Here you can find a bit of documentation that may help you get Kerberos running on a Red Hat Linux system. There are many services that can be "kerberized", but here I discuss only system logon using openssh and using the existing logon methods: xdm, login (telnet/console).
One benefit that kerberized SSH gives you is the ability to ssh from one machine to another without typing a password, and without the risk that a private key might be compromised.
Kerberos 5 client HOWTO, updated for
Red Hat Linux 8.0
Kerberos 5 client HOWTO, older Red Hat
versions
(old text version)