CnCNet is a community built open source tool created to connect the LAN lobbies of classic Command & Conquer games allowing internet games without any form of registration.
Version 3 has just been released which boasts improved performance and less lag due to its unique client-host model as opposed to the Peer-2-Peer model of the official online play. Not only that but the servers are located in both USA and UK for minimum latency.
CnCNet now fully supports all classic C&C games, yes that means Command & Conquer (Covert Operations), Red Alert (Counterstrike, Aftermath), Tiberian Sun (Firestorm) and a newcomer Red Alert 2 (Yuri's Revenge).