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23 <modulesynopsis metafile="mod_proxy.xml.meta">
25 <name>mod_proxy</name>
26 <description>HTTP/1.1 proxy/gateway server</description>
27 <status>Extension</status>
28 <sourcefile>mod_proxy.c</sourcefile>
29 <identifier>proxy_module</identifier>
32 <note type="warning"><title>Warning</title>
33 <p>Do not enable proxying with <directive module="mod_proxy"
34 >ProxyRequests</directive> until you have <a href="#access"
35 >secured your server</a>. Open proxy servers are dangerous both to your
36 network and to the Internet at large.</p>
39 <p>This module implements a proxy/gateway for Apache. It implements
40 proxying capability for <code>AJP13</code> (Apache JServe Protocol
41 version 1.3), <code>FTP</code>, <code>CONNECT</code> (for SSL),
42 <code>HTTP/0.9</code>, <code>HTTP/1.0</code>, and <code>HTTP/1.1</code>.
43 The module can be configured to connect to other proxy modules for these
44 and other protocols.</p>
46 <p>Apache's proxy features are divided into several modules in
47 addition to <module>mod_proxy</module>:
48 <module>mod_proxy_http</module>, <module>mod_proxy_ftp</module>,
49 <module>mod_proxy_ajp</module>, <module>mod_proxy_balancer</module>,
50 and <module>mod_proxy_connect</module>. Thus, if you want to use
51 one or more of the particular proxy functions, load
52 <module>mod_proxy</module> <em>and</em> the appropriate module(s)
53 into the server (either statically at compile-time or dynamically
54 via the <directive module="mod_so">LoadModule</directive>
57 <p>In addition, extended features are provided by other modules.
58 Caching is provided by <module>mod_cache</module> and related
59 modules. The ability to contact remote servers using the SSL/TLS
60 protocol is provided by the <code>SSLProxy*</code> directives of
61 <module>mod_ssl</module>. These additional modules will need
62 to be loaded and configured to take advantage of these features.</p>
64 <seealso><module>mod_cache</module></seealso>
65 <seealso><module>mod_proxy_http</module></seealso>
66 <seealso><module>mod_proxy_ftp</module></seealso>
67 <seealso><module>mod_proxy_connect</module></seealso>
68 <seealso><module>mod_proxy_balancer</module></seealso>
69 <seealso><module>mod_ssl</module></seealso>
71 <section id="forwardreverse"><title>Forward Proxies and Reverse
72 Proxies/Gateways</title>
73 <p>Apache can be configured in both a <dfn>forward</dfn> and
74 <dfn>reverse</dfn> proxy (also known as <dfn>gateway</dfn>) mode.</p>
76 <p>An ordinary <dfn>forward proxy</dfn> is an intermediate
77 server that sits between the client and the <em>origin
78 server</em>. In order to get content from the origin server,
79 the client sends a request to the proxy naming the origin server
80 as the target and the proxy then requests the content from the
81 origin server and returns it to the client. The client must be
82 specially configured to use the forward proxy to access other
85 <p>A typical usage of a forward proxy is to provide Internet
86 access to internal clients that are otherwise restricted by a
87 firewall. The forward proxy can also use caching (as provided
88 by <module>mod_cache</module>) to reduce network usage.</p>
90 <p>The forward proxy is activated using the <directive
91 module="mod_proxy">ProxyRequests</directive> directive. Because
92 forward proxies allow clients to access arbitrary sites through
93 your server and to hide their true origin, it is essential that
94 you <a href="#access">secure your server</a> so that only
95 authorized clients can access the proxy before activating a
98 <p>A <dfn>reverse proxy</dfn> (or <dfn>gateway</dfn>), by
99 contrast, appears to the client just like an ordinary web
100 server. No special configuration on the client is necessary.
101 The client makes ordinary requests for content in the name-space
102 of the reverse proxy. The reverse proxy then decides where to
103 send those requests, and returns the content as if it was itself
106 <p>A typical usage of a reverse proxy is to provide Internet
107 users access to a server that is behind a firewall. Reverse
108 proxies can also be used to balance load among several back-end
109 servers, or to provide caching for a slower back-end server.
110 In addition, reverse proxies can be used simply to bring
111 several servers into the same URL space.</p>
113 <p>A reverse proxy is activated using the <directive
114 module="mod_proxy">ProxyPass</directive> directive or the
115 <code>[P]</code> flag to the <directive
116 module="mod_rewrite">RewriteRule</directive> directive. It is
117 <strong>not</strong> necessary to turn <directive
118 module="mod_proxy">ProxyRequests</directive> on in order to
119 configure a reverse proxy.</p>
120 </section> <!-- /forwardreverse -->
122 <section id="examples"><title>Basic Examples</title>
124 <p>The examples below are only a very basic idea to help you
125 get started. Please read the documentation on the individual
128 <p>In addition, if you wish to have caching enabled, consult
129 the documentation from <module>mod_cache</module>.</p>
131 <example><title>Forward Proxy</title>
132 ProxyRequests On<br />
135 <Proxy *><br />
137 Order deny,allow<br />
139 Allow from internal.example.com<br />
144 <example><title>Reverse Proxy</title>
145 ProxyRequests Off<br />
147 <Proxy *><br />
149 Order deny,allow<br />
154 ProxyPass /foo http://foo.example.com/bar<br />
155 ProxyPassReverse /foo http://foo.example.com/bar
157 </section> <!-- /examples -->
160 <section id="access"><title>Controlling access to your proxy</title>
161 <p>You can control who can access your proxy via the <directive
162 module="mod_proxy" type="section">Proxy</directive> control block as in
163 the following example:</p>
166 <Proxy *><br />
168 Order Deny,Allow<br />
170 Allow from 192.168.0<br />
175 <p>For more information on access control directives, see
176 <module>mod_authz_host</module>.</p>
178 <p>Strictly limiting access is essential if you are using a
179 forward proxy (using the <directive
180 module="mod_proxy">ProxyRequests</directive> directive).
181 Otherwise, your server can be used by any client to access
182 arbitrary hosts while hiding his or her true identity. This is
183 dangerous both for your network and for the Internet at large.
184 When using a reverse proxy (using the <directive
185 module="mod_proxy">ProxyPass</directive> directive with
186 <code>ProxyRequests Off</code>), access control is less
187 critical because clients can only contact the hosts that you
188 have specifically configured.</p>
190 <p><strong>See Also</strong> the <a href="mod_proxy_http.html#env"
191 >Proxy-Chain-Auth</a> environment variable.</p>
193 </section> <!-- /access -->
195 <section id="startup"><title>Slow Startup</title>
196 <p>If you're using the <directive module="mod_proxy"
197 >ProxyBlock</directive> directive, hostnames' IP addresses are looked up
198 and cached during startup for later match test. This may take a few
199 seconds (or more) depending on the speed with which the hostname lookups
201 </section> <!-- /startup -->
203 <section id="intranet"><title>Intranet Proxy</title>
204 <p>An Apache proxy server situated in an intranet needs to forward
205 external requests through the company's firewall (for this, configure
206 the <directive module="mod_proxy">ProxyRemote</directive> directive
207 to forward the respective <var>scheme</var> to the firewall proxy).
