Little Snitch for Linux https://obdev.at/products/littlesnitch-linux/index.html Every time an application on your computer opens a network connection, it does so quietly, without asking. Little Snitch for Linux makes that activity visible and gives you the option to do something about it. You can see exactly which applications are talking to which servers, block the ones you didn't invite, and keep an eye on traffic history and data volumes over time https://github.com/obdev/littlesnitch-linux
@nixCraft And OpenSnitch makes things actually have to get permission to do it. (You can set it to always allow/reject/drop or to do so for an interval.)
I've found a surprising number of things making connections they really shouldn't be. One that scares me is many thumbnail engines will open URLs inside things... (They're not browsers. They're not up on the latest security issues/etc, they don't have ad blockers or privacy guards, etc etc. They should not be allowed to go online ever!)
Kind of bugs me how many things just don't even try to hide telemetries that the user doesn't get to opt out of. Many game engines are bad about this for example. They just phone home and there is no setting in the game to turn it off.
