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<H1>Apache module mod_proxy</h1>

This module is contained in the <code>mod_proxy.c</code> file for Apache 1.1.x,
or the <code>modules/proxy/libproxy.a</code> library for Apache 1.2, and
is not compiled in by default. It provides for a caching proxy server.
It is only available in Apache 1.1 and later. Common configuration
questions are addressed <a href="#configs">here</a>.

<h3>Note:</h3>
<p>This module was experimental in Apache 1.1.x. As of Apache 1.2, mod_proxy
stability is <i>greatly</i> improved.<p>

<h2>Summary</h2>

This module implements a proxy/cache for Apache. It implements
proxying capability for
<code>FTP</code>,
<code>CONNECT</code> (for SSL),
<code>HTTP/0.9</code>, and
<code>HTTP/1.0</code>.
The module can be configured to connect to other proxy modules for these
and other protocols.

<h2>Directives</h2>
<ul>
<li><a href="#proxyrequests">ProxyRequests</a>
<li><a href="#proxyremote">ProxyRemote</a>
<li><a href="#proxypass">ProxyPass</a>
<li><a href="#proxyblock">ProxyBlock</a>
<li><a href="#cacheroot">CacheRoot</a>
<li><a href="#cachesize">CacheSize</a>
<li><a href="#cachemaxexpire">CacheMaxExpire</a>
<li><a href="#cachedefaultexpire">CacheDefaultExpire</a>
<li><a href="#cachelastmodifiedfactor">CacheLastModifiedFactor</a>
<li><a href="#cachegcinterval">CacheGcInterval</a>
<li><a href="#cachedirlevels">CacheDirLevels</a>
<li><a href="#cachedirlength">CacheDirLength</a>
<li><a href="#nocache">NoCache</a>
</ul>

<hr>

<A name="proxyrequests"><h2>ProxyRequests</h2></A>
<strong>Syntax:</strong> ProxyRequests <em>on/off</em><br>
<strong>Default:</strong> <code>ProxyRequests Off</code><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> ProxyRequest is only available in
Apache 1.1 and later.<p>

This allows or prevents Apache from functioning as a proxy
server. Setting ProxyRequests to 'off' does not disable use of the <a
href="#proxypass">ProxyPass</a> directive.

<A name="proxyremote"><h2>ProxyRemote</h2></A>
<strong>Syntax:</strong> ProxyRemote <em>&lt;match&gt; &lt;remote-server&gt;</em><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> ProxyRemote is only available in
Apache 1.1 and later.<p>

This defines remote proxies to this proxy. &lt;match&gt; 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. &lt;remote-server&gt; is a
partial URL for the remote server. Syntax:

<pre>
  &lt;remote-server&gt; = &lt;protocol&gt;://&lt;hostname&gt;[:port]
</pre>

&lt;protocol&gt; is the protocol that should be used to communicate
with the remote server; only "http" is supported by this module.

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.

<A name="proxypass"><h2>ProxyPass</h2></A>
<strong>Syntax:</strong> ProxyPass <em>&lt;path&gt; &lt;url&gt;</em><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> 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. &lt;path&gt; is the name of
a local virtual path; &lt;url&gt; is a partial URL for the remote server.

Suppose the local server has address http://wibble.org; then
<pre>
   ProxyPass /mirror/foo http://foo.com
</pre>
Will cause a local request for the http://wibble.org/mirror/foo/bar to be
internally converted into a proxy request to http://foo.com/bar

<A name="proxyblock"><h2>ProxyBlock</h2></A>
<strong>Syntax:</strong> ProxyBlock <em>&lt;word/host/domain list&gt;</em><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> 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 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.

<A name="cacheroot"><h2>CacheRoot</h2></A>
<strong>Syntax:</strong> CacheRoot <em>&lt;directory&gt;</em><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> CacheRoot is only available in
Apache 1.1 and later.<p>

Sets the name of the directory to contain cache files; this must be
writable
by the httpd server.

<A name="cachesize"><h2>CacheSize</h2></A>
<strong>Syntax:</strong> CacheSize <em>&lt;size&gt;</em><br>
<strong>Default:</strong> <code>CacheSize 5</code><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> CacheSize is only available in
Apache 1.1 and later.<p>

Sets the desired space usage of the cache, in Kb (1024 byte units). Although
usage may grow above this setting, the garbage collection will delete files
until the usage is at or below this setting.

<A name="cachegcinterval"><h2>CacheGcInterval</h2></A>
<strong>Syntax:</strong> CacheGcInterval <em>&lt;time&gt;</em><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> CacheGcinterval is only available in
Apache 1.1 and later.<p>

Check the cache every &lt;time&gt; hours, and delete files if the space
usage is greater than that set by CacheSize.

