This paper focuses on defending against compromised nodes’ dropping of legitimate reports and investigates the misbehavior of a maliciously packet-dropping node in sensor networks. We present a resilient packet-forwarding scheme using Neighbor Watch System (NWS), specifically designed for hop-by-hop reliable delivery in face of malicious nodes that drop relaying packets, as well as faulty nodes that fail to relay packets. Unlike previous work with multipath data forwarding, our scheme basically employs single-path data forwarding, which consumes less power than multipath schemes. As the packet is forwarded along the single-path toward the base station, our scheme, however, converts into multipath data forwarding at the location where NWS detects relaying nodes’ misbehavior. Simulation experiments show that, with the help of NWS, our forwarding scheme achieves a high success ratio in face of a large number of packet-dropping nodes, and effectively adjusts its forwarding style, de...