Today, I got an request to enforce various Firefox settings globally for all users on several Linux hosts.
All you have to do is creating two files in your Firefox installation directory (usually /usr/lib/firefox):
File: $FIREFOX_INSTALL_DIR/defaults/pref/000-local-config
// The file must start with a comment line
pref("general.config.filename", "local-config.js");
pref("general.config.obscure_value", 0);
File: $FIREFOX_INSTALL_DIR/local-config.js
// The file must start with a comment line
// Enforce the use of a Web Proxy Autodiscovery file
lockPref("network.proxy.autoconfig_url", "http://wpad.somedomain.com/wpad.dat");
lockPref("network.proxy.type", 2);
// Disable Firefox Save Per Side Download Feature
pref("browser.download.lastDir.savePerSite", false);
// Disable Firefox Displaying History in New Tabs
pref("browser.newtabpage.enabled", false);
pref("browser.newtabpage.url", "about:blank");
Setting set using the lockPref() function cannot be changed by the users (they are greyed out). Everything that has been set using the pref() function is valid unless the user overrides the setting.
This procedure has been tested with Firefox 23.
