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

[Simon Kelley]

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.



Cheers,

Simon.