This book presents the need for intrusion detection system as it has become an essential concern with the growing use of internet and increased network attacks such as virus, Trojan horse, worms and creative hackers. In addition, the basic details about the historic origin of IDS, the types of IDS, their deployment schemes and general architecture are considered. IDS using various machine learning techniques like fuzzy logic, genetic algorithm, neural network, decision tree etc are discussed and their pros and cons are discussed. Another potential approach is ensemble learning, which have...