*filter section - forwarding

# Forwarding rules

# forward packets along established/related connections

-A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

# forward from LAN (p1p1) to WAN (p4p1)

-A FORWARD -i p1p1 -o p4p1 -j ACCEPT

# drop all other forwarded traffic

-A FORWARD -j DROP

COMMIT