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19 <p class="apache">Apache HTTP Server Version 2.5</p>
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24 <div id="page-content">
25 <div id="preamble"><h1>Apache Module mod_proxy</h1>
27 <p><span>Available Languages: </span><a href="../en/mod/mod_proxy.html" title="English"> en </a> |
28 <a href="../fr/mod/mod_proxy.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
29 <a href="../ja/mod/mod_proxy.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
31 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Multi-protocol proxy/gateway server</td></tr>
32 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
33 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>proxy_module</td></tr>
34 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_proxy.c</td></tr></table>
37 <div class="warning"><h3>Warning</h3>
38 <p>Do not enable proxying with <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> until you have <a href="#access">secured your server</a>. Open proxy servers are dangerous both to your
39 network and to the Internet at large.</p>
42 <p><code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> and related modules implement a
43 proxy/gateway for Apache HTTP Server, supporting a number of popular
44 protocols as well as several different load balancing algorithms.
45 Third-party modules can add support for additional protocols and
46 load balancing algorithms.</p>
48 <p>A set of modules must be loaded into the server to provide the
49 necessary features. These modules can be included statically at
50 build time or dynamically via the
51 <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code> directive).
52 The set must include:</p>
55 <li><code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, which provides basic proxy
58 <li><code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code> and one or more
59 balancer modules, if load balancing is required. (See
60 <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code> for more information.)</li>
62 <li>one or more proxy scheme, or protocol, modules:
64 <table class="bordered">
65 <tr><th>Protocol</th><th>Module</th></tr>
66 <tr><td>AJP13 (Apache JServe Protocol version
67 1.3)</td><td><code class="module"><a href="../mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code></td></tr>
69 SSL)</td><td><code class="module"><a href="../mod/mod_proxy_connect.html">mod_proxy_connect</a></code></td></tr>
70 <tr><td>FastCGI</td><td><code class="module"><a href="../mod/mod_proxy_fcgi.html">mod_proxy_fcgi</a></code></td></tr>
71 <tr><td>ftp</td><td><code class="module"><a href="../mod/mod_proxy_ftp.html">mod_proxy_ftp</a></code></td></tr>
72 <tr><td>HTTP/0.9, HTTP/1.0, and
73 HTTP/1.1</td><td><code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code></td></tr>
74 <tr><td>SCGI</td><td><code class="module"><a href="../mod/mod_proxy_scgi.html">mod_proxy_scgi</a></code></td></tr>
79 <p>In addition, extended features are provided by other modules.
80 Caching is provided by <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> and related
81 modules. The ability to contact remote servers using the SSL/TLS
82 protocol is provided by the <code>SSLProxy*</code> directives of
83 <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code>. These additional modules will need
84 to be loaded and configured to take advantage of these features.</p>
86 <div id="quickview"><h3 class="directives">Directives</h3>
88 <li><img alt="" src="../images/down.gif" /> <a href="#balancergrowth">BalancerGrowth</a></li>
89 <li><img alt="" src="../images/down.gif" /> <a href="#balancermember">BalancerMember</a></li>
90 <li><img alt="" src="../images/down.gif" /> <a href="#noproxy">NoProxy</a></li>
91 <li><img alt="" src="../images/down.gif" /> <a href="#proxy"><Proxy></a></li>
92 <li><img alt="" src="../images/down.gif" /> <a href="#proxyaddheaders">ProxyAddHeaders</a></li>
93 <li><img alt="" src="../images/down.gif" /> <a href="#proxybadheader">ProxyBadHeader</a></li>
94 <li><img alt="" src="../images/down.gif" /> <a href="#proxyblock">ProxyBlock</a></li>
95 <li><img alt="" src="../images/down.gif" /> <a href="#proxydomain">ProxyDomain</a></li>
96 <li><img alt="" src="../images/down.gif" /> <a href="#proxyerroroverride">ProxyErrorOverride</a></li>
97 <li><img alt="" src="../images/down.gif" /> <a href="#proxyiobuffersize">ProxyIOBufferSize</a></li>
98 <li><img alt="" src="../images/down.gif" /> <a href="#proxymatch"><ProxyMatch></a></li>
99 <li><img alt="" src="../images/down.gif" /> <a href="#proxymaxforwards">ProxyMaxForwards</a></li>
100 <li><img alt="" src="../images/down.gif" /> <a href="#proxypass">ProxyPass</a></li>
101 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassinterpolateenv">ProxyPassInterpolateEnv</a></li>
102 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassmatch">ProxyPassMatch</a></li>
103 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassreverse">ProxyPassReverse</a></li>
104 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassreversecookiedomain">ProxyPassReverseCookieDomain</a></li>
105 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassreversecookiepath">ProxyPassReverseCookiePath</a></li>
106 <li><img alt="" src="../images/down.gif" /> <a href="#proxypreservehost">ProxyPreserveHost</a></li>
107 <li><img alt="" src="../images/down.gif" /> <a href="#proxyreceivebuffersize">ProxyReceiveBufferSize</a></li>
108 <li><img alt="" src="../images/down.gif" /> <a href="#proxyremote">ProxyRemote</a></li>
109 <li><img alt="" src="../images/down.gif" /> <a href="#proxyremotematch">ProxyRemoteMatch</a></li>
110 <li><img alt="" src="../images/down.gif" /> <a href="#proxyrequests">ProxyRequests</a></li>
111 <li><img alt="" src="../images/down.gif" /> <a href="#proxyset">ProxySet</a></li>
112 <li><img alt="" src="../images/down.gif" /> <a href="#proxysourceaddress">ProxySourceAddress</a></li>
113 <li><img alt="" src="../images/down.gif" /> <a href="#proxystatus">ProxyStatus</a></li>
114 <li><img alt="" src="../images/down.gif" /> <a href="#proxytimeout">ProxyTimeout</a></li>
115 <li><img alt="" src="../images/down.gif" /> <a href="#proxyvia">ProxyVia</a></li>
119 <li><img alt="" src="../images/down.gif" /> <a href="#forwardreverse">Forward Proxies and Reverse
120 Proxies/Gateways</a></li>
121 <li><img alt="" src="../images/down.gif" /> <a href="#examples">Basic Examples</a></li>
122 <li><img alt="" src="../images/down.gif" /> <a href="#workers">Workers</a></li>
123 <li><img alt="" src="../images/down.gif" /> <a href="#access">Controlling access to your proxy</a></li>
124 <li><img alt="" src="../images/down.gif" /> <a href="#startup">Slow Startup</a></li>
125 <li><img alt="" src="../images/down.gif" /> <a href="#intranet">Intranet Proxy</a></li>
126 <li><img alt="" src="../images/down.gif" /> <a href="#envsettings">Protocol Adjustments</a></li>
127 <li><img alt="" src="../images/down.gif" /> <a href="#request-bodies">Request Bodies</a></li>
128 <li><img alt="" src="../images/down.gif" /> <a href="#x-headers">Reverse Proxy Request Headers</a></li>
129 </ul><h3>See also</h3>
131 <li><code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code></li>
132 <li><code class="module"><a href="../mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code></li>
133 <li><code class="module"><a href="../mod/mod_proxy_connect.html">mod_proxy_connect</a></code></li>
134 <li><code class="module"><a href="../mod/mod_proxy_fcgi.html">mod_proxy_fcgi</a></code></li>
135 <li><code class="module"><a href="../mod/mod_proxy_ftp.html">mod_proxy_ftp</a></code></li>
136 <li><code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code></li>
137 <li><code class="module"><a href="../mod/mod_proxy_scgi.html">mod_proxy_scgi</a></code></li>
138 <li><code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code></li>
139 <li><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></li>
141 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
142 <div class="section">
143 <h2><a name="forwardreverse" id="forwardreverse">Forward Proxies and Reverse
144 Proxies/Gateways</a></h2>
145 <p>Apache HTTP Server can be configured in both a <dfn>forward</dfn> and
146 <dfn>reverse</dfn> proxy (also known as <dfn>gateway</dfn>) mode.</p>
148 <p>An ordinary <dfn>forward proxy</dfn> is an intermediate
149 server that sits between the client and the <em>origin
150 server</em>. In order to get content from the origin server,
151 the client sends a request to the proxy naming the origin server
152 as the target and the proxy then requests the content from the
153 origin server and returns it to the client. The client must be
154 specially configured to use the forward proxy to access other
157 <p>A typical usage of a forward proxy is to provide Internet
158 access to internal clients that are otherwise restricted by a
159 firewall. The forward proxy can also use caching (as provided
160 by <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code>) to reduce network usage.</p>
162 <p>The forward proxy is activated using the <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> directive. Because
163 forward proxies allow clients to access arbitrary sites through
164 your server and to hide their true origin, it is essential that
165 you <a href="#access">secure your server</a> so that only
166 authorized clients can access the proxy before activating a
169 <p>A <dfn>reverse proxy</dfn> (or <dfn>gateway</dfn>), by
170 contrast, appears to the client just like an ordinary web
171 server. No special configuration on the client is necessary.
172 The client makes ordinary requests for content in the name-space
173 of the reverse proxy. The reverse proxy then decides where to
174 send those requests, and returns the content as if it was itself
177 <p>A typical usage of a reverse proxy is to provide Internet
178 users access to a server that is behind a firewall. Reverse
179 proxies can also be used to balance load among several back-end
180 servers, or to provide caching for a slower back-end server.
