[Dnsmasq-discuss] Environment variable DNSMASQ_CLIENT_ID

[Simon Kelley]

On 05/12/2021 08:21, Community Member via Dnsmasq-discuss wrote:
> Follow up from "RaspberryPi PCAP file" thread.
> 
> On Sat, Dec 4, 2021 at 1:42 PM Geert Stappers wrote:
>> On Sat, Dec 04, 2021 at 12:11:13PM -0800, Carl Karsten wrote:
>>> On Sat, Dec 4, 2021 at 10:12 AM Geert Stappers wrote:
>>>>
>>>> My observation on the PCAP file
>>>> * there are several stages
>>>> * each stage starts with a (partial) DHCP session
>>>>
>>>>
>>>> The first stage:
>>>> * DHCP Discover with option 97, Client Identifier,
>>>>   f6 27 6d 7a f6 27 6d 7a f6 27 6d 7a f6 27 6d 7a
>>>>   from client
>>>> * DHCP Offer with filename 'ipxe/undionly.kpxe'
>>>>   from server
>   .....
>>>> The second stage:
>>>> * DHCP Discover with option 97, Client Identifier,
>>>>   f6 27 6d 7a f6 27 6d 7a f6 27 6d 7a f6 27 6d 7a
>>>>   from client  (yes, that is the same identifier)
>>>> * DHCP Offer with filename 'ipxe/undionly.kpxe'
>>>>   from server (yes, that is the same filename)
>   .....
>>>
>>> My pi netboot needs are basically satisfied,
>>
>> OK
>>
>> And what about the dnsmasq needs that did get us here???
>>
> 
> Hmm.. I'm not out of the weeds just yet.
> 
>>>> The first stage:
>>>> * DHCP Discover with option 97, Client Identifier,
>>>>   f6 27 6d 7a f6 27 6d 7a f6 27 6d 7a f6 27 6d 7a
> 
> I need access to that value.  That's the serial number  f6 27 6d 7a
> repeated 4 times.
> but not
> DNSMASQ_CLIENT_ID=01:b8:27:eb:6d:27:f6

The DHCP client identifier is option 61 and that's what ending up in the
DNSMASQ_CLIENT_ID variable. Option 97 is a PXE thing, it's normally
called the UUID in the PXE documentation.

Simon.