Firefox: Privacy Related "about:config" Tweaks

Preparation:

  1. Enter "about:config" in the firefox address bar and press enter.
  2. Press the button "I'll be careful, I promise!"
  3. Follow the instructions below...

Getting started:

privacy.firstparty.isolate = true
A result of the Tor Uplift effort, this preference isolates all browser identifier sources (e.g. cookies) to the first party domain, with the goal of preventing tracking across different domains. (Don't do this if you are using the Firefox Addon "Cookie AutoDelete" with Firefox v58 or below.)
privacy.resistFingerprinting = true
A result of the Tor Uplift effort, this preference makes Firefox more resistant to browser fingerprinting.
privacy.trackingprotection.enabled = true
This is Mozilla's new built-in tracking protection. It uses Disconnect.me filter list, which is redundant if you are already using uBlock Origin 3rd party filters, therefore you should set it to false if you are using the add-on functionalities.
browser.cache.offline.enable = false
Disables offline cache.
browser.safebrowsing.malware.enabled = false
Disable Google Safe Browsing malware checks. Security risk, but privacy improvement.
browser.safebrowsing.phishing.enabled = false
Disable Google Safe Browsing and phishing protection. Security risk, but privacy improvement.
browser.send_pings = false
The attribute would be useful for letting websites track visitors' clicks.
browser.sessionstore.max_tabs_undo = 0
Even with Firefox set to not remember history, your closed tabs are stored temporarily at Menu -> History -> Recently Closed Tabs.
browser.urlbar.speculativeConnect.enabled = false
Disable preloading of autocomplete URLs. Firefox preloads URLs that autocomplete when a user types into the address bar, which is a concern if URLs are suggested that the user does not want to connect to. Source
dom.battery.enabled = false
Website owners can track the battery status of your device. Source
dom.event.clipboardevents.enabled = false
Disable that websites can get notifications if you copy, paste, or cut something from a web page, and it lets them know which part of the page had been selected.
geo.enabled = false
Disables geolocation.
media.eme.enabled = false

Disables playback of DRM-controlled HTML5 content, which, if enabled, automatically downloads the Widevine Content Decryption Module provided by Google Inc. Details

DRM-controlled content that requires the Adobe Flash or Microsoft Silverlight NPAPI plugins will still play, if installed and enabled in Firefox.

media.gmp-widevinecdm.enabled = false
Disables the Widevine Content Decryption Module provided by Google Inc., used for the playback of DRM-controlled HTML5 content. Details
media.navigator.enabled = false
Websites can track the microphone and camera status of your device.
network.cookie.cookieBehavior = 1
Disable cookies
network.cookie.lifetimePolicy = 2
cookies are deleted at the end of the session
network.http.referer.trimmingPolicy = 2
Send only the scheme, host, and port in the Referer header
network.http.referer.XOriginPolicy = 2
Only send Referer header when the full hostnames match. (Note: if you notice significant breakage, you might try 1 combined with an XOriginTrimmingPolicy tweak below.) Source
network.http.referer.XOriginTrimmingPolicy = 2
When sending Referer across origins, only send scheme, host, and port in the Referer header of cross-origin requests. Source
webgl.disabled = true
WebGL is a potential security risk. Source
browser.sessionstore.privacy_level = 2
This preference controls when to store extra information about a session: contents of forms, scrollbar positions, cookies, and POST data. Details
network.IDN_show_punycode = true
Not rendering IDNs as their Punycode equivalent leaves you open to phishing attacks that can be very difficult to notice. Source
extensions.blocklist.url = https://blocklists.settings.services.mozilla.com/v1/blocklist/3/%20/%20/

Limit the amount of identifiable information sent when requesting the Mozilla harmful extension blocklist.

Optionally, the blocklist can be disabled entirely by setting extensions.blocklist.enabled to false for increased privacy, but decreased security. Source

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