This book discusses risk analysis, the impact of security on performance, and how much protection is enough. There is a model system to illustrate the scope of security and information integrity, a survey of commercially available security products, discussion of proven methods for preventing unauthorized access, and explanation of how to deal effectively with worms and viruses. The book is divided into the following chapters: (1) Managing Network Security; (2) A Management Model for Network Security; (3) The OSI (Open System Interconnection) Security Architecture; (4) Recognizing Security Risks; (5) Encryption as a Security Mechanism; (6) Methods for Preventing Unauthorized Access; (7) Dealing with Worms and Viruses; (8) Micros, Minis, and Mainframes; (9) A Survey of Security Products; and (10) How Much Protection is Enough? There are footnotes accompanying each of the first nine chapters; a Network Security Checklist follows the last chapter. Glossary, list of products and company names which may be protected by trademark laws, and an index