181 In addition, reverse proxies can be used simply to bring
182 several servers into the same URL space.</p>
184 <p>A reverse proxy is activated using the <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive or the
185 <code>[P]</code> flag to the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directive. It is
186 <strong>not</strong> necessary to turn <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> on in order to
187 configure a reverse proxy.</p>
188 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
189 <div class="section">
190 <h2><a name="examples" id="examples">Basic Examples</a></h2>
192 <p>The examples below are only a very basic idea to help you
193 get started. Please read the documentation on the individual
196 <p>In addition, if you wish to have caching enabled, consult
197 the documentation from <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code>.</p>
199 <div class="example"><h3>Reverse Proxy</h3><pre class="prettyprint lang-config">
200 ProxyPass /foo http://foo.example.com/bar
201 ProxyPassReverse /foo http://foo.example.com/bar
205 <div class="example"><h3>Forward Proxy</h3><pre class="prettyprint lang-config">
210 Require host internal.example.com
214 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
215 <div class="section">
216 <h2><a name="workers" id="workers">Workers</a></h2>
217 <p>The proxy manages the configuration of origin servers and their
218 communication parameters in objects called <dfn>workers</dfn>.
219 There are two built-in workers, the default forward proxy worker and the
220 default reverse proxy worker. Additional workers can be configured
223 <p>The two default workers have a fixed configuration
224 and will be used if no other worker matches the request.
225 They do not use HTTP Keep-Alive or connection pooling.
226 The TCP connections to the origin server will instead be
227 opened and closed for each request.</p>
229 <p>Explicitly configured workers are identified by their URL.
230 They are usually created and configured using
231 <code class="directive"><a href="#proxypass">ProxyPass</a></code> or
232 <code class="directive"><a href="#proxypassmatch">ProxyPassMatch</a></code> when used
233 for a reverse proxy:</p>
235 <pre class="prettyprint lang-config">
236 ProxyPass /example http://backend.example.com connectiontimeout=5 timeout=30
240 <p>This will create a worker associated with the origin server URL
241 <code>http://backend.example.com</code> and using the given timeout
242 values. When used in a forward proxy, workers are usually defined
243 via the <code class="directive"><a href="#proxyset">ProxySet</a></code> directive:</p>
245 <pre class="prettyprint lang-config">
246 ProxySet http://backend.example.com connectiontimeout=5 timeout=30
250 <p>or alternatively using <code class="directive"><a href="#proxy">Proxy</a></code>
251 and <code class="directive"><a href="#proxyset">ProxySet</a></code>:</p>
253 <pre class="prettyprint lang-config">
254 <Proxy http://backend.example.com>
255 ProxySet connectiontimeout=5 timeout=30
260 <p>Using explicitly configured workers in the forward mode is
261 not very common, because forward proxies usually communicate with many
262 different origin servers. Creating explicit workers for some of the
263 origin servers can still be useful, if they are used very often.
264 Explicitly configured workers have no concept of forward or reverse
265 proxying by themselves. They encapsulate a common concept of
266 communication with origin servers. A worker created by
267 <code class="directive"><a href="#proxypass">ProxyPass</a></code> for use in a
268 reverse proxy will be also used for forward proxy requests whenever
269 the URL to the origin server matches the worker URL and vice versa.</p>
271 <p>The URL identifying a direct worker is the URL of its
272 origin server including any path components given:</p>
274 <pre class="prettyprint lang-config">
275 ProxyPass /examples http://backend.example.com/examples
276 ProxyPass /docs http://backend.example.com/docs
280 <p>This example defines two different workers, each using a separate
281 connection pool and configuration.</p>
283 <div class="warning"><h3>Worker Sharing</h3>
284 <p>Worker sharing happens if the worker URLs overlap, which occurs when
285 the URL of some worker is a leading substring of the URL of another
286 worker defined later in the configuration file. In the following example</p>
288 <pre class="prettyprint lang-config">
289 ProxyPass /apps http://backend.example.com/ timeout=60
290 ProxyPass /examples http://backend.example.com/examples timeout=10
294 <p>the second worker isn't actually created. Instead the first
295 worker is used. The benefit is, that there is only one connection pool,
296 so connections are more often reused. Note that all configuration attributes
297 given explicitly for the later worker will be ignored. This will be logged
298 as a warning. In the above example the resulting timeout value
299 for the URL <code>/examples</code> will be <code>60</code> instead
300 of <code>10</code>!</p>
302 <p>If you want to avoid worker sharing, sort your worker definitions
303 by URL length, starting with the longest worker URLs. If you want to maximize
304 worker sharing use the reverse sort order. See also the related warning about
305 ordering <code class="directive"><a href="#proxypass">ProxyPass</a></code> directives.</p>
309 <p>Explicitly configured workers come in two flavors:
310 <dfn>direct workers</dfn> and <dfn>(load) balancer workers</dfn>.
311 They support many important configuration attributes which are
312 described below in the <code class="directive"><a href="#proxypass">ProxyPass</a></code>
313 directive. The same attributes can also be set using
314 <code class="directive"><a href="#proxyset">ProxySet</a></code>.</p>
316 <p>The set of options available for a direct worker
317 depends on the protocol, which is specified in the origin server URL.
318 Available protocols include <code>ajp</code>, <code>fcgi</code>,
319 <code>ftp</code>, <code>http</code> and <code>scgi</code>.</p>
321 <p>Balancer workers are virtual workers that use direct workers known
322 as their members to actually handle the requests. Each balancer can
323 have multiple members. When it handles a request, it chooses a member
324 based on the configured load balancing algorithm.</p>
326 <p>A balancer worker is created if its worker URL uses
327 <code>balancer</code> as the protocol scheme.
328 The balancer URL uniquely identifies the balancer worker.
329 Members are added to a balancer using
330 <code class="directive"><a href="#balancermember">BalancerMember</a></code>.</p>
332 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
333 <div class="section">
334 <h2><a name="access" id="access">Controlling access to your proxy</a></h2>
335 <p>You can control who can access your proxy via the <code class="directive"><a href="#proxy"><Proxy></a></code> control block as in
336 the following example:</p>
338 <pre class="prettyprint lang-config">
345 <p>For more information on access control directives, see
346 <code class="module"><a href="../mod/mod_authz_host.html">mod_authz_host</a></code>.</p>
348 <p>Strictly limiting access is essential if you are using a
349 forward proxy (using the <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> directive).
350 Otherwise, your server can be used by any client to access
351 arbitrary hosts while hiding his or her true identity. This is
352 dangerous both for your network and for the Internet at large.
353 When using a reverse proxy (using the <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive with
354 <code>ProxyRequests Off</code>), access control is less
355 critical because clients can only contact the hosts that you
356 have specifically configured.</p>
358 <p><strong>See Also</strong> the <a href="mod_proxy_http.html#env">Proxy-Chain-Auth</a> environment variable.</p>
360 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
361 <div class="section">
362 <h2><a name="startup" id="startup">Slow Startup</a></h2>
363 <p>If you're using the <code class="directive"><a href="#proxyblock">ProxyBlock</a></code> directive, hostnames' IP addresses are looked up
364 and cached during startup for later match test. This may take a few
365 seconds (or more) depending on the speed with which the hostname lookups
367 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
368 <div class="section">
369 <h2><a name="intranet" id="intranet">Intranet Proxy</a></h2>
370 <p>An Apache httpd proxy server situated in an intranet needs to forward
371 external requests through the company's firewall (for this, configure
372 the <code class="directive"><a href="#proxyremote">ProxyRemote</a></code> directive
373 to forward the respective <var>scheme</var> to the firewall proxy).
374 However, when it has to
375 access resources within the intranet, it can bypass the firewall when
376 accessing hosts. The <code class="directive"><a href="#noproxy">NoProxy</a></code>
377 directive is useful for specifying which hosts belong to the intranet and
378 should be accessed directly.</p>
380 <p>Users within an intranet tend to omit the local domain name from their
381 WWW requests, thus requesting "http://somehost/" instead of
382 <code>http://somehost.example.com/</code>. Some commercial proxy servers
383 let them get away with this and simply serve the request, implying a
384 configured local domain. When the <code class="directive"><a href="#proxydomain">ProxyDomain</a></code> directive is used and the server is <a href="#proxyrequests">configured for proxy service</a>, Apache httpd can return
385 a redirect response and send the client to the correct, fully qualified,
386 server address. This is the preferred method since the user's bookmark
387 files will then contain fully qualified hosts.</p>
388 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
389 <div class="section">
390 <h2><a name="envsettings" id="envsettings">Protocol Adjustments</a></h2>
391 <p>For circumstances where <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> is sending
392 requests to an origin server that doesn't properly implement
393 keepalives or HTTP/1.1, there are two <a href="../env.html">environment variables</a> that can force the
394 request to use HTTP/1.0 with no keepalive. These are set via the
395 <code class="directive"><a href="../mod/mod_env.html#setenv">SetEnv</a></code> directive.</p>
397 <p>These are the <code>force-proxy-request-1.0</code> and
398 <code>proxy-nokeepalive</code> notes.</p>
400 <pre class="prettyprint lang-config">
401 <Location /buggyappserver/>
402 ProxyPass http://buggyappserver:7001/foo/
403 SetEnv force-proxy-request-1.0 1
404 SetEnv proxy-nokeepalive 1
409 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
410 <div class="section">
411 <h2><a name="request-bodies" id="request-bodies">Request Bodies</a></h2>
413 <p>Some request methods such as POST include a request body.
414 The HTTP protocol requires that requests which include a body
415 either use chunked transfer encoding or send a
416 <code>Content-Length</code> request header. When passing these
417 requests on to the origin server, <code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code>
418 will always attempt to send the <code>Content-Length</code>. But
419 if the body is large and the original request used chunked
420 encoding, then chunked encoding may also be used in the upstream
421 request. You can control this selection using <a href="../env.html">environment variables</a>. Setting
422 <code>proxy-sendcl</code> ensures maximum compatibility with
423 upstream servers by always sending the
424 <code>Content-Length</code>, while setting
425 <code>proxy-sendchunked</code> minimizes resource usage by using
426 chunked encoding.</p>
428 <p>Under some circumstances, the server must spool request bodies
429 to disk to satisfy the requested handling of request bodies. For
430 example, this spooling will occur if the original body was sent with
431 chunked encoding (and is large), but the administrator has
432 asked for backend requests to be sent with Content-Length or as HTTP/1.0.