<A name="cachemaxexpire"><h2>CacheMaxExpire</h2></A>
<strong>Syntax:</strong> CacheMaxExpire <em>&lt;time&gt;</em><br>
<strong>Default:</strong> </code>CacheMaxExpire 24</code><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> CacheMaxExpire is only available in
Apache 1.1 and later.<p>

Cachable HTTP documents will be retained for at most &lt;time&gt; hours without
checking the origin server. Thus documents can be at most &lt;time&gt;
hours out of date. This restriction is enforced even if an expiry date
was supplied with the document.

<A name="cachelastmodifiedfactor"><h2>CacheLastModifiedFactor</h2></A>
<strong>Syntax:</strong> CacheLastModifiedFactor <em>&lt;factor&gt;</em><br>
<strong>Default:</strong> </code>CacheLastModifiedFactor 0.1</code><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> CacheLastModifiedFactor is only available in
Apache 1.1 and later.<p>

If the origin HTTP server did not supply an expiry date for the
document, then estimate one using the formula
<pre>
  expiry-period = time-since-last-modification * &lt;factor&gt;
</pre>
For example, if the document was last modified 10 hours ago, and
&lt;factor&gt; is 0.1, then the expiry period will be set to 10*0.1 = 1 hour.

<p>If the expiry-period would be longer than that set by CacheMaxExpire,
then the latter takes precedence.

<A name="cachedirlevels"><h2>CacheDirLevels</h2></A>
<strong>Syntax:</strong> CacheDirLevels <em>&lt;levels&gt;</em><br>
<strong>Default:</strong> </code>CacheDirLevels 3</code><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> CacheDirLevels is only available in
Apache 1.1 and later.<p>

CacheDirLevels sets the number of levels of subdirectories in the cache.
Cached data will be saved this many directory levels below CacheRoot.

<A name="cachedirlength"><h2>CacheDirLength</h2></A>
<strong>Syntax:</strong> CacheDirLength <em>&lt;length&gt;</em><br>
<strong>Default:</strong> </code>CacheDirLength 1</code><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> CacheDirLength is only available in
Apache 1.1 and later.<p>

CacheDirLength sets the number of characters in proxy cache subdirectory names.

<A name="cachedefaultexpire"><h2>CacheDefaultExpire</h2></A>
<strong>Syntax:</strong> CacheDefaultExpire <em>&lt;time&gt;</em><br>
<strong>Default:</strong> </code>CacheDefaultExpire 1</code><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> CacheDefaultExpire is only available in
Apache 1.1 and later.<p>

If the document is fetched via a protocol that does not support expiry times,
then use &lt;time&gt; hours as the expiry time.
<a href="#cachemaxexpire">CacheMaxExpire</a> does <strong>not</strong>
override.

<A name="nocache"><h2>NoCache</h2></A>
<strong>Syntax:</strong> NoCache <em>&lt;word/host/domain list&gt;</em><br>
<strong>Context:</strong> server config<br>
<strong>Status:</strong> Base<br>
<strong>Module:</strong> mod_proxy<br>
<strong>Compatibility:</strong> NoCache is only available in
Apache 1.1 and later.<p>

The NoCache directive specifies a list of words, hosts and/or domains, separated
by spaces. HTTP and non-passworded FTP documents from matched words, hosts or
domains are <em>not</em> cached 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>
  NoCache joes_garage.com some_host.co.uk bullwinkle.wotsamattau.edu
</pre>

'bullwinkle.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>
NoCache *
</pre>

disables caching completely.<p>

<hr>

<a name="configs"><h2>Common configuration topics</h2></a>

<ul>
<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 <i>xxx</i> download via FTP?</a>
<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>
</ul>

<a name="access"><h2>Controlling access to your proxy</h2>

You can control who can access your proxy via the normal &lt;Files&gt;
control block using the following example:<p>

<pre>
&lt;Files proxy:*&gt;
&lt;Limit GET&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;/Limit&gt;
&lt;/Files&gt;
</pre><p>

<a name="shortname"><h2>Using Netscape hostname shortcuts</h2>

There is an optional patch to the proxy module to allow Netscape-like
hostname shortcuts to be used. It's available
<a href="http://www.apache.org/dist/contrib/patches/1.2/netscapehost.patch">
here</a>.<p>

<a name="mimetypes"><h2>Why doesn't file type <i>xxx</i> download via FTP?</h2>

You probably don't have that particular file type defined as
<i>application/octet-stream</i> 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>

<a name="startup"><h2>Why does Apache start more slowly when using the
    proxy module?</h2>

If you're using the <code>ProxyBlock</code> or <code>NoCache</code>
directives, 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>

<a name="socks"><h2>Can I use the Apache proxy module with my SOCKS proxy?</h2>

Yes. Just build Apache with the rule <code>SOCKS4=yes</code> in your
<i>Configuration</i> 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_LFLAGS</code> definition, or build Apache
normally and run it with the <i>runsocks</i> 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>

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