Transparent Filtering Router - MAC NAT?

RouterOS General
1

I have a RB1000 running RouterOS 3.3

I need to connect Eth1 to the “wild” (i.e. the enterprise network 10.11.12.0/24)

Eth2, Eth3, and Eth4 will be connected to devices that need protection from the wild, but still need to be on the 10.11.12.0/24 network.

In addition, the traffic coming from Eth2, 3, and 4 to the wild needs to appear to come from a single MAC address.

I can satisfy the first part easily by creating a bridge and building firewall rules. The hard part seems to be the MAC part. I’ve seen references here to MAC-NAT, ARP Proxy, ARP-NAT, Masquerading, etc. Nothing I’ve tried seems to work.

I would be grateful for any suggestions.

2

You may set router to be NAT. Then it will present himself as request of all connections (meaning, only his outside interface MAC is visible to the outside network).

Side effect is that everything behind that NAT will became hiden form outside network, so if you need some connections you have to set port mapping.