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

## rules standard to allow related and established connections
iptables -A INPUT -i lo ACCEPT
iptables -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

## example: ALLOW HTTP FOR given Range 192.168.0.1-255
iptables -A INPUT -p tcp -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -A INPUT -p tcp -m conntrack --ctstate NEW -s 192.168.0.0/24 --dport 80 -j ACCEPT