Firewall rules to allow WAN/internet access from LAN

[eadmaster]

My NanoPi R1 board has 2 ethernet ports, and i'd like to allow the PC connected to the LAN port to have internet access (the WAN port is connected to my ISP router)

With Operwrt i've created these firewall zones to allow this, i am not sure how to do the same in Dietpi:

my current iptables rules:

(ssh) root@DietPi:~/bin# iptables --list-rules

-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-N DOCKER
-N DOCKER-ISOLATION-STAGE-1
-N DOCKER-ISOLATION-STAGE-2
-N DOCKER-USER
-A FORWARD -j DOCKER-USER
-A FORWARD -j DOCKER-ISOLATION-STAGE-1
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A FORWARD -i eth0 -o wlan0 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i wlan0 -o eth0 -j ACCEPT
-A DOCKER-ISOLATION-STAGE-1 -i docker0 ! -o docker0 -j DOCKER-ISOLATION-STAGE-2
-A DOCKER-ISOLATION-STAGE-1 -j RETURN
-A DOCKER-ISOLATION-STAGE-2 -o docker0 -j DROP
-A DOCKER-ISOLATION-STAGE-2 -j RETURN
-A DOCKER-USER -j RETURN

[Joulinar]

Do you need to configure a different IP range on the LAN interface? Or should It be same network segment?

[eadmaster]

i have no particular needs for this, the easier setup will do.

[Joulinar]

Probably some bridged network interfaces would need to be created.

[MichaIng]

These should do:

iptables -t nat -A POSTROUTING -s 192.168.42.0/24 -o eth0 -j MASQUERADE
iptables -A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT
ip6tables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
ip6tables -A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT
ip6tables -A FORWARD -i eth1 -o eth0 -j ACCEPT

This expects the WAN port to be eth0 and the LAN port to be eth1. And a DHCP server or all static IP configs at 192.168.42.0/24 subnet. Otherwise adjust as needed.