Mastering SSH for fun a profit.
Most Unix OSes have the wondrous joy of being able to take advantage of the benefits of OpenSSH, which is the best ssh implementation available in the entire world. People generally use it as a sort of encrypted and safe version of telnet, but it goes far far beyond that. For newer Linux users the power of SSH is going to be one of the major advantages of Linux over using Windows.
Several things you can use Openssh for (when combined with other programs):
Encrypted shell access.
Passwordless encrypted shell access.
Port forwarding.
Firewall penetration.
Server automation.
Remote encrypted file system.
Encrypted pseudo-FTP.
handy host to host secure file transfer.
Ad-hoc VPN.
Remote GUI access, either individual or entire desktop.
synchronising large amounts of data in a efficient manner
And a few others.
In order to increase the ease of use, safety, and maximise the advantages of Openssh the first thing you need to do is understand the various different sorts of authentication methods that you can use with OpenSSH.
Some examples (but they are not limited to):
Shared secret passwords (the default)
Private/Public keypair.
Private/Public keypair with passphrase.
Kerberos.
Multi-factor authentication (using PAM).. (say using RADIUS combined with One-Time-passcode, like FreeAuth or OpenID)
The most interesting from a average *nix user's perspective is going to be Private/Public keypair with passphrase. Using this authentication scheme combined with ssh-agent and a GUI front end you can easily setup password-less access to all your other computers.
Personally I have my desktop recently converted to a Linux-based media center, a work laptop, a file server, and a remote VPS. All of these I access using ssh from my single laptop. From my perspective they are just a single large cluster that I store various different resources and services on. All equally accessible.
So next post will be on how to setup a keypair, ssh-agent, and what to do with it.