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16 <p class="apache">Apache HTTP Server Version 2.3</p>
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21 <div id="page-content">
22 <div id="preamble"><h1>Apache Module mod_proxy</h1>
24 <p><span>Available Languages: </span><a href="../en/mod/mod_proxy.html" title="English"> en </a> |
25 <a href="../fr/mod/mod_proxy.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
26 <a href="../ja/mod/mod_proxy.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
28 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Multi-protocol proxy/gateway server</td></tr>
29 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
30 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>proxy_module</td></tr>
31 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_proxy.c</td></tr></table>
34 <div class="warning"><h3>Warning</h3>
35 <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
36 network and to the Internet at large.</p>
39 <p><code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> and related modules implement a
40 proxy/gateway for Apache HTTP Server, supporting a number of popular
41 protocols as well as several different load balancing algorithms.
42 Third-party modules can add support for additional protocols and
43 load balancing algorithms.</p>
45 <p>A set of modules must be loaded into the server to provide the
46 necessary features. These modules can be included statically at
47 build time or dynamically via the
48 <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code> directive).
49 The set must include:</p>
52 <li><code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, which provides basic proxy
55 <li><code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code> and one or more
56 balancer modules, if load balancing is required. (See
57 <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code> for more information.)</li>
59 <li>one or more proxy scheme, or protocol, modules:
61 <table class="bordered">
62 <tr><th>Protocol</th><th>Module</th></tr>
63 <tr><td>AJP13 (Apache JServe Protocol version
64 1.3)</td><td><code class="module"><a href="../mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code></td></tr>
66 SSL)</td><td><code class="module"><a href="../mod/mod_proxy_connect.html">mod_proxy_connect</a></code></td></tr>
67 <tr><td>FastCGI</td><td><code class="module"><a href="../mod/mod_proxy_fcgi.html">mod_proxy_fcgi</a></code></td></tr>
68 <tr><td>ftp</td><td><code class="module"><a href="../mod/mod_proxy_ftp.html">mod_proxy_ftp</a></code></td></tr>
69 <tr><td>HTTP/0.9, HTTP/1.0, and
70 HTTP/1.1</td><td><code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code></td></tr>
71 <tr><td>SCGI</td><td><code class="module"><a href="../mod/mod_proxy_scgi.html">mod_proxy_scgi</a></code></td></tr>
76 <p>In addition, extended features are provided by other modules.
77 Caching is provided by <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> and related
78 modules. The ability to contact remote servers using the SSL/TLS
79 protocol is provided by the <code>SSLProxy*</code> directives of
80 <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code>. These additional modules will need
81 to be loaded and configured to take advantage of these features.</p>
83 <div id="quickview"><h3 class="directives">Directives</h3>
85 <li><img alt="" src="../images/down.gif" /> <a href="#balancermember">BalancerMember</a></li>
86 <li><img alt="" src="../images/down.gif" /> <a href="#noproxy">NoProxy</a></li>
87 <li><img alt="" src="../images/down.gif" /> <a href="#proxy"><Proxy></a></li>
88 <li><img alt="" src="../images/down.gif" /> <a href="#proxyaddheaders">ProxyAddHeaders</a></li>
89 <li><img alt="" src="../images/down.gif" /> <a href="#proxybadheader">ProxyBadHeader</a></li>
90 <li><img alt="" src="../images/down.gif" /> <a href="#proxyblock">ProxyBlock</a></li>
91 <li><img alt="" src="../images/down.gif" /> <a href="#proxydomain">ProxyDomain</a></li>
92 <li><img alt="" src="../images/down.gif" /> <a href="#proxyerroroverride">ProxyErrorOverride</a></li>
93 <li><img alt="" src="../images/down.gif" /> <a href="#proxyiobuffersize">ProxyIOBufferSize</a></li>
94 <li><img alt="" src="../images/down.gif" /> <a href="#proxymatch"><ProxyMatch></a></li>
95 <li><img alt="" src="../images/down.gif" /> <a href="#proxymaxforwards">ProxyMaxForwards</a></li>
96 <li><img alt="" src="../images/down.gif" /> <a href="#proxypass">ProxyPass</a></li>
97 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassinterpolateenv">ProxyPassInterpolateEnv</a></li>
98 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassmatch">ProxyPassMatch</a></li>
99 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassreverse">ProxyPassReverse</a></li>
100 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassreversecookiedomain">ProxyPassReverseCookieDomain</a></li>
101 <li><img alt="" src="../images/down.gif" /> <a href="#proxypassreversecookiepath">ProxyPassReverseCookiePath</a></li>
102 <li><img alt="" src="../images/down.gif" /> <a href="#proxypreservehost">ProxyPreserveHost</a></li>
103 <li><img alt="" src="../images/down.gif" /> <a href="#proxyreceivebuffersize">ProxyReceiveBufferSize</a></li>
104 <li><img alt="" src="../images/down.gif" /> <a href="#proxyremote">ProxyRemote</a></li>
105 <li><img alt="" src="../images/down.gif" /> <a href="#proxyremotematch">ProxyRemoteMatch</a></li>
106 <li><img alt="" src="../images/down.gif" /> <a href="#proxyrequests">ProxyRequests</a></li>
107 <li><img alt="" src="../images/down.gif" /> <a href="#proxyset">ProxySet</a></li>
108 <li><img alt="" src="../images/down.gif" /> <a href="#proxystatus">ProxyStatus</a></li>
109 <li><img alt="" src="../images/down.gif" /> <a href="#proxytimeout">ProxyTimeout</a></li>
110 <li><img alt="" src="../images/down.gif" /> <a href="#proxyvia">ProxyVia</a></li>
114 <li><img alt="" src="../images/down.gif" /> <a href="#forwardreverse">Forward Proxies and Reverse
115 Proxies/Gateways</a></li>
116 <li><img alt="" src="../images/down.gif" /> <a href="#examples">Basic Examples</a></li>
117 <li><img alt="" src="../images/down.gif" /> <a href="#workers">Workers</a></li>
118 <li><img alt="" src="../images/down.gif" /> <a href="#access">Controlling access to your proxy</a></li>
119 <li><img alt="" src="../images/down.gif" /> <a href="#startup">Slow Startup</a></li>
120 <li><img alt="" src="../images/down.gif" /> <a href="#intranet">Intranet Proxy</a></li>
121 <li><img alt="" src="../images/down.gif" /> <a href="#envsettings">Protocol Adjustments</a></li>
122 <li><img alt="" src="../images/down.gif" /> <a href="#request-bodies">Request Bodies</a></li>
123 <li><img alt="" src="../images/down.gif" /> <a href="#x-headers">Reverse Proxy Request Headers</a></li>
124 </ul><h3>See also</h3>
126 <li><code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code></li>
127 <li><code class="module"><a href="../mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code></li>
128 <li><code class="module"><a href="../mod/mod_proxy_connect.html">mod_proxy_connect</a></code></li>
129 <li><code class="module"><a href="../mod/mod_proxy_fcgi.html">mod_proxy_fcgi</a></code></li>
130 <li><code class="module"><a href="../mod/mod_proxy_ftp.html">mod_proxy_ftp</a></code></li>
131 <li><code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code></li>
132 <li><code class="module"><a href="../mod/mod_proxy_scgi.html">mod_proxy_scgi</a></code></li>
133 <li><code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code></li>
134 <li><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></li>
136 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
137 <div class="section">
138 <h2><a name="forwardreverse" id="forwardreverse">Forward Proxies and Reverse
139 Proxies/Gateways</a></h2>
140 <p>Apache HTTP Server can be configured in both a <dfn>forward</dfn> and
141 <dfn>reverse</dfn> proxy (also known as <dfn>gateway</dfn>) mode.</p>
143 <p>An ordinary <dfn>forward proxy</dfn> is an intermediate
144 server that sits between the client and the <em>origin
145 server</em>. In order to get content from the origin server,
146 the client sends a request to the proxy naming the origin server
147 as the target and the proxy then requests the content from the
148 origin server and returns it to the client. The client must be
149 specially configured to use the forward proxy to access other
152 <p>A typical usage of a forward proxy is to provide Internet
153 access to internal clients that are otherwise restricted by a
154 firewall. The forward proxy can also use caching (as provided
155 by <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code>) to reduce network usage.</p>
157 <p>The forward proxy is activated using the <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> directive. Because
158 forward proxies allow clients to access arbitrary sites through
159 your server and to hide their true origin, it is essential that
160 you <a href="#access">secure your server</a> so that only
161 authorized clients can access the proxy before activating a
164 <p>A <dfn>reverse proxy</dfn> (or <dfn>gateway</dfn>), by
165 contrast, appears to the client just like an ordinary web
166 server. No special configuration on the client is necessary.
167 The client makes ordinary requests for content in the name-space
168 of the reverse proxy. The reverse proxy then decides where to
169 send those requests, and returns the content as if it was itself
172 <p>A typical usage of a reverse proxy is to provide Internet
173 users access to a server that is behind a firewall. Reverse
174 proxies can also be used to balance load among several back-end
175 servers, or to provide caching for a slower back-end server.
