os-nat_tables.sh

#!/bin/bash
###########################################
#  program: nat_tables.sh                 #
#  Author: Diarmuid O'Briain              #
#  Copyright ©2017 C2S Consulting         #
#  License: www.gnu.org/licenses/gpl.txt  #
###########################################
# NAT masquerade rules for hypervisor, hosting OpenStack testbed #
# Select interface, typically 'wlp4s0' for WIFI and 'enp0s3' for wired Ethernet
INTERFACE=eth0     # Unhash for wired Ethernet interface
#INTERFACE=enp3s0     # Unhash for wired Ethernet interface
#INTERFACE=wlp4s0    # Unhash for wireless WIFI interface
# Select instance private network
#NETWORK=virbr2
NETWORK=vboxnet1
# Flush iptables
sudo iptables -F
sudo iptables -F -t nat
# Enable IP forwarding
# For KVM/QEMU
# For VirtualBox
echo
echo "echo \"1\" > /proc/sys/net/ipv4/ip_forward"
sudo echo "1" > /proc/sys/net/ipv4/ip_forward
echo
# Load GNU/Linux kernel modules
sudo modprobe ip_tables
sudo modprobe ip_conntrack
# Add IPTABLES rules
sudo iptables -t nat -A POSTROUTING -o $INTERFACE -j MASQUERADE
sudo iptables -A FORWARD -i $INTERFACE -o $NETWORK -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A FORWARD -i $NETWORK -o $INTERFACE -j ACCEPT
# Print iptables
sudo iptables -t nat -v -L POSTROUTING
echo
sudo iptables -v -L FORWARD
# END