This book constitutes the thoroughly refereed post-proceedings of the IFIP TC6 5th International Workshop on Active Networks, IWAN 2003, held in Kyoto, Japan, in December 2003.

The 24 revised full papers presented were carefully reviewed and selected from 73 submissions. The papers are organized in topical sections on high performance and network processors, high-level active network applications, low-level active network applications, self-organization of active services, experiences with service engineering for active networks, management in active networks, and selected topics in active networks.