Here it is, it's based it off an example script from the "Iptables Tutorial" v1.1.17 from
http://iptables-tutorial.frozentux.net... I pretty much just copied it in notepad, customized it, copied it to linux and ran it.
## INTERFACES ##
LAN_IP="192.168.5.4"
LAN_BROADCAST_ADDRESS="192.168.5.255"
LAN_IFACE="eth0"
LO_IFACE="lo"
LO_IP="127.0.0.1"
IPTABLES="/sbin/iptables"
## MODULES ##
/sbin/depmod -a
/sbin/modprobe ip_tables
/sbin/modprobe ip_conntrack
/sbin/modprobe iptable_filter
/sbin/modprobe ipt_LOG
/sbin/modprobe ipt_limit
/sbin/modprobe ipt_state
#/sbin/modprobe ipt_owner
#/sbin/modprobe ip_conntrack_ftp
#/sbin/modprobe ip_conntrack_irc
## DEFAULT POLICIES ##
echo "Clearing Tables..."
$IPTABLES -P INPUT DROP
$IPTABLES -P OUTPUT DROP
$IPTABLES -P FORWARD DROP
## CREATE CHAINS ##
$IPTABLES -N bad_tcp_packets
$IPTABLES -N allowed
$IPTABLES -N tcp_packets
$IPTABLES -N udp_packets
$IPTABLES -N icmp_packets
## BAD TCP CHAIN ##
$IPTABLES -A bad_tcp_packets -p tcp --tcp-flags SYN,ACK SYN,ACK \
-m --state NEW -j REJECT --reject-with tcp-reset
$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j LOG \
--log-prefix "New not syn:"
$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j DROP
# ALLOWED CHAIN ##
$IPTABLES -A allowed -p TCP --syn -j ACCEPT
$IPTABLES -A allowed -p TCP -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A allowed -p TCP -j DROP
## TCP RULES ##
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 21 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 113 -j allowed
## UDP RULES ##
#$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 53 -j ACCEPT
## ICMP RULES ##
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 0 -j ACCEPT
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT
#### INPUT CHAIN ####
echo "Creating INPUT Rules..."
## LOCAL ##
$IPTABLES -A INPUT -p tcp -j bad_tcp_packets
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LO_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LAN_IP -j ACCEPT
## INTERNET ##
$IPTABLES -A INPUT -p ALL -d $LAN_IP -m state --state ESTABLISHED,RELATED \
-j ACCEPT
$IPTABLES -A INPUT -p TCP -i $LAN_IFACE -j tcp_packets
$IPTABLES -A INPUT -p UDP -i $LAN_IFACE -j udp_packets
$IPTABLES -A INPUT -p ICMP -i $LAN_IFACE -j icmp_packets
## LOG UNUSUAL PACKETS ##
$IPTABLES -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT INPUT packet died: "
#### OUTPUT CHAIN ####
echo "Creating OUTPUT Rules..."
$IPTABLES -A OUTPUT -p tcp -j bad_tcp_packets
$IPTABLES -A OUTPUT -p ALL -s $LO_IP -j ACCEPT
$IPTABLES -A OUTPUT -p ALL -s $LAN_IP -j ACCEPT
## LOG UNUSUAL PACKETS ##
$IPTABLES -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT OUTPUT packet died: "