The Firefox Privacy Guide For Dummies!

Facebook created same day Pentagon kills similar project

See the revision history at the end (if you make it that far).

Before embarking on this journey into the bowels of Firefox, you may want to first read, Tor verses a VPN – Which is right for you?. If you choose to use the Tor Browser, you need not digest this guide.

You're aware that companies like Facebook, Google, YouTube and even your ISP are spying on you, even if you may not be aware of how they're doing it. You're concerned about this invasion of privacy, but aren't sure how to address the problem.

Welcome to the 'for dummies' edition of the Firefox Configuration Guide for Privacy Freaks and Performance Buffs!!!

Some of us aren't basement dwelling tech geeks yearning to fiddle around with gobs of obscure web browser settings. It is especially for you that The Firefox Privacy Guide For Dummies! was created.

The goal here is to provide a simple guide (to the extent that's possible) which will yield a privacy enhanced configuration of the Firefox web browser whilst breaking as few websites as possible. That said, be prepared to put a little more effort into your surfing activities, at least until the jello gels. The pay-off will be a much faster, cleaner web that is less able to track and profile you. Note i said "less", not "not".

WARNING: This guide is not for use with the Tor browser. Configuring the Tor browser as outlined in this guide will result in potentially serious risks to your privacy.

Catching the Fox

This guide isn't going to work spectacularly for any web browser other than Firefox and it's the standard release version you want, so if you don't have it, get it (if you run a Linux-based operating system, look in your package manager). Since it's privacy we're interested in we're way too smart to be goofing around with Google Chrome or Microsoft Edge, though if you have an inferior alternative browser installed you could certainly retain it as a backup.

Profiling the Fox

Once Firefox is installed, run it. After the little bugger calms down, enter about:profiles in the address bar (you can call it the "location" bar or the "awesome" bar – i call it the "address bar"), then press your 'Enter' key to load that address. This is where Firefox keeps a list of all your profiles. Profiles are where most of your settings, bookmarks and lots more junk gets stored.

Firefox Profile Manager
click me

You can have as many profiles as you want, but by default there will be just one named 'default'. We need more, so click the 'Create a New Profile' button and name the new profile 'privacy'. You can change the name later, but leave it be for now.

Firefox will now annoy you (and let it keep annoying you for the duration of our time together) by asking which profile you want to load every time you start it and you should typically choose your 'privacy' profile.

Pro Tip

There are many 'about:' pages in Firefox, but not all are accessible from the various menus. To see some of those that aren't, enter about:about in the address bar, but be careful what you do in there!

Training the Fox

Firefox Profile Manager 2
click me

If you've started Firefox with your new 'privacy' profile, you've already done a bad thing. It's OK, we're still on (reasonably) good terms, but don't test me like that again. Now we have to fix the mess you've made, so restart Firefox and when you see the window used to choose which profile you want to load, delete your privacy profile and all the files in it when you are prompted, then create a new privacy profile from about:profiles.

Firefox Pro Tip

If you don't want Firefox whining about which profile to load every time it starts, you can select your preferred profile and check the 'Don't ask at startup' option, but don't do that yet either! Another way is to create a shortcut to load any profile you want.

For more about profiles, see Use the Profile Manager to create and remove Firefox profiles and Multiple Firefox profiles.

For more about penguins being tickled, go here.


If you're running Windows you will need to unhide file extensions, and i suggest you keep them unhidden.

Start Firefox and load your 'default' profile, then either load about:preferences in the address bar or click Hamburg icon on the toolbar, then 'Preferences'. Click the 'Search' menu item on the left and then under where it says 'Search Bar', click 'Add search bar in toolbar'.

Next go to the ghacks-user.js GitHub repository. We need their prefsCleaner.bat (Windows) or (Linux) file and the updater.bat (Windows) or (Linux) file. Now before you mess up, hear me out: Click on the file names in the repository, then click the 'Raw' button, then press Ctrl+S to save the files to your desktop. Failing to heed my advice may cause Russia to interfere in the next election like they didn't in the last one. Now if you're one of those smart-asses who knows something about something, you may already know we're going to need that user.js file too but we'll grab that another way later on.

