Its a start :-)

iptables_rules.sh

# Allow outgoing traffic and disallow any passthroughs
iptables -P INPUT DROP
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP

# Allow traffic already established to continue
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

# Allow ssh, web services
iptables -A INPUT -p tcp --dport ssh -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j ACCEPT


# Allow local loopback services and internal network
iptables -A INPUT -i lo -j ACCEPT

# Allow pings
iptables -I INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT
iptables -I INPUT -p icmp --icmp-type source-quench -j ACCEPT
iptables -I INPUT -p icmp --icmp-type time-exceeded -j ACCEPT