SSH

SSH (Secure Shell) is a protocol for secure remote login and other secure network services over an insecure network. It consists of three major components:

• The Transport Layer Protocol provides server authentication, confidentiality and integrity.
• The User Authentication Protocol authenticates the client-side user to the server. It runs over the transport layer protocol.
• The Connection Protocol multiplexes the encrypted tunnel into several logical channels. It runs over the user authentication protocol.

A Secure Shell (SSH) configuration enables a SSH server and client to authorize the negotiation of only those algorithms that are configured from the allowed list. The client sends a service request once a secure transport layer connection has been established. A second service request is sent after user authentication is complete. This allows new protocols to be defined and coexist with these protocols.