This practical guide to managing network security covers reliable methods for detecting network intruders, from using simple packet sniffers to more sophisticated IDS (Intrusion Detection Systems) applications and the GUI interfaces for managing them. A comprehensive resource for monitoring illegal entry attempts, Managing Security with Snort and IDS Tools provides step-by-step instructions on getting up and running with Snort 2.1, and how to shut down and secure workstations, servers, firewalls, routers, sensors and other network devices.;Managing Security with Snort and IDS Tools; About This Book; Assumptions This Book Makes; Chapter Synopsis; Conventions Used in This Book; Comments and Questions; Acknowledgments; Christopher Gerg; 1. Introduction; 1.2. Defense-in-Depth; 1.3. Detecting Intrusions (a Hierarchy of Approaches); 1.4. What Is NIDS (and What Is an Intrusion)?; 1.5. The Challenges of Network Intrusion Detection; 1.5.2. False Positives; 1.5.3. Missing Prerequisites; 1.5.4. Unrealistic Expectations; 1.6. Why Snort as an NIDS?; 1.7. Sites of Interest; 2. Network Traffic Analysis; 2.1.2. UDP; 2.1.3. IP; 2.1.4. ICMP.