[Dnsmasq-discuss] dnsmasq responding to DHCPINFORM only

[Simon Kelley]

Nabeel Jafferali wrote:
> Is it possible to have dnsmasq run alongside an existing DHCP server on the
> network, but only respond to DHCP INFORM requests with the appropriate
> option #. Essentially, I want to have my existing DHCP server hand out IPs,
> but when the client device doesn't receive option 66 information, it send a
> DHCP INFORM request, which I want dnsmasq to reply to.
> 
> 
> I tried to set up dnsmasq.conf to listen on the appropriate interface, did
> not set it as authoritative, did not include any IP address range, but did
> specify dhcp-mac and dhcp-option entries.
> 
>  
> 

If you enable dnsmasq with a dhcp-range that looks something like

dhcp-range=192.168.0.1,static

then it will not hand out leases, but it will reply to DHCPINFORM.

BUT, most clients, once they have a DHCP lease, will unicast DHCPINFORM
requests directly to the DHCP server which supplied the lease, so in
those circumstances dnsmasq would never see the request and therefore
not reply.

Simon.