AS-REQ using SPN

Ralph Böhme slow at samba.org
Wed Nov 15 09:53:36 UTC 2017


Hi Garming,

On Wed, Nov 15, 2017 at 11:34:18AM +1300, Garming Sam wrote:
> I noticed that this behaviour of AS-REQ with a SPN was introduced a little
> while ago. It asserted that this is in line with Windows, but I have been
> making some attempts and have yet to see any Windows KDC manage to accept
> such a request (so something is not quite right, or I'm missing something).
> I've tried it against a 2008R2 and 2012R2 machine.

works here against Windows 2016:

[slow at kazak scratch]$ cat /etc/krb5.conf
[libdefaults]
        default_realm = RIVERSIDE.SITE
        dns_lookup_realm = false
        dns_lookup_kdc = false

[realms]
        RIVERSIDE.SITE = {
                 kdc = 10.10.11.14
        }

[slow at kazak scratch]$ bin/samba4ktutil foo.keytab 
foo/win2016.riverside.site at RIVERSIDE.SITE (des-cbc-crc)
foo/win2016.riverside.site at RIVERSIDE.SITE (des-cbc-md5)
foo/win2016.riverside.site at RIVERSIDE.SITE (arcfour-hmac-md5)
foo/win2016.riverside.site at RIVERSIDE.SITE (aes256-cts-hmac-sha1-96)
foo/win2016.riverside.site at RIVERSIDE.SITE (aes128-cts-hmac-sha1-96)

[slow at kazak scratch]$ bin/samba4kinit -k -t foo.keytab foo/win2016.riverside.site

[slow at kazak scratch]$ klist
Ticket cache: FILE:/tmp/krb5cc_1000
Default principal: foo/win2016.riverside.site at RIVERSIDE.SITE

Valid starting       Expires              Service principal
11/15/2017 10:51:12  11/15/2017 20:48:38  krbtgt/RIVERSIDE.SITE at RIVERSIDE.SITE

> I have also seen a Kerberos client attempt such a connection, but it fails
> to do any useful work as the TGS request will fail due to HDB_F_GET_ANY not
> being supplied (currently still HDB_F_GET_CLIENT) in subsequent database
> fetch calls. Is there a particular use case I don't really understand here?

Iirc I somehow noticed the difference in behaviour.

-slow

-- 
Ralph Boehme, Samba Team       https://samba.org/
Samba Developer, SerNet GmbH   https://sernet.de/en/samba/



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