After giving us a background of network security, the book moves on to explain the basic technologies we will work with, namely netfilter, iproute2, NAT and l7-filter. These form the crux of building Linux firewalls and QOS. The later part of the book covers 5 real-world networks for which we design the security policies, build the firewall, setup the script, and verify our installation. These comprehensive set of set up scripts and set up guidelines to create firewall protection for various specific usage scenarios are unique and set this book apart.

在介绍了网络安全的背景之后，本书接着解释了我们将要使用的基本技术，即netfilter、iproute2、NAT和l7-filter。这些构成了构建Linux防火墙和QOS的关键。本书的后半部分涵盖了5个真实世界的网络，我们为其设计安全策略，建立防火墙，设置脚本，并验证我们的安装。这些全面的设置脚本和设置指南，为各种特定的使用场景创建防火墙保护，是本书的独特之处，使本书与众不同。