Abstract. In unstructured peer-to-peer networks, as in real life, a good neighbourhood is not only crucial for a peaceful sleep, but also for an exchange of important gossips and for finding good service. This work investigates self-protection mechanisms based on reputation in unstructured peer-to-peer networks. We use a simple approach where each peer rates the service provided by others and exchanges the collected knowledge with its direct neighbours. Based on reputation values peers manage their connections to direct neighbours and make service provisioning decisions. To quantify the impact of our proposed scheme, we implement a simple protocol in a fully unstructured peer-to-peer network. We show that free riding and the impact of malicious peers trying to poison the network with bad files is minimised. Furthermore, we show that a good neighbourhood protects peers from selecting bad files, while free riders suffer in a bad neighbourhood of malicious peers.
Ivan Martinovic, Christof Leng, Frank A. Zdarsky,