This fully updated new edition explores the security issues, vulnerabilities and dangers encountered by the users of modern computing and communication devices, highlighting the need to develop improved algorithms, protocols, and best practices to enhance the security of public, private and enterprise systems alike. Features: introduces the fundamentals of traditional computer networks and the security threats they face; discusses the security challenges introduced by virtualization software, cloud computing and mobile systems; examines the security quagmire presented by the home computing environment; raises important legislative, legal, social, technical and ethical security issues, including the tension between the needs of individual privacy and collective security; provides both quickly workable and more thought-provoking exercises at the end of each chapter, with one chapter devoted entirely to lab exercises; supplies additional support material for instructors at an associated website.