NTLM is 100% supported on IE and FF, on other browsers can be problems. Opera 12 should support NTLM (atleast it is mentioned in articles) Opera 9.01 and later versions can use NTLM/Negotiate, but will use Basic or Digest authentication if that is offered by the server. http://my.opera.com/community/forums...dml?id=1117922 http://my.opera.com/smtpster/blog/2012/05/21/opera-windows-authentication-support http://en.wikipedia.org/wiki/Integra...Authentication Try