I followed this guide for setting up the gufw firewall: https://wiki.ubuntu.com/BasicSecurity/Firewall. However, after setting up the Transmission rules, Transmission doesn’t work, nor any other torrent app.
sudo ufw allow out 51413/tcp
sudo ufw allow out 51413/udp
sudo ufw allow out 6969/tcp
I followed this guide for allowing the 51413 port: https://portforward.com/linksys/e900/, yet Transmission fails to download anything. What am I missing guys?
Hi @vr_anticipator,
do the settings match in both apps (firewall and Transmission) ?, did you apply the same ports in both?:
Yes. The same port is in both Transmission and gufw. Also, the rest of the settings are the same as the screenshot above.
Do you have “Deny” set on incoming?. 
Isn’t that how it is supposed to be: deny on incoming and only allow incoming from certain ports?
I would first try “allow” and see if that is what is stopping it?.
When I allow outgoing, it is working.
Hi @vr_anticipator,
I would assume that because Transmission uses two-way-traffic, you will have to allow it?. You are uploading as well as downloading so I suppose the app will only allow a download when it is also allowed to upload?.
I suppose that is true 
Can I download torrents with disabled upnp and nat? Thanks for all your help
I don't see why not?. I suppose it depends on how you have your home network set up?.
I would also choose Deluge over Transmission (personal preference!):
To install via the terminal (Ctrl + Alt + t) and compare:
sudo apt-get install deluge
