SIM SKUNK WORKS, after months of works, is proud to present the skunkNET, the SSW multiplayer environment.
All you need to know is in the skunkNET site
http://www.simskunkworks.com/skunkNET
However here a little abstract on what skunkNET is below:

skunkNET is an high performance peer-to-peer multiplayer system for Lockheed Martin’s Prepar3D and Microsoft’s Flight Simulator X (WIP for FSX).

It has been developed by Sim Skunk Works with the specific goal of providing a multiplayer environment for formation flight and combat simulation.

It incorporates several new technologies, which have been developed to provide a smooth flight, without sudden lags or jumps caused by bad or slow internet connections. A Kalman filter is used to estimate the airplane position and the network latency each frame, and a new control system is used to provide smooth, jitterless airplane movement in the air.

Thanks to a scaling method, skunkNET bandwidth consumption is extremely low. Data rates are decreased with relative distance, so that airplanes far away have very little effect on your connection speed.

skunkNET is completely free, and is available 24/7 on Sim Skunk Works server. A simple registration is required to receive a user ID that will allow you to connect to the skunkNET network and use skunkNET with your friends for formation flight. With skunkNET's account, you will be able to connect to vACMI, Sim Skunk Works weapon engine.

Together, skunkNET and vACMI provide the ultimate multiplayer combat flight simulation for P3D/FSX. You will be able to use your airplanes to shoot missiles, use guns, and drop bombs, causing real damage to other airplane and ground targets. Such targets can be both real players, connected to skunkNET, or AI objects, providing a full combat simulation.