How to Setup Firefox to use Windows Authentication


If you have an ASP.NET application that is behind an IIS Web Server and it configured to use Windows authentication or what they called trusted login. Typically you can download a plugin for Firefox and it will help you perform windows authentication automatically. What if you are not allowed install any plugin or don’t want to use any plugin.

When you try to connect to a ASP.NET application via Windows authentication it will display they following error message:

I have a solution that I have learn from someone else and I am sharing the secrets of Firefox settings. These settings are hidden and you have to be very careful when accessing.

  • Open Firefox and type About:Config in the address bar
  • Then it will display an error message and just confirm that you will be careful

  • Now, in the search-box search for ntlm and it will bring a window similar to the following window and then double click on it.

  • Now, provide the computer name of the Web server (IIS machine name). What you are telling Firefox here is that it is ok to pass the windows credentials to this machine.


Just keep in mind that you have to proceed with caution because if you break something you ma have re-install Firefox.