Peer-to-peer system decentralization complicates performance monitoring-and real-time monitoring is particularly challenging. We discuss our experience with monitoring the Peer Name Resolution Protocol (PNRP), a peer-to-peer name resolution/routing protocol and overlay deployed over the Internet. We must collect accurate performance data without adding traffic overhead. Unfortunately, no central node has sufficient monitoring information, and scalability and privacy concerns make it impractical to collect reliable real-time data from active client nodes. Our method obtains information from lightweight nodes (Weather Stations) actively deployed on the P2P network and themselves forming a private P2P overlay. We monitor the overall performance of the PNRP protocol on the Internet and produce timely reports supporting network management, security alerting, and system maintenance.