208 However, when it has to
209 access resources within the intranet, it can bypass the firewall when
210 accessing hosts. The <directive module="mod_proxy">NoProxy</directive>
211 directive is useful for specifying which hosts belong to the intranet and
212 should be accessed directly.</p>
214 <p>Users within an intranet tend to omit the local domain name from their
215 WWW requests, thus requesting "http://somehost/" instead of
216 <code>http://somehost.example.com/</code>. Some commercial proxy servers
217 let them get away with this and simply serve the request, implying a
218 configured local domain. When the <directive module="mod_proxy"
219 >ProxyDomain</directive> directive is used and the server is <a
220 href="#proxyrequests">configured for proxy service</a>, Apache can return
221 a redirect response and send the client to the correct, fully qualified,
222 server address. This is the preferred method since the user's bookmark
223 files will then contain fully qualified hosts.</p>
224 </section> <!-- /intranet -->
226 <section id="envsettings"><title>Protocol Adjustments</title>
227 <p>For circumstances where <module>mod_proxy</module> is sending
228 requests to an origin server that doesn't properly implement
229 keepalives or HTTP/1.1, there are two <a
230 href="../env.html">environment variables</a> that can force the
231 request to use HTTP/1.0 with no keepalive. These are set via the
232 <directive module="mod_env">SetEnv</directive> directive.</p>
234 <p>These are the <code>force-proxy-request-1.0</code> and
235 <code>proxy-nokeepalive</code> notes.</p>
238 <Location /buggyappserver/><br />
240 ProxyPass http://buggyappserver:7001/foo/<br />
241 SetEnv force-proxy-request-1.0 1<br />
242 SetEnv proxy-nokeepalive 1<br />
247 </section> <!-- /envsettings -->
249 <section id="request-bodies"><title>Request Bodies</title>
251 <p>Some request methods such as POST include a request body.
252 The HTTP protocol requires that requests which include a body
253 either use chunked transfer encoding or send a
254 <code>Content-Length</code> request header. When passing these
255 requests on to the origin server, <module>mod_proxy_http</module>
256 will always attempt to send the <code>Content-Length</code>. But
257 if the body is large and the original request used chunked
258 encoding, then chunked encoding may also be used in the upstream
259 request. You can control this selection using <a
260 href="../env.html">environment variables</a>. Setting
261 <code>proxy-sendcl</code> ensures maximum compatibility with
262 upstream servers by always sending the
263 <code>Content-Length</code>, while setting
264 <code>proxy-sendchunked</code> minimizes resource usage by using
265 chunked encoding.</p>
267 </section> <!-- /request-bodies -->
269 <section id="x-headers"><title>Reverse Proxy Request Headers</title>
271 <p>When acting in a reverse-proxy mode (using the <directive
272 module="mod_proxy">ProxyPass</directive> directive, for example),
273 <module>mod_proxy_http</module> adds several request headers in
274 order to pass information to the origin server. These headers
278 <dt><code>X-Forwarded-For</code></dt>
279 <dd>The IP address of the client.</dd>
280 <dt><code>X-Forwarded-Host</code></dt>
281 <dd>The original host requested by the client in the <code>Host</code>
282 HTTP request header.</dd>
283 <dt><code>X-Forwarded-Server</code></dt>
284 <dd>The hostname of the proxy server.</dd>
287 <p>Be careful when using these headers on the origin server, since
288 they will contain more than one (comma-separated) value if the
289 original request already contained one of these headers. For
290 example, you can use <code>%{X-Forwarded-For}i</code> in the log
291 format string of the origin server to log the original clients IP
292 address, but you may get more than one address if the request
293 passes through several proxies.</p>
295 <p>See also the <directive
296 module="mod_proxy">ProxyPreserveHost</directive> and <directive
297 module="mod_proxy">ProxyVia</directive> directives, which control
298 other request headers.</p>
300 </section> <!--/x-headers -->
303 <directivesynopsis type="section">
305 <description>Container for directives applied to proxied resources</description>
306 <syntax><Proxy <var>wildcard-url</var>> ...</Proxy></syntax>
307 <contextlist><context>server config</context><context>virtual host</context>
311 <p>Directives placed in <directive type="section">Proxy</directive>
312 sections apply only to matching proxied content. Shell-style wildcards are
315 <p>For example, the following will allow only hosts in
316 <code>yournetwork.example.com</code> to access content via your proxy
320 <Proxy *><br />
322 Order Deny,Allow<br />
324 Allow from yournetwork.example.com<br />
329 <p>The following example will process all files in the <code>foo</code>
330 directory of <code>example.com</code> through the <code>INCLUDES</code>
331 filter when they are sent through the proxy server:</p>
334 <Proxy http://example.com/foo/*><br />
336 SetOutputFilter INCLUDES<br />
345 <name>ProxyBadHeader</name>
346 <description>Determines how to handle bad header lines in a
347 response</description>
348 <syntax>ProxyBadHeader IsError|Ignore|StartBody</syntax>
349 <default>ProxyBadHeader IsError</default>
350 <contextlist><context>server config</context><context>virtual host</context>
352 <compatibility>Available in Apache 2.0.44 and later</compatibility>
355 <p>The <directive>ProxyBadHeader</directive> directive determines the
356 behaviour of <module>mod_proxy</module> if it receives syntactically invalid
357 header lines (<em>i.e.</em> containing no colon). The following arguments
361 <dt><code>IsError</code></dt>
362 <dd>Abort the request and end up with a 502 (Bad Gateway) response. This is
363 the default behaviour.</dd>
365 <dt><code>Ignore</code></dt>
366 <dd>Treat bad header lines as if they weren't sent.</dd>
368 <dt><code>StartBody</code></dt>
369 <dd>When receiving the first bad header line, finish reading the headers and
370 treat the remainder as body. This helps to work around buggy backend servers
371 which forget to insert an empty line between the headers and the body.</dd>
377 <name>ProxyFtpDirCharset</name>
378 <description>Define the character set for proxied FTP listings</description>
379 <syntax>ProxyFtpDirCharset <var>character set</var></syntax>
380 <default>ProxyFtpDirCharset ISO-8859-1</default>
381 <contextlist><context>server config</context><context>virtual host</context>
382 <context>directory</context></contextlist>
383 <compatibility>Available in Apache 2.2.7 and later</compatibility>
386 <p>The <directive>ProxyFtpDirCharset</directive> directive defines the
387 character set to be set for FTP directory listings in HTML generated by
388 <module>mod_proxy_ftp</module>.</p>
392 <directivesynopsis type="section">
393 <name>ProxyMatch</name>
394 <description>Container for directives applied to regular-expression-matched
395 proxied resources</description>
396 <syntax><ProxyMatch <var>regex</var>> ...</ProxyMatch></syntax>
397 <contextlist><context>server config</context><context>virtual host</context>
401 <p>The <directive type="section">ProxyMatch</directive> directive is
402 identical to the <directive module="mod_proxy"
403 type="section">Proxy</directive> directive, except it matches URLs
404 using <glossary ref="regex">regular expressions</glossary>.</p>
409 <name>ProxyPreserveHost</name>
410 <description>Use incoming Host HTTP request header for proxy
411 request</description>
412 <syntax>ProxyPreserveHost On|Off</syntax>
413 <default>ProxyPreserveHost Off</default>
414 <contextlist><context>server config</context><context>virtual host</context>
416 <compatibility>Available in Apache 2.0.31 and later.</compatibility>
