this is a pretty good article that is a little dated, but still very informative at freeos.com.
since this is Network Security for Dummies Q&A, maybe this should be the first step for unix.com users to check for general and more specific info on how to 'harden' their linux box.
some of this info applies to other OS's aswell:
http://www.freeos.com/articles/2896/
wheres part one you ask? right here 
:
Titan is an opensource utility that can be a good initial lockdown for Linux and other systems. They also have a nice page that goes over some of the things the script actually does:
http://www.fish.com/titan/TITAN_linux.html
Cheers,
Keith
So, any good security articles anyone comes across, POST THEM HERE! 
Hi,
Some links...
http://www.nacs.uci.edu/security/hardening.html
http://www.linuxmagazine.com/2002-09/harden_list.htm
http://www.megalinux.net/archives/000113.html
http://www.security.ku.edu/hardening/linux.shtml
I think that it is important to look at the security from more than just a host perspective. Let's harden the system and drop a HIDS (Host based IDS), but also not forget watching our network as well. I've used Snort and the front end ACID with good success.
Keith
there is a nice toolbox for solaris:
http://wwws.sun.com/software/security/jass/index.html
greetings Pre�y
has anyone tried BRO another HIDS on the lines of Snort except that it uses regular expressions rather content based strings for signature matching.
This page is not found. might be moved
esham