This document presents a distributed algorithm called DAWN to detect wormhole attacks in wireless network coding systems. The algorithm has two phases: 1) a detection phase where each node uses the expected transmission count (ETX) metric to detect if any attackers exist, and 2) a reporting phase where detected attackers are reported to other nodes. ETX represents the number of transmissions needed for a packet to be received and can reveal the network topology. DAWN examines the order nodes receive packets and their ETX values to identify attackers. It signatures reports to prevent manipulation and distributes the workload of detection across all nodes. The algorithm successfully detects wormhole attacks with high rates while imposing low computation and communication overhead.