Not pretty, at least. I'd look towards the TCP fingerprinting techniques that FreeBSD has in its packet filter/firewall. With that, you could make a rudimentar

Not pretty, at least. I'd look towards the TCP fingerprinting techniques that FreeBSD has in its packet filter/firewall. With that, you could make a rudimentary decision how many machines are on the network, regardless if some are bad actors. However, we will still get this problem regardless how much security we do over wifi, as wireless is inherently an insecure protocol. Ideally, we could make decent security with IPSEC, but that would be so cumbersome, as well as in opposition to "Pay us money for easy access to internet." A few non-payers aren't that big of a deal, considering the profit margins I would assume that make.