'Linux iptables Pocket Reference' is an important and sorely needed reference to iptables, the interface to the Linux packetfilter used by System Admins to create firewalls, NAT routers, transparent proxies, and other 'magical' network devices. While not a tutorial, it offers good advice for those with a grasp of basic networking concepts, and a good notion of what a firewall is and what it is used for, in a dense and concise format. Sufficiently detailed information about the protocols involved obviate the need to keep additional references at hand, and make the work relatively self-contained. This should not be the first book you read about firewalls or tcp/ip, but if you are a networking professional, a technically oriented user, or just interested in creating special purpose network devices, this book belongs in your library. Those familiar with iptables will especially appreciate the lucid description of packet flow through the tables and chains, and the supporting diagrams ... they alone are worth the price of purchase.
If you have need for a book on the topic, you will not be disappointed with this one.