Let’s look at the process of configuring the Firefox browser to meet your company’s needs. Let’s take the Ubuntu 17.10 platform and Firefox 59 as an example. The process will also be identical to what you will have to go through on Windows and macOS systems, the only difference will be the paths where the files are located.

You will need to download the latest version of the Firefox browser, as well as uninstall the version that was previously installed. We will also need a terminal window.

Download the latest version of Firefox into the ~/Downloads directory. Now you are ready for the step-by-step instructions below.

Unpacking the file

The first thing we need to do is unzip the downloaded file. Open a terminal and go to the ~/Downloads directory with the command “cd ~/Downloads”. Extract the file using the command “”. tar xvfj firefox-*.bz2. This command creates a separate folder named firefox-XX (XX is the release number).

Inside that folder is another folder, firefox. It should be extracted from the parent directory with the following command:

cd firefox-XX (where XX is the release number)
mv firefox ../
cd ../

Now you should see the firefox folder. Type cd firefox in the terminal. Now you’re ready to configure your browser.

Configure Firefox

The first thing we do is create a file named mozilla.cfg – use the command nano mozilla.cfg. In this file, we will explicitly specify what settings from about:config we will block to users. The first line of the file is always ignored, so we will just add an empty comment there:


The following lines will contain all configuration options. To lock a certain setting in about:config, the line must start with “lockPref”. For example, we want to explicitly specify the browser home page and also prohibit it from being changed. We enter:

lockPref(“browser.startup.homepage”), “”);

To see what other options you can specify in this file, just open the about:config page. Let’s look at another example: you can lock app.update.enabled (this will prevent the program from updating) using the following line:

lockPref(“app.update.enabled”, false);

You can also lock the default browser check:

lockPref(“”, false);

When you have decided on the options you want to lock and you have put all the necessary lines into the mozilla.cfg file, save it and close it. After that we need to run the command (in the current firefox directory):

nano default/pref/autoconfig.js In this file we add the following lines:

pref(“general.config.obscure_value”, 0);
pref(“general.config.filename”, “mozilla.cfg”);

Save and close that file.

Let’s test our configuration

We open Firefox with ./firefox. Once the browser is up, you can see your configuration in action. To check that everything is set up exactly the way you wanted, open the about:config page, try to change the settings you blocked earlier.

If they are configured correctly, they should be locked out.

Figure 1: Locked settings

Deploying Customized Firefox

Since we are using Linux, the whole process will be pretty simple. We just need to move the firefox directory to /opt. To do this, we run the command:

sudo mv firefox /opt

Next, we will create a symbolic link to /usr/bin with the command:

ln -s /opt/firefox/firefox /usr/bin/firefox

Now we can use the firefox command at the command line to start our customized version of the Firefox browser. After launching the program, pin its icon on the panel.

Depending on your desktop environment, you may need to manually configure the application shortcut. To do this, open a terminal window and type the command:

nano ~/.local/share/applications/firefox.desktop

After that, add the following content:

[Desktop Entry]
Terminal=false Icon=/opt/firefox/browser/chrome/icons/default/default48.png Type=Application

Save and close this file. The new launcher should now appear on your desktop.


That’s basically all you need to do to keep your company safe from especially gifted employees who like to poke around in the settings and can hurt your company’s policies. If your organization uses the Firefox browser, this tutorial is a great solution until Firefox for Enterprise comes out.

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