I have been reading:

* IPSEC - The New Security Standard for the Internet, Intranets, and Virtual Private Networks
* Firewalls 24/7
* Hacking Exposed
* Honeypots Tracking Hackers
* Inside Internet Security
* Building Internet Firewalls
* Encryption Techniques with BASIC and C++ (a few years old - but still good)
Also, several Linux books: Linux Network Administrator's Guide, Linux Programming, etc.

I would recommend the first four books most of all. For Linux I like the O'Reilly books.


Hope this helps.....even if just a bit.