Taken from
http://www.ccm.ece.vt.edu/~lscharf/samd/?topic=Linux&title=Lokkit+and+rsh :

Lokkit and rsh
Keywords:
Date Created: 2002-10-07
Author: Luke Scharf luke@vt.edu

The version of Lokkit that comes with RedHat 7.3 specifically blocks
outgoing remote shell (rsh) connections any time the firewall is up.

This is a good thing since rsh is amazngly insecure, but it still left
me scratching my head for a while when I tried to use rmt to control a
tape drive on a Solaris machine.