In this paper, we evaluate the feasibility of multiagent control of resources to be shared in user networks. A user network is totally controlled by the users, both at application and transport level. One of the possible applications in these networks is peer-to-peer (P2P) file exchange sharing the "external" access to the Internet (set of links between the user network and the Internet). If a node cannot serve its demand with its own external link, it requests help from another node via the high-bandwidth internal user network. We model user nodes as agents to simulate and to evaluate a new agent-based distributed control scheme. The simulation results in this paper confirm that it is possible to improve resource sharing in user networks using agents that take decisions autonomously, from local information, and check that file exchange services offered to neighbour nodes do not surpass appropriate credit limits.