176 In addition, reverse proxies can be used simply to bring
177 several servers into the same URL space.</p>
179 <p>A reverse proxy is activated using the <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive or the
180 <code>[P]</code> flag to the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directive. It is
181 <strong>not</strong> necessary to turn <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> on in order to
182 configure a reverse proxy.</p>
183 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
184 <div class="section">
185 <h2><a name="examples" id="examples">Basic Examples</a></h2>
187 <p>The examples below are only a very basic idea to help you
188 get started. Please read the documentation on the individual
191 <p>In addition, if you wish to have caching enabled, consult
192 the documentation from <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code>.</p>
194 <div class="example"><h3>Reverse Proxy</h3><p><code>
195 ProxyPass /foo http://foo.example.com/bar<br />
196 ProxyPassReverse /foo http://foo.example.com/bar
199 <div class="example"><h3>Forward Proxy</h3><p><code>
200 ProxyRequests On<br />
203 <Proxy *><br />
204 <span class="indent">
205 Require host internal.example.com<br />
209 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
210 <div class="section">
211 <h2><a name="workers" id="workers">Workers</a></h2>
212 <p>The proxy manages the configuration of origin servers and their
213 communication parameters in objects called <dfn>workers</dfn>.
214 There are two built-in workers, the default forward proxy worker and the
215 default reverse proxy worker. Additional workers can be configured
218 <p>The two default workers have a fixed configuration
219 and will be used if no other worker matches the request.
220 They do not use HTTP Keep-Alive or connection pooling.
221 The TCP connections to the origin server will instead be
222 opened and closed for each request.</p>
224 <p>Explicitly configured workers are identified by their URL.
225 They are usually created and configured using
226 <code class="directive"><a href="#proxypass">ProxyPass</a></code> or
227 <code class="directive"><a href="#proxypassmatch">ProxyPassMatch</a></code> when used
228 for a reverse proxy:</p>
230 <div class="example"><p><code>
231 ProxyPass /example http://backend.example.com connectiontimeout=5 timeout=30
234 <p>This will create a worker associated with the origin server URL
235 <code>http://backend.example.com</code> and using the given timeout
236 values. When used in a forward proxy, workers are usually defined
237 via the <code class="directive"><a href="#proxyset">ProxySet</a></code> directive:</p>
239 <div class="example"><p><code>
240 ProxySet http://backend.example.com connectiontimeout=5 timeout=30
243 <p>or alternatively using <code class="directive"><a href="#proxy">Proxy</a></code>
244 and <code class="directive"><a href="#proxyset">ProxySet</a></code>:</p>
246 <div class="example"><p><code>
247 <Proxy http://backend.example.com><br />
248 <span class="indent">
249 ProxySet connectiontimeout=5 timeout=30
254 <p>Using explicitly configured workers in the forward mode is
255 not very common, because forward proxies usually communicate with many
256 different origin servers. Creating explicit workers for some of the
257 origin servers can still be useful, if they are used very often.
258 Explicitly configured workers have no concept of forward or reverse
259 proxying by themselves. They encapsulate a common concept of
260 communication with origin servers. A worker created by
261 <code class="directive"><a href="#proxypass">ProxyPass</a></code> for use in a
262 reverse proxy will be also used for forward proxy requests whenever
263 the URL to the origin server matches the worker URL and vice versa.</p>
265 <p>The URL identifying a direct worker is the URL of its
266 origin server including any path components given:</p>
268 <div class="example"><p><code>
269 ProxyPass /examples http://backend.example.com/examples<br />
270 ProxyPass /docs http://backend.example.com/docs
273 <p>This example defines two different workers, each using a separate
274 connection pool and configuration.</p>
276 <div class="warning"><h3>Worker Sharing</h3>
277 <p>Worker sharing happens if the worker URLs overlap, which occurs when
278 the URL of some worker is a leading substring of the URL of another
279 worker defined later in the configuration file. In the following example</p>
281 <div class="example"><p><code>
282 ProxyPass /apps http://backend.example.com/ timeout=60<br />
283 ProxyPass /examples http://backend.example.com/examples timeout=10
286 <p>the second worker isn't actually created. Instead the first
287 worker is used. The benefit is, that there is only one connection pool,
288 so connections are more often reused. Note that all configuration attributes
289 given explicitly for the later worker will be ignored. This will be logged
290 as a warning. In the above example the resulting timeout value
291 for the URL <code>/examples</code> will be <code>60</code> instead
292 of <code>10</code>!</p>
294 <p>If you want to avoid worker sharing, sort your worker definitions
295 by URL length, starting with the longest worker URLs. If you want to maximize
296 worker sharing use the reverse sort order. See also the related warning about
297 ordering <code class="directive"><a href="#proxypass">ProxyPass</a></code> directives.</p>
301 <p>Explicitly configured workers come in two flavors:
302 <dfn>direct workers</dfn> and <dfn>(load) balancer workers</dfn>.
303 They support many important configuration attributes which are
304 described below in the <code class="directive"><a href="#proxypass">ProxyPass</a></code>
305 directive. The same attributes can also be set using
306 <code class="directive"><a href="#proxyset">ProxySet</a></code>.</p>
308 <p>The set of options available for a direct worker
309 depends on the protocol, which is specified in the origin server URL.
310 Available protocols include <code>ajp</code>, <code>fcgi</code>,
311 <code>ftp</code>, <code>http</code> and <code>scgi</code>.</p>
313 <p>Balancer workers are virtual workers that use direct workers known
314 as their members to actually handle the requests. Each balancer can
315 have multiple members. When it handles a request, it chooses a member
316 based on the configured load balancing algorithm.</p>
318 <p>A balancer worker is created if its worker URL uses
319 <code>balancer</code> as the protocol scheme.
320 The balancer URL uniquely identifies the balancer worker.
321 Members are added to a balancer using
322 <code class="directive"><a href="#balancermember">BalancerMember</a></code>.</p>
324 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
325 <div class="section">
326 <h2><a name="access" id="access">Controlling access to your proxy</a></h2>
327 <p>You can control who can access your proxy via the <code class="directive"><a href="#proxy"><Proxy></a></code> control block as in
328 the following example:</p>
330 <div class="example"><p><code>
331 <Proxy *><br />
332 <span class="indent">
333 Require ip 192.168.0<br />
338 <p>For more information on access control directives, see
339 <code class="module"><a href="../mod/mod_authz_host.html">mod_authz_host</a></code>.</p>
341 <p>Strictly limiting access is essential if you are using a
342 forward proxy (using the <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> directive).
343 Otherwise, your server can be used by any client to access
344 arbitrary hosts while hiding his or her true identity. This is
345 dangerous both for your network and for the Internet at large.
346 When using a reverse proxy (using the <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive with
347 <code>ProxyRequests Off</code>), access control is less
348 critical because clients can only contact the hosts that you
349 have specifically configured.</p>
351 <p><strong>See Also</strong> the <a href="mod_proxy_http.html#env">Proxy-Chain-Auth</a> environment variable.</p>
353 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
354 <div class="section">
355 <h2><a name="startup" id="startup">Slow Startup</a></h2>
356 <p>If you're using the <code class="directive"><a href="#proxyblock">ProxyBlock</a></code> directive, hostnames' IP addresses are looked up
357 and cached during startup for later match test. This may take a few
358 seconds (or more) depending on the speed with which the hostname lookups
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="intranet" id="intranet">Intranet Proxy</a></h2>
363 <p>An Apache httpd proxy server situated in an intranet needs to forward
364 external requests through the company's firewall (for this, configure
365 the <code class="directive"><a href="#proxyremote">ProxyRemote</a></code> directive
366 to forward the respective <var>scheme</var> to the firewall proxy).
367 However, when it has to
368 access resources within the intranet, it can bypass the firewall when
369 accessing hosts. The <code class="directive"><a href="#noproxy">NoProxy</a></code>
370 directive is useful for specifying which hosts belong to the intranet and
371 should be accessed directly.</p>
373 <p>Users within an intranet tend to omit the local domain name from their
374 WWW requests, thus requesting "http://somehost/" instead of
375 <code>http://somehost.example.com/</code>. Some commercial proxy servers
376 let them get away with this and simply serve the request, implying a
377 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
378 a redirect response and send the client to the correct, fully qualified,
379 server address. This is the preferred method since the user's bookmark
380 files will then contain fully qualified hosts.</p>
381 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
382 <div class="section">
383 <h2><a name="envsettings" id="envsettings">Protocol Adjustments</a></h2>
384 <p>For circumstances where <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> is sending
385 requests to an origin server that doesn't properly implement
386 keepalives or HTTP/1.1, there are two <a href="../env.html">environment variables</a> that can force the
387 request to use HTTP/1.0 with no keepalive. These are set via the
388 <code class="directive"><a href="../mod/mod_env.html#setenv">SetEnv</a></code> directive.</p>
390 <p>These are the <code>force-proxy-request-1.0</code> and
391 <code>proxy-nokeepalive</code> notes.</p>
393 <div class="example"><p><code>
394 <Location /buggyappserver/><br />
395 <span class="indent">
396 ProxyPass http://buggyappserver:7001/foo/<br />
397 SetEnv force-proxy-request-1.0 1<br />
398 SetEnv proxy-nokeepalive 1<br />
403 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
404 <div class="section">
405 <h2><a name="request-bodies" id="request-bodies">Request Bodies</a></h2>
407 <p>Some request methods such as POST include a request body.
