess</a> files. For example,
617 <Directory /><br />
619 AllowOverride None<br />
621 </Directory><br />
623 <Directory /home/><br />
625 AllowOverride FileInfo<br />
630 <p>for access to the document <code>/home/web/dir/doc.html</code>
634 <li>Apply directive <code>AllowOverride None</code>
635 (disabling <code>.htaccess</code> files).</li>
637 <li>Apply directive <code>AllowOverride FileInfo</code> (for
638 directory <code>/home</code>).</li>
640 <li>Apply any <code>FileInfo</code> directives in
641 <code>/home/.htaccess</code>, <code>/home/web/.htaccess</code> and
642 <code>/home/web/dir/.htaccess</code> in that order.</li>
645 <p>Regular expressions are not considered until after all of the
646 normal sections have been applied. Then all of the regular
647 expressions are tested in the order they appeared in the
648 configuration file. For example, with</p>
651 <Directory ~ abc$><br />
653 # ... directives here ...<br />
658 <p>the regular expression section won't be considered until after
659 all normal <directive type="section">Directory</directive>s and
660 <code>.htaccess</code> files have been applied. Then the regular
661 expression will match on <code>/home/abc/public_html/abc</code> and
662 the corresponding <directive type="section">Directory</directive> will
665 <p><strong>Note that the default Apache access for
666 <code><Directory /></code> is <code>Allow from All</code>.
667 This means that Apache will serve any file mapped from an URL. It is
668 recommended that you change this with a block such
672 <Directory /><br />
674 Order Deny,Allow<br />
680 <p><strong>and then override this for directories you
681 <em>want</em> accessible. See the <a
682 href="../misc/security_tips.html">Security Tips</a> page for more
683 details.</strong></p>
685 <p>The directory sections occur in the <code>httpd.conf</code> file.
686 <directive type="section">Directory</directive> directives
687 cannot nest, and cannot appear in a <directive module="core"
688 type="section">Limit</directive> or <directive module="core"
689 type="section">LimitExcept</directive> section.</p>
691 <seealso><a href="../sections.html">How <Directory>,
692 <Location> and <Files> sections work</a> for an
693 explanation of how these different sections are combined when a
694 request is received</seealso>
697 <directivesynopsis type="section">
698 <name>DirectoryMatch</name>
699 <description>Enclose directives that apply to
700 file-system directories matching a regular expression and their
701 subdirectories</description>
702 <syntax><DirectoryMatch <var>regex</var>>
703 ... </DirectoryMatch></syntax>
704 <contextlist><context>server config</context><context>virtual host</context>
708 <p><directive type="section">DirectoryMatch</directive> and
709 <code></DirectoryMatch></code> are used to enclose a group
710 of directives which will apply only to the named directory and
711 sub-directories of that directory, the same as <directive
712 module="core" type="section">Directory</directive>. However, it
713 takes as an argument a regular expression. For example:</p>
716 <DirectoryMatch "^/www/(.+/)?[0-9]{3}">
719 <p>would match directories in <code>/www/</code> that consisted of three
722 <seealso><directive type="section" module="core">Directory</directive> for
723 a description of how regular expressions are mixed in with normal
724 <directive type="section">Directory</directive>s</seealso>
726 href="../sections.html">How <Directory>, <Location> and
727 <Files> sections work</a> for an explanation of how these different
728 sections are combined when a request is received</seealso>
732 <name>DocumentRoot</name>
733 <description>Directory that forms the main document tree visible
734 from the web</description>
735 <syntax>DocumentRoot <var>directory-path</var></syntax>
736 <default>DocumentRoot /usr/local/apache/htdocs</default>
737 <contextlist><context>server config</context><context>virtual host</context>
741 <p>This directive sets the directory from which <program>httpd</program>
742 will serve files. Unless matched by a directive like <directive
743 module="mod_alias">Alias</directive>, the server appends the
744 path from the requested URL to the document root to make the
745 path to the document. Example:</p>
748 DocumentRoot /usr/web
752 <code>http://www.my.host.com/index.html</code> refers to
753 <code>/usr/web/index.html</code>. If the <var>directory-path</var> is
754 not absolute then it is assumed to be relative to the <directive
755 module="core">ServerRoot</directive>.</p>
757 <p>The <directive>DocumentRoot</directive> should be specified without
758 a trailing slash.</p>
760 <seealso><a href="../urlmapping.html">Mapping URLs to Filesystem
761 Location</a></seealso>
765 <name>EnableMMAP</name>
766 <description>Use memory-mapping to read files during delivery</description>
767 <syntax>EnableMMAP On|Off</syntax>
768 <default>EnableMMAP On</default>
769 <contextlist><context>server config</context><context>virtual host</context>
770 <context>directory</context><context>.htaccess</context>
772 <override>FileInfo</override>
775 <p>This directive controls whether the <program>httpd</program> may use
776 memory-mapping if it needs to read the contents of a file during
777 delivery. By default, when the handling of a request requires
778 access to the data within a file -- for example, when delivering a
779 server-parsed file using <module>mod_include</module> -- Apache
780 memory-maps the file if the OS supports it.</p>
782 <p>This memory-mapping sometimes yields a performance improvement.
783 But in some environments, it is better to disable the memory-mapping
784 to prevent operational problems:</p>
787 <li>On some multiprocessor systems, memory-mapping can reduce the
788 performance of the <program>httpd</program>.</li>
789 <li>With an NFS-mounted <directive module="core">DocumentRoot</directive>,
790 the <program>httpd</program> may crash due to a segmentation fault if a file
791 is deleted or truncated while the <program>httpd</program> has it
795 <p>For server configurations that are vulnerable to these problems,
796 you should disable memory-mapping of delivered files by specifying:</p>
802 <p>For NFS mounted files, this feature may be disabled explicitly for
803 the offending files by specifying:</p>
806 <Directory "/path-to-nfs-files">
816 <name>EnableSendfile</name>
817 <description>Use the kernel sendfile support to deliver files to the client</description>
818 <syntax>EnableSendfile On|Off</syntax>
819 <default>EnableSendfile On</default>
820 <contextlist><context>server config</context><context>virtual host</context>
821 <context>directory</context><context>.htaccess</context>
823 <override>FileInfo</override>
824 <compatibility>Available in version 2.0.44 and later</compatibility>
827 <p>This directive controls whether <program>httpd</program> may use the
828 sendfile support from the kernel to transmit file contents to the client.
829 By default, when the handling of a request requires no access
830 to the data within a file -- for example, when delivering a
831 static file -- Apache uses sendfile to deliver the file contents
832 without ever reading the file if the OS supports it.</p>
834 <p>This sendfile mechanism avoids separate read and send operations,
835 and buffer allocations. But on some platforms or within some
836 filesystems, it is better to disable this feature to avoid
837 operational problems:</p>
840 <li>Some platforms may have broken sendfile support that the build
841 system did not detect, especially if the binaries were built on
842 another box and moved to such a machine with broken sendfile
844 <li>On Linux the use of sendfile triggers TCP-checksum
845 offloading bugs on certain networking cards when using IPv6.</li>
846 <li>With a network-mounted <directive
847 module="core">DocumentRoot</directive> (e.g., NFS or SMB),
848 the kernel may be unable to serve the network file through
852 <p>For server configurations that are vulnerable to these problems,
853 you should disable this feature by specifying:</p>
859 <p>For NFS or SMB mounted files, this feature may be disabled explicitly
860 for the offending files by specifying:</p>
863 <Directory "/path-to-nfs-files">
873 <name>ErrorDocument</name>
874 <description>What the server will return to the client
875 in case of an error</description>
876 <syntax>ErrorDocument <var>error-code</var> <var>document</var></syntax>
877 <contextlist><context>server config</context><context>virtual host</context>
878 <context>directory</context><context>.htaccess</context>
880 <override>FileInfo</override>
881 <compatibility>Quoting syntax for text messages is different in Apache
885 <p>In the event of a problem or error, Apache can be configured
886 to do one of four things,</p>
889 <li>output a simple hardcoded error message</li>
891 <li>output a customized message</li>
893 <li>redirect to a local <var>URL-path</var> to handle the
896 <li>redirect to an external <var>URL</var> to handle the
900 <p>The first option is the default, while options 2-4 are
901 configured using the <directive>ErrorDocument</directive>
902 directive, which is followed by the HTTP response code and a URL
903 or a message. Apache will sometimes offer additional information
904 regarding the problem/error.</p>
906 <p>URLs can begin with a slash (/) for local URLs, or be a full
907 URL which the client can resolve. Alternatively, a message can
908 be provided to be displayed by the browser. Examples:</p>
911 ErrorDocument 500 http://foo.example.com/cgi-bin/tester<br />
912 ErrorDocument 404 /cgi-bin/bad_urls.pl<br />
913 ErrorDocument 401 /subscription_info.html<br />
914 ErrorDocument 403 "Sorry can't allow you access today"
917 <p>Additionally, the special value <code>default</code> can be used
918 to specify Apache's simple hardcoded message. While not required
919 under normal circumstances, <code>default</code> will restore
920 Apache's simple hardcoded message for configurations that would
921 otherwise inherit an existing <directive>ErrorDocument</directive>.</p>
924 ErrorDocument 404 /cgi-bin/bad_urls.pl<br /><br />
925 <Directory /web/docs><br />
927 ErrorDocument 404 default<br />
932 <p>Note that when you specify an <directive>ErrorDocument</directive>
933 that points to a remote URL (ie. anything with a method such as
934 <code>http</code> in front of it), Apache will send a redirect to the
935 client to tell it where to find the document, even if the
936 document ends up being on the same server. This has several
937 implications, the most important being that the client will not
938 receive the original error status code, but instead will
939 receive a redirect status code. This in turn can confuse web
940 robots and other clients which try to determine if a URL is
941 valid using the status code. In addition, if you use a remote
942 URL in an <code>ErrorDocument 401</code>, the client will not
943 know to prompt the user for a password since it will not
944 receive the 401 status code. Therefore, <strong>if you use an
945 <code>ErrorDocument 401</code> directive then it must refer to a local
946 document.</strong></p>
948 <p>Microsoft Internet Explorer (MSIE) will by default ignore
949 server-generated error messages when they are "too small" and substitute
950 its own "friendly" error messages. The size threshold varies depending on
951 the type of error, but in general, if you make your error document
952 greater than 512 bytes, then MSIE will show the server-generated
953 error rather than masking it. More information is available in
954 Microsoft Knowledge Base article <a
955 href="http://support.microsoft.com/default.aspx?scid=kb;en-us;Q294807"
958 <p>Prior to version 2.0, messages were indicated by prefixing
959 them with a single unmatched double quote character.</p>
962 <seealso><a href="../custom-error.html">documentation of
963 customizable responses</a></seealso>
967 <name>ErrorLog</name>
968 <description>Location where the server will log errors</description>
969 <syntax> ErrorLog <var>file-path</var>|syslog[:<var>facility</var>]</syntax>
970 <default>ErrorLog logs/error_log (Unix) ErrorLog logs/error.log (Windows and OS/2)</default>
971 <contextlist><context>server config</context><context>virtual host</context>
975 <p>The <directive>ErrorLog</directive> directive sets the name of
976 the file to which the server will log any errors it encounters. If
977 the <var>file-path</var> is not absolute then it is assumed to be
978 relative to the <directive module="core">ServerRoot</directive>.</p>
980 <example><title>Example</title>
981 ErrorLog /var/log/httpd/error_log
984 <p>If the <var>file-path</var>
985 begins with a pipe (|) then it is assumed to be a command to spawn
986 to handle the error log.</p>
988 <example><title>Example</title>
989 ErrorLog "|/usr/local/bin/httpd_errors"
992 <p>Using <code>syslog</code> instead of a filename enables logging
993 via syslogd(8) if the system supports it. The default is to use
994 syslog facility <code>local7</code>, but you can override this by
995 using the <code>syslog:<var>facility</var></code> syntax where
996 <var>facility</var> can be one of the names usually documented in
999 <example><title>Example</title>
1000 ErrorLog syslog:user
1003 <p>SECURITY: See the <a
1004 href="../misc/security_tips.html#serverroot">security tips</a>
1005 document for details on why your security could be compromised
1006 if the directory where log files are stored is writable by
1007 anyone other than the user that starts the server.</p>
1008 <note type="warning"><title>Note</title>
1009 <p>When entering a file path on non-Unix platforms, care should be taken
1010 to make sure that only forward slashed are used even though the platform
1011 may allow the use of back slashes. In general it is a good idea to always
1012 use forward slashes throughout the configuration files.</p>
1015 <seealso><directive module="core">LogLevel</directive></seealso>
1016 <seealso><a href="../logs.html">Apache Log Files</a></seealso>
1017 </directivesynopsis>
1020 <name>FileETag</name>
1021 <description>File attributes used to create the ETag
1022 HTTP response header</description>
1023 <syntax>FileETag <var>component</var> ...</syntax>
1024 <default>FileETag INode MTime Size</default>
1025 <contextlist><context>server config</context><context>virtual host</context>
1026 <context>directory</context><context>.htaccess</context>
1028 <override>FileInfo</override>
1032 The <directive>FileETag</directive> directive configures the file
1033 attributes that are used to create the <code>ETag</code> (entity
1034 tag) response header field when the document is based on a file.
