Bridge with NAT reflection.

RouterOS Beginner Basics
1

We have an RB450G with rOS 5.14 sitting between our 24-port switch and the wireless connection to the next building where we have another RB450G acting as our internet gateway and firewall. The switch is on Ether5 and the wireless connection is on Ether4 and the two are ports on bridge1. In order to facilitate communications between the buildings, Ether4 and Ether5 MUST be bridged.

But, we have 2 things we want to do.

  1. Add PCQs to load balance all traffic going over the wireless link. (I think I can figure that one out.)
  2. Internally NAT our external public IP addresses to their internal counterparts.

For example, we have an external address block of 69.165.166.32/28 but an internal IP address block of 172.16.0.0/16. 69.165.166.34 is public IP address of the gateway router in the other building. 69.165.166.33 is our ISP. Everything between 69.165.166.35 and 69.165.166.46 is our various servers.

The problem is, if I, going from 172.16.100.124, want to connect to 69.165.166.46, it has to go through our network, over our wireless link to the next building, out our gateway, be NATed by our ISP, and reflected back to us, before it can reach the server. I got the RB450G to eliminate this problem. I’d like the RB450G to do the Dst-NAT and reflection instead. The thing is, I can’t figure out how to do it because of the bridge.

Could someone help me with this?

Thanks

2

Both should be possible by enabling “use IP firewall” in the bridge settings. This will make the bridged packets be processed by the firewall as well. I’m not sure how well it will work with NAT, but I’ve used it with mangle before to setup QoS on a limited basis.

3

Did as you said and set “Use IP Firewall” to the bridge settings.

Added the NAT below as well.
/ip firewall nat print
0 chain=dstnat action=netmap to-addresses=172.16.2.2 dst-address=69.165.166.46
Still not working.