[Dnsmasq-discuss] Using dnsmasq for multiple subnets

[David Cooper]

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?

-- 
David R. Cooper
Network Analyst
East Stroudsburg Area School District
Technology Learning Center
2002 Milford Road
East Stroudsburg, PA 18301
http://www.esasd.net
david-cooper at esasd.net
570-424-8500 x1614