All you ever wanted to know about the inner workings of Intermud-3 but were
afraid to ask your mutha. This document covers most if not all of it, from
the packet structures to router design concepts.
It takes a fair bit of work to write an Intermud-3 client, and a fair bit
more if the target mud is not based on the MudOS driver. This page links to some
prewritten clients which might be modified to suit.