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Re: [serf-dev] [Patch] Adding NTLM Support to Serf - Work in progress / Subversion regression

From: <kmradke_at_rockwellcollins.com>
Date: Thu, 20 Jun 2013 10:49:58 -0500

> Did you read my email above? Let me explain again. Server advertises
> supported authentication schemes, for example Microsoft IIS:
> [[[
> C: GET / HTTP/1.1
> S: HTTP/1.1 401 Authorization Required
> S: WWW-Authenticate: NTLM
> S: WWW-Authenticate: Negotiate
> S: WWW-Authenticate: Basic
> ]]]
>
> Then client decide which authentication scheme to use. Serf tries to
> Negotiate, then Basic. But with proposed patch serf will try
> Negotiate, then Basic and then NTLM again, which is wrong because NTLM
> authentication already handled inside Negotiate protocol. This is one
> of the reasons why I vetoed this patch.
>
> My point is that serf should use NTLM *only* if server doesn't
> advertise support Negotiate.

The problem is that most clients will choose Kerberos instead of
NTLM during the Negotiate phase (which they should because it is
considered more secure), but there may be things that cause
Kerberos to fail, such as mis-configure SPNs in active directory
or a mis-configured Java VM options on the client. In most of
these cases NTLM "just works", but the serf client never tries it
like neon did. This is why most installations will be set to
offer NTLM only and not Negotiate.

As stated, the correct action is to have Serf use NTLM if that
is the only thing the server offers. Not just fail like
it does today.

Kevin R.
Received on 2013-06-20 17:50:34 CEST

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