Essential information for anyone wanting to protect Internet-connected computers from unauthorised access. Includes:

* thorough discussion of security-related aspects of TCP/IP;
* step-by-step plans for setting up firewalls;
* hacking and monitoring tools the authors have built to rigorously test and maintain firewalls;
* pointers to public domain security tools on the net;
* first-hand step-by-step accounts of battles with the "Berferd" hackers; and
* practical discussions of the legal aspects of security.