408 The HTTP protocol requires that requests which include a body
409 either use chunked transfer encoding or send a
410 <code>Content-Length</code> request header. When passing these
411 requests on to the origin server, <code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code>
412 will always attempt to send the <code>Content-Length</code>. But
413 if the body is large and the original request used chunked
414 encoding, then chunked encoding may also be used in the upstream
415 request. You can control this selection using <a href="../env.html">environment variables</a>. Setting
416 <code>proxy-sendcl</code> ensures maximum compatibility with
417 upstream servers by always sending the
418 <code>Content-Length</code>, while setting
419 <code>proxy-sendchunked</code> minimizes resource usage by using
420 chunked encoding.</p>
422 <p>Under some circumstances, the server must spool request bodies
423 to disk to satisfy the requested handling of request bodies. For
424 example, this spooling will occur if the original body was sent with
425 chunked encoding (and is large), but the administrator has
426 asked for backend requests to be sent with Content-Length or as HTTP/1.0.
427 This spooling can also occur if the request body already has a
428 Content-Length header, but the server is configured to filter incoming
431 <p><code class="directive"><a href="../mod/core.html#limitrequestbody">LimitRequestBody</a></code> only applies to
432 request bodies that the server will spool to disk</p>
434 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
435 <div class="section">
436 <h2><a name="x-headers" id="x-headers">Reverse Proxy Request Headers</a></h2>
438 <p>When acting in a reverse-proxy mode (using the <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive, for example),
439 <code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code> adds several request headers in
440 order to pass information to the origin server. These headers
444 <dt><code>X-Forwarded-For</code></dt>
445 <dd>The IP address of the client.</dd>
446 <dt><code>X-Forwarded-Host</code></dt>
447 <dd>The original host requested by the client in the <code>Host</code>
448 HTTP request header.</dd>
449 <dt><code>X-Forwarded-Server</code></dt>
450 <dd>The hostname of the proxy server.</dd>
453 <p>Be careful when using these headers on the origin server, since
454 they will contain more than one (comma-separated) value if the
455 original request already contained one of these headers. For
456 example, you can use <code>%{X-Forwarded-For}i</code> in the log
457 format string of the origin server to log the original clients IP
458 address, but you may get more than one address if the request
459 passes through several proxies.</p>
461 <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
462 other request headers.</p>
465 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
466 <div class="directive-section"><h2><a name="BalancerMember" id="BalancerMember">BalancerMember</a> <a name="balancermember" id="balancermember">Directive</a></h2>
467 <table class="directive">
468 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Add a member to a load balancing group</td></tr>
469 <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>
470 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
471 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
472 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
473 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>BalancerMember is only available in Apache HTTP Server 2.2
476 <p>This directive adds a member to a load balancing group. It could be used
477 within a <code><Proxy <var>balancer://</var>...></code> container
478 directive, and can take any of the key value pair parameters available to
479 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directives.</p>
480 <p>One additional parameter is available only to <code class="directive"><a href="#balancermember">BalancerMember</a></code> directives:
481 <var>loadfactor</var>. This is the member load factor - a number between 1
482 (default) and 100, which defines the weighted load to be applied to the
483 member in question.</p>
484 <p>The balancerurl is only needed when not in <code><Proxy <var>balancer://</var>...></code>
485 container directive. It corresponds to the url of a balancer defined in
486 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.</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="NoProxy" id="NoProxy">NoProxy</a> <a name="noproxy" id="noproxy">Directive</a></h2>
491 <table class="directive">
492 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Hosts, domains, or networks that will be connected to
494 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NoProxy <var>host</var> [<var>host</var>] ...</code></td></tr>
495 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
496 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
497 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
499 <p>This directive is only useful for Apache httpd proxy servers within
500 intranets. The <code class="directive">NoProxy</code> directive specifies a
501 list of subnets, IP addresses, hosts and/or domains, separated by
502 spaces. A request to a host which matches one or more of these is
503 always served directly, without forwarding to the configured
504 <code class="directive"><a href="#proxyremote">ProxyRemote</a></code> proxy server(s).</p>
506 <div class="example"><h3>Example</h3><p><code>
507 ProxyRemote * http://firewall.example.com:81<br />
508 NoProxy .example.com 192.168.112.0/21
511 <p>The <var>host</var> arguments to the <code class="directive">NoProxy</code>
512 directive are one of the following type list:</p>
516 <dt><var><a name="domain" id="domain">Domain</a></var></dt>
518 <p>A <dfn>Domain</dfn> is a partially qualified DNS domain name, preceded
519 by a period. It represents a list of hosts which logically belong to the
520 same DNS domain or zone (<em>i.e.</em>, the suffixes of the hostnames are
521 all ending in <var>Domain</var>).</p>
523 <div class="example"><h3>Examples</h3><p><code>
527 <p>To distinguish <var>Domain</var>s from <var><a href="#hostname">Hostname</a></var>s (both syntactically and semantically; a DNS domain can
528 have a DNS A record, too!), <var>Domain</var>s are always written with a
531 <div class="note"><h3>Note</h3>
532 <p>Domain name comparisons are done without regard to the case, and
533 <var>Domain</var>s are always assumed to be anchored in the root of the
534 DNS tree, therefore two domains <code>.ExAmple.com</code> and
535 <code>.example.com.</code> (note the trailing period) are considered
536 equal. Since a domain comparison does not involve a DNS lookup, it is much
537 more efficient than subnet comparison.</p>
541 <dt><var><a name="subnet" id="subnet">SubNet</a></var></dt>
543 <p>A <dfn>SubNet</dfn> is a partially qualified internet address in
544 numeric (dotted quad) form, optionally followed by a slash and the netmask,
545 specified as the number of significant bits in the <var>SubNet</var>. It is
546 used to represent a subnet of hosts which can be reached over a common
547 network interface. In the absence of the explicit net mask it is assumed
548 that omitted (or zero valued) trailing digits specify the mask. (In this
549 case, the netmask can only be multiples of 8 bits wide.) Examples:</p>
552 <dt><code>192.168</code> or <code>192.168.0.0</code></dt>
553 <dd>the subnet 192.168.0.0 with an implied netmask of 16 valid bits
554 (sometimes used in the netmask form <code>255.255.0.0</code>)</dd>
555 <dt><code>192.168.112.0/21</code></dt>
556 <dd>the subnet <code>192.168.112.0/21</code> with a netmask of 21
557 valid bits (also used in the form <code>255.255.248.0</code>)</dd>
560 <p>As a degenerate case, a <em>SubNet</em> with 32 valid bits is the
561 equivalent to an <var><a href="#ipadr">IPAddr</a></var>, while a <var>SubNet</var> with zero
562 valid bits (<em>e.g.</em>, 0.0.0.0/0) is the same as the constant
563 <var>_Default_</var>, matching any IP address.</p></dd>
566 <dt><var><a name="ipaddr" id="ipaddr">IPAddr</a></var></dt>
568 <p>A <dfn>IPAddr</dfn> represents a fully qualified internet address in
569 numeric (dotted quad) form. Usually, this address represents a host, but
570 there need not necessarily be a DNS domain name connected with the
572 <div class="example"><h3>Example</h3><p><code>
576 <div class="note"><h3>Note</h3>
577 <p>An <var>IPAddr</var> does not need to be resolved by the DNS system, so
578 it can result in more effective apache performance.</p>
582 <dt><var><a name="hostname" id="hostname">Hostname</a></var></dt>
584 <p>A <dfn>Hostname</dfn> is a fully qualified DNS domain name which can
585 be resolved to one or more <var><a href="#ipaddr">IPAddrs</a></var> via the
586 DNS domain name service. It represents a logical host (in contrast to
587 <var><a href="#domain">Domain</a></var>s, see above) and must be resolvable
588 to at least one <var><a href="#ipaddr">IPAddr</a></var> (or often to a list
589 of hosts with different <var><a href="#ipaddr">IPAddr</a></var>s).</p>
591 <div class="example"><h3>Examples</h3><p><code>
592 prep.ai.example.edu<br />
596 <div class="note"><h3>Note</h3>
597 <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
598 DNS lookup can be avoided. Name resolution in Apache httpd can take a remarkable
599 deal of time when the connection to the name server uses a slow PPP
601 <p><var>Hostname</var> comparisons are done without regard to the case,
602 and <var>Hostname</var>s are always assumed to be anchored in the root
603 of the DNS tree, therefore two hosts <code>WWW.ExAmple.com</code>
604 and <code>www.example.com.</code> (note the trailing period) are
605 considered equal.</p>
611 <li><a href="../dns-caveats.html">DNS Issues</a></li>
614 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
615 <div class="directive-section"><h2><a name="Proxy" id="Proxy"><Proxy></a> <a name="proxy" id="proxy">Directive</a></h2>
616 <table class="directive">
617 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Container for directives applied to proxied resources</td></tr>
618 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Proxy <var>wildcard-url</var>> ...</Proxy></code></td></tr>
619 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
620 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
621 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
623 <p>Directives placed in <code class="directive"><Proxy></code>
624 sections apply only to matching proxied content. Shell-style wildcards are
627 <p>For example, the following will allow only hosts in
628 <code>yournetwork.example.com</code> to access content via your proxy
631 <div class="example"><p><code>
632 <Proxy *><br />
633 <span class="indent">
634 Require host yournetwork.example.com<br />
639 <p>The following example will process all files in the <code>foo</code>
640 directory of <code>example.com</code> through the <code>INCLUDES</code>
641 filter when they are sent through the proxy server:</p>
643 <div class="example"><p><code>
