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Re: NTLM Proxy Authentication and SSL

From: Daniel Stenberg <>
Date: Tue, 28 Aug 2007 13:16:32 +0200 (CEST)

On Mon, 27 Aug 2007, Paul Mecklar wrote:

> I cannot get proxy authentication working when authenticating via NTLM and
> using an SSL URL. Libcurl is returning a 407 error from the proxy server.
> SSL and proxy authentication work fine via Digest and Basic authentication,
> and the NTLM authentication works fine when not using SSL. When using IE to
> go to the same URL with the same proxy settings everything works fine, so I
> am reasonably certain it is not a configuration issue with the proxy server.
> According to Ethereal libcurl gets to the point where it sends the
> NTLMSSP_AUTH request, and the proxy is returning HTTP 200, but according to
> libcurl the request failed with a 407.
> Any suggestions as to what I could try?

NTLM works identically over SSL or not so I fail to see how that changes
anything really...

Instead of using ethereal/wireshark to see what happens over the wire, I
suggest you use CURLOPT_DEBUGFUNCTION (feel free to copy some code from this
example: to dump the
complete incoming and outgoing headers and data.

Then verify that it truly gets a 200 back but thinks it is a 407 as then it
must be some major confusion on libcurl's behalf that needs to be addressed.

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Received on 2007-08-28