Building Internet Firewalls, 2nd Edition

Chapter 13. Internet Services and Firewalls

This chapter gives an overview of the issues involved in using Internet services through a firewall, including the risks involved in providing services and the attacks against them, ways of evaluating implementations, and ways of analyzing services that are not detailed in this book.

The remaining chapters in Part III describe the major Internet services: how they work, what their packet filtering and proxying characteristics are, what their security implications are with respect to firewalls, and how to make them work with a firewall. The purpose of these chapters is to give you the information that will help you decide which services to offer at your site and to help you configure these services so they are as safe and as functional as possible in your firewall environment. We occasionally mention things that are not, in fact, Internet services but are related protocols, languages, or APIs that are often used in the Internet context or confused with genuine Internet services.

These chapters are intended primarily as a reference; they’re not necessarily intended to be read in depth from start to finish, though you might learn a lot of interesting stuff by skimming this whole part of the book.

At this point, we assume that you are familiar with what the various Internet services are used for, and we concentrate on explaining how to provide those services through a firewall. For introductory information about what particular services are ...