Permitindo que firewall e rede estabeleçam conexão com outras máquinas

iptables -A INPUT -p ! icmp -m state --state ESTABLISHED -j ACCEPT

iptables -A FORWARD -s 192.168.0.0/24 -p ! icmp -m state --state NEW,ESTABLISHED -j ACCEPT

iptables -A FORWARD -d 192.168.0.0/24 -p ! icmp -m state --state ESTABLISHED -j ACCEPT

iptables -A OUTPUT -p ! icmp -m state --state NEW,ESTABLISHED -j ACCEPT