[Samba] Samba4/Windows DNS replication and administration issue

[Pete Storkey]

Hi all,

I am having trouble with DNS replication between a Linux/Samba 4.0.9 box and Windows Server 2012 domain controller, as well as administering the Linux DNS from the Windows DNS Manager snap-in.

First a little background. I am trying to integrate a Samba 4.0.9 server as a domain controller in an existing Windows Active Directory domain. The domain and forest are at Windows 2008R2 functional level with a single domain controller which was upgraded from Windows Server 2008 R2 to Windows Server 2012.

I am running CentOS 6.4 x64, patched to current levels. I downloaded and installed the Sernet binaries for Samba 4.0.9 but ran into problems joining the domain. It failed with the following error:

ERROR: no subClassOf 'top' for 'samDomain'
I found a bug report for this error at https://bugzilla.samba.org/show_bug.cgi?id=8680 and rebuilt the Sernet RPMs with the patches implemented. This time I was able to successfully join the domain. Replication seems to be working but I do get a warning from samba-tool drs showrepl:

==== KCC CONNECTION OBJECTS ====

Connection --
Connection name: 3c20a62a-ad94-40ef-b346-ba8b15f829f8
Enabled : TRUE
Server DNS name : server.example.com
Server DN name : CN=NTDS Settings,CN=server,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=example,DC=com
TransportType: RPC
options: 0x00000001
Warning: No NC replicated for Connection!

The inbound and outbound neighbors all appear to be ok.

I started out with internal DNS but when I was unable to get it working correctly, I switched to bind (Centos package bind-9.8.2-0.17.rc1.el6_4.6.x86_64).

The problem is that when I try to administer DNS through the Windows DNS Manager snap-in, my forward domain fails to load, with an error indicating zone data may be corrupt (it opens fine on the Windows DNS server). Additionally, my reverse zone does not appear to have replicated to the Linux server.

When I click on the forward zone in DNS Manager, I see the following in /var/log/messages:

smbd[24043]: [2013/09/01 15:30:21.091035, 0] ../source3/rpc_server/svcctl/srv_svcctl_nt.c:326(_svcctl_OpenServiceW)
smbd[24043]: _svcctl_OpenServiceW: Failed to get a valid security descriptorfree_pipe_context: destroying talloc pool of size 275
samba[19596]: [2013/09/01 15:30:25.505483, 0] ../source4/rpc_server/dnsserver/dcerpc_dnsserver.c:1068(dnsserver_query_zone)
samba[19596]: dnsserver: Invalid zone operation IsSigneddnsserver: Invalid zone operation IsSigneddnsserver: Invalid zone operation IsSigneddnsserver: Found Unhandled DNS record type=49dnsserver: Found Unhandled DNS record type=49dnsserver: Found Unhandled DNS record type=49dnsserver: Found Unhandled DNS record type=49ndr_push_error(2): Bad switch value 49 at default/librpc/gen_ndr/ndr_dnsserver.c:544
samba[19596]: [2013/09/01 15:30:26.272723, 0] ../source4/rpc_server/dnsserver/dnsdata.c:354(dnsp_to_dns_copy)
samba[19596]: dnsserver: Found Unhandled DNS record type=49dnsserver: Found Unhandled DNS record type=49dnsserver: Found Unhandled DNS record type=49dnsserver: Found Unhandled DNS record type=49ndr_push_error(2): Bad switch value 49 at default/librpc/gen_ndr/ndr_dnsserver.c:544

Querying DNS via nslookup/dig/host works fine but querying through samba-tool gives an error:

# samba-tool dns query server.domain.com domain.com @ ALL
GENSEC backend 'gssapi_spnego' registered
GENSEC backend 'gssapi_krb5' registered
GENSEC backend 'gssapi_krb5_sasl' registered
GENSEC backend 'sasl-DIGEST-MD5' registered
GENSEC backend 'schannel' registered
GENSEC backend 'spnego' registered
GENSEC backend 'ntlmssp' registered
GENSEC backend 'krb5' registered
GENSEC backend 'fake_gssapi_krb5' registered
Using binding ncacn_ip_tcp:server.example.com[,sign]
ERROR(runtime): uncaught exception - (-1073545204, 'NT_STATUS_RPC_BAD_STUB_DATA')
File "/usr/lib64/python2.6/site-packages/samba/netcmd/__init__.py", line 175, in _run
return self.run(*args, **kwargs)
File "/usr/lib64/python2.6/site-packages/samba/netcmd/dns.py", line 974, in run
None, record_type, select_flags, None, None)

and I see the following in /var/log/messages:

samba[19596]: [2013/09/01 15:31:55.207112, 0] ../source4/rpc_server/dnsserver/dnsdata.c:354(dnsp_to_dns_copy)
samba[19596]: dnsserver: Found Unhandled DNS record type=49dnsserver: Found Unhandled DNS record type=49dnsserver: Found Unhandled DNS record type=49dnsserver: Found Unhandled DNS record type=49ndr_push_error(2): Bad switch value 49 at default/librpc/gen_ndr/ndr_dnsserver.c:544

Any help would be much appreciated.

