AbstractThe Internet is an open network where all traffic is subject to interception by malicious outsiders. TUOMAS AURA and DIETER GOLLMANN overview the current major threats and security solutions for communication over the Internet. They note that the lack of satisfactory authentication infrastructures and guaranteed quality of service remain the main impediments for secure communication. Continuous evolution of the protection mechanisms, developer skills, and user culture are necessary to stay on track with the progress in communication technology. Copyright © 2001 John Wiley & Sons, Ltd.