Iptables sample in centos

iptables -t nat -A POSTROUTING -j MASQUERADE
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -p udp --dport 443 -j ACCEPT
iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -m state --state NEW -m udp -p udp --dport 443 -j ACCEPT
iptables -t nat -A POSTROUTING -s 20.30.0.0/24 -o eth0 -j MASQUERADE
iptables -A FORWARD -s 20.30.0.0/24 -j ACCEPT
iptables -A INPUT -i eth0 -m state --state NEW -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -i eth0 -m state --state NEW -p udp --dport 443 -j ACCEPT
service iptables save
service iptables restart
service iptables stop
service iptables start