What is the meaning of 'application' in unix environment? Particular process? Process created from particular file? From set of files? What is the point of such "firewall" if applications are not in sandbox?
It's interesting, why all this 'mobile' articles of happy networkmanager users are full of such frustrating concepts, not well thought, not UNIX-way.
Linux is based on very well established standards, like POSIX or system V. Now then something should be added, everything goes thought childish approach "we need x let's add y" without investigation is the y really best solution to solve x. That's why replacing sysvinit with systemd is a problem, and this article look like praising attempt to replace network with something out of windows-oriented minds, overcomplicated, not well thought, and based on weak concepts of "per-application firewall". Makes me worry about Linux future.