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From: Woody on 27 May 2010 20:49 David Empson <dempson(a)actrix.gen.nz> wrote: > SteveH <italiancar(a)gmail.com> wrote: > > > Woody <usenet(a)alienrat.co.uk> wrote: > > > > > How does my new iPad (a 32GB wifi) know where it is? > > > > > > It isn't supposed to have a gps in it, even though it clearly has a > > > compass. > > > > > > It doesn't have 3G, so it can't read 3G towers like the first iPhone > > > did, so how does it know what road it is in, and where it is down the > > > road? > > > > > > Or is it something simple such as it knows my home address. > > > > It's some funkyness with the wifi signal, as I understand. > > The key to understanding how it works is Skyhook Wireless. They have a > massive database of WiFi base stations (identified by MAC address) and > where they are physically located. So it knows my MAC address in my private router, or next doors ones? > If there are any WiFi networks in range of the iPad, the MAC address of > those base stations are available to the iPad. (Even if the networks are > secured; the SSID must be broadcast to make this easy.) There are, the two network connections > If the iPad has an Internet connection (via WiFi), it can use the > Skyhook Wireless service to look up the MAC addresses of all the visible > base stations to see if any of them have been registered. If so, that > gives it an approximate physical location, to within about 100 metres > (assuming the coordinates of the base station are accurate). So what or who registers those addresses? Is this part of google tagging peoples personal wifi routers? -- Woody Alienrat Design Ltd
From: David Empson on 27 May 2010 21:53 Jaimie Vandenbergh <jaimie(a)sometimes.sessile.org> wrote: > On Fri, 28 May 2010 01:49:27 +0100, usenet(a)alienrat.co.uk (Woody) > wrote: > > >David Empson <dempson(a)actrix.gen.nz> wrote: > > > >> SteveH <italiancar(a)gmail.com> wrote: > >> > >> > Woody <usenet(a)alienrat.co.uk> wrote: > >> > > >> > > How does my new iPad (a 32GB wifi) know where it is? > >> > > > >> > > It isn't supposed to have a gps in it, even though it clearly has a > >> > > compass. > >> > > > >> > > It doesn't have 3G, so it can't read 3G towers like the first iPhone > >> > > did, so how does it know what road it is in, and where it is down the > >> > > road? > >> > > > >> > > Or is it something simple such as it knows my home address. > >> > > >> > It's some funkyness with the wifi signal, as I understand. > >> > >> The key to understanding how it works is Skyhook Wireless. They have a > >> massive database of WiFi base stations (identified by MAC address) and > >> where they are physically located. > > > >So it knows my MAC address in my private router, or next doors ones? > > Yes. Probably. Skyhook Wireless probably doesn't know it belongs to you (unless you registered it with them and gave them your details), just its MAC address and its geographic position to a reasonable level of accuracy (probably within 10 metres). This can of course be used to determine the owner's physical address, with some degree of error. There have been interesting issues such as their scanning picking up base stations situated on a vehicle of some kind. This can cause all sorts of amusement. I recall a case mentioned on comp.risks a while ago where someone's car navigation system in New York thought it was on the other side of the US, because Skyhook Wireless had recorded the location of a particular WiFi base station, and that base station was on a ship, which had of course travelled elsewhere, taking its "poison pill" with it. The navigation system corrected itself after they drove away from the harbour. I have no idea if anything was done about removing that particular base station from the database. > >> If the iPad has an Internet connection (via WiFi), it can use the > >> Skyhook Wireless service to look up the MAC addresses of all the visible > >> base stations to see if any of them have been registered. If so, that > >> gives it an approximate physical location, to within about 100 metres > >> (assuming the coordinates of the base station are accurate). > > > >So what or who registers those addresses? Is this part of google tagging > >peoples personal wifi routers? > > Not Google, that's another thing entirely. > > http://www.skyhookwireless.com/howitworks/coverage.php > > http://www.skyhookwireless.com/careers/drivers.php -- David Empson dempson(a)actrix.gen.nz
From: Richard Tobin on 28 May 2010 03:37 In article <1jj7f87.918kqwawp8vuN%dempson(a)actrix.gen.nz>, David Empson <dempson(a)actrix.gen.nz> wrote: >I recall a case mentioned on comp.risks a while ago where someone's car >navigation system in New York thought it was on the other side of the >US, because Skyhook Wireless had recorded the location of a particular >WiFi base station, and that base station was on a ship, which had of >course travelled elsewhere, taking its "poison pill" with it. You'd think they could have a sanity check - "don't assume supersonic travel on the basis of a single base station". If you drove past the the new University of Edinburgh Informatics building it would suddenly transfer you two miles south. presumably because an access point moved with the Computer Science department. And of course people move routers when they move house, sell them on Ebay, and so on. -- Richard
From: Woody on 28 May 2010 03:49
On 28/05/2010 02:53, David Empson wrote: > Jaimie Vandenbergh<jaimie(a)sometimes.sessile.org> wrote: > > There have been interesting issues such as their scanning picking up > base stations situated on a vehicle of some kind. This can cause all > sorts of amusement. > > I recall a case mentioned on comp.risks a while ago where someone's car > navigation system in New York thought it was on the other side of the > US, because Skyhook Wireless had recorded the location of a particular > WiFi base station, and that base station was on a ship, which had of > course travelled elsewhere, taking its "poison pill" with it. > > The navigation system corrected itself after they drove away from the > harbour. I have no idea if anything was done about removing that > particular base station from the database. So I assume its accuracy is set to plummet soon then. At work I can see three mifi's, and they are getting a lot more common -- Woody |