I have the following simple situation: two internet connections via two distinct ethernet NICs, eth0 and eth1, and two APs (I use hostapd, of course) on two distinct wireless cards, wlan0 and wlan1. The two wifi cards have different subnets (192.168.53.0/24, 10.0.15.0/24), and the two ethernet cards are on different subnets (192.168.1.0/24, 10.10.2.0/24).
I would like to keep forwarding completely separate, in other words:
wlan0 --> eth0 wlan1 --> eth1
I know how to bind applications to different interfaces, and how to use policy routing. What I do not know is whether I can use iptables to forward as above, or I absolutely need to use Policy Routing to achieve this.