According to the company, more than 20 million people have downloaded the new AVG 8, and this has caused a huge up-tick in traffic on sites across the web, including yours truly. Because the scanner attempts to disguise itself as a real live human click, webmasters who rely on log files for their traffic numbers may be unaware their stats are skewed. And others complain that LinkScanner has added extra dollars to their bandwidth bill.

Daniel Brandt, who runs Wikipedia Watch, estimates that LinkScanner traffic to the site has outstripped legitimate clicks by nearly ten times. In this graph, the pink line represents suspected LinkScanner scans, the blue line legitimate clicks:

When we first told the tale of AVG's fake traffic earlier this month, we pointed out that if webmasters were wise to the problem, they could filter LinkScanner visits from their log files. Each scan left a unique user agent: "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;1813)."

But over the weekend, the company changed this user agent on the for-pay version of AVG 8. It appears that scans now use these agents as well:

Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)

User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)

User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;1813)

Judging from the log files of two separate web sites, including Wikipedia Watch, the first agent is by far the most common. Which is bad news for webmasters. That's also the Internet Explorer 6 user agent. Unlike the other two - and the original "1813" agent - it's a perfectly valid agent that may turn up with real clicks.

AVG's chief of research Roger Thompson says the for-pay LinkScanner is only using the IE6 user agent. Presumably, the company believes this is more likely to fool malware exploits. "There are still ways for concerned web masters to filter LinkScanner requests out of their statistics," he told us over email. But he did not acknowledge that this could clip legitimate traffic as well.

Many webmasters may have no choice but to abandon log file analysis, adopting alternative tools from companies like Google, Yahoo!, comScore, or Nielsen NetRatings. And these tools have their drawbacks. comScore's service tends to underestimate traffic from daytime work machines. And if you go with Google Analytics, you have to tag your pages with JavaScript - and share your traffic numbers with Google.

Plus, these tools won't solve the bandwidth issue.

In an effort to fix this problem, one web master advocates redirecting AVG scans back to AVG's site. "Many webmasters simply tell LinkScanner to scan AVG's site instead, so their site gets marked as malware free every time - while AVG gets handed the extra bandwidth cost," says the webmaster of TheSilhouettes.org.

But this assumes that AVG is using a unique agent. And at the moment, it's not. The send-it-back-to-AVG method may redirect legitimate clicks as well.

Which gets to the heart of the matter: AVG's security philosophy is fundamentally at odds with webmaster peace of mind. The company wants to scan search results, and it wants to scan them in a way that's difficult to distinguish from real traffic. "In order to detect the really tricky - and by association, the most important - malicious content, we need to look just like a browser driven by a human being," AVG chief of research Roger Thompson has told us.

And if that causes problems for webmasters, Thompson says, so be it. "I don't want to sound flip about this, but if you want to make omelets, you have to break some eggs."

Clearly, the company doesn't fully realize the importance of web analytics. "Web analytics is about finding trends which can help online marketers/webmasters improve things for their visitors and their businesses," says Steve Jackson, co-chair of the International Web Analytics Association. "It's a big part of the whole online ecosystem in a fast growing up industry.

"No-one wants spyware or viruses, and AVG does provide a useful service which is getting better all the time. I wish, however, they would take business needs into account before launching software that makes life even more difficult for the people trying to do the analytics. Web analytics is not easy at the best of times, and this kind of thing from AVG just compounded the problem.

"In order to make an omelet you have to crack some eggs. But a good omelet has cheese, ham, peppers, mushrooms and all sorts of other ingredients which AVG seem to have forgotten about."

But AVG continues to say it's working to solve the problem - including the bandwidth issue. Referring to LinkScanner's new IE6-like user agent, Thompson told us, "We intend to leave those in place until we can find the right balance point which will allow us to continue to provide the best possible protection for our customers, without imposing too much extra bandwidth on websites."

AVG disguises fake traffic as IE6