Little Snitch, the macOS network tool, is now available on Linux (omgubuntu.co.uk)

built something similar for Linux/Mac and from the mobile too https://saltserv.com/posts/cura-sysadmin-server-monitoring-a...

Little Snitch is what I'd call Fantastic Software. That being said I had to uninstall it because I was getting way too fiddly with it.