loop packets out tap0 like an access point
 

I have a bridge (br0) made up of eth0 (local LAN) and tap0 (software that talks to several PLC's).

The problem that I have is that sometimes the PLC's(VERY dumb device) need to send packets to other PLC's... This is done by sending a packet to a piece of software which gives it to tap0.

I am searching for some way to cause the bridge to notice that the packet arriving through tap0 with IP address xxx.xxx.xxx.100 is destined for an IP address (xxx.xxx.xxx.101) and that it is also located on tap0 (destination interface is the same as the arriving) and then go ahead and transmit that packet back to (and through) tap0.

I believe that this is similar to what wireless access points do between two laptops however there is NO wireless interface which means NO HOSTAP... ALSO, as I have seen in other access point articles I believe that I can NOT do a NAT because these PLC's need to be accessible from both sides of br0 and a NAT would cut direct access off from the eth0 side.

It seams to me that there is probably some way to accomplish this with iptables, bit I don't see how.

I know there is probably a standard way to do this so please point out the obvious:D I can take it:cry:

Thanks in advance,

cr13