"Detectives arrived last summer at a high-rise apartment building in Arlington County, warrant in hand, to nab a suspected pedophile who had traded child pornography online. It was to be a routine, mostly effortless arrest.
But when they pounded on the door, detectives found an elderly woman who, they quickly concluded, had nothing to do with the crime. The real problem was her computer's wireless router, a device sending a signal through her 10-story building and allowing savvy neighbors a free path to the Internet from the privacy of their homes. ..."
This is a cautionary tale for all who use wireless technology in their homes. There are several things you can do to cut down on illicit use of your home network.
First is to filter based on hardware address of your network interface. By allowing only certain addresses to attach to your network you reduce greatly the chances that someone parked out front or living next door can tap into your service.
Second is to not advertise your network name (and make it obscure). When you scan for available wireless networks only those wireless access points that advertise their name are visible. Note that there are default names provided by the manufacturers and these are well-known to the signal thieves.
Third (and in my opinion the least effective) is to use WEP key. These are strings that serve to perform weak encryption on your wireless packets. The major problem is that at some point during the wireless connection negotiation that key is broadcast in the clear, and someone with a wireless packet sniffer can get all the information needed to attach to your network.
And a fourth suggestion is to change the default password on your web interface (which are also well-known). Make the password a good one.
Read the manual that came with your wireless access point/router and take the time to protect yourself.