-P INPUT DROP
-P FORWARD DROP
-P OUTPUT DROP
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -d 224.0.0.251/32 -p udp -m udp --dport 5353 -j ACCEPT
-A OUTPUT -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT
-A OUTPUT -o lo -j ACCEPT