Thanks,

Pete
--
To unsubscribe from this list go to the following URL and read the
instructions: https://lists.samba.org/mailman/options/samba

[Peter Storkey]

[Pete Storkey]

t looks as though I have a bad key in my dns.keytab. I see the following messages in /var/named/data/named.run:

process_gsstkey(): dns_tsigerror_badkey

If I manually trigger replication from the Linux/samba server, I see denied messages for dynamic dns updates coming from the windows server in /var/log/messages:

# samba-tool drs replicate server.domain.com windowsserver.domain.com dc=domain,dc=com

named[24467]: samba_dlz: starting transaction on zone _msdcs.domain.com
named[24467]: client 192.168.0.2#62937: update '_msdcs.domain.com/IN' denied
named[24467]: samba_dlz: cancelling transaction on zone _msdcs.domain.com

If I manually trigger replication from the Windows server via Active Directory Sites and Services, I get an error dialog about DomainDnsZones.domain.com naming context in the process of being removed or is not replicated from the specified server.

named.conf has the following line:

tkey-gssapi-keytab "/var/lib/samba/private/dns.keytab";

I have tried manually recreating dns.keytab:

# samba-tool domain exportkeytab --principal=DNS/server.domain.com /var/lib/samba/private/dns.keytab
# samba-tool domain exportkeytab --principal=DNS/windowsserver.domain.com /var/lib/samba/private/dns.keytab

The contents of dns.keytab are as follows:

# ktutil
ktutil: read_kt /var/lib/samba/private/dns.keytab
ktutil: list
slot KVNO Principal
---- ---- ---------------------------------------------------------------------
1 1 DNS/server.d...@DOMAIN.COM
2 1 DNS/server.d...@DOMAIN.COM
3 1 DNS/server.d...@DOMAIN.COM
4 31 DNS/windowsserve...@DOMAIN.COM
5 31 DNS/windowsserve...@DOMAIN.COM
6 31 DNS/windowsserve...@DOMAIN.COM
7 31 DNS/windowsserve...@DOMAIN.COM

The problem persists after recreating dns.keytab and restarting Samba and Bind daemons.

Is this the correct way to generate the dns.keytab? Is there anything I'm missing?

Thanks,

Pete

[steve]

On Thu, 2013-09-05 at 20:39 -0700, Pete Storkey wrote:

>
> I have tried manually recreating dns.keytab:
>
> # samba-tool domain exportkeytab --principal=DNS/server.domain.com /var/lib/samba/private/dns.keytab
> # samba-tool domain exportkeytab --principal=DNS/windowsserver.domain.com /var/lib/samba/private/dns.keytab
>

That syntax seems wrong.
# samba-tool domain exportkeytab /path/to/dns.keytab
--principal=server1.your.domain

> The contents of dns.keytab are as follows:
>
> # ktutil
> ktutil: read_kt /var/lib/samba/private/dns.keytab
> ktutil: list
> slot KVNO Principal
> ---- ---- ---------------------------------------------------------------------
> 1 1 DNS/server.d...@DOMAIN.COM
> 2 1 DNS/server.d...@DOMAIN.COM
> 3 1 DNS/server.d...@DOMAIN.COM
> 4 31 DNS/windowsserve...@DOMAIN.COM
> 5 31 DNS/windowsserve...@DOMAIN.COM
> 6 31 DNS/windowsserve...@DOMAIN.COM
> 7 31 DNS/windowsserve...@DOMAIN.COM
>
> The problem persists after recreating dns.keytab and restarting Samba and Bind daemons.
>
> Is this the correct way to generate the dns.keytab? Is there anything I'm missing?

Maybe you didn't recreate the keytab? Look for the timestamp:
klist -kte /path/to/dns.keytab

The only difference I can see with our keytab is that we have:
DNS/fqdn@REALM
and
short-hostname@REALM

Maybe this isn't a keytab issue?
HTH
Steve