alt.hn

2/16/2026 at 2:39:32 PM

What your Bluetooth devices reveal

 https://blog.dmcc.io/journal/2026-bluetooth-privacy-bluehood/

by ssgodderidge

2/16/2026 at 3:52:14 PM

> We’ve normalised the idea that Bluetooth is always on. Phones, laptops, smartwatches, headphones, cars, and even medical devices constantly broadcast their presence. The standard response to privacy concerns is usually “nothing to hide, nothing to fear.”

I guess anything you send out can be used to profile you.

Some of my friends live on a farm near a semi busy road, however far enough from other farms to not be able to receive their wifi. They showed me their router logging all the wifi accesspoints that appear/disappear. There where A LOT of access points named "Audi", "BMW", "Tesla" etc. similar to those devices leaking bluetooth data. We had a discussion that it would be easy to determine who was passing by at what times due to these especially when you can "de-anonymize" the data for example link it to a numberplate.

I believe shopping malls often use such signals (wifi, bluetooth) to track what your travel pattern through the mall is. They know what section of the store you spend most of your time in and what storefronts you stall at.

by trashb

2/16/2026 at 8:57:21 PM

You can do this for much cheaper - all four of your tires are broadcasting a unique ID to report tire pressure, the radio to pick it up is cheap (because cars), and TPMS has no facility to randomize or otherwise secure this.

by luma

2/16/2026 at 9:12:13 PM

It’s actually even easier, your car has a plate on the front with a unique ID that a camera scans, often to automatically track your park time for ticketing.

I can’t really care about obscure Bluetooth tracking when every business has CCTV doing facial recognition.

by Gigachad

2/17/2026 at 12:34:52 AM

Also, you can read the plate from much farther away than the TPMS sensors.

by userbinator

2/17/2026 at 2:11:03 AM

Wait they use this for parking meters?! Which cities?

by hammock

2/17/2026 at 2:24:11 AM

I think they’re pretty common.

Only reason I know is because I wondered if I could walk to the booth and press the button for a new parking ticket and pay for 5 minutes instead of 4 hours..

by harrall

2/16/2026 at 11:09:11 PM

Yeah exactly, with a car I would no longer be expecting any type of privacy, sadly.

Here in Holland we must even have a mobile phone module in every car so it can call the emergencies in case of a crash.

by wolvoleo

2/17/2026 at 1:57:37 AM

It’s all of the EU. It’s literally illegal to sell new cars without a radio transceiver in them.

by sneak

2/17/2026 at 3:06:29 AM

But is it illegal to personally disable it?

by userbinator

2/16/2026 at 9:08:50 PM

Not all cars have active TPMS. my Volvo xc90 had them but in later models they switched back to passive ones. So it is not even a given for higher end models.

by spockz

2/16/2026 at 10:15:11 PM

That's not quite the end of the road, though: The tires themselves often have RFID tags embedded.

https://rfid.michelin.com/what-is-rfid/

by ssl-3

2/17/2026 at 12:26:04 AM

much harder to read rfid at a distance

by m-s-y

2/17/2026 at 1:26:20 AM

It is.

My read through this document suggests that the maximum usable range may be as far as 5 meters, or as little as 1 meter: https://rfid.michelin.com/wp-content/uploads/2024/07/dataShe...

That's not as far as BLE or TPMS can work at, but it's not exactly like the NFC arrangement in a credit card, either. 5 meters is enough for a motivated attacker to do some undetected bulk data collection.

by ssl-3

2/16/2026 at 10:29:23 PM

I've had trouble reading these from more than a few feet away, but I concede that I have no idea what I'm doing

by stirfish

2/16/2026 at 4:38:36 PM

>There where A LOT of access points named "Audi", "BMW", "Tesla" etc.

That's one of the funniest things about wardriving with Wigle on your phone. I can often see the SSID of "Jennifer's Equinox", "Jacks Suburban" right after I get cut off by someone in said vehicle. The vast majority of car bluetooth/wifi I see tends to have varying amounts of identifying information. It's almost as bad as the fact that apple still defaults to Jacks iPhone/iPad etc with no option to rename the device until you've finished setting it up.

Companies are not out to protect us with default settings and the majority of users need to wake up to this fact.

by officeplant

2/16/2026 at 5:43:46 PM

This might just be me being uninformed as someone who doesn't drive but how are you seeing what wifi networks are available so quickly right after being cut off? My very naive instinct is that looking at your phone or opening up a menu with the available wifi networks on your car's display seems like it would require a noticeable decrease in attention to the road, so I'd almost expect an uptick in being cut off from other people who are annoyed with your driving.

by saghm

2/16/2026 at 6:26:20 PM

Small town, phone is on a dash mounted holder. Sometimes I leave Wigle up just to eye every now and then to see how much crap I'm picking up while war driving.

