There is not a prebuilt one, here is what I did:
- Find the TNetServer.zip file that came with the asset store package and extract it somewhere.
- In the place where you extracted it, Create an "Assets" folder, and within that create a "TNet" folder.
- Copy the folders "Common" and "Server" from the asset store package into the TNet folder you just created.
- Open up TNServer.sln with MonoDevelop, ensure you are in "Release" mode and hit build.
As with any mono application if you want to run it when not using the MonoDevelop IDE, cd to the file in the Terminal and type "mono yourApp.exe".
Also note that MonoDevelop doesn't block when it hit's a "ReadLine" or "ReadKey", so if you try testing it in the IDE it will hit an infinite loop where the server is waiting for you to press q to quit.