ffproxy is a filtering HTTP proxy server. It is able to filter
by host, URL, and header. Custom header entries can be filtered
and added. It can even drop its privileges and optionally
chroot() to some directory. Logging to syslog() is supported,
as is using another auxiliary proxy server. Contacting IPv6
servers is supported and allows transparent IPv6 over IPv4
browsing.

WWW: http://ffproxy.sourceforge.net