Tails' Tor Browser User Agent String Should Match Standalone Tor Browser's

The User Agent String for Tails’ Tor Browser is very unique. While I am thankful for

“privacy.resistFingerprinting.spoofOsInUserAgentHeader”

toggle in about:config, where I can toggle between Linux/Windows there still remains unique characters in the string, that being the FF version number. Aside from a few websites refusing my traffic on the grounds the web browser version is too old, the current string stands out and in the interest of privacy (and common sense) it should match the standalone Tor Browser’s current User Agent String.

It has been preached for years not to change the user agent. Well, the default in Tails is different and should match standalone Tor Browser’s string.

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I did not know this but it is hard to disagree.

Those sites which refuse your traffic could be doing it just because you are using Tor. Many sites block Tor because of people’s abuse.

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@clown - what is the default value of the pref in Tail’s Tor Browser?

It should be default false and you shouldn’t be changing it as it alters your fingerprint. It was supposed to be removed (and was only a stop gap measure during the change). Besides the fact that it clearly alters your fingerprint, since it was dropped (spoofing HTTP header as windows in linux and mac), the windows spoof (on windows) was also changed

edit: Remove privacy.resistFingerprinting.spoofOsInUserAgentHeader machinery entirely (#43189) · Issues · The Tor Project / Applications / Tor Browser · GitLab

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The pref is false in stable, and the code remains

The code has been ripped out in alpha and is slated for Tor Browser 14.5. The pref currently exists but will also be removed, as it no longer does anything

14.5 is due out soon


The version number is the same for all TB users and is not unique, and it is not too old (except for asshole websites) as it is based on the ESR cycle. The version number is in fact zero entropy within the “crowd” of TB users. And the userAgent entropy is equivalency of OS (linux, mac, android, windows: which you can’t hide even with no JS)


That just leaves your claim that Tails and TB-on-linux have different userAgent strings which I find hard to believe, unless you fiddled with about:pref

The HTTP Header for userAgent should be identical in TB on linux, and Tor Browser on Tails - at default false, and even at true

FYI @PieroV

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The default user agent in Tails Linux is:

Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0

When I toggle it in about:config it is:

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:128.0) Gecko/20100101 Firefox/128.0

I’ll admit it’s been awhile since I’ve looked at the user agent string in standalone Tor but this just struck me as different.

Hi and thanks. 99% of the blocked sites don’t mention my browser’s FF #. In 1%, which was just a few, specifically mentioned the browser version as unsupported and recommended an update.

It’s been some time since I checked the UAS in both standalone TB for Windows and Linux versions. Excuse me if I’m incorrect, but IIRC the Linux version was given the Windows version UAS so they would be identical. If this has changed, then my bad and thank you. I was unaware that the standalone TB for Linux identified itself as Linux rather than Windows, if that is policy now. I would think the UAS being the same across standalone TB platforms and Tails’ TB would make more sense.

You said it – asshole websites! :rofl:

Ah ha! This is the details I’ve been looking for. Thank you so much for mentioning this and linking to the issue on gitlab! I’ll mark this as solved thanks to you once my posts here are approved! :star_struck:

A thought came to me. Why don’t both claim to be the latest version of Google chrome running on the latest version of Windows. Each has about 80+ of the market. You could then melt in with the crowd. How can that NOT be more normal. FF version 128 is a bit old and a dead giveaway but then your IP would still give you away.

Maybe that would illegal. Who knows. If so, then an option which you can turn on and they are off the hook.

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claim to be the latest version of Google chrome

you can’t hide the browser engine (there are 10’s of thousands of differences that are trivial and extremely quick to detect), and spoofing the userAgent would just create compat issues

when you protect a fingerprinting metric and you need to lie about it, it is always best to be plausible

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