Kerberos V5 Installation Guide
Kerberos V4 used port 750. If necessary, you can run on
both ports for backward compatibility.
If you are fortunate enough to
have a previous version of Kerberos V5 or V4 installed, and the Kerberos
rlogin is first in your path, you can setup `.k5login' or
`.klogin' respectively to allow you access.