Configuring The Firewall Using IPTABLES
About the Script:
The script is about to build a firewall in Linux using iptables, the user need only to monitor and respond to simple and easy measures and the script will generate the user specified iptables rule in its form original.
I tested the script to PCLinuxOS, FEDORA-9, DREAM_LINUX, UBUNTU-8.
This is my iptables, version 1.0
About iptables:
Network security is a primary consideration in any decision to host a website as the threats are becoming more widespread and persistent every day. One way to provide additional protection is to invest in a firewall. Although prices are still falling, in some cases, you be able to create a comparable unit using the Linux iptables package on a server for little or no additional cost.
Originally, most firewall / NAT package running on Linux was ipchains, but it had a number of shortcomings. To remedy this situation, Netfilter organization has decided to create a product called iptables.
Starting of the Script
1. Check Iptables Package
2. Iptables Services
3. Build Your Firewall with Iptables
4. Exit
1. Check Iptables Package
Now let the user select the option 1. Check iptable Package from the menu by pressing "1" from the keyboard.
1. Check Iptables Package
2. Iptables Services
3. Build Your Firewall with Iptables
4. Exit
1. Save the iptables
2. Status of Iptables
3. Start iptables Services
4. Stop iptables Services
5. Restart iptable Services
6. Flush iptables (**Use Carefully_it will remove all the rules from iptables**)
7. Go back to Main Menu
target prot opt source destination
REJECT tcp -- 192.168.1.45 172.16.4.8 reject-with icmp-port-unreachable
ACCEPT tcp -- 192.168.1.1 192.168.1.25
LOG icmp -- anywhere anywhere LOG level warning
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
DROP udp -- 192.168.6.3 10.6.3.7
1. Check Iptables Package
2. Iptables Services
3. Build Your Firewall with Iptables
4. Exit
1. INPUT
2. OUTPUT
3. Forward"
2. Firewall using Source Subnet
3. Firewall using for All Source Networks
2. Firewall using Destination Subnet
3. Firewall using for All Destination Networks
2. Block Specific TCP Service
3. Block Specific Port
4. Using no Protocol
1. Accept the Packet
2. Reject the Packet
3. Drop the Packet
4. Create Log
iptables -A INPUT -s 192.168.0.0/24 -d 172.16.0.0/16 -p TCP -j ACCEPT
otherwise 2 for No and the script will return to let the user edit the rule.#!/bin/bash
echo -e "****************Welcome*************"
###############################IPTABLE SERVICES PROGRAM BEGINS HERE###############################
checkstatus()
{
opt_checkstatus=1
while [ $opt_checkstatus != 7 ]
do
clear
#echo -e "\nChoose the Option Bellow!!!\n
echo -e "\n\t*****Note: Save your Iptables before stop/Restart the iptables Services*****\n"
echo -e " 1. Save the iptables\n
2. Status of Iptables\n
3. Start iptables Services\n
4. Stop iptables Services\n
5. Restart iptable Services\n
6. Flush iptables (**Use Carefully_it will remove all the rules from iptables**)\n
7. Go back to Main Menu"
read opt_checkstatus
case $opt_checkstatus in
1) echo -e "*******************************************************\n"
/etc/init.d/iptables save
echo -e "\n*******************************************************\n"
echo -e "Press Enter key to Continue..."
read temp;;
2) echo -e "*******************************************************\n"
/etc/init.d/iptables status
echo -e "*******************************************************"
echo -e "Press Enter key to Continue..."
read temp;;
3) echo -e "*******************************************************\n"
/etc/init.d/iptables start
echo -e "*******************************************************\n"
echo -e "Press Enter key to Continue..."
read temp;;
4) echo -e "*******************************************************\n"
/etc/init.d/iptables stop
echo -e "*******************************************************\n"
echo -e "Press Enter key to Continue..."
read temp;;
5) echo -e "*******************************************************\n"
/etc/init.d/iptables restart
echo -e "*******************************************************\n"
echo -e "Press Enter key to Continue..."
read temp;;
6) iptables -F
echo -e "*******************************************************"
echo -e "All the Rules from the Iptables are Flushed!!!"
echo -e "*******************************************************\n"
echo -e "Press Enter key to Continue..."
read temp;;
7) main;;
*) echo -e "Wrong Option Selected!!!"
