I have just tried modifying Rsh.pm as you suggest, but on my system (RedHat 7.3) the connection is refused with the following message in the system log:

Sep 23 17:47:27 mondas rshd[23026]: Connection from 127.0.0.1 on illeg
+al port
[download]

Good point and worth a try though, if only to determine if your system has a broken rsh implementation (mmmm, security!) ;-)

JJ