IPTABLES=/sbin/iptables
$IPTABLES -F
$IPTABLES -F INPUT; $IPTABLES -P INPUT ACCEPT; $IPTABLES -Z INPUT
$IPTABLES -F FORWARD; $IPTABLES -P FORWARD ACCEPT; $IPTABLES -Z FORWARD
$IPTABLES -F OUTPUT; $IPTABLES -P OUTPUT ACCEPT; $IPTABLES -Z OUTPUT
$IPTABLES -X
$IPTABLES -N ALEX-INPUT;
$IPTABLES -N REJECT-PKT;
$IPTABLES -N SYN-FLOOD;
$IPTABLES -A INPUT -j ALEX-INPUT
$IPTABLES -A ALEX-INPUT -i lo -j ACCEPT
$IPTABLES -A ALEX-INPUT -s 127.0.0.0/8 -j DROP
$IPTABLES -A ALEX-INPUT -d 127.0.0.0/8 -j DROP
$IPTABLES -A ALEX-INPUT -s 111.222.111.222 -j DROP
$IPTABLES -A ALEX-INPUT -p tcp -m tcp ! --syn -m state --state NEW -j DROP
$IPTABLES -A ALEX-INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
$IPTABLES -A ALEX-INPUT -p icmp -m icmp --icmp-type ping -j ACCEPT
$IPTABLES -A ALEX-INPUT -p tcp -m tcp --dport 12444 -j ACCEPT
$IPTABLES -A ALEX-INPUT -p tcp -m tcp --dport 12555 -j ACCEPT
$IPTABLES -A ALEX-INPUT -p tcp -m tcp --dport 12666 -j ACCEPT
$IPTABLES -A ALEX-INPUT -p udp -m udp --dport 5060 -j ACCEPT
$IPTABLES -A ALEX-INPUT -p udp -m udp --dport 5061 -j ACCEPT
$IPTABLES -A ALEX-INPUT -p udp -m udp --dport 10000:20000 -j ACCEPT
$IPTABLES -A ALEX-INPUT -j REJECT-PKT
$IPTABLES -A REJECT-PKT -p tcp -m tcp -j REJECT --reject-with tcp-reset
$IPTABLES -A REJECT-PKT -p udp -m udp -j REJECT --reject-with icmp-port-unreachable
$IPTABLES -A REJECT-PKT -p icmp -m icmp --icmp-type ping -j REJECT --reject-with icmp-host-unreachable