This book constitutes the thoroughly refereed post-proceedings of the International Conference on Information Networking, ICOIN 2003, held at Cheju Island, Korea in February 2003. The 100 revised full papers presented were carefully selected during two rounds of reviewing and revision. The papers are organized in topical sections on high-speed network technologies, enhanced Internet protocols, QoS in the Internet, mobile Internet, network security, network management, and network performance.