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cribs… first some SNAT script

What is SNAT:

Process of network address translation done in a secure way (also known as source network address translation or SNAT for short). This process involves re-writing the source and/or destination addresses of IP packets as they pass through a router or firewall.

very simple bash script to SNAT to common use (with no fireworks :))

#! /bin/bash
# Marcin Rybak
#
# External IP (from WAN side)
EXTIP=”xxx.xxx.xxx.xxx”

# External iface
EXTIF=”eth0″

# Local network to SNAT”
INT_NET=”192.168.0.0/24″

# Path to IPTABLES (check if in your system is the same)
IPTABLES=”/usr/sbin/iptables”

echo “[+] Enabling ip forwarding”
echo “1″ > /proc/sys/net/ipv4/ip_forward

echo “[+] Cleaning existing tables”
$IPTABLES -t nat -F POSTROUTING
$IPTABLES -t nat -F PREROUTING
$IPTABLES -F FORWARD
$IPTABLES -P FORWARD ACCEPT

echo “[+] Turning on SNAT”
$IPTABLES -A POSTROUTING -t nat -s $INT_NET -j SNAT –to $EXTIP
echo “[+] I think it’s DONE”

Tags: bash, iptables, script, snat