The Secure Shell (SSH) Protocol (henceforth SSHv2 signifying version 2.0) is a protocol designed for secure remote login and other secure network services over an insecure network. Standard methods are provided for setting up secure interactive shell sessions and for forwarding (“tunneling”) arbitrary TCP/IP ports and X11 connections (RFC 4251). In practical use, SSHv2 has four key elements in the handshake: Key exchange (kex), cipher, integrity check (MAC digest), authentication. Of these, key exchange and authentication have actual structural differences. Note that once the handshake has been completed (keys, used encryption, and integrity method are negotiated, and authentication is done), there is no real difference in the channel testing.