Battle.net servers are somewhat unreliable, not infrequently disconnecting players in the middle of a game, and lag can become bad sometimes. To mitigate these difficulties, a group of gamer/programmers produced a freely available clone of battle.net called bnetd. Blizzard games normally only work over the Internet with battle.net, but bnetd allows gamers to run their own private server.
In February 2002, lawyers retained by Blizzard threatened legal action under provisions of the DMCA against the bnetd developers, and the project was officially halted. As of June 2002, Blizzard lawyers were in negotiations with attorneys from the Electronic Frontier Foundation to resolve the case without a full trial.
See also the External Links section at the Blizzard Entertainment article.