Rick Cook
FIREWALLS AND INTERNET SECURITY: REPELLING THE WILY HACKER, William R. Cheswick and Steven M. Bellovin Addison-Wesley Professional Computing Series, ISBN 0-201-63357-4, $26.95
Forget The Silence of the Lambs. This is the book that will keep system administrators sleepless and shivering. While it wasn't intended as a compendium of computer-user horror stories, once you finish it, you will never look at the sendmail program in quite the same way again.
This is an encyclopedia of computer cracking via a network. It is neither exhaustive nor sufficiently detailed to be of much use to the would-be digital criminals of the world (who, as the authors point out, have better sources of information), but it is invaluable to those who want to foil th
em. Ostensibly, the audience is system administrators for Unix sites connected to the Internet. The focus is on Unix, as the mother tongue of the Internet, and the authors assume a fair level of Unix literacy. However, much of what they have to say applies to any network, and much more is applicable to NetWare, DOS, and Windows.
The basis of a safe connection, according to the authors, is a firewall, a computer system that sits between the Internet and your LAN, acting as an active gateway to keep the bad guys away from your goodies. However, bringing in your network connections through a separate system and calling it a firewall isn't enough. Creating a true firewall means limiting what that system will pass along to other systems, what an outsider can do with it, and how to ensure that you can keep track of who is trying to do what. Sometimes creating a firewall means creating a fool's paradise, where the crackers can bask in the delusion they have penetrated the system as they are being hunted down.
Chapter 10, ``An Evening with Berferd,'' includes a detailed account of a persistent attempt to crack the AT&T Internet gateway that the authors are responsible for. It shows how a determined attack proceeded and was defeated. The account is also a wry comment on the nature of modern Internet culture and computer criminals. The crackers were a group of Dutch teenagers who were beyond legal reach, because cracking was not then a crime in the Netherlands. When the law failed, someone from AT&T called the mother of one of the ring members. The cracking attempts dropped off sharply
A useful appendix provides sources of information on building firewalls, network management and monitoring tools, auditing software, and cryptographic software. A 20-page bibliography and a checklist of security holes round out the book.
The book deals with serious business, but through it all, the authors maintain a sense of humor, sprinkling the text with quotes from Juvenal to Tolkien to E. E. ``Doc'' Smith.
Rick Cook writes about computers but occasionally turns his hand to science fiction. You can contact him on BIX as ``rcook.''
Securing Your Internet Connection
