The reddit thread raises a good question I have often wondered. What is my best option for an application level firewall? I want to deny network connections by default and specifically enable who can speak to the outside world.

OpenSnitch[1] is mentioned[2] in the reddit thread and was most recently featured on HN last year[3].

[1] https://github.com/evilsocket/opensnitch

[2] https://old.reddit.com/r/linux/comments/od3h8b/audacity_may_...

[3] https://news.ycombinator.com/item?id=22206116