This is a weird one.
I need to be able to send a UDP packet to the broadcast address of the LAN subnet from accross the pepvpn link.
We are using one-to-one NAT now to send to specific IPs - that works great.
And we are using that in most cases in place of broadcast. i.e. we send to UDP port 3520 at each of the 6 or 7 POS stations instead of to port 3520 at the broadcast address in order to have the callerid pop on them all.
but I have run into a POS system that will ONLY respond if the packet was to the broadcast!
really annoying. Could one-to-one NAT mapping have an option to allow one IP/port combo to be mapped to the broadcast? i.e.
real subnet is 192.168.3.0
subnet 10.200.100.0 is mapped to it
Address 192.168.3.254 is NOT IN USE on the subnet
so 10.200.100.254 is mapped to the 192.168.3.255 broadcast address.
Seems like something like this is the only way to accomplish this, since you cannot normally route the broadcast over routed links.
Another way to look at this is a more complete nat translation - on Sonicwalls you can do a NAT translation and select:
Source IP
Translated source IP
destination IP
translated destination IP
destination port
translated destination port
so - when there is a sonicwall between us and the POS we can do:
Source IP {our callerid server}
Translated IP {the LAN interface IP} (so that the broadcast will seem to come form something on the local network)
destination IP {the WAN IP of the sonicwall}
translated destination IP {the LAN broadcast address}
original and destination port 3520 (callerid)
end result - we send a packet to the WAN port of the sonicwall over the VPN, and the sonicwall echos it to the LAN broadcast. Works great.
I know this is an odd one, but we have a large group of customers coming on who need this feature.