In this paper, we present a multi-agent system implementing a fully distributed Social Network System supporting user profiles as FOAF profiles. This system is built around the idea that users should be the sole owners of the information they provide (either consciously or unconsciously) and addresses privacy issues by design, also minimizing the amount of information users have to disclose in order to make new friends. Users are represented by agents that both mediate access to private data and proactively negotiate with other agents in order to extend their user's social network. We also present the distributed connection discovery algorithm used by the agents and detail the representation of data in the users' profiles used to support the algorithm. The design is rather agnostic about the layer responsible for the communication technology; here we present a possible implementation on the top of the HDS software framework. Keywords; Middleware for distributed social systems...