[Dnsmasq-discuss] dnsmasq with dhcpv6 and dhcp-host option

[Sheng Yang]

On Mon, Jan 14, 2013 at 1:13 PM, Simon Kelley <simon at thekelleys.org.uk> wrote:
> On 14/01/13 18:48, Sheng Yang wrote:
>
>> Another question: Could it possible to use dhcp-host with ipv6 and id:*?
>>
>> like this:
>>
>> dhcp-host=06:6f:aa:00:00:2d,id:\*,[fc00:1234:5678:1234::144],fred,infinte
>>
>> I found seems it doesn't work, but I found these lines in dnsmasq.conf:
>>
>> <quote>
>>
>> A single dhcp-host may contain an IPv4 address or an IPv6 address, or
>> both. IPv6 addresses must be bracketed by square brackets thus:
>> --dhcp-host=laptop,[1234::56] Note that in IPv6 DHCP, the hardware
>> address is not normally available, so a client must be identified by
>> client-id (called client DUID in IPv6-land) or hostname.
>>
>> The special option id:* means "ignore any client-id and use MAC
>> addresses only." This is useful when a client presents a client-id
>> sometimes but not others.
>> </quote>
>>
>> Does this means dnsmasq is able to extract MAC from DUID, then
>> identify the client?
>
>
> Sadly, no. The DUID can't be reliably used to find the MAC. (A client with
> more than one network interface will use the same DUID on all interfaces,
> and it won't change if the network card is swapped-out, for instance)
>
> The standards people have decided that having access to the MAC address
> would be a good idea, after all, so a new DHCPv6 is being defined. When
> that's done, dnsmasq will support it, but at the moment it's not possible,
> sorry.

Simon, thank you for clarifying!

I think let dhcp client generate DUID-LL should be a good idea in this
case, sadly most of them would generate DUID-LLT by default...

--Sheng
>
>
>
> Cheers,
>
> Simon.
>
>
>