This is one of the reason you need to segregate your whole LAN. At the bare minimum, use VLANs to knock off these ruthless scanners. And obviously, this wouldn't be possible if you used a strong adblock list on whatever DNS you're running. They cannot touch the people who take proper measures. I also do not believe people who use Facebook really care about privacy. I am well aware of how mean this sounds but they fully deserve to be tracked