[Dnsmasq-discuss] dnsmasq responding to DHCPINFORM only

Nabeel Jafferali nabeel at jazinga.com
Wed Aug 18 22:30:28 BST 2010

Thank you Simon. That worked perfectly, I have the client devices getting
their boot parameters from dnsmasq but still getting their IP addresses from
the primary DHCP server (a Linksys router, in my test case).

Nabeel Jafferali
Director - Product Mgmt.
Jazinga Inc.
416.548.4755 x103

-----Original Message-----
From: dnsmasq-discuss-bounces at lists.thekelleys.org.uk
[mailto:dnsmasq-discuss-bounces at lists.thekelleys.org.uk] On Behalf Of Simon
Sent: August-18-10 5:19 PM
To: dnsmasq discussion list
Subject: Re: [Dnsmasq-discuss] dnsmasq responding to DHCPINFORM only

Nabeel Jafferali wrote:
> Is it possible to have dnsmasq run alongside an existing DHCP server on
> network, but only respond to DHCP INFORM requests with the appropriate
> option #. Essentially, I want to have my existing DHCP server hand out
> but when the client device doesn't receive option 66 information, it send
> 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


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.


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