433 This spooling can also occur if the request body already has a
434 Content-Length header, but the server is configured to filter incoming
437 <p><code class="directive"><a href="../mod/core.html#limitrequestbody">LimitRequestBody</a></code> only applies to
438 request bodies that the server will spool to disk</p>
440 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
441 <div class="section">
442 <h2><a name="x-headers" id="x-headers">Reverse Proxy Request Headers</a></h2>
444 <p>When acting in a reverse-proxy mode (using the <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive, for example),
445 <code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code> adds several request headers in
446 order to pass information to the origin server. These headers
450 <dt><code>X-Forwarded-For</code></dt>
451 <dd>The IP address of the client.</dd>
452 <dt><code>X-Forwarded-Host</code></dt>
453 <dd>The original host requested by the client in the <code>Host</code>
454 HTTP request header.</dd>
455 <dt><code>X-Forwarded-Server</code></dt>
456 <dd>The hostname of the proxy server.</dd>
459 <p>Be careful when using these headers on the origin server, since
460 they will contain more than one (comma-separated) value if the
461 original request already contained one of these headers. For
462 example, you can use <code>%{X-Forwarded-For}i</code> in the log
463 format string of the origin server to log the original clients IP
464 address, but you may get more than one address if the request
465 passes through several proxies.</p>
467 <p>See also the <code class="directive"><a href="#proxypreservehost">ProxyPreserveHost</a></code> and <code class="directive"><a href="#proxyvia">ProxyVia</a></code> directives, which control
468 other request headers.</p>
471 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
472 <div class="directive-section"><h2><a name="BalancerGrowth" id="BalancerGrowth">BalancerGrowth</a> <a name="balancergrowth" id="balancergrowth">Directive</a></h2>
473 <table class="directive">
474 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of additional Balancers that can be added Post-configuration</td></tr>
475 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>BalancerGrowth <var>#</var></code></td></tr>
476 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>BalancerGrowth 5</code></td></tr>
477 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
478 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
479 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
480 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>BalancerGrowth is only available in Apache HTTP Server 2.3.13
483 <p>This directive allows for growth potential in the number of
484 Balancers available for a virtualhost in addition to the
485 number pre-configured. It only takes effect if there is at
486 least 1 pre-configured Balancer.</p>
489 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
490 <div class="directive-section"><h2><a name="BalancerMember" id="BalancerMember">BalancerMember</a> <a name="balancermember" id="balancermember">Directive</a></h2>
491 <table class="directive">
492 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Add a member to a load balancing group</td></tr>
493 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>BalancerMember [<var>balancerurl</var>] <var>url</var> [<var>key=value [key=value ...]]</var></code></td></tr>
494 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
495 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
496 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
497 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>BalancerMember is only available in Apache HTTP Server 2.2
500 <p>This directive adds a member to a load balancing group. It could be used
501 within a <code><Proxy <var>balancer://</var>...></code> container
502 directive, and can take any of the key value pair parameters available to
503 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directives.</p>
504 <p>One additional parameter is available only to <code class="directive"><a href="#balancermember">BalancerMember</a></code> directives:
505 <var>loadfactor</var>. This is the member load factor - a number between 1
506 (default) and 100, which defines the weighted load to be applied to the
507 member in question.</p>
508 <p>The balancerurl is only needed when not in <code><Proxy <var>balancer://</var>...></code>
509 container directive. It corresponds to the url of a balancer defined in
510 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.</p>
513 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
514 <div class="directive-section"><h2><a name="NoProxy" id="NoProxy">NoProxy</a> <a name="noproxy" id="noproxy">Directive</a></h2>
515 <table class="directive">
516 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Hosts, domains, or networks that will be connected to
518 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NoProxy <var>host</var> [<var>host</var>] ...</code></td></tr>
519 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
520 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
521 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
523 <p>This directive is only useful for Apache httpd proxy servers within
524 intranets. The <code class="directive">NoProxy</code> directive specifies a
525 list of subnets, IP addresses, hosts and/or domains, separated by
526 spaces. A request to a host which matches one or more of these is
527 always served directly, without forwarding to the configured
528 <code class="directive"><a href="#proxyremote">ProxyRemote</a></code> proxy server(s).</p>
530 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">
531 ProxyRemote * http://firewall.example.com:81
532 NoProxy .example.com 192.168.112.0/21
536 <p>The <var>host</var> arguments to the <code class="directive">NoProxy</code>
537 directive are one of the following type list:</p>
541 <dt><var><a name="domain" id="domain">Domain</a></var></dt>
543 <p>A <dfn>Domain</dfn> is a partially qualified DNS domain name, preceded
544 by a period. It represents a list of hosts which logically belong to the
545 same DNS domain or zone (<em>i.e.</em>, the suffixes of the hostnames are
546 all ending in <var>Domain</var>).</p>
548 <div class="example"><h3>Examples</h3><p><code>
552 <p>To distinguish <var>Domain</var>s from <var><a href="#hostname">Hostname</a></var>s (both syntactically and semantically; a DNS domain can
553 have a DNS A record, too!), <var>Domain</var>s are always written with a
556 <div class="note"><h3>Note</h3>
557 <p>Domain name comparisons are done without regard to the case, and
558 <var>Domain</var>s are always assumed to be anchored in the root of the
559 DNS tree, therefore two domains <code>.ExAmple.com</code> and
560 <code>.example.com.</code> (note the trailing period) are considered
561 equal. Since a domain comparison does not involve a DNS lookup, it is much
562 more efficient than subnet comparison.</p>
566 <dt><var><a name="subnet" id="subnet">SubNet</a></var></dt>
568 <p>A <dfn>SubNet</dfn> is a partially qualified internet address in
569 numeric (dotted quad) form, optionally followed by a slash and the netmask,
570 specified as the number of significant bits in the <var>SubNet</var>. It is
571 used to represent a subnet of hosts which can be reached over a common
572 network interface. In the absence of the explicit net mask it is assumed
573 that omitted (or zero valued) trailing digits specify the mask. (In this
574 case, the netmask can only be multiples of 8 bits wide.) Examples:</p>
577 <dt><code>192.168</code> or <code>192.168.0.0</code></dt>
578 <dd>the subnet 192.168.0.0 with an implied netmask of 16 valid bits
579 (sometimes used in the netmask form <code>255.255.0.0</code>)</dd>
580 <dt><code>192.168.112.0/21</code></dt>
581 <dd>the subnet <code>192.168.112.0/21</code> with a netmask of 21
582 valid bits (also used in the form <code>255.255.248.0</code>)</dd>
585 <p>As a degenerate case, a <em>SubNet</em> with 32 valid bits is the
586 equivalent to an <var><a href="#ipaddr">IPAddr</a></var>, while a <var>SubNet</var> with zero
587 valid bits (<em>e.g.</em>, 0.0.0.0/0) is the same as the constant
588 <var>_Default_</var>, matching any IP address.</p></dd>
591 <dt><var><a name="ipaddr" id="ipaddr">IPAddr</a></var></dt>
593 <p>A <dfn>IPAddr</dfn> represents a fully qualified internet address in
594 numeric (dotted quad) form. Usually, this address represents a host, but
595 there need not necessarily be a DNS domain name connected with the
597 <div class="example"><h3>Example</h3><p><code>
601 <div class="note"><h3>Note</h3>
602 <p>An <var>IPAddr</var> does not need to be resolved by the DNS system, so
603 it can result in more effective apache performance.</p>
607 <dt><var><a name="hostname" id="hostname">Hostname</a></var></dt>
609 <p>A <dfn>Hostname</dfn> is a fully qualified DNS domain name which can
610 be resolved to one or more <var><a href="#ipaddr">IPAddrs</a></var> via the
611 DNS domain name service. It represents a logical host (in contrast to
612 <var><a href="#domain">Domain</a></var>s, see above) and must be resolvable
613 to at least one <var><a href="#ipaddr">IPAddr</a></var> (or often to a list
614 of hosts with different <var><a href="#ipaddr">IPAddr</a></var>s).</p>
616 <div class="example"><h3>Examples</h3><p><code>
617 prep.ai.example.edu<br />
621 <div class="note"><h3>Note</h3>
622 <p>In many situations, it is more effective to specify an <var><a href="#ipaddr">IPAddr</a></var> in place of a <var>Hostname</var> since a
623 DNS lookup can be avoided. Name resolution in Apache httpd can take a remarkable
624 deal of time when the connection to the name server uses a slow PPP
626 <p><var>Hostname</var> comparisons are done without regard to the case,
627 and <var>Hostname</var>s are always assumed to be anchored in the root
628 of the DNS tree, therefore two hosts <code>WWW.ExAmple.com</code>
629 and <code>www.example.com.</code> (note the trailing period) are
630 considered equal.</p>
636 <li><a href="../dns-caveats.html">DNS Issues</a></li>
639 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
640 <div class="directive-section"><h2><a name="Proxy" id="Proxy"><Proxy></a> <a name="proxy" id="proxy">Directive</a></h2>
641 <table class="directive">
642 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Container for directives applied to proxied resources</td></tr>
643 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Proxy <var>wildcard-url</var>> ...</Proxy></code></td></tr>
644 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
645 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
646 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
648 <p>Directives placed in <code class="directive"><Proxy></code>
649 sections apply only to matching proxied content. Shell-style wildcards are
652 <p>For example, the following will allow only hosts in
653 <code>yournetwork.example.com</code> to access content via your proxy
656 <pre class="prettyprint lang-config">
658 Require host yournetwork.example.com
663 <p>The following example will process all files in the <code>foo</code>
664 directory of <code>example.com</code> through the <code>INCLUDES</code>
665 filter when they are sent through the proxy server:</p>
667 <pre class="prettyprint lang-config">
668 <Proxy http://example.com/foo/*>
669 SetOutputFilter INCLUDES
677 <li><code class="directive"><a href="#proxymatch"><ProxyMatch></a></code></li>
680 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
681 <div class="directive-section"><h2><a name="ProxyAddHeaders" id="ProxyAddHeaders">ProxyAddHeaders</a> <a name="proxyaddheaders" id="proxyaddheaders">Directive</a></h2>
682 <table class="directive">
683 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Add proxy information in X-Forwarded-* headers</td></tr>
684 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyAddHeaders Off|On</code></td></tr>
685 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyAddHeaders On</code></td></tr>
686 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
687 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
688 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
689 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.3.10 and later</td></tr>
691 <p>This directive determines whether or not proxy related information should be passed to the
692 backend server through X-Forwarded-For, X-Forwarded-Host and X-Forwarded-Server HTTP headers.</p>
693 <div class="note"><h3>Effectiveness</h3>
694 <p>This option is of use only for HTTP proxying, as handled by <code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code>.</p>