1035 (The <code>ETag</code> value is used in cache management to save
1036 network bandwidth.) In Apache 1.3.22 and earlier, the
1037 <code>ETag</code> value was <em>always</em> formed
1038 from the file's inode, size, and last-modified time (mtime). The
1039 <directive>FileETag</directive> directive allows you to choose
1040 which of these -- if any -- should be used. The recognized keywords are:
1044 <dt><strong>INode</strong></dt>
1045 <dd>The file's i-node number will be included in the calculation</dd>
1046 <dt><strong>MTime</strong></dt>
1047 <dd>The date and time the file was last modified will be included</dd>
1048 <dt><strong>Size</strong></dt>
1049 <dd>The number of bytes in the file will be included</dd>
1050 <dt><strong>All</strong></dt>
1051 <dd>All available fields will be used. This is equivalent to:
1052 <example>FileETag INode MTime Size</example></dd>
1053 <dt><strong>None</strong></dt>
1054 <dd>If a document is file-based, no <code>ETag</code> field will be
1055 included in the response</dd>
1058 <p>The <code>INode</code>, <code>MTime</code>, and <code>Size</code>
1059 keywords may be prefixed with either <code>+</code> or <code>-</code>,
1060 which allow changes to be made to the default setting inherited
1061 from a broader scope. Any keyword appearing without such a prefix
1062 immediately and completely cancels the inherited setting.</p>
1064 <p>If a directory's configuration includes
1065 <code>FileETag INode MTime Size</code>, and a
1066 subdirectory's includes <code>FileETag -INode</code>,
1067 the setting for that subdirectory (which will be inherited by
1068 any sub-subdirectories that don't override it) will be equivalent to
1069 <code>FileETag MTime Size</code>.</p>
1071 </directivesynopsis>
1073 <directivesynopsis type="section">
1075 <description>Contains directives that apply to matched
1076 filenames</description>
1077 <syntax><Files <var>filename</var>> ... </Files></syntax>
1078 <contextlist><context>server config</context><context>virtual host</context>
1079 <context>directory</context><context>.htaccess</context>
1081 <override>All</override>
1084 <p>The <directive type="section">Files</directive> directive
1085 limits the scope of the enclosed directives by filename. It is comparable
1086 to the <directive module="core" type="section">Directory</directive>
1087 and <directive module="core" type="section">Location</directive>
1088 directives. It should be matched with a <code></Files></code>
1089 directive. The directives given within this section will be applied to
1090 any object with a basename (last component of filename) matching the
1091 specified filename. <directive type="section">Files</directive>
1092 sections are processed in the order they appear in the
1093 configuration file, after the <directive module="core"
1094 type="section">Directory</directive> sections and
1095 <code>.htaccess</code> files are read, but before <directive
1096 type="section" module="core">Location</directive> sections. Note
1097 that <directive type="section">Files</directive> can be nested
1098 inside <directive type="section"
1099 module="core">Directory</directive> sections to restrict the
1100 portion of the filesystem they apply to.</p>
1102 <p>The <var>filename</var> argument should include a filename, or
1103 a wild-card string, where <code>?</code> matches any single character,
1104 and <code>*</code> matches any sequences of characters. Extended regular
1105 expressions can also be used, with the addition of the
1106 <code>~</code> character. For example:</p>
1109 <Files ~ "\.(gif|jpe?g|png)$">
1112 <p>would match most common Internet graphics formats. <directive
1113 module="core" type="section">FilesMatch</directive> is preferred,
1116 <p>Note that unlike <directive type="section"
1117 module="core">Directory</directive> and <directive type="section"
1118 module="core">Location</directive> sections, <directive
1119 type="section">Files</directive> sections can be used inside
1120 <code>.htaccess</code> files. This allows users to control access to
1121 their own files, at a file-by-file level.</p>
1124 <seealso><a href="../sections.html">How <Directory>, <Location>
1125 and <Files> sections work</a> for an explanation of how these
1126 different sections are combined when a request is received</seealso>
1127 </directivesynopsis>
1129 <directivesynopsis type="section">
1130 <name>FilesMatch</name>
1131 <description>Contains directives that apply to regular-expression matched
1132 filenames</description>
1133 <syntax><FilesMatch <var>regex</var>> ... </FilesMatch></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">FilesMatch</directive> directive
1141 limits the scope of the enclosed directives by filename, just as the
1142 <directive module="core" type="section">Files</directive> directive
1143 does. However, it accepts a regular expression. For example:</p>
1146 <FilesMatch "\.(gif|jpe?g|png)$">
1149 <p>would match most common Internet graphics formats.</p>
1152 <seealso><a href="../sections.html">How <Directory>, <Location>
1153 and <Files> sections work</a> for an explanation of how these
1154 different sections are combined when a request is received</seealso>
1155 </directivesynopsis>
1158 <name>ForceType</name>
1159 <description>Forces all matching files to be served with the specified
1160 MIME content-type</description>
1161 <syntax>ForceType <var>MIME-type</var>|None</syntax>
1162 <contextlist><context>directory</context><context>.htaccess</context>
1164 <override>FileInfo</override>
1165 <compatibility>Moved to the core in Apache 2.0</compatibility>
1168 <p>When placed into an <code>.htaccess</code> file or a
1169 <directive type="section" module="core">Directory</directive>, or
1170 <directive type="section" module="core">Location</directive> or
1171 <directive type="section" module="core">Files</directive>
1172 section, this directive forces all matching files to be served
1173 with the content type identification given by
1174 <var>MIME-type</var>. For example, if you had a directory full of
1175 GIF files, but did not want to label them all with <code>.gif</code>,
1176 you might want to use:</p>
1182 <p>Note that unlike <directive module="core">DefaultType</directive>,
1183 this directive overrides all mime-type associations, including
1184 filename extensions, that might identify the media type.</p>
1186 <p>You can override any <directive>ForceType</directive> setting
1187 by using the value of <code>None</code>:</p>
1190 # force all files to be image/gif:<br />
1191 <Location /images><br />
1193 ForceType image/gif<br />
1195 </Location><br />
1197 # but normal mime-type associations here:<br />
1198 <Location /images/mixed><br />
1200 ForceType None<br />
1205 </directivesynopsis>
1208 <name>HostnameLookups</name>
1209 <description>Enables DNS lookups on client IP addresses</description>
1210 <syntax>HostnameLookups On|Off|Double</syntax>
1211 <default>HostnameLookups Off</default>
1212 <contextlist><context>server config</context><context>virtual host</context>
1213 <context>directory</context></contextlist>
1216 <p>This directive enables DNS lookups so that host names can be
1217 logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
1218 The value <code>Double</code> refers to doing double-reverse
1219 DNS lookup. That is, after a reverse lookup is performed, a forward
1220 lookup is then performed on that result. At least one of the IP
1221 addresses in the forward lookup must match the original
1222 address. (In "tcpwrappers" terminology this is called
1223 <code>PARANOID</code>.)</p>
1225 <p>Regardless of the setting, when <module>mod_authz_host</module> is
1226 used for controlling access by hostname, a double reverse lookup
1227 will be performed. This is necessary for security. Note that the
1228 result of this double-reverse isn't generally available unless you
1229 set <code>HostnameLookups Double</code>. For example, if only
1230 <code>HostnameLookups On</code> and a request is made to an object
1231 that is protected by hostname restrictions, regardless of whether
1232 the double-reverse fails or not, CGIs will still be passed the
1233 single-reverse result in <code>REMOTE_HOST</code>.</p>
1235 <p>The default is <code>Off</code> in order to save the network
1236 traffic for those sites that don't truly need the reverse
1237 lookups done. It is also better for the end users because they
1238 don't have to suffer the extra latency that a lookup entails.
1239 Heavily loaded sites should leave this directive
1240 <code>Off</code>, since DNS lookups can take considerable
1241 amounts of time. The utility <program>logresolve</program>, compiled by
1242 default to the <code>bin</code> subdirectory of your installation
1243 directory, can be used to look up host names from logged IP addresses
1246 </directivesynopsis>
1248 <directivesynopsis type="section">
1249 <name>IfDefine</name>
1250 <description>Encloses directives that will be processed only
1251 if a test is true at startup</description>
1252 <syntax><IfDefine [!]<var>parameter-name</var>> ...
