AberChat
AberChat is used primarily by the type of MUD known as AberMUD. It uses TCP connections to connect each MUD to a central server. Some of the more distinctive characteristics of AberChat is that it does not rely on client MUDs to keep track of the other MUDs on a network, and it does not update a local list when other MUDs on a network become available or unavailable. Instead, in order to see what MUDs are out there, MUD users can send a request for a list of MUDs on the network to the server, which replies with a complete list.
There is both a public and a private AberChat network. Both require the server administrator to manually add a new MUD to the network.
Read more about this topic: Inter MUD