White noise

The ghostly chatter of neglected computers is getting louder. And it could spell the end of the Net as we know it

The internet's watchmen have discovered that their network tumbled into the world with a potentially fatal birth defect. The cause? "Background radiation". The constant chatter of machines that lie awake while we sleep, and their long memories, pose a threat to future health of the system.

Some of the internet's most senior figures now think this issue needs urgent attention. Karl Auerbach, one of its pioneering technicians, wrote last year: "There are indications that the internet, at least as we know it today, is dying." He was referring to the flow of "junk" traffic; a sort of background static in the world of the Net. Unnoticed by you or me, it is the result of neglected machines making eerie "zombie" calls.

The problem is that while we expect machines to work smartly, the internet was designed with stupidity foremost. Stupidity - that is, a small pool of shared assumptions about the world, and a tiny pot of residual trust - is baked into the architecture of the internet, and was valued by the its sponsor, the US Department of Defense, which wanted a protocol malleable enough to create a network that would work after a nuclear attack.

These values proved to be smart decisions for the durability of the internet, which until recently was just one style of networking computers. Some rival systems learnt where computers were and trusted them to stay there. But the Net's basic protocols don't; instead, they show the paranoia of the terrorist cell: zero trust and short timeouts before they decide that the machine being contacted has vanished. This has its consequences, and they are not always good.

A rookie postman soon learns that on the high street, Woolworths is located next to the Virgin Megastore, and isn't about to disappear. So if he has post for Woolworths, he takes post for Virgin, too. He learns to cut out redundant journeys and makes calculations to rectify mistakes. But on the internet, omniscient calculations aren't possible. On the internet, the two "stores" don't know they're next to each other. As their internet protocol is programmed to do, they chatter constantly, sending each other "are you there?", and "yes, I'm still here" messages. "The traffic that continues include e-mails, remote file system mounts and printer requests," says Auerbach. "It's a hidden cost, a kind of shadow from past uses. Between viruses and spammers and just plain old bad code, the Net is now subject to a heavy level of background packet radiation."

Just as pointing radio telescopes at the night sky picks up the background radiation left over from the Big Bang, so connecting any machine to the Net picks up this static. The trouble is, it's getting louder. Why? The Net has very long memory. "Search engines still come around sniffing for web sites that disappeared, along with the computer that hosted them, and the IP address on which that computer was found long ago."

The radiation is there even if no computers are active. It's the price of being attached to the internet. Simply maintaining a network of 64,000 inactive, unplugged computers costs a provider around $1,300 a month at current US wholesale bandwidth prices. And if those computers are turned on, then the amount of static, and the cost, trebles to around $4,000. And that's before a single user has typed in a web address, or performed any other activity.

Robin Bandy, a system administrator for a Californian ISP, provided a rare insight into zombie activity by charting what happened to a computer that was reachable, but dead, over eight months. Although the machine was turned off, the unique number was still receiving chatter that passed through Bandy's Cliq network.

The end-point received an average of 20 bits of traffic a second, rising to 60 bits a second when the machine was turned on and responded to the incoming chatter. That doesn't sound like much compared with the floods of junk e-mail we receive: 60 bits, seven and a half bytes, barely enough to represent the word "zombie". As users, we hardly notice it. Today's dial-up modems typically send and receive around 800 times as much per second, so the radiation isn't going to choke your home computer. But for an ISP, it's significant - and, as the figures above show, expensive.

Packet analysis conducted for The Independent showed that over a three-week period, a quarter of the traffic consisted of enquiries aimed at finding holes in Microsoft's database server. This popular target was responsible for propagating worms such as Blaster. Spammers consistently attempted to coax the machine into sending spam on their behalf, too; spammers often send their messages from a hijacked machine, without the owner realising it.

So what causes the radiation? "It's either malicious or a mistake, and mistakes are very rare," says Bandy. Auerbach doesn't quite agree, saying neglect is a contributing factor. "Some dufus out there has a Windows machine that believes that that IP address is still the home of some server that lived there sometime in the past."

Meanwhile the internet's most-publicised problems - spam e-mail and worms - compound the problems because the crude countermeasures introduced to thwart them have backfired. "Spammers who use an address temporarily and then move on create a legacy of addresses that are on various anti-spam blacklists. Unwary users pick up these addresses. Sometimes those users don't notice," says Auerbach. "But sometimes they experience trouble and absorb the frustration and costs. Sometimes they call their ISPs and let the ISPs burn money and time trying to figure out why the user's IP address is weird."

The problem can multiply through neglect. When a malevolent individual creates a "denial of service" attack, administrators retaliate by quarantining the areas of the internet where the attack is coming from. If the quarantines aren't lifted, the internet effectively has black holes of unreachable banks of computers.

The internet is commonly held to be inclusive, all-welcoming and free of attempts at social conditioning. Alas, the messy reality gives lie to that. "The Net is Balkanising," says Auerbach ruefully. "Communities of trust are forming in which traffic is accepted only from known friends."

The pollution problem and how we deal with it should put paid to cybernetic utopian notions of a "self-healing" fabric of machines. Like terrestrial pollution, it will need human intervention and action into awkward problems of governance that both engineers and politicians have been reluctant to grasp.

Andrew Orlowski is the US editor of 'The Register', based in San Francisco