[Dnsmasq-discuss] What does this 'wrong server-ID' message mean?

[Chris Green]

On Tue, Feb 05, 2019 at 09:44:19PM +0000, Chris Green wrote:
> I'm having a minor problem with my laptop and 'roaming WiFi', I've
> just noticed the following sequence in syslog on the system that runs
> as my DHCP/DNS server running dnsmasq:-
> 
>     Feb  5 21:32:52 dns dnsmasq-dhcp[385]: DHCPDISCOVER(eth0) 00:28:f8:3d:3b:aa
>     Feb  5 21:32:52 dns dnsmasq-dhcp[385]: DHCPOFFER(eth0) 192.168.1.92 00:28:f8:3d:3b:aa
>     Feb  5 21:32:55 dns dnsmasq-dhcp[385]: DHCPDISCOVER(eth0) 00:28:f8:3d:3b:aa
>     Feb  5 21:32:55 dns dnsmasq-dhcp[385]: DHCPOFFER(eth0) 192.168.1.92 00:28:f8:3d:3b:aa
>     Feb  5 21:32:55 dns dnsmasq-dhcp[385]: DHCPREQUEST(eth0) 192.168.1.102 00:28:f8:3d:3b:aa
> Feb 5 21:32:55 dns dnsmasq-dhcp[385]: DHCPNAK(eth0) 192.168.1.102 00:28:f8:3d:3b:aa 
> wrong server-ID 
>     Feb  5 21:33:24 dns dnsmasq-dhcp[385]: DHCPREQUEST(eth0) 192.168.1.92 00:28:f8:3d:3b:aa 
>     Feb  5 21:33:24 dns dnsmasq-dhcp[385]: DHCPACK(eth0) 192.168.1.92 00:28:f8:3d:3b:aa t470
>     Feb  5 21:33:24 dns dnsmasq-dhcp[385]: DHCPDISCOVER(eth0) 00:28:f8:3d:3b:aa
>     Feb  5 21:33:24 dns dnsmasq-dhcp[385]: DHCPOFFER(eth0) 192.168.1.92 00:28:f8:3d:3b:aa
>     Feb  5 21:33:24 dns dnsmasq-dhcp[385]: DHCPREQUEST(eth0) 192.168.1.102 00:28:f8:3d:3b:aa
> Feb 5 21:33:24 dns dnsmasq-dhcp[385]: DHCPNAK(eth0) 192.168.1.102 00:28:f8:3d:3b:aa 
> wrong server-ID 
>     Feb  5 21:33:29 dns dnsmasq-dhcp[385]: DHCPREQUEST(eth0) 192.168.1.100 7c:67:a2:57:6c:78
> Feb 5 21:33:29 dns dnsmasq-dhcp[385]: DHCPACK(eth0) 192.168.1.100 7c:67:a2:57:6c:78 
> DESKTOP-2S4CP78 
>     Feb  5 21:33:35 dns dnsmasq-dhcp[385]: DHCPREQUEST(eth0) 192.168.1.100 7c:67:a2:57:6c:78
> Feb 5 21:33:35 dns dnsmasq-dhcp[385]: DHCPACK(eth0) 192.168.1.100 7c:67:a2:57:6c:78 
> DESKTOP-2S4CP78 
>     Feb  5 21:34:39 dns dnsmasq-dhcp[385]: DHCPREQUEST(eth0) 192.168.1.100 7c:67:a2:57:6c:78
> Feb 5 21:34:39 dns dnsmasq-dhcp[385]: DHCPACK(eth0) 192.168.1.100 7c:67:a2:57:6c:78 
> DESKTOP-2S4CP78 
>     Feb  5 21:34:45 dns dnsmasq-dhcp[385]: DHCPREQUEST(eth0) 192.168.1.100 7c:67:a2:57:6c:78
> Feb 5 21:34:45 dns dnsmasq-dhcp[385]: DHCPACK(eth0) 192.168.1.100 7c:67:a2:57:6c:78 
> DESKTOP-2S4CP78 
>     Feb  5 21:35:37 dns systemd[1]: Started Session c4 of user chris.
>     Feb  5 21:36:44 dns dnsmasq-dhcp[385]: DHCPREQUEST(eth0) 192.168.1.100 7c:67:a2:57:6c:78
> Feb 5 21:36:44 dns dnsmasq-dhcp[385]: DHCPACK(eth0) 192.168.1.100 7c:67:a2:57:6c:78 
> DESKTOP-2S4CP78 
>     Feb  5 21:36:45 dns dnsmasq-dhcp[385]: DHCPREQUEST(eth0) 192.168.1.100 7c:67:a2:57:6c:78
> Feb 5 21:36:45 dns dnsmasq-dhcp[385]: DHCPACK(eth0) 192.168.1.100 7c:67:a2:57:6c:78 
> DESKTOP-2S4CP78 
>     Feb  5 21:37:14 dns dnsmasq-dhcp[385]: DHCPDISCOVER(eth0) 7c:67:a2:57:6c:78
>     Feb  5 21:37:14 dns dnsmasq-dhcp[385]: DHCPOFFER(eth0) 192.168.1.100 7c:67:a2:57:6c:78
>     Feb  5 21:37:14 dns dnsmasq-dhcp[385]: DHCPDISCOVER(eth0) 7c:67:a2:57:6c:78
> 
> So what's happening around that DHCPNAK message?
> 
Oops!  I've just noticed I had another DHCP server running on the LAN!
I guess that might explain it.

-- 
Chris Green