698 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
699 <div class="directive-section"><h2><a name="ProxyBadHeader" id="ProxyBadHeader">ProxyBadHeader</a> <a name="proxybadheader" id="proxybadheader">Directive</a></h2>
700 <table class="directive">
701 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines how to handle bad header lines in a
703 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyBadHeader IsError|Ignore|StartBody</code></td></tr>
704 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyBadHeader IsError</code></td></tr>
705 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
706 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
707 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
708 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.0.44 and later</td></tr>
710 <p>The <code class="directive">ProxyBadHeader</code> directive determines the
711 behaviour of <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> if it receives syntactically invalid
712 response header lines (<em>i.e.</em> containing no colon) from the origin
713 server. The following arguments are possible:</p>
716 <dt><code>IsError</code></dt>
717 <dd>Abort the request and end up with a 502 (Bad Gateway) response. This is
718 the default behaviour.</dd>
720 <dt><code>Ignore</code></dt>
721 <dd>Treat bad header lines as if they weren't sent.</dd>
723 <dt><code>StartBody</code></dt>
724 <dd>When receiving the first bad header line, finish reading the headers and
725 treat the remainder as body. This helps to work around buggy backend servers
726 which forget to insert an empty line between the headers and the body.</dd>
730 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
731 <div class="directive-section"><h2><a name="ProxyBlock" id="ProxyBlock">ProxyBlock</a> <a name="proxyblock" id="proxyblock">Directive</a></h2>
732 <table class="directive">
733 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Words, hosts, or domains that are banned from being
735 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyBlock *|<var>word</var>|<var>host</var>|<var>domain</var>
736 [<var>word</var>|<var>host</var>|<var>domain</var>] ...</code></td></tr>
737 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
738 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
739 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
741 <p>The <code class="directive">ProxyBlock</code> directive specifies a list of
742 words, hosts and/or domains, separated by spaces. HTTP, HTTPS, and
743 FTP document requests to sites whose names contain matched words,
744 hosts or domains are <em>blocked</em> by the proxy server. The proxy
745 module will also attempt to determine IP addresses of list items which
746 may be hostnames during startup, and cache them for match test as
747 well. That may slow down the startup time of the server.</p>
749 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">
750 ProxyBlock news.example.com auctions.example.com friends.example.com
754 <p>Note that <code>example</code> would also be sufficient to match any
757 <p>Hosts would also be matched if referenced by IP address.</p>
759 <p>Note also that</p>
761 <pre class="prettyprint lang-config">
766 <p>blocks connections to all sites.</p>
769 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
770 <div class="directive-section"><h2><a name="ProxyDomain" id="ProxyDomain">ProxyDomain</a> <a name="proxydomain" id="proxydomain">Directive</a></h2>
771 <table class="directive">
772 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Default domain name for proxied requests</td></tr>
773 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyDomain <var>Domain</var></code></td></tr>
774 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
775 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
776 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
778 <p>This directive is only useful for Apache httpd proxy servers within
779 intranets. The <code class="directive">ProxyDomain</code> directive specifies
780 the default domain which the apache proxy server will belong to. If a
781 request to a host without a domain name is encountered, a redirection
782 response to the same host with the configured <var>Domain</var> appended
783 will be generated.</p>
785 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">
786 ProxyRemote * http://firewall.example.com:81<br />
787 NoProxy .example.com 192.168.112.0/21<br />
788 ProxyDomain .example.com
793 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
794 <div class="directive-section"><h2><a name="ProxyErrorOverride" id="ProxyErrorOverride">ProxyErrorOverride</a> <a name="proxyerroroverride" id="proxyerroroverride">Directive</a></h2>
795 <table class="directive">
796 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Override error pages for proxied content</td></tr>
797 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyErrorOverride On|Off</code></td></tr>
798 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyErrorOverride Off</code></td></tr>
799 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
800 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
801 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
802 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.0 and later</td></tr>
804 <p>This directive is useful for reverse-proxy setups, where you want to
805 have a common look and feel on the error pages seen by the end user.
806 This also allows for included files (via
807 <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>'s SSI) to get
808 the error code and act accordingly (default behavior would display
809 the error page of the proxied server, turning this on shows the SSI
812 <p>This directive does not affect the processing of informational (1xx),
813 normal success (2xx), or redirect (3xx) responses.</p>
816 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
817 <div class="directive-section"><h2><a name="ProxyIOBufferSize" id="ProxyIOBufferSize">ProxyIOBufferSize</a> <a name="proxyiobuffersize" id="proxyiobuffersize">Directive</a></h2>
818 <table class="directive">
819 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine size of internal data throughput buffer</td></tr>
820 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyIOBufferSize <var>bytes</var></code></td></tr>
821 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyIOBufferSize 8192</code></td></tr>
822 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
823 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
824 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
826 <p>The <code class="directive">ProxyIOBufferSize</code> directive adjusts the size
827 of the internal buffer, which is used as a scratchpad for the data between
828 input and output. The size must be at least <code>512</code>.</p>
830 <p>In almost every case there's no reason to change that value.</p>
831 <p>If used with AJP this directive sets the maximum AJP packet size in
832 bytes. If you change it from the default, you must also change the
833 <code>packetSize</code> attribute of your AJP connector on the
834 Tomcat side! The attribute <code>packetSize</code> is only available
835 in Tomcat <code>5.5.20+</code> and <code>6.0.2+</code></p>
836 <p>Normally it is not necessary to change the maximum packet size.
837 Problems with the default value have been reported when sending
838 certificates or certificate chains.</p>
842 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
843 <div class="directive-section"><h2><a name="ProxyMatch" id="ProxyMatch"><ProxyMatch></a> <a name="proxymatch" id="proxymatch">Directive</a></h2>
844 <table class="directive">
845 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Container for directives applied to regular-expression-matched
846 proxied resources</td></tr>
847 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><ProxyMatch <var>regex</var>> ...</ProxyMatch></code></td></tr>
848 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
849 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
850 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
852 <p>The <code class="directive"><ProxyMatch></code> directive is
853 identical to the <code class="directive"><a href="#proxy"><Proxy></a></code> directive, except it matches URLs
854 using <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expressions</a>.</p>
858 <li><code class="directive"><a href="#proxy"><Proxy></a></code></li>
861 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
862 <div class="directive-section"><h2><a name="ProxyMaxForwards" id="ProxyMaxForwards">ProxyMaxForwards</a> <a name="proxymaxforwards" id="proxymaxforwards">Directive</a></h2>
863 <table class="directive">
864 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximium number of proxies that a request can be forwarded
866 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyMaxForwards <var>number</var></code></td></tr>
867 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyMaxForwards -1</code></td></tr>
868 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
869 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
870 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
871 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.0 and later;
872 default behaviour changed in 2.2.7/2.3</td></tr>
874 <p>The <code class="directive">ProxyMaxForwards</code> directive specifies the
875 maximum number of proxies through which a request may pass, if there's no
876 <code>Max-Forwards</code> header supplied with the request. This may
877 be set to prevent infinite proxy loops, or a DoS attack.</p>
879 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">
884 <p>Note that setting <code class="directive">ProxyMaxForwards</code> is a
885 violation of the HTTP/1.1 protocol (RFC2616), which forbids a Proxy
886 setting <code>Max-Forwards</code> if the Client didn't set it.
887 Earlier Apache httpd versions would always set it. A negative
888 <code class="directive">ProxyMaxForwards</code> value, including the
889 default -1, gives you protocol-compliant behaviour, but may
890 leave you open to loops.</p>
893 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
894 <div class="directive-section"><h2><a name="ProxyPass" id="ProxyPass">ProxyPass</a> <a name="proxypass" id="proxypass">Directive</a></h2>
895 <table class="directive">
896 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maps remote servers into the local server URL-space</td></tr>
897 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPass [<var>path</var>] !|<var>url</var> [<var>key=value</var>
898 <var>[key=value</var> ...]] [nocanon] [interpolate] [noquery]</code></td></tr>
899 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
900 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
901 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
903 <p>This directive allows remote servers to be mapped into the
904 space of the local server; the local server does not act as a
905 proxy in the conventional sense, but appears to be a mirror of the
906 remote server. The local server is often called a <dfn>reverse
907 proxy</dfn> or <dfn>gateway</dfn>. The <var>path</var> is the name of
908 a local virtual path; <var>url</var> is a partial URL for the
909 remote server and cannot include a query string.</p>
911 <div class="warning">The <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> directive should
912 usually be set <strong>off</strong> when using
913 <code class="directive">ProxyPass</code>.</div>
915 <p>Suppose the local server has address <code>http://example.com/</code>;
918 <pre class="prettyprint lang-config">
919 <Location /mirror/foo/>
920 ProxyPass http://backend.example.com/
925 <p>will cause a local request for
926 <code>http://example.com/mirror/foo/bar</code> to be internally converted
927 into a proxy request to <code>http://backend.example.com/bar</code>.</p>
929 <p>The following alternative syntax is possible, however it can carry a
930 performance penalty when present in very large numbers. The advantage of
931 the below syntax is that it allows for dynamic control via the
932 <a href="mod_proxy_balancer.html#balancer_manager">Balancer Manager</a> interface:</p>
934 <pre class="prettyprint lang-config">
935 ProxyPass /mirror/foo/ http://backend.example.com/
939 <div class="warning">
940 <p>If the first argument ends with a trailing <strong>/</strong>, the second
941 argument should also end with a trailing <strong>/</strong> and vice
942 versa. Otherwise the resulting requests to the backend may miss some
943 needed slashes and do not deliver the expected results.
