[Samba] Trouble with Kerberos authentication
Vinicius Bones Silva
vbs at e-trust.com.br
Tue Jul 11 14:27:41 UTC 2017
Did you create a kerberos keytab file to use with dovecot?
Also, make sure there's a reverse DNS entry for the dovecot server, kerberos usually fails
if the reverse address is not resolvable.
Em 11/07/2017 06:41, Mark Foley via samba escreveu:
> I'm not sure whether this is a Dovecot issue or a Samba issue, but as it deals with
> authentication I think it's worth trying the samba experts first.
> Here's the scenario ...
> I have an AD/DC running Samba 4.4.14. I have 3 AD users: mark, sue, dennis. Mark and Dennis
> use both Windows 7 and Linux (also running PAM-enabled Samba 4.4.14) domain member
> workstations. Sue is Windows 7 only. All are able to log onto the domain using their domain
> credentials and all are able to connect the the Dovcot mail server (also running on the AD/DC)
> from their workstations using Thunderbird and Kerberos/GSSAPI authentication.
> Dovecot authentication is set to auth_mechanisms = plain login gssapi. The first two mechanisms
> use /etc/passwd for authentication. The gssapi presumably uses gssapi and kerberos to
> authenticate via AD. I believe Dovecot tries these mechanisms in order, left-to-right.
> As it turns out, user Dennis also had an entry in /etc/passwd - yes, I know it shouldn't be
> there, but it was, although it did have the correct AD user and group IDs. No problem, I
> though, I'll just remove that entry.
> However, when I did that, Dennis was not longer able to authenticate from Thunderbird. He
> could still log into his Linux workstation. Tbird would give the error
> "The Kerberos/GSSAPI ticket was not accepted by the IMAP server ... please check that you are
> logged into the Kerberos/GSSAPI realm."
> Wnen I put Dennis back in /etc/passwd, with the correct domain password, he is able to
> authenticate from Thunderbird again.
> I know next to nothing about how kerberos works, but my theory is that Dennis' kerberos
> credentials somehow got associated with his /etc/passwd credentials, not his AD credentials and
> when the /etc/passwd entry is removed kerberos authentication fails. This is true on both his
> Linux and Windows workstations.
> I need to fix this so Dennis' AD credentials alone are used for authentication. How can I do
> btw, `getent passwd dennis` works just fine from Dennis' Linux workstation.
> Thanks --Mark
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vbs at e-trust.com.br
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