644 <Proxy http://example.com/foo/*><br />
645 <span class="indent">
646 SetOutputFilter INCLUDES<br />
654 <li><code class="directive"><a href="#proxymatch"><ProxyMatch></a></code></li>
657 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
658 <div class="directive-section"><h2><a name="ProxyAddHeaders" id="ProxyAddHeaders">ProxyAddHeaders</a> <a name="proxyaddheaders" id="proxyaddheaders">Directive</a></h2>
659 <table class="directive">
660 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Add proxy information in X-Forwarded-* headers</td></tr>
661 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyAddHeaders Off|On</code></td></tr>
662 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyAddHeaders On</code></td></tr>
663 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
664 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
665 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
666 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.3.10 and later</td></tr>
668 <p>This directive determines whether or not proxy related information should be passed to the
669 backend server through X-Forwarded-For, X-Forwarded-Host and X-Forwarded-Server HTTP headers.</p>
670 <div class="note"><h3>Effectiveness</h3>
671 <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>
677 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
678 <div class="directive-section"><h2><a name="ProxyBadHeader" id="ProxyBadHeader">ProxyBadHeader</a> <a name="proxybadheader" id="proxybadheader">Directive</a></h2>
679 <table class="directive">
680 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines how to handle bad header lines in a
682 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyBadHeader IsError|Ignore|StartBody</code></td></tr>
683 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyBadHeader IsError</code></td></tr>
684 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
685 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
686 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
687 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.0.44 and later</td></tr>
689 <p>The <code class="directive">ProxyBadHeader</code> directive determines the
690 behaviour of <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> if it receives syntactically invalid
691 response header lines (<em>i.e.</em> containing no colon) from the origin
692 server. The following arguments are possible:</p>
695 <dt><code>IsError</code></dt>
696 <dd>Abort the request and end up with a 502 (Bad Gateway) response. This is
697 the default behaviour.</dd>
699 <dt><code>Ignore</code></dt>
700 <dd>Treat bad header lines as if they weren't sent.</dd>
702 <dt><code>StartBody</code></dt>
703 <dd>When receiving the first bad header line, finish reading the headers and
704 treat the remainder as body. This helps to work around buggy backend servers
705 which forget to insert an empty line between the headers and the body.</dd>
709 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
710 <div class="directive-section"><h2><a name="ProxyBlock" id="ProxyBlock">ProxyBlock</a> <a name="proxyblock" id="proxyblock">Directive</a></h2>
711 <table class="directive">
712 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Words, hosts, or domains that are banned from being
714 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyBlock *|<var>word</var>|<var>host</var>|<var>domain</var>
715 [<var>word</var>|<var>host</var>|<var>domain</var>] ...</code></td></tr>
716 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
717 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
718 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
720 <p>The <code class="directive">ProxyBlock</code> directive specifies a list of
721 words, hosts and/or domains, separated by spaces. HTTP, HTTPS, and
722 FTP document requests to sites whose names contain matched words,
723 hosts or domains are <em>blocked</em> by the proxy server. The proxy
724 module will also attempt to determine IP addresses of list items which
725 may be hostnames during startup, and cache them for match test as
726 well. That may slow down the startup time of the server.</p>
728 <div class="example"><h3>Example</h3><p><code>
729 ProxyBlock news.example.com auctions.example.com friends.example.com
732 <p>Note that <code>example</code> would also be sufficient to match any
735 <p>Hosts would also be matched if referenced by IP address.</p>
737 <p>Note also that</p>
739 <div class="example"><p><code>
743 <p>blocks connections to all sites.</p>
746 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
747 <div class="directive-section"><h2><a name="ProxyDomain" id="ProxyDomain">ProxyDomain</a> <a name="proxydomain" id="proxydomain">Directive</a></h2>
748 <table class="directive">
749 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Default domain name for proxied requests</td></tr>
750 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyDomain <var>Domain</var></code></td></tr>
751 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
752 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
753 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
755 <p>This directive is only useful for Apache httpd proxy servers within
756 intranets. The <code class="directive">ProxyDomain</code> directive specifies
757 the default domain which the apache proxy server will belong to. If a
758 request to a host without a domain name is encountered, a redirection
759 response to the same host with the configured <var>Domain</var> appended
760 will be generated.</p>
762 <div class="example"><h3>Example</h3><p><code>
763 ProxyRemote * http://firewall.example.com:81<br />
764 NoProxy .example.com 192.168.112.0/21<br />
765 ProxyDomain .example.com
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="ProxyErrorOverride" id="ProxyErrorOverride">ProxyErrorOverride</a> <a name="proxyerroroverride" id="proxyerroroverride">Directive</a></h2>
771 <table class="directive">
772 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Override error pages for proxied content</td></tr>
773 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyErrorOverride On|Off</code></td></tr>
774 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyErrorOverride Off</code></td></tr>
775 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
776 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
777 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
778 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.0 and later</td></tr>
780 <p>This directive is useful for reverse-proxy setups, where you want to
781 have a common look and feel on the error pages seen by the end user.
782 This also allows for included files (via
783 <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>'s SSI) to get
784 the error code and act accordingly (default behavior would display
785 the error page of the proxied server, turning this on shows the SSI
788 <p>This directive does not affect the processing of informational (1xx),
789 normal success (2xx), or redirect (3xx) responses.</p>
792 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
793 <div class="directive-section"><h2><a name="ProxyIOBufferSize" id="ProxyIOBufferSize">ProxyIOBufferSize</a> <a name="proxyiobuffersize" id="proxyiobuffersize">Directive</a></h2>
794 <table class="directive">
795 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine size of internal data throughput buffer</td></tr>
796 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyIOBufferSize <var>bytes</var></code></td></tr>
797 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyIOBufferSize 8192</code></td></tr>
798 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
799 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
800 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
802 <p>The <code class="directive">ProxyIOBufferSize</code> directive adjusts the size
803 of the internal buffer, which is used as a scratchpad for the data between
804 input and output. The size must be at least <code>512</code>.</p>
806 <p>In almost every case there's no reason to change that value.</p>
807 <p>If used with AJP this directive sets the maximum AJP packet size in
808 bytes. If you change it from the default, you must also change the
809 <code>packetSize</code> attribute of your AJP connector on the
810 Tomcat side! The attribute <code>packetSize</code> is only available
811 in Tomcat <code>5.5.20+</code> and <code>6.0.2+</code></p>
812 <p>Normally it is not necessary to change the maximum packet size.
813 Problems with the default value have been reported when sending
814 certificates or certificate chains.</p>
818 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
819 <div class="directive-section"><h2><a name="ProxyMatch" id="ProxyMatch"><ProxyMatch></a> <a name="proxymatch" id="proxymatch">Directive</a></h2>
820 <table class="directive">
821 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Container for directives applied to regular-expression-matched
822 proxied resources</td></tr>
823 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><ProxyMatch <var>regex</var>> ...</ProxyMatch></code></td></tr>
824 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
825 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
826 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
828 <p>The <code class="directive"><ProxyMatch></code> directive is
829 identical to the <code class="directive"><a href="#proxy"><Proxy></a></code> directive, except it matches URLs
830 using <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expressions</a>.</p>
834 <li><code class="directive"><a href="#proxy"><Proxy></a></code></li>
837 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
838 <div class="directive-section"><h2><a name="ProxyMaxForwards" id="ProxyMaxForwards">ProxyMaxForwards</a> <a name="proxymaxforwards" id="proxymaxforwards">Directive</a></h2>
839 <table class="directive">
840 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximium number of proxies that a request can be forwarded
842 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyMaxForwards <var>number</var></code></td></tr>
843 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyMaxForwards -1</code></td></tr>
844 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
845 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
846 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
847 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.0 and later;
848 default behaviour changed in 2.2.7/2.3</td></tr>
850 <p>The <code class="directive">ProxyMaxForwards</code> directive specifies the
851 maximum number of proxies through which a request may pass, if there's no
852 <code>Max-Forwards</code> header supplied with the request. This may
853 be set to prevent infinite proxy loops, or a DoS attack.</p>
855 <div class="example"><h3>Example</h3><p><code>
859 <p>Note that setting <code class="directive">ProxyMaxForwards</code> is a
860 violation of the HTTP/1.1 protocol (RFC2616), which forbids a Proxy
861 setting <code>Max-Forwards</code> if the Client didn't set it.
