Researchers Take 'Internet Census'

For the first time, researchers have conducted an Internet census by mapping the Web's nearly 3 billion assigned IP addresses, an effort that could provide important clues to how to fight computer viruses, according to the University of Southern California Information Sciences Institute.

The researchers hope to discover how Internet worms spread through computers across the globe and to get a clearer understanding of how to expand the Internet's capacity. If left unchecked, the growing number of users and IP addresses threatens to limit Internet access by 2010.

The ISI has performed about 17 versions of the census since 2003, but the notable difference in the latest version is that it's the first time researchers have developed a visual representation of it.

"My research group has been exploring how to understand the Internet and how to interpret network traffic. So we realized that it was actually feasible to take a census," said John Heidemannn, a senior project leader at the ISI and a research associate professor in the computer science department at USC. "We worked out how to do that and we're trying to understand the data we've collected."

The census, which was funded by the Department of Homeland Security and the National Science Foundation, was conducted when the team sent an Internet probe, also known as a "ping," to the 2.8 billion IP addresses currently in use.

An IP address is a unique, permanent 10-digit number assigned to nearly every piece of hardware that taps into the Internet.

When the probes contact IP addresses, the addresses automatically send a response signal back to the origin of the probe, allowing the researchers to record the results. As the addresses responded, Heidemann and colleague Yuri Pradkin began mapping them according to their numerical location on a grid. What resulted was a clearer image of computers and other devices that use the Internet all over the world.

It took Heidemann 62 days to send messages to each of these addresses and several more days to develop the graphs of the addresses.

"There are many purposes one could use this data for," Heidemann said. "One purpose is trying to better understand Internet security."

Like the "pings" Heidemann sent out, Internet "worms," viruses that replicate themselves, probe IP addresses randomly. Those not protected by firewalls might be vulnerable to worms.

"Understanding how [IP addresses are] used and allocated, we can better understand how worms might spread," he said.

But computer security isn't the only reason to explore the Internet's addresses, according to Heidemann.

In the current system, there are a limited number of IP addresses -- just more than 4 billion. If we run out, which some experts predict could happen as early as May 2010, some users might be unable to tap into the Web.

Although a new system under development would make more and longer addresses available, it has been slow to catch on, according to the researcher.

"We have more than 4 billion [IP addresses], so less than one per person," Heidemann said. "I think users of the Internet are starting to realize that this is a problem that they're going to be facing soon. My hope is that our data will help shed some light on this challenge."

The Institute plans to continue performing censuses to keep track of how addresses are used and how fast the Internet is growing.

"The work is still ongoing," he said.