How to Use This Book

The information in this book follows a quick-reference format. If you know what firewall feature or technology you want to use, you can turn right to the section that deals with it. The main sections are numbered with a quick-reference index that shows both the chapter and the section (for example, 3-3 is Chapter 3, section 3). You'll also find shaded index tabs on each page, listing the section number.

Feature Description

Each major section begins with a detailed explanation of or a bulleted list of quick facts about the feature. Refer to this information to quickly learn or review how the feature works.

Configuration Steps

Each feature that is covered in a section includes the required and optional commands used for common configuration. The difference is that the configuration steps are presented in an outline format. If you follow the outline, you can configure a complex feature or technology. If you find that you don't need a certain feature option, skip over that level in the outline.

In some sections, you'll also find that each step in a configuration outline presents the commands from multiple firewall platforms in an adjacent manner. You can stay in the same configuration section no matter what type or model of firewall you're dealing with.

Sample Configurations

Each section includes an example of how to implement the commands and their options. Examples occur within the configuration steps, as well as at the end of a main section. I have tried to present the examples with the commands listed in the order you would actually enter them to follow the outline. Many times, it is more difficult to study and understand a configuration example from an actual firewall because the commands are displayed in a predefined ordernot in the order you entered them. Where possible, the examples have also been trimmed to show only the commands presented in the section (where possible).

Displaying Information About a Feature

Each section includes plenty of information about the commands you can use to show information about that firewall feature. I have tried to provide examples of this output to help you interpret the same results on your firewall.