Next, go to the labwrat/Firefox-user.js GitLab repository and download the user-overrides.js file to your desktop by clicking the file name:

GitLab - DL file 1 of 2

… then the little cloud-looking icon:

GitLab - DL file 2 of 2

What the hell are these 'user-whatever' files anyway?

It's where we're going to store a truck load of browser settings. Just know you aren't cool if you don't have them.


Next you'll need a decent code editor with syntax highlighting. If you're running Wintendo (that's my derogatory name for "Windows"), PSPad is nice, simple and free. If you're running Linux you've already got something installed. Poke around.

What you need to do now is open that user-overrides.js file in your code editor and read the comments in it Very Carefully! Every single little thing you could ever possibly need to know is in there (except whatever i forgot to put in there).

Now that you've sifted through that convoluted mess (go you!), open Firefox's about:profiles page again. Note that user profiles and web cache are stored in separate folders, thus why you may see more than one directory path for each profile. In the row labeled 'Root Directory' under your 'privacy' profile, click the 'Open Directory' button and then kill Firefox.

In your file manager you may have noticed that the folder containing your 'privacy' profile actually has a longer name with a bunch of gobbledygook in front of 'profile'. Ignore that like you ignore your goofy neighbor with the tinfoil wallpaper. If you see a prefs.js file in there, then you're probably in the right place. Next, grab those files from your desktop you pirated earlier and stick 'em in your 'privacy' profile folder where the prefs.js file resides.

Now don't start Firefox with your 'privacy' profile anymore until i say it's OK! OK?

Pro TIp: DIY furniture

This looks fun…


Now we need to run that updater script. How to do that depends on whether…'re using Linux

You will need to make those .sh files executable. You could try meditation or sacrificing a chicken, but it'd probably be quicker to just right-click on each of them to open the file properties dialog window and on the 'Permissions' tab, click the 'Is executable' (or similar) checkbox. If your file browser doesn't have such an option, see How do I run .sh files?.

We need to run that script from a terminal, so open one and change the directory to your 'privacy' profile directory. In the example below you'll need to change 'gobbledygook' to match the correct name of your profile folder (and don't include the '$' sign):

$ cd ~/.mozilla/firefox/gobbledygook.privacy/

Let's double check to make sure we're in the right directory by using 'ls' to list the directory contents:

$ ls

The output should be… times.json user.js user-overrides.js

…and possibly those couple of 'dot' files.

If all looks good, run the script by preceding the file name with a dot and a slash:

$ ./



...or you're using Wintendo

To run that updater.bat script, hold down the Shift key and right-click in an empty space where the file is, then select "Open Command Window Here". Enter the name of the script and hit Enter. If you have trouble, see How to Run a BAT File on Windows: 13 Steps (with Pictures).


The updater script will spit out some introductory stuff and then prompt you to continue. If by chance everything in the universe is aligned just so, and you've followed the directions, the script will download a fresh copy of the 'ghacks' user.js file and then append the contents of your user-overrides.js to it just like it says on the tin.

Fattening the Fox

We're going to go to the Firefox Add-ons website and No. Where. Else. (except here) because we first need to install some protection. Start (or restart) Firefox and select your 'privacy' profile (yes, it's OK now), then come back here.

One at a time, middle click each of the links below to open their pages in a new tab, then Read What Their Pages Say and install them. Firefox will display some notices prior to installation and you can just click your way through to allow the install just like you click your way through all those 'Terms of Service' agreements you never read. Don't make a habit of installing add-ons that way though or you'll be sorry!!! If any of the links are dead, let me know and don't install something you think is equivalent.

Once you have all those installed, find the 'Customize' option in one of the Firefox menus or by right-clicking on a toolbar somewhere and drag the toolbar icons for your add-ons to wherever you like on the toolbar. ClearURLs, CSS Exfil Protection, Decentraleyes, Don't touch my tabs!, HTTPZ and POOP can be dragged to the overflow menu since you will rarely be interacting with these.

