[Dnsmasq-discuss] DHCP, dhclient logs errors

[Simon Kelley]

Adam Hardy wrote:
> Hello List,
> 
> after running smoothly for months, my network went snafu today and in 
> the process of putting it back to normal, I found errors logged into 
> /var/log/messages from dhclient on my main workstation.
> 
> I didn't get this issue before IIRC
> 
> It makes me wonder if I have installed something from debian which is 
> causing the problem ('Unable to add forward map...')
> 
> I get precious little from my google and mailing list searches. Is this 
> a problem due to packages like mDNS or Avahi-daemon [1]  - or could it 
> be my iptables rules which have thrown a spanner in the works? (which I 
> also changed since my dnsmasq install).
> 
> 
> Mar 17 16:32:37 localhost dhclient: DHCPREQUEST on eth0 to 192.168.0.2 
> port 67
> Mar 17 16:32:37 localhost dhclient: DHCPACK from 192.168.0.2
> Mar 17 16:32:37 localhost dhclient: bound to 192.168.0.235 -- renewal in 
> 1631 seconds.
> Mar 17 16:32:38 localhost dhclient: Unable to add forward map from 
> gondor.localdomain. to 192.168.0.235: destination address required
> Mar 17 16:59:48 localhost dhclient: DHCPREQUEST on eth0 to 192.168.0.2 
> port 67
> Mar 17 16:59:48 localhost dhclient: DHCPACK from 192.168.0.2
> Mar 17 16:59:48 localhost dhclient: bound to 192.168.0.235 -- renewal in 
> 1226 seconds.
> Mar 17 16:59:49 localhost dhclient: Unable to add forward map from 
> gondor.localdomain. to 192.168.0.235: destination address required
> 
> 
> regards
> Adam
> 
> [1] suspicious:
> Mar 17 16:05:33 localhost avahi-daemon[2292]: New relevant interface 
> eth0.IPv4 for mDNS.
> Mar 17 16:05:33 localhost avahi-daemon[2292]: Joining mDNS multicast 
> group on interface eth0.IPv4 with address 192.168.0.235.Mar 17 16:05:33 
> localhost avahi-daemon[2292]: Registering new address record for 
> 192.168.0.235 on eth0.
> M
> 
It looks like dhclient is trying to update it's DNS records in a DNS
server using the dynamic-dns protocol. I doubt that this is anything to
do with avahi. More likely a change in dhclient configuration.
Do you have something like "do-forward-updates true;" in dhclient.conf?

If you are using dnsmasq, you don't need to use DDNS updates: the
dnsmasq DNS server doesn't support them, but it doesn't need them
because DNS records are inserted automatically from DHCP addresses.

Simon.