0

I've just configured Tor Browser Bundle as a normal browser (that is directing the traffic over the normal internet route rather than the Tor network) by following these (and these) instructions. This is just for some measurements I need to do, and I am not going to use this for normal browsing so anonymity is not a concern over here.

So, basically, what I want to do is to measure the page load time of a website loaded on this modified Tor browser. I was using this add-on in Firefox (52.0.2) previously but it ceases to work in Tor. I was wondering, are there any configurations (for example in about:config) that Tor has that prevent this add-on from working?

1

Yes, Tor Browser disables a lot of performance timing options since they can be used in side-channel and fingerprinting attacks from javascript on webpages.

The extension code does this

function reportTiming() {
  self.port.emit('timing', JSON.stringify(performance.timing));
}
window.addEventListener('load', function() {
  if (performance && performance.timing) {
    reportTiming();
  }
}, false);
if (performance && performance.timing && performance.timing.loadEventEnd > 0) {
  reportTiming();
}

But since performance.timing.loadEventEnd > 0 will never be true, it'll never report the page load end timing and so won't get a diff to measure from.

There are a few about:config setting you may want to look at: dom.enable_user_timing, dom.enable_resource_timing and dom.enable_performance.

  • Thanks for your response! I looked into these and just set them as true but that doesn't seem to have any effect for some reason. – QPTR Apr 8 '17 at 7:05
  • Strange, it works for me. Enabled those 3 settings and reloaded the page with the addon installed and it gave me results? – cacahuatl Apr 8 '17 at 16:39
  • It works now. I think the problem was that dom.enable_performance parameter seems to reset itself when I close the browser. It works when I enable it again. Any ideas on why it resets? – QPTR Apr 8 '17 at 17:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.