A computer-implemented method and system is disclosed in which a network-based interaction environment includes a plurality of peer-to-peer nodes being able to communicate directly with each other using a peer-to-peer protocol and a peer-to-peer client application, the plurality of peer-to-peer nodes including a first peer-to-peer client and a second peer-to-peer client, a first peer-to-peer client application running on the first peer-to-peer client to maintain persistent buddy information on the first peer-to-peer client, the persistent buddy information including a buddy list identifying trusted peer-to-peer nodes of the plurality of peer-to-peer nodes, and a second peer-to-peer client application running on the second peer-to-peer client to maintain persistent reputation information on the second peer-to-peer client, the persistent reputation information including information related to the reputation of the first peer-to-peer client in the network-based interaction environment.