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<head>
<title>Apache module mod_proxy</title>
</head>
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<blockquote><strong>Warning:</strong>
This document has been updated to take into account changes
made in the 2.0 version of the Apache HTTP Server. Some of the
information may still be inaccurate, please use it
with care.
</blockquote>
<h1 align="center">Apache module mod_proxy</h1>
<p>This module provides for an <strong>HTTP 1.1</strong> proxy / gateway
server.</p>
<p><a
href="module-dict.html#Status"
rel="Help"
><strong>Status:</strong></a> Extension
<br>
<a
href="module-dict.html#SourceFile"
rel="Help"
><strong>Source File:</strong></a> mod_proxy.c
<br>
<a
href="module-dict.html#ModuleIdentifier"
rel="Help"
><strong>Module Identifier:</strong></a> proxy_module
<br>
<a
href="module-dict.html#Compatibility"
rel="Help"
><strong>Compatibility:</strong></a> Available in Apache 1.1 and later.
</p>
<h2>Summary</h2>
This module implements a proxy/gateway for Apache. It implements
proxying capability for
<code>FTP</code>,
<code>CONNECT</code> (for SSL),
<code>HTTP/0.9</code>,
<code>HTTP/1.0</code>, and
<code>HTTP/1.1</code>.
The module can be configured to connect to other proxy modules for these
and other protocols.
<p>This module was experimental in Apache 1.1.x. Improvements and bugfixes
were made in Apache v1.2.x and Apache v1.3.x, then the module underwent a major
overhaul for Apache v2.0. The protocol support was upgraded to HTTP/1.1,
and filter support was enabled.
<p>Please note that the <strong>caching</strong> function present in mod_proxy up to Apache
v1.3.x has been <strong>removed</strong> from mod_proxy and will be incorporated
into a new module, mod_cache.
<p>
<h2>Directives</h2>
<ul>
<li><a href="#allowconnect">AllowCONNECT</a>
<li><a href="#noproxy">NoProxy</a>
<li><a href="#proxyblock">ProxyBlock</a>
<li><a href="#proxydomain">ProxyDomain</a>
<li><a href="#proxyerroroverride">ProxyErrorOverride</a>
<li><a href="#proxymaxforwards">ProxyMaxForwards</a>
<li><a href="#proxypass">ProxyPass</a>
<li><a href="#proxypassreverse">ProxyPassReverse</a>
<li><a href="#proxypreservehost">ProxyPreserveHost</a>
<li><a href="#proxyreceivebuffersize">ProxyReceiveBufferSize</a>
<li><a href="#proxyremote">ProxyRemote</a>
<li><a href="#proxyrequests">ProxyRequests</a>
<li><a href="#proxytimeout">ProxyTimeout</a>
<li><a href="#proxyvia">ProxyVia</a>
</ul>
<h2><a name="configs">Common configuration topics</a></h2>
<ul>
<li><a href="#forwardreverse">Forward and Reverse Proxies</a>
<li><a href="#access">Controlling access to your proxy</a>
<li><a href="#shortname">Using Netscape hostname shortcuts</a>
<li><a href="#mimetypes">Why doesn't file type <em>xxx</em> download via FTP?</a>
<li><a href="#type">How can I force an FTP ASCII download of File <em>xxx</em>?</a></li>
<li><a href="#percent2fhack">How can I access FTP files outside of my home directory?</a></li>
<li><a href="#ftppass">How can I hide the FTP cleartext password in my browser's URL line?</a></li>
<li><a href="#startup">Why does Apache start more slowly when using the
proxy module?</a>
<!--<li><a href="#socks">Can I use the Apache proxy module with my SOCKS proxy?</a>-->
<li><a href="#intranet">What other functions are useful for an intranet proxy server?</a>
</ul>
<h2><a name="forwardreverse">Forward and Reverse Proxies</a></h2>
Apache can be configured in both a <em>forward</em> and <em>reverse</em>
proxy configuration.
<p>A <em>forward proxy</em> is an intermediate system that enables a browser to connect to a
remote network to which it normally does not have access. A forward proxy
can also be used to cache data, reducing load on the networks between the
forward proxy and the remote webserver.
