IPTABLE script

iptabler.sh

#!/bin/bash
####################################
####                            ####
####    2012 Ttech              ####
####    Bash Router Enabler     ####
####                            ####
####################################


# this should be the only part you need to modify
# the rest is fuly automated

# internal and external ip addresses
internal="127.0.0.1"
external="127.0.0.1"

# ports to open
tcp=(80 44 322 21 25 6667);
udp=(2532 56454)


# Do we want to clear iptables? Perhaps?
echo -n "Do you want to clear iptables? [y/n]"
read -n 1 clear_tables
if [ "$clear_tables" == "n" ]; then
	echo -e "\n[ WARN ] no deletion may cause issues\n[NOTICE] iptables not being cleared"
else 	
	echo -e "\n[NOTICE] iptables attempting to be cleared"
	iptables -L
	iptables -X
fi

# Do we want o learn about kernel modules? YEA!
kernel_modules=("ip_tables" "iptables_nat" "nf_conntrack" "nf_contrack_ftp" "nf_nat_ftp" "nf_contrack_irc");
for module in "${kernel_modules[@]}"
do
	#modprobe ${module}
	if [ $? -eq 0 ]; then
		echo -e "[NOTICE] Loading Kernel Module \"${module}\""
	else
		echo -e "[FATAL] Could not load ${module} entering failed state"
		exit 1
	fi
done

# Setting IP Fowarding and routing

echo -e "[STATUS] Setting routing enabled"
# enable ip forwarding ( so we can act as a router )
echo "1" > /proc/sys/net/ipv4/ip_forward
# set some awesome dynaddress stuff
echo "1" > /proc/sys/net/ipv4/ip_dynaddr

echo -e "[STATUS] Done Loading Kernel Modules"

# We need to load the stuff to make iptables work more like a router
echo -E "[NOTICE] Setting default firewall rules"
iptables -P INPUT DROP
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP
true
if [ $? -eq 0 ]; then
	echo "[STATUS] Finished setting default rules"
else 
	echo "[FATAL] Could not set default rules"
	exit 1
fi

iptables -A FORWARD -i "$external" -o "$internal" -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -i "$internal" -o "$external" -j ACCEPT
iptables -A FORWARD -j LOG
true
if [ $? -eq 0 ]; then
        echo "[STATUS] Finished setting routing rules"
else
        echo "[FATAL] Could not set routing rules"
	exit 1
fi


# load tcp ports into iptables
for port in "${tcp[@]}"
do
    iptables -A INPUT -p tcp --dport ${port} -j ACCEPT
	case $? in
	0) echo "[NOTICE] Sucessfully adding tcp port ${port}"
	;;
        1) echo "[FATAL] Could add tcp port ${port} to iptables"
	;;
	126) echo "[FATAL] Permission problem or command is not an executable"
	     exit 1
	;;
	127) echo "[FATAL] No such command"
	     exit 1
	;;
	128) echo "[WHAT] Invalid Argument"
 	esac
done

# load udp ports into iptables
for port in "${udp[@]}"
do
        iptables -A INPUT -p tcp --dport ${port} -j ACCEPT
        case $? in
        0) echo "[NOTICE] Sucessfully adding udp port ${port}"
        ;;
        1) echo "[FATAL] Could add udp port ${port} to iptables"
        ;;
        126) echo "[FATAL] Permission problem or command is not an executable"
             exit 1
        ;;
        127) echo "[FATAL] No such command"
             exit 1
        ;;
        128) echo "[WHAT] Invalid Argument"
        esac
done

echo -e "[STATUS] Done Loading ipTables"

echo -e "\n\n**********************************************************\n\n\n\t\tFINISHED. ROUTER ENABLED....\n\n"