419 <p>When enabled, this option will pass the Host: line from the incoming
420 request to the proxied host, instead of the hostname specified in the
421 <directive>ProxyPass</directive> line.</p>
423 <p>This option should normally be turned <code>Off</code>. It is mostly
424 useful in special configurations like proxied mass name-based virtual
425 hosting, where the original Host header needs to be evaluated by the
431 <name>ProxyRequests</name>
432 <description>Enables forward (standard) proxy requests</description>
433 <syntax>ProxyRequests On|Off</syntax>
434 <default>ProxyRequests Off</default>
435 <contextlist><context>server config</context><context>virtual host</context>
439 <p>This allows or prevents Apache from functioning as a forward proxy
440 server. (Setting ProxyRequests to <code>Off</code> does not disable use of
441 the <directive module="mod_proxy">ProxyPass</directive> directive.)</p>
443 <p>In a typical reverse proxy or gateway configuration, this
444 option should be set to
445 <code>Off</code>.</p>
447 <p>In order to get the functionality of proxying HTTP or FTP sites, you
448 need also <module>mod_proxy_http</module> or <module>mod_proxy_ftp</module>
449 (or both) present in the server.</p>
451 <note type="warning"><title>Warning</title>
452 <p>Do not enable proxying with <directive
453 module="mod_proxy">ProxyRequests</directive> until you have <a
454 href="#access">secured your server</a>. Open proxy servers are dangerous
455 both to your network and to the Internet at large.</p>
458 <seealso><a href="#forwardreverse">Forward and Reverse Proxies/Gateways</a></seealso>
462 <name>ProxyRemote</name>
463 <description>Remote proxy used to handle certain requests</description>
464 <syntax>ProxyRemote <var>match</var> <var>remote-server</var></syntax>
465 <contextlist><context>server config</context><context>virtual host</context>
469 <p>This defines remote proxies to this proxy. <var>match</var> is either the
470 name of a URL-scheme that the remote server supports, or a partial URL
471 for which the remote server should be used, or <code>*</code> to indicate
472 the server should be contacted for all requests. <var>remote-server</var> is
473 a partial URL for the remote server. Syntax:</p>
476 <dfn>remote-server</dfn> =
477 <var>scheme</var>://<var>hostname</var>[:<var>port</var>]
480 <p><var>scheme</var> is effectively the protocol that should be used to
481 communicate with the remote server; only <code>http</code> is supported by
484 <example><title>Example</title>
485 ProxyRemote http://goodguys.example.com/ http://mirrorguys.example.com:8000<br />
486 ProxyRemote * http://cleverproxy.localdomain<br />
487 ProxyRemote ftp http://ftpproxy.mydomain:8080
490 <p>In the last example, the proxy will forward FTP requests, encapsulated
491 as yet another HTTP proxy request, to another proxy which can handle
494 <p>This option also supports reverse proxy configuration - a backend
495 webserver can be embedded within a virtualhost URL space even if that
496 server is hidden by another forward proxy.</p>
501 <name>ProxyRemoteMatch</name>
502 <description>Remote proxy used to handle requests matched by regular
503 expressions</description>
504 <syntax>ProxyRemoteMatch <var>regex</var> <var>remote-server</var></syntax>
505 <contextlist><context>server config</context><context>virtual host</context>
509 <p>The <directive>ProxyRemoteMatch</directive> is identical to the
510 <directive module="mod_proxy">ProxyRemote</directive> directive, except the
511 first argument is a <glossary ref="regex">regular expression</glossary>
512 match against the requested URL.</p>
517 <name>BalancerMember</name>
518 <description>Add a member to a load balancing group</description>
519 <syntax>BalancerMember <var>url</var> [<var
520 >key=value [key=value ...]]</var></syntax>
521 <contextlist><context>directory</context>
523 <compatibility>BalancerMember is only available in Apache 2.2
524 and later.</compatibility>
526 <p>This directive adds a member to a load balancing group. It must be used
527 within a <code><Proxy <var>balancer://</var>...></code> container
528 directive, and can take any of the parameters available to
529 <directive module="mod_proxy">ProxyPass</directive> directives.</p>
530 <p>One additional parameter is available only to <directive
531 module="mod_proxy">BalancerMember</directive> directives:
532 <var>loadfactor</var>. This is the member load factor - a number between 1
533 (default) and 100, which defines the weighted load to be applied to the
534 member in question.</p>
539 <name>ProxySet</name>
540 <description>Set various Proxy balancer or member parameters</description>
541 <syntax>ProxySet <var>url</var> <var>key=value [key=value ...]</var></syntax>
542 <contextlist><context>directory</context>
544 <compatibility>ProxySet is only available in Apache 2.2
545 and later.</compatibility>
547 <p>This directive is used as an alternate method of setting any of the
548 parameters available to Proxy balancers and workers normally done via the
549 <directive module="mod_proxy">ProxyPass</directive> directive. If used
550 within a <code><Proxy <var>balancer url|worker url</var>></code>
551 container directive, the <var>url</var> argument is not required. As a side
552 effect the respective balancer or worker gets created. This can be useful
553 when doing reverse proxying via a
554 <directive module="mod_rewrite">RewriteRule</directive> instead of a
555 <directive module="mod_proxy">ProxyPass</directive> directive.</p>
558 <Proxy balancer://hotcluster><br />
560 BalancerMember http://www2.example.com:8009 loadfactor=1<br />
561 BalancerMember http://www3.example.com:8009 loadfactor=2<br />
562 ProxySet lbmethod=bytraffic<br />
568 <Proxy http://backend><br />
570 ProxySet keepalive=On<br />
576 ProxySet balancer://foo lbmethod=bytraffic timeout=15
580 ProxySet ajp://backend:7001 timeout=15
583 <note type="warning"><title>Warning</title>
584 <p>Keep in mind that the same parameter key can have a different meaning
585 depending whether it is applied to a balancer or a worker as shown by the two
586 examples above regarding timeout.</p>
593 <name>ProxyPass</name>
594 <description>Maps remote servers into the local server URL-space</description>
595 <syntax>ProxyPass [<var>path</var>] !|<var>url</var> [<var>key=value</var>
596 <var>[key=value</var> ...]] [nocanon] [interpolate]</syntax>
597 <contextlist><context>server config</context><context>virtual host</context>
598 <context>directory</context>
602 <p>This directive allows remote servers to be mapped into the
603 space of the local server; the local server does not act as a
604 proxy in the conventional sense, but appears to be a mirror of the
605 remote server. The local server is often called a <dfn>reverse
606 proxy</dfn> or <dfn>gateway</dfn>. The <var>path</var> is the name of
607 a local virtual path; <var>url</var> is a partial URL for the
608 remote server and cannot include a query string.</p>
610 <note type="warning">The <directive
611 module="mod_proxy">ProxyRequests</directive> directive should
612 usually be set <strong>off</strong> when using
613 <directive>ProxyPass</directive>.</note>
615 <p>Suppose the local server has address <code>http://example.com/</code>;
619 ProxyPass /mirror/foo/ http://backend.example.com/
622 <p>will cause a local request for
623 <code>http://example.com/mirror/foo/bar</code> to be internally converted
624 into a proxy request to <code>http://backend.example.com/bar</code>.</p>
626 <note type="warning">
627 <p>If the first argument ends with a trailing <strong>/</strong>, the second
628 argument should also end with a trailing <strong>/</strong> and vice
629 versa. Otherwise the resulting requests to the backend may miss some
630 needed slashes and do not deliver the expected results.
