LinuxQuestions.org - Iptables Critique

I've tried putting a firewall script together based on the tutorials I've read around the internet. Please critique and give me any recommendations especially for a stronger firewall. Thanks!
Code:
#!/bin/sh



#############################################################

# Configuration

#############################################################



        # Load Modules

        /sbin/depmod -a



        # Required modules

        /sbin/modprobe ip_conntrack

        /sbin/modprobe ip_tables

        /sbin/modprobe iptable_filter

        /sbin/modprobe iptable_mangle

        /sbin/modprobe iptable_nat

        /sbin/modprobe ipt_LOG

        /sbin/modprobe ipt_limit

        /sbin/modprobe ipt_MASQUERADE



        # Non-Required modules

        #/sbin/modprobe ipt_owner

        #/sbin/modprobe ipt_REJECT

        #/sbin/modprobe ip_conntrack_ftp

        #/sbin/modprobe ip_conntrack_irc

        #/sbin/modprobe ip_nat_ftp

        #/sbin/modprobe ip_nat_irc



#############################################################

# Local Settings

#############################################################



        # IPTables Location

        IPTABLES="/sbin/iptables"

        

        # External Interface

        EXT="eth0"



        # Internal Interface

        INT="eth1"

        LOCAL_IP="192.168.1.1"

        LOCAL_BCAST="192.168.1.255"



        # Loopback Interface

        LBACK="lo"

        LBACK_IP="127.0.0.1"



        # Internal Network Configuration

        LAN_IP="192.168.1.0/24"



#############################################################

# Firewall Configuration                                                                                  

#############################################################



        # Default Policy

        $IPTABLES -P INPUT        DROP

        $IPTABLES -P OUTPUT        DROP

        $IPTABLES -P FORWARD        DROP



        # User-Specified Chains

        $IPTABLES -N bad_packets

        $IPTABLES -N tcp_packets

        $IPTABLES -N udp_packets

        $IPTABLES -N icmp_packets



        # Flush ALL chains

        $IPTABLES -F INPUT

        $IPTABLES -F OUTPUT

        $IPTABLES -F FORWARD

        $IPTABLES -t nat -F

        $IPTABLES -t mangle -F



        $IPTABLES -F bad_packets

        $IPTABLES -F tcp_packets

        $IPTABLES -F udp_packets

        $IPTABLES -F icmp_packets



#############################################################

# Chains - User Specified

#############################################################



# bad_packets

$IPTABLES -A bad_packets -p tcp --tcp-flags SYN,ACK, SYN,ACK -m state --state NEW -j REJECT --reject-with tcp-reset



$IPTABLES -A bad_packets -p tcp ! --syn -m state --new -j LOG --log-prefix "New not syn:"



$IPTABLES -A bad_packets -p tcp ! --syn -m state --new -j DROP



# tcp_packets





# udp_packets



# Blocks Microsoft Network Broadcasts

$IPTABLES -A udp_packets -p UDP -i $EXT --destination-port 135:139 -j DROP



# Blocks DHCP requests from outside of network.

$IPTABLES -A udp_packets -p UDP -i $EXT -d 255.255.255.255 --destination-port 67:68 -j DROP



# icmp_packets



# Allows Echo request

$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT



# Allows TTL equals 0 during transit / reassembly

$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT



#############################################################

# Chains - INPUT 

#############################################################



# Filters packets through bad_packets chain

$IPTABLES -A INPUT -p ALL -j bad_packets



# Only except packets that are established or related

$IPTABLES -A INPUT -p ALL -i $EXT -m state --state ESTABLISHED,RELATED -j ACCEPT



# Drops MS multicasts

$IPTABLES -A INPUT -i $EXT -d 224.0.0.0/8 -j DROP



# Drops attempts from outsider acting like they are on the LAN

$IPTABLES -A INPUT -i $EXT -s $LAN_IP -j DROP



# Disperse protocol types on specific chains

$IPTABLES -A INPUT -p TCP -i $EXT -j tcp_packets

$IPTABLES -A INPUT -p UDP -i $EXT -j udp_packets

$IPTABLES -A INPUT -p ICMP        -i $EXT -j icmp_packets





#############################################################

# Chains - OUTPUT

#############################################################



#Allows traffic out of the firewall

$IPTABLES -A OUTPUT -p ALL -s $LOCAL_IP -j ACCEPT

$IPTABLES -A OUTPUT -p ALL -s $LAN_IP -j ACCEPT

$IPTABLES -A OUTPUT -p ALL -o $EXT -j ACCEPT



#############################################################

# Chains - FORWARD

#############################################################



# Filters packets through bad_packets chain

$IPTABLES -A FORWARD -p ALL -j bad_packets



# Drops MS multicasts

$IPTABLES -A FORWARD-d 224.0.0.0/8 -j DROP



# Drops attempts from outsider acting like they are on the LAN

$IPTABLES -A FORWARD -s $LAN_IP -j DROP



# Disperse protocol types on specific chains

$IPTABLES -A FORWARD -p TCP -j tcp_packets

$IPTABLES -A FORWARD -p UDP -j udp_packets

$IPTABLES -A FORWARD -p ICMP -j icmp_packets



#############################################################

# Table - NAT

#############################################################



#NATing for the internal LAN

$IPTABLES -t nat -A POSTROUTING -o $EXT -j MASQUERADE



#############################################################

# Table - MANGLE

#############################################################



#############################################################



# Enables forwarding of interfaces

echo "1" > /proc/sys/net/ipv4/ip_forward