[Dnsmasq-discuss] Reg: Info related to leases file

[Simon Kelley]

On 24/09/13 13:01, Vladislav Grishenko wrote:
>> Out of the three types:  DUID-LLT, DUID-EN and DUID-LL, which one is used
>> by dnsmasq? I am asking because I want to confirm whether the MAC
>> address of the network interface is always a substring of the client DUID
> or
>> not.
>
> 1. DUID-EN, if --dhcp-duid specified
> 2. DUID-LL from MAC of the first suitable interface, if HAVE_BROKEN_RTC
> defined
> 3. DUID-LLT from MAC of the first suitable interface for all other cases
>
> FYI, as per RFC3315 DUIDs should be treated as opaque values only:
>> 9. DHCP Unique Identifier (DUID)
>> Clients and servers MUST treat DUIDs as opaque values and MUST only
>> compare DUIDs for equality.  Clients and servers MUST NOT in any
>> other way interpret DUIDs.
>

Vladislav's reply is correct for the server DUID. I think the original 
question was about the client DUIDs. The type of these is decided by the 
client, not by dnsmasq, so they are of even less use.

However, if you're interested in the MAC addresses of clients, the very 
latest dnsmasq code can determine that in most cases. The MAC address is 
not stored in the leases file, but it can be used to key configurations 
to particular MAC addresses, and it's made available to the DHCP lease 
external script, so an external application can use it.

The latest code in the git repo has this facility.

Cheers,

Simon.