Neutering the Wild World Web (and the Fox)

We need to configure some of the add-ons we installed, but first a word to the wise: Unless you know what you're doing (and you probably wouldn't be here if you did), configure these add-ons as suggested.

To configure your add-ons, load about:addons in the address bar or find the 'Add-ons' menu item in one of the Firefox menus.

Clear URLs: Click the toolbar button and make sure the 'Filter' and 'Badges' options are enabled. The rest are optional.

Pro Tip

Remember the good ol' days when every program had a menu toolbar with stuff like File and Edit and Help on it? Press your Alt key.


Decentraleyes: Click the 'Options' button and select the following options where [X] indicates the option is enabled:

[X] Display injection counts on icon
[_] Block requests for missing resources
[X] Disable link prefetching
[X] Strip metadata from allowed requests
Exclude domains from inspection (leave this empty)

Privacy-Oriented Origin Policy: Click the 'Options' button and configure it like so:

Set the 'Global mode' to 'relaxed'.

In the 'Exclusions' section, enablee 'Exclude root domain matches', then paste the following code in the big text box below that. It'll come in handy if you ever switch POOP to its 'aggressive' mode: * *
* *

In the 'Other' section, make sure 'Spoof cross-origin Referer' is enabled, and don't blame me for the spelling. Long story.

uBlock Origin: This is a huge biggie! I know, supposed to be the 'for dummies' guide and you're not a quantum field propulsion scientist, but you really have to learn how to use uBlock Origin (uBO). The good news: It's got a 'dummy' mode and it's enabled by default!

uBlock open dashboard
click me

Although there's an 'Options' button for uBO in Firefox's about:addons page, let's ignore that and get accustomed to working with this powerful little doohickey from its toolbar icon (that little red shield thingy). Click that, then click the 'dashboard' icon.

Make sure the 'Settings' tab is selected at the top, then enable the following options where [X] indicates the option is enabled:

[_] Hide placeholders of blocked elements
[X] Show the number of blocked requests on the icon
[_] Make use of context menu where appropriate
[_] Disable tooltips
[_] Color-blind friendly
[_] Enable cloud storage support
[_] I am an advanced user (required reading)

DO NOT select the 'I am an advanced user' option! Don't look at it. Don't think about it. Don't think about looking at it … at least not until you read all that 'required reading' stuff and understand fully what uBO is, does, how to configure it, and how easy it is to break the interwebs if you don't know what you're doing. Did i scare you? Totally intentional.

In the 'Privacy' section, enable the following options where [X] indicates the option is enabled:

[X] Disable pre-fetching
[X] Disable hyperlink auditing
[X] Prevent WebRTC from leaking local IP addresses
[X] Block CSP reports

In the 'Default behavior' section, enable the following options where [X] indicates… You know.

[X] Disable cosmetic filtering
[_] Block media elements larger than kB
[_] Block remote fonts (enable this later after you read about its purpose)
[X] Disable JavaScript

Now switch to the 'Filter lists' tab and enable only those listed below. Because this section is long i'll list only the filters we will enable rather then listing all the check boxes. You may have to expand each section by clicking those little '+' things to reveal all the options:

Why does he say 'WE' when 'I' am the one doing all the f'n work?!

Plausible deniability. If i screw something up that causes your computer to implode, it's your fault.


Beginning at the top, WE want to enable the following:

Auto-update filter lists
Ignore generic cosmetic filters

My filters

In the 'Built-in' section, enable all the filters with the exception of 'uBlock filters – Experimental​​​​​​​​'.

In the 'Ads' , 'Privacy' and 'Malware domains' sections, enable all the filters.

​​In the 'Annoyances' section, enable the following:

Adguard's Annoyance List​​​
Fanboy's Cookie List​

​​In the 'Multipurpose' section, enable these:

Dan Pollock's hosts file​​​
Peter Lowe's Ad and tracking server list​

Don't worry about the 'Regions, languages' section unless you browse sites in those languages.

