[Samba] Serverinfo Error

[Tim Beale]

On 26/07/19 5:10 AM, Robert A Wooldridge via samba wrote:
> Did this and restarted samba as well as winbind and still the same
> result:
> athena:~# samba-tool dns serverinfo athena
> ERROR(runtime): uncaught exception - (9717,
> 'WERR_DNS_ERROR_DS_UNAVAILABLE')
>   File "/usr/lib/python2.7/dist-packages/samba/netcmd/__init__.py",
> line 177, in _run
>     return self.run(*args, **kwargs)
>   File "/usr/lib/python2.7/dist-packages/samba/netcmd/dns.py", line
> 564, in run
>     None, 'ServerInfo')
What's happening here is the RPC server process is trying to open a
database connection and load some basic DNS info, and this is failing.
Some DNS operations, such as updating records, get performed via this
particular DCE/RPC interface. These operations will likely all fail for
the same reason.

Basically, this is not good.

When the Windows DC replies to the samba-tool RPC request, it's using a
completely different server implementation that behaves differently.
This is why you don't see the problem talking to the Windows DC.

I think the connecting to the database is OK. The problem is probably
something to do with the DNS records.

One possibility is this is a boot-strapping problem, as you had to
comment out the samba-tool code that added the DC records in order to
join. Either the records you added manually weren't quite right, or
samba_dnsupdate couldn't run properly to add the correct DNS records.

The other option is it could be some hangover from using an older
Windows schema (2003, right?). Most samba testing gets done against a
2008R2 schema. Longer-term, you probably want to upgrade your schema and
preparation level to 2008R2. This may or may not help in this case, but
it's a good idea in the long-run. There's some more info here:
https://wiki.samba.org/index.php/Windows_2012_Server_compatibility#Pre-2008R2_functional_level

I'm not an expert in the DNS area, but these are the 2 obvious
possibilities that stand out to me.

To start with, I'd suggest trying to get more debug out of what's going
wrong:
1. Sanity-check 'samba-tool processes' output on the samba DC. You
should hopefully see a 'dnssrv' process. (Although, the output might be
slightly different on older samba releases. Sorry, I can't remember
exactly).
2. Sanity-check your samba server log for errors. Especially if you see
something about the DNS server exiting.
3. Restart the samba server with a higher log level (3). Then repeat the
'samba-tool dns serverinfo athena' command. See if the logs on the
server tells you more about the failure. You should see some 'dnsserver:
Found DNS zone <blah>' messages.