947 <p>The <code>!</code> directive is useful in situations where you don't want
948 to reverse-proxy a subdirectory, <em>e.g.</em></p>
950 <pre class="prettyprint lang-config">
951 <Location /mirror/foo/>
952 ProxyPass http://backend.example.com/
954 <Location /mirror/foo/i>
960 <pre class="prettyprint lang-config">
961 ProxyPass /mirror/foo/i !
962 ProxyPass /mirror/foo http://backend.example.com
966 <p>will proxy all requests to <code>/mirror/foo</code> to
967 <code>backend.example.com</code> <em>except</em> requests made to
968 <code>/mirror/foo/i</code>.</p>
970 <div class="warning"><h3>Ordering ProxyPass Directives</h3>
971 <p>The configured <code class="directive"><a href="#proxypass">ProxyPass</a></code>
972 and <code class="directive"><a href="#proxypassmatch">ProxyPassMatch</a></code>
973 rules are checked in the order of configuration. The first rule that
974 matches wins. So usually you should sort conflicting
975 <code class="directive"><a href="#proxypass">ProxyPass</a></code> rules starting with the
976 longest URLs first. Otherwise later rules for longer URLS will be hidden
977 by any earlier rule which uses a leading substring of the URL. Note that
978 there is some relation with worker sharing. In contrast, only one
979 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive can be placed
980 in a <code class="directive"><a href="../mod/core.html#location">Location</a></code> block, and the most
981 specific location will take precedence.</p>
983 <p>For the same reasons exclusions must come <em>before</em> the
984 general <code class="directive">ProxyPass</code> directives.</p>
988 <p>In Apache HTTP Server 2.1 and later, mod_proxy supports pooled
989 connections to a backend server. Connections created on demand
990 can be retained in a pool for future use. Limits on the pool size
991 and other settings can be coded on
992 the <code class="directive">ProxyPass</code> directive
993 using <code>key=value</code> parameters, described in the table
996 <p>By default, mod_proxy will allow and retain the maximum number of
997 connections that could be used simultaneously by that web server child
998 process. Use the <code>max</code> parameter to reduce the number from
999 the default. Use the <code>ttl</code> parameter to set an optional
1000 time to live; connections which have been unused for at least
1001 <code>ttl</code> seconds will be closed. <code>ttl</code> can be used
1002 to avoid using a connection which is subject to closing because of the
1003 backend server's keep-alive timeout.</p>
1005 <p>The pool of connections is maintained per web server child
1006 process, and <code>max</code> and other settings are not coordinated
1007 among all child processes, except when only one child process is allowed
1008 by configuration or MPM design.</p>
1010 <div class="example"><h3>Example</h3><p><code>
1011 ProxyPass /example http://backend.example.com max=20 ttl=120 retry=300
1014 <table class="bordered"><tr><th>BalancerMember parameters</th></tr></table>
1016 <tr><th>Parameter</th>
1018 <th>Description</th></tr>
1021 <td>Minimum number of connection pool entries, unrelated to the
1022 actual number of connections. This only needs to be modified from the
1023 default for special circumstances where heap memory associated with the
1024 backend connections should be preallocated or retained.</td></tr>
1027 <td>Maximum number of connections that will be allowed to the
1028 backend server. The default for this limit is the number of threads
1029 per process in the active MPM. In the Prefork MPM, this is always 1,
1030 while with other MPMs it is controlled by the
1031 <code class="directive">ThreadsPerChild</code> directive.</td></tr>
1034 <td>Retained connection pool entries above this limit are freed
1035 during certain operations if they have been unused for longer than
1036 the time to live, controlled by the <code>ttl</code> parameter. If
1037 the connection pool entry has an associated connection, it will be
1038 closed. This only needs to be modified from the default for special
1039 circumstances where connection pool entries and any associated
1040 connections which have exceeded the time to live need to be freed or
1041 closed more aggressively.</td></tr>
1042 <tr><td>acquire</td>
1044 <td>If set this will be the maximum time to wait for a free
1045 connection in the connection pool, in milliseconds. If there are no free
1046 connections in the pool the Apache httpd will return <code>SERVER_BUSY</code>
1047 status to the client.
1049 <tr><td>connectiontimeout</td>
1051 <td>Connect timeout in seconds.
1052 The number of seconds Apache httpd waits for the creation of a connection to
1053 the backend to complete. By adding a postfix of ms the timeout can be
1054 also set in milliseconds.
1056 <tr><td>disablereuse</td>
1058 <td>This parameter should be used when you want to force mod_proxy
1059 to immediately close a connection to the backend after being used, and
1060 thus, disable its persistent connection and pool for that backend.
1061 This helps in various situations where a firewall between Apache
1063 the backend server (regardless of protocol) tends to silently
1064 drop connections or when backends themselves may be under round-
1065 robin DNS. To disable connection pooling reuse,
1066 set this property value to <code>On</code>.
1068 <tr><td>flushpackets</td>
1070 <td>Determines whether the proxy module will auto-flush the output
1071 brigade after each "chunk" of data. 'off' means that it will flush
1072 only when needed, 'on' means after each chunk is sent and
1073 'auto' means poll/wait for a period of time and flush if
1074 no input has been received for 'flushwait' milliseconds.
1075 Currently this is in effect only for AJP.
1077 <tr><td>flushwait</td>
1079 <td>The time to wait for additional input, in milliseconds, before
1080 flushing the output brigade if 'flushpackets' is 'auto'.
1082 <tr><td>iobuffersize</td>
1084 <td>Adjusts the size of the internal scratchpad IO buffer. This allows you
1085 to override the <code class="directive">ProxyIOBufferSize</code> for a specific worker.
1086 This must be at least 512 or set to 0 for the system default of 8192.
1088 <tr><td>keepalive</td>
1090 <td><p>This parameter should be used when you have a firewall between your
1091 Apache httpd and the backend server, who tend to drop inactive connections.
1092 This flag will tell the Operating System to send <code>KEEP_ALIVE</code>
1093 messages on inactive connections and thus prevent the firewall to drop the connection.
1094 To enable keepalive set this property value to <code>On</code>. </p>
1095 <p>The frequency of initial and subsequent TCP keepalive probes
1096 depends on global OS settings, and may be as high as 2 hours. To be useful,
1097 the frequency configured in the OS must be smaller than the threshold used
1098 by the firewall.</p>
1102 <td>Sets the load balancer cluster set that the worker is a member
1103 of. The load balancer will try all members of a lower numbered
1104 lbset before trying higher numbered ones.
1108 <td>Ping property tells the webserver to "test" the connection to
1109 the backend before forwarding the request. For AJP, it causes
1110 <code class="module"><a href="../mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code>to send a <code>CPING</code>
1111 request on the ajp13 connection (implemented on Tomcat 3.3.2+, 4.1.28+
1112 and 5.0.13+). For HTTP, it causes <code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code>
1113 to send a <code>100-Continue</code> to the backend (only valid for
1114 HTTP/1.1 - for non HTTP/1.1 backends, this property has no
1115 effect). In both cases the parameter is the delay in seconds to wait
1117 This feature has been added to avoid problems with hung and
1119 This will increase the network traffic during the normal operation
1120 which could be an issue, but it will lower the
1121 traffic in case some of the cluster nodes are down or busy.
1122 By adding a postfix of ms the delay can be also set in
1125 <tr><td>receivebuffersize</td>
1127 <td>Adjusts the size of the explicit (TCP/IP) network buffer size for
1128 proxied connections. This allows you to override the
1129 <code class="directive">ProxyReceiveBufferSize</code> for a specific worker.
1130 This must be at least 512 or set to 0 for the system default.
1132 <tr><td>redirect</td>
1134 <td>Redirection Route of the worker. This value is usually
1135 set dynamically to enable safe removal of the node from
1136 the cluster. If set all requests without session id will be
1137 redirected to the BalancerMember that has route parameter
1138 equal as this value.
1142 <td>Connection pool worker retry timeout in seconds.
1143 If the connection pool worker to the backend server is in the error state,
1144 Apache httpd will not forward any requests to that server until the timeout
1145 expires. This enables to shut down the backend server for maintenance,
1146 and bring it back online later. A value of 0 means always retry workers
1147 in an error state with no timeout.
1151 <td>Route of the worker when used inside load balancer.
1152 The route is a value appended to session id.
1156 <td>Single letter value defining the initial status of
1159 <tr><td>D: Worker is disabled and will not accept any requests.</td></tr>
1160 <tr><td>S: Worker is administratively stopped.</td></tr>
1161 <tr><td>I: Worker is in ignore-errors mode, and will always be considered available.</td></tr>
1162 <tr><td>H: Worker is in hot-standby mode and will only be used if no other
1163 viable workers are available.</td></tr>
1164 <tr><td>E: Worker is in an error state.</td></tr>
1165 <tr><td>N: Worker is in drain mode, and will only accept existing sticky sessions
1166 destined for itself and ignore all other requests.</td></tr>
1168 can be set (which is the default) by prepending with '+' or
1169 cleared by prepending with '-'.
