Multiple subnets with dnsmasq

Question

I've done some research on dnsmasq and its ability to DHCP several subnets, but it sadly only seems to work when there are multiple interfaces as shown in the configuration below:

interface=eth0
interface=eth1
interface=eth2
dhcp-range=192.168.0.100,192.168.0.200
dhcp-range=192.168.1.100,192.168.1.200
dhcp-range=192.168.2.100,192.168.2.200

However, I have not been able to see the possibility to have one interface, let's say eth0 to service multiple subnets, something along these lines:

interface=eth0
dhcp-range=192.168.0.100,192.168.2.200

Is this possible? If not by dnsmasq config, is there a work-around?

Thanks!

Solution

I believe this link answers your question:

http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2010q3/004415.html

Specifically:

At first glance, what you're doing doesn't make any sense. You have two subnets on one interface, which is fine, but the only thing that defines which subnet a machine is on is its IP address, and DHCP allocates that address. Before the address is allocated, all that's known about a machine is that it's on a particular physical network, there's no way to pin it down to a subnet.

Comments

[Tero Kilkanen]

You should not have two IP subnets in the same broadcast domain (Ethernet interface). It will break some things.