Chapter 20. Configure Firefox
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Chapter 20. Configure Firefox

  1. Make Firefox the default

    If necessary: sudo update-alternatives --set gnome-www-browser /usr/bin/firefox

  2. Set Firefox interface font

    Firefox may be using the GTK3 system font, so consider trying that. Firefox will also use userChrome.css, so that's the most reliable way. mkdir -p ~/.config/mozilla/firefox/blahblah.default/chrome cp ~/Dropbox/Basic/new_machine/linux/firefox/userChrome.css ~/.config/mozilla/firefox/blahblah.default/chrome

    Note that this will have no effect unless toolkit.legacyUserProfileCustomizations.stylesheets is enabled. This is done by the user.js preference file in the next step.

  3. Configuration

    Copy preference file to profile. cp ~/Dropbox/Basic/new_machine/linux/firefox/user.js ~/.config/mozilla/firefox/PROFILE_DIR/

    Note

    ~/.config/mozilla/firefox/PROFILE_DIR/user.js source:

    // Mozilla User Preferences

// user.js overrides

user_pref("app.update.auto", false);
user_pref("app.update.suppressPrompts", true);
user_pref("browser.aboutConfig.showWarning", false);
user_pref("browser.ai.control.default", "blocked");
user_pref("browser.ai.control.linkPreviewKeyPoints", "blocked");
user_pref("browser.ai.control.pdfjsAltText", "blocked");
user_pref("browser.ai.control.sidebarChatbot", "blocked");
user_pref("browser.ai.control.smartTabGroups", "blocked");
user_pref("browser.ai.control.smartWindow", "blocked");
user_pref("browser.ai.control.translations", "blocked");
user_pref("browser.bookmarks.addedImportButton", false);
user_pref("browser.bookmarks.addedImportButton", false);
user_pref("browser.bookmarks.restore_default_bookmarks", false);
user_pref("browser.enable_automatic_image_resizing", false);
user_pref("browser.link.open_newwindow.restriction", 0);
user_pref("browser.ml.chat.enabled", false);
user_pref("browser.ml.chat.hideLocalhost", false);
user_pref("browser.ml.chat.menu", false);
user_pref("browser.ml.chat.page", false);
user_pref("browser.ml.chat.page.footerBadge", false);
user_pref("browser.ml.chat.page.menuBadge", false);
user_pref("browser.ml.chat.sidebar", false);
user_pref("browser.ml.enable", false);
user_pref("browser.ml.linkPreview.enabled", false);
user_pref("browser.newtabpage.activity-stream.asrouter.userprefs.cfr.addons", false);
user_pref("browser.newtabpage.activity-stream.asrouter.userprefs.cfr.features", false);
user_pref("browser.newtabpage.enabled", false);
user_pref("browser.search.context.loadInBackground", true);
user_pref("browser.settings-redesign.promo.dismissed", true);
user_pref("browser.smartwindow.memories.generateFromConversation", false);
user_pref("browser.smartwindow.memories.generateFromHistory", false);
user_pref("browser.startup.homepage", "chrome://browser/content/blanktab.html");
user_pref("browser.startup.page", 3);
user_pref("browser.tabs.dragDrop.createGroup.enabled", false);
user_pref("browser.tabs.groups.smart.enabled", false);
user_pref("browser.tabs.groups.smart.userEnabled", false);
user_pref("browser.termsofuse.prefMigrationCheck", true);
user_pref("browser.toolbarbuttons.introduced.sidebar-button", true);
user_pref("browser.translations.enable", false);
user_pref("browser.uiCustomization.state", "{\"placements\":{\"widget-overflow-fixed-list\":[],\"unified-extensions-area\":[],\"nav-bar\":[\"sidebar-button\",\"back-button\",\"forward-button\",\"stop-reload-button\",\"customizableui-special-spring1\",\"vertical-spacer\",\"urlbar-container\",\"customizableui-special-spring2\",\"downloads-button\",\"fxa-toolbar-menu-button\",\"unified-extensions-button\"],\"toolbar-menubar\":[\"menubar-items\"],\"TabsToolbar\":[\"firefox-view-button\",\"tabbrowser-tabs\",\"new-tab-button\",\"alltabs-button\"],\"vertical-tabs\":[],\"PersonalToolbar\":[\"import-button\",\"personal-bookmarks\"]},\"seen\":[\"developer-button\",\"screenshot-button\"],\"dirtyAreaCache\":[\"nav-bar\",\"vertical-tabs\",\"PersonalToolbar\",\"toolbar-menubar\",\"TabsToolbar\"],\"currentVersion\":23,\"newElementCount\":2}");
user_pref("browser.urlbar.placeholderName", "DuckDuckGo");
user_pref("browser.urlbar.placeholderName.private", "DuckDuckGo");
user_pref("browser.urlbar.shortcuts.actions", false);
user_pref("browser.urlbar.shortcuts.bookmarks", false);
user_pref("browser.urlbar.shortcuts.history", false);
user_pref("browser.urlbar.shortcuts.tabs", false);
user_pref("browser.urlbar.showSearchTerms.enabled", false);
user_pref("browser.urlbar.suggest.engines", false);
user_pref("browser.urlbar.suggest.history", false);
user_pref("browser.urlbar.suggest.quickactions", false);
user_pref("browser.urlbar.suggest.quicksuggest.all", false);
user_pref("browser.urlbar.suggest.searches", false);
user_pref("browser.urlbar.suggest.topsites", false);
user_pref("datareporting.healthreport.uploadEnabled", false);
user_pref("datareporting.usage.uploadEnabled", false);
user_pref("dom.webnotifications.enabled", false);
user_pref("extensions.formautofill.creditCards.enabled", false);
user_pref("extensions.ml.enabled", false);
user_pref("layout.spellcheckDefault", 0);
user_pref("network.dns.disablePrefetch", true);
user_pref("network.http.speculative-parallel-limit", 0);
user_pref("network.prefetch-next", false);
user_pref("nimbus.rollouts.enabled", false);
user_pref("pdfjs.enableAltText", false);
user_pref("privacy.globalprivacycontrol.enabled", true);
user_pref("privacy.globalprivacycontrol.was_ever_enabled", true);
user_pref("telemetry.fog.init_on_shutdown", false);
user_pref("trailhead.firstrun.didSeeAboutWelcome", true);

  4. Sync

    Set up Firefox sync.

  5. Reclaim the home page

    Changing new windows and tabs to use a blank page, and, just in case, turning off the privacy-compromising settings in Firefox Home Content. TODO: try to get all of these settings into user.js

  6. Go through config and disable all of the bad settings, including (as of 2025-09):

    1. Use AI to suggest tabs and a name for tab groups OFF

    2. Play DRM-controlled content OFF

    3. ¿Enable link previews?

    4. For Search, change engine to DuckDuckGo, disable suggestions, turn off most of Firefox Suggest, disable the worst search engines

    5. In Privacy & Security, turn off Send Technical and interaction data to Mozilla and related. Make sure Allow websites to perform privacy-preserving ad measurement is OFF.

  7. Note that Firefox tends to spam syslog, so we installed auditd along with the other debian packages; it segregates all apparmor messages and calms down the logs.

  8. Install Extensions

    Extensions may come over automatically from sync, but this is inconsistent. If necessary, load them manually: Ctrl+Shift+A

    • UBlock Origin

    • Unhook (youtube comments)

    • Noscript

    • Firefox Multi-Account Containers

    • Tree Style Tab (laptop only)

  9. TODOs for Firefox