iPhones have been exposing your unique MAC despite Apple’s promises otherwise — “From the get-go, this feature was useless,” researcher says of feature put into iOS 14

You are who you say you are to a network though, at least at layer 2.

If you say you’re one MAC address one time and another next time then so you are.

Let me give you an example. Let’s say I’m a device trying to connect to a network. Among other things I tell it “can I have an IP address, my MAC address is Majestic”. It says in turn, sure and notes down Majestic and routes or switches things to me when another device says it wants to reach my IP. In Wi-Fi it basically shouts out it has a packet for Majestic and sends it out onto the air with my unique encryption key I previously negotiated and I am listening for packets for Majestic and grab and process that packet. Now if I go back and connect again and call myself Dull it’ll do the same thing. Those names being stand-ins for MAC addresses of course.

This is simplified of course. And this is why MAC whitelisting is a futile attempt at security.