This is an authoritative security handbook from the CERT Coordination Center, the oldest computer security response group in existence and part of the SEI Institute, and Carnegie Mellon University. With a practical, stepwise approach, the book shows students how to protect systems and networks against malicious and inadvertent compromise. The book is divided into two main parts, the first dealing with hardening and securing your system-preventing problems. The second part covers intrusion detection and response, recognizing that even the most secure networks and systems cannot protect against every conceivable threat. The practices selected for the book are based on CERT's extensive data on security breaches and vulnerabilities, providing an authoritative view of the most common problems that students will face as a system and network administrator.