634 <p>The <code>!</code> directive is useful in situations where you don't want
635 to reverse-proxy a subdirectory, <em>e.g.</em></p>
638 ProxyPass /mirror/foo/i !<br />
639 ProxyPass /mirror/foo http://backend.example.com
642 <p>will proxy all requests to <code>/mirror/foo</code> to
643 <code>backend.example.com</code> <em>except</em> requests made to
644 <code>/mirror/foo/i</code>.</p>
646 <note><title>Note</title>
647 <p>Order is important: exclusions must come <em>before</em> the
648 general <directive>ProxyPass</directive> directive.</p>
651 <p>As of Apache 2.1, the ability to use pooled connections to a backend
652 server is available. Using the <code>key=value</code> parameters it is
653 possible to tune this connection pooling. The default for a <code>Hard
654 Maximum</code> for the number of connections is the number of threads per
655 process in the active MPM. In the Prefork MPM, this is always 1, while with
656 the Worker MPM it is controlled by the
657 <directive>ThreadsPerChild</directive>.</p>
659 <p>Setting <code>min</code> will determine how many connections will always
660 be open to the backend server. Upto the Soft Maximum or <code>smax</code>
661 number of connections will be created on demand. Any connections above
662 <code>smax</code> are subject to a time to live or <code>ttl</code>. Apache
663 will never create more than the Hard Maximum or <code>max</code> connections
664 to the backend server.</p>
667 ProxyPass /example http://backend.example.com smax=5 max=20 ttl=120 retry=300
671 <tr><th>Parameter</th>
673 <th>Description</th></tr>
676 <td>Minimum number of connections that will always
677 be open to the backend server.</td></tr>
680 <td>Hard Maximum number of connections that will be
681 allowed to the backend server. The default for a Hard Maximum
682 for the number of connections is the number of threads per process in the
683 active MPM. In the Prefork MPM, this is always 1, while with the Worker MPM
684 it is controlled by the <directive>ThreadsPerChild</directive>.
685 Apache will never create more than the Hard Maximum connections
686 to the backend server.</td></tr>
689 <td>Upto the Soft Maximum
690 number of connections will be created on demand. Any connections above
691 <code>smax</code> are subject to a time to live or <code>ttl</code>.
695 <td>If set this will be the maximum time to wait for a free
696 connection in the connection pool, in milliseconds. If there are no free
697 connections in the pool the Apache will return <code>SERVER_BUSY</code>
698 status to the client.
700 <tr><td>connectiontimeout</td>
702 <td>Connect timeout in seconds.
703 The number of seconds Apache waits for the creation of a connection to
704 the backend to complete. By adding a postfix of ms the timeout can be
705 also set in milliseconds.
707 <tr><td>disablereuse</td>
709 <td>This parameter should be used when you want to force mod_proxy
710 to immediately close a connection to the backend after being used, and
711 thus, disable its persistent connection and pool for that backend.
712 This helps in various situations where a firewall between Apache and
713 the backend server (regardless of protocol) tends to silently
714 drop connections or when backends themselves may be under round-
715 robin DNS. To disable connection pooling reuse,
716 set this property value to <code>On</code>.
718 <tr><td>flushpackets</td>
720 <td>Determines whether the proxy module will auto-flush the output
721 brigade after each "chunk" of data. 'off' means that it will flush
722 only when needed, 'on' means after each chunk is sent and
723 'auto' means poll/wait for a period of time and flush if
724 no input has been received for 'flushwait' milliseconds.
725 Currently this is in effect only for AJP.
727 <tr><td>flushwait</td>
729 <td>The time to wait for additional input, in milliseconds, before
730 flushing the output brigade if 'flushpackets' is 'auto'.
732 <tr><td>keepalive</td>
734 <td>This parameter should be used when you have a firewall between your
735 Apache and the backend server, who tend to drop inactive connections.
736 This flag will tell the Operating System to send <code>KEEP_ALIVE</code>
737 messages on inactive connections (interval depends on global OS settings,
738 generally 120ms), and thus prevent the firewall to drop the connection.
739 To enable keepalive set this property value to <code>On</code>.
743 <td>Sets the load balancer cluster set that the worker is a member
744 of. The load balancer will try all members of a lower numbered
745 lbset before trying higher numbered ones.
749 <td>Ping property tells webserver to send a <code>CPING</code>
750 request on ajp13 connection before forwarding a request.
751 The parameter is the delay in seconds to wait for the
752 <code>CPONG</code> reply.
753 This features has been added to avoid problem with hung and
754 busy Tomcat's and require ajp13 ping/pong support which has
755 been implemented on Tomcat 3.3.2+, 4.1.28+ and 5.0.13+.
756 This will increase the network traffic during the normal operation
757 which could be an issue, but it will lower the
758 traffic in case some of the cluster nodes are down or busy.
759 Currently this has an effect only for AJP.
760 By adding a postfix of ms the delay can be also set in
763 <tr><td>redirect</td>
765 <td>Redirection Route of the worker. This value is usually
766 set dynamically to enable safe removal of the node from
767 the cluster. If set all requests without session id will be
768 redirected to the BalancerMember that has route parametar
773 <td>Connection pool worker retry timeout in seconds.
774 If the connection pool worker to the backend server is in the error state,
775 Apache will not forward any requests to that server until the timeout
776 expires. This enables to shut down the backend server for maintenance,
777 and bring it back online later. A value of 0 means always retry workers
778 in an error state with no timeout.
782 <td>Route of the worker when used inside load balancer.
783 The route is a value appended to session id.
787 <td>Single letter value defining the initial status of
788 this worker: 'D' is disabled, 'S' is stopped, 'I' is ignore-errors,
789 'H' is hot-standby and 'E' is in an error state. Status
790 can be set (which is the default) by prepending with '+' or
791 cleared by prepending with '-'.