Training the Foxineer

If you've used Firefox before, there's going to be some changes. One of them is that you'll be searching from the search bar (or a web page that isn't Google hopefully) instead of the address bar. The reason for this is a little creepy, suffice to say it's a privacy/security thing. Live search suggestions are also disabled (also a creepy privacy/security thing), though the search bar will still suggest all kinds of other things, such as stuff from your history, bookmarks and previous searches for 'girls with big…'.

Now for the biggie: uBlock Origin. Remember the part at the beginning when you started reading this last week? Where i said we would be "breaking as few websites as possible"? Lie! Since we disabled JavaScript globally in uBO, every other website you visit is going to be busted.

OK, first off there's a few things you need to know about JavaScript: 1), it's awesome-ish, 2) it's a privacy nIGhTMarE, 3) almost every website uses it (even this one).

JavaScript (JS) can be used to do all kinds of cool (and annoying) things like make web pages interactive, make dull things look un-dull, animate stuff, etc.. It's used a lot for making navigation menus work. It can also do really bad things. JS is leveraged heavily for tracking and profiling you, your web browser, your computer, your finger prints, DNA and worse, and thus it's a privacy (and security) nightmare. Now do you see why we disabled JS globally in uBO? Thing is, it's very easy to enable again for those specific websites where you really need it to be enabled. "Need", i said. Not "like" or "want", but "need"!

uBO - enable JS
click me

If you're not already using your 'privacy' profile, restart Firefox and load it up, then middle-click this link to open it in a new tab. Click some of the colors on the color swatch and…… well that was boring, but WAIT! Now click the uBlock Origin button on your toolbar and in the lower right corner there's an icon that looks like </>, except it has a red 'X' through it. That icon is secret code for [CENSORED]. Click it to remove the 'X' and you will have enabled JavaScript for that particular website and you'll then see a new button appear with circle-ly arrows.

uBO - JS enabled
click me

Clicking that button will refresh the page at and this time your browser will allow JS to run for the domain. The page will now look very different and this time when you click on the color swatch, awesome things will appear that will surely keep you busy for hours on end (like that damned triangle puzzle-peg thingy in every Cracker Barrel).

The point of this barely interesting exercise was to demonstrate the power of JavaScript and show you how different it can make a page or entire website look, as well as how necessary it is in some, but not all cases. If you have your 'privacy' profile loaded, you may have been reading this nail-biting page-turner with JS disabled and never knew it, the point being that JS is also used do things behind the scenes and this is where things can get dangerous for us privacy geeks.

Now you're going to take the JavaScript oath. DON'T LAUGH! This is important! Repeat after me:


Now it's time for me to make another cup of nice hot coffee from some freshly ground beans, but you don't get a break! You're going to learn how to use uBlock Origin. You're going to read this and this and, finally, this, but only up to the 'Medium mode' part.

Lastly, if you're not a first-time user and you have important bookmarks you need to save, go ahead and transfer that stuff to your 'privacy' profile.

What to do when the Fox bites

It's inevitable that you're going to have trouble with some websites. Keep calm. Breeeeath! This where having more than one profile comes in handy. You've already gotten a taste of how a website can be rendered useless with JavaScript disabled and although i let you enable it for that site, i only did so because it's a trustworthy place, more or less. The next website you visit may not be (you're here aren't you? Kidding!).

So my advice is to use uBlock Origin to enable the functionality you need for websites which you trust. If you cannot get a website to cooperate by making site specific changes in uBlock, you can always spin-up a fresh, empty profile, but understand that you will now be at the mercy of a completely default Firefox configuration with all of our extra privacy protections removed. For websites you don't trust, don't disable any protections ever and, secondly, why are you visiting them? Porn? Warez? Forget it. Seriously.

The point here is to not disable any protection globally for all websites when using your daily-driver 'privacy' profile. If you have to adjust something for a particular website which you trust, fine, but use other profiles if you need to make extensive changes.

