A large number of operating systems can use this standard. Most notably, it is the default authentication system used in Windows 2000 and Windows Server 2003 domains. Clients in these domains that run either OS or Windows XP Professional use it by default for network authentication. Kerberos can be implemented in a wide range of other operating systems, including many Unix systems. Residents of the United States and Canada can obtain a copy of Kerberos from MIT (Massachusetts Institute of Technology). Many other sources, both open-source and commercial exist (Click here for a couple of them).
It is possible in some cases to integrate Kerberos implementations in different OSes with each other, but you should do testing, as it is probably not possible to integrate all versions of Kerberos.
This was first published in April 2003