1170 Thus, a setting of 'S-E' sets this worker to Stopped and
1171 clears the in-error flag.
1173 <tr><td>timeout</td>
1174 <td><code class="directive"><a href="#proxytimeout">ProxyTimeout</a></code></td>
1175 <td>Connection timeout in seconds.
1176 The number of seconds Apache httpd waits for data sent by / to the backend.
1180 <td>Time to live for inactive connections and associated connection
1181 pool entries, in seconds. Once reaching this limit, a
1182 connection will not be used again; it will be closed at some
1188 <p>If the Proxy directive scheme starts with the
1189 <code>balancer://</code> (eg: <code>balancer://cluster/</code>,
1190 any path information is ignored) then a virtual worker that does not really
1191 communicate with the backend server will be created. Instead it is responsible
1192 for the management of several "real" workers. In that case the special set of
1193 parameters can be add to this virtual worker. See <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code>
1194 for more information about how the balancer works.
1196 <table class="bordered"><tr><th>Balancer parameters</th></tr></table>
1198 <tr><th>Parameter</th>
1200 <th>Description</th></tr>
1201 <tr><td>lbmethod</td>
1203 <td>Balancer load-balance method. Select the load-balancing scheduler
1204 method to use. Either <code>byrequests</code>, to perform weighted
1205 request counting, <code>bytraffic</code>, to perform weighted
1206 traffic byte count balancing, or <code>bybusyness</code>, to perform
1207 pending request balancing. Default is <code>byrequests</code>.
1209 <tr><td>maxattempts</td>
1210 <td>One less than the number of workers, or 1 with a single worker.</td>
1211 <td>Maximum number of failover attempts before giving up.
1213 <tr><td>nofailover</td>
1215 <td>If set to <code>On</code> the session will break if the worker is in
1216 error state or disabled. Set this value to On if backend servers do not
1217 support session replication.
1219 <tr><td>stickysession</td>
1221 <td>Balancer sticky session name. The value is usually set to something
1222 like <code>JSESSIONID</code> or <code>PHPSESSIONID</code>,
1223 and it depends on the backend application server that support sessions.
1224 If the backend application server uses different name for cookies
1225 and url encoded id (like servlet containers) use | to to separate them.
1226 The first part is for the cookie the second for the path.
1228 <tr><td>scolonpathdelim</td>
1230 <td>If set to <code>On</code> the semi-colon character ';' will be
1231 used as an additional sticky session path deliminator/separator. This
1232 is mainly used to emulate mod_jk's behavior when dealing with paths such
1233 as <code>JSESSIONID=6736bcf34;foo=aabfa</code>
1235 <tr><td>timeout</td>
1237 <td>Balancer timeout in seconds. If set this will be the maximum time
1238 to wait for a free worker. Default is not to wait.
1240 <tr><td>failonstatus</td>
1242 <td>A single or comma-separated list of HTTP status codes. If set this will
1243 force the worker into error state when the backend returns any status code
1244 in the list. Worker recovery behaves the same as other worker errors.
1247 <td><auto></td>
1248 <td>The protective nonce used in the <code>balancer-manager</code> application page.
1249 The default is to use an automatically determined UUID-based
1250 nonce, to provide for further protection for the page. If set,
1251 then the nonce is set to that value. A setting of <code>None</code>
1252 disables all nonce checking.
1253 <div class="note"><h3>Note</h3>
1254 <p>In addition to the nonce, the <code>balancer-manager</code> page
1255 should be protected via an ACL.</p>
1260 <td>Number of additional BalancerMembers to allow to be added
1261 to this balancer in addition to those defined at configuration.
1263 <tr><td>forcerecovery</td>
1265 <td>Force the immediate recovery of all workers without considering the
1266 retry parameter of the workers if all workers of a balancer are
1267 in error state. There might be cases where an already overloaded backend
1268 can get into deeper trouble if the recovery of all workers is enforced
1269 without considering the retry parameter of each worker. In this case
1270 set to <code>Off</code>.
1274 <p>A sample balancer setup</p>
1275 <pre class="prettyprint lang-config">
1276 ProxyPass /special-area http://special.example.com smax=5 max=10
1277 ProxyPass / balancer://mycluster/ stickysession=JSESSIONID|jsessionid nofailover=On
1278 <Proxy balancer://mycluster>
1279 BalancerMember ajp://1.2.3.4:8009
1280 BalancerMember ajp://1.2.3.5:8009 loadfactor=20
1281 # Less powerful server, don't send as many requests there,
1282 BalancerMember ajp://1.2.3.6:8009 loadfactor=5
1287 <p>Setting up a hot-standby, that will only be used if no other
1288 members are available</p>
1289 <pre class="prettyprint lang-config">
1290 ProxyPass / balancer://hotcluster/
1291 <Proxy balancer://hotcluster>
1292 BalancerMember ajp://1.2.3.4:8009 loadfactor=1
1293 BalancerMember ajp://1.2.3.5:8009 loadfactor=2
1294 # The server below is on hot standby
1295 BalancerMember ajp://1.2.3.6:8009 status=+H
1296 ProxySet lbmethod=bytraffic
1301 <p>Normally, mod_proxy will canonicalise ProxyPassed URLs.
1302 But this may be incompatible with some backends, particularly those
1303 that make use of <var>PATH_INFO</var>. The optional <var>nocanon</var>
1304 keyword suppresses this, and passes the URL path "raw" to the
1305 backend. Note that may affect the security of your backend, as it
1306 removes the normal limited protection against URL-based attacks
1307 provided by the proxy.</p>
1309 <p>The optional <var>interpolate</var> keyword (available in
1310 httpd 2.2.9 and later), in combination with
1311 <code class="directive">ProxyPassInterpolateEnv</code> causes the ProxyPass
1312 to interpolate environment variables, using the syntax
1313 <var>${VARNAME}</var>. Note that many of the standard CGI-derived
1314 environment variables will not exist when this interpolation happens,
1315 so you may still have to resort to <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
1316 for complex rules.</p>
1318 <p>Normally, mod_proxy will include the query string when
1319 generating the <var>SCRIPT_FILENAME</var> environment variable.
1320 The optional <var>noquery</var> keyword (available in
1321 httpd 2.4.1 and later) prevents this.</p>
1323 <p>When used inside a <code class="directive"><a href="../mod/core.html#location"><Location></a></code> section, the first argument is omitted and the local
1324 directory is obtained from the <code class="directive"><a href="../mod/core.html#location"><Location></a></code>. The same will occur inside a
1325 <code class="directive"><a href="../mod/core.html#locationmatch"><LocationMatch></a></code> section,
1326 however ProxyPass does not interpret the regexp as such, so it is necessary
1327 to use <code class="directive">ProxyPassMatch</code> in this situation instead.</p>
1329 <p>This directive is not supported in <code class="directive"><a href="../mod/core.html#directory"><Directory></a></code> or <code class="directive"><a href="../mod/core.html#files"><Files></a></code> sections.</p>
1331 <p>If you require a more flexible reverse-proxy configuration, see the
1332 <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directive with the
1333 <code>[P]</code> flag.</p>
1337 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1338 <div class="directive-section"><h2><a name="ProxyPassInterpolateEnv" id="ProxyPassInterpolateEnv">ProxyPassInterpolateEnv</a> <a name="proxypassinterpolateenv" id="proxypassinterpolateenv">Directive</a></h2>
1339 <table class="directive">
1340 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable Environment Variable interpolation in Reverse Proxy configurations</td></tr>
1341 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassInterpolateEnv On|Off</code></td></tr>
1342 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyPassInterpolateEnv Off</code></td></tr>
1343 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1344 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1345 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1346 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in httpd 2.2.9 and later</td></tr>
1348 <p>This directive, together with the <var>interpolate</var> argument to
1349 <code class="directive">ProxyPass</code>, <code class="directive">ProxyPassReverse</code>,
1350 <code class="directive">ProxyPassReverseCookieDomain</code> and
1351 <code class="directive">ProxyPassReverseCookiePath</code>
1352 enables reverse proxies to be dynamically
1353 configured using environment variables, which may be set by
1354 another module such as <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>.
1355 It affects the <code class="directive">ProxyPass</code>,
1356 <code class="directive">ProxyPassReverse</code>,
1357 <code class="directive">ProxyPassReverseCookieDomain</code>, and
1358 <code class="directive">ProxyPassReverseCookiePath</code> directives,
1359 and causes them to substitute the value of an environment
1360 variable <code>varname</code> for the string <code>${varname}</code>
1361 in configuration directives (if the <var>interpolate</var> option is set).</p>
1362 <p>Keep this turned off (for server performance) unless you need it!</p>
1365 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1366 <div class="directive-section"><h2><a name="ProxyPassMatch" id="ProxyPassMatch">ProxyPassMatch</a> <a name="proxypassmatch" id="proxypassmatch">Directive</a></h2>
1367 <table class="directive">
1368 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maps remote servers into the local server URL-space using regular expressions</td></tr>
1369 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassMatch [<var>regex</var>] !|<var>url</var> [<var>key=value</var>
1370 <var>[key=value</var> ...]]</code></td></tr>
1371 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1372 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1373 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1375 <p>This directive is equivalent to <code class="directive"><a href="#proxypass">ProxyPass</a></code>,
1376 but makes use of regular expressions, instead of simple prefix matching. The
1377 supplied regular expression is matched against the <var>url</var>, and if it
1378 matches, the server will substitute any parenthesized matches into the given
1379 string and use it as a new <var>url</var>.</p>
1381 <p>Suppose the local server has address <code>http://example.com/</code>;
1384 <pre class="prettyprint lang-config">
1385 ProxyPassMatch ^(/.*\.gif)$ http://backend.example.com$1
1389 <p>will cause a local request for
1390 <code>http://example.com/foo/bar.gif</code> to be internally converted
1391 into a proxy request to <code>http://backend.example.com/foo/bar.gif</code>.</p>
1392 <div class="note"><h3>Note</h3>
1393 <p>The URL argument must be parsable as a URL <em>before</em> regexp
1394 substitutions (as well as after). This limits the matches you can use.
