[Dnsmasq-discuss] Using dnsmasq for multiple subnets

[Simon Kelley]

On 07/08/13 18:24, David Cooper wrote:
> Hi all!
>
> Scratching my head here on why this isn't working. I believe I am
> somehow not understanding how the set and tag system works. Hopefully
> someone can point me in the right direction.
>
> Recently I started using a Network Access Control (NAC) system. This
> system provides DHCP for the isolation network. However, I have a need
> to PXE boot but cannot alter the NAC system. Furthermore I have multiple
> imaging servers that service specific subnets.
>
> My solution is to provide one dnsmasq server to point certain subnets to
> the correct imaging server for PXE boot.
>
> I have:
> - setup dnsmasq 2.59 on Ubuntu 12.04 (precise pangolin) LTS on ip
> address 1.1.1.1/16 from the cd-rom repository.
> - added the "ip helper-address 1.1.1.1" on the 2.2.0.0/16 network.
> - For purposes of the example, my imaging server is 3.3.3.3
> - deleted the dnsmasq.conf and replaced it with the following contents.
> 	port=0
> 	log-dhcp
> 	dhcp-boot=pxelinux.0
> 	dhcp-no-override
> 	pxe-prompt="Press F8 for boot menu", 0
> 	dhcp-range=set:site1,2.2.0.0,proxy,255.255.0.0
> 	pxe-service=tag:site1,X86PC, "Boot from blah",pxelinux,3.3.3.3
> 	dhcp-boot=tag:site1,pxelinux.0,site1.net,3.3.3.3
>
> I boot the machine, get the dhcp address from the isolation network, get
> the proxy ip for 1.1.1.1. But it does not go to server 3.3.3.3. for the
> address.
>
> Adjusting the dnsmasq.conf, I remove the set anda tag options and it
> works fine. While this is obviously a solution, when I go to add another
> subnet to the mix I will need to send a different server ip.
>
> I believe the set commands set an identifier. That identifier is used by
> the tag lines to denote when they should act.
>
> What am I doing wrong?
>

I think this is a bug: The code that handles the pxe-proxy is simply 
missinng code to add the tag to the set of tags in use. The fix is 
simple, but it would be good for you to test it, just to make sure I've 
diagnosed the problem.

Would you prefer to test against the current development code, or patch 
2.59?


Cheers,

Simon.