How to stop Tor browsers from forging the user agent string?

Question

The Tor browser is useful when you want to read regionally restricted websites, for example.

Unfortunately, the Tor Browser also changes the browser agent string, so that some websites that check it for plausibility refuse to display the website because of the fake user agent string.

The fact that some websites can also deny the Tor Browser on the basis of the IP address used by the Tor Browser is known and explicitly not meant in this question.

Example for fake user agent string of the Tor Browser:

Mozilla/5.0 (Windows NT 10.0; rv:102.0) Gecko/20100101 Firefox/102.0

The not faked one should be about p.e. the follow:

Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0

The Browser-Agent string can checked on webpages like:

• https://browserleaks.com/ip

How can I disable the named current Tor browser from faking the user agent string?

Answer 1

You can't: this is what they built this program for - to mimic for the mass. The goal of this approach is to blend into the most ubiquitous software and to make fingerprinting/identification a way more laborious. When the fingerprinting occurs - it tries every way to inject some tokens, so that's why these mimics and tweaks are hardcoded into the binary - there's no another way! Keep in mind that Tor provides SOCKS5s and HTTPS proxy endpoints, so you can use any software supporting them - including the browser you need. If you're afraid of hacks - just use unrouted virtual machine in VirtualBox as a disposable sandbox!

Answer 2

Currently, the TOR browser does not spoof your user agent and therefore you cannot ask it to just forward the message without forging a user agent. You can determine what the user agent will be as explained here, but it's not possible to have the TOR browser use your ideal user agent without setting it manually.

On another note you should probably let the TOR browser use its default user agent as customizing it would make your messages less anonymous, but it's up to you.

Of course most of the people would have an incredibly tough time trying to trace your messages, but remember that TOR is being used to provide privacy also from huge budget organizations like governments, and reducing your anonymity slightly could have a massive outcome with their resources.

From the TOR Blog (this is the default approach):

In the end, the approach chosen by Tor developers is simple: all Tor users should have the exact same fingerprint. No matter what device or operating system you are using, your browser fingerprint should be the same as any device running Tor Browser (more details can be found in the Tor design document).