Whitepapers & Publications at the honeynet project: http://www.honeynet.org/papers/
Good discussion of how and more importantly, WHY you must secure your system. There's a whole sub-culture of people devoted to hacking systems - more to the point, they've created scripts and programs to allow nearly anyone, even those who are very un-sophisticated, to very effectively compromise a system, hide the fact that they've done so, then use your system as a springboard to bigger and better things. Highly recommended.Encryption and Security-related Resources
A large collection of links.SSH Protocols and Secure Shell
One commonly used suite of software to secure connections made across insecure networks. Free for strictly non-commercial use (at least the version 1.* is).OpenSSH is a FREE version of the SSH suite
Truly free, both as in 'free beer' and 'free speech'. With the expiration of the RSA patents, this may (I am not a lawyer) now be legal for all uses, including commercial.