862 Earlier Apache httpd versions would always set it. A negative
863 <code class="directive">ProxyMaxForwards</code> value, including the
864 default -1, gives you protocol-compliant behaviour, but may
865 leave you open to loops.</p>
868 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
869 <div class="directive-section"><h2><a name="ProxyPass" id="ProxyPass">ProxyPass</a> <a name="proxypass" id="proxypass">Directive</a></h2>
870 <table class="directive">
871 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maps remote servers into the local server URL-space</td></tr>
872 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPass [<var>path</var>] !|<var>url</var> [<var>key=value</var>
873 <var>[key=value</var> ...]] [nocanon] [interpolate]</code></td></tr>
874 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
875 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
876 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
878 <p>This directive allows remote servers to be mapped into the
879 space of the local server; the local server does not act as a
880 proxy in the conventional sense, but appears to be a mirror of the
881 remote server. The local server is often called a <dfn>reverse
882 proxy</dfn> or <dfn>gateway</dfn>. The <var>path</var> is the name of
883 a local virtual path; <var>url</var> is a partial URL for the
884 remote server and cannot include a query string.</p>
886 <div class="warning">The <code class="directive"><a href="#proxyrequests">ProxyRequests</a></code> directive should
887 usually be set <strong>off</strong> when using
888 <code class="directive">ProxyPass</code>.</div>
890 <p>Suppose the local server has address <code>http://example.com/</code>;
893 <div class="example"><p><code>
894 <Location /mirror/foo/><br />
895 <span class="indent">
896 ProxyPass http://backend.example.com/<br />
898 </Location><br />
901 <p>will cause a local request for
902 <code>http://example.com/mirror/foo/bar</code> to be internally converted
903 into a proxy request to <code>http://backend.example.com/bar</code>.</p>
905 <p>The following alternative syntax is possible, however carries a
906 performance penalty when present in large numbers:</p>
908 <div class="example"><p><code>
909 ProxyPass /mirror/foo/ http://backend.example.com/
912 <div class="warning">
913 <p>If the first argument ends with a trailing <strong>/</strong>, the second
914 argument should also end with a trailing <strong>/</strong> and vice
915 versa. Otherwise the resulting requests to the backend may miss some
916 needed slashes and do not deliver the expected results.
920 <p>The <code>!</code> directive is useful in situations where you don't want
921 to reverse-proxy a subdirectory, <em>e.g.</em></p>
923 <div class="example"><p><code>
924 <Location /mirror/foo/><br />
925 <span class="indent">
926 ProxyPass http://backend.example.com/<br />
928 </Location><br />
929 <Location /mirror/foo/i><br />
930 <span class="indent">
933 </Location><br />
936 <div class="example"><p><code>
937 ProxyPass /mirror/foo/i !<br />
938 ProxyPass /mirror/foo http://backend.example.com
941 <p>will proxy all requests to <code>/mirror/foo</code> to
942 <code>backend.example.com</code> <em>except</em> requests made to
943 <code>/mirror/foo/i</code>.</p>
945 <div class="warning"><h3>Ordering ProxyPass Directives</h3>
946 <p>The configured <code class="directive"><a href="#proxypass">ProxyPass</a></code>
947 and <code class="directive"><a href="#proxypassmatch">ProxyPassMatch</a></code>
948 rules are checked in the order of configuration. The first rule that
949 matches wins. So usually you should sort conflicting
950 <code class="directive"><a href="#proxypass">ProxyPass</a></code> rules starting with the
951 longest URLs first. Otherwise later rules for longer URLS will be hidden
952 by any earlier rule which uses a leading substring of the URL. Note that
953 there is some relation with worker sharing. In contrast, only one
954 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive can be placed
955 in a <code class="directive"><a href="../mod/core.html#location">Location</a></code> block, and the most
956 specific location will take precedence.</p>
958 <p>For the same reasons exclusions must come <em>before</em> the
959 general <code class="directive">ProxyPass</code> directives.</p>
963 <p>In Apache HTTP Server 2.1 and later, mod_proxy supports pooled
964 connections to a backend server. Connections created on demand
965 can be retained in a pool for future use. Limits on the pool size
966 and other settings can be coded on
967 the <code class="directive">ProxyPass</code> directive
968 using <code>key=value</code> parameters, described in the table
971 <p>By default, mod_proxy will allow and retain the maximum number of
972 connections that could be used simultaneously by that web server child
973 process. Use the <code>max</code> parameter to reduce the number from
974 the default. Use the <code>ttl</code> parameter to set an optional
975 time to live; connections which have been unused for at least
976 <code>ttl</code> seconds will be closed. <code>ttl</code> can be used
977 to avoid using a connection which is subject to closing because of the
978 backend server's keep-alive timeout.</p>
980 <p>The pool of connections is maintained per web server child
981 process, and <code>max</code> and other settings are not coordinated
982 among all child processes, except when only one child process is allowed
983 by configuration or MPM design.</p>
985 <div class="example"><h3>Example</h3><p><code>
986 ProxyPass /example http://backend.example.com max=20 ttl=120 retry=300
989 <table class="bordered"><tr><th>BalancerMember parameters</th></tr></table>
991 <tr><th>Parameter</th>
993 <th>Description</th></tr>
996 <td>Minimum number of connection pool entries, unrelated to the
997 actual number of connections. This only needs to be modified from the
998 default for special circumstances where heap memory associated with the
999 backend connections should be preallocated or retained.</td></tr>
1002 <td>Maximum number of connections that will be allowed to the
1003 backend server. The default for this limit is the number of threads
1004 per process in the active MPM. In the Prefork MPM, this is always 1,
1005 while with other MPMs it is controlled by the
1006 <code class="directive">ThreadsPerChild</code> directive.</td></tr>
1009 <td>Retained connection pool entries above this limit are freed
1010 during certain operations if they have been unused for longer than
1011 the time to live, controlled by the <code>ttl</code> parameter. If
1012 the connection pool entry has an associated connection, it will be
1013 closed. This only needs to be modified from the default for special
1014 circumstances where connection pool entries and any associated
1015 connections which have exceeded the time to live need to be freed or
1016 closed more aggressively.</td></tr>
1017 <tr><td>acquire</td>
1019 <td>If set this will be the maximum time to wait for a free
1020 connection in the connection pool, in milliseconds. If there are no free
1021 connections in the pool the Apache httpd will return <code>SERVER_BUSY</code>
1022 status to the client.
1024 <tr><td>connectiontimeout</td>
1026 <td>Connect timeout in seconds.
1027 The number of seconds Apache httpd waits for the creation of a connection to
1028 the backend to complete. By adding a postfix of ms the timeout can be
1029 also set in milliseconds.
1031 <tr><td>disablereuse</td>
1033 <td>This parameter should be used when you want to force mod_proxy
1034 to immediately close a connection to the backend after being used, and
1035 thus, disable its persistent connection and pool for that backend.
1036 This helps in various situations where a firewall between Apache
1038 the backend server (regardless of protocol) tends to silently
1039 drop connections or when backends themselves may be under round-
1040 robin DNS. To disable connection pooling reuse,
1041 set this property value to <code>On</code>.
1043 <tr><td>flushpackets</td>
1045 <td>Determines whether the proxy module will auto-flush the output
1046 brigade after each "chunk" of data. 'off' means that it will flush
1047 only when needed, 'on' means after each chunk is sent and
1048 'auto' means poll/wait for a period of time and flush if
1049 no input has been received for 'flushwait' milliseconds.
1050 Currently this is in effect only for AJP.
1052 <tr><td>flushwait</td>
1054 <td>The time to wait for additional input, in milliseconds, before
1055 flushing the output brigade if 'flushpackets' is 'auto'.
1057 <tr><td>iobuffersize</td>
1059 <td>Adjusts the size of the internal scratchpad IO buffer. This allows you
1060 to override the <code class="directive">ProxyIOBufferSize</code> for a specific worker.
1061 This must be at least 512 or set to 0 for the system default of 8192.
1063 <tr><td>keepalive</td>
1065 <td><p>This parameter should be used when you have a firewall between your
1066 Apache httpd and the backend server, who tend to drop inactive connections.
1067 This flag will tell the Operating System to send <code>KEEP_ALIVE</code>
1068 messages on inactive connections and thus prevent the firewall to drop the connection.
1069 To enable keepalive set this property value to <code>On</code>. </p>
1070 <p>The frequency of initial and subsequent TCP keepalive probes
1071 depends on global OS settings, and may be as high as 2 hours. To be useful,
1072 the frequency configured in the OS must be smaller than the threshold used
1073 by the firewall.</p>
1077 <td>Sets the load balancer cluster set that the worker is a member
1078 of. The load balancer will try all members of a lower numbered
1079 lbset before trying higher numbered ones.
1083 <td>Ping property tells the webserver to "test" the connection to
1084 the backend before forwarding the request. For AJP, it causes
1085 <code class="module"><a href="../mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code>to send a <code>CPING</code>
1086 request on the ajp13 connection (implemented on Tomcat 3.3.2+, 4.1.28+
1087 and 5.0.13+). For HTTP, it causes <code class="module"><a href="../mod/mod_proxy_http.html">mod_proxy_http</a></code>
1088 to send a <code>100-Continue</code> to the backend (only valid for
1089 HTTP/1.1 - for non HTTP/1.1 backends, this property has no
1090 effect). In both cases the parameter is the delay in seconds to wait
1092 This feature has been added to avoid problems with hung and
1094 This will increase the network traffic during the normal operation
1095 which could be an issue, but it will lower the
1096 traffic in case some of the cluster nodes are down or busy.
