Dan Barrett has been immersed in Internet technology since 1985. Currently working as a software engineer, Dan has also been a heavy metal singer, Unix system administrator, university lecturer, web designer, and humorist. He is the author of O'Reilly's Linux Pocket Guide, and he is the coauthor of Linux Security Cookbook, and SSH, The Secure Shell: The Definitive Guide. He also writes monthly columns for Compute! and Keyboard Magazine, and articles for the O'Reilly Network. Richard E. Silverman has a B.A. in computer science and an M.A. in pure mathematics. Richard has worked in the fields of networking, formal methods in software development, public-key infrastructure, routing security, and Unix systems administration. He is the co-author of SSH, The Secure Shell: The Definitive Guide. Robert G. Byrnes, Ph.D., has been hacking on Unix systems for twenty years, and has been involved with security issues since the original Internet worm was launched from Cornell University, while he was a graduate student and system administrator. He is currently a software engineer at Curl Corporation, and has worked in the fields of networking, telecommunications, distributed computing, financial technology, and condensed matter physics.