792 Thus, a setting of 'S-E' sets this worker to Stopped and
793 clears the in-error flag.
796 <td><directive module="mod_proxy">ProxyTimeout</directive></td>
797 <td>Connection timeout in seconds.
798 The number of seconds Apache waits for data sent by / to the backend.
802 <td>Time To Live for the inactive connections above the
803 <code>smax</code> connections in seconds. Apache will close all
804 connections that has not been used inside that time period.
809 <p>If the Proxy directive scheme starts with the
810 <code>balancer://</code> then a virtual worker that does not really
811 communicate with the backend server will be created. Instead it is responsible
812 for the management of several "real" workers. In that case the special set of
813 parameters can be add to this virtual worker. See <module>mod_proxy_balancer</module>
814 for more information about how the balancer works.
817 <tr><th>Parameter</th>
819 <th>Description</th></tr>
820 <tr><td>lbmethod</td>
822 <td>Balancer load-balance method. Select the load-balancing scheduler
823 method to use. Either <code>byrequests</code>, to perform weighted
824 request counting, <code>bytraffic</code>, to perform weighted
825 traffic byte count balancing, or <code>bybusyness</code>, to perform
826 pending request balancing. Default is <code>byrequests</code>.
828 <tr><td>maxattempts</td>
830 <td>Maximum number of failover attempts before giving up.
832 <tr><td>nofailover</td>
834 <td>If set to <code>On</code> the session will break if the worker is in
835 error state or disabled. Set this value to On if backend servers do not
836 support session replication.
838 <tr><td>stickysession</td>
840 <td>Balancer sticky session name. The value is usually set to something
841 like <code>JSESSIONID</code> or <code>PHPSESSIONID</code>,
842 and it depends on the backend application server that support sessions.
843 If the backend application server uses different name for cookies
844 and url encoded id (like servlet containers) use | to to separate them.
845 The first part is for the cookie the second for the path.
847 <tr><td>scolonpathdelim</td>
849 <td>If set to <code>On</code> the semi-colon character ';' will be
850 used as an additional sticky session path deliminator/separator. This
851 is mainly used to emulate mod_jk's behavior when dealing with paths such
852 as <code>JSESSIONID=6736bcf34;foo=aabfa</code>
856 <td>Balancer timeout in seconds. If set this will be the maximum time
857 to wait for a free worker. Default is not to wait.
861 <p>A sample balancer setup</p>
863 ProxyPass /special-area http://special.example.com/ smax=5 max=10<br />
864 ProxyPass / balancer://mycluster/ stickysession=JSESSIONID|jsessionid nofailover=On<br />
865 <Proxy balancer://mycluster><br />
867 BalancerMember http://1.2.3.4:8009<br />
868 BalancerMember http://1.2.3.5:8009 smax=10<br />
869 # Less powerful server, don't send as many requests there<br />
870 BalancerMember http://1.2.3.6:8009 smax=1 loadfactor=20<br />
875 <p>Setting up a hot-standby, that will only be used if no other
876 members are available</p>
878 ProxyPass / balancer://hotcluster/ <br />
879 <Proxy balancer://hotcluster><br />
881 BalancerMember http://1.2.3.4:8009 loadfactor=1<br />
882 BalancerMember http://1.2.3.5:8009 loadfactor=2<br />
883 # The below is the hot standby<br />
884 BalancerMember http://1.2.3.6:8009 status=+H<br />
885 ProxySet lbmethod=bytraffic
890 <p>Normally, mod_proxy will canonicalise ProxyPassed URLs.
891 But this may be incompatible with some backends, particularly those
892 that make use of <var>PATH_INFO</var>. The optional <var>nocanon</var>
893 keyword suppresses this, and passes the URL path "raw" to the
894 backend. Note that may affect the security of your backend, as it
895 removes the normal limited protection against URL-based attacks
896 provided by the proxy.</p>
898 <p>The optional <var>interpolate</var> keyword (available in
899 httpd 2.2.9 and later), in combination with
900 <directive>ProxyPassInterpolateEnv</directive> causes the ProxyPass
901 to interpolate environment variables, using the syntax
902 <var>${VARNAME}</var>. Note that many of the standard CGI-derived
903 environment variables will not exist when this interpolation happens,
904 so you may still have to resort to <module>mod_rewrite</module>
905 for complex rules.</p>
907 <p>When used inside a <directive type="section" module="core"
908 >Location</directive> section, the first argument is omitted and the local
909 directory is obtained from the <directive type="section" module="core"
910 >Location</directive>.</p>
912 <p>If you require a more flexible reverse-proxy configuration, see the
913 <directive module="mod_rewrite">RewriteRule</directive> directive with the
914 <code>[P]</code> flag.</p>
919 <name>ProxyPassMatch</name>
920 <description>Maps remote servers into the local server URL-space using regular expressions</description>
921 <syntax>ProxyPassMatch [<var>regex</var>] !|<var>url</var> [<var>key=value</var>
922 <var>[key=value</var> ...]]</syntax>
923 <contextlist><context>server config</context><context>virtual host</context>
924 <context>directory</context>
928 <p>This directive is equivalent to <directive module="mod_proxy">ProxyPass</directive>,
929 but makes use of regular expressions, instead of simple prefix matching. The
930 supplied regular expression is matched against the <var>url</var>, and if it
931 matches, the server will substitute any parenthesized matches into the given
932 string and use it as a new <var>url</var>.</p>
934 <p>Suppose the local server has address <code>http://example.com/</code>;
938 ProxyPassMatch ^(/.*\.gif)$ http://backend.example.com$1
941 <p>will cause a local request for
942 <code>http://example.com/foo/bar.gif</code> to be internally converted
943 into a proxy request to <code>http://backend.example.com/foo/bar.gif</code>.</p>
945 <p>The <code>!</code> directive is useful in situations where you don't want
946 to reverse-proxy a subdirectory.</p>
951 <name>ProxyPassReverse</name>
952 <description>Adjusts the URL in HTTP response headers sent from a reverse
953 proxied server</description>
954 <syntax>ProxyPassReverse [<var>path</var>] <var>url</var>
955 [<var>interpolate</var>]</syntax>
956 <contextlist><context>server config</context><context>virtual host</context>
957 <context>directory</context>
961 <p>This directive lets Apache adjust the URL in the <code>Location</code>,
962 <code>Content-Location</code> and <code>URI</code> headers on HTTP
963 redirect responses. This is essential when Apache is used as a
964 reverse proxy (or gateway) to avoid by-passing the reverse proxy
965 because of HTTP redirects on the backend servers which stay behind
966 the reverse proxy.</p>
968 <p>Only the HTTP response headers specifically mentioned above
969 will be rewritten. Apache will not rewrite other response
970 headers, nor will it rewrite URL references inside HTML pages.
