Check If Someone Is Using Your Wi-Fi

It may be that you're experiencing a slower than normal Internet connection or you simply don't want anyone getting a free ride while you pay the bill. Of course, there are also security implications if this person can somehow access files on your network, and even legal implications if he uses your connection for piracy or other illicit activities. Whatever the case it's better

to stay on the safe side. Many of you may have already taken some basic precautions when setting up your wireless network and know your way around troubleshooting these issues. This brief guide is aimed mostly at novice users in need a hand to find out if, indeed, their Wi-Fi is being stolen.

Check the devices associated with your router

The first thing you need to do is login to your router's administrative console by typing its IP address directly into the browser address bar -- typically 192.168.0.1 or 192.168.1.1 or simply go to the command prompt (Start > Run/Search for cmd) and enter "ipconfig". The address you need should be next to Default Gateway under your Local Area Connection.

Next, point your browser to that IP address and enter your login details. Once inside your router's administrative console look for a section related to connected devices or wireless status.

This should provide a table with the IP, MAC address and other details of every device currently
connected to the router. Check that list against your gear to find any intruders. You can find out
MAC/IP address of your computers by going to the Command Prompt again and entering 'ipconfig /all'.
The MAC address will be shown as the physical address. I'll let you figure it out for mobile devices
like smartphones and media players since I can't possibly list all options.

Taking action

The best and simplest solution is to set up a strong password using WPA2 or WPA -- WEP is very easy to crack so avoid that if possible. There are some other methods you can use to beef up security, like switching off the SSID broadcast (which prevents it from advertising the name of your network to nearby Wi-Fi devices) or setup a filter for allowed or blocked devices by MAC address. It won't stop the most determined intruder but it will slow him down.

Needless to say, we're not suggesting you take matters into your own hands, but it might come in handy if someone is getting you in trouble with authorities using your network for illegal purposes -- or simply to have a cool story to tell.