Linux

by Marcel Gagné

Once upon a time, when the Earth was green, plain text communications was the norm. We used TELNET to connect to systems where we needed to get work done. From a security perspective, plain-text communications is frought with dangers. Anyone running a network sniffer program, of which there are many, can snoop on every packet sailing across your network. If you are logging in using TELNET, that person can see your user name and password plain as day.

One way around this dilemma is to use the secure shell. OpenSSH is an open-source implementation of the secure shell protocol that comes with almost every major Linux distribution. The secure shell is much more than a simple way to keep your passwords to yourself. Logging securely certainly qualifies as the basics for OpenSSH and it's certainly useful, but there are some seriously cool SSH features that should make you wonder why you would use anything else to communicate (well, almost). For instance, it's possible to tunnel ports you may not have access to (if the machine is behind a firewall) through the SSH port. SSH makes it possible to run remote graphical sessions easily. You can even securely log in without a password. SSH is a veritable Swiss Army knife of OS toys.

Yes, I'll cover all those things later. First, the basics.