Chapter 1. Introduction to Firewalls

In this chapter, we will introduce some firewalling and networking concepts in enough detail to provide a refresher to those who've encountered them already, but in as minimal a fashion as possible, since understanding networking concepts is not the focus of this book. We feel that some of these concepts are important, and that a broader picture of how these technologies are used and where they come from serves to better our understanding of the way in which IT works—however, for the reader who is challenged for time, we have tried, wherever possible, to provide italicized summaries of the knowledge that we feel is important to have about these concepts.

Don't worry if you don't understand all of the concepts we discuss—equally, readers more comfortable with networking concepts should be able to skip ahead. IPCop makes explicit understanding of many of these concepts irrelevant, as it attempts to make administration simple and automated wherever possible. However, if you do feel inclined to learn about these topics in more depth, the introduction given here and some of the URLs and links to other resources that we provide should hopefully be of use. Understanding networking, routing, and how some common protocols work, although not a requirement, will also help you immeasurably if you intend to keep working with systems such as IPCop on a regular basis.