<p>Apache's mod_proxy can be figured to
behave like a forward proxy using the <a href="#proxyremote">ProxyRemote</a>
directive. In addition, caching of data can be achieved by configuring
Apache mod_cache. Other dedicated forward proxy packages include
<a href="http://www.squid.org">Squid</a>.
<p>A <em>reverse proxy</em> is a webserver system that is capable of serving webpages
sourced from other webservers - in addition to webpages on disk or generated
dynamically by CGI - making these pages look like they originated at the
reverse proxy.
<p>When configured with the mod_cache module the reverse
proxy can act as a cache for slower backend webservers. The reverse proxy
can also enable advanced URL strategies and management techniques, allowing
webpages served using different webserver systems or architectures to
coexist inside the same URL space. Reverse proxy systems are also ideal for
implementing centralised logging websites with many or diverse website
backends. Complex multi-tier webserver systems can be constructed using an
Apache mod_proxy frontend and any number of backend webservers.
<p>The reverse proxy is configured using the
<a href="#proxypass">ProxyPass</a> and <a
href="#proxypassreverse">ProxyPassReverse</a> directives. Caching can be
enabled using mod_cache as with the forward proxy.
<h2><a name="access">Controlling access to your proxy</a></h2>
You can control who can access your proxy via the normal &lt;Directory&gt;
control block using the following example:<p>
<pre>
&lt;Directory proxy:*&gt;
Order Deny,Allow
Deny from [machines you'd like *not* to allow by IP address or name]
Allow from [machines you'd like to allow by IP address or name]
&lt;/Directory&gt;
</pre><p>
A &lt;Files&gt; block will also work, and is the only method known to work
for all possible URLs in Apache versions earlier than 1.2b10.<p>
When configuring a reverse proxy, access control takes on the attributes of
the normal server <directory> configuration.
<!--<h2><a name="shortname">Using Netscape hostname shortcuts</a></h2>
There is an optional patch to the proxy module to allow Netscape-like
hostname shortcuts to be used. It's available from the
<a href="http://www.apache.org/dist/contrib/patches/1.2/netscapehost.patch"
><samp>contrib/patches/1.2</samp></a> directory on the Apache Web
site.<p>-->
<h2><a name="mimetypes">Why doesn't file type <em>xxx</em> download via FTP?</a></h2>
You probably don't have that particular file type defined as
<em>application/octet-stream</em> in your proxy's mime.types configuration
file. A useful line can be<p>
<pre>
application/octet-stream bin dms lha lzh exe class tgz taz
</pre>
<h2><a name="type">How can I force an FTP ASCII download of File <em>xxx</em>?</a></h2>
In the rare situation where you must download a specific file using the FTP
<strong>ASCII</strong> transfer method (while the default transfer is in
<strong>binary</strong> mode), you can override mod_proxy's default by
suffixing the request with <samp>;type=a</samp> to force an ASCII transfer.
(FTP Directory listings are always executed in ASCII mode, however.)</p>
<h2><a name="percent2fhack">How can I access FTP files outside of my home directory?</a></h2>
<p>
An FTP URI is interpreted relative to the home directory of
the user who is logging in. Alas, to reach higher directory
levels you cannot use /../, as the dots are interpreted by the
browser and not actually sent to the FTP server. To address
this problem, the so called "Squid %2f hack" was implemented in
the Apache FTP proxy; it is is a solution which is also used by
other popular proxy servers like the
<a href="http://www.squid-cache.org/">Squid Proxy Cache</a>.
By prepending /%2f to the path of your request, you can make
such a proxy change the FTP starting directory to / (instead
of the home directory). <br />
<b>Example:</b> To retrieve the file <code>/etc/motd</code>,
you would use the URL <blockquote>
<code>ftp://<em>user@host</em>/%2f/etc/motd</code></blockquote>
</p>
<h2><a id="ftppass" name="ftppass">How can I hide the FTP cleartext password in my browser's URL line?</a></h2>
<p>
To log in to an FTP server by username and password, Apache
uses different strategies.
