Cyber-terrorism and corporate espionage are increasingly common and devastating threats, making trained network security professionals more important than ever. This timely text helps readers gain the knowledge and skills to protect networks using the tools and techniques of an ethical hacker. The authors begin by exploring the concept of ethical hacking and its practitioners, explaining their importance in protecting corporate and government data from cyber attacks. The text then provides an in-depth guide to performing security testing against computer networks, covering current tools and penetration testing methodologies. Updated for today’s cyber security environment, the Third Edition of this trusted text features new computer security resources, coverage of emerging vulnerabilities and innovative methods to protect networks, a new discussion of mobile security, and information on current federal and state computer crime laws, including penalties for illegal computer hacking.