I am not without sin when it comes to driving a car.

by officeplant

2/16/2026 at 7:07:29 PM

What would be next level wardriving would be to break into their Bluetooth and have a conversation about their driving habits.

It can be done, relatively easily.

by reactordev

2/17/2026 at 2:55:46 AM

> I believe shopping malls often use such signals (wifi, bluetooth) to track what your travel pattern through the mall is.

I worked for a company about 18 years ago where we did just this. We also sold the technology to car dealerships who were very interested in our silent salesman stuff where you could tie interactions with your web campaign directly to the person walking past the dealership and preload the salesman with all their details.

Grubby stuff nearly two decades ago.

by King-Aaron

2/16/2026 at 8:42:48 PM

> I believe shopping malls often use such signals (wifi, bluetooth) to track what your travel pattern through the mall is. They know what section of the store you spend most of your time in and what storefronts you stall at

In the EU this is forbidden unless they explicitly ask your permission. They can still gather aggregate stats but they cannot build a profile on you.

by jorvi

2/16/2026 at 11:27:02 PM

True but I wouldn't put it past them tbh. It's very easy to hide or claim a 'misconfiguration'.

Even the airports here track everyone. They say it's for public safety but I'm sure they use it for market analysis for their expensive sandwich shops too.

by wolvoleo

2/16/2026 at 5:41:02 PM

Don't worry about Tesla's being tracked. Via Bluetooth this has existed for at least 7 years [1] (was mentioned on HN as well). Tesla know (also for 7 years), Musk doesn't care 'since license plates can also be tracked'.

I used it in train stations, and get hits when passing highways via train or bus. Esp. fun if you stand still due to traffic lights or traffic jam, since you can try to get a visual.

The only lesson to be learned here is that it allowed one to learn in 2019 Musk is overrated. But you can also learn that lesson from the book The PayPal Wars which predates this by 15 years.

> I believe shopping malls often use such signals (wifi, bluetooth) to track what your travel pattern through the mall is. They know what section of the store you spend most of your time in and what storefronts you stall at.

Not allowed in EU.

[1] https://www.teslaradar.com/

by Fnoord

2/16/2026 at 8:45:08 PM

> Not allowed in EU.

I'm surprised, I know for a fact that some stores definitely have the ability to do that on their hardware.

by xaldir

2/17/2026 at 1:17:37 AM

Utrecht Central Station does this, there are stickers at the entrance notifying the ‘public’ of this. Or its just a sticker;p

by thenthenthen

2/17/2026 at 12:28:17 AM

and i can commit crimes with my kitchen knives, yet they’re still legal

by m-s-y

2/16/2026 at 4:57:26 PM

There's an Android app that can find devices, make profiles, and you can track location for as long as they're connected. So you can profile passerbys and even get notified when the profile passes through again. I forgot what is was called

by jasonfrost

2/16/2026 at 7:20:54 PM

Years ago when BT beacons were newish, I was talking to an AdTechBro that wanted to create the ability from Minority Report where the kiosk recognizes a user, not by eye scans but by recognizing mobile device, so they could offer a personalized whatever. The creepiness wasn't something they eased into. It was pretty much instant.

by dylan604

2/16/2026 at 11:11:56 PM

> I believe shopping malls often use such signals (wifi, bluetooth) to track what your travel pattern through the mall is. They know what section of the store you spend most of your time in and what storefronts you stall

They do but most phones rotate the mac adress these days. So while they can still track you through the store (sadly) they don't have the ability to track your recurring visits.

I wish phones had the option to constantly spam broadcasts with random MAC ids. That would make the practice useless.

by wolvoleo

2/16/2026 at 5:55:29 PM

> I believe shopping malls often use such signals (wifi, bluetooth) to track what your travel pattern through the mall is. They know what section of the store you spend most of your time in and what storefronts you stall at.

Yes, I remember Cisco had a product like this all the way back in 2011. They could pinpoint a customer to an exact position inside a store using triangulation, they would know which shelf you spent time in front of etc. In the 15 years since then, I expect the technology is much scarier and intrusive.

by tskulbru

2/16/2026 at 8:11:22 PM

iBeacon. They know what shelf you're standing in front of. What products you touch and read.

Ever been in an Apple store? Look up. In the dark voids between the edge-to-edge backlit ceiling. There are secrets there. Watching you.

by nofunsir

2/17/2026 at 1:01:55 AM

Not what iBeacon does but an entertainingly dramatic description nonetheless.

by astafrig

2/16/2026 at 8:52:33 PM

Macys pioneered it before there even were Apple Stores. Back when most people didn't even know their phones had Bluetooth.

by reaperducer

2/16/2026 at 9:48:36 PM

Macy's has Santa clause since 1947 because that is when Miracle on 24th Street came out. And he even knows when you are sleeping.

by shafoshaf

2/16/2026 at 7:36:39 PM

> We had a discussion that it would be easy to determine who was passing by at what times due to these especially when you can "de-anonymize" the data for example link it to a numberplate.