1253 </IfDefine></syntax>
1254 <contextlist><context>server config</context><context>virtual host</context>
1255 <context>directory</context><context>.htaccess</context>
1257 <override>All</override>
1260 <p>The <code><IfDefine <var>test</var>>...</IfDefine>
1261 </code> section is used to mark directives that are conditional. The
1262 directives within an <directive type="section">IfDefine</directive>
1263 section are only processed if the <var>test</var> is true. If <var>
1264 test</var> is false, everything between the start and end markers is
1267 <p>The <var>test</var> in the <directive type="section"
1268 >IfDefine</directive> section directive can be one of two forms:</p>
1271 <li><var>parameter-name</var></li>
1273 <li><code>!</code><var>parameter-name</var></li>
1276 <p>In the former case, the directives between the start and end
1277 markers are only processed if the parameter named
1278 <var>parameter-name</var> is defined. The second format reverses
1279 the test, and only processes the directives if
1280 <var>parameter-name</var> is <strong>not</strong> defined.</p>
1282 <p>The <var>parameter-name</var> argument is a define as given on
1283 the <program>httpd</program> command line via <code>-D<var>parameter-</var>
1284 </code>, at the time the server was started.</p>
1286 <p><directive type="section">IfDefine</directive> sections are
1287 nest-able, which can be used to implement simple
1288 multiple-parameter tests. Example:</p>
1291 httpd -DReverseProxy ...<br />
1294 <IfDefine ReverseProxy><br />
1296 LoadModule rewrite_module modules/mod_rewrite.so<br />
1297 LoadModule proxy_module modules/libproxy.so<br />
1302 </directivesynopsis>
1304 <directivesynopsis type="section">
1305 <name>IfModule</name>
1306 <description>Encloses directives that are processed conditional on the
1307 presence or absence of a specific module</description>
1308 <syntax><IfModule [!]<var>module-file</var>|<var>module-identifier</var>> ...
1309 </IfModule></syntax>
1310 <contextlist><context>server config</context><context>virtual host</context>
1311 <context>directory</context><context>.htaccess</context>
1313 <override>All</override>
1314 <compatibility>Module identifiers are available in version 2.1 and
1315 later.</compatibility>
1318 <p>The <code><IfModule <var>test</var>>...</IfModule></code>
1319 section is used to mark directives that are conditional on the presence of
1320 a specific module. The directives within an <directive type="section"
1321 >IfModule</directive> section are only processed if the <var>test</var>
1322 is true. If <var>test</var> is false, everything between the start and
1323 end markers is ignored.</p>
1325 <p>The <var>test</var> in the <directive type="section"
1326 >IfModule</directive> section directive can be one of two forms:</p>
1329 <li><var>module</var></li>
1331 <li>!<var>module</var></li>
1334 <p>In the former case, the directives between the start and end
1335 markers are only processed if the module named <var>module</var>
1336 is included in Apache -- either compiled in or
1337 dynamically loaded using <directive module="mod_so"
1338 >LoadModule</directive>. The second format reverses the test,
1339 and only processes the directives if <var>module</var> is
1340 <strong>not</strong> included.</p>
1342 <p>The <var>module</var> argument can be either the module identifier or
1343 the file name of the module, at the time it was compiled. For example,
1344 <code>rewrite_module</code> is the identifier and
1345 <code>mod_rewrite.c</code> is the file name. If a module consists of
1346 several source files, use the name of the file containing the string
1347 <code>STANDARD20_MODULE_STUFF</code>.</p>
1349 <p><directive type="section">IfModule</directive> sections are
1350 nest-able, which can be used to implement simple multiple-module
1353 <note>This section should only be used if you need to have one
1354 configuration file that works whether or not a specific module
1355 is available. In normal operation, directives need not be
1356 placed in <directive type="section">IfModule</directive>
1359 </directivesynopsis>
1362 <name>Include</name>
1363 <description>Includes other configuration files from within
1364 the server configuration files</description>
1365 <syntax>Include <var>file-path</var>|<var>directory-path</var></syntax>
1366 <contextlist><context>server config</context><context>virtual host</context>
1367 <context>directory</context>
1369 <compatibility>Wildcard matching available in 2.0.41 and later</compatibility>
1372 <p>This directive allows inclusion of other configuration files
1373 from within the server configuration files.</p>
1375 <p>Shell-style (<code>fnmatch()</code>) wildcard characters can be used to
1376 include several files at once, in alphabetical order. In
1377 addition, if <directive>Include</directive> points to a directory,
1378 rather than a file, Apache will read all files in that directory
1379 and any subdirectory. But including entire directories is not
1380 recommended, because it is easy to accidentally leave temporary
1381 files in a directory that can cause <program>httpd</program> to
1384 <p>The file path specified may be an absolute path, or may be relative
1385 to the <directive module="core">ServerRoot</directive> directory.</p>
1390 Include /usr/local/apache2/conf/ssl.conf<br />
1391 Include /usr/local/apache2/conf/vhosts/*.conf
1394 <p>Or, providing paths relative to your <directive
1395 module="core">ServerRoot</directive> directory:</p>
1398 Include conf/ssl.conf<br />
1399 Include conf/vhosts/*.conf
1402 <p>Running <code>apachectl configtest</code> will give you a list
1403 of the files that are being processed during the configuration
1407 root@host# apachectl configtest<br />
1408 Processing config file: /usr/local/apache2/conf/ssl.conf<br />
1409 Processing config file: /usr/local/apache2/conf/vhosts/vhost1.conf<br />
1410 Processing config file: /usr/local/apache2/conf/vhosts/vhost2.conf<br />
1415 <seealso><program>apachectl</program></seealso>
1416 </directivesynopsis>
1419 <name>KeepAlive</name>
1420 <description>Enables HTTP persistent connections</description>
1421 <syntax>KeepAlive On|Off</syntax>
1422 <default>KeepAlive On</default>
1423 <contextlist><context>server config</context><context>virtual host</context>
1427 <p>The Keep-Alive extension to HTTP/1.0 and the persistent
1428 connection feature of HTTP/1.1 provide long-lived HTTP sessions
1429 which allow multiple requests to be sent over the same TCP
1430 connection. In some cases this has been shown to result in an
1431 almost 50% speedup in latency times for HTML documents with
1432 many images. To enable Keep-Alive connections, set
1433 <code>KeepAlive On</code>.</p>
1435 <p>For HTTP/1.0 clients, Keep-Alive connections will only be
1436 used if they are specifically requested by a client. In
1437 addition, a Keep-Alive connection with an HTTP/1.0 client can
1438 only be used when the length of the content is known in
1439 advance. This implies that dynamic content such as CGI output,
1440 SSI pages, and server-generated directory listings will
1441 generally not use Keep-Alive connections to HTTP/1.0 clients.
1442 For HTTP/1.1 clients, persistent connections are the default
1443 unless otherwise specified. If the client requests it, chunked
1444 encoding will be used in order to send content of unknown
1445 length over persistent connections.</p>
1448 <seealso><directive module="core">MaxKeepAliveRequests</directive></seealso>
1449 </directivesynopsis>
1452 <name>KeepAliveTimeout</name>
1453 <description>Amount of time the server will wait for subsequent
1454 requests on a persistent connection</description>
1455 <syntax>KeepAliveTimeout <var>seconds</var></syntax>
1456 <default>KeepAliveTimeout 15</default>
1457 <contextlist><context>server config</context><context>virtual host</context>
1461 <p>The number of seconds Apache will wait for a subsequent
1462 request before closing the connection. Once a request has been
1463 received, the timeout value specified by the
1464 <directive module="core">Timeout</directive> directive applies.</p>
1466 <p>Setting <directive>KeepAliveTimeout</directive> to a high value
1467 may cause performance problems in heavily loaded servers. The
1468 higher the timeout, the more server processes will be kept
1469 occupied waiting on connections with idle clients.</p>
1471 </directivesynopsis>
1473 <directivesynopsis type="section">
1475 <description>Restrict enclosed access controls to only certain HTTP
1476 methods</description>
1477 <syntax><Limit <var>method</var> [<var>method</var>] ... > ...
1478 </Limit></syntax>
1479 <contextlist><context>server config</context><context>virtual host</context>
1480 <context>directory</context><context>.htaccess</context>
1482 <override>All</override>
1485 <p>Access controls are normally effective for
1486 <strong>all</strong> access methods, and this is the usual
1487 desired behavior. <strong>In the general case, access control
1488 directives should not be placed within a
1489 <directive type="section">Limit</directive> section.</strong></p>
1491 <p>The purpose of the <directive type="section">Limit</directive>
1492 directive is to restrict the effect of the access controls to the
1493 nominated HTTP methods. For all other methods, the access
1494 restrictions that are enclosed in the <directive
1495 type="section">Limit</directive> bracket <strong>will have no
1496 effect</strong>. The following example applies the access control
1497 only to the methods <code>POST</code>, <code>PUT</code>, and
1498 <code>DELETE</code>, leaving all other methods unprotected:</p>
1501 <Limit POST PUT DELETE><br />
1503 Require valid-user<br />
1508 <p>The method names listed can be one or more of: <code>GET</code>,
1509 <code>POST</code>, <code>PUT</code>, <code>DELETE</code>,
1510 <code>CONNECT</code>, <code>OPTIONS</code>,
1511 <code>PATCH</code>, <code>PROPFIND</code>, <code>PROPPATCH</code>,
1512 <code>MKCOL</code>, <code>COPY</code>, <code>MOVE</code>,
1513 <code>LOCK</code>, and <code>UNLOCK</code>. <strong>The method name is
1514 case-sensitive.</strong> If <code>GET</code> is used it will also
1515 restrict <code>HEAD</code> requests. The <code>TRACE</code> method
1516 cannot be limited.</p>
1518 <note type="warning">A <directive type="section"
1519 module="core">LimitExcept</directive> section should always be
1520 used in preference to a <directive type="section"
1521 module="core">Limit</directive> section when restricting access,
1522 since a <directive type="section"
1523 module="core">LimitExcept</directive> section provides protection
1524 against arbitrary methods.</note>
1527 </directivesynopsis>
1529 <directivesynopsis type="section">
1530 <name>LimitExcept</name>
1531 <description>Restrict access controls to all HTTP methods
1532 except the named ones</description>
1533 <syntax><LimitExcept <var>method</var> [<var>method</var>] ... > ...
