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This article overviews configuration settings and some useful extensions which enhance security and privacy while using the Firefox web browser.

Configuration tweaks

The following are privacy-focused configuration tweaks to prevent browser fingerprinting and tracking.

In addition, see the following links:

  • How to stop Firefox from making automatic connections - Is an annotated list of corresponding Firefox functionality and settings to disable it case-by-case.
  • - You select which features you want to enable and disable and in the end you get a download link for a zip-file with your profile template. You can for example disable some functions, which send data to Mozilla and Google, or disable several annoying Firefox functions like Mozilla Hello or the Pocket integration.
  • pyllyukko/user.js - Firefox configuration hardening and documentation

Enable tracking protection

Firefox gained an option for tracking protection. It can be enabled by setting about:config:

  • privacy.trackingprotection.enabled true

Apart from privacy benefits, enabling tracking protection may also reduce load time by 44%.

Note that this is not a replacement for ad blocking extensions such as #uBlock Origin and it may or may not work with Firefox forks.

Change browser time zone

The time zone of your system can be used in browser fingerprinting. To set firefox's time zone to UTC launch it as:

$ TZ=UTC firefox

Or, set a script to launch the above (for example, at /usr/local/bin/firefox).

Change user agent and platform

You can override Firefox's user agent with the general.useragent.override preference in about:config.

The value for the key is your browser's user agent. Select a known common one.

Tip: The value Mozilla/5.0 (Windows NT 6.1; rv:52.0) Gecko/20100101 Firefox/52.0 is used as the user agent for the Tor browser, thus being very common.
Warning: Changing the user agent without changing to a corresponding platform will make your browser nearly unique.

To change the platform for firefox, add the following string key in about:config:


Select a known common platform that corresponds with your user agent.

Tip: The value Win32 is used as the platform for the Tor browser, corresponding with the user agent provided above.

WebRTC exposes LAN IP address

To prevent websites from getting your local IP address via WebRTC's peer-to-peer (and JavaScript), open about:config and set:

  • to true
  • media.peerconnection.enabled to false. (only if you want to completely disable WebRTC)

You can use this WebRTC test page and WebRTC IP Leak VPN / Tor IP Test to confirm that your internal/external IP address is no longer leaked.

Disable 1024-bit Diffie-Hellman primes

Following recent research it is likely that the NSA has been breaking 1024-bit Diffie-Hellman for some time now. To disable these switch the following settings to false in about:config:


Then consider checking your SSL configuration at

Disable telemetry

Set toolkit.telemetry.enabled to false and/or disable it under Preferences, Advanced, Data Choices.

Enable Do Not Track Header (DNT)

Note: The remote server may choose to not honour the Do Not Track request.

Set privacy.donottrackheader.enabled to true or toggle it in Preferences > Privacy > Manage your Do Not Track settings.

Disable geolocation

Set geo.enabled to false in about:config.

Disable Safe Browsing service

Safe Browsing offers phishing protection and malware checks, however it may send user information (e.g. URL, file hashes, etc.) to third parties like Google.

To disable the Safe Browsing service, in about:config set:

  • browser.safebrowsing.malware.enabled to false
  • browser.safebrowsing.phishing.enabled to false

In addition disable download checking, by setting browser.safebrowsing.downloads.enabled to false.

Disable WebGL

WebGL is a potential security risk.[1] Set webgl.disabled to true in about:config if you want to disable it.


HTTPS Everywhere

HTTPS Everywhere is an extension which encrypts your communication with a website. It forces a connection over HTTPS instead of HTTP wherever possible.

HTTPS Everywhere will be automatically configured and enabled upon restarting Firefox. For information on how to set up your own rules for different websites please visit the official website.

Note: HTTPS Everywhere does not magically enable HTTPS for every site on the internet. The site needs to support HTTPS and HTTPS Everywhere should have a ruleset configured for that site.

uBlock Origin

uBlock Origin is a lightweight, efficient blocker which is easy on memory and CPU. It comes with several filter lists ready to use out-of-the-box (including EasyList, Peter Lowe's, several malware filter lists).

The lead developer of uBlock forked the project and created uBlock Origin. As of July 2015, most of the development is being done on uBlock Origin and the codebases are deviating substantially.

uBlock Origin: Github; Firefox Add-ons.


