Secure Shell:

- Secure Shell (SSH), sometimes known as Secure Socket Shell, is a Unix-based command interface and protocol for securely getting access to a remote computer. It is widely used by network administrators to control Web and other kinds of servers remotely. SSH is actually a suite of three utilities - slogin, ssh, and scp - that are secure versions of the earlier UNIX utilities, rlogin, rsh, and rcp. SSH commands are encrypted and secure in several ways. Both ends of the client/server connection are authenticated using a digital certificate, and passwords are protected by being encrypted. SSH uses RSA public key cryptography for both connection and authentication. Encryption algorithms include Blowfish, DES, and IDEA. IDEA is the default.

SSH2, the latest version, is a proposed set of standards from the Internet Engineering Task Force (IETF).

SSH was developed in the mid-1990s by Helsinki University researcher Tatu Ylönen as a secure alternative to non-secure telnet, rlogin and rsh programs for Unix servers. SSH-2, a more advanced version introduced in 1998, was standardized by the IETF and is not compatible with SSH-1.