It can be annoying when you are forced to re-authenticate when connecting to a web site that accepts your domain NTLM authentication. FireFox has a way to make this pass-through so you don’t have to deal with the authentication as you go from internal website to internal website.
Type about:config in your FireFox toolbar.
This will bring up the internal config editor, which allows you to set all kinds of properties that influence Firefox’s behavior. Look for the key called network.automatic-ntlm-auth.trusted-uris. Set that key’s value to a comma separated list of servers you want NTLM authentication for. For example, to authenticate automatically to a server named SP, add a WINS entry and DNS entry:
Add any other servers on the same line and separate the names with commas. Your websites will authenticate automatically.