ABSTRACT
Protecting against cyber attacks on websites, communications systems, databases, and key transportation and other infrastructures presents a major problem to the United States and other governments as well as to the business world and private citizens. The attacks can come from a variety of sources: terrorists, other governments or persons working on their behalf, criminals, or hackers who operate from an ideological/ political motivation or just for the challenge of breaking through the defenses of sensitive systems. Because of the nature of the Internet, it is usually difcult to quickly determine the source of the cyber attack.
