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Comment by qubex | Hacker News Reader

Pretty obvious, and pretty trivially circumvented by not sending traffic over the in-store Wi-Fi network. (Do such things really exit?? Never seen one here in Italy)

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In-store Wi-Fi is very common here (UK), and sometimes the only way to get a data connection because mobile signals can't penetrate the building. Only way around it at that point is a to use a VPN over their Wi-Fi if you can.

Big If :/ it's quite common for vpn to be blocked. Sainsbury's definitely blocks OpenVPN.

Use stunnel on port 443 - makes it look just like HTTPS traffic.

Well, even though most stores don't acknowledge it, how much do you want to bet there are stores that install 3G/4G cell jammers to prevent you from using your mobile to look up anything while in-store? I know a few places I shop where my cell coverage "mysteriously" drops to nil inside the store and I have long suspected it's not just the concrete walls.

That'd be illegal, so I kinda doubt it. Not to mention that jammers are pretty easy to detect with the right equipment so it'd be fairly easy to prove if they were doing something like that.

The FCC comes down HARD on anybody doing that. https://www.fcc.gov/document/marriott-pay-600k-resolve-wifi-...

If you suspect cell jamming, and you're in the USA, contact the FCC and report the business. The mere fact that it interferes with 911 is enough to send a store manager to prison. If they can prove that an emergency vehicle every got close enough to the business to be potentially affected, the business could see hundreds of thousands of dollars in fines.

The FCC could just park a van in front of the store for 3 minutes and their tools would verify that a jammer was in use.

Here's the details on anti-jamming laws, and a list of people who have had their ass handed to them by the FCC for doing it: https://www.fcc.gov/general/jammer-enforcement

Good to know this. I don't think it's outright cell jamming but something where voice service is still passable but data service basically cannot function due to packet loss, etc.

Would be interesting to try to detect if such interference is present on the right frequencies, or if it is just a natural effect and truly not intentional.

Thanks for sharing the info.

> something where voice service is still passable but data service basically cannot function due to packet loss, etc.

That pretty much describes 99% of indoor mobile coverage out there. The only exception being buildings that have ponied up for a femtocell.

> Well, even though most stores don't acknowledge it, how much do you want to bet there are stores that install 3G/4G cell jammers to prevent you from using your mobile to look up anything while in-store?

Actual jammers? Unlikely because it's highly illegal, quite detectable, and will cost more than anyone could hope to gain by it.

Deliberate, passive measures that practically impede indoor reception may happen, though.

>Deliberate, passive measures that practically impede indoor reception may happen, though.

It does seem that some buildings are suspiciously effective Faraday cages while others are not.

Yes, this is exactly the effect I am talking about. You go into the store, and effectively, using the cell network for data goes to zero, but the cell voice service still works.

Could it be something that makes the cell network jittery or adds latency that interferes with cellular data but not voice service?

Exactly: in some countries LTE coverage is so good that I for instance find the Wi-Fi function in my iPhone unnecessary and annoying and keep it turned off most of the time (to avoid my iPhone asking me stupid questions like which Wi-Fi I want to connect to - the answer is usually "none")

You know you can turn off the "ask about connecting to open wifi network" thing right?

I still turn off WiFi when I'm not at home though. Never need it unless it's one of those things iOS is unreasonable about (downloading large apps, syncing photos)

I never see it in Canada, we only have it commonly in restaurants & malls. But not box or grocery stores.

Strange, as a Canadian Save-On-Foods (primarily BC) shopper, I regularly use their in-store WiFi.

It's starting to appear. WalMart has instore wifi that I can never get to actually work. Fortinos and other PC grocery stores have in-store wifi now. Actually seems more consistent than the mall.

Every Metro I've been to seems to have it.

It's not necessarily obvious if they're just tracking your behaviour on WiFi and making external actions based on that (approaching you in store, or sending certain promotions).

I think a lot of people don't appreciate that you really need to trust to a WiFi network you connect to.

Yep, a lot of places in the US have their own Wi-Fi, especially in malls.

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