iptables.sh

iptables -P FORWARD DROP                                          # we aren't a router
iptables -A INPUT -m state --state INVALID -j DROP                # drop bad packets
iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT  # allow current connections
iptables -A INPUT -i lo -j ACCEPT                                 # allow lo interface
iptables -A INPUT -s 1.2.3.4 -j ACCEPT                            # allow whom-ever ya want
iptables -P INPUT DROP                                            # drop the rest