[Dnsmasq-discuss] Any way to force dnsmasq to reply on interface secondary IP ? (Linux)

Jaroslaw Polok Jaroslaw.Polok at cern.ch
Sat Feb 6 06:36:11 GMT 2016


Hello

On 05/02/16 22:55, Simon Kelley wrote:
[...]
>
> Dnsmasq doesn't pay much attention to setting the source address in DHCP
> replies, since for bog-standard DHCP, it's totally ignored. The
> information about where the reply is coming from is carried in fields in
> the DHCP packet. Are you sure that the PXE client is ignoring the reply
> because of the source address field? It may well be, but it's worth
> checking before going any further.

It looks like: I tried identical dnsmasq version and config on a system 
with single IP on its interface and then the client boots as expected.


(I do not know if this is the case for all pxe implementations, but I
observe same problem on two different laptops - Lenovo and Dell - both
set up for UEFI/PXE boot: not much can be seen on screen in the case
of such boot failure - only initial message that it starts IPv4 PXE boot 
.. and then a reset happens after ~ 30 secs timeout..
- in cases of other boot failures these display error message PXE-E??)


> If this is the problem, then a patch
> to set the source address when sending to 4011 would be fairly simple to
> do, but it would be necessary: there's no way to fix this with
> configuration and the existing code.
>

That is what I thought ... (that is in dhcp.c make_fd() I guess?)


> There's no way you could swap primary and secondary addresses on the
> interface?

No, unfortunately that is a very specific setup I cannot change ..


>
>
> Cheers,
>
> Simon.
>

Thanks !

Jarek




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