From Worms Knowledge Base
LeetF*ck is a now-obsolete connection program designed by Annelid during his 2003 program-making stint. Like most of his applications, it came about when he discovered something nifty could be done, and wanted a quick way to make it happen. LeetF*ck automatically determined a user's IP address upon initialization and forwarded the information to Worms Armageddon... a process handy back in the day for anyone with a dynamic IP address and a router who wanted to host games. (June 2007's W:A update now determines a client's true IP address in a more acceptable way, thus making this functionality unnecessary.)
But what everyone used leetF*ck for was the other feature... it set itself up as a local proxy on port 1337, and using a special serverlist link, Worms could be made to connect to WormNet through leetF*ck. The program then filtered various pieces of data from the communication, which could be used to display a custom rank (instead of the default lowest rank) or, most popularly, turn on the flaming power bars option in online games. These were effectively disabled in a beta in October 2004 (and completely disabled in March 2005) so are now also obsolete.
The program also had, at release, a built-in ping of sorts, to verify it was authorized to start up (so it could be disabled in the future if the need arose). Unfortunately the server it used was the old SFX data server, which went down about a year after the program's release. Perhaps more unfortunately, Annelid lost the source code for all his programs in late 2003 due to a hard drive failure, so LeetF*ck will remain a memory, and all his other releases will remain buggy.