1534 </LimitExcept></syntax>
1535 <contextlist><context>server config</context><context>virtual host</context>
1536 <context>directory</context><context>.htaccess</context>
1538 <override>All</override>
1541 <p><directive type="section">LimitExcept</directive> and
1542 <code></LimitExcept></code> are used to enclose
1543 a group of access control directives which will then apply to any
1544 HTTP access method <strong>not</strong> listed in the arguments;
1545 i.e., it is the opposite of a <directive type="section"
1546 module="core">Limit</directive> section and can be used to control
1547 both standard and nonstandard/unrecognized methods. See the
1548 documentation for <directive module="core"
1549 type="section">Limit</directive> for more details.</p>
1554 <LimitExcept POST GET><br />
1556 Require valid-user<br />
1558 </LimitExcept>
1562 </directivesynopsis>
1565 <name>LimitInternalRecursion</name>
1566 <description>Determine maximum number of internal redirects and nested
1567 subrequests</description>
1568 <syntax>LimitInternalRecursion <var>number</var> [<var>number</var>]</syntax>
1569 <default>LimitInternalRecursion 10</default>
1570 <contextlist><context>server config</context><context>virtual host</context>
1572 <compatibility>Available in Apache 2.0.47 and later</compatibility>
1575 <p>An internal redirect happens, for example, when using the <directive
1576 module="mod_actions">Action</directive> directive, which internally
1577 redirects the original request to a CGI script. A subrequest is Apache's
1578 mechanism to find out what would happen for some URI if it were requested.
1579 For example, <module>mod_dir</module> uses subrequests to look for the
1580 files listed in the <directive module="mod_dir">DirectoryIndex</directive>
1583 <p><directive>LimitInternalRecursion</directive> prevents the server
1584 from crashing when entering an infinite loop of internal redirects or
1585 subrequests. Such loops are usually caused by misconfigurations.</p>
1587 <p>The directive stores two different limits, which are evaluated on
1588 per-request basis. The first <var>number</var> is the maximum number of
1589 internal redirects, that may follow each other. The second <var>number</var>
1590 determines, how deep subrequests may be nested. If you specify only one
1591 <var>number</var>, it will be assigned to both limits.</p>
1593 <example><title>Example</title>
1594 LimitInternalRecursion 5
1597 </directivesynopsis>
1600 <name>LimitRequestBody</name>
1601 <description>Restricts the total size of the HTTP request body sent
1602 from the client</description>
1603 <syntax>LimitRequestBody <var>bytes</var></syntax>
1604 <default>LimitRequestBody 0</default>
1605 <contextlist><context>server config</context><context>virtual host</context>
1606 <context>directory</context><context>.htaccess</context>
1608 <override>All</override>
1611 <p>This directive specifies the number of <var>bytes</var> from 0
1612 (meaning unlimited) to 2147483647 (2GB) that are allowed in a
1615 <p>The <directive>LimitRequestBody</directive> directive allows
1616 the user to set a limit on the allowed size of an HTTP request
1617 message body within the context in which the directive is given
1618 (server, per-directory, per-file or per-location). If the client
1619 request exceeds that limit, the server will return an error
1620 response instead of servicing the request. The size of a normal
1621 request message body will vary greatly depending on the nature of
1622 the resource and the methods allowed on that resource. CGI scripts
1623 typically use the message body for retrieving form information.
1624 Implementations of the <code>PUT</code> method will require
1625 a value at least as large as any representation that the server
1626 wishes to accept for that resource.</p>
1628 <p>This directive gives the server administrator greater
1629 control over abnormal client request behavior, which may be
1630 useful for avoiding some forms of denial-of-service
1633 <p>If, for example, you are permitting file upload to a particular
1634 location, and wish to limit the size of the uploaded file to 100K,
1635 you might use the following directive:</p>
1638 LimitRequestBody 102400
1642 </directivesynopsis>
1645 <name>LimitRequestFields</name>
1646 <description>Limits the number of HTTP request header fields that
1647 will be accepted from the client</description>
1648 <syntax>LimitRequestFields <var>number</var></syntax>
1649 <default>LimitRequestFields 100</default>
1650 <contextlist><context>server config</context></contextlist>
1653 <p><var>Number</var> is an integer from 0 (meaning unlimited) to
1654 32767. The default value is defined by the compile-time
1655 constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
1658 <p>The <directive>LimitRequestFields</directive> directive allows
1659 the server administrator to modify the limit on the number of
1660 request header fields allowed in an HTTP request. A server needs
1661 this value to be larger than the number of fields that a normal
1662 client request might include. The number of request header fields
1663 used by a client rarely exceeds 20, but this may vary among
1664 different client implementations, often depending upon the extent
1665 to which a user has configured their browser to support detailed
1666 content negotiation. Optional HTTP extensions are often expressed
1667 using request header fields.</p>
1669 <p>This directive gives the server administrator greater
1670 control over abnormal client request behavior, which may be
1671 useful for avoiding some forms of denial-of-service attacks.
1672 The value should be increased if normal clients see an error
1673 response from the server that indicates too many fields were
1674 sent in the request.</p>
1679 LimitRequestFields 50
1683 </directivesynopsis>
1686 <name>LimitRequestFieldSize</name>
1687 <description>Limits the size of the HTTP request header allowed from the
1688 client</description>
1689 <syntax>LimitRequestFieldsize <var>bytes</var></syntax>
1690 <default>LimitRequestFieldsize 8190</default>
1691 <contextlist><context>server config</context></contextlist>
1694 <p>This directive specifies the number of <var>bytes</var>
1695 that will be allowed in an HTTP request header.</p>
1697 <p>The <directive>LimitRequestFieldSize</directive> directive
1698 allows the server administrator to reduce or increase the limit
1699 on the allowed size of an HTTP request header field. A server
1700 needs this value to be large enough to hold any one header field
1701 from a normal client request. The size of a normal request header
1702 field will vary greatly among different client implementations,
1703 often depending upon the extent to which a user has configured
1704 their browser to support detailed content negotiation. SPNEGO
1705 authentication headers can be up to 12392 bytes.</p>
1707 <p>This directive gives the server administrator greater
1708 control over abnormal client request behavior, which may be
1709 useful for avoiding some forms of denial-of-service attacks.</p>
1714 LimitRequestFieldSize 4094
1717 <note>Under normal conditions, the value should not be changed from
1721 </directivesynopsis>
1724 <name>LimitRequestLine</name>
1725 <description>Limit the size of the HTTP request line that will be accepted
1726 from the client</description>
1727 <syntax>LimitRequestLine <var>bytes</var></syntax>
1728 <default>LimitRequestLine 8190</default>
1729 <contextlist><context>server config</context></contextlist>
1732 <p>This directive sets the number of <var>bytes</var> that will be
1733 allowed on the HTTP request-line.</p>
1735 <p>The <directive>LimitRequestLine</directive> directive allows
1736 the server administrator to reduce or increase the limit on the allowed size
1737 of a client's HTTP request-line. Since the request-line consists of the
1738 HTTP method, URI, and protocol version, the
1739 <directive>LimitRequestLine</directive> directive places a
1740 restriction on the length of a request-URI allowed for a request
1741 on the server. A server needs this value to be large enough to
1742 hold any of its resource names, including any information that
1743 might be passed in the query part of a <code>GET</code> request.</p>
1745 <p>This directive gives the server administrator greater
1746 control over abnormal client request behavior, which may be
1747 useful for avoiding some forms of denial-of-service attacks.</p>
1752 LimitRequestLine 4094
1755 <note>Under normal conditions, the value should not be changed from
1758 </directivesynopsis>
1761 <name>LimitXMLRequestBody</name>
1762 <description>Limits the size of an XML-based request body</description>
1763 <syntax>LimitXMLRequestBody <var>bytes</var></syntax>
1764 <default>LimitXMLRequestBody 1000000</default>
1765 <contextlist><context>server config</context><context>virtual host</context>
1766 <context>directory</context><context>.htaccess</context></contextlist>
1767 <override>All</override>
1770 <p>Limit (in bytes) on maximum size of an XML-based request
1771 body. A value of <code>0</code> will disable any checking.</p>
1776 LimitXMLRequestBody 0
1780 </directivesynopsis>
1782 <directivesynopsis type="section">
1783 <name>Location</name>
1784 <description>Applies the enclosed directives only to matching
1786 <syntax><Location
1787 <var>URL-path</var>|<var>URL</var>> ... </Location></syntax>
1788 <contextlist><context>server config</context><context>virtual host</context>
1792 <p>The <directive type="section">Location</directive> directive
1793 limits the scope of the enclosed directives by URL. It is similar to the
1794 <directive type="section" module="core">Directory</directive>
1795 directive, and starts a subsection which is terminated with a
1796 <code></Location></code> directive. <directive
1797 type="section">Location</directive> sections are processed in the
1798 order they appear in the configuration file, after the <directive
1799 type="section" module="core">Directory</directive> sections and
1800 <code>.htaccess</code> files are read, and after the <directive
1801 type="section" module="core">Files</directive> sections.</p>
1803 <p><directive type="section">Location</directive> sections operate
1804 completely outside the filesystem. This has several consequences.
1805 Most importantly, <directive type="section">Location</directive>
1806 directives should not be used to control access to filesystem
1807 locations. Since several different URLs may map to the same
1808 filesystem location, such access controls may by circumvented.</p>
1810 <note><title>When to use <directive
1811 type="section">Location</directive></title>
1813 <p>Use <directive type="section">Location</directive> to apply
1814 directives to content that lives outside the filesystem. For
1815 content that lives in the filesystem, use <directive
1816 type="section" module="core">Directory</directive> and <directive
1817 type="section" module="core">Files</directive>. An exception is
1818 <code><Location /></code>, which is an easy way to
1819 apply a configuration to the entire server.</p>
1822 <p>For all origin (non-proxy) requests, the URL to be matched is a
1823 URL-path of the form <code>/path/</code>. No scheme, hostname,
1824 port, or query string may be included. For proxy requests, the
1825 URL to be matched is of the form
1826 <code>scheme://servername/path</code>, and you must include the
1829 <p>The URL may use wildcards. In a wild-card string, <code>?</code> matches
1830 any single character, and <code>*</code> matches any sequences of
1834 expressions can also be used, with the addition of the
1835 <code>~</code> character. For example:</p>
1838 <Location ~ "/(extra|special)/data">
1841 <p>would match URLs that contained the substring <code>/extra/data</code>
1842 or <code>/special/data</code>. The directive <directive
1843 type="section" module="core">LocationMatch</directive> behaves
1844 identical to the regex version of <directive
1845 type="section">Location</directive>.</p>
1847 <p>The <directive type="section">Location</directive>
1848 functionality is especially useful when combined with the
1849 <directive module="core">SetHandler</directive>
1850 directive. For example, to enable status requests, but allow them
1851 only from browsers at <code>foo.com</code>, you might use:</p>
1854 <Location /status><br />
1856 SetHandler server-status<br />
1857 Order Deny,Allow<br />
1859 Allow from .foo.com<br />
1864 <note><title>Note about / (slash)</title>
1865 <p>The slash character has special meaning depending on where in a
1866 URL it appears. People may be used to its behavior in the filesystem
1867 where multiple adjacent slashes are frequently collapsed to a single
1868 slash (<em>i.e.</em>, <code>/home///foo</code> is the same as
1869 <code>/home/foo</code>). In URL-space this is not necessarily true.