You could also read the numberplate directly with OpenALPR. It can be finicky to set up a camera to do this reliably in all conditions (particularly at night and high speed) but once done you could detect any car passing, not just ones with wifi access points.

When the law requires us to have numberplates, I think this just has to be considered public information for anyone who is nearby or can leave a camera nearby. It's not ideal to leak it in additional forms that might be easier for people to grab (say, with an ESP32), but it's a matter of degree rather than of kind.

But yeah, I'm with you on some of these others, particularly the medical devices. That's not great.

by scottlamb

2/16/2026 at 8:36:06 PM

There's a difference between public and Public. I go outside with my face visible and I don't mind if my neighbors see me. I do mind if my neighbors stand outside my door with a notepad sketching faces every time they see me or anyone else, especially if they're selling the data. Systematic tracking that isn't subject to the constraints of human memory and apathy fundamentally changes the equation.

by AlotOfReading

2/16/2026 at 10:08:33 PM

> Systematic tracking that isn't subject to the constraints of human memory and apathy fundamentally changes the equation.

I definitely don't approve of mass collection across many cameras, accessible to who-knows-who with minimal if any privacy controls (Flock). But it wouldn't surprise or bother me if my next-door neighbor had ALPR enabled, as long as it's not part of that cloud. YMMV.

Full disclosure: I develop an open source home/hobbyist-oriented NVR, although it doesn't have an ALPR feature or any other analytics today.

by scottlamb

2/16/2026 at 9:05:37 PM

> constraints of human memory and apathy

i like that a lot, brother, thank you!

by thedrexster

2/16/2026 at 4:40:23 PM

I disable bluetooth on my phone, though periodically I find that it's back on.

Edit: iOS

by SoftTalker

2/16/2026 at 5:02:08 PM

I have the opposite experience: GrapheneOS has an option to automatically turn your bluetooth off after a configurable period of not being used. So when I need to use bluetooth, I turn it on like normal. Then, without thinking about it, it automatically turns off. The end result is my bluetooth is only ever on for a couple hours each month when I'm making phone calls.

by craftkiller

2/17/2026 at 2:36:36 AM

Your problem is that you chose an OS that respects you and treats you with dignity.

by 9991

2/16/2026 at 8:00:47 PM

I only see an option to turn back on tomorrow. How do you find this option?

by rationalist

2/16/2026 at 11:09:13 PM

It's under Settings > Security and Privacy > Exploit Protection > Turn off bluetooth automatically

Definitely not the most obvious location. I would have expected to find this under the bluetooth settings.

by craftkiller

2/17/2026 at 3:50:31 AM

Awesome, thank you.

I don't recall that being there when I first installed GrapheneOS. I need to go through the settings more often I guess.

It might be a cool feature if settings were highlighted or had a red dot or something until it was viewed (like an unread notification).

by rationalist

2/16/2026 at 6:58:24 PM

Did not realize I could do that! Thank you!

by littlecorner

2/16/2026 at 11:12:32 PM

I used to fervently keep my bluetooth off on iOS, and I learned that if you turn it off via the Control Center, then it automatically gets turned back on the next day. But if you turn it off via Settings, then it only gets turned back on when the system software updates. (I stopped doing this a couple iOS versions ago, though, so it may have changed since then.)

by joemi

2/17/2026 at 12:12:33 AM

Bluetooth (and wifi) aren't turned off at all through the Control Center - they changed the wording to say "disconnected", meaning that your phone only disconnects from known devices. But both are still turned on for other purposes such as CarPlay, Handoff, and Location Services (via wifi). For the purposes of this discussion, they are potentially still transmitting a known identifier.

Apple reconnects to known devices and networks at 5am:

https://support.apple.com/en-us/102412

Bluetooth and Wi-Fi Aren't Fully Disabled When Off in iOS 11 Control Center

https://news.ycombinator.com/item?id=15297387 (2017, 143 comments)

by jerlam

2/16/2026 at 7:22:16 PM

I miss wired headphones for this purpose. It's the only reason I even have BT enabled.

by dylan604

2/16/2026 at 6:38:36 PM

With iOS the easiest way to make sure it off and stays off is to build a shortcut to cut off wifi/bluetooth. Otherwise it's typically off until you get geolocated as being back home/work and wifi comes back on.

