Book Description: SATAN (Security Administrator's Tool for Analyzing Networks) is a powerful aid for system administrators. It performs "security audits," scanning host computers for security vulnerabilities caused by erroneous configurations or by known software errors in frequently used programs. SATAN is a particularly interesting piece of software because it uses the Web as its front end. This small book describes not only how to install and use SATAN, but also how to extend its modular structure to adapt it to local requirements and increase its knowledge of specific security vulnerabilities. It also discusses how you can defend your site against potential abuse by SATAN.