1097 By adding a postfix of ms the delay can be also set in
1100 <tr><td>receivebuffersize</td>
1102 <td>Adjusts the size of the explicit (TCP/IP) network buffer size for
1103 proxied connections. This allows you to override the
1104 <code class="directive">ProxyReceiveBufferSize</code> for a specific worker.
1105 This must be at least 512 or set to 0 for the system default.
1107 <tr><td>redirect</td>
1109 <td>Redirection Route of the worker. This value is usually
1110 set dynamically to enable safe removal of the node from
1111 the cluster. If set all requests without session id will be
1112 redirected to the BalancerMember that has route parametar
1113 equal as this value.
1117 <td>Connection pool worker retry timeout in seconds.
1118 If the connection pool worker to the backend server is in the error state,
1119 Apache httpd will not forward any requests to that server until the timeout
1120 expires. This enables to shut down the backend server for maintenance,
1121 and bring it back online later. A value of 0 means always retry workers
1122 in an error state with no timeout.
1126 <td>Route of the worker when used inside load balancer.
1127 The route is a value appended to session id.
1131 <td>Single letter value defining the initial status of
1132 this worker: 'D' is disabled, 'S' is stopped, 'I' is ignore-errors,
1133 'H' is hot-standby and 'E' is in an error state. Status
1134 can be set (which is the default) by prepending with '+' or
1135 cleared by prepending with '-'.
1136 Thus, a setting of 'S-E' sets this worker to Stopped and
1137 clears the in-error flag.
1139 <tr><td>timeout</td>
1140 <td><code class="directive"><a href="#proxytimeout">ProxyTimeout</a></code></td>
1141 <td>Connection timeout in seconds.
1142 The number of seconds Apache httpd waits for data sent by / to the backend.
1146 <td>Time to live for inactive connections and associated connection
1147 pool entries, in seconds. Once reaching this limit, a
1148 connection will not be used again; it will be closed at some
1154 <p>If the Proxy directive scheme starts with the
1155 <code>balancer://</code> (eg: <code>balancer://cluster/</code>,
1156 any path information is ignored) then a virtual worker that does not really
1157 communicate with the backend server will be created. Instead it is responsible
1158 for the management of several "real" workers. In that case the special set of
1159 parameters can be add to this virtual worker. See <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code>
1160 for more information about how the balancer works.
1162 <table class="bordered"><tr><th>Balancer parameters</th></tr></table>
1164 <tr><th>Parameter</th>
1166 <th>Description</th></tr>
1167 <tr><td>lbmethod</td>
1169 <td>Balancer load-balance method. Select the load-balancing scheduler
1170 method to use. Either <code>byrequests</code>, to perform weighted
1171 request counting, <code>bytraffic</code>, to perform weighted
1172 traffic byte count balancing, or <code>bybusyness</code>, to perform
1173 pending request balancing. Default is <code>byrequests</code>.
1175 <tr><td>maxattempts</td>
1176 <td>One less than the number of workers, or 1 with a single worker.</td>
1177 <td>Maximum number of failover attempts before giving up.
1179 <tr><td>nofailover</td>
1181 <td>If set to <code>On</code> the session will break if the worker is in
1182 error state or disabled. Set this value to On if backend servers do not
1183 support session replication.
1185 <tr><td>stickysession</td>
1187 <td>Balancer sticky session name. The value is usually set to something
1188 like <code>JSESSIONID</code> or <code>PHPSESSIONID</code>,
1189 and it depends on the backend application server that support sessions.
1190 If the backend application server uses different name for cookies
1191 and url encoded id (like servlet containers) use | to to separate them.
1192 The first part is for the cookie the second for the path.
1194 <tr><td>scolonpathdelim</td>
1196 <td>If set to <code>On</code> the semi-colon character ';' will be
1197 used as an additional sticky session path deliminator/separator. This
1198 is mainly used to emulate mod_jk's behavior when dealing with paths such
1199 as <code>JSESSIONID=6736bcf34;foo=aabfa</code>
1201 <tr><td>timeout</td>
1203 <td>Balancer timeout in seconds. If set this will be the maximum time
1204 to wait for a free worker. Default is not to wait.
1206 <tr><td>failonstatus</td>
1208 <td>A single or comma-separated list of HTTP status codes. If set this will
1209 force the worker into error state when the backend returns any status code
1210 in the list. Worker recovery behaves the same as other worker errors.
1213 <td><auto></td>
1214 <td>The protective nonce used in the <code>balancer-manager</code> application page.
1215 The default is to use an automatically determined UUID-based
1216 nonce, to provide for further protection for the page. If set,
1217 then the nonce is set to that value. A setting of <code>None</code>
1218 disables all nonce checking.
1219 <div class="note"><h3>Note</h3>
1220 <p>In addition to the nonce, the <code>balancer-manager</code> page
1221 should be protected via an ACL.</p>
1226 <td>Number of additional BalancerMembers to allow to be added
1227 to this balancer in addition to those defined at configuration.
1231 <p>A sample balancer setup</p>
1232 <div class="example"><p><code>
1233 ProxyPass /special-area http://special.example.com smax=5 max=10<br />
1234 ProxyPass / balancer://mycluster/ stickysession=JSESSIONID|jsessionid nofailover=On<br />
1235 <Proxy balancer://mycluster><br />
1236 <span class="indent">
1237 BalancerMember ajp://1.2.3.4:8009<br />
1238 BalancerMember ajp://1.2.3.5:8009 loadfactor=20<br />
1239 # Less powerful server, don't send as many requests there,<br />
1240 BalancerMember ajp://1.2.3.6:8009 loadfactor=5<br />
1245 <p>Setting up a hot-standby, that will only be used if no other
1246 members are available</p>
1247 <div class="example"><p><code>
1248 ProxyPass / balancer://hotcluster/ <br />
1249 <Proxy balancer://hotcluster><br />
1250 <span class="indent">
1251 BalancerMember ajp://1.2.3.4:8009 loadfactor=1<br />
1252 BalancerMember ajp://1.2.3.5:8009 loadfactor=2<br />
1253 # The below is the hot standby<br />
1254 BalancerMember ajp://1.2.3.6:8009 status=+H<br />
1255 ProxySet lbmethod=bytraffic
1260 <p>Normally, mod_proxy will canonicalise ProxyPassed URLs.
1261 But this may be incompatible with some backends, particularly those
1262 that make use of <var>PATH_INFO</var>. The optional <var>nocanon</var>
1263 keyword suppresses this, and passes the URL path "raw" to the
1264 backend. Note that may affect the security of your backend, as it
1265 removes the normal limited protection against URL-based attacks
1266 provided by the proxy.</p>
1268 <p>The optional <var>interpolate</var> keyword (available in
1269 httpd 2.2.9 and later), in combination with
1270 <code class="directive">ProxyPassInterpolateEnv</code> causes the ProxyPass
1271 to interpolate environment variables, using the syntax
1272 <var>${VARNAME}</var>. Note that many of the standard CGI-derived
1273 environment variables will not exist when this interpolation happens,
1274 so you may still have to resort to <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
1275 for complex rules.</p>
1277 <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
1278 directory is obtained from the <code class="directive"><a href="../mod/core.html#location"><Location></a></code>. The same will occur inside a
1279 <code class="directive"><a href="../mod/core.html#locationmatch"><LocationMatch></a></code> section,
1280 however ProxyPass does not interpret the regexp as such, so it is necessary
1281 to use <code class="directive">ProxyPassMatch</code> in this situation instead.</p>
1283 <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>
1285 <p>If you require a more flexible reverse-proxy configuration, see the
1286 <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directive with the
1287 <code>[P]</code> flag.</p>
1291 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1292 <div class="directive-section"><h2><a name="ProxyPassInterpolateEnv" id="ProxyPassInterpolateEnv">ProxyPassInterpolateEnv</a> <a name="proxypassinterpolateenv" id="proxypassinterpolateenv">Directive</a></h2>
1293 <table class="directive">
1294 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable Environment Variable interpolation in Reverse Proxy configurations</td></tr>
1295 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassInterpolateEnv On|Off</code></td></tr>
1296 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyPassInterpolateEnv Off</code></td></tr>
1297 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1298 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1299 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1300 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in httpd 2.2.9 and later</td></tr>
1302 <p>This directive, together with the <var>interpolate</var> argument to
1303 <code class="directive">ProxyPass</code>, <code class="directive">ProxyPassReverse</code>,
1304 <code class="directive">ProxyPassReverseCookieDomain</code> and
1305 <code class="directive">ProxyPassReverseCookiePath</code>
1306 enables reverse proxies to be dynamically
1307 configured using environment variables, which may be set by
1308 another module such as <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>.