I have a "store mode" button that just kills wifi/bt that I hit before I go into any store.

by officeplant

2/16/2026 at 8:49:56 PM

what do you gain doing this?

by mcosta

2/16/2026 at 9:15:26 PM

Peace of mind that I'm not being tracked around the store by wifi/bt, and/or having my device fingerprinted for further identification on future visits.

by officeplant

2/16/2026 at 5:40:44 PM

Android now has an option to enable it every day.. (I have it disabled).

by silon42

2/16/2026 at 11:14:39 PM

Sure, stores use WiFi access points and BT to track MAC addresses and BT device IDs. Google does something similar with location and it provides in real time how busy a location is which I find super convenient. It’s a shame that shaping data into useful information also means it can weaponized.

by voidmain0001

2/16/2026 at 7:46:23 PM

The GrapheneOS variant of Android will disable both Bluetooth and WiFi after a set period of inactivity.

There is also a Bluetooth shutoff app on F-Droid.

https://f-droid.org/en/packages/com.mystro256.autooffbluetoo...

I have also put an Airtag clone in my car (Loshall in iOS mode). That is probably leaking my arrival times. My water meter is also now bluetooth.

by chasil

2/16/2026 at 5:26:47 PM

> I believe shopping malls often use such signals (wifi, bluetooth) to track what your travel pattern through the mall is.

Many places do this. The department stores in the mall, target, even grocery stores do it.

by autoexec

2/16/2026 at 4:11:45 PM

> even medical devices constantly broadcast their presence

I mean yes, said medical devices are a whole lot less useful to me if they are not transmitting data. For some of this stuff you can't have your cake and eat it too.

by pixl97

2/16/2026 at 4:40:13 PM

I was wardriving my neighborhood and realized my elderly neighbor's CPAP machine is broadcasting some type of BT signal 24/7. I imagine it's transmitting some important stats, but it did make me have a 2nd thought about medical devices being IoT or BT enabled.

by 0x1ch

2/16/2026 at 11:28:53 PM

Yeah I always keep my cpap on airplane mode. It even had 5G. The therapist complains they can't monitor it but I have to come in with the machine and SD card every few months so they can check it then. They don't need 24/7 access.

What bothers me more is that my sex toys broadcast on Bluetooth even when I'm using them through WiFi. It even says the brand in the device name.

Not that I give a fuck what the neighbours think but it's just none of their business. And some toys are for discreet outdoor use too. Though that's not my thing.

In the past I renamed one of my phones to "Lovense Hush" to troll, though I've never seen anyone looking suspiciously. I guess most people aren't creeps like me who check stuff like that :)

by wolvoleo

2/16/2026 at 6:12:31 PM

> being IoT or BT enabled

Please don’t conflate these two. I have lots of BLE wearables and other sensors. They only send data to my own computer which I control, unlike IoT devices which by definition send to a third party on the Internet. To me it is far more important to protect against strangers on the Internet versus someone wardriving the neighborhood.

On a related note, did you know that EU has a Radio Equipment Directive (RED 2014/53/EU) that came into effect in 2025. It all but guarantees that such Bluetooth communication will be encrypted.

by kccqzy

2/16/2026 at 10:18:43 PM

> I have lots of BLE wearables and other sensors. They only send data to my own computer which I control

That's perhaps technically correct, but a naive interpretation of the risk. I don't need to see the data your BLE devices are sending you, all I need is traffic analysis and meta data from the signals they are broadcasting - and they broadcast that to anyone within detection range which includes attackers with much higher gain antennas than you who can likely pick up those broadcasts at ten times the distance any of your devices will communicate at.

"Flying helicopters low and slow over the Tucson desert in Arizona, the FBI has been using "signal sniffers" to try to locate Nancy Guthrie's pacemaker.

As the search for the 84-year-old mother of US Today show anchor Savannah Guthrie entered its third week, investigators took to the sky with advanced bluetooth technology.

They were hoping to pick up signals emitted from the device implanted in Ms Guthrie's chest to help trace her whereabouts, US media outlets NewsNation and Fox News reported."

https://www.abc.net.au/news/2026-02-16/nancy-guthrie-pacemak...

by bigiain

2/16/2026 at 4:32:26 PM

There’s a middle ground here. There is no technical reason a pacemaker constantly broadcasts itself - there is ways to allow communication to such devices without yelling your name all the time. And there is definitely no reason for such a name to be a unique identifier.

by xanrah

2/17/2026 at 2:50:44 AM

That middle ground has been eroded by cost-cutting.

Example: my mother had a cardic resynchronization device, and it had some kind of NFC type thing to enable the full wireless comms mode: wave a wand over her shoulder and the device's radio wakes up for a set time to send data or receive adjustments. So it wasn't always transmitting, but it did require the doctor's office or hospital to have that NFC wand to initiate any kind of data aquisition or reconfiguration. If it has an always-on BLE radio, the provider would just needs the phone/tablet/laptop with appropriate software that is already required.

