[Samba] Dynamic DNS u­pdates not working with B­IND DLZ

[Stephen Jones]

Hi Lucas,

Thanks for the suggestion but, unfortunately, it's not that.  I am
aware of the kerberos sensitivity to time differences.  When I
installed Samba4 I built a custom ntp rpm as the version shipped with
RHEL/CentOS does not support signed ntp.  I tested this by shifting the
clock on the client and it worked its way back again.

Out of interest I decided to try this again, some months after the
initial install.  My laptop's clock was about 10 sec off the DC.  I
changed it to 2 min, and it stays there.  Running 'w32tm /resync
/rediscover' just reports "no time data was available".

So I actually have 2 problems.  Dynamic dns updates, that DID work
before, now do not, and ntp updates, that DID work before, now also do
not.  Nothing has changed on the server with dns or ntp configuration.
 There is only the upgrade of Samba from 4.0.0 to 4.0.1.

It would seem that there is some problem with kerberos that the signed
requests fail.  Yet I can use kinit to authenticate and get a valid
ticket.  Kerberos is buried inside Samba so I have no idea what is
wrong with it and why, nor do I have any idea how to fix it.

I have trawled the web for hours on this.  I read plenty of similar
problems, but no solutions other than the obvious stuff I already
checked.  It's really very frustrating.

Regards,

Stephen Jones


On Tue, Apr 23, 2013, at 01:30 AM, ?icro MEGAS wrote:

  Hey there,
  had a similar problem in the past and resolved it today. The error
  was caused by time mismatch between the host and the client. Did you
  check that ntp is working fine and your time between samba4 and
  windows host is in sync (<5min) ?
  Lucas.
  Птн 12 Апр 2013 03:00:41 +0400, Stephen Jones
  <lloydsystems at fastmail.com.au> написал:

  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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