In hybrid wireless networks (HWNs), where the fixed cellular network infrastructure is utilized to provide enhanced network coverage and communication performance for nodes in mobile ad-hoc networks, the selection of the gateway for each node towards the external network needs to be based on accurate and timely network performance perceived by each mobile node. Continuously monitoring these performance metrics by each individual node, however, would incur prohibitively high communication and processing overhead. In this paper, we propose a distributed network probing mechanism, called CoPing, that utilizes the cooperation among the nodes in the measurement process of path performance in MANETs towards the gateways of HWNs. In our approach, each node makes use of the end-to-end performance probing results measured by other nodes to estimate its own performance to the gateways in a fully distributed manner. Furthermore, the distributed process does not require explicit structure and coordination between the nodes, making it ideal for highly dynamic networking environments. Through the combination of analysis and experimental evaluation, we show our cooperative probing mechanism can achieve accurate and efficient path performance results for gateway selection in HWNs. © 2013 IFIP.