Gnutella2

Gnutella2, often referred to as G2, is a peer-to-peer protocol developed mainly by Michael Stokes and released in 2002. While inspired by the gnutella protocol, G2 shares little of its design with the exception of its connection handshake and download mechanics. It adopts an extensible binary packet format and an entirely new search algorithm. Furthermore, it has a slightly different network topology and an improved metadata system which helps effectively to reduce fake files, viruses (etc.) on the network.