Since any device like is already going to have a radio equivalent to a BLE radio, then removing the NFC parts from the device (and especially from the provider side) is some amount of cost savings. I think most patients would disagree that this privacy trade-off is NOT worth it, but you have remember that the patients aren't usually the actual customers in the US health care system. (And most manufacturers are going to have the US market as a target at least somewhat.) The most common actual customer is actually the insurance companies, and they'll take every single fraction of a penny, along with "an arm and a leg".

by just6979

2/16/2026 at 10:55:15 PM

There are technical reasons, though.

Let's suppose we have a pacemaker, and it has data that is beneficial to read -- maybe even in real-time on their pocket computer, or opportunistically as the patient walks by their reader-device, or however that is done.

So we want this data, and we want it over RF. It probably seems obvious that it should only transmit when it is told to do so, right?

So how do we tell the pacemaker to transmit? On its face, that problem seems solved by integrating a receiver that sits and waits for a valid instruction.

Except: That receiver takes power to run. And since changing batteries inside of a person is problematic, we want them to last as long as they can while still performing the desired task.

Now we get to the not-obvious part: In terms of power, it's often less costly to intermittently transmit a string of data than to continuously operate a radio receiver. And maybe it's a bad idea to have an implanted pacemaker that has an open receiver for anything nearby to try to fuck with, anyway.

But a transmit-only radio? Good luck hacking that.

So... we do intermittent transmission, and this works for pacemakers. It also works for the cheap Zigbee thermometer I have (wherein I don't normally request the temperature; it just delivers it periodically, and it runs for years and years on a coin cell).

(Now: Should that pacemaker data be encrypted? Yes, of course. And so should the ID. In fact, the whole transmission should be indistinguishable from background noise by unrelated devices. In this way, authorized devices can then use pre-shared keys to receive and decode these messages and others receive nothing. That kind of cuts BLE and thus also the pocket computer out of the monitoring mix, but tradeoffs are tradeoffs.)

by ssl-3

2/16/2026 at 5:24:21 PM

I mean if not a name, how would a mac id be any different?

by pixl97

2/16/2026 at 5:29:41 PM

What forces devices to constantly stream data? You can batch updates and probably save power thanks to it.

by dietr1ch

2/16/2026 at 6:22:39 PM

Because these BLE devices are so cheap that they don’t have storage. And BLE transmission is already very power efficient: the power consumption of BLE is probably the same order of magnitude as powering flash storage.

by kccqzy

2/17/2026 at 3:38:56 AM

Heard a talk in Paris about a guy who "war drove" around town using a higher layer Mobile IP ap which could sweep up open SSID, connect, and (ab)use the bandwidth to maintain a link "above" it (I guess like an agile VPN)

he was getting 100mbit class speeds routinely. Also patches of nothing, but it was interesting. That was over 5 years ago.

by ggm

2/17/2026 at 1:52:36 AM

I am personally aware that Washington DC, same areas of Maryland, Virginia and Delaware have been tracking car Bluetooth (and EZ-Pass) for decades for "traffic management". The more BT detected the heavier tracking. The longer time between detectors for the unique BT/EZ-Pass, the slower the traffic. Adjust traffic lights down the road to improve traffic flow. (when I write Ez-Pass, i mean the toll transponder, but not detected by a toll booths or overhead arches.)

by WaitWaitWha

2/16/2026 at 3:15:27 PM

Tangential, sort of: in the early days of mobile phones for the masses, when there was no WiFi/3G in the underground, I will often enable Bluetooth in my phone, look for nearby devices and try to match names and looks.

That was before everyone had their "John's IPhone" or "Samsung A55" boring names everywhere and some of us cared to personalise our device's name.

Anyone else played this game?

by TheSilva

2/16/2026 at 6:09:47 PM

hmmmmm...

2006, sat in a job interview. Interviewer says he'll Bluetooth over a file to me - what's by phone's name?

2006, the year that Tool's 10,000 Days had been released, which I was enjoying and, being a bit of an Edge Lord, I'd named my device after a lyric from Vicarious - which, IIRC fit perfectly into the name space and made me very happy:

> ILikeToWatchThingsDie

Excellent. Still got the job though!

by herghost

2/16/2026 at 5:19:53 PM

Hah, I change my device name and wifi hotspot all the time...

