Increase Security by Removing Old WiFi Networks

With your computing device (that's the generic term for anything with a processor, memory, operating system, and software - including phones (smart or dumb), tablets, computers, set top boxes, gaming consoles - heck anything nowadays, even your toaster!), chances are if you move it around, you are joining various WiFi networks.  What happens when you join a WiFi network?  The "computer" stores the configuration for connecting to that WiFi in the future, and automatically reconnects when something with the same name is available.  For example, let's say I buy a Linksys WiFi router for my home, and I leave the default name or SSID "linksys."  I join my laptop.  Now, let's say I drive out somewhere, park my car, and fire up my laptop to work on a Word document.  If someone nearby also owns a Linksys router (any model) and left it on the default name, my computer will connect without asking me (thinking it is a recognized network).

Why is this bad?  Let's say a hacker knows this, and sets up a network called that, or called "AT&T WiFi" or "Starbucks" or any myriad of commonly-used SSID names.  Many devices will connect to it automatically, and voila, he can watch the traffic going across his network, and possibly even hack into that device (computer, phone, etc.).

Are you worried yet?  You should be.  There are things you can do, however, to help limit the chances of this happening.

1. Pay close attention when you are joining a new network.  Some devices show a different icon if the network is a normal WiFi router, versus a mobile hotspot (in other words, using someone's cell phone to set up a WiFi hotspot would show as a different icon).  If this is the case, and you didn't intend it to be a personal hotspot, then don't join it.
2. Verify with the store or hotel you are at, what their WiFi name is.  Maybe there are several listed that are spelled similarly.
3. Frequently review the list of saved WiFi connections you used in the past, and delete any one you think you will never use again.  Below are instructions for how to do this in various devices.

Windows

In Windows 7, 8, or 10, go to Control Panel, Network and Sharing Center, and click Manage wireless networks (one way to get there is to click on the network icon in the tray, and pick "Network and Sharing Center" from the pop-up menu):

Then, select the network from the list, and pick the Remove button:

Android

For Android devices, go to the Settings app, go to WiFi, and simply tap the network in the list, you will have a Forget button to remove it from your list:

Apple Mobile (iOS)

For iOS devices, go to Settings, WiFi, and tap the little Info "i" button next to the network name.  There will be a "Forget this Network" option

Apple Macintosh (OS X)

For a Mac, go to Network Preferences (you can get there easily from the WiFi logo on the system menu).  Make sure to unlock the preferences for changes, and then click Advanced:

Finally, locate the network or networks you want to delete (hold down Command to select multiple), and pick Remove.  Confirm with the dialog to remove them, and click OK.

Finally, don't forget to click Apply to save your changes.

Note that you will have a similar thing for Apple TV, Roku, or any various TV devices, although you may not travel with them, and therefore probably don't join networks.  But if you do, think about it.