A Firefox hardening quick guide

 DEPRECATED: Instructions valid until 2020. A lot has changed since then. 

The results of this guidelines render only a casual-use Firefox configuration. If you have special privacy/anonimity needs, or are concerned about sofisticated attack vectors, then please do not use Firefox (Or use it with other privacy-enhancing services/softwares). Do your own modifications and research as needed.

The purpose of this setup is for Privacy and protection against tracking/fingerprinting and malicious sites. Not Anonimity.

Firefox profiles

Firefox profile manager:

Windows: Win+R -> “firefox.exe -P”

Linux: In terminal -> “firefox -P”


  • (Windows) C:\Users<username>\AppData\Roaming\Mozilla\Firefox\Profiles<profile_name>
  • (Linux) /home/<username>/

Custom, security-focused, automatic profiles (Worth to check out):

User.js (https://github.com/arkenfox/user.js).

Download user.js file & modify as needed. Examples:

- *user_pref("intl.accept_languages", "en-US, en");*
- *user_pref("app.update.auto", true);*

Save file in a new profiling location > Open profile manager > Create new profile and add the recently created folder.

Firefox Profilemaker (https://ffprofile.com)

Guidance provided at “start” click.

Download profile. Apply to a new profile.

Manual Configuration

About:preferences Common privacy/security preferences:

  • OCSP enabled
  • Enable DNT (Do Not Track)
  • Disable cookies/Fingerprinting
  • Manage cookie storage (As needed)
  • Block dangerous content
  • SOCKSv5 / HTTP proxy if needed.
  • Enable DoH (DNS over HTTPS); select a secure DNS server. (Needs more testing)


  • (TLS minimum version) “security.tls.version.min” -> 3,

  • (See the full URL @ search bar) browser.urlbar.trimURLs -> true

  • (Randomize http referer) network.http.referer.spoofSource -> true

  • (Disable fonts) browser.display.use_document_fonts -> 0

  • (Auto-update Firefox) extensions.update.autoUpdateDefault -> true/false

  • (Fingerprinting) privacy.resistFingerprinting -> true

  • See saved Certificate Authorities (CA): about:certificate

Addons & Extensions

  • Certificate patrol (Current Cas)
  • EFF’s Privacy Badger
  • Cookie quick manager
  • Privacy Settings / Ublock Origin / uMatrix (Advanced)
  • User-Agent Switcher (Check for the most common user-agent headers)
  • CanvasBlocker

Browsers to use

Tools for testing your browser’s fingerprint, headers, DNS leaks, etc.

Other readings

CIS official benchmark

Sources: StationX, Electronic Frontier Foundation (EFF), Mozilla Foundation, JonDonym.

Written By


Cybersecurity professional and IT enthusiast with a passion for technology, music, personal growth, and Eastern philosophy. Transitioned from mechanical engineering to IT in 2020, with a full-time interest in Technology, Cybersecurity and recent advances in AI. Seeks to integrate eastern philosophy, mindfulness and a growth mindset into daily life and work.