Secure Shell (SSH)

Secure shell is a network protocol for the creation of encrypted connections. In its original and purest form, it is used to open a remote terminal and execute commands. However, the protocol can also be used for file transfer (SCP, SFTP); as an encrypted transport protocol for other, possible less strongly secured protocols; and for port forwarding—the redirection of requests for certain ports to ports on other servers—a technique often used to allow machines on different sides of a firewall to communicate.