Now the server code for TDV is up. You can get both the executable for the server and the source code. https://github.com/munawarb/Three-D-Velocity
Also, you can connect to the server now using the latest version of the game. Please be mindful that it's been a long, long time since I've tested the server, so it's bound to be unstable in places, especially since I had to remove the code for add-ons and things since this was commercial only. So as you find issues, post them on the issues page and I'll release updates to the server code as time permits
Also, the server is under the same license as the rest of the source code. Feel free to reuse it, but make clear note how you modified the server code and make the modifications freely available.
I hope releasing the server code will show many of you how servers are written. I wrote this thing completely from scratch so there are no third-party libraries to contend with here.
I hope you have fun!