Another problem that will probably creep up at some point is a website not saving settings that you wanted to save. This is the fault of the Site Bleacher add-on which deletes most of what websites store in your Firefox profile, including 'cookies'. If you want to save site settings or preserve the ability to log-on automatically, then click the little bleach bottle icon on your toolbar and whitelist the website. I would not suggest whitelisting any privacy-hating social media site or mainstream search websites like Google or Yahoo.

The Fox hole

Congratulations! You've slogged through every snake infested swamp i've placed in your path … almost.

Even with everything we've done, you're still vulnerable to being tracked and profiled, however you're in better position then you were, except for one little problem. Know what it is?

answer inside...

Your Internet Service Provider! Did you forget already???


At the very least your ISP can tell what websites you visit, what files you download, when you're surfing the web and when you're not. They may even inject ads, malware and other junk in your data stream. The solution: Hijack your neighbors unprotected WiFi and… Kidding! Listen, you and i have gotten to know each other throughout this difficult ordeal. We're kinda like buddies now. Kinda. And i can already tell you're ethics are of a higher caliber than mine that!

One solution to the problem is a Virtual Private Network (VPN). Ever wanted to be in 30 places at once?

A VPN works by encrypting the traffic between you and another computer run by the VPN service provider which we'll call an 'exit node'. That exit node could be anywhere in the world. From there your traffic flows as normal to whatever website you want to visit (that has good kitty videos). That website then sends the kitty vid you clicked on back to the exit node thinking IT is YOU, but alas, it is NOT! The video then secretly makes its way back to you through this secret tunnel which was secretly established between you and the exit node. So far as the website is concerned, it doesn't know your real physical location. Ever annoyed by that galactically stupid "Sorry, this video is not available in your country" crap? Pfff. And as far as your ISP is concerned, all it sees is gobbledygook that looks like Braille to a blind pet rock with no fingers.

There are truck loads of different VPN service providers and it seems not a lot take customer privacy all that seriously, however i think both NordVPN and AirVPN are good companies that offer a good service at a good price. I've used both and i like both. Both have servers (think 'exit nodes') all around the globe and neither restrict any protocols (think 'BitTorrent'). Both offer client applications that you can install to make using their service stupid simple. If you'd prefer to pick a VPN provider yourself however, i recommend you visit That One Privacy Site and browse the fantastic spreadsheets that dude puts together. Another good resource is TorrentFreak's annual VPN reviews. Here's the one for 2018.

The downside? Though VPN services are cheap, it's still an additional expense. VPN exit node IP addresses can become blacklisted which could cause problems sending mail and accessing certain services on the web, however in my experience this hasn't often been an issue and, even if is is, it's usually just a couple of mouse clicks to switch exit nodes. Latency (the time between the mother-in-law jumping in front of you and your realization that you need to slam on the breaks) and bandwidth (how many tweets per second you can send to your friends notifying them of the "accident") will be affected, but in my experience the difference is usually minimal. In short, i think the pluses far outweigh the minuses, especially for us privacy conscious folks. That said, you can never trust any VPN service 100%, but any reputable one should be OK for general web surfing and it should certainly prevent your ISP from spying on you.


So now you're all smitten thinking you're invincible and ready to hack NASA to see if aliens really built hotels on the back of the moon (they did, pretty sure). You're not, but you've taken one, small step for man, and on….. Truth is, there's probably far more vectors for attack than even i know about, so don't get all uppity. Perfect privacy for us casual web users is a pipe dream and that wasn't the goal here anyway. We've covered a few important bases that will help to prevent websites (and your ISP) from tracking and profiling you, but not all of them. Remember that when you're creating fake profiles on Facebook to stalk your ex (you should probably use Tor for that).

After you've taken plenty of time to get comfortable with your new Firefox configuration, i suggest reading everything in the uBlock Origin wiki and learning how to use it in its advanced mode. And after that, it's the Firefox Configuration Guide for Privacy Freaks and Performance Buffs.

