RakNet

RakNet is networking middleware developed by Oculus VR, Inc. for use in the video game industry. RakNet was originally authored by Jenkins Software LLC.
Overview.
RakNet is a C++ class library that provides UDP and reliable TCP transport. It contains several core systems that rely on the transport layer: object replication; Remote procedure call in C++ using Boost C++ Libraries; VoIP supporting FMOD, DirectSound, and PortAudio; NAT traversal; and Patch.
Its source was available without charge for games grossing under $100,000 allowing use by developers of indie or free/open source games.
On July 7, 2014, RakNet was bought by Oculus VR who released the source code for PCs, under the BSD licence with a patent granting license.