http://www.socks.nec.comSOCKS is a proxy-building toolkit that allows you to convert standard TCP client programs to proxied versions of those same programs. There are two parts to SOCKS: client libraries and a generic server. Client libraries are available for most Unix platforms, as well as for acintosh and Windows systems. The generic server runs on most Unix platforms and can be used by any of the client libraries, regardless of their platform. SOCKS was originally freely available; freely available and commercial versions, with somewhat different features, are now available from NEC.
ftp://coast.cs.purdue.edu/pub/tools/unix/udprelay-0.2.tar.gzThis package, by Tom Fitzgerald, is a proxy system that provides much the same functionality for UDP-based clients that SOCKS provides for TCP-based clients.
http://www.mmedia.is/~bre/tircproxy/tircproxy is an IRC proxy that provides intelligent proxying to increase the safety of IRC while making it work through a firewall. It is discussed in Chapter 19, "Real-Time Conferencing Services".