1870 The <directive type="section" module="core">LocationMatch</directive>
1871 directive and the regex version of <directive type="section"
1872 >Location</directive> require you to explicitly specify multiple
1873 slashes if that is your intention.</p>
1875 <p>For example, <code><LocationMatch ^/abc></code> would match
1876 the request URL <code>/abc</code> but not the request URL <code>
1877 //abc</code>. The (non-regex) <directive type="section"
1878 >Location</directive> directive behaves similarly when used for
1879 proxy requests. But when (non-regex) <directive type="section"
1880 >Location</directive> is used for non-proxy requests it will
1881 implicitly match multiple slashes with a single slash. For example,
1882 if you specify <code><Location /abc/def></code> and the
1883 request is to <code>/abc//def</code> then it will match.</p>
1886 <seealso><a href="../sections.html">How <Directory>, <Location>
1887 and <Files> sections work</a> for an explanation of how these
1888 different sections are combined when a request is received</seealso>
1889 </directivesynopsis>
1891 <directivesynopsis type="section">
1892 <name>LocationMatch</name>
1893 <description>Applies the enclosed directives only to regular-expression
1894 matching URLs</description>
1895 <syntax><LocationMatch
1896 <var>regex</var>> ... </LocationMatch></syntax>
1897 <contextlist><context>server config</context><context>virtual host</context>
1901 <p>The <directive type="section">LocationMatch</directive> directive
1902 limits the scope of the enclosed directives by URL, in an identical manner
1903 to <directive module="core" type="section">Location</directive>. However,
1904 it takes a regular expression as an argument instead of a simple
1905 string. For example:</p>
1908 <LocationMatch "/(extra|special)/data">
1911 <p>would match URLs that contained the substring <code>/extra/data</code>
1912 or <code>/special/data</code>.</p>
1915 <seealso><a href="../sections.html">How <Directory>, <Location>
1916 and <Files> sections work</a> for an explanation of how these
1917 different sections are combined when a request is received</seealso>
1918 </directivesynopsis>
1921 <name>LogLevel</name>
1922 <description>Controls the verbosity of the ErrorLog</description>
1923 <syntax>LogLevel <var>level</var></syntax>
1924 <default>LogLevel warn</default>
1925 <contextlist><context>server config</context><context>virtual host</context>
1929 <p><directive>LogLevel</directive> adjusts the verbosity of the
1930 messages recorded in the error logs (see <directive
1931 module="core">ErrorLog</directive> directive). The following
1932 <var>level</var>s are available, in order of decreasing
1936 <columnspec><column width=".2"/><column width=".3"/><column width=".5"/>
1939 <th><strong>Level</strong> </th>
1941 <th><strong>Description</strong> </th>
1943 <th><strong>Example</strong> </th>
1947 <td><code>emerg</code> </td>
1949 <td>Emergencies - system is unusable.</td>
1951 <td>"Child cannot open lock file. Exiting"</td>
1955 <td><code>alert</code> </td>
1957 <td>Action must be taken immediately.</td>
1959 <td>"getpwuid: couldn't determine user name from uid"</td>
1963 <td><code>crit</code> </td>
1965 <td>Critical Conditions.</td>
1967 <td>"socket: Failed to get a socket, exiting child"</td>
1971 <td><code>error</code> </td>
1973 <td>Error conditions.</td>
1975 <td>"Premature end of script headers"</td>
1979 <td><code>warn</code> </td>
1981 <td>Warning conditions.</td>
1983 <td>"child process 1234 did not exit, sending another
1988 <td><code>notice</code> </td>
1990 <td>Normal but significant condition.</td>
1992 <td>"httpd: caught SIGBUS, attempting to dump core in
1997 <td><code>info</code> </td>
1999 <td>Informational.</td>
2001 <td>"Server seems busy, (you may need to increase
2002 StartServers, or Min/MaxSpareServers)..."</td>
2006 <td><code>debug</code> </td>
2008 <td>Debug-level messages</td>
2010 <td>"Opening config file ..."</td>
2014 <p>When a particular level is specified, messages from all
2015 other levels of higher significance will be reported as well.
2016 <em>E.g.</em>, when <code>LogLevel info</code> is specified,
2017 then messages with log levels of <code>notice</code> and
2018 <code>warn</code> will also be posted.</p>
2020 <p>Using a level of at least <code>crit</code> is
2029 <note><title>Note</title>
2030 <p>When logging to a regular file messages of the level
2031 <code>notice</code> cannot be suppressed and thus are always
2032 logged. However, this doesn't apply when logging is done
2033 using <code>syslog</code>.</p>
2036 </directivesynopsis>
2039 <name>MaxKeepAliveRequests</name>
2040 <description>Number of requests allowed on a persistent
2041 connection</description>
2042 <syntax>MaxKeepAliveRequests <var>number</var></syntax>
2043 <default>MaxKeepAliveRequests 100</default>
2044 <contextlist><context>server config</context><context>virtual host</context>
2048 <p>The <directive>MaxKeepAliveRequests</directive> directive
2049 limits the number of requests allowed per connection when
2050 <directive module="core" >KeepAlive</directive> is on. If it is
2051 set to <code>0</code>, unlimited requests will be allowed. We
2052 recommend that this setting be kept to a high value for maximum
2053 server performance.</p>
2058 MaxKeepAliveRequests 500
2061 </directivesynopsis>
2064 <name>NameVirtualHost</name>
2065 <description>Designates an IP address for name-virtual
2066 hosting</description>
2067 <syntax>NameVirtualHost <var>addr</var>[:<var>port</var>]</syntax>
2068 <contextlist><context>server config</context></contextlist>
2071 <p>The <directive>NameVirtualHost</directive> directive is a
2072 required directive if you want to configure <a
2073 href="../vhosts/">name-based virtual hosts</a>.</p>
2075 <p>Although <var>addr</var> can be hostname it is recommended
2076 that you always use an IP address, e.g.</p>
2079 NameVirtualHost 111.22.33.44
2082 <p>With the <directive>NameVirtualHost</directive> directive you
2083 specify the IP address on which the server will receive requests
2084 for the name-based virtual hosts. This will usually be the address
2085 to which your name-based virtual host names resolve. In cases
2086 where a firewall or other proxy receives the requests and forwards
2087 them on a different IP address to the server, you must specify the
2088 IP address of the physical interface on the machine which will be
2089 servicing the requests. If you have multiple name-based hosts on
2090 multiple addresses, repeat the directive for each address.</p>
2092 <note><title>Note</title>
2093 <p>Note, that the "main server" and any <code>_default_</code> servers
2094 will <strong>never</strong> be served for a request to a
2095 <directive>NameVirtualHost</directive> IP address (unless for some
2096 reason you specify <directive>NameVirtualHost</directive> but then
2097 don't define any <directive>VirtualHost</directive>s for that
2101 <p>Optionally you can specify a port number on which the
2102 name-based virtual hosts should be used, e.g.</p>
2105 NameVirtualHost 111.22.33.44:8080
2108 <p>IPv6 addresses must be enclosed in square brackets, as shown
2109 in the following example:</p>
2112 NameVirtualHost [fe80::a00:20ff:fea7:ccea]:8080
2115 <p>To receive requests on all interfaces, you can use an argument of
2122 <note><title>Argument to <directive type="section">VirtualHost</directive>
2124 <p>Note that the argument to the <directive
2125 type="section">VirtualHost</directive> directive must
2126 exactly match the argument to the <directive
2127 >NameVirtualHost</directive> directive.</p>
2130 NameVirtualHost 1.2.3.4<br />
2131 <VirtualHost 1.2.3.4><br />
2133 </VirtualHost><br />
2138 <seealso><a href="../vhosts/">Virtual Hosts
2139 documentation</a></seealso>
2141 </directivesynopsis>
2144 <name>Options</name>
2145 <description>Configures what features are available in a particular
2146 directory</description>
2148 [+|-]<var>option</var> [[+|-]<var>option</var>] ...</syntax>
2149 <default>Options All</default>
2150 <contextlist><context>server config</context><context>virtual host</context>
2151 <context>directory</context><context>.htaccess</context>
2153 <override>Options</override>
2156 <p>The <directive>Options</directive> directive controls which
2157 server features are available in a particular directory.</p>
2159 <p><var>option</var> can be set to <code>None</code>, in which
2160 case none of the extra features are enabled, or one or more of
2164 <dt><code>All</code></dt>
2166 <dd>All options except for <code>MultiViews</code>. This is the default
2169 <dt><code>ExecCGI</code></dt>
2172 Execution of CGI scripts using <module>mod_cgi</module>
2175 <dt><code>FollowSymLinks</code></dt>
2179 The server will follow symbolic links in this directory.
2181 <p>Even though the server follows the symlink it does <em>not</em>
2182 change the pathname used to match against <directive type="section"
2183 module="core">Directory</directive> sections.</p>
2184 <p>Note also, that this option <strong>gets ignored</strong> if set
2185 inside a <directive type="section" module="core">Location</directive>
2189 <dt><code>Includes</code></dt>
2192 Server-side includes provided by <module>mod_include</module>
2195 <dt><code>IncludesNOEXEC</code></dt>
2199 Server-side includes are permitted, but the <code>#exec
2200 cmd</code> and <code>#exec cgi</code> are disabled. It is still
2201 possible to <code>#include virtual</code> CGI scripts from
2202 <directive module="mod_alias">ScriptAlias</directive>ed
2205 <dt><code>Indexes</code></dt>
2208 If a URL which maps to a directory is requested, and there
2209 is no <directive module="mod_dir">DirectoryIndex</directive>
2210 (<em>e.g.</em>, <code>index.html</code>) in that directory, then
2211 <module>mod_autoindex</module> will return a formatted listing
2212 of the directory.</dd>
2214 <dt><code>MultiViews</code></dt>
2217 <a href="../content-negotiation.html">Content negotiated</a>
2218 "MultiViews" are allowed using
2219 <module>mod_negotiation</module>.</dd>
2221 <dt><code>SymLinksIfOwnerMatch</code></dt>
2223 <dd>The server will only follow symbolic links for which the
2224 target file or directory is owned by the same user id as the
2227 <note><title>Note</title> This option gets ignored if
2228 set inside a <directive module="core"
2229 type="section">Location</directive> section.</note>
2233 <p>Normally, if multiple <directive>Options</directive> could
2234 apply to a directory, then the most specific one is used and
2235 others are ignored; the options are not merged. (See <a
2236 href="../sections.html#mergin">how sections are merged</a>.)
