Help Net Security published a review on the book "Linux Firewalls: Attack Detection and Response with iptables, psad and fwsnort"

There's no need to emphasize the significance of a firewall in the overall security architecture. Countless security professionals turn to Linux when it comes to deploying firewalls using open source tools and Michael Rash, the author of this book, is one of them.

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