Hacker News Reader

Comment by stock_toaster | Hacker News Reader

ios devices (unsure about android) use random MACs on wireless networks by default.

https://support.apple.com/en-us/102509

The random MAC is generated only once per network, and re-used for every subsequent future connection to it, until the network settings are reset

The random MAC would still be within the vendor prefix though, and a MAC address won’t identity a specific device type anyway.

Edit: I’m wrong

No it isn’t, vendor prefixes are sort of an anachronism. Bit 41 - bit 1 of the first octet is reserved for local (random) use. That and the group bit (40) set to 0 means the second digit of the human readable MAC is 2, 6, A or E, but that’s it.

My bad, thanks for the correction! You still can’t identify a specific device type based on the MAC address though, right?

On the same WiFi network yes you can - it uses the same MAC on the same SSID. Remembers the "random" MAC after the first connection (and if you first connected to the networks before they added MAC randomisation in iOS14, it "remembers" the actual MAC of the device, so you didn't have compatability issues after the iOS14 upgrade).

So you can't use it to track devices between multiple SSIDs including when scanning for networks, but you can use it to persistently identify a device when connected to the same network.

You misread the question.

Yep, you're right. Agree with the other post - the randomly generated MACs have no manufacturer info.

Other than perhaps the manufacturer from the OUI, no.

There’s no manufacturer in a randomly generated local OUI.

Random aside for this, I believe this functionality existed for many years but actually hasn’t worked until recently. (Take this with a grain of salt)

I had to turn random MAC off, my google mesh could not handle it. Wifi on my samsung phone would only work for a couple of minutes.

Reply on news.ycombinator.com