This book identifies and explains all the modern standardized methods of achieving network security in both TCP/IP and OSI environments -- with a focus on inter-system, as opposed to intra-system, security functions. Part I is a technical tutorial introduction to computer network security; Part II describes security standards, protocols and techniques. Covers such topics as cryptography, authentication, access control, and non-repudiation; describes a wide range of standard security protocols and techniques, drawn from international, national, government, and Internet standards; and considers areas such as network and transport layer security, local area network security, security management, and security for applications such as electronic mail, directory services, EDI, and banking. For anyone required to design, develop, implement, market, or procure products based on specific network security standards.