Is there anything that can without uniquely identify an endpoint? Anything connecting to a network has an IP address and a MAC address burned into its network interface to further identify its individuality, of course, but both of these can be spoofed and are therefore unreliable.

According to a Canadian researcher, however, Wi-Fi devices can be identified from the unique way their internal transceiver chips interact with radio signals, inflecting transmission. Presumably, this would be unspoofable because it relates to the micro-effects of chip manufacture, and that differs to a tiny degree from chip to chip.