Problems with GSSAPI and LDAP

Aki Tuomi aki.tuomi at
Tue Oct 11 07:18:32 UTC 2016

On 11.10.2016 10:13, Juha Koho wrote:
> Hello,
> I have a Dovecot 2.2.25 set up with OpenLDAP back end. I was trying to
> set up a GSSAPI Kerberos authentication with the LDAP server but with
> little success. Seems no matter what I try I end up with the following
> error message:
> dovecot: auth: Error: LDAP: binding failed (dn
> (imap/ at EXAMPLE.COM)): Local error, SASL(-1): generic
> failure: GSSAPI Error: Unspecified GSS failure.  Minor code may
> provide more information (No Kerberos credentials available (default
> cache: FILE:/tmp/dovecot.krb5.ccache))
> I have set the import_environment in dovecot.conf:
> KRB5CCNAME=FILE:/tmp/dovecot.krb5.ccache
> And these in LDAP configuration:
> dn = imap/ at EXAMPLE.COM
> sasl_bind = yes
> sasl_mech = gssapi
> sasl_realm = EXAMPLE.COM
> sasl_authz_id = imap/ at EXAMPLE.COM
> I have tried with different values in dn and sasl_authz_id and also
> leaving them out completely but I always end up with the error message
> above. Using simple bind without GSSAPI works just fine.
> The credentials cache file exists and is valid for the principal
> imap/ at EXAMPLE.COM. The file is owned by dovecot user
> so it shouldn't be a permission problem either.
> GSSAPI in OpenLDAP works but I suppose it is irrelevant here since the
> connection attempt never reaches the LDAP server due to the error. I
> also have similar setup for Postfix and it works fine.
> Any ideas what to try next?
> Best regards,
> Juha

Can you provide klist output for the cache file? Also, it should be
readable by dovenull user, or whatever is configured as default_login_user.


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