After a discussion with a friend a few days ago, who claimed that google was tracking every click on its search result pages, I took a closer look.

Try the following:

• Search for something in google. (e.g. blogmal)
• Hover over a search result (do not click), and look at the URL in the statusbar.
• Click (and hold) your (left) mousebutton, and watch the statusbar.

It turns out, Google returns its links in the form:

<a href="http://www.42.org/~sec/blogmal/"
onmousedown="return rwt(this,'res','2','')">

where the rwt() function is defined in the header of that page:

function rwt(el,ct,cd,sg){
  el.href="/url?sa=t" +
	"&ct="+escape(ct)+
	"&cd="+escape(cd)+
	"&url="+escape(el.href).replace(/\+/g,"%2B")+
	"&ei=eDMcQ5uFIcHiiALL4pzuDg"+ sg;
 el.onmousedown="";
 return true;
}

They redefine the URL on click in an ugly attempt to hide what they are doing.

If you want to get an idea know how many of your links google already tracked, enter www.google.com/url in your (firefox) address bar, and wait for the autocompletion menu to show up.

Well. Time to look into greasemonkey, I've got to turn this off.

EDIT: The needed greasemonkey user script is here. Click on that link, then select Tools|Install this user script. (thanks to Nick)

– Sec

Note: If you use a localized google version (e.g www.google.de ) use that one instead of .com to check.