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Re: windows NTLM auth with sspi enabled fails mysteriously for some customers

From: Ray Satiro via curl-library <>
Date: Thu, 27 Feb 2020 18:32:41 -0500

On 2/27/2020 5:26 PM, Daniel Stenberg via curl-library wrote:
> On Thu, 27 Feb 2020, Zach Hall via curl-library wrote:
>> build with command line option ENABLE_SSPI=yes. For our environment
>> and the
>> vast majority of our customers' environments, this hasn't caused a
>> problem,
>> However for some it causes login failures. I had one of the customers
>> with
>> this problem test logging in with a libcurl.dll built with
>> installed in our install directory and they could login without issue.
>> Any clue why this might be happening?
> The primary reason we support "ENABLE_SSPI=yes" builds in addition to
> having our own native NTLM implmentation is because of the existance
> of subtle differences in implementations and what they support.
> Unfortunately, NTLM is a tricky beast (in my humble opinion) and to
> figure out the exact differences between the implementations we'd have
> to run two builds with otherwise same credentials against a fixed
> server and try to reverse engineeer and understand what SSPI does and
> compare to our own implementation. An interesting task no doubt, but
> also challenging and most likely quite time consuming.

The only issue I can think of that may possibly be related is

Received on 2020-02-28