iptablesの設定

iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT DROP

iptables -A INPUT -m state --state RELATED, ESTABLISHED -j ACCEPT
iptables -A OUTPUT -m state --state NEW, RELATED, ESTABLISHED -j ACCEPT
iptables -A INPUT -i lo -j ACCEPT

mkdir /etc/iptables
iptables-save > /etc/iptables/rule.cfg
echo "pre-up iptables-restore < /etc/iptables/rule.cfg" >> /etc/network/interfaces