1395 For instance, if we had used</p>
1396 <pre class="prettyprint lang-config">
1397 ProxyPassMatch ^(/.*\.gif)$ http://backend.example.com:8000$1
1400 <p>in our previous example, it would fail with a syntax error
1401 at server startup. This is a bug (PR 46665 in the ASF bugzilla),
1402 and the workaround is to reformulate the match:</p>
1403 <pre class="prettyprint lang-config">
1404 ProxyPassMatch ^/(.*\.gif)$ http://backend.example.com:8000/$1
1408 <p>The <code>!</code> directive is useful in situations where you don't want
1409 to reverse-proxy a subdirectory.</p>
1411 <p>When used inside a <code class="directive"><a href="../mod/core.html#locationmatch"><LocationMatch></a></code> section, the first argument is omitted and the
1412 regexp is obtained from the <code class="directive"><a href="../mod/core.html#locationmatch"><LocationMatch></a></code>.</p>
1414 <p>If you require a more flexible reverse-proxy configuration, see the
1415 <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directive with the
1416 <code>[P]</code> flag.</p>
1418 <div class="warning">
1419 <h3>Security Warning</h3>
1420 <p>Take care when constructing the target URL of the rule, considering
1421 the security impact from allowing the client influence over the set of
1422 URLs to which your server will act as a proxy. Ensure that the scheme
1423 and hostname part of the URL is either fixed, or does not allow the
1424 client undue influence.</p>
1428 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1429 <div class="directive-section"><h2><a name="ProxyPassReverse" id="ProxyPassReverse">ProxyPassReverse</a> <a name="proxypassreverse" id="proxypassreverse">Directive</a></h2>
1430 <table class="directive">
1431 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Adjusts the URL in HTTP response headers sent from a reverse
1432 proxied server</td></tr>
1433 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassReverse [<var>path</var>] <var>url</var>
1434 [<var>interpolate</var>]</code></td></tr>
1435 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1436 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1437 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1439 <p>This directive lets Apache httpd adjust the URL in the <code>Location</code>,
1440 <code>Content-Location</code> and <code>URI</code> headers on HTTP
1441 redirect responses. This is essential when Apache httpd is used as a
1442 reverse proxy (or gateway) to avoid by-passing the reverse proxy
1443 because of HTTP redirects on the backend servers which stay behind
1444 the reverse proxy.</p>
1446 <p>Only the HTTP response headers specifically mentioned above
1447 will be rewritten. Apache httpd will not rewrite other response
1448 headers, nor will it rewrite URL references inside HTML pages.
1449 This means that if the proxied content contains absolute URL
1450 references, they will by-pass the proxy. A third-party module
1451 that will look inside the HTML and rewrite URL references is Nick
1452 Kew's <a href="http://apache.webthing.com/mod_proxy_html/">mod_proxy_html</a>.</p>
1454 <p><var>path</var> is the name of a local virtual path. <var>url</var> is a
1455 partial URL for the remote server - the same way they are used for the
1456 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.</p>
1458 <p>For example, suppose the local server has address
1459 <code>http://example.com/</code>; then</p>
1461 <pre class="prettyprint lang-config">
1462 ProxyPass /mirror/foo/ http://backend.example.com/
1463 ProxyPassReverse /mirror/foo/ http://backend.example.com/
1464 ProxyPassReverseCookieDomain backend.example.com public.example.com
1465 ProxyPassReverseCookiePath / /mirror/foo/
1469 <p>will not only cause a local request for the
1470 <code>http://example.com/mirror/foo/bar</code> to be internally converted
1471 into a proxy request to <code>http://backend.example.com/bar</code>
1472 (the functionality <code>ProxyPass</code> provides here). It also takes care
1473 of redirects the server <code>backend.example.com</code> sends: when
1474 <code>http://backend.example.com/bar</code> is redirected by him to
1475 <code>http://backend.example.com/quux</code> Apache httpd adjusts this to
1476 <code>http://example.com/mirror/foo/quux</code> before forwarding the HTTP
1477 redirect response to the client. Note that the hostname used for
1478 constructing the URL is chosen in respect to the setting of the <code class="directive"><a href="../mod/core.html#usecanonicalname">UseCanonicalName</a></code> directive.</p>
1480 <p>Note that this <code class="directive">ProxyPassReverse</code> directive can
1481 also be used in conjunction with the proxy pass-through feature
1482 (<code>RewriteRule ... [P]</code>) from <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
1483 because it doesn't depend on a corresponding <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.</p>
1485 <p>The optional <var>interpolate</var> keyword (available in
1486 httpd 2.2.9 and later), used together with
1487 <code class="directive">ProxyPassInterpolateEnv</code>, enables interpolation
1488 of environment variables specified using the format <var>${VARNAME}</var>.
1491 <p>When used inside a <code class="directive"><a href="../mod/core.html#location"><Location></a></code> section, the first argument is omitted and the local
1492 directory is obtained from the <code class="directive"><a href="../mod/core.html#location"><Location></a></code>. The same occurs inside a <code class="directive"><a href="../mod/core.html#locationmatch"><LocationMatch></a></code> section, but will probably not work as
1493 intended, as ProxyPassReverse will interpret the regexp literally as a
1494 path; if needed in this situation, specify the ProxyPassReverse outside
1495 the section, or in a separate <code class="directive"><a href="../mod/core.html#location"><Location></a></code> section.</p>
1497 <p>This directive is not supported in <code class="directive"><a href="../mod/core.html#directory"><Directory></a></code> or <code class="directive"><a href="../mod/core.html#files"><Files></a></code> sections.</p>
1500 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1501 <div class="directive-section"><h2><a name="ProxyPassReverseCookieDomain" id="ProxyPassReverseCookieDomain">ProxyPassReverseCookieDomain</a> <a name="proxypassreversecookiedomain" id="proxypassreversecookiedomain">Directive</a></h2>
1502 <table class="directive">
1503 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Adjusts the Domain string in Set-Cookie headers from a reverse-
1504 proxied server</td></tr>
1505 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassReverseCookieDomain <var>internal-domain</var>
1506 <var>public-domain</var> [<var>interpolate</var>]</code></td></tr>
1507 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1508 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1509 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1511 <p>Usage is basically similar to
1512 <code class="directive"><a href="#proxypassreverse">ProxyPassReverse</a></code>, but instead of
1513 rewriting headers that are a URL, this rewrites the <code>domain</code>
1514 string in <code>Set-Cookie</code> headers.</p>
1517 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1518 <div class="directive-section"><h2><a name="ProxyPassReverseCookiePath" id="ProxyPassReverseCookiePath">ProxyPassReverseCookiePath</a> <a name="proxypassreversecookiepath" id="proxypassreversecookiepath">Directive</a></h2>
1519 <table class="directive">
1520 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Adjusts the Path string in Set-Cookie headers from a reverse-
1521 proxied server</td></tr>
1522 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassReverseCookiePath <var>internal-path</var>
1523 <var>public-path</var> [<var>interpolate</var>]</code></td></tr>
1524 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1525 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1526 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1529 Useful in conjunction with
1530 <code class="directive"><a href="#proxypassreverse">ProxyPassReverse</a></code>
1531 in situations where backend URL paths are mapped to public paths on the
1532 reverse proxy. This directive rewrites the <code>path</code> string in
1533 <code>Set-Cookie</code> headers. If the beginning of the cookie path matches
1534 <var>internal-path</var>, the cookie path will be replaced with
1535 <var>public-path</var>.
1537 In the example given with
1538 <code class="directive"><a href="#proxypassreverse">ProxyPassReverse</a></code>, the directive:
1540 <pre class="prettyprint lang-config">
1541 ProxyPassReverseCookiePath / /mirror/foo/
1545 will rewrite a cookie with backend path <code>/</code> (or
1546 <code>/example</code> or, in fact, anything) to <code>/mirror/foo/</code>.
