Once your security is breached, everyone will ask the same question: nowwhat? Answering this question has cost companies hundreds of thousands ofdollars in incident response and computer forensics fees. This book reducesthe investigative workload of computer security incident response teams(CSIRT) by posturing organizations for incident response success.Firewalls can fail. Intrusion-detection systems can be bypassed. Networkmonitors can be overloaded. These are the alarming but true facts aboutnetwork security. In fact, too often, security administrators' tools can serve asgateways into the very networks they are defending.Now, a novel approach to network monitoring seeks to overcome theselimitations by providing dynamic information about the vulnerability of allparts of a network. Called network security monitoring (NSM), it draws on acombination of auditing, vulnerability assessment, intrusion detection andprevention, and incident response for the most comprehensive approach tonetwork security yet. By focusing on case studies and the application of opensourcetools, the author helps readers gain hands-on knowledge of how tobetter defend networks and how to mitigate damage from security incidents.