2237 However if <em>all</em> the options on the
2238 <directive>Options</directive> directive are preceded by a
2239 <code>+</code> or <code>-</code> symbol, the options are
2240 merged. Any options preceded by a <code>+</code> are added to the
2241 options currently in force, and any options preceded by a
2242 <code>-</code> are removed from the options currently in
2245 <p>For example, without any <code>+</code> and <code>-</code> symbols:</p>
2248 <Directory /web/docs><br />
2250 Options Indexes FollowSymLinks<br />
2252 </Directory><br />
2254 <Directory /web/docs/spec><br />
2256 Options Includes<br />
2261 <p>then only <code>Includes</code> will be set for the
2262 <code>/web/docs/spec</code> directory. However if the second
2263 <directive>Options</directive> directive uses the <code>+</code> and
2264 <code>-</code> symbols:</p>
2267 <Directory /web/docs><br />
2269 Options Indexes FollowSymLinks<br />
2271 </Directory><br />
2273 <Directory /web/docs/spec><br />
2275 Options +Includes -Indexes<br />
2280 <p>then the options <code>FollowSymLinks</code> and
2281 <code>Includes</code> are set for the <code>/web/docs/spec</code>
2284 <note><title>Note</title>
2285 <p>Using <code>-IncludesNOEXEC</code> or
2286 <code>-Includes</code> disables server-side includes completely
2287 regardless of the previous setting.</p>
2290 <p>The default in the absence of any other settings is
2291 <code>All</code>.</p>
2293 </directivesynopsis>
2296 <name>Require</name>
2297 <description>Selects which authenticated users can access
2298 a resource</description>
2299 <syntax>Require <var>entity-name</var> [<var>entity-name</var>] ...</syntax>
2300 <contextlist><context>directory</context><context>.htaccess</context>
2302 <override>AuthConfig</override>
2305 <p>This directive selects which authenticated users can access
2306 a resource. The allowed syntaxes are:</p>
2309 <dt><code>Require user <var>userid</var> [<var>userid</var>]
2311 <dd>Only the named users can access the resource.</dd>
2313 <dt><code>Require group <var>group-name</var> [<var>group-name</var>]
2315 <dd>Only users in the named groups can access the resource.</dd>
2317 <dt><code>Require valid-user</code></dt>
2318 <dd>All valid users can access the resource.</dd>
2321 <p><directive>Require</directive> must be accompanied by
2322 <directive module="core">AuthName</directive> and <directive
2323 module="core">AuthType</directive> directives, and directives such
2324 as <directive module="mod_authn_file">AuthUserFile</directive>
2325 and <directive module="mod_authz_groupfile">AuthGroupFile</directive> (to
2326 define users and groups) in order to work correctly. Example:</p>
2329 AuthType Basic<br />
2330 AuthName "Restricted Resource"<br />
2331 AuthUserFile /web/users<br />
2332 AuthGroupFile /web/groups<br />
2336 <p>Access controls which are applied in this way are effective for
2337 <strong>all</strong> methods. <strong>This is what is normally
2338 desired.</strong> If you wish to apply access controls only to
2339 specific methods, while leaving other methods unprotected, then
2340 place the <directive>Require</directive> statement into a
2341 <directive module="core" type="section">Limit</directive>
2344 <seealso><directive module="core">Satisfy</directive></seealso>
2345 <seealso><module>mod_authz_host</module></seealso>
2346 </directivesynopsis>
2349 <name>RLimitCPU</name>
2350 <description>Limits the CPU consumption of processes launched
2351 by Apache children</description>
2352 <syntax>RLimitCPU <var>seconds</var>|max [<var>seconds</var>|max]</syntax>
2353 <default>Unset; uses operating system defaults</default>
2354 <contextlist><context>server config</context><context>virtual host</context>
2355 <context>directory</context><context>.htaccess</context></contextlist>
2356 <override>All</override>
2359 <p>Takes 1 or 2 parameters. The first parameter sets the soft
2360 resource limit for all processes and the second parameter sets
2361 the maximum resource limit. Either parameter can be a number,
2362 or <code>max</code> to indicate to the server that the limit should
2363 be set to the maximum allowed by the operating system
2364 configuration. Raising the maximum resource limit requires that
2365 the server is running as <code>root</code>, or in the initial startup
2368 <p>This applies to processes forked off from Apache children
2369 servicing requests, not the Apache children themselves. This
2370 includes CGI scripts and SSI exec commands, but not any
2371 processes forked off from the Apache parent such as piped
2374 <p>CPU resource limits are expressed in seconds per
2377 <seealso><directive module="core">RLimitMEM</directive></seealso>
2378 <seealso><directive module="core">RLimitNPROC</directive></seealso>
2379 </directivesynopsis>
2382 <name>RLimitMEM</name>
2383 <description>Limits the memory consumption of processes launched
2384 by Apache children</description>
2385 <syntax>RLimitMEM <var>bytes</var>|max [<var>bytes</var>|max]</syntax>
2386 <default>Unset; uses operating system defaults</default>
2387 <contextlist><context>server config</context><context>virtual host</context>
2388 <context>directory</context><context>.htaccess</context></contextlist>
2389 <override>All</override>
2392 <p>Takes 1 or 2 parameters. The first parameter sets the soft
2393 resource limit for all processes and the second parameter sets
2394 the maximum resource limit. Either parameter can be a number,
2395 or <code>max</code> to indicate to the server that the limit should
2396 be set to the maximum allowed by the operating system
2397 configuration. Raising the maximum resource limit requires that
2398 the server is running as <code>root</code>, or in the initial startup
2401 <p>This applies to processes forked off from Apache children
2402 servicing requests, not the Apache children themselves. This
2403 includes CGI scripts and SSI exec commands, but not any
2404 processes forked off from the Apache parent such as piped
2407 <p>Memory resource limits are expressed in bytes per
2410 <seealso><directive module="core">RLimitCPU</directive></seealso>
2411 <seealso><directive module="core">RLimitNPROC</directive></seealso>
2412 </directivesynopsis>
2415 <name>RLimitNPROC</name>
2416 <description>Limits the number of processes that can be launched by
2417 processes launched by Apache children</description>
2418 <syntax>RLimitNPROC <var>number</var>|max [<var>number</var>|max]</syntax>
2419 <default>Unset; uses operating system defaults</default>
2420 <contextlist><context>server config</context><context>virtual host</context>
2421 <context>directory</context><context>.htaccess</context></contextlist>
2422 <override>All</override>
2425 <p>Takes 1 or 2 parameters. The first parameter sets the soft
2426 resource limit for all processes and the second parameter sets
2427 the maximum resource limit. Either parameter can be a number,
2428 or <code>max</code> to indicate to the server that the limit
2429 should be set to the maximum allowed by the operating system
2430 configuration. Raising the maximum resource limit requires that
2431 the server is running as <code>root</code>, or in the initial startup
2434 <p>This applies to processes forked off from Apache children
2435 servicing requests, not the Apache children themselves. This
2436 includes CGI scripts and SSI exec commands, but not any
2437 processes forked off from the Apache parent such as piped
2440 <p>Process limits control the number of processes per user.</p>
2442 <note><title>Note</title>
2443 <p>If CGI processes are <strong>not</strong> running
2444 under user ids other than the web server user id, this directive
2445 will limit the number of processes that the server itself can
2446 create. Evidence of this situation will be indicated by
2447 <strong><code>cannot fork</code></strong> messages in the
2448 <code>error_log</code>.</p>
2451 <seealso><directive module="core">RLimitMEM</directive></seealso>
2452 <seealso><directive module="core">RLimitCPU</directive></seealso>
2453 </directivesynopsis>
2456 <name>Satisfy</name>
2457 <description>Interaction between host-level access control and
2458 user authentication</description>
2459 <syntax>Satisfy Any|All</syntax>
2460 <default>Satisfy All</default>
2461 <contextlist><context>directory</context><context>.htaccess</context>
2463 <override>AuthConfig</override>
2464 <compatibility>Influenced by <directive module="core" type="section"
2465 >Limit</directive> and <directive module="core"
2466 type="section">LimitExcept</directive> in version 2.0.51 and
2467 later</compatibility>
2470 <p>Access policy if both <directive
2471 module="mod_authz_host">Allow</directive> and <directive
2472 module="core">Require</directive> used. The parameter can be
2473 either <code>All</code> or <code>Any</code>. This directive is only
2474 useful if access to a particular area is being restricted by both
2475 username/password <em>and</em> client host address. In this case
2476 the default behavior (<code>All</code>) is to require that the client
2477 passes the address access restriction <em>and</em> enters a valid
2478 username and password. With the <code>Any</code> option the client will be
2479 granted access if they either pass the host restriction or enter a
2480 valid username and password. This can be used to password restrict
2481 an area, but to let clients from particular addresses in without
2482 prompting for a password.</p>
2484 <p>For example, if you wanted to let people on your network have
2485 unrestricted access to a portion of your website, but require that
2486 people outside of your network provide a password, you could use a
2487 configuration similar to the following:</p>
2490 Require valid-user<br />
2491 Allow from 192.168.1<br />
2495 <p>Since version 2.0.51 <directive>Satisfy</directive> directives can
2496 be restricted to particular methods by <directive module="core"
2497 type="section">Limit</directive> and <directive module="core" type="section"
2498 >LimitExcept</directive> sections.</p>
2500 <seealso><directive module="mod_authz_host">Allow</directive></seealso>
2501 <seealso><directive module="core">Require</directive></seealso>
2502 </directivesynopsis>
2505 <name>ScriptInterpreterSource</name>
2506 <description>Technique for locating the interpreter for CGI
2507 scripts</description>
2508 <syntax>ScriptInterpreterSource Registry|Registry-Strict|Script</syntax>
2509 <default>ScriptInterpreterSource Script</default>
2510 <contextlist><context>server config</context><context>virtual host</context>
2511 <context>directory</context><context>.htaccess</context></contextlist>
2512 <override>FileInfo</override>
2513 <compatibility>Win32 only;
2514 option <code>Registry-Strict</code> is available in Apache 2.0 and
2515 later</compatibility>
2518 <p>This directive is used to control how Apache finds the
2519 interpreter used to run CGI scripts. The default setting is
2520 <code>Script</code>. This causes Apache to use the interpreter pointed to
2521 by the shebang line (first line, starting with <code>#!</code>) in the
2522 script. On Win32 systems this line usually looks like:</p>
2525 #!C:/Perl/bin/perl.exe
2528 <p>or, if <code>perl</code> is in the <code>PATH</code>, simply:</p>
2534 <p>Setting <code>ScriptInterpreterSource Registry</code> will
2535 cause the Windows Registry tree <code>HKEY_CLASSES_ROOT</code> to be
2536 searched using the script file extension (e.g., <code>.pl</code>) as a
2537 search key. The command defined by the registry subkey
2538 <code>Shell\ExecCGI\Command</code> or, if it does not exist, by the subkey
2539 <code>Shell\Open\Command</code> is used to open the script file. If the
