The page you have linked to won't even open. I have witnessed a number of attempts to replicate LittleSnitch on Linux, none of them went far enough to anything near a usable product quality.
You need to implement at least some functionality on the kernel level (what LitleSnitch does with a kernel extension) for this, most of the people who care about desktop apps on Linux (me included) lack kernel developer skills.
You need to implement at least some functionality on the kernel level (what LitleSnitch does with a kernel extension) for this, most of the people who care about desktop apps on Linux (me included) lack kernel developer skills.