1550 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1551 <div class="directive-section"><h2><a name="ProxyPreserveHost" id="ProxyPreserveHost">ProxyPreserveHost</a> <a name="proxypreservehost" id="proxypreservehost">Directive</a></h2>
1552 <table class="directive">
1553 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use incoming Host HTTP request header for proxy
1555 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPreserveHost On|Off</code></td></tr>
1556 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyPreserveHost Off</code></td></tr>
1557 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1558 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1559 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1560 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.0.31 and later. Usable in directory
1561 context in 2.3.3 and later.</td></tr>
1563 <p>When enabled, this option will pass the Host: line from the incoming
1564 request to the proxied host, instead of the hostname specified in the
1565 <code class="directive">ProxyPass</code> line.</p>
1567 <p>This option should normally be turned <code>Off</code>. It is mostly
1568 useful in special configurations like proxied mass name-based virtual
1569 hosting, where the original Host header needs to be evaluated by the
1573 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1574 <div class="directive-section"><h2><a name="ProxyReceiveBufferSize" id="ProxyReceiveBufferSize">ProxyReceiveBufferSize</a> <a name="proxyreceivebuffersize" id="proxyreceivebuffersize">Directive</a></h2>
1575 <table class="directive">
1576 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Network buffer size for proxied HTTP and FTP
1577 connections</td></tr>
1578 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyReceiveBufferSize <var>bytes</var></code></td></tr>
1579 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyReceiveBufferSize 0</code></td></tr>
1580 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1581 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1582 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1584 <p>The <code class="directive">ProxyReceiveBufferSize</code> directive specifies an
1585 explicit (TCP/IP) network buffer size for proxied HTTP and FTP connections,
1586 for increased throughput. It has to be greater than <code>512</code> or set
1587 to <code>0</code> to indicate that the system's default buffer size should
1590 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">
1591 ProxyReceiveBufferSize 2048
1596 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1597 <div class="directive-section"><h2><a name="ProxyRemote" id="ProxyRemote">ProxyRemote</a> <a name="proxyremote" id="proxyremote">Directive</a></h2>
1598 <table class="directive">
1599 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Remote proxy used to handle certain requests</td></tr>
1600 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyRemote <var>match</var> <var>remote-server</var></code></td></tr>
1601 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1602 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1603 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1605 <p>This defines remote proxies to this proxy. <var>match</var> is either the
1606 name of a URL-scheme that the remote server supports, or a partial URL
1607 for which the remote server should be used, or <code>*</code> to indicate
1608 the server should be contacted for all requests. <var>remote-server</var> is
1609 a partial URL for the remote server. Syntax:</p>
1611 <div class="example"><p><code>
1612 <dfn>remote-server</dfn> =
1613 <var>scheme</var>://<var>hostname</var>[:<var>port</var>]
1616 <p><var>scheme</var> is effectively the protocol that should be used to
1617 communicate with the remote server; only <code>http</code> and <code>https</code>
1618 are supported by this module. When using <code>https</code>, the requests
1619 are forwarded through the remote proxy using the HTTP CONNECT method.</p>
1621 <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">
1622 ProxyRemote http://goodguys.example.com/ http://mirrorguys.example.com:8000
1623 ProxyRemote * http://cleverproxy.localdomain
1624 ProxyRemote ftp http://ftpproxy.mydomain:8080
1628 <p>In the last example, the proxy will forward FTP requests, encapsulated
1629 as yet another HTTP proxy request, to another proxy which can handle
1632 <p>This option also supports reverse proxy configuration - a backend
1633 webserver can be embedded within a virtualhost URL space even if that
1634 server is hidden by another forward proxy.</p>
1637 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1638 <div class="directive-section"><h2><a name="ProxyRemoteMatch" id="ProxyRemoteMatch">ProxyRemoteMatch</a> <a name="proxyremotematch" id="proxyremotematch">Directive</a></h2>
1639 <table class="directive">
1640 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Remote proxy used to handle requests matched by regular
1641 expressions</td></tr>
1642 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyRemoteMatch <var>regex</var> <var>remote-server</var></code></td></tr>
1643 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1644 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1645 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1647 <p>The <code class="directive">ProxyRemoteMatch</code> is identical to the
1648 <code class="directive"><a href="#proxyremote">ProxyRemote</a></code> directive, except the
1649 first argument is a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>
1650 match against the requested URL.</p>
1653 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1654 <div class="directive-section"><h2><a name="ProxyRequests" id="ProxyRequests">ProxyRequests</a> <a name="proxyrequests" id="proxyrequests">Directive</a></h2>
1655 <table class="directive">
1656 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables forward (standard) proxy requests</td></tr>
1657 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyRequests On|Off</code></td></tr>
1658 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyRequests Off</code></td></tr>
1659 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1660 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1661 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1663 <p>This allows or prevents Apache httpd from functioning as a forward proxy
1664 server. (Setting ProxyRequests to <code>Off</code> does not disable use of
1665 the <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.)</p>
1667 <p>In a typical reverse proxy or gateway configuration, this
1668 option should be set to
1669 <code>Off</code>.</p>
1671 <p>In order to get the functionality of proxying HTTP or FTP sites, you
1672 need also <code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code> or <code class="module"><a href="../mod/mod_proxy_ftp.html">mod_proxy_ftp</a></code>
1673 (or both) present in the server.</p>
1675 <div class="warning"><h3>Warning</h3>
1676 <p>Do not enable proxying with <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> until you have <a href="#access">secured your server</a>. Open proxy servers are dangerous
1677 both to your network and to the Internet at large.</p>
1682 <li><a href="#forwardreverse">Forward and Reverse Proxies/Gateways</a></li>
1685 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1686 <div class="directive-section"><h2><a name="ProxySet" id="ProxySet">ProxySet</a> <a name="proxyset" id="proxyset">Directive</a></h2>
1687 <table class="directive">
1688 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Set various Proxy balancer or member parameters</td></tr>
1689 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxySet <var>url</var> <var>key=value [key=value ...]</var></code></td></tr>
1690 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
1691 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1692 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1693 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>ProxySet is only available in Apache HTTP Server 2.2
1694 and later.</td></tr>
1696 <p>This directive is used as an alternate method of setting any of the
1697 parameters available to Proxy balancers and workers normally done via the
1698 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive. If used
1699 within a <code><Proxy <var>balancer url|worker url</var>></code>
1700 container directive, the <var>url</var> argument is not required. As a side
1701 effect the respective balancer or worker gets created. This can be useful
1702 when doing reverse proxying via a
1703 <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> instead of a
1704 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.</p>
1706 <div class="example"><pre class="prettyprint lang-config">
1707 <Proxy balancer://hotcluster>
1708 BalancerMember http://www2.example.com:8080 loadfactor=1
1709 BalancerMember http://www3.example.com:8080 loadfactor=2
1710 ProxySet lbmethod=bytraffic
1715 <pre class="prettyprint lang-config">
1716 <Proxy http://backend>
1717 ProxySet keepalive=On
1722 <pre class="prettyprint lang-config">
1723 ProxySet balancer://foo lbmethod=bytraffic timeout=15
1727 <pre class="prettyprint lang-config">
1728 ProxySet ajp://backend:7001 timeout=15
1732 <div class="warning"><h3>Warning</h3>
1733 <p>Keep in mind that the same parameter key can have a different meaning
1734 depending whether it is applied to a balancer or a worker as shown by the two
1735 examples above regarding timeout.</p>
1740 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1741 <div class="directive-section"><h2><a name="ProxySourceAddress" id="ProxySourceAddress">ProxySourceAddress</a> <a name="proxysourceaddress" id="proxysourceaddress">Directive</a></h2>
1742 <table class="directive">
1743 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Set local IP address for outgoing proxy connections</td></tr>
1744 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxySourceAddress <var>address</var></code></td></tr>
1745 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1746 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1747 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1748 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.3.9 and later</td></tr>
1750 <p>This directive allows to set a specific local address to bind to when connecting
1751 to a backend server.</p>
1754 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1755 <div class="directive-section"><h2><a name="ProxyStatus" id="ProxyStatus">ProxyStatus</a> <a name="proxystatus" id="proxystatus">Directive</a></h2>
1756 <table class="directive">
1757 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Show Proxy LoadBalancer status in mod_status</td></tr>
1758 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyStatus Off|On|Full</code></td></tr>
1759 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyStatus Off</code></td></tr>
1760 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1761 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1762 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1763 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.2 and later</td></tr>
1765 <p>This directive determines whether or not proxy
1766 loadbalancer status data is displayed via the <code class="module"><a href="../mod/mod_status.html">mod_status</a></code>
1767 server-status page.</p>
1768 <div class="note"><h3>Note</h3>
1769 <p><strong>Full</strong> is synonymous with <strong>On</strong></p>
1774 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1775 <div class="directive-section"><h2><a name="ProxyTimeout" id="ProxyTimeout">ProxyTimeout</a> <a name="proxytimeout" id="proxytimeout">Directive</a></h2>
1776 <table class="directive">
1777 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Network timeout for proxied requests</td></tr>
1778 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyTimeout <var>seconds</var></code></td></tr>
1779 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Value of <code class="directive"><a href="../mod/core.html#timeout">Timeout</a></code></code></td></tr>
1780 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1781 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1782 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1783 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.0.31 and later</td></tr>
1785 <p>This directive allows a user to specifiy a timeout on proxy requests.
1786 This is useful when you have a slow/buggy appserver which hangs, and you
1787 would rather just return a timeout and fail gracefully instead of waiting
1788 however long it takes the server to return.</p>
1791 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1792 <div class="directive-section"><h2><a name="ProxyVia" id="ProxyVia">ProxyVia</a> <a name="proxyvia" id="proxyvia">Directive</a></h2>
1793 <table class="directive">
1794 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Information provided in the <code>Via</code> HTTP response
1795 header for proxied requests</td></tr>
1796 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyVia On|Off|Full|Block</code></td></tr>
1797 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyVia Off</code></td></tr>
1798 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1799 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1800 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1802 <p>This directive controls the use of the <code>Via:</code> HTTP
1803 header by the proxy. Its intended use is to control the flow of
1804 proxy requests along a chain of proxy servers. See <a href="http://www.ietf.org/rfc/rfc2616.txt">RFC 2616</a> (HTTP/1.1), section
1805 14.45 for an explanation of <code>Via:</code> header lines.</p>
1808 <li>If set to <code>Off</code>, which is the default, no special processing
1809 is performed. If a request or reply contains a <code>Via:</code> header,
1810 it is passed through unchanged.</li>
1812 <li>If set to <code>On</code>, each request and reply will get a
1813 <code>Via:</code> header line added for the current host.</li>
1815 <li>If set to <code>Full</code>, each generated <code>Via:</code> header
1816 line will additionally have the Apache httpd server version shown as a
1817 <code>Via:</code> comment field.</li>
1819 <li>If set to <code>Block</code>, every proxy request will have all its
1820 <code>Via:</code> header lines removed. No new <code>Via:</code> header will
1826 <div class="bottomlang">
1827 <p><span>Available Languages: </span><a href="../en/mod/mod_proxy.html" title="English"> en </a> |
1828 <a href="../fr/mod/mod_proxy.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
1829 <a href="../ja/mod/mod_proxy.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
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