In absense of a user name and password in the URL altogether,
Apache sends an anomymous login to the FTP server, i.e.,
<blockquote><code>
user: anonymous<br />
password: apache_proxy@
</code></blockquote>
This works for all popular FTP servers which are configured for
anonymous access.<br>
For a personal login with a specific username, you can embed
the user name into the URL, like in:
<code>ftp://<em>username@host</em>/myfile</code>. If the FTP server
asks for a password when given this username (which it should),
then Apache will reply with a [401 Authorization required] response,
which causes the Browser to pop up the username/password dialog.
Upon entering the password, the connection attempt is retried,
and if successful, the requested resource is presented.
The advantage of this procedure is that your browser does not
display the password in cleartext (which it would if you had used
<code>ftp://<em>username:password@host</em>/myfile</code> in
the first place).
<br />
<b>Note</b> that the password which is transmitted in such a way
is not encrypted on its way. It travels between your browser and
the Apache proxy server in a base64-encoded cleartext string, and
between the Apache proxy and the FTP server as plaintext. You should
therefore think twice before accessing your FTP server via HTTP
(or before accessing your personal files via FTP at all!) When
using unsecure channels, an eavesdropper might intercept your
password on its way.
</p>
<h2><a name="startup">Why does Apache start more slowly when using the
proxy module?</a></h2>
If you're using the <code>ProxyBlock</code>
directive, hostnames' IP addresses are looked up and cached during
startup for later match test. This may take a few seconds (or more)
depending on the speed with which the hostname lookups occur.<p>
<!--<h2><a name="socks">Can I use the Apache proxy module with my SOCKS proxy?</a></h2>
Yes. Just build Apache with the rule <code>SOCKS4=yes</code> in your
<em>Configuration</em> file, and follow the instructions there. SOCKS5
capability can be added in a similar way (there's no <code>SOCKS5</code>
rule yet), so use the <code>EXTRA_LDFLAGS</code> definition, or build Apache
normally and run it with the <em>runsocks</em> wrapper provided with SOCKS5,
if your OS supports dynamically linked libraries.<p>
Some users have reported problems when using SOCKS version 4.2 on Solaris.
The problem was solved by upgrading to SOCKS 4.3.<p>
Remember that you'll also have to grant access to your Apache proxy machine by
permitting connections on the appropriate ports in your SOCKS daemon's
configuration.<p>
-->
<h2><a name="intranet">What other functions are useful for an intranet proxy server?</a></h2>
<p>An Apache proxy server situated in an intranet needs to forward external
requests through the company's firewall. However, when it has to access
resources within the intranet, it can bypass the firewall when accessing
hosts. The <a href="#noproxy">NoProxy</a> directive is useful for specifying
which hosts belong to the intranet and should be accessed directly.</p>
<p>Users within an intranet tend to omit the local domain name from their
WWW requests, thus requesting "http://somehost/" instead of
"http://somehost.my.dom.ain/". Some commercial proxy servers let them get
away with this and simply serve the request, implying a configured
local domain. When the <a href="#proxydomain">ProxyDomain</a> directive
is used and the server is <a href="#proxyrequests">configured for
proxy service</a>, Apache can return a redirect response and send the client
to the correct, fully qualified, server address. This is the preferred method
since the user's bookmark files will then contain fully qualified hosts.</p>
<hr>
<h2><a name="proxyrequests">ProxyPreserveHost</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyPreserveHost on|off<br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <code>ProxyPreserveHost Off</code><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyPreserveHost is only available in
Apache 2.0.31 and later.<p>
When enabled, this option will pass the Host: line from the incoming request to
the proxied host, instead of the hostname specified in the proxypass line.
</p>
<p>This option should normally be turned 'off'.</p>
<hr>
<h2><a name="proxyrequests">ProxyRequests</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyRequests on|off<br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <code>ProxyRequests Off</code><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyRequests is only available in
Apache 1.1 and later.<p>
This allows or prevents Apache from functioning as a forward proxy
server. (Setting ProxyRequests to 'off' does not disable use of the <a
href="#proxypass">ProxyPass</a> directive.)
