Linux Firewalls: Attack Detection and Response with iptables, psad, and fwsnort

Some useful reference papers, some of which were cited within the book, can be found on these sites:

"Help Defeat Denial of Service Attacks: Step-by-Step": http://www.sans.org/dosstep/index.php

"Internet Firewalls Frequently Asked Questions": http://www.interhack.net/pubs/fwfaq/

"TCP SYN Flooding and IP Spoofing Attacks" (CERT Advisory CA-96.21): http://www.cert.org/advisories/CA-1996-21.html

"TCP/UDP Service Port Numbers" (IANA): http://www.iana.org/assignments/port-numbers

"UDP Port Denial of Service Attack" (CERT Advisory CA-1996.01): http://www.cert.org/advisories/CA-1996-01.html