With our modern society' s increased dependence on information technology and communication networks, the subject of network security is developing into a crucial base technology and most people working in the networking and information technology business will need to know the basics of fixed and wireless network security. This book gives a firm introduction into the field covering the fundamentals of data security technology and explaining in-depth how they are applied in communication networks.This book: approaches network security from the wireless as well as the computer networking side; concentrates on the core networking issues (first 4 layers up to the transport layer); helps the reader to understand the risks of a lack of security in a network & how to prevent it; brings security in networks up to date by covering wireless and mobile security issues; includes security issues around hot topics such as wireless LANs (e.g. 802.11), AAA (Authentication, authorization, and accounting), and Mobile IP; illustrates complicated security concepts with exercises and features an extensive glossary.It serves as an essential reference tool for graduate students of computer science, electrical engineering and telecommunications who need to learn the basics of network security. Also, professionals working in data- & telecommunications will also benefit from the book as it gives a self-contained introduction to the basics of network security: network managers, engineers, IT managers.