Hello!

Nowshin, Nafisa:

Hello,

I am a graduate student at Oregon State University doing research on digital privacy and security. My advisor is Dr. Glencora Borradaile. We are trying to use tor metrics data in order to understand the reason why people are connecting to tor and if it is because of some external motivation (the topic of our research) or because they are regular users. Looking at the user statistics available in tor metrics website, we had a few questions we wanted to clarify.

1. How frequently tor browsers send out update pings? Is there a fixed

frequency or do they vary over time? 2. Are update pings sent every time a user opens their browser or only when new updates are pushed to the tor browser?

To answer both questions at once, there are two mechanisms at play here:

1. Update pings are sent whenever the user opens their browser. You can see that for yourself in the browser console (Ctrl + Shift + J) after setting `extensions.torbutton.loglevel` to `3` on `about:config` and restarting Tor Browser. The requests to look for are those to

https://aus1.torproject.org/torbrowser/update_3/release

which is where our updates are hosted.

2. If you have Tor Browser open for a long time you won't hit the condition under 1. Thus, there is a second mechanism available governed by the `app.update.interval` preference, which is set to 43200 seconds on the stable channel and 7200 seconds on the other ones and firing accordingly.

Hope this helps.

Thank you for your time.

No worries and you are welcome. Let us know if there are other questions/things we can help with.

Georg

Regards

Nafisa Nowshin Graduate Assistant School of EECS, Oregon State University

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