[Dnsmasq-discuss] Serving Addresses on Multiple Subnets

Simon Kelley simon at thekelleys.org.uk
Thu Feb 7 15:35:50 GMT 2013


On 07/02/13 15:25, John Stowers wrote:
> Hi All,
> 
> I have read quite a bit of old postings on this, and have not been able
> to make this work. Some help would be appreciated.
> 
> Our lab does multiple camera tracking using ethernet camers. Each
> computer has 4-8 cameras connected (via a POE switch) to
> a camera.
> 
> Currently I manually assign to a private subnet, one camera and one port
> of each card.
> 
> I would like to move to a system where I can assign these cameras via DHCP.
> 
> This is the current setup.
> 
> I have a debian machine running dnsmasq acting as a gateway.
> eth0 connects to the internet
> eth1 connects to the local 192.168.1.X network
> 
> On the local network are the tracking machines; many machines with the
> following configuration
> eth0 gets 192.168.1.X
> eth1 192.168.21.1
> eth2 192.168.22.1
> eth3 192.168.23.1
> 
> etc. and cameras
> 
> 192.168.21.2
> 192.168.22.2
> 192.168.23.2
> 
> etc.
> 
> I cannot seem to configure dnsmasq to hand out addresses on anything
> other than 192.168.1.X. Here is the relevant parts of the dnsmasq
> configuration. Can anyone help?
> 
> #(192.168.88.X is like the 192.168.2X.X ones above)
> 
> #this line works as expected,
> dhcp-range=interface:eth1,set:lan,192.168.1.100,192.168.1.255,255.255.255.0,2h
> 
> #if only this line is present then the 88.1 address never gets handed out
> #no address range available for DHCP request via eth1
> dhcp-range=interface:eth1,set:lan,192.168.88.1,static
> 
> dhcp-host=00:1e:8c:3d:ae:a6,set:lan,192.168.88.1
> 
> Regards,
> 

I'm not clear from your description, but I think you're trying to do
DHCP on networks which are remote from the machine running dnsmasq: The
192.168.21.x etc networks have an interface on the tracking machine, and
the camera, but not the Debian machine.?

In that case you need to run a DHCP relay on each tracking machine,
which will collect the DHCP requests from the camera and forward them to
the Debian box.

Something like dhcp-helper or ISC DHCP relay would be fine.

Simon.




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