Be safe. Be ethical. And if you need help (after you've tried to help yourself), leave a comment.

IMPORTANT: If you incorporate suggestions made in this guide, please subscribe to the Firefox category on the subscription page. This article is updated fairly often and it's the best way to stay informed.

Further resources


Click to expand...


  • first (pre) release


  • added more info about using the user.js updater and prefsCleaner scrips
  • many small changes and polishing


  • polishing, clarifications


  • clarified a lot of stuff that may not have been clarified clearly enough
  • eliminated the 'relaxed_user-overrides.js' file – the user-overrides.js is now used for both the advanced and dummy guides
  • updated the user-overrides.js file
  • lots of minor edits, corrections


  • clarified info regarding the downloading of the configuration files


  • added better description and screen-caps for how to download user-overrides.js
  • minor edit


  • minor edit


  • added HTTPZ
  • added Site Bleacher and associated information
  • removed temporary profile info
  • lots of minor edits


  • added instructions for enabling the search bar in the navigation bar since setting the preference alone in user.js doesn't work for some reason
  • minor edits


  • added a warning about using this guide with Tor
  • added a resources section

21 thoughts on “The Firefox Privacy Guide For Dummies!”

  1. Does anyone get this error when running the

    ./ line 7: syntax error near unexpected token `newline'
    ./ line 7: `'

    … and does anyone know what to do about this?

    I have tried running dos2unix on the file, after of course having made it executable, but this doesn't make the error disappear. Thank you for any help!

  2. @Pants; @12Bytes

    Exactly. The problem was with pref "security.cert_pinning.enforcement_level" having a value of '2' (strict). I solved it by changing the value to '1' in "user-overrides.js" by

    When I read these comments and thought about it, I decided to follow it up in good faith.

    Uninstalled Adguard ad blocker from the system. I had a lifetime license to use it two PCs and three smartphones/tabs. Frankly speaking, I uninstalled it reluctantly. It was my money sitting in the system tray and the browser doing its thing. Then I disabled these components in Kaspersky:

    1) Mozilla Firefox and Thunderbird
    Scan secure traffic in Mozilla applications
    If secure traffic scan is enabled, access to websites via the HTTPS protocol may be blocked. (This setting is buried inside somewhere. If you disable only 2-5 below, it doesn't help as far as Firefox is concerned).

    2) Safe Money
    Protects your data on websites of banks and payment systems.

    3) Traffic processing
    Inject script into web traffic to interact with web pages.

    4) Private Browsing
    Protects against collection of information about your activities on websites.

    5) Anti-Banner
    Blocks banners on websites and in some applications.

    Went back to "user-overrides.js" by and deleted the added line: user_pref("security.cert_pinning.enforcement_level", 1); // 0=disabled 1=allow user MiTM (such as your antivirus), 2=strict. And updated the user.js by using updater.bat and prefsCleaner.bat.

    Firefox is blazing fast without issues (barring Invalid request. Err 2034C). The UI of uMatrix is different now. It doesn't display any Adguard or Kaspersky elements. Using uMatrix and uBlock Origin is pleasant and straight forward. Web sites load faster and cleaner.

    Now, is there a solution for this: Invalid request. Err 2034C. It happens when I try to login to a site using my Google id.

    Thank you guys for your invaluable help.

    1. Went back to "user-overrides.js" by and deleted the added line: user_pref("security.cert_pinning.enforcement_level", 1);

      that's a mistake, and maybe i need to make it clearer in the 'dummy' guide; you never edit any existing prefs in prefs.js, user.js or user-overrides.js (assuming you're using mine) – any pref you want to change you need to copy to the appropriate section of user-overrides.js (near the bottom) where you can then change it's value

      or if you just want to test something, you can change the value using about:config without editing any files but of course it will be changed back upon restart (which is what you experienced earlier because user.js had a different value)

      in this case you're ok because you deleted a pref in user-overrides that exists in user.js and so Firefox reset the value to '2' upon restart as you probably expected it would, but if you make a habit messing with the default prefs in any of the aforementioned files, you'll make updating them far more difficult

      as for your new error, had you poked around on the web you might have come across a potential clue: CSRF – and if you search the user.js (the ghacks one) for 'csrf' you might find more clues

      are you spoofing the http referrer? perhaps with an add-on? or did you change that pref?

