[thelist] HTTP_REFERER v user agent

[Andrew Clover]

> This is a bit worrying. Does anyone know which user agents (eg browsers) 
> prevent this?

None I know of allow it to be altered, but at least Opera and 
Mozilla-with-extensions allow it not to be sent at all. Some security- 
or performance-related web proxy apps allow it to be blocked or altered 
independently of the browser.

 > I need to ensure that all visitors orgins are known: ie which ads
 > they have come in on.

You don't and you can't. You cannot rely on anything the user agent 
passes you as being 100% accurate. You *can* try and judge your stats 
with this in mind and still detect useful trends and information.

> Maybe the only way to do this, rather than putting code into the entry 
> page, is to rely on the access logs?

The access logs provide you the same information a PHP script can 
access; a referrer field will appear the same to both.

-- 
Andrew Clover
mailto:and at doxdesk.com
http://www.doxdesk.com/