[*SP4M*] DHCPd only updating the forward zone

[Dan Egli]

Actually, the issue at hand is that there is no trace of venus left at all. I killed dhcpd and named, then removed the journal files and ensured that venus wasn't listed in the main zone file (it wasn't). Then I removed the dhcpd.leases file and created a new one. After restarting bind and dhcpd I rebooted venus (which is only booting from a RO squashfs at the moment), and let it request an address. What you see below is what the logs show. DHCPd didn't even TRY to register it, even though as far as it's config files can tell this is a brand new registration.

I thought it should work too. So why is dhcpd not even trying to add the machine to the DNS?

On Mon, Dec 21, 2020 at 11:27:54AM +0000, Simon Hobson wrote:
> Dan Egli <dan at newideatest.site> wrote:
> 
> >> What do the logs for both DNS and DHCP show when this happens ?
> >> 
> >> 
> > dhcpd.log:
> > Dec 20 20:55:57 pluto dhcpd[1129]: DHCPDISCOVER from 08:00:27:03:d3:23 via enp0s8
> > Dec 20 20:55:58 pluto dhcpd[1129]: DHCPOFFER on 192.168.10.128 to 08:00:27:03:d3:23 (venus) via enp0s8
> > Dec 20 20:55:58 pluto dhcpd[1129]: DHCPREQUEST for 192.168.10.128 (192.168.10.1) from 08:00:27:03:d3:23 (venus) via enp0s8
> > Dec 20 20:55:58 pluto dhcpd[1129]: DHCPACK on 192.168.10.128 to 08:00:27:03:d3:23 (venus) via enp0s8
> > 
> > No entries at all in named.log now that it's started not making dynamic updates at all. The named.log shows startup messages, and nothing else.
> 
> That would be normal - once the DNS is updated, dhcpd won't send further updates until something changes - such as a lease timing out or being released. You could either release the lease from the client, let it expire, or shut down dhcpd and manually remove the DNS entries from the lease.
> 
> What we're looking for is to see if dhcpd tries to update and fails, or doesn't try at all.
> 
> > As to the name server, it would be pluto actually, not jupiter.
> 
> Oops, my mistake there.
> 
> 
> > I don't know what's up, but there's no update of DNS at all right now. I'm stumped. As far as I can tell, all is fine in the config.
> 
> Yes, it all looks fine and should "just work automagically"
> 
> 
> What should happen is dhcpd looks up the SOA record for the zone (sorry, I should have asked for that rather than NS records) to find the primary authoritative name server for the relevant zone - it will then send updates to that server. I can see from your previous message that pluto is given in both zones - so both updates should work. As far as I can see, everything is setup correctly for this to work.
> 
> There is an argument for using signed zone updates - but IMO that's not really necessary for a small home setup like this. There you define a key, add zone directives to the dhcp config, and reference the key (rather than an IP based ACL) in the allow updates directives in your dns setup.