—The central paradigm of today’s successful Internet is to keep the network core simple and move complexity towards the network end points. Unfortunately, this very paradigm limits network management and control capabilities, and creates opportunities for attacks such as worms, viruses, and spam that often seriously disrupt and degrade Internet and user performance. The thrust of this paper is that such problems cannot be effectively solved unless a paradigm shift is adopted. Towards a more secure and manageable Internet, we propose “virtualization” of the Internet, by carefully balancing its scalability and programmability properties. Our objective is to provide a programmable virtual Internet to users and to let them manage, control, and optimize it based on their individual needs.