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
FYI, UI and client side is in Rust and open source but its core daemon on Linux is not. This app is from same authors who wrote macOS/OS X version. So use with caution as it is not 100% open source like many games you play on Linux.
@nixCraft OpenSnitch is open front to back.
Maybe not as nice but has been doing the job for years.
[edit : grammar]
opensnitch package versions - Repology

List of package versions for project opensnitch in all repositories

@regendans @squalouJenkins @nixCraft I have also been a happy OpenSnitch user, see no reason to recommend something with proprietary crap when there are good alternatives, if it is not full free software that is a huge disadvantage compared with OpenSnitch

@nixCraft Finally!

I miss that see-which-app-opens-which-connection-when and filter it on Linux.
(I remember having a program on Windows 2000 which did exactly that: a personal firewall with a GUI).

@p3ter @nixCraft I bet that app was Zone Alarm? IFLd that and honestly that era might have been peak Windows

I bought a license for a MacBook many years ago, but I no longer use it. Now I only use Ubuntu. I wonder if the license is compatible with Little Snitch for Linux.

or maybe it's free for linux

@x or you can use little snitch to forbid access to its own license-check server. Used to work on macos :)
@nixCraft I have the MacOS version, works a treat!
@siquis
Thanks, I'll try
@x I still use it in a Macbook, I'll have to try the linux version in my Linux Mint laptop.

@siquis
Adobe doesn't like this ... πŸ™‚
(hehehe ...)

@nixCraft

@nixCraft wow, where has this been all my life?? I use nethogs but its not ideal, will give this a try! Thanks!!!
@nixCraft for all the extra features that little snitch has, the only one I care about is the better UX than opensnitch. Opensnitch could close that gap fairly easily really if they just reflect on the usage patterns.
@nixCraft be nice if one can run a gateway / proxy device to the rest of the network
@nixCraft Instead of adding a small comment that most people probably won't see, the original post should include a big warning that this app is not open-source and so there is no way of knowing what it will do on your system.
@ten15bit
@nixCraft
OpenSnitch is open source iirc...
@Albirew Yes, I was referring to the original post, which was about Little Snitch.
@nixCraft it killed my openSuse :(

@nixCraft

And you can get started right there and immediately block #claude and #anthropic !

*plonk*

@nixCraft This runs really well; I just need to get on writing an OpenRC service for it instead of their single systemd provided one.