Kerberos Client Support
System logins
pam_krb5 for any OS/application which supports PAM
(Pluggable Authentication Modules)
Many common applications require a recompile to enable
PAM (OpenSSH, sudo, xlockmore)
Replacement binaries for /bin/login, etc.
Many applications with native Kerberos support
Quite a few only support Kerberos IV, which requires
enabling Kerberos IV support on server