Software Installations from Non-Mozilla Sites

The best source of Firefox extensions is Mozilla. Its website, at https://addons.update.mozilla.org/extensions/, lists popular extensions and optionally all available extensions.

Sometimes, however, you might want to install an extension that is not available on the Mozilla website. Before Firefox allows these to be installed, you need to approve, or allow, Firefox to do the installation. Allowing Firefox is done on a site-by-site basis (see Figure 5.6), as well as globally. Conservative users should simply uncheck Allow Web Sites to Install Software, whereas more advanced or trusting users should check the Allowed Sites list to control which sites may (or may not, if they are not in the list!) install software.