      there's several things you can do to troubleshoot – one is to spin up a new, default FF profile (about:profiles) and connect to the site you have trouble with – if you can then connect, this will tell you there's an issue in your other profile and so the hunt is on – to solve these issues yourself, see this.

      this can be frustrating at first, but once you get the kinks worked out things will go much smoother

      let me know how you made out

      1. Went back to "user-overrides.js" by and deleted the added line: user_pref("security.cert_pinning.enforcement_level", 1);

        that's a mistake, and maybe i need to make it clearer in the 'dummy' guide; you never edit any existing prefs in prefs.js, user.js or user-overrides.js (assuming you're using mine) – any pref you want to change you need to copy to the appropriate section of user-overrides.js (near the bottom) where you can then change it's value

        But it was not a line that existed in your user-.js, no? I added it as a solution to the '2'(strict) problem I had because of the AV. And I deleted it as it deemed fit to my uninformed thinking. Please clarify.

        I'll follow up the other hints and post. Regards.

        1. i think i confused you because i'm not explaining things clearly – let's see if this helps…

          you should NEVER edit/delete/comment out any of the existing prefs in prefs.js OR user.js IF you are using the 'ghacks' user.js

          you should NEVER edit/delete/comment out any of the existing prefs in user-overrides.js IF you are using mine with the following exception: if you need to change anything in the 'ghacks' user.js, or my user-overrides.js, you should COPY the entire line you want to change to the USER CUSTOMIZATION section near the end of my user-overrides.js where you can then change the preference value

          if you are NOT using my user-overrides, but you still have one, then you can edit it all you want

          if you are using the 'ghacks' user.js, then, unless you do not want to change anything in it, you should be using a user-overrides.js (mine or otherwise) along with their script

          does that clear things up? :)

          1. perhaps i should also add to that that having multiple instances of the same preference in any of the config files does not present any problem – Firefox reads the config files from the top down (prefs.js, then user.js), so if there's duplicate prefs, the value for the last one will be applied

            user.js (or user-overrides.js):

            user_pref("this", true);
            user_pref("this", true);
            user_pref("this", false);


              1. don't know what to say about that – seems it's usually attributed to google, though possibly not always

                i would create a new, empty profile for testing and then copy into it everything from your privacy profile EXCEPT prefs.js and user.js – if you still have the problem, then it may be an add-on – if you don't, then it's likely something in user.js in which case i'd then copy that to the testing profile and do this

          2. "if you are using the 'ghacks' user.js, then, unless you do not want to change anything in it, you should be using a user-overrides.js (mine or otherwise) along with their script".

            Very clear. No doubts about it now. Thank you.

  3. I read about using 'user.js'for configuring Firefox browser in a German blog (in English translation) and a book (German, translated into English). Then I read about it in and finally in 12bytes.o rg. This quest was the continuation of my fascination with rooting my Android smartphone.

    This particular section of titled "The Firefox Privacy Guide For Dummies!" is intended to help novices (dummies) like me. But, the sad truth is that dummies rarely seek help, because they don't know that they need help. Help for what? For safeguarding themselves on Internet. The greatest impediment is the attitude that "I don't have anything to hide from anybody". In fact, it's the height of ignorance.

    As long as common man views Google, Microsoft, Facebook, Twitter, etc., as knights on a mission to save humanity from ignorance, laziness and loneliness, there's no way to help him see the the truth. For example, I stopped using WhatsApp and asked all my contacts who mattered to me to give it up and adopt Telegram instead. (I can see the author of laughing at me for the folly of my choice). Very little success.

