Building Internet Firewalls: Internet and Web Security

Firewalls and Internet Security: Repelling the Wily Hacker (2nd Edition)

Firewalls For Dummies

Firewall Fundamentals

TCP/IP Network Administration (3rd Edition; O'Reilly Networking)

Linux Security Cookbook

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

Blue Team Handbook: Incident Response Edition: A condensed field guide for the Cyber Security Incident Responder.

Rtfm: Red Team Field Manual

The Network Security Test Lab: A Step-by-Step Guide

Network Warrior: Everything You Need to Know That Wasn't on the CCNA Exam