If there's a shortcoming to this book, it's its lack of coverage of the turnkey firewall products that are becoming popular among home and small-office users. Emphasis here is on more complicated network defenses that require careful design and setup--both design and implementation are the order of the day here. The authors carefully enumerate the threats they see in various situations, go into some detail on how those threats manifest themselves, and explain what configuration changes you can make to your perimeter defenses to repulse those threats. Plenty of illustrations make points about good and bad security strategies (you want to put the routers here and here, not here or here). You'll learn a lot by reading this book from cover to cover, no matter how much experience you have. --David Wall

Topics covered: Means of protecting private networks from external security threats. The authors go into detail on attackers' means of exploiting security holes in common Internet services, and show how to plug those holes or at least limit the damage that can be done through them. With coverage of Unix, Linux, and Windows NT, the authors detail their philosophies of firewall design and general security policy.