1309 It affects the <code class="directive">ProxyPass</code>,
1310 <code class="directive">ProxyPassReverse</code>,
1311 <code class="directive">ProxyPassReverseCookieDomain</code>, and
1312 <code class="directive">ProxyPassReverseCookiePath</code> directives,
1313 and causes them to substitute the value of an environment
1314 variable <code>varname</code> for the string <code>${varname}</code>
1315 in configuration directives.</p>
1316 <p>Keep this turned off (for server performance) unless you need it!</p>
1319 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1320 <div class="directive-section"><h2><a name="ProxyPassMatch" id="ProxyPassMatch">ProxyPassMatch</a> <a name="proxypassmatch" id="proxypassmatch">Directive</a></h2>
1321 <table class="directive">
1322 <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>
1323 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassMatch [<var>regex</var>] !|<var>url</var> [<var>key=value</var>
1324 <var>[key=value</var> ...]]</code></td></tr>
1325 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1326 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1327 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1329 <p>This directive is equivalent to <code class="directive"><a href="#proxypass">ProxyPass</a></code>,
1330 but makes use of regular expressions, instead of simple prefix matching. The
1331 supplied regular expression is matched against the <var>url</var>, and if it
1332 matches, the server will substitute any parenthesized matches into the given
1333 string and use it as a new <var>url</var>.</p>
1335 <p>Suppose the local server has address <code>http://example.com/</code>;
1338 <div class="example"><p><code>
1339 ProxyPassMatch ^(/.*\.gif)$ http://backend.example.com$1
1342 <p>will cause a local request for
1343 <code>http://example.com/foo/bar.gif</code> to be internally converted
1344 into a proxy request to <code>http://backend.example.com/foo/bar.gif</code>.</p>
1345 <div class="note"><h3>Note</h3>
1346 <p>The URL argument must be parsable as a URL <em>before</em> regexp
1347 substitutions (as well as after). This limits the matches you can use.
1348 For instance, if we had used</p>
1349 <div class="example"><p><code>
1350 ProxyPassMatch ^(/.*\.gif)$ http://backend.example.com:8000$1
1352 <p>in our previous example, it would fail with a syntax error
1353 at server startup. This is a bug (PR 46665 in the ASF bugzilla),
1354 and the workaround is to reformulate the match:</p>
1355 <div class="example"><p><code>
1356 ProxyPassMatch ^/(.*\.gif)$ http://backend.example.com:8000/$1
1359 <p>The <code>!</code> directive is useful in situations where you don't want
1360 to reverse-proxy a subdirectory.</p>
1362 <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
1363 regexp is obtained from the <code class="directive"><a href="../mod/core.html#locationmatch"><LocationMatch></a></code>.</p>
1365 <p>If you require a more flexible reverse-proxy configuration, see the
1366 <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directive with the
1367 <code>[P]</code> flag.</p>
1370 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1371 <div class="directive-section"><h2><a name="ProxyPassReverse" id="ProxyPassReverse">ProxyPassReverse</a> <a name="proxypassreverse" id="proxypassreverse">Directive</a></h2>
1372 <table class="directive">
1373 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Adjusts the URL in HTTP response headers sent from a reverse
1374 proxied server</td></tr>
1375 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassReverse [<var>path</var>] <var>url</var>
1376 [<var>interpolate</var>]</code></td></tr>
1377 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1378 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1379 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1381 <p>This directive lets Apache httpd adjust the URL in the <code>Location</code>,
1382 <code>Content-Location</code> and <code>URI</code> headers on HTTP
1383 redirect responses. This is essential when Apache httpd is used as a
1384 reverse proxy (or gateway) to avoid by-passing the reverse proxy
1385 because of HTTP redirects on the backend servers which stay behind
1386 the reverse proxy.</p>
1388 <p>Only the HTTP response headers specifically mentioned above
1389 will be rewritten. Apache httpd will not rewrite other response
1390 headers, nor will it rewrite URL references inside HTML pages.
1391 This means that if the proxied content contains absolute URL
1392 references, they will by-pass the proxy. A third-party module
1393 that will look inside the HTML and rewrite URL references is Nick
1394 Kew's <a href="http://apache.webthing.com/mod_proxy_html/">mod_proxy_html</a>.</p>
1396 <p><var>path</var> is the name of a local virtual path. <var>url</var> is a
1397 partial URL for the remote server - the same way they are used for the
1398 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.</p>
1400 <p>For example, suppose the local server has address
1401 <code>http://example.com/</code>; then</p>
1403 <div class="example"><p><code>
1404 ProxyPass /mirror/foo/ http://backend.example.com/<br />
1405 ProxyPassReverse /mirror/foo/ http://backend.example.com/<br />
1406 ProxyPassReverseCookieDomain backend.example.com public.example.com<br />
1407 ProxyPassReverseCookiePath / /mirror/foo/
1410 <p>will not only cause a local request for the
1411 <code>http://example.com/mirror/foo/bar</code> to be internally converted
1412 into a proxy request to <code>http://backend.example.com/bar</code>
1413 (the functionality <code>ProxyPass</code> provides here). It also takes care
1414 of redirects the server <code>backend.example.com</code> sends: when
1415 <code>http://backend.example.com/bar</code> is redirected by him to
1416 <code>http://backend.example.com/quux</code> Apache httpd adjusts this to
1417 <code>http://example.com/mirror/foo/quux</code> before forwarding the HTTP
1418 redirect response to the client. Note that the hostname used for
1419 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>
1421 <p>Note that this <code class="directive">ProxyPassReverse</code> directive can
1422 also be used in conjunction with the proxy pass-through feature
1423 (<code>RewriteRule ... [P]</code>) from <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
1424 because it doesn't depend on a corresponding <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.</p>
1426 <p>The optional <var>interpolate</var> keyword (available in
1427 httpd 2.2.9 and later), used together with
1428 <code class="directive">ProxyPassInterpolateEnv</code>, enables interpolation
1429 of environment variables specified using the format <var>${VARNAME}</var>.
1432 <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
1433 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
1434 intended, as ProxyPassReverse will interpret the regexp literally as a
1435 path; if needed in this situation, specify the ProxyPassReverse outside
1436 the section, or in a separate <code class="directive"><a href="../mod/core.html#location"><Location></a></code> section.</p>
1438 <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>
1441 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1442 <div class="directive-section"><h2><a name="ProxyPassReverseCookieDomain" id="ProxyPassReverseCookieDomain">ProxyPassReverseCookieDomain</a> <a name="proxypassreversecookiedomain" id="proxypassreversecookiedomain">Directive</a></h2>
1443 <table class="directive">
1444 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Adjusts the Domain string in Set-Cookie headers from a reverse-
1445 proxied server</td></tr>
1446 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassReverseCookieDomain <var>internal-domain</var>
1447 <var>public-domain</var> [<var>interpolate</var>]</code></td></tr>
1448 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1449 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1450 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1452 <p>Usage is basically similar to
1453 <code class="directive"><a href="#proxypassreverse">ProxyPassReverse</a></code>, but instead of
1454 rewriting headers that are a URL, this rewrites the <code>domain</code>
1455 string in <code>Set-Cookie</code> headers.</p>
1458 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1459 <div class="directive-section"><h2><a name="ProxyPassReverseCookiePath" id="ProxyPassReverseCookiePath">ProxyPassReverseCookiePath</a> <a name="proxypassreversecookiepath" id="proxypassreversecookiepath">Directive</a></h2>
1460 <table class="directive">
1461 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Adjusts the Path string in Set-Cookie headers from a reverse-
1462 proxied server</td></tr>
1463 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPassReverseCookiePath <var>internal-path</var>
1464 <var>public-path</var> [<var>interpolate</var>]</code></td></tr>
1465 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1466 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1467 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1469 <p>Usage is basically similar to
1470 <code class="directive"><a href="#proxypassreverse">ProxyPassReverse</a></code>, but instead of
1471 rewriting headers that are a URL, this rewrites the <code>path</code>
1472 string in <code>Set-Cookie</code> headers.</p>
1475 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1476 <div class="directive-section"><h2><a name="ProxyPreserveHost" id="ProxyPreserveHost">ProxyPreserveHost</a> <a name="proxypreservehost" id="proxypreservehost">Directive</a></h2>
1477 <table class="directive">
1478 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use incoming Host HTTP request header for proxy
1480 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyPreserveHost On|Off</code></td></tr>
1481 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyPreserveHost Off</code></td></tr>
1482 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1483 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1484 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1485 <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
1486 context in 2.3.3 and later.</td></tr>
1488 <p>When enabled, this option will pass the Host: line from the incoming
1489 request to the proxied host, instead of the hostname specified in the
1490 <code class="directive">ProxyPass</code> line.</p>
1492 <p>This option should normally be turned <code>Off</code>. It is mostly
1493 useful in special configurations like proxied mass name-based virtual
1494 hosting, where the original Host header needs to be evaluated by the
1498 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1499 <div class="directive-section"><h2><a name="ProxyReceiveBufferSize" id="ProxyReceiveBufferSize">ProxyReceiveBufferSize</a> <a name="proxyreceivebuffersize" id="proxyreceivebuffersize">Directive</a></h2>
1500 <table class="directive">
1501 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Network buffer size for proxied HTTP and FTP
1502 connections</td></tr>
1503 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyReceiveBufferSize <var>bytes</var></code></td></tr>
1504 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyReceiveBufferSize 0</code></td></tr>
1505 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1506 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1507 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1509 <p>The <code class="directive">ProxyReceiveBufferSize</code> directive specifies an