"[Agency-acronym] Surveillance Van #43/44/etc.."

by jjkaczor

2/16/2026 at 11:40:10 PM

What I remember is that you could push OBEX calendar objects without much refusal from the phones and make people have alarms ringing at 3am, fun times!

by fer

2/16/2026 at 4:14:57 PM

Yeah, but it stopped pretty soon stores figured out that they could flood you with advertisements over Bluetooth. In some places it was bad enough that I had to turn off Bluetooth.

by oarla

2/16/2026 at 5:13:41 PM

How did this play out? Were the ads from an app from the store that you had installed? Or did they spam you over SMS because they associated your bluetooth info with an account you have with the store, or contact info they bought from a third party?

by patja

2/17/2026 at 1:30:14 AM

As someone explained it below in this thread, walk into a mall with Bluetooth turned on and phone starts chiming with multiple "... wants to send you a media/audio/image etc." Not just ads, some bad actors would try to infect the phone with malware. Luckily never happened to me, but I heard from my acquaintances.

by oarla

2/16/2026 at 7:28:55 PM

> Were the ads from an app from the store that you had installed?

This is my main concern over installing apps in general but specifically store apps. I've noticed that grocery stores are moving past existing loyalty cards and want you to use their apps for exclusively available digital coupons. The prices I'm seeing are very compelling and are on top of existing loyalty card discounts, and I could see lots of people using the app because of it. The assumed amount of abuse keeps me from lemminging my way through the store.

by dylan604

2/16/2026 at 11:04:29 PM

Neither. They used to discover your device and then send a Bluetooth push. "Would you like to receive a file from …"

It was usually an image, movie, or audio file.

by edent

2/17/2026 at 12:31:12 AM

Wow that is wild. Thanks for explaining.

I've never seen a prompt like that on my phone and would not have guessed this.

by patja

2/16/2026 at 3:20:33 PM

Yep 100% did the same.

It was interesting to see what people named stuff as even back then I figured you could use that metadata for tracking devices...but even more interesting was looking at the Mac address to see the manufacturer and try and find some rare or cool device.

by tonetegeatinst

2/16/2026 at 3:20:53 PM

I do the reverse. I set my wifi hotspot or bluetooth to "MetPoliceUnit355" and I look for people making faces or looking around.

by mytailorisrich

2/16/2026 at 6:00:59 PM

This is not very different from collecting visual cues. You can notice a delivery van arriving. You can see the driver's face, same with passers-by. The biggest difference is that a camera needs to be more conspicuous, while a BT receiver can be invisible and undetectable. Much cheaper, too.

by nine_k

2/16/2026 at 10:36:47 PM

I have an ESP32 Cam in front of me right now. I think I paid maybe 8 bucks for it. If I wanted to, I could very easily hide the tiny camera in my front door, and use it to both collect bluetooth and wifi metadata (including MAC addresses) and correlate images/faces to MAC addresses when people pass by close enough so that I can identify them later from longer range wifi/ble detections.

(I actually do plan to install this at my front door, but aimed mainly to detect when a deliver/parcel in on my doorstep, and I don't (yet?) plan on sniffing bluetooth/wifi with it)

by bigiain

2/17/2026 at 12:34:18 AM

A decent optical part is comparably expensive, and somehow visible.

by nine_k

2/16/2026 at 6:15:35 PM

The part about passively detecting delivery driver patterns from a home office is wild. I knew BLE was chatty but being able to correlate device pairs (phone + watch) to build movement profiles with just a Pi is genuinely unsettling. Makes me want to audit which of my devices are broadcasting when they don't need to be.

by clarabennett26

2/17/2026 at 1:20:22 AM

I mean.. these services have apps right? It is, mostly, pretty trivial to track drivers and it would not surprise me if they have a fixed ID.

by thenthenthen

2/16/2026 at 4:29:07 PM

Bluetooth desperately needs mac randomization. Wifi mac randomization is welcome, but it doesn't do much when many (most?) people have bluetooth accessories broadcasting a persistent identifier whenever they're on.

by gruez

2/16/2026 at 6:32:32 PM

> Bluetooth desperately needs mac randomization.

Bluetooth already has a well developed MAC randomization scheme.

Lookup "resolvable private address". The short of it is, your phone can find your headphones or vice-versa, despite one or both having random addresses. The addresses can be regenerated or rotate at an interval (say 15 minutes). The first part of the address is a nonce (pRand), and the rest of the address is a 24-bit hash of pRand with an identity resolving key (IRK). So the other party just listens passively for addresses, and sees if any of them happen to have the right hash.

I don't think this is as airtight as people think it is. Certainly, if you are following somebody and one address disappears right as another appears (rotation), it's quite easy to infer the new/old addresses belong to one device. I tried briefly to convince the Android developers to synchronize that rotation globally.

You can also probably infer that if you see a pair of random MACs arrive, and they have a certain pattern of timing and payload size, you can say with some certainty that they are particular devices, say an iPhone and an Apple Watch. But that requires sophisticated equipment since most Bluetooth LE communication is over a non-cryptographic frequency hopping arrangement.

