[Dnsmasq-discuss] PXE service across subnets

[Simon Kelley]

On 03/12/10 22:35, GARRISON, TRAVIS J. wrote:
>>> We have tried searching but we could not find an answer to our
>>> problem. Our clients cannot pxe boot from our dnsmasq server
>>> across different subnets. We have the dnsmasq server configured
>>> to proxy the dhcp requests to our main dhcp server. We have
>>> created helper addresses for both the dhcp and pxe server on the
>>> different subnets. Pxe booting works fine when on the same
>>> network. What are we missing?
>>>
>>
>> Is anything logged by dnsmasq? The DHCP helper function needs to
>> relay broadcasts to both servers. Are you sure that the switches
>> can do that?
>
> We did a packet capture on the dnsmasq server and tried to pxe boot
> one of our clients. We can see 3 DHCP Discover requests come in from
> the 172.25.16.0 subnet, which would be our client, but we see no
> response from the dnsmasq server. We have the option
> dhcp-range=172.25.16.0,proxy set. Our networks are in the
> 255.255.252.0 subnet range, would that have any problems?
>

Ah, lightbulb. This extract from the man page is relevant:

"For  directly connected  networks  (ie,  networks  on  which the 
machine running dnsmasq has an interface) the netmask is optional. It 
is, however, required for networks which receive DHCP service via a 
relay agent."

So your dhcp-range line should be

dhcp-range=172.25.16.0,proxy,255.255.252.0


Try that.

Simon.