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RE: Problem with NTLM proxy authentication

From: Steve Holme <>
Date: Wed, 10 Sep 2014 08:00:38 +0100

On Tue, 09 Sep 2014, Ulrich Telle wrote:

> > Where these on the same proxy server?

Thanks for the extra information. That may help but I'd like to explore a
couple of other things first...

> It is really strange that Windows SSPI doesn't work for my application
> and the users in that one company. It is even stranger, because the
> user I'm in contact with to perform the tests has no problem to
> access the Internet using his FireFox browser. And as far as I know
> FireFox uses Windows SSPI, too.


> I intend to analyze the NTLM handshake of FireFox with the proxy
> server. I will have an opportunity to do so on Thursday. Maybe this
> can give additional hints.
> No idea, what triggers this different set of flags.
> One difference I see in the source code of the SSPI authentication
> module of FireFox is that SSPI function InitializeSecurityContext is
> called without any of the flags libcurl is using:

I wonder whether we are being "too strict" in some respects. The libcurl
NTLM SSPI code (as far as I can remember) has been like that for years.

Have you tried and if not can you try removing some or even all of those
flags and passing 0 in your version of libcurl?

Kind Regards

List admin:
Received on 2014-09-10