4 ms·
Thought about this too a while back. If I remember correctly the "issue" (actually I consider it a feature) with most modern smartphones is that they will rando
by jcfrei 8y ago
Thought about this too a while back. If I remember correctly the "issue" (actually I consider it a feature) with most modern smartphones is that they will randomly change their MAC address in order to prevent exactly this kind of tracking.
- crankylinuxuser 8y agoHowever, if your wifi is on and not connected to an AP, then you will broadcast mgmt frame pings with the correct MAC for all the networks you've been connected to. An enterprising hacker could submit those to wigle and figure out not only uniques, but also tell what geographical part of the world you're from. Nicer hackers share this for public knowledge on HN :-D (edit: really? -1'ed? How is this wrong? Would love to hear from detractors, as this technique is how malls and supermarkets track individual users.)
- walterbell 8y agoiOS has sadly made it more difficult to disable WiFi in Control Center (turns back on after fixed time). I wonder if iOS12 Shortcuts could perform geofencing of WiFi.
- rsync 8y ago"edit: really? -1'ed? How is this wrong?" No idea. I downvoted you because you complained about your downvotes. Don't interrupt the discussion to meta-discuss the scoring system.
- crankylinuxuser 8y agoYou mean, doing what your response is doing. How interesting.
- gkfasdfasdf 8y agoDo you have any idea how often they change? Like if you were only looking counts of distinct MAC addresses, could you shorten the listening window so that an individual phone would have the same address?
- eli 8y agoNot often at all
- copperx 8y agoIt would be interesting to have an exact number of how probable is to have a MAC collision in the wild.
- bigiain 8y agoIt's 48bits, so a space or around 2.8 million billion possibilities, so you'd need a over a million billion devices to have a 50% chance of collision. _If_ everything was statistically randomly distributed across the entire address space. But they aren't. There's a few kinds of structure in MAC address formats that reduce that but potentially a _lot_... Theoretical worst care, a MAC address has 24bit of organisation identifier and 24 bits of device identifier. So If an organisation/manufacturer only makes one model of device, they'd "only" need to build ~16.7 million (24bits) of them before they repeated a device identifier (if they chose not to use up any of their organisation bits to reflect that rollover). Again, maybe half that if they just randomly choose a device ID each time instead of enumerate the space. Practically? Manufacturers screw up... https://www.raspberrypi.org/forums/viewtopic.php?p=902294 https://www.raspberrypi.org/forums/viewtopic.php?p=902294 Oooops... (Also, many Wi-Fi adaptors have easily changeable MAC addresses. Back in the day when cafes used to charge for Wi-Fi access, it wasn't uncommon to sniff the network for a "paid up" MAC address, and either wait til they left and use it, or de-auth them and do a hostile takeover of their paid-for internet access. Apologies to anyone who used to pay for "unreliable" Wi-Fi at Atlas Cafe on Alabama St back in the late 90s/early 2000s...)
- diminoten 8y agoMost modern smartphones will break open WiFi networks that offer for-pay plans or require a registration step? That sounds intuitively and anecdotally incorrect.
- hk__2 8y agoOne MAC address per network doesn’t break anything.
- diminoten 8y agoBut it's also not how phones work, so it's not accurate.
- tastroder 8y agoNot really, they simply only randomise for scanning / management frames when not connected to an AP. The downside is that many people have rather unique sets of SSIDs that still allow for pretty good tracking markers.
- wstuartcl 8y agoThey do retain the mac for scanning networks that they have previously connected to AFAIK. This is what allows the correlation of mac approved (ie paid or bound mac networks).