Kerberos is a computer network authentication protocol, which allows nodes communicating over a non-secure network to prove their identity to one another in a secure manner. It is also a suite of free software published by Massachusetts Institute of Technology that implements this protocol. Its designers aimed primarily at a client-server model, and it provides mutual authentication both the user and the server verify each other's identity. Kerberos protocol messages are protected against eavesdropping and replay attacks.