On 3/24/25 09:47, support | IT visibility via Dnsmasq-discuss wrote:
Hi *,
I’m using dnsmasq with a few vlan interfaces and each interface is tagged.
And running tests with pihole as well as native dnsmasq.
An example on how this is setup in both cases (.i.e. pihole as well as
native dnsmsaq):
=====
# Wired - vlan 210
interface=eth0.210
domain=wired.lan,192.168.210.0/24,local
dhcp-range=set:vlan-210,192.168.210.11,192.168.210.99,168h
dhcp-option=tag:vlan-210,option:router,192.168.210.241
dhcp-option=tag:vlan-210,option:dns-server,192.168.210.235
dhcp-option=tag:vlan-210,option:ntp-server,192.168.210.235
dhcp-option=tag:vlan-210,option:domain-name,wired.lan
=====
The idea behind this is that devices with multiple vlan interfaces have
their IP’s registered with dhcp and dns.
The dhcp part seems to work – all interfaces have the correct IP details.
However, the log has numerous wrong-address errors like this (i.e.
pihole as well as native dnsmasq):
=====
Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPREQUEST(eth0.210) 192.168.210.201
bc:24:11:87:be:e5
Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPNAK(eth0.210) 192.168.210.201
bc:24:11:87:be:e5 wrong address
Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPDISCOVER(eth0.210) bc:24:11:87:be:e5
Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPOFFER(eth0.210) 192.168.210.201
bc:24:11:87:be:e5
Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPREQUEST(eth0.210) 192.168.210.201
bc:24:11:87:be:e5
Mar 24 09:02:03 dnsmasq-dhcp[49]: DHCPACK(eth0.210) 192.168.210.201
bc:24:11:87:be:e5 osiris
=====
*Question-1*: where are these wrong-address messages coming from?
If I look at the dhcp.leases (Pihole) or dnsmasq.leases (native dnsmasq)
there is always one entry like this:
1743408124 bc:24:11:87:be:e5 192.168.230.201 osiris *
*Question-2*: why is there only an entry from the last vlan interface of
(in this example) osiris? And not one for every vlan interface?
*Question-3*: the same applies for dns regestrations where there is only
an entry for the last vlan interface?
I have tried to force this dns regestration for all fqdn’s for each vlan
using the following settings (i.e. pihole as well as native dnsmasq):
dhcp-ignore-clid
dhcp-fqdn
dhcp-client-update
expand-hosts
domain-needed
domain=lan
local=/lan/
Does the above ring any bells? Any suggestion?
With warm regards – Will
Answer 1: Because a lease exists for the relevant MAC address with a
different IP address to the address it's requesting.
Answer 2: Because the device is using the same MAC address on all the
VLANS it's talking through. The MAC address is supposed to be unique: a
DHCP server won't allow a MAC address to have more than one lease.
Answer 3: Partly the same answer as 2, but even if you use unique MAC
addresses (or client-ids) dnsmasq will only associate a DNS name with at
most one DHCP lease. That's a design decision.
Cheers,
Simon.
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