[Dnsmasq-discuss] dnsmasq responding to DHCPINFORM only

[Nabeel Jafferali]

Thank you, the dhcp-ignore did the trick.

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



On Thu, Dec 29, 2011 at 3:20 PM, Simon Kelley <simon at thekelleys.org.uk>wrote:

> On 29/12/11 16:30, Nabeel Jafferali wrote:
> > Hello.
> >
> > We've recently noticed a problem with our setup, that was based on the
> > information in this (old) thread.
> >
> > Essentially, we used Simon's instructions (below) to configure dnsmasq to
> > not reply to DHCP requests for leases, but to only respond to DHCP INFORM
> > requests. We also had option 66 parameters configued for a specific MAC
> > address range. This worked great in our scenario, where we had devices
> > getting IP/DNS/etc. from the primary DHCP server, and subsequently
> getting
> > DHCP option 66 info from the dnsmasq instance replying to a DHCP INFORM
> > request.
> >
> > However, we've noticed some Windows PCs also request DHCP INFORM, and it
> > appears dnsmasq replies to those requests and provides DNS server
> > information - those PCs then start to use the DNS servers supplied by
> > dnsmasq instead of the DNS servers supplied by the primary DHCP server.
> >
> > A few questions:
> >
> > 1. How can I cause dnsmasq to only reply to DHCP INFORM requests from a
> > certain MAC range? I already have the MAC range configured, and have
> > dnsmasq configured to provide specific option 66 information to that MAC
> > range only.
>
> dhcp-ignore = !<tag> will stop all replies except when the tag is set.
> Use the same tag you set on the MAC range, and it will work fine.
>
> > 2. If not possible, how can I cause DNS server information to not be
> > included in the reply to DHCP INFORM?
>
> dhcp-option = option:dns-server
>
> (Dnsmasq uses itself as the default DNS server, the above overrides the
> default and sets no DNS server option.
>
> > 3. If both not possible, where do I specify the specific DNS servers
> which
> > dnsmasq uses in the aforementioned reply? Perhaps I can just replicate
> the
> > information that the primary DHCP server sends.
> >
>
> Some variation on the example above will work for this.
>
> HTH
>
> Simon.
>
> >
>
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