Tor Browser Customization using user.js (for example for i2pbrowser)

I was wondering if creating user.js:


Some settings such as:

user_pref("network.proxy.socks_remote_dns", false);

can be changed. Result:

No. Unfortunately above cannot be changed. It seems it is now hardocded in a binary file: /home/user/.tb/tor-browser/Browser/

To make sure my method is valid of using user.js is right, that the file path to user.js is correct, that user.js is generally supported. Yes. Generally using user.js method is still functional. For example the following setting could be changed for testing purposes:

user_pref("", "test");

Just some settings are hardcoded now in Tor Browser and I am not aware of any persistent way to change them.

All settings can still be changed in about:config but some settings - those hardcoded by Tor Browser - will be reverted after Tor Browser restart.

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Using prefs.js didn’t help either.


Settings in prefs.js such as user_pref("network.proxy.socks_remote_dns", false); are not honored (omitted) and even prefs.js is reset after browser start. I.e. the custom setting is removed.

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If you were to maintain 2 copies of the Tor Browser, then you could configure it in policies.json instead, which might yield different results. I’ve only done a little testing on my end to experiment with in-I2P TLS certificates, but so far this mechanism has allowed me to configure some things in Firefox which I could not before.

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As per currently

  • /etc/firefox/policies/policies.json works, but in the future it might become
  • /etc/firefox-esr/policies/policies.json