<p>In a typical reverse proxy configuration, this option should be set to
'off'.
<hr>
<h2><a name="proxyremote">ProxyRemote</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyRemote <em>match remote-server</em><br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>None</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyRemote is only available in
Apache 1.1 and later.<p>
This defines remote proxies to this proxy. <em>match</em> is either the
name of a URL-scheme that the remote server supports, or a partial URL
for which the remote server should be used, or '*' to indicate the
server should be contacted for all requests. <em>remote-server</em> is a
partial URL for the remote server. Syntax:
<pre>
remote-server = protocol://hostname[:port]
</pre>
<em>protocol</em> is the protocol that should be used to communicate
with the remote server; only "http" is supported by this module.
<p>
Example:
<pre>
ProxyRemote http://goodguys.com/ http://mirrorguys.com:8000
ProxyRemote * http://cleversite.com
ProxyRemote ftp http://ftpproxy.mydomain.com:8080
</pre>
In the last example, the proxy will forward FTP requests, encapsulated
as yet another HTTP proxy request, to another proxy which can handle
them.
<p>This option also supports reverse proxy configuration - a backend webserver
can be embedded within a virtualhost URL space even if that server is hidden
by another forward proxy.
<hr>
<h2><a name="proxypass">ProxyPass</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyPass <em>path url</em><br>
or: ProxyPass <em>url</em> when placed in a &lt;location&gt; directive <em>(Apache 2.0 only)</em><br>
or: ProxyPass <em>path !</em> to exclude a path from being proxied.
<br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>None</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyPass is only available in
Apache 1.1 and later.<p>
This directive allows remote servers to be mapped into the space of the local
server; the local server does not act as a proxy in the conventional sense,
but appears to be a mirror of the remote server. <em>path</em> is the name of
a local virtual path; <em>url</em> is a partial URL for the remote server.
<p>
Suppose the local server has address <samp>http://wibble.org/</samp>; then
<pre>
ProxyPass /mirror/foo/ http://foo.com/
</pre>
will cause a local request for the
&lt;<samp>http://wibble.org/mirror/foo/bar</samp>&gt; to be
internally converted into a proxy request to
&lt;<samp>http://foo.com/bar</samp>&gt;.
<p>
The ! directive is useful in situations where you don't want to reverse-proxy
a subdirectory. eg.
<pre>
ProxyPass /mirror/foo/i !
ProxyPass /mirror/foo http://foo.com
</pre>
will proxy all requests to /mirror/foo to foo.com EXCEPT requests made to /mirror/foo/i
<b>NB: order is important. you need to put the exclusions BEFORE the general proxypass directive</b>
</p>
<hr>
<h2><a name="proxypassreverse">ProxyPassReverse</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyPassReverse <em>path url</em><br>
or: ProxyPassReverse <em>url</em> when placed in a &lt;location&gt; directive <em>(Apache 2.0 only)</em><br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>None</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyPassReverse is only available in
Apache 1.3b6 and later.<p>
This directive lets Apache adjust the URL in the <tt>Location</tt>,
<tt>Content-Location</tt> and <tt>URI</tt> headers on
HTTP redirect responses. This is essential when Apache is used as
a reverse proxy to avoid by-passing the reverse proxy because of HTTP
redirects on the backend servers which stay behind the reverse proxy.
<p>
<em>path</em> is the name of a local virtual path.<br>
<em>url</em> is a partial URL for the remote server - the same way they are
used for the <tt>ProxyPass</tt> directive.
<p>
Example:<br>
Suppose the local server has address <samp>http://wibble.org/</samp>; then
<pre>
ProxyPass /mirror/foo/ http://foo.com/
ProxyPassReverse /mirror/foo/ http://foo.com/
</pre>
will not only cause a local request for the
&lt;<samp>http://wibble.org/mirror/foo/bar</samp>&gt; to be internally
converted into a proxy request to &lt;<samp>http://foo.com/bar</samp>&gt; (the
functionality <samp>ProxyPass</samp> provides here). It also takes care of
redirects the server foo.com sends: when <samp>http://foo.com/bar</samp> is
redirected by him to <samp>http://foo.com/quux</samp> Apache adjusts this to
<samp>http://wibble.org/mirror/foo/quux</samp> before forwarding the HTTP
redirect response to the client.
