SSH Protocols and Secure Shell

  Secure Shell is the secure login program that revolutionized remote
management of networks hosts over the Internet.  It is a powerful,
very easy-to-use program that uses strong cryptography for protecting
all transmitted confidential data, including passwords, binary files,
and administrative commands.

The benefits of SSH include:

o Automatic authentication of users, no passwords sent in cleartext to
  prevent the stealing of passwords.
o Multiple strong authentication methods that prevent such security
  threats as spoofing identity.
o Authentication of both ends of connection, the server and the client
  are authenticated to prevent identity spoofing, trojan horses, etc. 
o Automatic authentication using agents to enable strong
  authentication to multiple systems with a single-sign-on.
o Encryption and compression of data for security and speed.
o Secure file transfer.
o Tunneling and encryption of arbitrary connections.

WWW: http://www.ssh.fi/