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

[Simon Kelley]

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.