[Dnsmasq-discuss] DHCP over a wireless bridge

[John Kaye]

Hi All,

I'm developing a transparent wireless bridge for a client who 
manufactures printers. The printers connect through the Ethernet side of 
the bridge and the wireless side of the bridge associates with an AP.

The AP will reject frames from the printers because their source address 
is different from the source address that is associated with the AP; to 
resolve that, ebtables is used to snat the source address of the frames 
from the printers, and everything flows.

Everything flows nicely when the printers are configured with static 
IPs. When the printers are configured to use DHCP, the AP never delivers 
an IP, even though it receives a discovery request from the printers. I 
assume the AP doesn't respond because the DCHP DISCOVER frame has the 
client mac address encoded within it, which doesn't match the address 
that it is associated with, so it's ignored. Does that sound correct?

To enable the printers to get IP addresses from the AP, it would seem 
that a DHCP relay proxy of some sort would need be to implemented to run 
on the bridge. The proxy would relay DHCP requests to the AP and return 
addresses to the printers. Does that sounds feasible?

If my assumptions are correct, can dnsmasq be configured as a DHCP relay 
proxy? If so, are there examples of how it can be done?

If my assumptions are not correct (which I imagine they are),  are there 
other options?

I truly appreciate any guidance. My networking knowledge is limited, 
though it is growing by leaps and bounds!

Cheers,
-John