Stunning Visual Maps of Wireless LANs

By Ed Sutherland

March 27, 2002

Want to know how far your WiFi network actually goes? It may be farther than you think. Two Kansas University researchers can show you how to find out.

Borrowing a page from home energy conservation infrared scans, two Kansas University researchers have teamed up to map signals leaking from wireless networks. The maps have become the focus of nationwide interest in improving wireless security.

What began as a way for a university network employee to seek out rogue wireless networks has evolved into the Wireless Network Visualization Project. The project combines 'war-driving' and geography to create color-coded maps of the spread of wireless signals.

For the past year, Matt Dunbar, a geography graduate student working at the Kansas Applied Remote Sensing laboratory, and Information and Telecommunications Technology Center worker Brett Becker have scanned signals coming from 106 area wireless networks.

Stumbling onto Signals
Dunbar took the raw data collected from Netstumbler probes and used his knowledge of modern mapping techniques to give wireless users dramatic insight into how Wi-Fi networks easily extend beyond their intended range.

The maps, some available at the project's Web site, show high-resolution black and white aerial photographs with signal strength values coded in blue indicating where very strong signals were detected to orange, alerting network operators of very weak coverage.

The Kansas University duo says their work has drawn interest from commercial wireless firms looking to fine tune their networks to public access groups seeking ways to get a handle on their hotspots. One Lawrence hotspot discovered its signal stretched a square block beyond the cyber cafi hosting a network for laptop Internet access.

Maps Show Security Flaws
But the maps are benefiting more than just commercial interests. After learning 13 of the 14 on-campus wireless networks operated without encryption, Kansas University quickly began work on a new policy.

The Lawrence Police Department is using the maps to change its office Airport WLAN. The public, enamored with simple home networks, are getting another lesson in the need for using encryption -- passwords - or simply turning off the systems when not in use.

The equipment used to create the signal maps is easily found, said Becker. The project loaded their 1993 pickup truck with a laptop equipped with an Orinoco Gold WLAN card and Netstumbler software to scan and log detected signals. An omni-directional antenna and GPS unit rounded out the project's hardware.

Wireless Geography
Back at the university, Dunbar added high-resolution aerial photographs of the town plus the signal and GPS data to a Geographic Information System. Finally the signals were color-coded to shown their strength.


Dunbar doesn't see the maps becoming a commercial product, but plans to talk about his work at future academic and wireless conferences.

What's next for the wireless cartographers? Dunbar is thinking of a wireless security public awareness program, the possibility of cultural studies based on their data and updating the maps to show features in three dimensions. Becker wants next to investigate problems of interference from wireless networks. The two agree their next step will be expanding the project to nearby Kansas City.

Mapping Metricom
Far from the Kansas plains is Stanford University and Diane Tang, who, for her Computer Science PhD dissertation investigated how wireless networks are used. Her work, using high-end mapping tools, explored the actual - as opposed to theoretical - usage patterns of the wireless networks in San Francisco, including Metricom's Ricochet system. Instead of relying on signals sniffed from the air, Tang used network traffic logs as the basis for her maps.

As the number of cell phones, home wireless networks, and Wi-Fi hotspots grow, maps helping us find connection points and leaking signals will become as much an everyday, useful tool as road maps and energy audits.

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