Secure replacements for ftp, telnet and rsh using MIT Kerberos Kerberos is a system for authenticating users and services on a network. Kerberos is a trusted third-party service. That means that there is a third party (the Kerberos server) that is trusted by all the entities on the network (users and services, usually called "principals"). This is the MIT reference implementation of Kerberos V5. This package contains secure replacements for ftp, telnet, rsh, rlogin, and rcp that use Kerberos for authentication.