mod_proxy - Apache HTTP Server

mod_proxy - Apache HTTP Server
Modules
Directives
FAQ
Glossary
Apache HTTP Server Version 2.0
Apache
HTTP Server
Documentation
Version 2.0
Modules
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version of Apache httpd, which
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Apache Module mod_proxy
Available Languages:
en
Description:
HTTP/1.1 proxy/gateway server
Status:
Extension
Module Identifier:
proxy_module
Source File:
mod_proxy.c
Summary
Warning
Do not enable proxying with
ProxyRequests
until you have
secured your server
. Open proxy servers are dangerous both to your
network and to the Internet at large.
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
mod_proxy
mod_proxy_http
mod_proxy_ftp
and
mod_proxy_connect
. Thus, if you want to use
one or more of the particular proxy functions, load
mod_proxy
and
the appropriate module(s)
into the server (either statically at compile-time or dynamically
via the
LoadModule
directive).
In addition, extended features are provided by other modules.
Caching is provided by
mod_cache
and related
modules. The ability to contact remote servers using the SSL/TLS
protocol is provided by the
SSLProxy*
directives of
mod_ssl
. These additional modules will need
to be loaded and configured to take advantage of these features.
Directives
AllowCONNECT
NoProxy

ProxyBadHeader
ProxyBlock
ProxyDomain
ProxyErrorOverride
ProxyFtpDirCharset
ProxyIOBufferSize

ProxyMaxForwards
ProxyPass
ProxyPassReverse
ProxyPreserveHost
ProxyReceiveBufferSize
ProxyRemote
ProxyRemoteMatch
ProxyRequests
ProxyTimeout
ProxyVia
Topics
Forward and Reverse Proxies
Basic Examples
Controlling access to your proxy
FTP Proxy
Slow Startup
Intranet Proxy
Protocol Adjustments
See also
mod_cache
mod_proxy_http
mod_proxy_ftp
mod_proxy_connect
mod_ssl
Forward and Reverse Proxies
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
mod_cache
) to reduce network usage.
The forward proxy is activated using the
ProxyRequests
directive. Because
forward proxys allow clients to access arbitrary sites through
your server and to hide their true origin, it is essential that
you
secure your server
so that only
authorized clients can access the proxy before activating a
forward proxy.
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
ProxyPass
directive or the
[P]
flag to the
RewriteRule
directive. It is
not
necessary to turn
ProxyRequests
on in order to
configure a reverse proxy.
Basic Examples
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
mod_cache
Forward Proxy
ProxyRequests On
ProxyVia On

Order deny,allow
Deny from all
Allow from internal.example.com

Reverse Proxy
ProxyRequests Off

Order deny,allow
Allow from all

ProxyPass /foo http://foo.example.com/bar
ProxyPassReverse /foo http://foo.example.com/bar
Controlling access to your proxy
You can control who can access your proxy via the

control block as in
the following example:

Order Deny,Allow
Deny from all
Allow from 192.168.0

For more information on access control directives, see
mod_access
Strictly limiting access is essential if you are using a
forward proxy (using the
ProxyRequests
directive).
Otherwise, your server can be used by any client to access
arbitrary hosts while hiding his or her true identity. This is
dangerous both for your network and for the Internet at large.
When using a reverse proxy (using the
ProxyPass
directive with
ProxyRequests Off
), access control is less
critical because clients can only contact the hosts that you
have specifically configured.
FTP Proxy
Why doesn't file type
xxx
download via FTP?
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
How can I force an FTP ASCII download of
File
xxx
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
mod_proxy
's
default by suffixing the request with
;type=a
to force an
ASCII transfer. (FTP Directory listings are always executed in ASCII mode,
however.)
How can I access FTP files outside
of my home directory?
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:
ftp://
user
host
/%2f/etc/motd
How can I hide the FTP cleartext password
in my browser's URL line?
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.
user: anonymous
password: apache_proxy@
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:
ftp://
username
host
/myfile
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
ftp://
username
password
host
/myfile
in the first place).
Note
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.
Slow Startup
If you're using the
ProxyBlock
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.
Intranet Proxy
An Apache proxy server situated in an intranet needs to forward
external requests through the company's firewall (for this, configure
the
ProxyRemote
directive
to forward the respective
scheme
to the firewall proxy).
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
. 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.
Protocol Adjustments
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
SetEnv
directive.
These are the
force-proxy-request-1.0
and
proxy-nokeepalive
notes.

