Port Restricted Cone NAT configure by Linux IPTables

PRC (Port Restricted Cone) NAT,  how to configure by Linux IPTables

PRC NAT: An internal address (iAddr:iPort) is mapped to an external address (eAddr:ePort), any packets from iAddr:iPort will be sent through eAddr:ePort

Hardware: PC with double LAN card.

OS: Red HAT/CentOS

Interface:

eth0: Private IP block                                                   //Configure eth0 with Private IP

eth1: Public IP                                                              // Configure eth1 with Public IP

#vi PRCNAT.sh                                                            //Firewall script

#!/bin/bash

IPTABLES=/sbin/iptables

MODPROBE=/sbin/modprobe

INT_NET1=192.168.5.0/24

INT_IF=eth1

EXT_IF=eth0

###Flush existing rules and set chain policy setting to DROP

echo "[+] Flushing existing iptables rules..."

$IPTABLES -F

$IPTABLES -X

$IPTABLES -F -t nat

$IPTABLES -t nat -X

$IPTABLES -t mangle -X

$IPTABLES -t mangle -F

$IPTABLES -P INPUT ACCEPT

$IPTABLES -P OUTPUT ACCEPT

$IPTABLES -P FORWARD ACCEPT

###### NAT rules ######

echo "[+] Setting up NAT rules..."

$IPTABLES -t nat -A POSTROUTING -s $INT_NET1 -o $EXT_IF -j MASQUERADE

###### forwarding ######

echo "[+] Enabling IP forwarding..."

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

####Saving iptables rule#######

service iptables save

service iptables restart

Save and exit

#chmod +x PRCNAT.sh                                               // Provide executable permission.

Run Firewall:

# sh PRCNAT.sh

Now It will work for PRC NAT GW.