user.js | Firefox Fenix Nightly, Iceraven, Fennec F-Droid and Mull

The user.js file is used to configure Firefox for android in the safest and fastest way possible.

Goals:

• enhance security and privacy
• improve performance
• better fingerprint possible
• reduce automatic connections

Compatible browsers:

This user.js has been designed for mobile purposes and you can use it on these browsers:

• Firefox Fenix Nightly for Android - Mozilla-mobile
• Iceraven browser - Forks maintainers
• Fennec F-Droid - F-Droid
• Mull - F-Droid

If you are running IcecatMobile or old Fennec (version 68) use Quindecim user.js instead.

How to install:

ROOT METHOD 1 (file manager)

I would like to suggest the use of Amaze, Simple File Manager Pro, Material Files or TWRP File Manager before proceed.

• Download and install the browsers from their official websites (see above)

• Start the browser for the first time (offline mode/no data connections) and wait about 5 sec.

• Close it.

• Clone or download zip file and extract it

• Locate browser's installation directory similar to this:

  ✳️ Firefox Fenix Nightly data/data/org.mozilla.fenix/files/mozilla/[xxxxxxx].default

  ✳️ Iceraven data/data/io.github.forkmaintainers.iceraven/files/mozilla/[xxxxxxx].default

  ✳️ Fennec F-Droid data/data/org.mozilla.fennec_froid/files/mozilla/[xxxxxxx].default

  ✳️ Mull data/data/us.spotco.fennec_dos/files/mozilla/[xxxxxxx].default

• Copy the extracted user.js file to the above installation directory.

• Delete prefs.js file inside the above directory

• Start the browser and test if user.js was applied : browse to about:config (put it in search bar) and look if config.applied is true.

If this doesn't work I suggest you to use the ROOT METHOD 2 below.

ROOT METHOD 2 (app)

• Download and install the browser from their official websites.

• Download and install User.js Updater

• Start the browser for the first time (offline mode/no data connections) and wait about 5 sec.

• Close it.

• Open User.js Updater app and grant storage permission.

• Choose Custom and write the following:

  https://git.nixnet.services/Narsil/mobile_user.js/src/branch/master/user.js

• Tap UPDATE at the bottom and grant root permission.

• Start the browser and test if user.js was applied : browse to about:config (put it in search bar) and look if config.applied is true.

• AFWall+ USERS: You can disable Use Download Manager option into Settings and enable data connection just to the app itself.

Installing Iceraven addons in Fennec/Mull/Firefox Nightly

Go to Settings, about Fennec/Mull/Firefox Nightly, tap 5 times over its logo, Debug mode will enable. Back to Settings, the new Custom Add-on collection and add the Iceraven one: 16201230 What-I-want-on-Fenix

If you still need more of them you will have to create your own Collection: https://www.ghacks.net/2020/10/01/you-can-now-install-any-add-on-in-firefox-nightly-for-android-but-it-is-complicated/

Considerations

Once installed go to Settings, ETP and select Strict.

Some automatic connections could not be blocked so you will have to add them to your host list.

firefox.settings.services.mozilla.com

https://bugzilla.mozilla.org/show_bug.cgi?id=1598562#c13

content-signature-2.cdn.mozilla.net

safebrowsing.googleapis.com, safebrowsing.google.com, malware-error.mozilla.com, phish-error.mozilla.com and developers.google.com (safebrowsing is active and not changeable)

https://github.com/mozilla-mobile/fenix/issues/14163

Known problems

Some breakage?

Try changing "network.http.referer.XOriginPolicy" from 2 to 1

Performance loss?

Not active currently, maybe in the future. You have to change these strings from false to true:

javascript.options.ion

javascript.options.baselinejit

javascript.options.native_regexp

Bugs with HTTP sites?

Due to fission enabled loading HTTP websites when HTTPS only mode is enabled doesn't work. Consider disabling it. There are also issues with self signed certificates in HTTPS webs.

Thanks

I really thank the following authors:

• Arkenfox - The majority of this user.js.
• Tor Project - Some Tor Browser strings.
• Quindecim - Initial releases, unique strings and user design.
• LibreWolf - Some strings.
• Better-Fox - Some strings
• gallegonovato - For his suggestions and support.
• v1nc - For his user.js updater app.

License

GNU General Public License v3.0.

See LICENSE for more details.

Other mirrors

https://codeberg.org/Narsil/user.js/src/branch/main/mobile