<p>
Note that this <samp>ProxyPassReverse</samp> directive can also be used in
conjunction with the proxy pass-through feature ("<samp>RewriteRule ...
[P]</samp>") from
<a
href="mod_rewrite.html#RewriteRule"
><tt>mod_rewrite</tt></a> because its doesn't depend on a corresponding
<samp>ProxyPass</samp> directive.
<hr>
<h2><a name="allowconnect">AllowCONNECT</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> AllowCONNECT <em>port</em>
[<em>port</em>] ...<br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em><samp>AllowCONNECT</samp> 443 563</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> <samp>AllowCONNECT</samp> is only
available in Apache 1.3.2 and later.<p>
The <samp>AllowCONNECT</samp> directive specifies a list of port numbers
to which the proxy <samp>CONNECT</samp> method may connect.
Today's browsers use this method when a <em>https</em> connection
is requested and proxy tunneling over <em>http</em> is in effect.<br>
By default, only the default https port (443) and the default
snews port (563) are enabled. Use the <samp>AllowCONNECT</samp>
directive to overrride this default and allow connections to the
listed ports only.
<hr>
<h2><a name="proxyblock">ProxyBlock</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyBlock *|<em>word|host|domain</em>
[<em>word|host|domain</em>] ...<br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>None</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyBlock is only available in
Apache 1.2 and later.<p>
The ProxyBlock directive specifies a list of words, hosts and/or domains,
separated by spaces. HTTP, HTTPS, and FTP document requests to sites whose
names contain matched words, hosts or domains are <em>blocked</em> by the
proxy server. The proxy module will also attempt to determine IP addresses of
list items which may be hostnames during startup, and cache them for match
test as well. Example:
<pre>
ProxyBlock joes-garage.com some-host.co.uk rocky.wotsamattau.edu
</pre>
'rocky.wotsamattau.edu' would also be matched if referenced by IP address.<p>
Note that 'wotsamattau' would also be sufficient to match 'wotsamattau.edu'.<p>
Note also that
<pre>
ProxyBlock *
</pre>
blocks connections to all sites.
<hr>
<h2><a name="proxyreceivebuffersize">ProxyReceiveBufferSize</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyReceiveBufferSize <em>bytes</em><br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>None</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyReceiveBufferSize is only available in
Apache 1.3 and later.<p>
The ProxyReceiveBufferSize directive specifies an explicit network buffer size
for outgoing HTTP and FTP connections, for increased throughput. It has to be
greater than 512 or set to 0 to indicate that the system's default buffer size
should be used.
<p>
Example:
<pre>
ProxyReceiveBufferSize 2048
</pre>
<hr>
<h2><a name="proxymaxforwards">ProxyMaxForwards</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyMaxForwards <em>bytes</em><br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>10</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyMaxForwards is only available in
Apache 2.0 and later.<p>
The ProxyMaxForwards directive specifies the maximum number of proxies
through which a request may pass. This is set to prevent infinite proxy
loops, or a DoS attack.
<p>
Example:
<pre>
ProxyMaxForwards 10
</pre>
<hr>
<h2><a name="noproxy">NoProxy</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> NoProxy
<a href="#domain"><em>Domain</em></a>|<a
href="#subnet"><em>SubNet</em></a>|<a
href="#ipaddr"><em>IpAddr</em></a>|<a
href="#hostname"><em>Hostname</em></a>
[<a href="#domain"><em>Domain</em></a>|<a
href="#subnet"><em>SubNet</em></a>|<a
href="#ipaddr"><em>IpAddr</em></a>|<a
href="#hostname"><em>Hostname</em></a>] ...<br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>None</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> NoProxy is only available in
Apache 1.3 and later.<p>
This directive is only useful for Apache proxy servers within intranets.
The NoProxy directive specifies a list of subnets, IP addresses, hosts
and/or domains, separated by spaces. A request to a host which matches
one or more of these is always served directly, without forwarding to
the configured ProxyRemote proxy server(s).