    Fortunately, the author of "The Firefox Privacy Guide For Dummies!" has taken all these facts into account. Otherwise why should he painstakingly do "The Firefox Privacy Guide For Dummies!" section? The section "Firefox Configuration Guide for Privacy Freaks and Performance Buffs" would have been sufficient.

    I read both these sections a couple of times before deciding that I was not a dummy (because I've been using Firefox browser for so long)! So, I took "Firefox Configuration Guide for Privacy Freaks and Performance Buffs" as my guide and proceed to tame my Fox.

    Everything went fine. The browser (a new installation after uninstalling and deleting all traces of the previous one) configuration amazed me because it was super fast now and had very few add-ons. The web pages looked clean as if I was reading printed content on white paper. No shenanigans. Nothing!

    But suddenly trouble cropped up: No Google domains opened (and some other sites). I cross checked the configuration. Everything was fine. And that was the real problem: Everything worked as they should but I lacked knowledge and skill to tweak things when necessary. My prejudices (I've been using Firefox for so long, after all) had prevented me from beginning from the beginning: The Firefox Privacy Guide For Dummies!

    The author of was gracious enough to help me identify the problem and solve it. Did he solve it for me? Not really. He showed me how to solve it by leading me back to "The Firefox Privacy Guide For Dummies" section.

    Now you know where to begin. From the very beginning itself.

    Why should people like the author of this blog take the pain to offer their knowledge, skill, time and effort to us unasked? He and I are hemispheres apart.

    Maybe, because they know the true meaning of the trite saying: Sharing is caring. And they have commitment.

    1. The greatest impediment is the attitude that "I don't have anything to hide from anybody". In fact, it's the height of ignorance.

      very well said!!!

      Why should people like the author of this blog take the pain to offer their knowledge, skill, time and effort to us unasked? He and I are hemispheres apart.

      we're all human beings sharing one tiny planet and from that perspective you're just around the corner :)

      thanks much for your kind comments Murali, and i'm glad you persevered

      for the record, the problem in this case was the pref security.cert_pinning.enforcement_level having a value of '2' (strict), which is the current default in the 'ghacks' user.js – i don't understand this pref fully, but apparently that caused a problem with this persons anti-virus

      1. > the problem in this case was the pref security.cert_pinning.enforcement_level having a value of '2'

        No, the problem was the end user allows AV to act as a MitM and slurp up all his browser traffic. Personally, browsers are some of the most secure and protected pieces of software on the planet (by default: e.g among others, Safe Browsing lists curated by Google, which has the resources to do this right – e.g constantly adding protections for xss and other mechanisms, and MOAR), not to mention if you have Tracking Protection and/or uBlock Origin (and/or uMatrix) with blocklists and hosts lists and controlling JS etc – that forget about the tracking – the ATTACK surface is massively reduced

        At the end of the day, most damage is done by the end users (social engineering, visiting suspect websites, falling for BS), and the real solution here is to cut out the middle man – configure that AV to not interfere with web traffic.

        PS: "Don't touch my tabs" vs earthlng's "window opener be gone"
        – xpi is here: )
        – see

        1. i realize that completely and it wasn't my intention to imply that the problem was with the user.js – perhaps i should have worded it better – what i meant was that this pref caused a problem in this case for this user

          the guy is a good guy and he's trying, but no one is born knowledgeable – i politely scolded him in emails we exchanged about running Windows and 2 AV's and now he's interested in giving Linux a spin

          and thanks much for the window.opener info – i didn't realize earthing's worked differently

            1. these AV "suites" ARE a virus! the only proper way to uninstall some/many/all of them is to reinstall the OS – i learned long ago in my Windows days that a resident AV scanner is largely unnecessary, at best, provided the user is smart about what they do on-line and they use a decent on-demand scanner

              as i've said in this article, trusting your AV to keep you safe is like trusting guard rails to keep your car on the road

              thanks for the info – it reinforces my decision to keep 'security.cert_pinning.enforcement_level' at '1', at least for now

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