Apache module mod_proxy

Note:

This module was experimental in Apache 1.1.x. As of Apache 1.2, mod_proxy stability is greatly improved.

Summary

Directives

• ProxyRequests
• ProxyRemote
• ProxyPass
• ProxyBlock
• CacheRoot
• CacheSize
• CacheMaxExpire
• CacheDefaultExpire
• CacheLastModifiedFactor
• CacheGcInterval
• CacheDirLevels
• CacheDirLength
• NoCache

This allows or prevents Apache from functioning as a proxy server. Setting ProxyRequests to 'off' does not disable use of the ProxyPass directive.

ProxyRemote

This defines remote proxies to this proxy. <match> 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. <remote-server> is a partial URL for the remote server. Syntax:

  <remote-server> = <protocol>://<hostname>[:port]

  ProxyRemote http://goodguys.com/ http://mirrorguys.com:8000
  ProxyRemote * http://cleversite.com
  ProxyRemote ftp http://ftpproxy.mydomain.com:8080

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. <path> is the name of a local virtual path; <url> is a partial URL for the remote server. Suppose the local server has address http://wibble.org; then

   ProxyPass /mirror/foo http://foo.com

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 blocked 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:

  ProxyBlock joes_garage.com some_host.co.uk rocky.wotsamattau.edu

Note that 'wotsamattau' would also be sufficient to match 'wotsamattau.edu'.

Note also that

ProxyBlock *

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

CacheSize

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.

CacheGcInterval

Check the cache every <time> hours, and delete files if the space usage is greater than that set by CacheSize.

CacheMaxExpire

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 hours out of date.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

CacheLastModifiedFactor

If the origin HTTP server did not supply an expiry date for the document, then estimate one using the formula

  expiry-period = time-since-last-modification * <factor>

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

CacheDirLevels

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

CacheDirLength

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

CacheDefaultExpire

If the document is fetched via a protocol that does not support expiry times, then use <time> hours as the expiry time. CacheMaxExpire does not override.

NoCache

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 not 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:

  NoCache joes_garage.com some_host.co.uk bullwinkle.wotsamattau.edu

Note that 'wotsamattau' would also be sufficient to match 'wotsamattau.edu'.

Note also that

NoCache *

• Controlling access to your proxy
• Using Netscape hostname shortcuts
• Why doesn't file type xxx download via FTP?
• Why does Apache start more slowly when using the proxy module?
• Can I use the Apache proxy module with my SOCKS proxy?

Controlling access to your proxy

<Directory proxy:*>
<Limit GET PUT POST DELETE CONNECT OPTIONS>
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]
</Limit>
</Directory>

A <Files> block will also work, and is the only method known to work for all possible URLs in Apache versions earlier than 1.2b10.

Using Netscape hostname shortcuts

Why doesn't file type xxx download via FTP?

application/octet-stream        bin dms lha lzh exe class tgz taz

Why does Apache start more slowly when using the proxy module?

Can I use the Apache proxy module with my SOCKS proxy?

Some users have reported problems when using SOCKS version 4.2 on Solaris. The problem was solved by upgrading to SOCKS 4.3.

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.