Do not enable proxying with
This module implements a proxy/gateway for Apache. It implements
proxying capability for FTP, CONNECT (for SSL),
HTTP/0.9, HTTP/1.0, and HTTP/1.1.
The module can be configured to connect to other proxy modules for these
and other protocols.
Apache's proxy features are divided into several modules in
addition to
In addition, extended features are provided by other modules.
Caching is provided by SSLProxy* directives of
Apache can be configured in both a forward and reverse proxy mode.
An ordinary forward proxy is an intermediate server that sits between the client and the origin server. In order to get content from the origin server, the client sends a request to the proxy naming the origin server as the target and the proxy then requests the content from the origin server and returns it to the client. The client must be specially configured to use the forward proxy to access other sites.
A typical usage of a forward proxy is to provide Internet
access to internal clients that are otherwise restricted by a
firewall. The forward proxy can also use caching (as provided
by
The forward proxy is activated using the
A reverse proxy, by contrast, appears to the client just like an ordinary web server. No special configuration on the client is necessary. The client makes ordinary requests for content in the name-space of the reverse proxy. The reverse proxy then decides where to send those requests, and returns the content as if it was itself the origin.
A typical usage of a reverse proxy is to provide Internet users access to a server that is behind a firewall. Reverse proxies can also be used to balance load among several back-end servers, or to provide caching for a slower back-end server. In addition, reverse proxies can be used simply to bring several servers into the same URL space.
A reverse proxy is activated using the [P] flag to the
The examples below are only a very basic idea to help you get started. Please read the documentation on the individual directives.
In addition, if you wish to have caching enabled, consult
the documentation from
You can control who can access your proxy via the
For more information on access control directives, see
Strictly limiting access is essential if you are using a
forward proxy (using the ProxyRequests Off), access control is less
critical because clients can only contact the hosts that you
have specifically configured.
You probably don't have that particular file type defined as
application/octet-stream in your proxy's mime.types
configuration file. A useful line can be
application/octet-stream bin dms lha lzh exe class tgz taz
In the rare situation where you must download a specific file using the
FTP ASCII transfer method (while the default transfer is in
binary mode), you can override ;type=a to force an
ASCII transfer. (FTP Directory listings are always executed in ASCII mode,
however.)
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 a
solution which is also used by other popular proxy servers like the Squid Proxy Cache. 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). For example, to retrieve the file
/etc/motd, you would use the URL:
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 anonymous login to the FTP server, i.e.,
This works for all popular FTP servers which are configured for anonymous access.
For a personal login with a specific username, you can embed the user name into the URL, like in:
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
in the first place).
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.
If you're using the
An Apache proxy server situated in an intranet needs to forward
external requests through the company's firewall (for this, configure
the
Users within an intranet tend to omit the local domain name from their
WWW requests, thus requesting "http://somehost/" instead of
http://somehost.example.com/. Some commercial proxy servers
let them get away with this and simply serve the request, implying a
configured local domain. When the
For circumstances where you have a application server which doesn't
implement keepalives or HTTP/1.1 properly, there are 2 environment
variables which when set send a HTTP/1.0 with no keepalive. These are set
via the
These are the force-proxy-request-1.0 and
proxy-nokeepalive notes.
Directives placed in
For example, the following will allow only hosts in
yournetwork.example.com to access content via your proxy
server:
The following example will process all files in the foo
directory of example.com through the INCLUDES
filter when they are sent through the proxy server:
The
IsErrorIgnoreStartBodyThe
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.
This option should normally be turned Off. It is mostly
useful in special configurations like proxied mass name-based virtual
hosting, where the original Host header needs to be evaluated by the
backend server.
This allows or prevents Apache from functioning as a forward proxy
server. (Setting ProxyRequests to Off does not disable use of
the
In a typical reverse proxy configuration, this option should be set to
Off.
In order to get the functionality of proxying HTTP or FTP sites, you
need also
Do not enable proxying with
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:
scheme is effectively the protocol that should be used to
communicate with the remote server; only http is supported by
this module.
In the last example, the proxy will forward FTP requests, encapsulated as yet another HTTP proxy request, to another proxy which can handle them.
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.
