The list of programs includes: telnet, ftp, licq, cvs, smth else? Project implements dynamic library, that can be preloaded before program run. The library substitutes some system calls (connect(), gethostbyaddr(), gethostbyname()), with calls, which makes TCP/IP connection through HTTP proxy. This allows client programs behind HTTP proxy work with Internet without limitations.
I have everything working through our proxy at work. These days most programs are pretty good about respecting the
http_proxy environment variable, and then some others have their own funky configuration like Firefox, Eclipse, and Subversion (see here). I’m jotting down a note about httppc, because I’m sure that now I’ve said that all my programs work through the proxy, I will soon find one that doesn’t and will be searching for something like this.