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Only if those SSIDs were configured as a "hidden SSID" (WifiConfiguration.hiddenSSID). AFAIK, that will only happen when you type the SSID manually, instead of
by cesarb 8y ago
Only if those SSIDs were configured as a "hidden SSID" (WifiConfiguration.hiddenSSID). AFAIK, that will only happen when you type the SSID manually, instead of selecting it from the list of scan results. And using a "hidden SSID" is a bad idea in the first place (https://superuser.com/questions/43836/automatically-connecting-to-hidden-ssid-wifi-network/48280#48280 https://superuser.com/questions/43836/automatically-connecti...).
- jsjohnst 8y agoThat is entirely not true, both iOS and Android send out requests for known APs when not connected to Wi-Fi. iOS does it VERY often in fact (depending on your list of known APs, could be upwards of 50x/min while device is in use). If you have a wifi chipset you can put in monitor mode, it’s easy to see how noisy mobile devices are.
- cesarb 8y agoI looked at it back in 2015 (https://news.ycombinator.com/item?id=9217589 https://news.ycombinator.com/item?id=9217589), it seems there was a bug (https://www.eff.org/deeplinks/2014/07/your-android-device-telling-world-where-youve-been https://www.eff.org/deeplinks/2014/07/your-android-device-te...) which sent these probe requests when the screen was off. I don't know if it has been fixed yet.
- jsjohnst 8y agoDon’t know about the bug you linked (will read up on it later), but I can easily provide radio captures to prove that most Android devices do what I described, with no “hidden” networks ever in use. There are retail analytics startups who literally use this exact type of data to allow brick and mortar stores to gain insights into their passive customer behavior. Source: I used to work for one of them and designed and built a bunch of the hardware / software stack.