Linux Firewalls: Attack Detection and Response with iptables, psad, and fwsnort is a quite interesting book about iptables features to be configured as an UTM device through its integration with Snort specific iptables plugins for log correlation, traffic access control.
This book has many real examples and detailed configurations. I could not test those configurations in a lab so I cannot see them running, but expect this tool and its way to be configured evolve with time.
In my humble opinion, tools detailed in this book are useful for home usage and SOHO environments only able to afford free open source tools. For more exigent corporate environments, I feel this solutions loosely integrated, with a difficult maintenance if your network is big and heterogeneous and besides nowadays there are many commercial tools with a reduced price for almost every firm.
I felt more interesting explanations given by author for many networks attacks. Those explanations are very detailed but easily understandable. Nevertheless, most part of those attacks are known at the public domain for long time, so hardened security engineers won't learn anything new here.
Summarizing: This book is correct but only really useful for those who are making their first steps in security engineering world.