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Making Firefox private – “about:config” tweaks

Firefox: Privacy Related “about:config” Tweaks


  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:

  1. 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.)
  2. privacy.resistFingerprinting = true
    • A result of the Tor Uplift effort, this preference makes Firefox more resistant to browser fingerprinting.
  3. 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.
  4. browser.cache.offline.enable = false
    • Disables offline cache.
  5. browser.safebrowsing.malware.enabled = false
    • Disable Google Safe Browsing malware checks. Security risk, but privacy improvement.
  6. browser.safebrowsing.phishing.enabled = false
    • Disable Google Safe Browsing and phishing protection. Security risk, but privacy improvement.
  7. browser.send_pings = false
    • The attribute would be useful for letting websites track visitors’ clicks.
  8. 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.
  9. 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
  10. dom.battery.enabled = false
    • Website owners can track the battery status of your device. Source
  11. 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.
  12. geo.enabled = false
    • Disables geolocation.
  13. media.navigator.enabled = false
    • Websites can track the microphone and camera status of your device.
  14. network.cookie.cookieBehavior = 1
    • Disable cookies
    • 0 = Accept all cookies by default
    • 1 = Only accept from the originating site (block third party cookies)
    • 2 = Block all cookies by default
  15. network.cookie.lifetimePolicy = 2
    • cookies are deleted at the end of the session
    • 0 = Accept cookies normally
    • 1 = Prompt for each cookie
    • 2 = Accept for current session only
    • 3 = Accept for N days
  16. network.http.referer.trimmingPolicy = 2
    • Send only the scheme, host, and port in the Referer header
    • 0 = Send the full URL in the Referer header
    • 1 = Send the URL without its query string in the Referer header
    • 2 = Send only the scheme, host, and port in the Referer header
  17. 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 XOriginTrimmingPolicytweak below.) Source
    • 0 = Send Referer in all cases
    • 1 = Send Referer to same eTLD sites
    • 2 = Send Referer only when the full hostnames match
  18. 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
    • 0 = Send full url in Referer
    • 1 = Send url without query string in Referer
    • 2 = Only send scheme, host, and port in Referer
  19. webgl.disabled = true
    • WebGL is a potential security risk. Source
  20. 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. more information
    • 0 = Store extra session data for any site. (Default starting with Firefox 4.)
    • 1 = Store extra session data for unencrypted (non-HTTPS) sites only. (Default before Firefox 4.)
    • 2 = Never store extra session data.
  21. 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.
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