2540 registry keys cannot be found, Apache falls back to the behavior of the
2541 <code>Script</code> option.</p>
2543 <note type="warning"><title>Security</title>
2544 <p>Be careful when using <code>ScriptInterpreterSource
2545 Registry</code> with <directive
2546 module="mod_alias">ScriptAlias</directive>'ed directories, because
2547 Apache will try to execute <strong>every</strong> file within this
2548 directory. The <code>Registry</code> setting may cause undesired
2549 program calls on files which are typically not executed. For
2550 example, the default open command on <code>.htm</code> files on
2551 most Windows systems will execute Microsoft Internet Explorer, so
2552 any HTTP request for an <code>.htm</code> file existing within the
2553 script directory would start the browser in the background on the
2554 server. This is a good way to crash your system within a minute or
2558 <p>The option <code>Registry-Strict</code> which is new in Apache
2559 2.0 does the same thing as <code>Registry</code> but uses only the
2560 subkey <code>Shell\ExecCGI\Command</code>. The
2561 <code>ExecCGI</code> key is not a common one. It must be
2562 configured manually in the windows registry and hence prevents
2563 accidental program calls on your system.</p>
2565 </directivesynopsis>
2568 <name>ServerAdmin</name>
2569 <description>Email address that the server includes in error
2570 messages sent to the client</description>
2571 <syntax>ServerAdmin <var>email-address</var>|<var>URL</var></syntax>
2572 <contextlist><context>server config</context><context>virtual host</context>
2576 <p>The <directive>ServerAdmin</directive> sets the contact address
2577 that the server includes in any error messages it returns to the
2578 client. If the <code>httpd</code> doesn't recognize the supplied argument
2580 assumes, that it's an <var>email-address</var> and prepends it with
2581 <code>mailto:</code> in hyperlink targets. However, it's recommended to
2582 actually use an email address, since there are a lot of CGI scripts that
2583 make that assumption. If you want to use an URL, it should point to another
2584 server under your control. Otherwise users may not be able to contact you in
2587 <p>It may be worth setting up a dedicated address for this, e.g.</p>
2590 ServerAdmin www-admin@foo.example.com
2592 <p>as users do not always mention that they are talking about the
2595 </directivesynopsis>
2598 <name>ServerAlias</name>
2599 <description>Alternate names for a host used when matching requests
2600 to name-virtual hosts</description>
2601 <syntax>ServerAlias <var>hostname</var> [<var>hostname</var>] ...</syntax>
2602 <contextlist><context>virtual host</context></contextlist>
2605 <p>The <directive>ServerAlias</directive> directive sets the
2606 alternate names for a host, for use with <a
2607 href="../vhosts/name-based.html">name-based virtual hosts</a>.</p>
2610 <VirtualHost *><br />
2611 ServerName server.domain.com<br />
2612 ServerAlias server server2.domain.com server2<br />
2614 </VirtualHost>
2617 <seealso><a href="../vhosts/">Apache Virtual Host documentation</a></seealso>
2618 </directivesynopsis>
2621 <name>ServerName</name>
2622 <description>Hostname and port that the server uses to identify
2623 itself</description>
2624 <syntax>ServerName <var>fully-qualified-domain-name</var>[:<var>port</var>]</syntax>
2625 <contextlist><context>server config</context><context>virtual host</context>
2627 <compatibility>In version 2.0, this
2628 directive supersedes the functionality of the <directive>Port</directive>
2629 directive from version 1.3.</compatibility>
2632 <p>The <directive>ServerName</directive> directive sets the hostname and
2633 port that the server uses to identify itself. This is used when
2634 creating redirection URLs. For example, if the name of the
2635 machine hosting the web server is <code>simple.example.com</code>,
2636 but the machine also has the DNS alias <code>www.example.com</code>
2637 and you wish the web server to be so identified, the following
2638 directive should be used:</p>
2641 ServerName www.example.com:80
2644 <p>If no <directive>ServerName</directive> is specified, then the
2645 server attempts to deduce the hostname by performing a reverse
2646 lookup on the IP address. If no port is specified in the
2647 <directive>ServerName</directive>, then the server will use the port
2649 request. For optimal reliability and predictability, you should
2650 specify an explicit hostname and port using the
2651 <directive>ServerName</directive> directive.</p>
2653 <p>If you are using <a
2654 href="../vhosts/name-based.html">name-based virtual hosts</a>,
2655 the <directive>ServerName</directive> inside a
2656 <directive type="section" module="core">VirtualHost</directive>
2657 section specifies what hostname must appear in the request's
2658 <code>Host:</code> header to match this virtual host.</p>
2660 <p>See the description of the
2661 <directive module="core">UseCanonicalName</directive> directive for
2662 settings which determine whether self-referential URL's (e.g., by the
2663 <module>mod_dir</module> module) will refer to the
2664 specified port, or to the port number given in the client's request.
2668 <seealso><a href="../dns-caveats.html">Issues Regarding DNS and
2669 Apache</a></seealso>
2670 <seealso><a href="../vhosts/">Apache virtual host
2671 documentation</a></seealso>
2672 <seealso><directive module="core">UseCanonicalName</directive></seealso>
2673 <seealso><directive module="core">NameVirtualHost</directive></seealso>
2674 <seealso><directive module="core">ServerAlias</directive></seealso>
2675 </directivesynopsis>
2678 <name>ServerPath</name>
2679 <description>Legacy URL pathname for a name-based virtual host that
2680 is accessed by an incompatible browser</description>
2681 <syntax>ServerPath <var>URL-path</var></syntax>
2682 <contextlist><context>virtual host</context></contextlist>
2685 <p>The <directive>ServerPath</directive> directive sets the legacy
2686 URL pathname for a host, for use with <a
2687 href="../vhosts/">name-based virtual hosts</a>.</p>
2689 <seealso><a href="../vhosts/">Apache Virtual Host documentation</a></seealso>
2690 </directivesynopsis>
2693 <name>ServerRoot</name>
2694 <description>Base directory for the server installation</description>
2695 <syntax>ServerRoot <var>directory-path</var></syntax>
2696 <default>ServerRoot /usr/local/apache</default>
2697 <contextlist><context>server config</context></contextlist>
2700 <p>The <directive>ServerRoot</directive> directive sets the
2701 directory in which the server lives. Typically it will contain the
2702 subdirectories <code>conf/</code> and <code>logs/</code>. Relative
2703 paths in other configuration directives (such as <directive
2704 module="core">Include</directive> or <directive
2705 module="mod_so">LoadModule</directive>, for example) are taken as
2706 relative to this directory.</p>
2708 <example><title>Example</title>
2709 ServerRoot /home/httpd
2713 <seealso><a href="../invoking.html">the <code>-d</code>
2714 option to <code>httpd</code></a></seealso>
2715 <seealso><a href="../misc/security_tips.html#serverroot">the
2716 security tips</a> for information on how to properly set
2717 permissions on the <directive>ServerRoot</directive></seealso>
2718 </directivesynopsis>
2721 <name>ServerSignature</name>
2722 <description>Configures the footer on server-generated documents</description>
2723 <syntax>ServerSignature On|Off|EMail</syntax>
2724 <default>ServerSignature Off</default>
2725 <contextlist><context>server config</context><context>virtual host</context>
2726 <context>directory</context><context>.htaccess</context>
2728 <override>All</override>
2731 <p>The <directive>ServerSignature</directive> directive allows the
2732 configuration of a trailing footer line under server-generated
2733 documents (error messages, <module>mod_proxy</module> ftp directory
2734 listings, <module>mod_info</module> output, ...). The reason why you
2735 would want to enable such a footer line is that in a chain of proxies,
2736 the user often has no possibility to tell which of the chained servers
2737 actually produced a returned error message.</p>
2739 <p>The <code>Off</code>
2740 setting, which is the default, suppresses the footer line (and is
2741 therefore compatible with the behavior of Apache-1.2 and
2742 below). The <code>On</code> setting simply adds a line with the
2743 server version number and <directive
2744 module="core">ServerName</directive> of the serving virtual host,
2745 and the <code>EMail</code> setting additionally creates a
2746 "mailto:" reference to the <directive
2747 module="core">ServerAdmin</directive> of the referenced
2750 <p>After version 2.0.44, the details of the server version number
2751 presented are controlled by the <directive
2752 module="core">ServerTokens</directive> directive.</p>
2754 <seealso><directive module="core">ServerTokens</directive></seealso>
2755 </directivesynopsis>
2758 <name>ServerTokens</name>
2759 <description>Configures the <code>Server</code> HTTP response
2760 header</description>
2761 <syntax>ServerTokens Major|Minor|Min[imal]|Prod[uctOnly]|OS|Full</syntax>
2762 <default>ServerTokens Full</default>
2763 <contextlist><context>server config</context></contextlist>
2766 <p>This directive controls whether <code>Server</code> response
2767 header field which is sent back to clients includes a
2768 description of the generic OS-type of the server as well as
2769 information about compiled-in modules.</p>
2772 <dt><code>ServerTokens Prod[uctOnly]</code></dt>
2774 <dd>Server sends (<em>e.g.</em>): <code>Server:
2777 <dt><code>ServerTokens Major</code></dt>
2779 <dd>Server sends (<em>e.g.</em>): <code>Server:
2780 Apache/2</code></dd>
2782 <dt><code>ServerTokens Minor</code></dt>
2784 <dd>Server sends (<em>e.g.</em>): <code>Server:
2785 Apache/2.0</code></dd>
2787 <dt><code>ServerTokens Min[imal]</code></dt>
2789 <dd>Server sends (<em>e.g.</em>): <code>Server:
2790 Apache/2.0.41</code></dd>
2792 <dt><code>ServerTokens OS</code></dt>
2794 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.0.41
2797 <dt><code>ServerTokens Full</code> (or not specified)</dt>
2799 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.0.41
2800 (Unix) PHP/4.2.2 MyMod/1.2</code></dd>
2803 <p>This setting applies to the entire server, and cannot be
2804 enabled or disabled on a virtualhost-by-virtualhost basis.</p>
2806 <p>After version 2.0.44, this directive also controls the
2807 information presented by the <directive
2808 module="core">ServerSignature</directive> directive.</p>
2810 <seealso><directive module="core">ServerSignature</directive></seealso>
2811 </directivesynopsis>
2814 <name>SetHandler</name>
2815 <description>Forces all matching files to be processed by a
2816 handler</description>
2817 <syntax>SetHandler <var>handler-name</var>|None</syntax>
2818 <contextlist><context>server config</context><context>virtual host</context>
2819 <context>directory</context><context>.htaccess</context>
2821 <override>FileInfo</override>
2822 <compatibility>Moved into the core in Apache 2.0</compatibility>
2825 <p>When placed into an <code>.htaccess</code> file or a
2826 <directive type="section" module="core">Directory</directive> or
2827 <directive type="section" module="core">Location</directive>
2828 section, this directive forces all matching files to be parsed
2829 through the <a href="../handler.html">handler</a> given by
2830 <var>handler-name</var>. For example, if you had a directory you
2831 wanted to be parsed entirely as imagemap rule files, regardless
2832 of extension, you might put the following into an
2833 <code>.htaccess</code> file in that directory:</p>
