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 a replacement for telnetd that uses Kerberos for authentication.