<p>
Example:
<pre>
ProxyRemote * http://firewall.mycompany.com:81
NoProxy .mycompany.com 192.168.112.0/21
</pre>
The arguments to the NoProxy directive are one of the following type list:
<dl>
<!-- ===================== Domain ======================= -->
<a name="domain">
<dt><em>Domain</em></a>
<dd>A <em>Domain</em> is a partially qualified DNS domain name, preceded
by a period.
It represents a list of hosts which logically belong to the same DNS
domain or zone (<em>i.e.</em>, the suffixes of the hostnames are all ending in
<em>Domain</em>).<br>
Examples: <samp>.com</samp> <samp>.apache.org.</samp><br>
To distinguish <em>Domain</em>s from <a href="#hostname"><em>Hostname</em></a>s (both
syntactically and semantically; a DNS domain can have a DNS A record,
too!), <em>Domain</em>s are always written
with a leading period.<br>
Note: Domain name comparisons are done without regard to the case,
and <em>Domain</em>s are always assumed to be anchored in the root
of the DNS tree, therefore two domains <samp>.MyDomain.com</samp> and
<samp>.mydomain.com.</samp> (note the trailing period) are
considered equal. Since a domain comparison does not involve a DNS
lookup, it is much more efficient than subnet comparison.
<!-- ===================== SubNet ======================= -->
<a name="subnet">
<dt><em>SubNet</em></a>
<dd>A <em>SubNet</em> is a partially qualified internet address in
numeric (dotted quad) form, optionally followed by a slash and the
netmask, specified as the number of significant bits in the
<em>SubNet</em>. It is used to represent a subnet of hosts which can
be reached over a common network interface. In the absence of the
explicit net mask it is assumed that omitted (or zero valued)
trailing digits specify the mask. (In this case, the netmask can
only be multiples of 8 bits wide.)<br>
Examples:
<dl>
<dt><samp>192.168</samp> or <samp>192.168.0.0</samp>
<dd>the subnet 192.168.0.0 with an implied netmask of 16 valid bits
(sometimes used in the netmask form <samp>255.255.0.0</samp>)
<dt><samp>192.168.112.0/21</samp>
<dd>the subnet <samp>192.168.112.0/21</samp> with a netmask of 21
valid bits (also used in the form 255.255.248.0)
</dl>
As a degenerate case, a <em>SubNet</em> with 32 valid bits is the
equivalent to an <em>IPAddr</em>, while a <em>SubNet</em> with zero
valid bits (<em>e.g.</em>, 0.0.0.0/0) is the same as the constant
<em>_Default_</em>, matching any IP address.
<!-- ===================== IPAddr ======================= -->
<a name="ipaddr">
<dt><em>IPAddr</em></a>
<dd>A <em>IPAddr</em> represents a fully qualified internet address in
numeric (dotted quad) form. Usually, this address represents a
host, but there need not necessarily be a DNS domain name
connected with the address.<br>
Example: 192.168.123.7<br>
Note: An <em>IPAddr</em> does not need to be resolved by the DNS
system, so it can result in more effective apache performance.
<p><strong>See Also:</strong>
<a href="../dns-caveats.html">DNS Issues</a></p>
<!-- ===================== Hostname ======================= -->
<a name="hostname">
<dt><em>Hostname</em></a>
<dd>A <em>Hostname</em> is a fully qualified DNS domain name which can
be resolved to one or more <a
href="#ipaddr"><em>IPAddrs</em></a> via the DNS domain name service.
