Security Benefits (continued)

Agent and Agent Forwarding
Secure Shell Agent is a way to authenticate to multiple Secure Shell servers that recognize your public key without having to re-type your passphrase each time. Additionally, by turning on agent forwarding, you can connect to a network of Secure Shell servers, eliminating the need to compromise the integrity of your private key.

Agent Forwarding passes authentication from the first SSH connection to the next, reauthenticating each time.

Notice that the private key only has to exist on the original SSHclient machine and the passphrase only needs to be typed when SSHClient connects to SSHServerA. Without agent forwarding enabled, each Secure Shell machine in the chain (except the last) would have to store a copy of the private key. SSHServerA, when authenticating SSHClient to SSHServerB becomes, in essence, a client and would require a private key to complete the authentication process. Agent support eliminates the need for the passphrase to be typed for each connection in the sequence.