*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT DROP [0:0]
#allow all loopback traffic
-A INPUT -i lo -j ACCEPT
# no incoming connections
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
# allow ping etc.
-A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT
-A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT
-A INPUT -p icmp --icmp-type echo-request -j ACCEPT
# allow incoming ping
-A INPUT -p icmp --icmp-type echo-request -j ACCEPT
-A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
# allow outgoing DNS
-A OUTPUT -p udp --dport 53 -j ACCEPT
-A INPUT -p udp --sport 53 -j ACCEPT
COMMIT