[Samba] samba_dnsupdate

Paul Littlefield info at paully.co.uk
Mon Mar 2 13:36:04 UTC 2020

On 02/03/2020 13:16, Rowland Penny via samba wrote:
> Samba runs samba_dnsupgrade on a regular basis, using dns_update_list as a template. Amongst the list of dns entries is this:
> AAAA ${HOSTNAME}                                           $IP

Hi Rowland,

Thanks for replying so quickly.

OK, is there a way to pause this process for the purposes of debugging?

Can I change any of these which will not break my AD DC?

allow dns updates = secure only
dns update command = /usr/sbin/samba_dnsupdate

> I am unsure why it is doing this, I have never seen this happening, but then again I do not use IPv6 or netplan.

OK, so is it safe to (maybe at a future date) turn off IPv6 on Ubuntu and change to ifupdown if I want to?

> add 'log level = 4' to the smb.conf on the DC


>> 2. Can I watch for DNS requests in tcpdump?
> I do not see why you couldn't.

Done. Here are a few lines of santised output...

13:25:35.264891 IP > 29782 update [1a] [3n] SOA? mydomain.com. (108)
13:25:35.265196 IP > 29782 update Refused- 1/3/0 (Class 254) CNAME V-RDS02.mydomain.com. (108)
13:25:35.274443 IP > 64781 update [1a] [3n] [1au] SOA? mydomain.com. (239)
13:25:35.354349 IP > 64781 update 1/3/1 (Class 254) CNAME V-RDS02.mydomain.com. (224)

...what IS that Windows server trying to do?!

> Fairly sure this is samba_dnsupgrade doing this, but why is another question.

Oooo, goody... I've prompted a head scratching bug finding session!

Joking aside... to be honest, I really wish I didn't have people moaning at me because they keep getting kicked out of Sage but that's I.T. for you.

I look forward to your replies!

As always... thanks,



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