Bridging the gap: Beat the wi-fi black holes
You can use three methods to extend the range of your wireless network, with the goal to fill any "dead spots," or simply to add areas where a single wireless gateway can't reach.
Wardriving: When wireless insecurity strikes
"How did you know that name?" asked a concerned-looking Debrann Schad, an Oakland, California-based contractor, whose trip to the garbage can was interrupted by my question. "Only four people in the world know that nickname."
I'd found the name (which Schad asked me not to publish) using a wireless-enabled Pocket PC outside her house. Schad's gateway, located inside her home, was spilling Wi-Fi out to her curbside. The gateway had been set up in such a way that its identifier, labeled with Schad's high school nickname, was broadcast to anyone who happened to wander within range.
Though Wi-Fi is designed to work over short distances, folks who live or work adjacent to a Wi-Fi network (or who simply sit in a car near one) may be able to "borrow" access and use the wireless network.
Some Internet users scope out unprotected wireless networks (an activity known as wardriving) just for sport. A few Web sites publish maps that show the locations of open networks, with data provided by users who drive around and collect the information, using GPS-enabled laptops and software such as NetStumbler or Kismet. A search on WiGLE can yield anything from a handful to hundreds of listings of unprotected Wi-Fi networks, depending on the geographic location you search.
Using a pricey tool for network administrators called AirMagnet and a Pocket PC handheld, I saw her network identifier, or SSID, the brand of gateway she was using, the channel it was broadcasting on, and the fact that it was unencrypted.
In Schad's case, the risk was moderate. A friend had set up her network; Schad relied on it only occasionally, and never used it to check mail or shop online. But the friend left the gateway's default passwords enabled. Anyone nearby could have logged in, using the password published in the gateway's manual (and widely available on the Internet to those who know where to look), and altered her network settings.
If someone had deleted her DSL log-in, for example, Schad would have lost Internet access. An intruder could have set up WEP encryption, locking Schad out of her own network.
The risks would not have stopped there, however. A wardriving passerby probing Schad's local network would have discovered a networked printer and her PC, connected by wires to the gateway. Schad didn't have Windows' built-in file sharing enabled, but if she had, the snoop would have been able to root around in the files on her computer. A vandal could also have used up all the paper in Schad's networked printer, or could have printed obscene messages or images. And if a worm or a virus had placed a Trojan horse on her PC, someone could have remotely controlled it.
What can a Wi-Fi user do? "People, turn your security on, please," says Wi-Fi Alliance spokesman C. Brian Grimm, in a tone of mock exasperation. "At a bare minimum, change the default settings, like the SSID and passwords, and password-protect your shared drives, if you have any."