# base case
iptables -P FORWARD DROP
iptables -A FORWARD -m state --state INVALID -j DROP
- iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
+ iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
# allow
iptables -A FORWARD -i br0 -o br0 -j ACCEPT