This book is written for system administrators who need to know how to keep their systems secure from unauthorized use. Anonymous author takes the view of a hacker on various systems, focusing on how the system can be cracked and how you can secure the vulnerable areas. This book makes it clear from the beginning that you can not rely on commercial software for security. Rather than simply cataloging areas of risk and show how the various deficiencies can be exploited, the author makes every effort to show how security holes can be avoided and corrected saying. Maximum Security of your software to avoid and then details of the security tools that are invaluable, providing the URL required to obtain them.