Ask HN: How does a Mac determine your location during set-up? | Hacker News Reader

Ask HN: How does a Mac determine your location during set-up?

3 pointskeraf7 comments

A friend just brought me a Macbook Air (2019) to Greece where I am currently located. The computer came from another European country and was reset to factory settings before the trip. When I started the setup, Greece was pre-selected on the country/region picker before even connecting the computer to a network. How is this possible?

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Because the nearby Wi-Fi stations transmit on which country they’re configured also if you are not connected to them. Try to boot it in the middle of a countryside with your phone the Wi-Fi and Bluetooth disabled and it should display the default country (I think is USA?! I don’t remember).

This is also the same cause why Apple is using Wi-Fi and Bluetooth with the GPS to retrieve your precise location. And this is also you should turn OFF (not tap on the icon from the control center) the Wi-Fi and Bluetooth: your privacy.

> Because the nearby Wi-Fi stations transmit on which country they’re configured

That's news to me. Where is that information encoded? As far as I know all you can get is the SSID and Mac address. I am intrigued.

The router sends continuously messages in order to advise/tell to the clients “Ehy, I’m the XYZ Wi-Fi SSID, would you join me?” And in these messages -packets- are stored these informations.

Read this: https://en.wikipedia.org/wiki/Wi-Fi_positioning_system

Yes that is how mobile phones do without GPS, but wouldn't that mean they would need the entire Mac address database for the world if they had no internet connection?

The country code is included in the packet.

The beacon frame optionally includes country information, see this reference under country:

https://mrncciew.com/2014/10/08/802-11-mgmt-beacon-frame/

If enough nearby access points include consistent information, seems like a reasonable place to start.

Your IP address or other networking introspection most likely

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