971 This means that if the proxied content contains absolute URL
972 references, they will by-pass the proxy. A third-party module
973 that will look inside the HTML and rewrite URL references is Nick
974 Kew's <a href="http://apache.webthing.com/mod_proxy_html/"
975 >mod_proxy_html</a>.</p>
977 <p><var>path</var> is the name of a local virtual path. <var>url</var> is a
978 partial URL for the remote server - the same way they are used for the
979 <directive module="mod_proxy">ProxyPass</directive> directive.</p>
981 <p>For example, suppose the local server has address
982 <code>http://example.com/</code>; then</p>
985 ProxyPass /mirror/foo/ http://backend.example.com/<br />
986 ProxyPassReverse /mirror/foo/ http://backend.example.com/<br />
987 ProxyPassReverseCookieDomain backend.example.com public.example.com<br />
988 ProxyPassReverseCookiePath / /mirror/foo/
991 <p>will not only cause a local request for the
992 <code>http://example.com/mirror/foo/bar</code> to be internally converted
993 into a proxy request to <code>http://backend.example.com/bar</code>
994 (the functionality <code>ProxyPass</code> provides here). It also takes care
995 of redirects the server <code>backend.example.com</code> sends: when
996 <code>http://backend.example.com/bar</code> is redirected by him to
997 <code>http://backend.example.com/quux</code> Apache adjusts this to
998 <code>http://example.com/mirror/foo/quux</code> before forwarding the HTTP
999 redirect response to the client. Note that the hostname used for
1000 constructing the URL is chosen in respect to the setting of the <directive
1001 module="core">UseCanonicalName</directive> directive.</p>
1003 <p>Note that this <directive>ProxyPassReverse</directive> directive can
1004 also be used in conjunction with the proxy pass-through feature
1005 (<code>RewriteRule ... [P]</code>) from <module>mod_rewrite</module>
1006 because it doesn't depend on a corresponding <directive module="mod_proxy"
1007 >ProxyPass</directive> directive.</p>
1009 <p>The optional <var>interpolate</var> keyword (available in
1010 httpd 2.2.9 and later), used together with
1011 <directive>ProxyPassInterpolateEnv</directive>, enables interpolation
1012 of environment variables specified using the format <var>${VARNAME}</var>.
1015 <p>When used inside a <directive type="section" module="core"
1016 >Location</directive> section, the first argument is omitted and the local
1017 directory is obtained from the <directive type="section" module="core"
1018 >Location</directive>.</p>
1020 </directivesynopsis>
1023 <name>ProxyPassReverseCookieDomain</name>
1024 <description>Adjusts the Domain string in Set-Cookie headers from a reverse-
1025 proxied server</description>
1026 <syntax>ProxyPassReverseCookieDomain <var>internal-domain</var>
1027 <var>public-domain</var> [<var>interpolate</var>]</syntax>
1028 <contextlist><context>server config</context><context>virtual host</context>
1029 <context>directory</context>
1032 <p>Usage is basically similar to
1033 <directive module="mod_proxy">ProxyPassReverse</directive>, but instead of
1034 rewriting headers that are a URL, this rewrites the <code>domain</code>
1035 string in <code>Set-Cookie</code> headers.</p>
1037 </directivesynopsis>
1039 <name>ProxyPassReverseCookiePath</name>
1040 <description>Adjusts the Path string in Set-Cookie headers from a reverse-
1041 proxied server</description>
1042 <syntax>ProxyPassReverseCookiePath <var>internal-path</var>
1043 <var>public-path</var> [<var>interpolate</var>]</syntax>
1044 <contextlist><context>server config</context><context>virtual host</context>
1045 <context>directory</context>
1048 <p>Usage is basically similar to
1049 <directive module="mod_proxy">ProxyPassReverse</directive>, but instead of
1050 rewriting headers that are a URL, this rewrites the <code>path</code>
1051 string in <code>Set-Cookie</code> headers.</p>
1053 </directivesynopsis>
1057 <name>AllowCONNECT</name>
1058 <description>Ports that are allowed to <code>CONNECT</code> through the
1060 <syntax>AllowCONNECT <var>port</var> [<var>port</var>] ...</syntax>
1061 <default>AllowCONNECT 443 563</default>
1062 <contextlist><context>server config</context><context>virtual host</context>
1066 <p>The <directive>AllowCONNECT</directive> directive specifies a list
1067 of port numbers to which the proxy <code>CONNECT</code> method may
1068 connect. Today's browsers use this method when a <code>https</code>
1069 connection is requested and proxy tunneling over HTTP is in effect.</p>
1071 <p>By default, only the default https port (<code>443</code>) and the
1072 default snews port (<code>563</code>) are enabled. Use the
1073 <directive>AllowCONNECT</directive> directive to override this default and
1074 allow connections to the listed ports only.</p>
1076 <p>Note that you'll need to have <module>mod_proxy_connect</module> present
1077 in the server in order to get the support for the <code>CONNECT</code> at
1080 </directivesynopsis>
1083 <name>ProxyBlock</name>
1084 <description>Words, hosts, or domains that are banned from being
1085 proxied</description>
1086 <syntax>ProxyBlock *|<var>word</var>|<var>host</var>|<var>domain</var>
1087 [<var>word</var>|<var>host</var>|<var>domain</var>] ...</syntax>
1088 <contextlist><context>server config</context><context>virtual host</context>
1092 <p>The <directive>ProxyBlock</directive> directive specifies a list of
1093 words, hosts and/or domains, separated by spaces. HTTP, HTTPS, and
1094 FTP document requests to sites whose names contain matched words,
1095 hosts or domains are <em>blocked</em> by the proxy server. The proxy
1096 module will also attempt to determine IP addresses of list items which
1097 may be hostnames during startup, and cache them for match test as
1098 well. That may slow down the startup time of the server.</p>
1100 <example><title>Example</title>
1101 ProxyBlock joes-garage.com some-host.co.uk rocky.wotsamattau.edu
1104 <p><code>rocky.wotsamattau.edu</code> would also be matched if referenced by
1107 <p>Note that <code>wotsamattau</code> would also be sufficient to match
1108 <code>wotsamattau.edu</code>.</p>
1110 <p>Note also that</p>
1116 <p>blocks connections to all sites.</p>
1118 </directivesynopsis>
1121 <name>ProxyReceiveBufferSize</name>
1122 <description>Network buffer size for proxied HTTP and FTP
1123 connections</description>
1124 <syntax>ProxyReceiveBufferSize <var>bytes</var></syntax>
1125 <default>ProxyReceiveBufferSize 0</default>
1126 <contextlist><context>server config</context><context>virtual host</context>
1130 <p>The <directive>ProxyReceiveBufferSize</directive> directive specifies an
1131 explicit (TCP/IP) network buffer size for proxied HTTP and FTP connections,
1132 for increased throughput. It has to be greater than <code>512</code> or set
1133 to <code>0</code> to indicate that the system's default buffer size should
1136 <example><title>Example</title>
1137 ProxyReceiveBufferSize 2048
1140 </directivesynopsis>
1143 <name>ProxyIOBufferSize</name>
1144 <description>Determine size of internal data throughput buffer</description>
1145 <syntax>ProxyIOBufferSize <var>bytes</var></syntax>
1146 <default>ProxyIOBufferSize 8192</default>
1147 <contextlist><context>server config</context><context>virtual host</context>
1151 <p>The <directive>ProxyIOBufferSize</directive> directive adjusts the size
1152 of the internal buffer, which is used as a scratchpad for the data between
1153 input and output. The size must be less or equal <code>65536</code>.</p>
1155 <p>In almost every case there's no reason to change that value.</p>
1156 <p>If used with AJP this directive sets the maximum AJP packet size in
1157 bytes. If you change it from the default, you must also change the
1158 <code>packetSize</code> attribute of your AJP connector on the
1159 Tomcat side! The attribute <code>packetSize</code> is only available
1160 in Tomcat <code>5.5.20+</code> and <code>6.0.2+</code></p>
1161 <p>Normally it is not necessary to change the maximum packet size.