AdNauseam is a lightweight browser extension that blends software tool and artware intervention to fight back against tracking by advertising networks. AdNauseam works like an ad-blocker (it is built atop uBlock-Origin) to silently simulate clicks on each blocked ad, confusing trackers as to one's real interests [2].

Adblock Plus

Adblock Plus was a popular extension to block ads. Now that it is not blocking some ads on purpose [3], it may be a better idea to use a different blocker like uBlock Origin.

Privacy Badger

Privacy Badger is an extension that monitors third-party trackers loaded with web content. It blocks trackers once they appear on different sites. It does not block advertisements in the first place, but since a lot of ads are served based on tracking information these are blocked as well. For more information on the mechanism, see its FAQ.


Disconnect is a open source project aimed at stopping 2,000 third-party sites from tracking a user. It encrypts data sent to popular sites and claims to loads web pages 27 percent faster. Disconnect shows its users, in real time, how many tracking attempts from Google, Twitter, Facebook, and more are stopped. It categorizes tracking attempts into advertising, analytical, social, and content, which makes it easy to monitor how one is being tracked.

Disconnect can also stop side-jacking, which utilizes stolen cookies to steal personal data. It is easy to use and well supported. It can be added to Firefox at the official website.

Note: Firefox gained a feature based on the Disconnect list. See #Enable tracking protection.


NoScript is an extension which disables JavaScript, Java, Flash and other plugins on any website not specifically whitelisted by the user. This extension will protect you from exploitation of security vulnerabilities by not letting anything but trusted sites (e.g: your bank, webmail) serve you executable content.

Once installed you can configure settings for NoScript by either clicking its icon on the toolbar or right clicking a page and navigating to NoScript. You will then have the option to enable/disable scripts for the current page, as well as any third party scripts that the page is linking to. Alternatively you can choose to enable scripts temporarily for that session only.

Be aware a lot of modern websites use scripts for layout purposes, hence content may look different. For example, failed rendering due to missing fonts might occur on websites that load fonts at runtime via scripts, which were blocked by NoScript.

For more detailed configuration see the NoScript FAQ.


uMatrix is forked and refactored from HTTP Switchboard. It allows you to selectively block Javascript, plugins or other resources and control third-party resources. It also features extensive privacy features like user-agent masquerading, referering blocking and so on. It effectively replaces NoScript and RequestPolicy. See the old HTTP Switchboard wiki for different ways how to use it.

For more Information visit the project site.

Cookie Monster

Cookie Monster is a similar extension to NoScript but will the goal of managing cookies.

From the preferences for Cookie Monster select "Block All Cookies". Once this is done, just as with NoScript, you can enable the use of cookies for specific pages from either the Cookie Monster icon on the toolbar or by right clicking the page and navigating to Cookie Monster. You have the option to accept cookies from the website in question or alternatively to only temporarily allow cookies for the current session.

Cookie AutoDelete

Cookie AutoDelete is an extension that deletes cookies as soon as the tab closes. Supports automatic and manual cookie cleaning modes. Clearing LocalStorage is not yet supported.


RefControl is an extension to control what gets sent as the HTTP Referer. Once installed RefControl can be configured so that no referer gets sent when navigating to a new webpage. This prevents the server from knowing which website you originated from.

To do this open RefControl's preferences and change the setting for "Default for sites not listed:" to <Block>.

Note: Firefox has options to control emitted HTTP referers, possibly replacing plugins such as RefControl and Smart Referer. See Firefox tweaks#Referrer header control.


RequestPolicy is an extension for Mozilla browsers which lets you have control over cross-site requests. The latest development version lets you blacklist or whitelist requests by default. Disabling unnecessary cross-site requests leads to better privacy, safety and faster browsing.

For more information on cross-site requests and RequestPolicy visit here.


Decentraleyes protects you against tracking through "free", centralized, content delivery. It prevents a lot of requests from reaching networks like Google Hosted Libraries, and serves local files to keep sites from breaking. Complements regular content blockers.


CanvasBlocker Blocks or fakes the JS-API for modifying <canvas> to prevent Canvas-Fingerprinting.</canvas>

Random User Agent

Random User Agent rotates complete browser profiles (from real browsers/devices) at a user defined time interval. It includes many extra privacy enhancing options.

Privacy Settings

Privacy Settings provides a toolbar panel for easily altering Firefox's built-in privacy settings.

Stop Fingerprinting

Stop Fingerprinting disables / modifies some browser APIs that would otherwise allow browser fingerprinting.