ssh-keygen -- Generates public/private key pair for RSA authentication usage.
            ssh-agent -- manages ssh identity keys -- hands keys to an inquiry from an sshd
            ssh-add -- adds private key to ssh-agent's management
            ssh -- This is the client side program, similar to rsh and telnet
            scp -- This is similiar to rcp

            In order to use ssh to the best of its abilities, one needs a public/private key.  Simply run:

                            ssh-keygen

            Might want to chose at least the 700+ thing in order for decent security.  Choose a good sentence for your pass phrase. Something not easily guessable.

             Once your keys are generated they are stored in ~/.ssh/identity.pub and ~/.ssh/identity.  I strongly suggest you copy ~/.ssh/identity.pub to ~/.ssh/authorized_keys.  In order to provide seamless operation, mimicing rsh/rlogin, one will need to do something similar to:

                                exec ssh-agent <shell>     e.g.    exec ssh-agent /bin/tcsh
                                ssh-add  (it will ask for your passphrase)

      And then, once you have your identity.pub key stored in the authorized_keys file for a remote user, one can simply do:

                            ssh -l <user>  <remote host>

        or

                            scp <user>@<remotehost>:/remote/file/location  /local/file

                            scp /local/file <user>@<remotehost>:/remote/file/location

    In my .xsession, the last line is:

ssh-agent xterm

    Within the xterm, I then run:

                    ssh-add
           <windowmanager>

    This allows me to ssh to any machine without having to type my password or passphrase over and over.  The ssh-agent stores the public key provided via the ssh-add command and hands it off upon request.

    Some users might have ssh-askpass in their .xsession.  This is supposed to provide the same functionality as the steps above, but I found that it didn't work as well as I'd hoped.  YMMV.

If your identity.pub file/contents are included in a users authorized_keys file, you can log into a remote machine as that user provided you enter your passphrase correctly.  A user may have different passphrases and identities as one wants.