Part II describes how to build firewalls, configure services to run with them, and maintain firewalls over time.

Chapter 4, Firewall Design , outlines the basic components and major architectures used in constructing firewalls -- dual-homed hosts, screened hosts, screened subnets, and variations on these basic architectures.

Chapter 5, Bastion Hosts , presents step-by-step instructions for how to design and build the bastion hosts used in many firewall configurations.

Chapter 6, Packet Filtering , describes how proxy clients and servers work, and how to use these systems in building a firewall.

Chapter 7, Proxy Systems , describes how packet filtering systems work and discusses what you can and can't accomplish with them in building a firewall.

Chapter 8, Configuring Internet Services , describes how to configure each major Internet service to run with a firewall.

Chapter 9, Two Sample Firewalls , presents two sample configurations for basic firewalls.

Chapter 10, Authentication and Inbound Services , discusses the problem of allowing users to access your systems from the Internet, and describes a variety of authentication strategies and products.