syntax: banish <player> 
'Kicks' the named player and adds their current IP address to the banish file.  This will prevent the named player from logging into the server (from their current IP).
This is an in-game version of the ban function meant for short term relief of persistant goons and for DMs who do not have shell access.
It is probably a good idea to clear out the banish file (var/crossfire/banish_file) on a regular basis and delete or move any entries to the ban_file if desired.