So, what is Kerberos?
“Kerberos is the name of the three-headed dog from ancient Greek mythology that guarded the gates of Hades. Kerberos is also a network authentication protocol invented at MIT way back in the 1980s. It became an IETF Standard in 1993. MIT released its Kerberos software as Open Source in 1987 and been enhancing it ever since. You can get it for free.