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.
Internet monitoring software is also an option. For example, free utility AirSnare will alert you when unfamiliar MAC addresses log onto your network. But with a secure connection, you shouldn't have to worry about that. The truth is, WiFi is not a precious commodity like it once was. You can get it at practically any coffee shop. Millions of us carry around smartphones with always-on data connections. To some degree, that makes WiFi access a faster, cheaper option of Internet access, but it's not always the most convenient one.
As long as your network is passworded, only a hacker using specialized software is going to get past your security. Technology site Ars Technica has detailed how a $2500 program called Silica can be used in conjunction with Web sites containing dictionaries of millions of words to connect to a secured network and crack its password [source: Ars Technica]. But there's still an easy way to stop even serious hackers in their tracks: Use a better 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.