I was trying to remote control a plexamp install on a linux server from my phone. Worked with my firewall (ufw) disabled but I was looking for the right port to whitelist and couldn’t find it anywhere. This is how I found it:
$ sudo netstat -tunlp | grep LISTEN
After trying a few wrong guesses, the answer was:
tcp6 0 0 :::32500 :::* LISTEN 3423/app.asar --no-
So added it:
sudo ufw allow from 192.168.0.0/16 to any port 32500
And now it works! Hope that helps someone.
Side note, I am doing this because there is no plexamp for roku. Luckily I already have a linux server in my TV console.