Priklad:
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iptables -I INPUT -i eth0 -p tcp -m state --state NEW --source <NEJAKA_IP> --dport <NEJAKY PORT> -j ACCEPT
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#povolit pretrvavajuce spojenia
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
#drop vsetko ine
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT