Secure telnet server supporting 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 a replacement for telnetd that uses Kerberos for authentication.