Building Internet Firewalls
$26.36

Altogether the best book about firewalls available right now -- at least the Internet brand <g>.  Often called the "Holy Grail of Firewalls" and the like.  Altogether a fantastic book -- just what we all expect from O´Reilly.

Firewalls and Internet Security
$36.96

The classic tome of firewalls -- the most respected and referenced fireawll book available.  Problem is that it´s old and starting to show its age.  They say they´re working on a second edition, so it may be best to wait until that´s out.

Protecting Your Web Site w/ Firewalls
$56.00

From an Amazon.com reader review: "Goncalves puts an interesting and relevant spin on the world of firewalls and security. This is a must-buy for systems administrators as it brilliantly goes into the mind of the hacker. Others will also enjoy this book as it is easy to read and tries to minimize proprietary nomenclature associated with technical texts. You will find many chapters devoted to real-world solutions to emerging problems in Internet security."