ProxyPass http://buggyappserver:7001/foo/
SetEnv force-proxy-request-1.0 1
SetEnv proxy-nokeepalive 1

AllowCONNECT
Directive
Description:
Ports that are allowed to
CONNECT
through the
proxy
Syntax:
AllowCONNECT
port
port
] ...
Default:
AllowCONNECT 443 563
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
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 override this default and
allow connections to the listed ports only.
Note that you'll need to have
mod_proxy_connect
present
in the server in order to get the support for the
CONNECT
at
all.
NoProxy
Directive
Description:
Hosts, domains, or networks that will be connected to
directly
Syntax:
NoProxy
host
host
] ...
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
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.example.com:81
NoProxy .example.com 192.168.112.0/21
The
host
arguments to the
NoProxy
directive are one of the following type list:
Domain
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
).
Examples
.com .apache.org.
To distinguish
Domain
s from
Hostname
s (both syntactically and semantically; a DNS domain can
have a DNS A record, too!),
Domain
s are always written with a
leading period.
Note
Domain name comparisons are done without regard to the case, and
Domain
s 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.
SubNet
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
192.168.0.0
the subnet 192.168.0.0 with an implied netmask of 16 valid bits
(sometimes used in the netmask form
255.255.0.0
192.168.112.0/21
the subnet
192.168.112.0/21
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.
IPAddr
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.
Example
192.168.123.7
Note
An
IPAddr
does not need to be resolved by the DNS system, so
it can result in more effective apache performance.
Hostname
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
Domain
s, see above) and must be resolvable
to at least one
IPAddr
(or often to a list
of hosts with different
IPAddr
s).
Examples
prep.ai.mit.edu
www.apache.org
Note
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
Hostname
s 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.
See also
DNS Issues

Directive
Description:
Container for directives applied to proxied resources
Syntax:
wildcard-url
> ...
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
Directives placed in

sections apply only to matching proxied content. Shell-style wildcards are
allowed.
For example, the following will allow only hosts in
yournetwork.example.com
to access content via your proxy
server:

Order Deny,Allow
Deny from all
Allow from yournetwork.example.com

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:

SetOutputFilter INCLUDES

ProxyBadHeader
Directive
Description:
Determines how to handle bad header lines in a
response
Syntax:
ProxyBadHeader IsError|Ignore|StartBody
Default:
ProxyBadHeader IsError
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
Compatibility:
Available in Apache 2.0.44 and later
The
ProxyBadHeader
directive determines the
behaviour of
mod_proxy
if it receives syntactically invalid
header lines (
i.e.
containing no colon). The following arguments
are possible:
IsError
Abort the request and end up with a 502 (Bad Gateway) response. This is
the default behaviour.
Ignore
Treat bad header lines as if they weren't sent.
StartBody
When receiving the first bad header line, finish reading the headers and
treat the remainder as body. This helps to work around buggy backend servers
which forget to insert an empty line between the headers and the body.
ProxyBlock
Directive
Description:
Words, hosts, or domains that are banned from being
proxied
Syntax:
ProxyBlock *|
word
host
domain
word
host
domain
] ...
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
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
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. That may slow down the startup time of the server.
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.
ProxyDomain
Directive
Description:
Default domain name for proxied requests
Syntax:
ProxyDomain
Domain
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
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.example.com:81
NoProxy .example.com 192.168.112.0/21
ProxyDomain .example.com
ProxyErrorOverride
Directive
Description:
Override error pages for proxied content
Syntax:
ProxyErrorOverride On|Off
Default:
ProxyErrorOverride Off
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
Compatibility:
Available in version 2.0 and later
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).
ProxyFtpDirCharset
Directive
Description:
Define the character set for proxied FTP listings
Syntax:
ProxyFtpDirCharset
character set
Default:
ProxyFtpDirCharset ISO-8859-1
Context:
server config, virtual host, directory
Status:
Extension
Module:
mod_proxy
Compatibility:
Available in Apache 2.0.62 and later
The
ProxyFtpDirCharset
directive defines the
character set to be set for FTP directory listings in HTML generated by
mod_proxy_ftp
ProxyIOBufferSize
Directive
Description:
Determine size of internal data throughput buffer
Syntax:
ProxyIOBufferSize
bytes
Default:
ProxyIOBufferSize 8192
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
The
ProxyIOBufferSize
directive adjusts the size
of the internal buffer, which is used as a scratchpad for the data between
input and output. The size must be less or equal
8192
In almost every case there's no reason to change that value.

Directive
Description:
Container for directives applied to regular-expression-matched
proxied resources
Syntax:
regex
> ...
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
The

directive is
identical to the

directive, except it matches URLs
using regular expressions.
ProxyMaxForwards
Directive
Description:
Maximium number of proxies that a request can be forwarded
through
Syntax:
ProxyMaxForwards
number
Default:
ProxyMaxForwards 10
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
Compatibility:
Available in Apache 2.0 and later
The
ProxyMaxForwards
directive specifies the
maximum number of proxies through which a request may pass, if there's no
Max-Forwards
header supplied with the request. This is
set to prevent infinite proxy loops, or a DoS attack.
Example
ProxyMaxForwards 15
ProxyPass
Directive
Description:
Maps remote servers into the local server URL-space
Syntax:
ProxyPass [
path
] !|
url
Context:
server config, virtual host, directory
Status:
Extension
Module:
mod_proxy
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
then
ProxyPass /mirror/foo/ http://backend.example.com/
will cause a local request for
to be internally converted
into a proxy request to
The
directive is useful in situations where you don't want
to reverse-proxy a subdirectory,
e.g.
ProxyPass /mirror/foo/i !
ProxyPass /mirror/foo http://backend.example.com
will proxy all requests to
/mirror/foo
to
backend.example.com
except
requests made to
/mirror/foo/i
Note
Order is important. you need to put the exclusions
before
the
general proxypass directive.
When used inside a

section, the first argument is omitted and the local
directory is obtained from the

