Ethernet and wifi MAC addresses are not permanent. On linux machines you've been able to change ethernet mac addresses for something like two decades. MacOS X

Ethernet and wifi MAC addresses are not permanent. On linux machines you've been able to change ethernet mac addresses for something like two decades. MacOS X has easily accessed MAC address configuration, also been possible for many many years. Ditto for wifi cards. iOS 14 and above uses a randomized wifi mac address on a network unless you specifically turn it off. iOS 8 or 9 introduced MAC address randomization for broadcast stuff like network probes. Android 10 does the same (it was available in 9 under dev options.) For Bluetooth, it sounds like BTLE allows for some forms of mac address randomization that was intended to improve privacy, but it's been defeated: https://9to5mac.com/2019/07/18/bluetooth-flaw/ https://9to5mac.com/2019/07/18/bluetooth-flaw/ Bluetooth smart watches, headphones, car audio, sports sensors (heartrate, running gait sensors) have made it completely trivial to track someone's whereabouts. Assume that almost any major retailer has long since associated MAC addresses with a customer profile on you. There's a reason Amazon makes it impossible to use Prime at Whole Foods without your cell phone running the app or having the website up with a live connection; the QR codes are valid for barely a few minutes.