I m trying to do Html extraction from web pages using commons httpclient. I managed to find a way to supply credentials to sites that require Basic Authentication but sites with NTLM authentication are throwing exception(InvalidCredentialsException). I tried to search about NTLM and found that there is a TYPE1,2,3 messages that are sent between client and server. But i dont understand it much. Can some one explain NTLM and also tell if there is a way to do this html extraction from sites that have this Authentication mechanism?