Hi,

I have an old RB433 I would like to use it to just capture packets in between my wan connection on an sd card.
Can someone help me in a config that would work as in my setup below:

WAN ------> ETH0 (RB433) ETH1-----> ROUTER B ---------> LAN

Transparent bridge should do it. Start with blank config, create bridge, add two ports and you're almost there. Then decide how you're going to connect to the device,serial port, third ethernet, even the first two could be used, but it would require additional config elsewhere.