[spl757]

I usually have small mini-pc with at least two ethernet ports and configure it as a transparent bridge sitting between my desktop and the router/switch. Give the bridge a local IP, set up some packet inspection stuff, and you can easily monitor anything and everything going in and out. It's not all I use, but it's one part.

I also run ai models locally and like to verify that things aren't talking to the internet if they aren't supposed to be.