[ Thanks to Kellie
for this link. ]
“Many developers use the excellent OpenSSH as a secure,
encrypted replacement for the venerable telnet and rsh commands.
One of OpenSSH’s more intriguing features is its ability to
authenticate users using the RSA and DSA authentication protocols,
which are based upon a pair of complementary numerical “keys”. One
of the main appeals of RSA and DSA authentication is the promise of
being able to establish connections to remote systems without
supplying a password. In this second article, Daniel introduces
ssh-agent (a private key cache) and keychain, a special bash script
designed to make key-based authentication incredibly convenient and
flexible.”