1162 Problems with the default value have been reported when sending
1163 certificates or certificate chains.</p>
1166 </directivesynopsis>
1169 <name>ProxyMaxForwards</name>
1170 <description>Maximium number of proxies that a request can be forwarded
1171 through</description>
1172 <syntax>ProxyMaxForwards <var>number</var></syntax>
1173 <default>ProxyMaxForwards -1</default>
1174 <contextlist><context>server config</context><context>virtual host</context>
1176 <compatibility>Available in Apache 2.0 and later;
1177 default behaviour changed in 2.2.7/2.3</compatibility>
1180 <p>The <directive>ProxyMaxForwards</directive> directive specifies the
1181 maximum number of proxies through which a request may pass, if there's no
1182 <code>Max-Forwards</code> header supplied with the request. This may
1183 be set to prevent infinite proxy loops, or a DoS attack.</p>
1185 <example><title>Example</title>
1189 <p>Note that setting <directive>ProxyMaxForwards</directive> is a
1190 violation of the HTTP/1.1 protocol (RFC2616), which forbids a Proxy
1191 setting <code>Max-Forwards</code> if the Client didn't set it.
1192 Earlier Apache versions would always set it. A negative
1193 <directive>ProxyMaxForwards</directive> value, including the
1194 default -1, gives you protocol-compliant behaviour, but may
1195 leave you open to loops.</p>
1197 </directivesynopsis>
1200 <name>NoProxy</name>
1201 <description>Hosts, domains, or networks that will be connected to
1202 directly</description>
1203 <syntax>NoProxy <var>host</var> [<var>host</var>] ...</syntax>
1204 <contextlist><context>server config</context><context>virtual host</context>
1208 <p>This directive is only useful for Apache proxy servers within
1209 intranets. The <directive>NoProxy</directive> directive specifies a
1210 list of subnets, IP addresses, hosts and/or domains, separated by
1211 spaces. A request to a host which matches one or more of these is
1212 always served directly, without forwarding to the configured
1213 <directive module="mod_proxy">ProxyRemote</directive> proxy server(s).</p>
1215 <example><title>Example</title>
1216 ProxyRemote * http://firewall.example.com:81<br />
1217 NoProxy .example.com 192.168.112.0/21
1220 <p>The <var>host</var> arguments to the <directive>NoProxy</directive>
1221 directive are one of the following type list:</p>
1224 <!-- ===================== Domain ======================= -->
1225 <dt><var><a name="domain" id="domain">Domain</a></var></dt>
1227 <p>A <dfn>Domain</dfn> is a partially qualified DNS domain name, preceded
1228 by a period. It represents a list of hosts which logically belong to the
1229 same DNS domain or zone (<em>i.e.</em>, the suffixes of the hostnames are
1230 all ending in <var>Domain</var>).</p>
1232 <example><title>Examples</title>
1236 <p>To distinguish <var>Domain</var>s from <var><a href="#hostname"
1237 >Hostname</a></var>s (both syntactically and semantically; a DNS domain can
1238 have a DNS A record, too!), <var>Domain</var>s are always written with a
1241 <note><title>Note</title>
1242 <p>Domain name comparisons are done without regard to the case, and
1243 <var>Domain</var>s are always assumed to be anchored in the root of the
1244 DNS tree, therefore two domains <code>.ExAmple.com</code> and
1245 <code>.example.com.</code> (note the trailing period) are considered
1246 equal. Since a domain comparison does not involve a DNS lookup, it is much
1247 more efficient than subnet comparison.</p>
1250 <!-- ===================== SubNet ======================= -->
1251 <dt><var><a name="subnet" id="subnet">SubNet</a></var></dt>
1253 <p>A <dfn>SubNet</dfn> is a partially qualified internet address in
1254 numeric (dotted quad) form, optionally followed by a slash and the netmask,
1255 specified as the number of significant bits in the <var>SubNet</var>. It is
1256 used to represent a subnet of hosts which can be reached over a common
1257 network interface. In the absence of the explicit net mask it is assumed
1258 that omitted (or zero valued) trailing digits specify the mask. (In this
1259 case, the netmask can only be multiples of 8 bits wide.) Examples:</p>
1262 <dt><code>192.168</code> or <code>192.168.0.0</code></dt>
1263 <dd>the subnet 192.168.0.0 with an implied netmask of 16 valid bits
1264 (sometimes used in the netmask form <code>255.255.0.0</code>)</dd>
1265 <dt><code>192.168.112.0/21</code></dt>
1266 <dd>the subnet <code>192.168.112.0/21</code> with a netmask of 21
1267 valid bits (also used in the form <code>255.255.248.0</code>)</dd>
1270 <p>As a degenerate case, a <em>SubNet</em> with 32 valid bits is the
1271 equivalent to an <var><a href="#ipadr">IPAddr</a></var>, while a <var>SubNet</var> with zero
1272 valid bits (<em>e.g.</em>, 0.0.0.0/0) is the same as the constant
1273 <var>_Default_</var>, matching any IP address.</p></dd>
1275 <!-- ===================== IPAddr ======================= -->
1276 <dt><var><a name="ipaddr" id="ipaddr">IPAddr</a></var></dt>
1278 <p>A <dfn>IPAddr</dfn> represents a fully qualified internet address in
1279 numeric (dotted quad) form. Usually, this address represents a host, but
1280 there need not necessarily be a DNS domain name connected with the
1282 <example><title>Example</title>
1286 <note><title>Note</title>
1287 <p>An <var>IPAddr</var> does not need to be resolved by the DNS system, so
1288 it can result in more effective apache performance.</p>
1291 <!-- ===================== Hostname ======================= -->
1292 <dt><var><a name="hostname" id="hostname">Hostname</a></var></dt>
1294 <p>A <dfn>Hostname</dfn> is a fully qualified DNS domain name which can
1295 be resolved to one or more <var><a href="#ipaddr">IPAddrs</a></var> via the
1296 DNS domain name service. It represents a logical host (in contrast to
1297 <var><a href="#domain">Domain</a></var>s, see above) and must be resolvable
1298 to at least one <var><a href="#ipaddr">IPAddr</a></var> (or often to a list
1299 of hosts with different <var><a href="#ipaddr">IPAddr</a></var>s).</p>
1301 <example><title>Examples</title>
1302 prep.ai.example.com<br />
1306 <note><title>Note</title>
1307 <p>In many situations, it is more effective to specify an <var><a
1308 href="#ipaddr">IPAddr</a></var> in place of a <var>Hostname</var> since a
1309 DNS lookup can be avoided. Name resolution in Apache can take a remarkable
1310 deal of time when the connection to the name server uses a slow PPP
1312 <p><var>Hostname</var> comparisons are done without regard to the case,
1313 and <var>Hostname</var>s are always assumed to be anchored in the root
1314 of the DNS tree, therefore two hosts <code>WWW.ExAmple.com</code>
1315 and <code>www.example.com.</code> (note the trailing period) are
1316 considered equal.</p>
1320 <seealso><a href="../dns-caveats.html">DNS Issues</a></seealso>
1321 </directivesynopsis>
1324 <name>ProxyTimeout</name>
1325 <description>Network timeout for proxied requests</description>
1326 <syntax>ProxyTimeout <var>seconds</var></syntax>
1327 <default>Value of <directive module="core">Timeout</directive></default>
1328 <contextlist><context>server config</context><context>virtual host</context>
1330 <compatibility>Available in Apache 2.0.31 and later</compatibility>
1333 <p>This directive allows a user to specifiy a timeout on proxy requests.
