MushLink
MushLink is primarily used on MUSHes. It uses a TCP connection in order to connect a MUD to the central server. In contrast to the other interMUD networks so far listed, MushLink's server actually connects to the MUD instead of having the MUD connect to the server. This connection consists of a bot that logs in as a special user. This user uses special commands in order to both display and receive messages from the MUD.
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