transproxy - transparently proxy HTTP requests.

This program is used with ipfw's fwd rules or Darren Reed's IPFILTER
package, and is used to intercept HTTP requests and divert them to a
HTTP proxy server (eg: squid), without requiring user intervention or
configuration.

It accepts connections on the redirected port, connects to the real proxy
server, and transports data between the two sockets. The original HTTP
request is modified to allow the HTTP proxy server to fetch the correct
document. In most cases this doesn't cause any DNS activity.

Unlike some other transparent proxy solutions, this does not require the
HTTP proxy server to run on the machine itself.

See /usr/local/sbin/tproxyrun for an example of how to add filter rules
and start tproxy. Also see /usr/local/sbin/tproxywatch for an example of
how to ensure that tproxy keeps running regardless of faults.

WWW: http://transproxy.sourceforge.net/