Who should read this book? Although the book is aimed primarily at those who need to build firewalls, large parts of it are appropriate for everyone who is concerned about Internet security. This list tells you what sections are particularly applicable to you:
You should read the entire book. As we've mentioned, a thorough knowledge of TCP/IP is essential for understanding and building firewalls. If you are not already familiar with TCP/IP, you should read at least Appendix C right now.
 And we strongly recommend that you read all of Craig Hunt's excellent book, TCP/IP Network Administration (O'Reilly & Associates, 1992), from which the appendix is adapted.
You should at least read Part I of the book. The chapters in Part I will introduce you to the various types of Internet threats, services, and security approaches and strategies. They will also introduce you to firewalls and describe what they can and cannot do to enforce Internet security. You should also read Chapter 4, which provides an overview of firewall design. In addition, Appendix A will tell you where to go for more information and resources.
You should read all of the chapters we've cited for the managers in the previous category. In addition, you should read Part III, which explains the kinds of issues that may arise at your site over time, e.g., how to develop a security policy, keep up to date, and react if someone attacks your site.