To defend against computer and network attacks, multiple, complementary security devices such as intrusion detection systems (IDSs), and firewalls are widely deployed to monitor networks and hosts. These various IDSs will flag alerts when suspicious events are observed. This book is an edited volume by world class leaders within computer network and information security presented in an easy-to-follow style. It introduces defense alert systems against computer and network attacks. It also covers integrating intrusion alerts within security policy framework for intrusion response, related case studies and much more.