The
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 and cannot include a query string.
Suppose the local server has address http://example.com/;
then
will cause a local request for
http://example.com/mirror/foo/bar to be internally converted
into a proxy request to http://backend.example.com/bar.
The ! directive is useful in situations where you don't want
to reverse-proxy a subdirectory, e.g.
will proxy all requests to /mirror/foo to
backend.example.com except requests made to
/mirror/foo/i.
Order is important. you need to put the exclusions before the general proxypass directive.
When used inside a
If you require a more flexible reverse-proxy configuration, see the
[P] flag.
This directive lets Apache adjust the URL in the Location,
Content-Location and URI 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.
Only the HTTP response headers specifically mentioned above will be rewritten. Apache will not rewrite other response headers, nor will it rewrite URL references inside HTML pages. This means that if the proxied content contains absolute URL references, they will by-pass the proxy. A third-party module that will look inside the HTML and rewrite URL references is Nick Kew's mod_proxy_html.
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
For example, suppose the local server has address
http://example.com/; then
will not only cause a local request for the
http://example.com/mirror/foo/bar to be internally converted
into a proxy request to http://backend.example.com/bar
(the functionality ProxyPass provides here). It also takes care
of redirects the server backend.example.com sends: when
http://backend.example.com/bar is redirected by him to
http://backend.example.com/quux Apache adjusts this to
http://example.com/mirror/foo/quux before forwarding the HTTP
redirect response to the client. Note that the hostname used for
constructing the URL is chosen in respect to the setting of the
Note that this RewriteRule ... [P]) from
When used inside a
CONNECT through the
proxyThe 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
Note that you'll need to have CONNECT at
all.
The
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
blocks connections to all sites.
The 512 or set
to 0 to indicate that the system's default buffer size should
be used.
The 8192.
In almost every case there's no reason to change that value.
The Max-Forwards header supplied with the request. This is
set to prevent infinite proxy loops, or a DoS attack.
This directive is only useful for Apache proxy servers within
intranets. The
The host arguments to the
A Domain 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 (i.e., the suffixes of the hostnames are all ending in Domain).
To distinguish Domains from Hostnames (both syntactically and semantically; a DNS domain can have a DNS A record, too!), Domains are always written with a leading period.
Domain name comparisons are done without regard to the case, and
Domains are always assumed to be anchored in the root of the
DNS tree, therefore two domains .MyDomain.com and
.mydomain.com. (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.
A SubNet 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 SubNet. 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.) Examples:
192.168 or 192.168.0.0255.255.0.0)192.168.112.0/21192.168.112.0/21 with a netmask of 21
valid bits (also used in the form 255.255.248.0)As a degenerate case, a SubNet with 32 valid bits is the equivalent to an IPAddr, while a SubNet with zero valid bits (e.g., 0.0.0.0/0) is the same as the constant _Default_, matching any IP address.
A IPAddr 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.
An IPAddr does not need to be resolved by the DNS system, so it can result in more effective apache performance.
A Hostname is a fully qualified DNS domain name which can be resolved to one or more IPAddrs via the DNS domain name service. It represents a logical host (in contrast to Domains, see above) and must be resolvable to at least one IPAddr (or often to a list of hosts with different IPAddrs).
In many situations, it is more effective to specify an IPAddr in place of a Hostname 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.
Hostname comparisons are done without regard to the case,
and Hostnames are always assumed to be anchored in the root
of the DNS tree, therefore two hosts WWW.MyDomain.com
and www.mydomain.com. (note the trailing period) are
considered equal.
This directive allows a user to specifiy a timeout on proxy requests. This is useful 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.
This directive is only useful for Apache proxy servers within
intranets. The
Via HTTP response
header for proxied requestsThis 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 RFC 2616 (HTTP/1.1), section
14.45 for an explanation of Via: header lines.
Off, which is the default, no special processing
is performed. If a request or reply contains a Via: header,
it is passed through unchanged.On, each request and reply will get a
Via: header line added for the current host.Full, each generated Via: header
line will additionally have the Apache server version shown as a
Via: comment field.Block, every proxy request will have all its
Via: header lines removed. No new Via: header will
be generated.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).