[Samba] Dynamic DNS updates not working with BIND DLZ

[Stephen Jones]

Hi Thomas,

Thanks for the information.  I did as you suggested and ran named in
debug mode and issued 'ipconfig /registerdns' from the client.  The
output was similar to your post:

failed gss_inquire_cred: GSSAPI error: Major = Unspecified GSS
failure.  Minor code may provide more information, Minor = Success.
gss-api source name (accept) is client_pc$@EXAMPLE.LOCAL
process_gsstkey(): dns_tsigerror_noerror

Looks like the server does not believe the client update request is
signed appropriately.  Strange, since I know Kerberos is setup fine and
works.  I can use nsupdate with Kerberos to edit the AD domain from the
command line.  Run 'kinit Administrator at EXAMPLE.LOCAL' gets a ticket,
then 'nsupdate -g' and I can add/remove DNS entries.

I know dynamic updates from the client worked before when I first setup
Samba4.  I don't know at what point it decided to stop working.  The
only thing I have done that I consider may have influence is upgrading
Samba to 4.0.1.

I don't really want to use the Samba internal DNS.  The server runs an
external domain as well as the internal AD domain with a split DNS
setup, and I may not be able to run BIND and Samba DNS together.  And
if MX and CNAME in the Samba DNS is broken then it's no good to me
running a mail server.  The BIND DLZ seems a much better option to me.

I certainly hope there is a fix for this problem.

Regards,

Stephen Jones


On Thu, Apr 11, 2013, at 09:01 PM, Thomas Simmons wrote:

On Wed, Apr 10, 2013 at 10:22 PM, Stephen Jones
<[1]lloydsystems at fastmail.com.au> wrote:

  Hi,
  A while ago I setup Samba4 on CentOS 6.  Samba version was 4.0.0
  using
  the RPM from SOGo.  I used the DLZ BIND backend with BIND 9.8.
  I tested with a Windows 7 VM client.  When I joined the client to
  the
  domain it was automatically added to the AD DNS and appeared in the
  Windows DNS Manager.  The VM had a static IP, but if I changed the
  IP
  address that change was automatically reflected in the DNS entry.
  I am now adding new real clients to the domain and find that they
  are
  not added to the AD domain DNS.  The client has a dynamic IP, but I
  have
  tried changing to a fixed IP address and it makes no difference.
  The only changes I can recall between the initial setup and now are:
  1. Samba upgrade to 4.0.1.  After upgrading I followed the procedure
  and
  ran
  samba-tool dbcheck --cross-ncs --fix
  samba-tool ntacl sysvolreset
  The upgrade changed the permissions of /var/lib/samba4/private back
  to
  root:root 700, which is no good, so I changed back to root:named
  750.
  I also added "server services = -dns" to smb.conf as per the
  instructions because internal DNS is now default.
  2. Tested OpenChange.  But, prior to doing anything I backed up
  entire
  /var/lib/samba4 directory.  When I removed OpenChange (as it is just
  not
  stable yet) I removed /var/lib/samba4 and replaced it with the
  backup.
  So this should not have any effect.
  I have checked everything against my notes made when installing
  Samba4
  and can't find anything wrong.  In terms of DNS, /etc/named.conf
  contains
  include "/var/lib/samba4/private/named.conf";
  which loads the DLZ module for BIND 9.8.
  The /etc/named.conf also has in the options
  tkey-gssapi-keytab "/var/lib/samba4/private/dns.keytab";
  Permissions of files:
  /var/lib/samba4/private/named.conf  root:named 640
  /var/lib/samba4/private/dns.keytab  root:named 640
  /var/lib/samba4/private/dns/  root:named 770
  It all seems OK (I think), but no dynamic DNS updates.  There is
  nothing
  in the samba.log file to suggest a problem.  The system log has
  messages
  client <IP address>: update 'example.local/IN' denied
  samba_dlz: cancelling transaction on zone example.local
  Is there something I need to set in smb.conf?  I see there are new
  options like "allow dns updates" and "dns update command", which I
  do
  not have specifically set, but I don't know if these only apply to
  Samba
  internal DNS.  There is still really no documentation about smb.conf
  for
  Samba4.
  Can someone please explain what might be wrong or what I should look
  for.



Hello Stephen,

I have been experiencing the same problem for the past month or so.
Unfortunately, I have been unable to find a solution. I was able to dig
back through my logs and found that the last DNS update occurred very
early in the morning, so for some reason it just stopped updating. You
can start bind in debugging mode "named -u named -g -d 5", then run
"ipconfig /registerdns" on the Windows client. If you see the
following, then you are experiencing the same issue:
28-Mar-2013 08:26:15.759 failed gss_inquire_cred: GSSAPI error: Major = Unspecif
ied GSS failure.  Minor code may provide more information, Minor = Success.
28-Mar-2013 08:26:15.760 failed gss_accept_sec_context: GSSAPI error: Major = Un
specified GSS failure.  Minor code may provide more information, Minor = .
28-Mar-2013 08:26:15.760 process_gsstkey(): dns_tsigerror_badkey

This is not a problem with the internal DNS server, so that may be a
solution. Do be advised that MX and CNAME records are broken in the
internal DNS server, so that may not work for you. I'm working on
migrating everything to Windows Server in my test environment. Since
there is no way to go back to Samba 3, that seems to be the only option
I have. Please let me know if you see the same errors with named in
debugging mode. Perhaps it's a different problem altogether.

  Regards,
  Stephen Jones
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References

1. mailto:lloydsystems at fastmail.com.au
2. https://lists.samba.org/mailman/options/samba