By Mark Ward
Technology Correspondent, BBC News website
Home network hardware supplier D-Link has been accused of harming the net's ability to tell the time accurately.
Accurate clocks are important for many net functions
Detective work has found that many D-Link routers, switches and wireless access points are bombarding some net time servers with huge amounts of data.
Time servers help many net functions run smoothly. For instance they have a role in deciding who made the last bid in eBay auctions.
D-Link is now taking action after protests from time server overseers.
The problems caused by D-Link hardware came to light thanks to Danish contractor Poul-Henning Kamp who runs Denmark's time server. Typically the time servers have links with atomic clocks to ensure they are as accurate as possible.
Mr Kamp said his time server started getting hit with a lot more traffic than usual in August 2005. Initially he thought it was a web attack as some viruses use web clocks to co-ordinate their activities.
However, digital detective work by Dr Richard Clayton from the security research lab at the University of Cambridge revealed that all the unexpected data was coming from D-Link hardware.
Mr Kamp said a new line of products sold by D-Link has the list of the net's time servers written into the software that keeps the devices running.
Further detective work has revealed the 25 or so D-Link products checking the time using this list.
The data flood is causing Mr Kamp problems because his time server is run on a non-profit basis and is allocated a small amount of bandwidth for the 2,000 or so Danish organisations that use it to tell the time.
The data flood has seen his bandwidth bill rocket and Mr Kamp is contemplating shutting the server down as he cannot afford the continuing costs. Now, up to 90% of his daily traffic comes from D-Link devices.
Accurate time-keeping is vital for many of the net's functions such as time stamping when people buy and sell goods via the net. Mr Kamp said one reason the Danish time server was set up was to help police get accurate timelines for some computer crime cases.
Mr Kamp said the responsible way to interrogate the time servers would be for D-Link to set up its own computer that can tell all its products the right time rather than have each device act alone.
Frustrated by his dealings with D-Link over the last five months, Mr Kamp published an open letter about the problems on his website.
This has revealed that D-Link hardware is also causing problems for 50 other net time servers. The list includes some run by the US military, Nasa, US research organisations and government groups around the world.
"My server is not the only one they are abusing," said Mr Kamp, adding that it was hard to get an accurate idea of the scale of the problem.
Accurate time helps sort out who won an eBay auction
"It could be millions of D-Link devices," he said, "I have no way of figuring it out."
A spokesman for D-Link told the BBC News website that the company was aware of "developments" but had no comment while it takes legal advice.
He said the company expected to issue a statement in the next few days.
However, Mr Kamp said that publishing the open letter appears to have re-started efforts to solve the problem.
Already D-Link has removed from its website, updates to the software that keeps its hardware running that contains the time server list.
"At least the problem's not getting any worse," said Mr Kamp, adding that pressure from other time server administrators could force D-Link to act.
It was unrealistic to expect D-Link to update the onboard software of all the hardware that is using the list of time servers, he said.
Instead, he would like D-Link to pay his bandwidth bills to ensure the Danish time server can keep going.