SSH, Secure Shell is a program to log into another computer over a network to run commands or to move files from one machine to another. SSH provides strong authentication and secure communications over insecure channels. SSH is a replacement for rlogin, rsh, rcp, and rdist. SSH protects a network from attacks. An attacker who has managed to take over a network can only force ssh to disconnect. He or she cannot play back the traffic or hijack the connection when encryption is enabled. When using SSH the entire login session, including transmission of password, is encrypted, therefore secure to any unwanted file access.