Thanks to the efforts of the OpenSnitch lead developer Gustavo Iñiguez Goya allowing me to sponsor the upload, the interactive application firewall OpenSnitch is now available in Debian Testing, soon to become the next stable release of Debian.
This is a package which set up a network firewall on one or more machines, which is controlled by a graphical user interface that will ask the user if a program should be allowed to connect to the local network or the Internet. If some background daemon is trying to dial home, it can be blocked from doing so with a simple mouse click, or by default simply by not doing anything when the GUI question dialog pop up. A list of all programs discovered using the network is provided in the GUI, giving the user an overview of how the machine(s) programs use the network.
OpenSnitch was uploaded for NEW processing about a month ago, and I had little hope of it getting accepted and shaping up in time for the package freeze, but the Debian ftpmasters proved to be amazingly quick at checking out the package and it was accepted into the archive about week after the first upload. It is now team maintained under the Go language team umbrella. A few fixes to the default setup is only in Sid, and should migrate to Testing/Bookworm in a week.
During testing I ran into an issue with Minecraft server broadcasts disappearing, which was quickly resolved by the developer with a patch and a proposed configuration change. I've been told this was caused by the Debian packages default use if /proc/ information to track down kernel status, instead of the newer eBPF module that can be used. The reason is simply that upstream and I have failed to find a way to build the eBPF modules for OpenSnitch without a complete configured Linux kernel source tree, which as far as we can tell is unavailable as a build dependency in Debian. We tried unsuccessfully so far to use the kernel-headers package. It would be great if someone could provide some clues how to build eBPF modules on build daemons in Debian, possibly without the full kernel source.
As usual, if you use Bitcoin and want to show your support of my activities, please send Bitcoin donations to my address 15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.