I am looking at the cube2 engine (via sauerbraten) and while trying things out in Ubuntu I noticed the error: “could not create server host”. After doing a bunch of debugging (good thing the code comes with it) I found that the linux_server process was ALREADY running. To check you can try a few things:
1. from a command prompt type:
That will show all the ports currently open. Scroll up to the top of the output and check for UDP (datagram) ports 28785 and 28786. If they exist then something is already using the ports that Sauerbraten requires (those default ports likely can be changed via command line params or config files in sauerbraten).
2. Open the Graphical System Monitor (get to know this application well.. its like the Windows Task Manager) which in Ubuntu is under: System / Admin / System Monitor and check for a process named: linux_server or native_server. You can right click on it and end or kill it if you want to start a new server.
Hope this helps save someone time.