How do Apple devices using Private WiFi Addresses interact with networks during detection?

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How do Apple devices using Private WiFi Addresses interact with networks during detection?

Any time an Apple device using Private WiFi Addresses connects with a network, it offers something different than the network interface card's (NIC's) hardware MAC address.

When the Apple device only detects a network without connecting to it, does it offer a MAC address that the detected network can log?

If the network can do this, then what is the Apple device offering? Is it the hardware MAC address, or something else created under Private WiFi Address protocols?

My primary concern is that offering the same hardware MAC address to any network you don't connect to could make the Apple device trackable as it moves through a WiFi network ecosystem. This tracking would likely be difficult, perhaps impossible by today's standards, but with artificial intelligence (AI) the capacity for real-time tracking is likely to increase substantially, if not exponentially.

Maximum shielding of hardware MAC addresses would seem to be a desirable goal, and was likely the primary motivation for Private WiFi Addresses in the first place.

[Re-Titled by Moderator]

iPhone X, iOS 16

Posted on Feb 18, 2025 01:24 PM

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Answer 1

Feb 18, 2025 01:32 PM in response to Kirk-RS-9

Kirk-RS-9 wrote:

Any time an Apple device using Private WiFi Addresses connects with a network, it offers something different than the network interface card's (NIC's) hardware MAC address.

When the Apple device only detects a network without connecting to it, does it offer a MAC address that the detected network can log?

Yes, it offers a “fake” Mac address that will not be used for any other Wi-Fi network, and won’t even be used for the same Wi-Fi network if that network is encountered again.

If the network can do this, then what is the Apple device offering? Is it the hardware MAC address, or something else created under Private WiFi Address protocols?

Your Apple device never uses the hardware MAC address unless you turn off Private Wi-Fi address for a specific network (such as your home, school or work network)

My primary concern is that offering the same hardware MAC address to any network you don't connect to could make the Apple device trackable as it moves through a WiFi network ecosystem. This tracking would likely be difficult, perhaps impossible by today's standards, but with artificial intelligence (AI) the capacity for real-time tracking is likely to increase substantially, if not exponentially.

The whole purpose of Private Wi-Fi address is to prevent tracking; that’s why the hardware MAC address is never used unless you turn off Private Wi-Fi address for a specific network.

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Answer 2

Feb 18, 2025 01:54 PM in response to Kirk-RS-9

Kirk-RS-9 wrote:

…My primary concern is that offering the same hardware MAC address to any network you don't connect to could make the Apple device trackable as it moves through a WiFi network ecosystem…

You missed some other cases that the Apple MAC randomization scheme also already deals with, such as network resets, and changing the MAC address over time.

Here are the official details:

Use private Wi-Fi addresses on Apple devices - Apple Support

There are other potential means to track mobile devices however, such as Bluetooth chatter. Continuity chatters, for instance.

There’s also the ever-problematic hidden Wi-Fi SSID, for those that might choose to configure that.

And metadata from (TLS-protected) network connections can also potentially provide tracking fodder.

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Answer 3

Feb 21, 2025 06:18 AM in response to Kirk-RS-9

Kirk-RS-9 wrote:

MrHoffman wrote:

No reasonable Wi-Fi client is going to change MAC in mid-connection.

I agree, sir! Once connected, the MAC address offered must be used until the connection is broken in some fashion.

When I change MAC addresses on my router using the firmware, the connection breaks immediately and must be reestablished once the router reboots.

My concern here is how an Apple device wifi that does NOT connect will behave in terms of broadcasting its MAC address. I can imagine a scenario that it sniffs with its hardware MAC but connects with a generated MAC. I sincerely hope that is not what happens, but I want to verify this with some form of official Apple documentation.

Look for yourself:

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Answer 4

Kirk-RS-9 Author

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Feb 20, 2025 04:06 PM in response to MrHoffman

Thanx MrHoffman for the official Apple info link!

After reading it, I'm still not quite sure what happens when the Apple wifi device does NOT actually connect with a router. I want to believe what Lawrence Finch says, but I still haven't read it in an official Apple document or website. Can you help with that?

I definitely hear what you're saying about other risks (BT, TLS metadata, etc). If you really want to go down the rabbit hole, consider the "Hitchhiker's Guide to Online Privacy", which was being kept up to date until the end of 2022.

I'm content to take steps like anonymising MAC addresses, closing browser leaks like the webRTC (web Real TIme Communications) that report my actual local IP address, changing some IDs on my PC and router/APs, spoofing GPS on demand, and such.

They need to be relatively easy, quick, and reasonably safe to do so I don't brick my equipment!

Anything the big tech entities like Apple can do to support this is always welcome!

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Answer 5

Kirk-RS-9 Author

Level 1

5 points

Feb 20, 2025 09:26 PM in response to Kirk-RS-9

Thanx MrHoffman for the official Apple info link!

After reading it, I'm still not quite sure what happens when the Apple wifi device does NOT actually connect with a router. I want to believe what Lawrence Finch says, but I still haven't read it in an official Apple document or website. Can you help with that?

I definitely hear what you're saying about other risks (BT, TLS metadata, etc). If you really want to go down the rabbit hole, consider the "Hitchhiker's Guide to Online Privacy", which was being kept up to date until the end of 2022. That was before the advent of AI chatbots, the recent discovery that Bluetooth IDs can easily be tracked even when they change frequently, and MIcrosoft's announcement in the past couple of days about their expectations for practical, cost-effective quantum computing CPUs in the next few years. Put AI & quantum computing together with massive data collection of hardware IDs and other markers, and all efforts to preserve online privacy may be doomed.

Setting all that aside for the moment... I'm content to take steps like anonymising MAC addresses, closing browser leaks like the webRTC (web Real TIme Communications) that report my actual local IP address, changing some IDs on my PC and router/APs, spoofing GPS on demand, and such.

They need to be relatively easy, quick, and reasonably safe to do so I don't brick my equipment!

Anything the big tech entities like Apple can do to support this is always welcome!

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Answer 6

Kirk-RS-9 Author

Level 1

5 points

Feb 20, 2025 09:31 PM in response to MrHoffman

MrHoffman wrote:

No reasonable Wi-Fi client is going to change MAC in mid-connection.

I agree, sir! Once connected, the MAC address offered must be used until the connection is broken in some fashion.

When I change MAC addresses on my router using the firmware, the connection breaks immediately and must be reestablished once the router reboots.

My concern here is how an Apple device wifi that does NOT connect will behave in terms of broadcasting its MAC address. I can imagine a scenario that it sniffs with its hardware MAC but connects with a generated MAC. I sincerely hope that is not what happens, but I want to verify this with some form of official Apple documentation.

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Answer 7

Kirk-RS-9 Author

Level 1

5 points

Feb 20, 2025 03:50 PM in response to Lawrence Finch

Thanx Lawrence Finch. This is the answer I was hoping for!

Can you help me find official Apple support online for what you are saying, just so I can be absolutely sure?

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Answer 8

Feb 20, 2025 04:17 PM in response to Kirk-RS-9

No reasonable Wi-Fi client is going to change MAC in mid-connection.

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How do Apple devices using Private WiFi Addresses interact with networks during detection?

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