It represents a logical host (in contrast to
<a href="#domain"><em>Domain</em></a>s, see
above) and must be resolvable to at least one <a
href="#ipaddr"><em>IPAddr</em></a> (or often to a list of hosts
with different <a href="#ipaddr"><em>IPAddr</em></a>'s).<br>
Examples: <samp>prep.ai.mit.edu</samp>
<samp>www.apache.org.</samp><br>
Note: In many situations, it is more effective to specify an
<a href="#ipaddr"><em>IPAddr</em></a> in place of a
<em>Hostname</em> since a DNS lookup
can be avoided. Name resolution in Apache can take a remarkable deal
of time when the connection to the name server uses a slow PPP
link.<br>
Note: <em>Hostname</em> comparisons are done without regard to the case,
and <em>Hostname</em>s are always assumed to be anchored in the root
of the DNS tree, therefore two hosts <samp>WWW.MyDomain.com</samp>
and <samp>www.mydomain.com.</samp> (note the trailing period) are
considered equal.<br>
<p><strong>See Also:</strong>
<a href="../dns-caveats.html">DNS Issues</a></p>
</dl>
<hr>
<h2><a name="proxytimeout">ProxyTimeout</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyTimeout <em>n</em> seconds<br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>server default timeout</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyDomain is only available in
Apache 2.0.31 and later.<p>
<p>This directive allows a user to specifiy a timeout on proxy requests.
This is usefull when you have a slow/buggy appserver which hangs,
and you would rather just return a timeout and fail gracefully instead
of waiting however long it takes the server to return
</p>
<hr>
<h2><a name="proxydomain">ProxyDomain</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyDomain <em>Domain</em><br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>None</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyDomain is only available in
Apache 1.3 and later.<p>
This directive is only useful for Apache proxy servers within intranets.
The ProxyDomain directive specifies the default domain which the apache
proxy server will belong to. If a request to a host without a domain name
is encountered, a redirection response to the same host
with the configured <em>Domain</em> appended will be generated.
<p>
Example:
<pre>
ProxyRemote * http://firewall.mycompany.com:81
NoProxy .mycompany.com 192.168.112.0/21
ProxyDomain .mycompany.com
</pre>
<hr>
<h2><a name="proxyvia">ProxyVia</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyVia on|off|full|block<br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>ProxyVia off</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyVia is only available in
Apache 1.3.2 and later.<p>
This directive controls the use of the <samp>Via:</samp> HTTP header
by the proxy. Its intended use is to control the flow of of proxy
requests along a chain of proxy servers.
See RFC2068 (HTTP/1.1) for an explanation of <samp>Via:</samp> header lines.<ul>
<li>If set to <em>off</em>, which is the default, no special
processing is performed. If a request or reply contains a <samp>Via:</samp> header,
it is passed through unchanged.
<li>If set to <em>on</em>, each request and reply will get a <samp>Via:</samp> header
line added for the current host.
<li>If set to <em>full</em>, each generated <samp>Via:</samp> header line will
additionally have the Apache server version shown as a <samp>Via:</samp> comment field.
<li>If set to <em>block</em>, every proxy request will have all its
<samp>Via:</samp> header lines removed. No new <samp>Via:</samp> header will be generated.
</ul>
<hr>
<h2><a name="proxyerroroverride">ProxyErrorOverride</a> directive</h2>
<a
href="directive-dict.html#Syntax"
REL="Help"
><strong>Syntax:</strong></a> ProxyErrorOverride<em>on</em><br>
<a
href="directive-dict.html#Default"
REL="Help"
><strong>Default:</strong></a> <em>off</em><br>
<a
href="directive-dict.html#Context"
REL="Help"
><strong>Context:</strong></a> server config, virtual host<br>
<a
href="directive-dict.html#Override"
REL="Help"
><strong>Override:</strong></a> <em>Not applicable</em><br>
<a
href="directive-dict.html#Status"
REL="Help"
><strong>Status:</strong></a> Base<br>
<a
href="directive-dict.html#Module"
REL="Help"
><strong>Module:</strong></a> mod_proxy<br>
<a
href="directive-dict.html#Compatibility"
REL="Help"
><strong>Compatibility:</strong></a> ProxyErrorOverride
Apache 2.0 and later.<p>
This directive is useful for reverse-proxy setups, where you want to
have a common look and feel on the error pages seen by the end user.
This also allows for included files (via mod_include's SSI) to get
the error code and act accordingly (default behavior would display
the error page of the proxied server, turning this on shows the SSI
Error message).
<p>
<!--#include virtual="footer.html" -->
</body>
</html>
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