Firewalls are among the best-known security tools in use today, and their critical role in information security continues to grow. However, firewalls are most effective when they are backed by effective security planning, a well-designed security policy, and when they work in concert with anti-virus software, intrusion detection systems, and other tools. This book aims to explore firewalls in the context of these other elements, providing readers with a solid, in-depth introduction to firewalls that focuses on both managerial and technical aspects of security. Coverage includes packet filtering, authentication, proxy servers, encryption, bastion hosts, virtual private networks (VPNs), log file maintenance, and intrusion detection systems. The second edition offers updated content and brand new material, from enhanced coverage of non-firewall subjects like information and network security to an all-new section dedicated to intrusion detection in the context of incident response.