Google gathers the information via Android phones, in the same way that Apple gathers the information via the iPhone, and Microsoft does via Windows Phone 7 devices. (It only gathers the information if people have opted in to use Google location services.) Information about WiFi network locations are sent to Google, which then uses that information as part of its location-based services for mobile devices. It's been a controversial program, notably because at one point Google didn't just map the networks, but actually gathered information transmitted over those networks, including private email.
Since that revelation, Google has faced legal pressure, especially from the European Union, to kill the mapping service, or let people opt out. Back in September, Google announced that it would eventually allow people to opt out of it. At the time, Google also said it wouldn't appeal an edict from the the Dutch Data Protection Authority (CBP) to destroy records of 3.6 million Wi-Fi hot spots.
Yesterday, on its blog Google made it official --- you can now opt out so that your Wi-Fi hot spot won't be included in Google's database. But plenty of people who may want to opt out may have no idea how to do it. Here's how to do it.
You'll need to add the text _nomap to the end of your network's name, what's known as its SSID (service set identifier). So, for example, if your network's name is Mianet, you'll have to change it to Mianet_nomap.
If you're like a lot of people, you may not have even changed the default name of your network, and it may still have the name it had when you bought it, for example, Linksys for a Linksys router.
How you change your network name varies according to your wireless router, but the same general steps apply to all. You log into your router's administration page, head to the wireless section, rename your SSID, then save your changes. Here's how to do it on a Linksys WRT160N; similar steps will apply to your router.
1. Log into your router with a Web browser. You'll need to know your router's IP address on your network in order to log into it. For Linksys, it's typically 192.168.1.1. For Netgear routers, it's usually 192.168.0.1 or 192.168.1.1.
2. Type in your user name and password. You'll come to a page asking that you type in your user name and password, so go ahead and do that. Routers come with these by default, so if you haven't changed yours, check your system documentation for the default. On Linksys, by default, leave the user name blank and use the password admin.
3. Go to the wireless administration page. How you do this varies according to your router. On the Linksys WRT160N, click the Wireless tab.
4. Change the SSID and save your settings. Look for the Network Name (SSID) setting. Add the text _nomap to the end of it. Then click Save Settings.
5. Reconnect all of your wireless devices. When you make the change, all of your wireless devices will lose their connection to your network. So you'll have to reconnect them all, using the new network name.
Note that many routers can also turn off SSID broadcast --- in other words, it won't broadcast your router's name to the world. Theoretically, this may keep Google from finding it. But if they're already found the SSID once, it may already be in the database, and they might find it again. Theoretically, changing the SSID name and having your router not broadcast the name might keep it out of Google's clutches as well. You usually turn off SSID broadcast on the same page where you change the SSID name.
Google, by the way, has a Help page about its Wi-Fi tracking, including links to various manufacturers that give some help about changing your SSID. Check it out here.
Note: A previous version of this blog incorrectly reported that Google gathers WiFi information via the cars sent out for Street View. That used to be the way Google gathered the information, but it no longer does that. Instead, it uses the information sent from Android devices.