http://www.jenkinssoftware.com/index.html
https://github.com/OculusVR/RakNet
It's pretty widely used and quite powerful AFAIK, thus this should be interesting for FOSS game development.
http://www.oculusvr.com/blog/announcing ... 14-awards/
For those unfamiliar with RakNet, it is a comprehensive C++ game networking engine designed for ease of use and performance. The tech is tuned for cross-platform, high-performance applications that operate across a wide variety of network types. Key features include object replication, remote procedure calls, patching, secure connections, voice chat, and real-time SQL logging. The technology has been licensed by thousands of indie developers, as well as companies like Unity, Havok, Mojang, Maxis and Sony Online Entertainment.