I have an iMac (Mid 2011, if it matters) and I just installed Mavericks.

When I launch the Maps app, it knows PRECISELY where I am, which I could certainly understand if it was using IP geolocation. The catch is, I'm on a VPN connection, with the exit about 200 miles from my actual location.

If I use any of the IP geolocation websites, it shows my location at that VPN exit node, not where I actually am.

So, how DOES my computer know where it is?


Technically - the process is called trilateration and operates by cross checking all BSSID - the unique identifier / MAC address for each wireless base station that your Mac can detect while it listens periodically or is actively searching to join a WiFi channel.

You can run this scan manually by running the Wireless Diagnostic app which is located in /system/Library/CoreServices/Applications on Mavericks.

Wireless Diagnostic

As long as your hardware is within range of one hot spot that has been geolocated in Apple's database of hotspots, the location should be within one football field of the location of the hotspot.

With three or more measurements - and relative signal strength of the various hot spot radio signals - the program might be able to make a more accurate estimate of your location.

You can also run this scan from the command line using the airport binary that is squirreled away in

mac:bin mike$ airport --scan
                            SSID BSSID             RSSI CHANNEL HT CC SECURITY (auth/unicast/group)
                     na ala hele 00:26:36:9c:32:23 -59  2       Y  US WPA(PSK/TKIP/TKIP) WPA2(PSK/AES,TKIP/TKIP) 
                     na ala hele 00:26:bb:79:23:1f -59  2       Y  US WPA(PSK/TKIP/TKIP) WPA2(PSK/AES,TKIP/TKIP) 
                fast na ala hele 00:26:bb:79:23:20 -74  149,+1  Y  US WPA(PSK/TKIP/TKIP) WPA2(PSK/AES,TKIP/TKIP) 
mac:bin mike$ airport --getinfo
     agrCtlRSSI: -75
     agrExtRSSI: 0
    agrCtlNoise: -86
    agrExtNoise: 0
          state: running
        op mode: station 
     lastTxRate: 81
        maxRate: 300
lastAssocStatus: 0
    802.11 auth: open
      link auth: wpa2-psk
          BSSID: 00:26:bb:79:23:20
           SSID: fast na ala hele
            MCS: 4
        channel: 149,1
mac:bin mike$ ls -l /usr/local/bin/airport 
lrwxr-xr-x  1 root  wheel  89 Sep 13 11:40 /usr/local/bin/airport -> /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport
  • So, that makes sense, but now I'm worried that the anonymity that's supposed to attach to using a VPN for Internet access is not really worthwhile, since Apple (or whoever Apple feeds data to) could easily associate a MAC address to a physical location. In any case, thanks for the answers. – Binkleyz Nov 18 '13 at 18:38
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    I assume, but don't know for certain, that the OS X location code works in the same manner as iOS. It's opt-in, not storing any trackable data tied to you or your machine, and removed immediately on Apple's end when you opt-out of location tracking. You do want to opt out or disable all radios if you don't want your computer to know where it is located. – bmike Nov 18 '13 at 18:48
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    @Binkleyz If you do not need the WiFi, then turn it off. Without WiFi OS X cannot check for known BSSID to locate you. In this case, it can only rely on the IP address which can be unreliable, or in case of VPN can be wrong. :-) – Huygens Nov 20 '13 at 7:40
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    If you're paranoid about anonymity, then worrying that your operating system provider is learning your physical location is probably the least of your problems. Why stop there, when they could also be logging your keystrokes and sending all your personal data back to the mothership? Learning about the stuff in this particular question is good knowledge, but ultimately you have to decide if you trust your operating system and its provider. – chrismear Nov 21 '13 at 13:31

If you have Wifi turned on this happen because at least one of your close networks is stored in Apple's geolocation database.


It does not use your IP address, it analyzes networks around. The more networks you have, the better Apple knows where you are. This is because network in different locations can have the same name and Mi-Fi can be in different positions.


Turn of location services in System Prefs > Security and Privacy > Privacy. Remove check from Maps and now Maps will stop looking for your present location.


The iPhone 5S also includes a GPS chip. Your IP address is only one of the methods the phone can use to determine your location - others being triangulation of wireless base stations and cell phone towers.

  • The question is abourt a iMac not an iPhone – mmmmmm Nov 19 '13 at 21:31

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