Firefox Mandatory Preferences

1. Important links

   • http://kb.mozillazine.org/Locking_preferences

   • http://kb.mozillazine.org/About:config_entries

   • http://kb.mozillazine.org/Installation_directory

   • http://www.alain.knaff.lu/%7Eaknaff/howto/MozillaCustomization/cgi/byteshf.cgi

   • obscure-tool is in the firefox-dev package "sudo apt-get install firefox-dev"

Overall Process

1. We want to create mandatory preferences for Firefox
2. As an example we are setting

   1. The Firefox homepage to: https://help.ubuntu.com/community/FirefoxMandatoryPreferences

   2. The proxy settings to: Auto-detect proxy settings for this network

3. More settings can be found About:config description of the Mozilla

Knowledgebase

Determine settings

• open Firefox
• go to "about:config"
• search for "general.config"

  • You will be presented with the default values (these could be changed in /usr/lib/firefox/greprefs/all.js)

• We now know that the file to create is firefox.cfg. The location for this is the Firefox Application folder.

• Create a file firefox.txt. It's content will be:

//
lockPref("network.proxy.type", 4);
lockPref("browser.startup.homepage", "https://help.ubuntu.com/community/FirefoxMandatoryPreferences");

NOTE: The two slashes at the first line of the file are important otherwise Firefox won't understand your config file and refuse to start up

• OPTIONAL: Ubuntu ships with a default firefox.cfg file /usr/lib/firefox/firefox.cfg make a backup of that file

  • sudo cp /usr/lib/firefox/firefox.cfg /usr/lib/firefox/firefox.cfg.dist

• sudo /usr/lib/firefox/obscure-tool firefox.txt /usr/lib/firefox/firefox.cfg
• Restart Firefox

  • Go to Edit -> Preferences -> Advanced -> Network -> Settings

  • All values should be greyed out and the selected Value should be Auto-detect proxy settings for this network

  • Go to Edit -> Preferences -> Main

  • The value of the homepage should show https://help.ubuntu.com/community/FirefoxMandatoryPreferences - changing that value shouldn't be possible as the field is greyed out.

    • NOTE: The button above is not disabled in this config. A user may very well show a blank page on startup instead of the homepage. But hitting the Home button will take her to the homepage we set.

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