I'm goging to ask you a question and give you a context to help you answer the question.
context: "Kerberos is a network authentication protocol which was originally created by the Massachusetts
Institute of Technology (MIT) as a way to securely provide authentication across a potentially
hostile network. The Kerberos protocol uses strong cryptography so that both a client and server
can prove their identity without sending any unencrypted secrets over the network. Kerberos can
be described as an identity-verifying proxy system and as a trusted third-party authentication
system. After a user authenticates with Kerberos, their communications can be encrypted to assure
privacy and data integrity. The current version of the protocol is version 5, described in RFC 4120. Several free implementations of this protocol are available, covering a wide range of operating systems."
question: what's the current version of the kerberos protocol?