I have an old Ubuntu server (13.04), and want to open a port for this online game server style software for a mate. I need a port open, and to tell it that port (I know how to tell the game that port).
For the sake of argument, let the port I want to open be 12345.
How do I do such, with no access to a GUI, only a Bash shell. Both how to open the port, and how to fiddle with the firewall so that port is visible to the world.
EDIT: I can port forward it internally (iptables esque), but I don't know what firewalling software I have installed. Is there an easy way to find that out? Also, how do I port forward the router as well, all from the terminal. Sorry for the earlier lack of detail