This document discusses proactive population-risk based defense against denial of cyber-physical service attacks. It proposes using test packets to test network state and rules across switches to detect faults. The goals are to augment human debugging, reduce downtime, and save money. Related work discussed network tomography using end-to-end measurements to identify lossy links. Striped unicast probes were also explored to infer link-level loss rates. The algorithm aims to generate test packets that exercise every rule on each switch to detect faults with a minimum number of packets.