[Dnsmasq-discuss] specifying dhcp options in proxy mode

Andriy Gapon avg at FreeBSD.org
Thu May 25 15:14:29 BST 2017

On 25/05/2017 14:29, Simon Kelley wrote:
> On 23/05/17 07:05, Andriy Gapon wrote:
>> On 23/05/2017 01:14, Simon Kelley wrote:
>>> To the best of my knowledge it's _only_ PXE clients which can accept
>>> extra options from a proxy. PXE is a superset of DHCP, which includes
>>> that functionality. The DHCP clients run by the OS are just that - DHCP
>>> clients, they don't know how to do the PXE proxy-server tricks.
>> It seems that the discussion went into a direction that I didn't expect.
>> Let me try to make it simpler (for me) again.
>> So, should dnsmasq in the DHCP proxy mode be able to send a root-path option?
> No it can't. It's deliberate that it can't and the reasoning for that is
> that packets sent in proxy mode can only go to a PXE client, which
> doesn't know what to do with (eg) a root-path option.

As an example, iPXE does know what to do with root-path in certain cases:

As an aside, as far as I can see, iPXE never contacts the proxy server on the
proxy port.  It takes all information it needs from the proxy's DHCP offer
packet and does not perform any further communication with it.

> If that reasoning is shown to be incorrect, it would be relatively
> simple to change the code to allow arbitrary options.

Andriy Gapon

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