[Samba] Internal DNS - TTL enforcement for dynamic updates

Dmitry Khromov icechrome at gmail.com
Thu Nov 1 04:55:02 MDT 2012

> > I expected Samba to behave like MS DNS server and replace the old
> > record with a new one.
> Yes, that should work. If it doesn't work for you, you need to tell us
> some more details about your smb.conf and maybe provide a network
> capture of the failing DNS update.

# cat etc/smb.conf
# Global parameters
        workgroup = MK_KLIN
        realm = klin.kifato-mk.com
        netbios name = DC1
        interfaces =,
        bind interfaces only = Yes
        server role = active directory domain controller
        idmap_ldb:use rfc2307  = yes
        debug level = 1
        wins server =
        allow dns updates = secure only

        path = /usr/local/samba/var/locks/sysvol/klin.kifato-mk.com/scripts
        read only = No

        path = /usr/local/samba/var/locks/sysvol
        read only = No

PCAP-formatted dump is attached. According to the dump, Windows just doesn't try to send a signed update after receiveng TKEY. However, this host had succeded at least once today. Rebooted it, now no updates happen, but Samba started to say:
[2012/11/01 14:32:30,  1] ../source4/dns_server/dns_server.c:150(dns_process_send)
  Failed to verify TSIG!
Some background: we already had the same symptoms this week for most of our Windows hosts (and some Samba 3 based, too). Yesterday we had to delete the zone (it was somewhat dirty after years on Windows, e.g. MMC DNS said "Server couldn't load the zone" when you open it on Samba server) and rebuilt it from scratch. As a side effect those TSIG-related messages had gone and records had started to update (one time until deletion). Now it looks like nothing had actually changed.

> Again, we probably need a network capture to see what's
> going on with the DNS MMC failing to update the SOA record.

Attached (PCAP-formatted).

Thanks in advance.
Best regards,
Dmitry Khromov

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