The webserver logs showed I was being followed on my path through a website by a computer at an IP address in Texas. It trailed two seconds behind me, on every page.
It was a dark and stormy day, and a strange thing happened while I was debugging some PHP code.
I was using error_log to pass some variables and values to the standard Apache log, and tailing it to make sure PHP was seeing what I wanted it to see. That was when I saw something I didn’t expect to see.
[Thu Jun 09 13:37:54 2011] [error] [client 24.xxx.xx.xxx] Carrier: ... [Thu Jun 09 13:37:54 2011] [error] [client 24.xxx.xx.xxx] Returning ... [Thu Jun 09 13:37:56 2011] [error] [client 75.xxx.xx.xxx] Carrier: ... [Thu Jun 09 13:37:56 2011] [error] [client 75.xxx.xx.xxx] Returning ...
Each time I hit the page, my code logged the access. Then, a second or two later, another entry from a different IP address was also logged.
Everything I did was being shadowed by a server in Texas.
It took a few minutes of research to discover that the IP address belongs to one of ClickTale’s servers, and that the page I was modifying runs their analytic code. Freakiness abated.