[Dnsmasq-discuss] IP address based on switch port number (option 82)

[richardvoigt at gmail.com]

On Sun, Feb 14, 2010 at 2:16 PM, Simon Kelley <simon at thekelleys.org.uk> wrote:
> richardvoigt at gmail.com wrote:
>>>
>>> I'm going to have to think about code changes to fix this in the general
>>> case. Are you able to compile and test new versions of dnsmasq?
>>
>> ebtables or iptables can be used to match the source MAC address and
>> only accept inbound DHCP requests from the relay(s).  No change needed
>> to dnsmasq.
>
> I think there's still the problem that a configured host will attempt to
> renew a lease by unicast direct to the DHCP server, so that the request
> never goes to the relay, and doesn't pick up the option-82 information.
> The lack of that information will make dnsmasq think that the existing
> address is not permitted.
>
> A simple fix would be to suppress filtering of dhcp-ranges by tags, but
> only for lease renewals.
>
> Simon.
>

As far as the client knows, the lease was granted by the relay, right?
 So it would unicast to the switch with dhcp-relay capability.