esac
done
}
###############################BUILD FIREWALL PROGRAM BEGINS FROM HERE###############################
buildfirewall()
{
###############Getting the Chain############
echo -e "Using Which Chain of Filter Table?\n
1. INPUT
2. OUTPUT
3. Forward"
read opt_ch
case $opt_ch in
1) chain="INPUT" ;;
2) chain="OUTPUT" ;;
3) chain="FORWARD" ;;
*) echo -e "Wrong Option Selected!!!"
esac
#########Getting Source IP Address##########
#Label
echo -e "
1. Firewall using Single Source IP\n
2. Firewall using Source Subnet\n
3. Firewall using for All Source Networks\n"
read opt_ip
case $opt_ip in
1) echo -e "\nPlease Enter the IP Address of the Source"
read ip_source ;;
2) echo -e "\nPlease Enter the Source Subnet (e.g 192.168.10.0/24)"
read ip_source ;;
3) ip_source="0/0" ;;
#4) ip_source = "NULL" ;;
*) echo -e "Wrong Option Selected"
esac
#########Getting Destination IP Address##########
echo -e "
1. Firewall using Single Destination IP\n
2. Firewall using Destination Subnet\n
3. Firewall using for All Destination Networks\n"
read opt_ip
case $opt_ip in
1) echo -e "\nPlease Enter the IP Address of the Destination"
read ip_dest ;;
2) echo -e "\nPlease Enter the Destination Subnet (e.g 192.168.10.0/24)"
read ip_dest ;;
3) ip_dest="0/0" ;;
#4) ip_dest = "NULL" ;;
*) echo -e "Wrong Option Selected"
esac
###############Getting the Protocol#############
echo -e "
1. Block All Traffic of TCP
2. Block Specific TCP Service
3. Block Specific Port
4. Using no Protocol"
read proto_ch
case $proto_ch in
1) proto=TCP ;;
2) echo -e "Enter the TCP Service Name: (CAPITAL LETTERS!!!)"
read proto ;;
3) echo -e "Enter the Port Name: (CAPITAL LETTERS!!!)"
read proto ;;
4) proto="NULL" ;;
*) echo -e "Wrong option Selected!!!"
esac
#############What to do With Rule#############
echo -e "What to do with Rule?
1. Accept the Packet
2. Reject the Packet
3. Drop the Packet
4. Create Log"
read rule_ch
case $rule_ch in
1) rule="ACCEPT" ;;
2) rule="REJECT" ;;
3) rule="DROP" ;;
4) rule="LOG" ;;
esac
###################Generating the Rule####################
echo -e "\n\tPress Enter key to Generate the Complete Rule!!!"
read temp
echo -e "The Generated Rule is \n"
if [ $proto == "NULL" ]; then
echo -e "\niptables -A $chain -s $ip_source -d $ip_dest -j $rule\n"
gen=1
else
echo -e "\niptables -A $chain -s $ip_source -d $ip_dest -p $proto -j $rule\n"
gen=2
fi
echo -e "\n\tDo you want to Enter the Above rule to the IPTABLES? Yes=1 , No=2"
read yesno
if [ $yesno == 1 ] && [ $gen == 1 ]; then
iptables -A $chain -s $ip_source -d $ip_dest -j $rule
else if [ $yesno == 1 ] && [ $gen == 2 ]; then
iptables -A $chain -s $ip_source -d $ip_dest -p $proto -j $rule
else if [ $yesno == 2 ]; then
main
fi
fi
fi
}
main()
{
ROOT_UID=0
if [ $UID == $ROOT_UID ];
then
clear
opt_main=1
while [ $opt_main != 4 ]
do
echo -e "/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\n"
#############Check Whether the iptables installed or not############
echo -e "\t*****Main Menu*****\n
1. Check Iptables Package\n
2. Iptables Services\n
3. Build Your Firewall with Iptables\n
4. Exit"
read opt_main
case $opt_main in
1) echo -e "******************************"
rpm -q iptables
echo -e "******************************" ;;
2) checkstatus ;;
3) buildfirewall ;;
4) exit 0 ;;
*) echo -e "Wrong option Selected!!!"
esac
done
else
echo -e "You Must be the ROOT to Perfom this Task!!!"
fi
}
main
exit 0
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