Lastly, radio fingerprinting is widely known in academia, but requires special equipment.

by avidiax

2/16/2026 at 10:43:33 PM

> Lookup "resolvable private address". The short of it is, your phone can find your headphones or vice-versa, despite one or both having random addresses.

Is that just for the connection phase? Or does it then start publicly broadcasting a persistent MAC onced it's connected, so if you earbuds or watch are connected and communicating with your phoine, would a sniffer see a persisten MAC address or the session randomised one?

That's a problam (one of many problems) with WiFi MAC address randomisation - you can sniff the network names a phone is trying to connect to, then stand up a wifi access point with one of those names and the phone will reveal its real MAC address when it connects. I experimented a long time back with having a raspi that broadcast itself as a McDonalds free wifi access point, a huge number of phones would try to connect while I was out in public with it.

by bigiain

2/16/2026 at 10:49:49 PM

>That's a problam (one of many problems) with WiFi MAC address randomisation - you can sniff the network names a phone is trying to connect to, then stand up a wifi access point with one of those names and the phone will reveal its real MAC address when it connects.

That's not how mac address randomization works now for both android and ios. Both connects with a randomized mac as well, which might be persistent per-network, but it still heavily hampers data collection. For ios specifically, it also seems to have some sort of heuristic to detect which network names are common/guessable, and use a rotating mac for those. Moreover "you can sniff the network names a phone is trying to connect to" isn't really a thing unless the network is using hidden ssid, which isn't the default for almost all routers.

by gruez

2/16/2026 at 11:06:53 PM

Oh cool, thanks. My last time playing with this was pre covid, possibly 5 or more years pre covid.

I do know for sure that my iOS devices connect with persistent MAC addresses on both my home and work wifi networks - I'd _assumed_ it was the same MAC address on both networks, but I'll be curious to see if that's correct next time I'm in the office.

by bigiain

2/16/2026 at 11:26:47 PM

You don't even need to be in the office to see it. Just go to wifi -> edit, and it'll bring up a list of saved networks. Tap on one of them and it'll show the mac address used.

by gruez

2/17/2026 at 1:34:18 AM

Thanks!

by bigiain

2/16/2026 at 4:51:05 PM

Random Bluetooth MACs are already possible. iOS devices have been doing it for years alongside the random Wi-Fi MACs.

by neilalexander

2/16/2026 at 8:55:21 PM

Ring: thank you for the idea, "Introducing Ring Face-Off, face masks covering faces during a break-in is no an issue for Ring, we will track the thieves until they reveal their face to our Ring network."

by dalemhurley

2/16/2026 at 10:48:53 PM

For immediate release: BLE N95 Facemasks Inc (YCombinator Summer 2025) is proud to come out of stealth mode and announce our acquisition by Ring. This follows a major private angel investment by Palintir with a post money valuation of $500 million.

by bigiain

2/16/2026 at 3:51:37 PM

About 10 years ago i had HomeAssistant running and thacking my bluetooth devices. It does so per default by jus memorizing a mac adress an recording when it's visible and when not. No need for pairing or anythung. It also stores the custom name if available.

Anyway, the default dashboard also automatically generated a view when my neighbours "Katie's iPhone' was at home and when not, until I actively deleted it and the data it stored.

by jeena

2/16/2026 at 11:15:26 PM

BLE Tire pressure sensors are great vehicle identification devices. Static MAC adress gives 4 unique keys to a vehicle when actively scanning.

by haberlerm

2/16/2026 at 5:35:42 PM

"We agreed on a 150-day disclosure window". Isn't that longer than Google Project Zero gives to release fixes?

by bpoyner

2/16/2026 at 6:28:00 PM

This could be used for a truly eye-opening art installation: a screen that as you walk by it, tells you when you were last there..

Even wilder would be to buy data on you in real time and display that.

by cadamsdotcom

2/16/2026 at 9:22:57 PM

I can assure you this has been talked about and is known and it's why you still find a headset port on devices handed out to government officials, though most of them ignore the advice to not use bluetooth.

by bigbuppo

2/16/2026 at 5:27:15 PM

ran something similar on a home network once and was surprised how many of my neighbors' devices showed up with full manufacturer names and model numbers. you don't even need to try hard.

by kevincloudsec

2/16/2026 at 11:36:54 PM

Yeah here in the city I scan for 2 minutes and I know half the neighbours names and what phones, computers and TVs they use.

by wolvoleo

2/16/2026 at 8:51:40 PM

you said " blocking ads network-wide with AdGuard". It's better to block it with a Pihole.

by f0r3st

2/16/2026 at 10:09:12 PM

Emit at your own peril

by fennec-posix

2/16/2026 at 6:20:45 PM

The project describes - and shows - a web interface.

