- Open Transmission, go to Preferences >> Network and enter a number for the port. It is recommended you pick a random number between 49152 and 65535. Let's use 50001 for now. Then quit Transmission.
- Open System Prefs >> Sharing >> Firewall. Click "New." In the "Port Name" pop-up menu, select Other, and fill in the settings as follows:
- TCP Port Number(s): the port you chose in step 1 - eg 50001.
- UDP Port Number(s): the port you chose in step 1 - eg 50001.
- Description: Transmission
- Click OK.
NB: To disable the firewall, click Stop.