2836 SetHandler imap-file
2839 <p>Another example: if you wanted to have the server display a
2840 status report whenever a URL of
2841 <code>http://servername/status</code> was called, you might put
2842 the following into <code>httpd.conf</code>:</p>
2845 <Location /status><br />
2847 SetHandler server-status<br />
2852 <p>You can override an earlier defined <directive>SetHandler</directive>
2853 directive by using the value <code>None</code>.</p>
2856 <seealso><directive module="mod_mime">AddHandler</directive></seealso>
2858 </directivesynopsis>
2861 <name>SetInputFilter</name>
2862 <description>Sets the filters that will process client requests and POST
2864 <syntax>SetInputFilter <var>filter</var>[;<var>filter</var>...]</syntax>
2865 <contextlist><context>server config</context><context>virtual host</context>
2866 <context>directory</context><context>.htaccess</context>
2868 <override>FileInfo</override>
2871 <p>The <directive>SetInputFilter</directive> directive sets the
2872 filter or filters which will process client requests and POST
2873 input when they are received by the server. This is in addition to
2874 any filters defined elsewhere, including the
2875 <directive module="mod_mime">AddInputFilter</directive>
2878 <p>If more than one filter is specified, they must be separated
2879 by semicolons in the order in which they should process the
2882 <seealso><a href="../filter.html">Filters</a> documentation</seealso>
2883 </directivesynopsis>
2886 <name>SetOutputFilter</name>
2887 <description>Sets the filters that will process responses from the
2888 server</description>
2889 <syntax>SetOutputFilter <var>filter</var>[;<var>filter</var>...]</syntax>
2890 <contextlist><context>server config</context><context>virtual host</context>
2891 <context>directory</context><context>.htaccess</context>
2893 <override>FileInfo</override>
2896 <p>The <directive>SetOutputFilter</directive> directive sets the filters
2897 which will process responses from the server before they are
2898 sent to the client. This is in addition to any filters defined
2899 elsewhere, including the
2900 <directive module="mod_mime">AddOutputFilter</directive>
2903 <p>For example, the following configuration will process all files
2904 in the <code>/www/data/</code> directory for server-side
2908 <Directory /www/data/><br />
2910 SetOutputFilter INCLUDES<br />
2915 <p>If more than one filter is specified, they must be separated
2916 by semicolons in the order in which they should process the
2919 <seealso><a href="../filter.html">Filters</a> documentation</seealso>
2920 </directivesynopsis>
2923 <name>TimeOut</name>
2924 <description>Amount of time the server will wait for
2925 certain events before failing a request</description>
2926 <syntax>TimeOut <var>seconds</var></syntax>
2927 <default>TimeOut 300</default>
2928 <contextlist><context>server config</context></contextlist>
2931 <p>The <directive>TimeOut</directive> directive currently defines
2932 the amount of time Apache will wait for three things:</p>
2935 <li>The total amount of time it takes to receive a GET
2938 <li>The amount of time between receipt of TCP packets on a
2939 POST or PUT request.</li>
2941 <li>The amount of time between ACKs on transmissions of TCP
2942 packets in responses.</li>
2945 <p>We plan on making these separately configurable at some point
2946 down the road. The timer used to default to 1200 before 1.2,
2947 but has been lowered to 300 which is still far more than
2948 necessary in most situations. It is not set any lower by
2949 default because there may still be odd places in the code where
2950 the timer is not reset when a packet is sent. </p>
2952 </directivesynopsis>
2955 <name>UseCanonicalName</name>
2956 <description>Configures how the server determines its own name and
2958 <syntax>UseCanonicalName On|Off|DNS</syntax>
2959 <default>UseCanonicalName On</default>
2960 <contextlist><context>server config</context><context>virtual host</context>
2961 <context>directory</context></contextlist>
2964 <p>In many situations Apache must construct a <em>self-referential</em>
2965 URL -- that is, a URL that refers back to the same server. With
2966 <code>UseCanonicalName On</code> Apache will use the hostname and port
2967 specified in the <directive module="core">ServerName</directive>
2968 directive to construct the canonical name for the server. This name
2969 is used in all self-referential URLs, and for the values of
2970 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in CGIs.</p>
2972 <p>With <code>UseCanonicalName Off</code> Apache will form
2973 self-referential URLs using the hostname and port supplied by
2974 the client if any are supplied (otherwise it will use the
2975 canonical name, as defined above). These values are the same
2976 that are used to implement <a
2977 href="../vhosts/name-based.html">name based virtual hosts</a>,
2978 and are available with the same clients. The CGI variables
2979 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
2980 constructed from the client supplied values as well.</p>
2982 <p>An example where this may be useful is on an intranet server
2983 where you have users connecting to the machine using short
2984 names such as <code>www</code>. You'll notice that if the users
2985 type a shortname, and a URL which is a directory, such as
2986 <code>http://www/splat</code>, <em>without the trailing
2987 slash</em> then Apache will redirect them to
2988 <code>http://www.domain.com/splat/</code>. If you have
2989 authentication enabled, this will cause the user to have to
2990 authenticate twice (once for <code>www</code> and once again
2991 for <code>www.domain.com</code> -- see <a
2992 href="http://httpd.apache.org/docs/misc/FAQ.html#prompted-twice">the
2993 FAQ on this subject for more information</a>). But if
2994 <directive>UseCanonicalName</directive> is set <code>Off</code>, then
2995 Apache will redirect to <code>http://www/splat/</code>.</p>
2997 <p>There is a third option, <code>UseCanonicalName DNS</code>,
2998 which is intended for use with mass IP-based virtual hosting to
2999 support ancient clients that do not provide a
3000 <code>Host:</code> header. With this option Apache does a
3001 reverse DNS lookup on the server IP address that the client
3002 connected to in order to work out self-referential URLs.</p>
3004 <note type="warning"><title>Warning</title>
3005 <p>If CGIs make assumptions about the values of <code>SERVER_NAME</code>
3006 they may be broken by this option. The client is essentially free
3007 to give whatever value they want as a hostname. But if the CGI is
3008 only using <code>SERVER_NAME</code> to construct self-referential URLs
3009 then it should be just fine.</p>
3012 <seealso><directive module="core">ServerName</directive></seealso>
3013 <seealso><directive module="mpm_common">Listen</directive></seealso>
3014 </directivesynopsis>
3016 <directivesynopsis type="section">
3017 <name>VirtualHost</name>
3018 <description>Contains directives that apply only to a specific
3019 hostname or IP address</description>
3020 <syntax><VirtualHost
3021 <var>addr</var>[:<var>port</var>] [<var>addr</var>[:<var>port</var>]]
3022 ...> ... </VirtualHost></syntax>
3023 <contextlist><context>server config</context></contextlist>
3026 <p><directive type="section">VirtualHost</directive> and
3027 <code></VirtualHost></code> are used to enclose a group of
3028 directives that will apply only to a particular virtual host. Any
3029 directive that is allowed in a virtual host context may be
3030 used. When the server receives a request for a document on a
3031 particular virtual host, it uses the configuration directives
3032 enclosed in the <directive type="section">VirtualHost</directive>
3033 section. <var>Addr</var> can be:</p>
3036 <li>The IP address of the virtual host;</li>
3038 <li>A fully qualified domain name for the IP address of the
3041 <li>The character <code>*</code>, which is used only in combination with
3042 <code>NameVirtualHost *</code> to match all IP addresses; or</li>
3044 <li>The string <code>_default_</code>, which is used only
3045 with IP virtual hosting to catch unmatched IP addresses.</li>
3048 <example><title>Example</title>
3049 <VirtualHost 10.1.2.3><br />
3051 ServerAdmin webmaster@host.foo.com<br />
3052 DocumentRoot /www/docs/host.foo.com<br />
3053 ServerName host.foo.com<br />
3054 ErrorLog logs/host.foo.com-error_log<br />
3055 TransferLog logs/host.foo.com-access_log<br />
3057 </VirtualHost>
3061 <p>IPv6 addresses must be specified in square brackets because
3062 the optional port number could not be determined otherwise. An
3063 IPv6 example is shown below:</p>
3066 <VirtualHost [fe80::a00:20ff:fea7:ccea]><br />
3068 ServerAdmin webmaster@host.example.com<br />
3069 DocumentRoot /www/docs/host.example.com<br />
3070 ServerName host.example.com<br />
3071 ErrorLog logs/host.example.com-error_log<br />
3072 TransferLog logs/host.example.com-access_log<br />
3074 </VirtualHost>
3077 <p>Each Virtual Host must correspond to a different IP address,
3078 different port number or a different host name for the server,
3079 in the former case the server machine must be configured to
3080 accept IP packets for multiple addresses. (If the machine does
3081 not have multiple network interfaces, then this can be
3082 accomplished with the <code>ifconfig alias</code> command -- if
3083 your OS supports it).</p>
3085 <note><title>Note</title>
3086 <p>The use of <directive type="section">VirtualHost</directive> does
3087 <strong>not</strong> affect what addresses Apache listens on. You
3088 may need to ensure that Apache is listening on the correct addresses
3089 using <directive module="mpm_common">Listen</directive>.</p>
3092 <p>When using IP-based virtual hosting, the special name
3093 <code>_default_</code> can be specified in
3094 which case this virtual host will match any IP address that is
3095 not explicitly listed in another virtual host. In the absence
3096 of any <code>_default_</code> virtual host the "main" server config,
3097 consisting of all those definitions outside any VirtualHost
3098 section, is used when no IP-match occurs. (But note that any IP
3099 address that matches a <directive
3100 module="core">NameVirtualHost</directive> directive will use neither
3101 the "main" server config nor the <code>_default_</code> virtual host.
3102 See the <a href="../vhosts/name-based.html">name-based virtual hosting</a>
3103 documentation for further details.)</p>
3105 <p>You can specify a <code>:port</code> to change the port that is
3106 matched. If unspecified then it defaults to the same port as the
3107 most recent <directive module="mpm_common">Listen</directive>
3108 statement of the main server. You may also specify <code>:*</code>
3109 to match all ports on that address. (This is recommended when used
3110 with <code>_default_</code>.)</p>
3112 <note type="warning"><title>Security</title>
3113 <p>See the <a href="../misc/security_tips.html">security tips</a>
3114 document for details on why your security could be compromised if the
3115 directory where log files are stored is writable by anyone other
3116 than the user that starts the server.</p>
3119 <seealso><a href="../vhosts/">Apache Virtual Host documentation</a></seealso>
3120 <seealso><a href="../dns-caveats.html">Issues Regarding DNS and
3121 Apache</a></seealso>
3122 <seealso><a href="../bind.html">Setting
3123 which addresses and ports Apache uses</a></seealso>
3124 <seealso><a href="../sections.html">How <Directory>, <Location>
3125 and <Files> sections work</a> for an explanation of how these
3126 different sections are combined when a request is received</seealso>
3127 </directivesynopsis>