[Dnsmasq-discuss] specifying dhcp options in proxy mode

Floris Bos bos at je-eigen-domein.nl
Thu May 25 13:19:21 BST 2017

On 05/25/2017 01:30 PM, Simon Kelley wrote:
> On 23/05/17 13:09, Floris Bos wrote:
>> On 05/11/2017 01:36 PM, Simon Kelley wrote:
>>> As stated in the thread you link to, if you're netbooting an OS via PXE
>>> then one the OS starts, it will do DHCP again, and that's the time to
>>> send arbitrary options.
>> Recall some operating systems like FreeBSD do not do DHCP again when net
>> booting, but obtain the cached packet from PXE using the GET_CACHED_INFO
>> PXE call.
> How does this handle the case that the PXE client has received _two_
> packets, one from the DHCP server with an IP address, and one from a PXE
> proxy server with netbbot information. Does GET_CACHED_INFO return one,
> or both, or the combined information from both?

Can specify which packet you want to have. From the PXE spec:


Description: This service returns one of three buffers:
1. The client’s DHCPDISCOVER packet
2. The DHCP server’s DHCPACK packet
3. The Boot Server’s Discover Reply packet, which contains Option #60 
set to “PXEClient”, a
valid boot file name, and may contain MTFTP options

Recall FreeBSD asks for 3.
So yes, I think that in theory it should work if the proxy DHCP packet 
contains the NFS root-path.

The TS did not specify which operating system he is using though.
So don't know if it also works with his.

Yours sincerely,

Floris Bos

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