Scalable Security Mechanisms for the Internet

The design principle of restricting local autonomy only where necessary for global robustness has led to a scalable Internet. Unfortunately, this scalability and capacity for distributed control has not been achieved in the mechanisms for specifying and enforcing security policies. The STRONGMAN system described in this paper demonstrates three new approaches to providing efficient local policy enforcement complying with global security policies. First is the use of a compliance checker to provide great local autonomy within the constraints of a global security policy. Second is a mechanism to compose policy rules into a coherent enforceable set, e.g., at the boundaries of two locally autonomous application domains. Third is the "lazy instantiation" of policies to reduce the amount of state enforcement points need to maintain. We demonstrate the use of these approaches in the design, implementation and measurements of a distributed firewall.