What Ports do you need to forward to host an adhoc server?

[AdamN]

Adhoc Server only use port 27312
But adhoc server only used to create the group of players, while each players communicate directly (ppsspp to ppsspp) without using adhoc server during multiplayer gameplay, so you will need to forward each port used by the game also, and these ports are varies depend on the game, which is why you need DMZ (or VPN such as hamachi where all connections will be tunneled to a static port)