First, we wish to show that this strategy is useful. That is, a firewall, if properly deployed against the expected threats, will provide an organization with greatly increased security. Second, we wish to show that such gateways are necessary, and that there is a real threat to be dealt with. This book is written primarily for the network administrator who must protect an organization from unhindered exposure to the Internet. The typical reader should have a background in system administration and networking.
Some portions necessarily get intensely technical.
A number of chapters are of more general interest. Readers with a casual interest can safely skip the tough stuff and still enjoy the rest of the book. We also hope that system and network designers will read the book. Many of the problems we discuss are the direct result of a lack of security-conscious design. We hope that newer protocols and systems will be inherently more secure.