'HTTP_REFERER' -- Is this concealed by privacy software?

[JerryHobby]

Greetings all,

I have a customer who complains his 'HTTP_REFERER' stats are not accurate. He is basing this on Urchin reports. Urchin shows a large percentage of visitors NOT having not been referred, however he expects that nearly all of his visitors are referred from other sites.

As I see it, there are two possibilities. One is that Urchin is getting bad data somehow from the logs. The other is that 'HTTP_REFERER' data is not being collected by Apache for some reason. Assuming the later, my theory is that modern antivirus / privacy software may be blocking Apache from learning the source of the referral.

I have work arounds for gathering stats by using GET parms for all inbound links, however that is a lot of trouble and doesn't integrate with Urchin, etc.

Does anyone have some insights or suggestions on the best way to collect reliable referral stats? Have any of you noticed the particular problem?

Thanks!
Jerry

[someonewhois]

Things like Norton Security block referrer addresses, though I don't think tha twould result in a very large discrepency (depends on the market though).

[Thermit]

Hey Jerry.

I get tons of "-" no ref entries in my logs, and I suspect that they aren't all bookmarks and type-ins as well.

I know that some programs will hide the referrer value by replacing them with a message instead, like "blocked by outpost" or "wouldn 't you like to know?".

Since this field is totally spoofable, it seems to just come with the territory...

[vinyl-junkie]

Since this field is totally spoofable, it seems to just come with the territory...

To expand further on this statement, here's a quote from the PHP manual that should apply no matter what was used to make a web page:

['HTTP_REFERER' is] The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this, and some provide the ability to modify HTTP_REFERER as a feature. In short, it cannot really be trusted.