Friday, October 30, 2020

MAC Address Randomization in iOS 14

Jon Baumann:

What caused my issue was the fact that Apple was now defaulting to using “private Wi-Fi addresses” in iOS 14. This did not appear anywhere in the list of “All New Features” on the iOS 14 website, but there was some buzz about it for those that follow iOS news. As I am woefully behind on iOS news, I learned about it when I hit Settings->Wi-Fi->[My SSID], saw that “Private Address” was checked to “Yes”, and noted that the different MAC address my router was complaining about was being displayed on my phone. Once I turned that setting off, my expected MAC address was back and I got network access again.

To be clear about the term “Private Address”, this is Apple’s term for MAC address randomization. MAC address randomization is just a systematic way of doing what many of us have done for decades: talking to your network using a different MAC address than what is actually burned onto your network card. In this case, Apple gave out a link-local MAC address which is not guaranteed to be globally unique, in an OUI which was not reserved for Apple. With “private addresses”, Apple provides a different MAC address for each network you connect to in hopes of protecting your privacy. I say “in hopes of” because I generally find it comical for a company to implement a “turn off Wi-Fi button” which helpfully says “turning off Wi-Fi until tomorrow“ and then force “private addresses” by default. Or for the same company in the same iOS release to openly say they’ll bounce the pictures you have tagged on your phone against your security cameras and tell you who they think is at the door. Or for the same company to accidentally tell you all networking is turned off when it clearly isn’t.


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