Wireless communications have become indispensable part of our lives. The book deals with the security of such wireless communication. The technological background of these applications have been presented in detail. Special emphasis has been laid on the IEEE 802.11x-standards that have been developed for this technology. A major part of the book is devoted to security risks, encryption and authentication. Checklists have been provided to help IT administrators and security officers to achieve the maximum possible security in their installations, when using wireless technology. This is the second edition of the book. The updates include the latest the IEEE 802.11-standard, an updated chapter on PDA, the increased relevance of smart phones and tablets, widespread use of WLAN with increased security risks.