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Re: [msmtp-users] GSSAPI, NTLM LOGIN ? problematic Re: GSSAPI error in client



Hi Simon!

On Wed, 21 Jan 2015 15:28:17 +0100, Simon Josefsson wrote:
> That's true for CRAM-MD5, but not for SCRAM-SHA1.  SCRAM-SHA1 allows
> the server to only store a hash, so it is nice.  However, that makes
> it harder to in the future migrate to another mechanism which uses
> another hash.  I would say SCRAM-SHA1 is still better than CRAM-MD5,
> DIGEST-MD5, and PLAIN though.

Thanks for this information! I got that wrong.

> > For the special case of authentication via TLS client certificates,
> > method EXTERNAL may be used.
> 
> Yep.  Alas, it is a bit underspecified whether EXTERNAL means
> TLS-and-client-certs or something else.  You need to out-of-band
> policy agreement about this between client and server.

Yes, and sometimes TLS-with-client-certs is used but a
confirmation via EXTERNAL is not supported.

> > These three methods are really the only useful ones now, as far as I
> > can see.
> 
> GSSAPI and GS2-KRB5 are useful for Kerberos people. 

Yes, but I have never encountered these Kerberos people ;)
Do you know in which scenarios Kerberos is actually being used?

> There ought to be some checks to make sure GSSAPI/GS2 isn't selected
> if it is likely that it won't succeed (e.g., no Kerberos tickets
> available).  I thought GNU SASL checked that, but I'm not confident.

Probably GNU SASL checks this. Msmtp does not use
gsasl_client_suggest_mechanism(), but chooses the method itself.
I did some digging to find out why. Currently a comment reads
"TODO: use gsasl_client_suggest_mechanism()?".
In msmtp-1.2.2 (more than ten years ago) that comment read
"Do not use gsasl_client_suggest_mechanism() because it seems to always
return ANONYMOUS (libgsasl 0.0.7)".
I guess that problem was solved in the meantime...

Thanks for your work on all the essential libraries that msmtp depends
on!

Regards,
Martin

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