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Re: Kerberos/GSSAPI issues

Dieter Kluenter wrote:
Am Wed, 29 Dec 2010 16:50:17 +0000
schrieb Brian Candler<B.Candler@pobox.com>:

On Wed, Dec 29, 2010 at 07:57:43AM +0100, Dieter Kluenter wrote:
The default ssf of ldapi is 71, but you may change localSSF in

Thank you, that is very clear.

Having changed that, I can use EXTERNAL with minssf=112, but not
GSSAPI.  I find that if I set minssf=56 it's fine, but at minssf=57
it isn't.

It looks like this is a fundamental limitation of the GSSAPI:

FYI, here's what I see with minssf=57 (the 'No such attribute' error
is somewhat confusing)

root@noc:~# ldapsearch
ldap_sasl_interactive_bind_s: No such attribute (16)
root@noc:~# ldapsearch -Y GSSAPI
SASL/GSSAPI authentication started
ldap_sasl_interactive_bind_s: Inappropriate authentication (48)
	additional info: SASL(-15): mechanism too weak for this user:
mech GSSAPI is too weak

That is because Kerberos DES, und thus GSSAPI, only has a security
strength factor of 56.

But this value is pure fiction, it's an arbitrary value hardcoded into the SASL gssapi plugin. Generally Kerberos is using triple-DES today, or AES.

  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/