I just bought a book "Maximum Linux Security/Second Edition" by SAMS. It's very good for Linux user...I found information How Linux user protect their Linux servers and workstations from unauthorized intrusions and other external threads.Also you read about Portsentry,tripwire,Logcheck,Snort,Sniffer Cold,Hunt ,Ethereal ,Bastille firewall Linux,Mason firewall ,How to configure and run(in a safe away) many popular Linux application like sendmail,apache..etc..etc. And The most important thing you will learn configuration tips and techniques to help eliminate security thread to your Linux Box.
I think that's a good read specially like my self...as beginner *nix user.

Check it out if you like reading a books..