The
ProxyRequests
directive should
usually be set
off
when using
ProxyPass
If you require a more flexible reverse-proxy configuration, see the
RewriteRule
directive with the
[P]
flag.
ProxyPassReverse
Directive
Description:
Adjusts the URL in HTTP response headers sent from a reverse
proxied server
Syntax:
ProxyPassReverse [
path
url
Context:
server config, virtual host, directory
Status:
Extension
Module:
mod_proxy
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
ProxyPass
directive.
For example, suppose the local server has address
; then
ProxyPass /mirror/foo/ http://backend.example.com/
ProxyPassReverse /mirror/foo/ http://backend.example.com/
will not only cause a local request for the
to be internally converted
into a proxy request to
(the functionality
ProxyPass
provides here). It also takes care
of redirects the server
backend.example.com
sends: when
is redirected by him to
Apache adjusts this to
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
UseCanonicalName
directive.
Note that this
ProxyPassReverse
directive can
also be used in conjunction with the proxy pass-through feature
RewriteRule ... [P]
) from
mod_rewrite
because its doesn't depend on a corresponding
ProxyPass
directive.
When used inside a

section, the first argument is omitted and the local
directory is obtained from the

ProxyPreserveHost
Directive
Description:
Use incoming Host HTTP request header for proxy
request
Syntax:
ProxyPreserveHost On|Off
Default:
ProxyPreserveHost Off
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
Compatibility:
Available in Apache 2.0.31 and later.
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.
ProxyReceiveBufferSize
Directive
Description:
Network buffer size for proxied HTTP and FTP
connections
Syntax:
ProxyReceiveBufferSize
bytes
Default:
ProxyReceiveBufferSize 0
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
The
ProxyReceiveBufferSize
directive specifies an
explicit (TCP/IP) network buffer size for proxied HTTP and FTP connections,
for increased throughput. It has to be greater than
512
or set
to
to indicate that the system's default buffer size should
be used.
Example
ProxyReceiveBufferSize 2048
ProxyRemote
Directive
Description:
Remote proxy used to handle certain requests
Syntax:
ProxyRemote
match
remote-server
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
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
scheme
://
hostname
[:
port
scheme
is effectively 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:8080
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.
ProxyRemoteMatch
Directive
Description:
Remote proxy used to handle requests matched by regular
expressions
Syntax:
ProxyRemoteMatch
regex
remote-server
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
The
ProxyRemoteMatch
is identical to the
ProxyRemote
directive, except the
first argument is a regular expression match against the requested URL.
ProxyRequests
Directive
Description:
Enables forward (standard) proxy requests
Syntax:
ProxyRequests On|Off
Default:
ProxyRequests Off
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
This allows or prevents Apache from functioning as a forward proxy
server. (Setting ProxyRequests to
Off
does not disable use of
the
ProxyPass
directive.)
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
mod_proxy_http
or
mod_proxy_ftp
(or both) present in the server.
Warning
Do not enable proxying with
ProxyRequests
until you have
secured your server
. Open proxy servers are dangerous
both to your network and to the Internet at large.
ProxyTimeout
Directive
Description:
Network timeout for proxied requests
Syntax:
ProxyTimeout
seconds
Default:
ProxyTimeout 300
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
Compatibility:
Available in Apache 2.0.31 and later
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.
ProxyVia
Directive
Description:
Information provided in the
Via
HTTP response
header for proxied requests
Syntax:
ProxyVia On|Off|Full|Block
Default:
ProxyVia Off
Context:
server config, virtual host
Status:
Extension
Module:
mod_proxy
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
RFC 2616
(HTTP/1.1), section
14.45 for an explanation of
Via:
header lines.
If set to
Off
, which is the default, no special processing
is performed. If a request or reply contains a
Via:
header,
it is passed through unchanged.
If set to
On
, each request and reply will get a
Via:
header line added for the current host.
If set to
Full
, each generated
Via:
header
line will additionally have the Apache server version shown as a
Via:
comment field.
If set to
Block
, every proxy request will have all its
Via:
header lines removed. No new
Via:
header will
be generated.
Available Languages:
en
Copyright 2013 The Apache Software Foundation.
Licensed under the
Apache License, Version 2.0
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