Is there a simple CLI interface that can be redirected or pipelined into other tools ?

by rsync

2/16/2026 at 6:45:15 PM

The article says the data is in a SQLite database.

by kccqzy

2/16/2026 at 6:53:33 PM

Yes I see that and I wonder if the project includes a CLI tool.

by rsync

2/16/2026 at 3:37:14 PM

I suspect the e-scooters left around town (Lime, Bird, etc) are massive Bluetooth / LoRa dragnets. You pay them to increase coverage or visibility to social hot spots.

by jjbiotech

2/17/2026 at 1:22:25 AM

There is a startup (in Stuttgart i believe?) that adds camera ms to these scooters.. this is 100% illegal (and I think the ccc is filing lawsuits?). Some of the earlier Tier model scooters even had a dedicated space for a camera in their head tubes.

by thenthenthen

2/16/2026 at 4:17:01 PM

Wow e-scooter wardriving is something I hadn’t thought of. Could be happening somewhere

by hammock

2/16/2026 at 4:01:47 PM

Doesn't HackRF with Cha0s do something similar?

by webdoodle

2/16/2026 at 5:44:50 PM

And kismet

by HNisCIS

2/16/2026 at 8:23:52 PM

Wait doesn't BLE randomize the UUIDs?

by 0xdeadbeefbabe

2/17/2026 at 1:36:00 AM

Yes, I was surprised there would be enough to go on with the MAC addresses rotating and I had assumed the UUID would too, but it sounds like there's enough to go on to identify targets.

by nmstoker

2/16/2026 at 8:13:53 PM

> This isn’t about paranoia. It’s about understanding the trade-offs

> Bluetooth mesh networks—no internet required, no servers, no phone numbers

LLM slop. Both the article and the Python script

by catsquirrel28

2/17/2026 at 1:09:34 AM

I second that. This website, including its look and layout, appears to be a copy of some more prominent indieweb ones that have been frequently featured here, filled with what seems to be almost entirely copied and/or LLM generated content.

by the-anarchist

2/16/2026 at 3:23:32 PM

I read an article in 2012 about the feds (DHS?) placing Bluetooth enabled devices along I5 in Seattle. They were able to make profiles of people based on what Bluetooth devices they had in their cars. Is anyone familiar with this? I've periodically tried to Google it and can't find anything about it

by zoklet-enjoyer

2/16/2026 at 6:37:01 PM

Possible, but they buy data from the carriers with similar profile possibilities. The DEA operates long standing and pervasive surveillance in “drug corridors” like I-95 from Maine to Miami. They do things like LPR and grabbing passenger pictures.

If Bluetooth is used, it may be a way to get a count of passengers or if the passengers change. I know based on newspaper accounts that they are particularly interested in cars that stop in Philly or Baltimore.

This stuff is frequently used against cops too so they may use the tech in similar ways. If you’re someone worried about getting raided, spotting a large number of new signals at the front door is an early warning potentially.

by Spooky23

2/16/2026 at 3:37:23 PM

I remember an art exhibit by an online privacy activist made where it’d ping people’s phones to get a list of “known WiFi networks” and then display them on a screen in a room.

Each person would get a unique fingerprint of named network locations

by parpfish

2/16/2026 at 3:59:56 PM

I believe Houston used bluetooth to measure congestion on 45.

by post_break

2/16/2026 at 7:04:26 PM

Has anyone ever studied what happens with Bluetooth contention where thousands of people are gathered in a small space?

Like a marathon mass-start with 10,000 sometimes 20,000 or more people

How does bluetooth handle that? Or it doesn't?

by ck2

2/16/2026 at 8:33:52 PM

In my experience, just fine. I recently ran a large (~30k) marathon and my AirPods and watch never glitched once, streaming the whole time including in the packed start corrals. I had the same thought about RF contention, but Bluetooth didn't seem to care.

by username_here

2/17/2026 at 3:25:17 AM

https://en.wikipedia.org/wiki/Frequency-hopping_spread_spect..., combined with the inverse square law, is pretty amazing.

The amount of data needed to send audio to your ear-buds is quite small compared to the spectrum available, so only needs tiny slices of spectrum and for relatively tiny slices of time. And also relatively tiny amounts of power since it's only going max 100 feet, hence a pretty small chunk of space.

If all those 10K-30K devices are constantly jumping around the frequency band to transmit tiny payloads a tiny distance, then a whole metric fuck-ton of them can interoperate in what seems to us to be very tight quarters. But to those specialzied radios it probably seems like a fairly wide open field.

by just6979

2/16/2026 at 7:34:36 PM

Even licensed wireless stops functioning. All circuits are busy.

by supertrope