This paper introduces the concept of a User Programmable Virtualized Network, which allows networks to deliver application specific services using network element components that developers can program as part of a users application. The use of special tokens in data or control packets is the basis of a practical, yet powerful security and AAA framework. This framework allows for implementations with a low footprint that can operate in a multi domain network operator environment. We demonstrate the ease with which one can build applications and address networking problems as they appear for example in sensor networks. © 2006 IEEE.