Find my Mac - how does it work?

In follow up to my previous post on recovering my Apple computer, as an engineer passionate about networking, I was intrigued in how Find My Mac/ Find My iPhone actually works. Some of the devices have a GPS capability, some have a GSM/3G/4G capability, but my laptop has neither.

StackExchange explains the application using Wifi Positioning Systems (WPS):

The Mac can use Wi-Fi network identification for localization. This is called a Wi-Fi Positioning System (WPS). The access points name and signal strength is determined and looked up in a database to identify the location. The more access points are found, the more precise the localization. Unlike GPS (Global Positioning System) or cell-tower triangulation (together called Assisted-GPS), the Wi-Fi based localization works well inside buildings. There are different databases which collect wireless access points: Google, Navizon, Skyhook Wireless, OpenWLANMap. 

I have been pretty lucky that WPS pointed me to a single house. Now that all my devices are safely at home, the online version of Find My Mac places all devices in the shed in the backyard, on the border with my neighbors. I probably would not have known which house to send the SJPD to. ... unless I used the iPad/iPhone version.

I did discover that using the web-based version of Find My Mac is less accurate in pin pointing the device than using the Find My Mac application on an iPhone or iPad. On my iPad the application actually shows the address and can provide driving directions (which using Apple Maps may or may not lead you to the right location, but that's another story).

Note: At home WPS triangulation does work thanks to the neighbors networks. I actually do not broadcast my SSID. I thought this was a good security measure: if you do not know my network is around, you are not going to try to connect to my network. As this article points out, hiding your SSID isn't such a great idea for security reasons.

Revenge of the nerds

About five years ago, burglars visited our house. Due to the vigilance of a neighbor they were caught in the act, and all goods were recovered. A damaged door and a dent our safe home feeling were the only remainders from the ordeal. Last night, misfortune struck again.

One of the items stolen was a brand new Apple Mac Book Air family laptop. It was fully backed up, so essentially the loss of the laptop was limited to some electronics in a metal case. An expensive metal case nevertheless.

Today using the iCloud Find My iPhone of Mac application, the tide turned.  At 10:28am, minutes before our company board meeting, the Macbook Air popped up on the iCloud browser window. It was located in East San Jose. The first picture showed a radius of a couple of houses. That wasn't a lot to get the San Jose Police Department excited about. I called them nevertheless. They requested I drive to the area but remained a couple of blocks of the houses and show the police officer the tracking information.

In the interim, I was able to take some action. The Find my Mac application allows you take control of the remote device: you can lock it, you can play a sound or you can even erase the Mac. I opted for locking it, without alerting the user (no sound or message was displayed). Apparently for iOS devices you can request it to send you an email when it comes online, so you don't have to poll it all the time.

To a novice user, this renders the laptop unusable.

By the time the board meeting was over, the iCloud application had narrowed the location to a single specific house. I am curious to how it was able to do this, especially since the user was locked out of the laptop anyway. I also got the IP address but wasn't able to tie that to a specific house. If somebody knows, let me know.

With this information, I sped down to the area, drove by the house twice to check it out. There wasn't any sign of life in the house. I met up with the San Jose Police Department a few blocks away. Three SJPD officers showed up. After explaining them how iCloud Find my Mac works - this was new to all three officers- , they were convinced and requested me to follow them to the house. Adrenaline, Camera, Action!

After surrounding the house, making contact with the person living there, and a long 10 minutes waiting in the car, they came out with two devices: a iPad mini (not mine) and my MacBook Air. The NASA Curiosity sticker had been removed and will be restored. Victory is mine: I got my laptop back. Revenge of technology, revenge of the nerds!

Yes, this is absolutely a plug for Apple and the Find my iPhone/Mac application. Thanks to the SJPD to follow my lead to the house and recover my laptop. I offered them gladly some training on the tracking application.

Thanks SJPD! 

Epilogue - Unfortunately, the person who was in possession of the laptop, wasn't the person who stole the laptop. He bought the $1100 laptop less than 12 hours after it was stolen, in a tire store parking lot for $150. He was interviewed for close to an hour, the house was turned upside down, but nothing else was found.