1 iptables -t filter -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
2 iptables -t filter -A INPUT -m state -p tcp --state NEW --dport ssh -j ACCEPT
3 iptables -t filter -A INPUT -m state -p tcp --state RELATED,INVALID -j DROP
4 iptables -t filter -A INPUT -m state -p tcp -j REJECT
5 iptables -t filter -A INPUT -m state -j DROP