This book is the definitive guide on the OSSEC Host-based Intrusion Detection system and frankly, to really use OSSEC you are going to need a definitive guide. Documentation has been available since the start of the OSSEC project but, due to time constraints, no formal book has been created to outline the various features and functions of the OSSEC product. This has left very important and powerful features of the product undocumented... until now! The book you are holding will show you how to install and configure OSSEC on the operating system of your choice and provide detailed examples to help prevent and mitigate attacks on your systems. OSSEC determines if a host has been compromised in this manner by taking the equivalent of a picture of the host machine in its original, unaltered state. This "picture" captures the most relevant information about that machine"s configuration. OSSEC saves this "picture" and then constantly compares it to the current state of that machine...