From their Website
Open Fortress is a free Team Fortress 2 mod that introduces new gamemodes, weapons, characters, maps, and more to the world of TF2.
Open Fortress servers require 1 port to be open, the SourceTV port can also be opened for spectators.
| Port | default |
|---|---|
| Game/rcon | 27015 |
| SourceTV | 27020 |