The trend towards value-added Internet services causes network providers to deploy new network based quality-of-service and security services. Today, however, the customer has only limited means of controlling the service delivery. For example the network security guaranteed by virtual private network providers cannot be checked with a traditional static approach. This paper presents a novel approach for controlling new IP services using mobile code, and motivates the approach with two examples of new IP services proposed by the Internet engineering task force (IETF).