[Dnsmasq-discuss] Does the --interface option to dnsmasq also apply to incoming broadcast DHCP requests?

[Chris Friesen]

Hi,

I was just wondering whether the --interface and --except-interface 
options to dnsmasq would also apply to messages like DHCPDISCOVER and 
DHCPREQUEST which are broadcast to 255.255.255.255.

In my particular case I have an existing dnsmasq instance that is 
running, and I want to add a second dnsmasq instance to handle DHCP 
requests coming from a specific subset of interfaces.   I don't want the 
primary dnsmasq instance to see the requests coming in on those 
interfaces, and I don't want the second dnsmasq instance to see requests 
coming in on the other interfaces.

As a concrete example, suppose I have network interfaces eth0/eth1/eth2 
and I have instance A of dnsmasq which is run as "dnsmasq 
--except-interface eth2", and instance B of dnsmasq which is run as 
"dnsmasq --interface eth2 --except-interface lo".

If a broadcast DHCPDISCOVER or DHCPREQUEST comes in on eth0/eth1 which 
dnsmasq instance(s) will see it?

If a broadcast DHCPDISCOVER or DHCPREQUEST comes in on eth2 which 
dnsmasq instance(s) will see it?

If a broadcast DHCPDISCOVER or DHCPREQUEST is emitted by an entity on 
the local host which dnsmasq instance(s) will see it?

Thanks,

Chris Friesen