1510 explicit (TCP/IP) network buffer size for proxied HTTP and FTP connections,
1511 for increased throughput. It has to be greater than <code>512</code> or set
1512 to <code>0</code> to indicate that the system's default buffer size should
1515 <div class="example"><h3>Example</h3><p><code>
1516 ProxyReceiveBufferSize 2048
1520 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1521 <div class="directive-section"><h2><a name="ProxyRemote" id="ProxyRemote">ProxyRemote</a> <a name="proxyremote" id="proxyremote">Directive</a></h2>
1522 <table class="directive">
1523 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Remote proxy used to handle certain requests</td></tr>
1524 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyRemote <var>match</var> <var>remote-server</var></code></td></tr>
1525 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1526 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1527 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1529 <p>This defines remote proxies to this proxy. <var>match</var> is either the
1530 name of a URL-scheme that the remote server supports, or a partial URL
1531 for which the remote server should be used, or <code>*</code> to indicate
1532 the server should be contacted for all requests. <var>remote-server</var> is
1533 a partial URL for the remote server. Syntax:</p>
1535 <div class="example"><p><code>
1536 <dfn>remote-server</dfn> =
1537 <var>scheme</var>://<var>hostname</var>[:<var>port</var>]
1540 <p><var>scheme</var> is effectively the protocol that should be used to
1541 communicate with the remote server; only <code>http</code> and <code>https</code>
1542 are supported by this module. When using <code>https</code>, the requests
1543 are forwarded through the remote proxy using the HTTP CONNECT method.</p>
1545 <div class="example"><h3>Example</h3><p><code>
1546 ProxyRemote http://goodguys.example.com/ http://mirrorguys.example.com:8000<br />
1547 ProxyRemote * http://cleverproxy.localdomain<br />
1548 ProxyRemote ftp http://ftpproxy.mydomain:8080
1551 <p>In the last example, the proxy will forward FTP requests, encapsulated
1552 as yet another HTTP proxy request, to another proxy which can handle
1555 <p>This option also supports reverse proxy configuration - a backend
1556 webserver can be embedded within a virtualhost URL space even if that
1557 server is hidden by another forward proxy.</p>
1560 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1561 <div class="directive-section"><h2><a name="ProxyRemoteMatch" id="ProxyRemoteMatch">ProxyRemoteMatch</a> <a name="proxyremotematch" id="proxyremotematch">Directive</a></h2>
1562 <table class="directive">
1563 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Remote proxy used to handle requests matched by regular
1564 expressions</td></tr>
1565 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyRemoteMatch <var>regex</var> <var>remote-server</var></code></td></tr>
1566 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1567 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1568 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1570 <p>The <code class="directive">ProxyRemoteMatch</code> is identical to the
1571 <code class="directive"><a href="#proxyremote">ProxyRemote</a></code> directive, except the
1572 first argument is a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>
1573 match against the requested URL.</p>
1576 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1577 <div class="directive-section"><h2><a name="ProxyRequests" id="ProxyRequests">ProxyRequests</a> <a name="proxyrequests" id="proxyrequests">Directive</a></h2>
1578 <table class="directive">
1579 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables forward (standard) proxy requests</td></tr>
1580 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyRequests On|Off</code></td></tr>
1581 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyRequests Off</code></td></tr>
1582 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1583 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1584 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1586 <p>This allows or prevents Apache httpd from functioning as a forward proxy
1587 server. (Setting ProxyRequests to <code>Off</code> does not disable use of
1588 the <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.)</p>
1590 <p>In a typical reverse proxy or gateway configuration, this
1591 option should be set to
1592 <code>Off</code>.</p>
1594 <p>In order to get the functionality of proxying HTTP or FTP sites, you
1595 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>
1596 (or both) present in the server.</p>
1598 <div class="warning"><h3>Warning</h3>
1599 <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
1600 both to your network and to the Internet at large.</p>
1605 <li><a href="#forwardreverse">Forward and Reverse Proxies/Gateways</a></li>
1608 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1609 <div class="directive-section"><h2><a name="ProxySet" id="ProxySet">ProxySet</a> <a name="proxyset" id="proxyset">Directive</a></h2>
1610 <table class="directive">
1611 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Set various Proxy balancer or member parameters</td></tr>
1612 <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>
1613 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
1614 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1615 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1616 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>ProxySet is only available in Apache HTTP Server 2.2
1617 and later.</td></tr>
1619 <p>This directive is used as an alternate method of setting any of the
1620 parameters available to Proxy balancers and workers normally done via the
1621 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive. If used
1622 within a <code><Proxy <var>balancer url|worker url</var>></code>
1623 container directive, the <var>url</var> argument is not required. As a side
1624 effect the respective balancer or worker gets created. This can be useful
1625 when doing reverse proxying via a
1626 <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> instead of a
1627 <code class="directive"><a href="#proxypass">ProxyPass</a></code> directive.</p>
1629 <div class="example"><p><code>
1630 <Proxy balancer://hotcluster><br />
1631 <span class="indent">
1632 BalancerMember http://www2.example.com:8080 loadfactor=1<br />
1633 BalancerMember http://www3.example.com:8080 loadfactor=2<br />
1634 ProxySet lbmethod=bytraffic<br />
1639 <div class="example"><p><code>
1640 <Proxy http://backend><br />
1641 <span class="indent">
1642 ProxySet keepalive=On<br />
1647 <div class="example"><p><code>
1648 ProxySet balancer://foo lbmethod=bytraffic timeout=15
1651 <div class="example"><p><code>
1652 ProxySet ajp://backend:7001 timeout=15
1655 <div class="warning"><h3>Warning</h3>
1656 <p>Keep in mind that the same parameter key can have a different meaning
1657 depending whether it is applied to a balancer or a worker as shown by the two
1658 examples above regarding timeout.</p>
1663 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1664 <div class="directive-section"><h2><a name="ProxyStatus" id="ProxyStatus">ProxyStatus</a> <a name="proxystatus" id="proxystatus">Directive</a></h2>
1665 <table class="directive">
1666 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Show Proxy LoadBalancer status in mod_status</td></tr>
1667 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyStatus Off|On|Full</code></td></tr>
1668 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyStatus Off</code></td></tr>
1669 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1670 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1671 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1672 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.2 and later</td></tr>
1674 <p>This directive determines whether or not proxy
1675 loadbalancer status data is displayed via the <code class="module"><a href="../mod/mod_status.html">mod_status</a></code>
1676 server-status page.</p>
1677 <div class="note"><h3>Note</h3>
1678 <p><strong>Full</strong> is synonymous with <strong>On</strong></p>
1683 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1684 <div class="directive-section"><h2><a name="ProxyTimeout" id="ProxyTimeout">ProxyTimeout</a> <a name="proxytimeout" id="proxytimeout">Directive</a></h2>
1685 <table class="directive">
1686 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Network timeout for proxied requests</td></tr>
1687 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyTimeout <var>seconds</var></code></td></tr>
1688 <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>
1689 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1690 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1691 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1692 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.0.31 and later</td></tr>
1694 <p>This directive allows a user to specifiy a timeout on proxy requests.
1695 This is useful when you have a slow/buggy appserver which hangs, and you
1696 would rather just return a timeout and fail gracefully instead of waiting
1697 however long it takes the server to return.</p>
1700 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1701 <div class="directive-section"><h2><a name="ProxyVia" id="ProxyVia">ProxyVia</a> <a name="proxyvia" id="proxyvia">Directive</a></h2>
1702 <table class="directive">
1703 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Information provided in the <code>Via</code> HTTP response
1704 header for proxied requests</td></tr>
1705 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProxyVia On|Off|Full|Block</code></td></tr>
1706 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProxyVia Off</code></td></tr>
1707 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1708 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
1709 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_proxy</td></tr>
1711 <p>This directive controls the use of the <code>Via:</code> HTTP
1712 header by the proxy. Its intended use is to control the flow of
1713 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
1714 14.45 for an explanation of <code>Via:</code> header lines.</p>
1717 <li>If set to <code>Off</code>, which is the default, no special processing
1718 is performed. If a request or reply contains a <code>Via:</code> header,
1719 it is passed through unchanged.</li>
1721 <li>If set to <code>On</code>, each request and reply will get a
1722 <code>Via:</code> header line added for the current host.</li>
1724 <li>If set to <code>Full</code>, each generated <code>Via:</code> header
1725 line will additionally have the Apache httpd server version shown as a
1726 <code>Via:</code> comment field.</li>
1728 <li>If set to <code>Block</code>, every proxy request will have all its
1729 <code>Via:</code> header lines removed. No new <code>Via:</code> header will
1735 <div class="bottomlang">
1736 <p><span>Available Languages: </span><a href="../en/mod/mod_proxy.html" title="English"> en </a> |
1737 <a href="../fr/mod/mod_proxy.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
1738 <a href="../ja/mod/mod_proxy.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
1739 </div><div id="footer">
1740 <p class="apache">Copyright 2011 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
1741 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div>