With WPA2 security enabled, it's unlikely anyone will ever piggyback on your network. But there's an easy way to spot squatters: Since every device connected to your network has a unique IP address and MAC address, you can easily see a list of connected devices — often listed as "clients" — on one of the settings pages for your wireless router. Many devices broadcast an ID because they've been named by their owners, so if you see "John's Laptop" connected to your network and you don't have a John in the house, you've found trouble! Even if a device doesn't show a name in the router's client list, you can count the number of devices connected and compare to the number of devices you know should be there to see if the numbers are off.
Want to make absolutely sure no one's going to figure out your password and worm their way onto your network? You have a few options. Your router can hide its SSID, meaning it won't show up for anyone searching for connectable networks. The address will have to be entered manually.
You can also set up a wireless MAC filter to "whitelist" devices you own, disabling access for anyone else. Of course, this makes it a bit tougher for welcome guests, such as friends, to get online at your house.
But that still leaves the burning question – what do you do if you think someone is routinely using your WiFi without your permission?
If you suspect someone's stealing your WiFi, you have a number of detective tools at your disposal. For starters, you could simply shut off all of your WiFi devices, like your phone and your laptop – and then watch for blinking lights on the front of your router. If the router seems to be showing data transfer even with your family's devices powered down, you may have a piggybacker nearby.
You can also smartphone apps like WiFi Thief Detector or for iOS users, WiFi Guard, which help you spot intruders.
Internet monitoring software is another option. A program such as Wireless Network Watcher lets both Windows and MacOS users keep tabs on all connected devices and potential suspicious activity. When you launch the program, you'll see your computer nicknames, as well as manufacturer brands of the devices that are connected. If you're still confused (perhaps because you have so many devices), you can turn off each one and watch as it disappears from the list. If you power down all of your WiFi gadgets and still see active devices, you're a step closer to identifying a potential problem.
If you can't identify a device on your network, simply change the password. You'll have to reauthorize all of your WiFi devices with the new password, of course, but this is quickest and easiest way to resecure your network and get peace of mind [source: Gordon].
As long as your network has a strong and unique password, only a hacker using specialized software is going to get past your security. A simple Google search will reveal just how many password hacking resources are available to criminals.
For example, technology site Ars Technica has detailed how a $2,500 program called Silica can be used in conjunction with websites containing dictionaries of millions of words to connect to a secured network and crack its password.
Hashcat is another popular password hacking tool. Like Silica, it's paired with databases of millions of the most popular password combinations until it figures out the correct password. It works – and it's extremely easy to do, even for novice hackers [source: Porup].
But there's still an effective and efficient way to stop most hackers in their tracks: Use a secure password. The longer and harder to guess, the safer your network will be. With a strong password, you shouldn't ever have to worry about keeping tabs on who connects to your network. Piggybackers will have to find someone else to mooch off of.
Originally Published: Apr 30, 2009