[Dnsmasq-discuss] bug: trunk DHCP offer/replies being ignored by some devices

Simon Kelley simon at thekelleys.org.uk
Sun Apr 9 21:46:12 BST 2017

On 08/04/17 12:01, Floris Bos wrote:
> On 04/08/2017 12:00 AM, Simon Kelley wrote:
>> But RFC 6842 assures us that no clients are broken by this change :)
>> The options here, as I see it are
>> 1) revert the change and don't support 6842
>> 2) provide a way to disable the client-id reply for broken clients.
>> 3) provide a flag to disable the client-id for all clients.
>> 4) make the new behaviour optional, and provide a flag to enable it.
>> 5) declare it No Our Problem and get the broken clients fixed.
> What about only sending client-id back if chaddr is zeroed?
> Isn't that the corner case 6842 is actually trying to fix?
> ==
>    In some cases, a client may not have a valid hardware address to
>    populate the 'chaddr' field and may set the field to all zeroes. One
>    such example is when DHCP is used to assign an IP address to a mobile
>    phone or a tablet and where the 'chaddr' field is set to zero in DHCP
>    request packets.
> ==

A good suggestion. The bald assertion that DHCP-relays drop packets
without chaddrs in 6842 seems quite dodgy to me, why should they, unless
the chaddr is needed to return the reply to the client?

I'll go offline from here and talk to some DHCP people.......



More information about the Dnsmasq-discuss mailing list