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mod_proxy.c file for Apache 1.1.x,
or the modules/proxy subdirectory for Apache 1.2, and
is not compiled in by default. It provides for an HTTP
1.0 caching proxy
server. It is only available in Apache 1.1 and later. Common configuration
questions are addressed after the directive
descriptions.
This module was experimental in Apache 1.1.x. As of Apache 1.2, mod_proxy stability is greatly improved.
FTP,
CONNECT (for SSL),
HTTP/0.9, and
HTTP/1.0.
The module can be configured to connect to other proxy modules for these
and other protocols.
ProxyRequests OffThis allows or prevents Apache from functioning as a proxy server. Setting ProxyRequests to 'off' does not disable use of the ProxyPass directive.
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]<protocol> is the protocol that should be used to communicate with the remote server; only "http" is supported by this module.
Example:
ProxyRemote http://goodguys.com/ http://mirrorguys.com:8000 ProxyRemote * http://cleversite.com ProxyRemote ftp http://ftpproxy.mydomain.com:8080In the last example, the proxy will forward FTP requests, encapsulated as yet another HTTP proxy request, to another proxy which can handle them.
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/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>.
This directive lets Apache adjust the URL in the Location header on HTTP redirect responses. For instance 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.
<path> is the name of a local virtual path.
<url> is a partial URL for the remote server - the same way they are
used for the ProxyPass directive.
Example:
Suppose the local server has address http://wibble.org/; then
ProxyPass /mirror/foo/ http://foo.com/ ProxyPassReverse /mirror/foo/ http://foo.com/will not only 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> (the functionality ProxyPass provides here). It also takes care of redirects the server foo.com sends: when http://foo.com/bar is redirected by him to http://foo.com/quux Apache adjusts this to http://wibble.org/mirror/foo/quux before forwarding the HTTP redirect response to the client.
Note that this ProxyPassReverse directive can also by used in conjunction with the proxy pass-through feature ("RewriteRule ... [P]") from mod_rewrite because its doesn't depend on a corresponding ProxyPass directive.
The AllowCONNECT directive specifies a list of port numbers
to which the proxy CONNECT method may connect.
Today's browsers use this method when a https connection
is requested and proxy tunneling over http is in effect.
By default, only the default https port (443) and the default
snews port (563) are enabled. Use the AllowCONNECT
directive to overrride this default and allow connections to the
listed ports only.
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'rocky.wotsamattau.edu' would also be matched if referenced by IP address.
Note that 'wotsamattau' would also be sufficient to match 'wotsamattau.edu'.
Note also that
ProxyBlock *blocks connections to all sites.
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.
Example:
ProxyReceiveBufferSize 2048
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).
Example:
ProxyRemote * http://firewall.mycompany.com:81 NoProxy .mycompany.com 192.168.112.0/21The arguments to the NoProxy directive are one of the following type list:
See Also: DNS Issues
See Also: DNS Issues
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 Domain appended will be generated.
Example:
ProxyRemote * http://firewall.mycompany.com:81 NoProxy .mycompany.com 192.168.112.0/21 ProxyDomain .mycompany.com
This directive controls the use of the Via: 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 Via: header lines.
If an http transfer that is being cached is cancelled, the proxy module will complete the transfer to cache if more than the percentage specified has already been transferred.
This is a percentage, and must be a number between 1 and 100, or 0 to use the default. 100 will cause a document to be cached only if the transfer was allowed to complete. A number between 60 and 90 is recommended.
Sets the name of the directory to contain cache files; this must be
writable by the httpd server.
(see the User directive).
Setting CacheRoot enables proxy cacheing; without defining
a CacheRoot, proxy functionality will be available
if ProxyRequests are set to On, but no
cacheing will be available.
CacheSize 5
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.
Depending on the expected proxy traffic volume and CacheGcInterval,
use a value which is at least 20 to 40 % lower than the available space.
Check the cache every <time> hours, and delete files if the space
usage is greater than that set by CacheSize. Note that <time> accepts a
float value, you could for example use CacheGcInterval 1.5 to
check the cache every 90 minutes. (If unset, no garbage collection will
be performed, and the cache will grow indefinitely.)
Note also that the larger the CacheGcInterval, the more
extra space beyond the configured CacheSize will be
needed for the cache between garbage collections.
CacheMaxExpire 24Cachable 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 0.1If 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>For example, if the document was last modified 10 hours ago, and <factor> is 0.1, then the expiry period will be set to 10*0.1 = 1 hour.
If the expiry-period would be longer than that set by CacheMaxExpire, then the latter takes precedence.
CacheDirLevels 3CacheDirLevels sets the number of levels of subdirectories in the cache. Cached data will be saved this many directory levels below CacheRoot.
CacheDirLength 1CacheDirLength sets the number of characters in proxy cache subdirectory names.
CacheDefaultExpire 1If 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 this setting.
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'bullwinkle.wotsamattau.edu' would also be matched if referenced by IP address.
Note that 'wotsamattau' would also be sufficient to match 'wotsamattau.edu'.
Note also that
NoCache *disables caching completely.
<Directory proxy:*> 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] </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.
application/octet-stream bin dms lha lzh exe class tgz taz
ProxyBlock or NoCache
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.
SOCKS4=yes in your
Configuration file, and follow the instructions there. SOCKS5
capability can be added in a similar way (there's no SOCKS5
rule yet), so use the EXTRA_LDFLAGS definition, or build Apache
normally and run it with the runsocks wrapper provided with SOCKS5,
if your OS supports dynamically linked libraries.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.
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 NoProxy directive is useful for specifying which hosts belong to the intranet and should be accessed directly.
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 ProxyDomain directive is used and the server is configured for proxy service, 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.
