> What I do is calling a Perl script in the same way as you do. It > sanitizes > my data (browser goes into browser file, referrer goes into referrer file > etc) and then sends a transparent image back to the browser. That's good and even vital if you're using the same webserver for all your http traffic, in my project I have a web server devoted to login traffic for this CGI script, because there will be a lot of requests from different sites. The log files will be huge, but hopefully there will be one line for each request. The thing I am a bit stuck on is how to avoid people cheating, that's why I am logging the top.location, document.referrer as well as the referrer that gets logged along a standard http request. But the checking will be in the batch processing of the logfiles, probably matching the 3 infos with a list of valid domains.. I don't know exactly.. > If you wish I can send you a Perl browser detect module I wrote. > The coding > is not too good, but it's up to date (Omniweb is the last browser added). That would be helpful, althought I am not working on this part yet and it might be somebody else working on it later.. Thank you and have a nice day.