1334 This is useful when you have a slow/buggy appserver which hangs, and you
1335 would rather just return a timeout and fail gracefully instead of waiting
1336 however long it takes the server to return.</p>
1338 </directivesynopsis>
1341 <name>ProxyDomain</name>
1342 <description>Default domain name for proxied requests</description>
1343 <syntax>ProxyDomain <var>Domain</var></syntax>
1344 <contextlist><context>server config</context><context>virtual host</context>
1348 <p>This directive is only useful for Apache proxy servers within
1349 intranets. The <directive>ProxyDomain</directive> directive specifies
1350 the default domain which the apache proxy server will belong to. If a
1351 request to a host without a domain name is encountered, a redirection
1352 response to the same host with the configured <var>Domain</var> appended
1353 will be generated.</p>
1355 <example><title>Example</title>
1356 ProxyRemote * http://firewall.example.com:81<br />
1357 NoProxy .example.com 192.168.112.0/21<br />
1358 ProxyDomain .example.com
1361 </directivesynopsis>
1364 <name>ProxyVia</name>
1365 <description>Information provided in the <code>Via</code> HTTP response
1366 header for proxied requests</description>
1367 <syntax>ProxyVia On|Off|Full|Block</syntax>
1368 <default>ProxyVia Off</default>
1369 <contextlist><context>server config</context><context>virtual host</context>
1373 <p>This directive controls the use of the <code>Via:</code> HTTP
1374 header by the proxy. Its intended use is to control the flow of
1375 proxy requests along a chain of proxy servers. See <a
1376 href="http://www.ietf.org/rfc/rfc2616.txt">RFC 2616</a> (HTTP/1.1), section
1377 14.45 for an explanation of <code>Via:</code> header lines.</p>
1380 <li>If set to <code>Off</code>, which is the default, no special processing
1381 is performed. If a request or reply contains a <code>Via:</code> header,
1382 it is passed through unchanged.</li>
1384 <li>If set to <code>On</code>, each request and reply will get a
1385 <code>Via:</code> header line added for the current host.</li>
1387 <li>If set to <code>Full</code>, each generated <code>Via:</code> header
1388 line will additionally have the Apache server version shown as a
1389 <code>Via:</code> comment field.</li>
1391 <li>If set to <code>Block</code>, every proxy request will have all its
1392 <code>Via:</code> header lines removed. No new <code>Via:</code> header will
1396 </directivesynopsis>
1399 <name>ProxyErrorOverride</name>
1400 <description>Override error pages for proxied content</description>
1401 <syntax>ProxyErrorOverride On|Off</syntax>
1402 <default>ProxyErrorOverride Off</default>
1403 <contextlist><context>server config</context><context>virtual host</context>
1405 <compatibility>Available in version 2.0 and later</compatibility>
1408 <p>This directive is useful for reverse-proxy setups, where you want to
1409 have a common look and feel on the error pages seen by the end user.
1410 This also allows for included files (via
1411 <module>mod_include</module>'s SSI) to get
1412 the error code and act accordingly (default behavior would display
1413 the error page of the proxied server, turning this on shows the SSI
1416 <p>This directive does not affect the processing of informational (1xx),
1417 normal success (2xx), or redirect (3xx) responses.</p>
1419 </directivesynopsis>
1422 <name>ProxyPassInterpolateEnv</name>
1423 <description>Enable Environment Variable interpolation in Reverse Proxy configurations</description>
1424 <syntax>ProxyPassInterpolateEnv On|Off</syntax>
1425 <default>ProxyPassInterpolateEnv Off</default>
1426 <contextlist><context>server config</context>
1427 <context>virtual host</context>
1428 <context>directory</context>
1430 <compatibility>Available in httpd 2.2.9 and later</compatibility>
1433 <p>This directive, together with the <var>interpolate</var> argument to
1434 <directive>ProxyPass</directive>, <directive>ProxyPassReverse</directive>,
1435 <directive>ProxyPassReverseCookieDomain</directive> and
1436 <directive>ProxyPassReverseCookiePath</directive>
1437 enables reverse proxies to be dynamically
1438 configured using environment variables, which may be set by
1439 another module such as <module>mod_rewrite</module>.
1440 It affects the <directive>ProxyPass</directive>,
1441 <directive>ProxyPassReverse</directive>,
1442 <directive>ProxyPassReverseCookieDomain</directive>, and
1443 <directive>ProxyPassReverseCookiePath</directive> directives,
1444 and causes them to substitute the value of an environment
1445 variable <code>varname</code> for the string <code>${varname}</code>
1446 in configuration directives.</p>
1447 <p>Keep this turned off (for server performance) unless you need it!</p>
1449 </directivesynopsis>
1452 <name>ProxyStatus</name>
1453 <description>Show Proxy LoadBalancer status in mod_status</description>
1454 <syntax>ProxyStatus Off|On|Full</syntax>
1455 <default>ProxyStatus Off</default>
1456 <contextlist><context>server config</context>
1457 <context>virtual host</context>
1459 <compatibility>Available in version 2.2 and later</compatibility>
1462 <p>This directive determines whether or not proxy
1463 loadbalancer status data is displayed via the <module>mod_status</module>
1464 server-status page.</p>
1465 <note><title>Note</title>
1466 <p><strong>Full</strong> is synonymous with <strong>On</strong></p>
1470 </directivesynopsis>