Firefox enable windows authentication

To enable windows authentication on your domain.

1. Open Firefox

2. Enter on url textbox: about:config

3. Locate the following preference names and put as the value the comma separated values of the address roots.

network.automatic-ntlm-auth.trusted-uris
network.negotiate-auth.delegation-uris
network.negotiate-auth.trusted-uris

Your value should look something like this: localhost, server1, server2, serverX, something.com

Reference: here