In this paper we formulate the prevention of Denial of Service (DoS) attacks in wireless sensor networks as a repeated game between an intrusion detector and nodes of a sensor network, where some of these nodes act maliciously. We propose a protocol based on game theory which achieves the design objectives of truthfulness by recognizing the presence of nodes that agree to forward packets but fail to do so. This approach categorizes different nodes based upon their dynamically measured behavior. Through simulation we evaluate proposed protocol using packet throughput and the accuracy of misbehaving node detection.