Introduction

The Internet can be a dangerous and costly place. Since its inception, there has been a consistent and steady rise in network and systems security incidents in every existing business and government sector. And, in a world where the number of computers and networks attached to the Internet grows by the hour, the number of potential attack targets has grown proportionally, and now includes a large concentration of home users who are experiencing "always on" broadband connectivity for the first time.

At first glance, the numbers related to Internet security breaches can be staggering, both in terms of sheer frequency and financial impact. Market researcher TruSecure estimates that losses from computer crime in 2003 could total over 2.8 billion. The Code Red worm in 2001 alone caused an estimated $2 billion in damages and cleanup costs. Shortly thereafter, the Nimda worm was unleashed, with estimates of over $2.5 billion in damage.

In the eighth annual CSI/FBI Computer Crime and Security Survey, 251 of 530 companies surveyed reported combined losses of nearly $202 million, most of which stemmed from proprietary information theft and Denial-of-Service attacks. A bright spot in the 2003 CSI/FBI report indicated that reported losses of the companies surveyed dropped for the first time since the initial 1995 survey. This drop in costs occurred even though the number of attempted attacks did not diminish. Could this savings be attributed to increased corporate vigilance and attention to network security?

Perhaps most troubling of these figures, however, is the fact...