Automated Synthesis of Verified Firewalls

We demonstrate correct-by-construction firewalls—stateful packet filters for TCP/IP packets—using the Fiat synthesis library [3]. We present a general DSL for specifying their behavior independent of algorithmic implementation. We outline the design of a verified compiler in Coq, detail a few verified efficiency optimizations, and show how the compiler can easily be extended to support custom optimizations for user-defined policies.