linux_bridge.sh

#!/bin/bash

set -o pipefail

string="$1"

if [ "$string" = "up" ]; then
ip netns add net1
ip netns add net2

ip link add veth1 type veth peer name vethpeer1
ip link add veth2 type veth peer name vethpeer2

ip link set veth1 up
ip link set veth2 up

ip link set vethpeer1 netns net1
ip link set vethpeer2 netns net2

ip netns exec net1 ip link set lo up
ip netns exec net2 ip link set lo up
ip netns exec net1 ip link set vethpeer1 up
ip netns exec net2 ip link set vethpeer2 up

ip netns exec net1 ip addr add 10.100.0.10/16 dev vethpeer1
ip netns exec net2 ip addr add 10.100.0.20/16 dev vethpeer2

ip link add br00 type bridge
ip link set br00 up

ip link set veth1 master br00
ip link set veth2 master br00

ip addr add 10.100.0.1/16 dev br00

ip netns exec net1 ip route add default via 10.100.0.1
ip netns exec net2 ip route add default via 10.100.0.1

ip netns exec net1 ping -c 3 10.100.0.20

ip netns exec net2 ping -c 3 10.100.0.10


echo ""
echo ""
echo "Enabling ip_forwarding ...."
echo ""

sleep 2

bash -c 'echo 1 > /proc/sys/net/ipv4/ip_forward'
iptables -t nat -A POSTROUTING -s 10.100.0.1/16 ! -o br00 -j MASQUERADE

echo ""
echo "Ping Google DNS....."
echo ""
sleep 2

ip netns exec net1 ping -c 3 8.8.8.8

fi



if [ "$1" == "down" ]; then

ip netns delete net1
ip netns delete net2

ip link delete br00

bash -c 'echo 0 > /proc/sys/net/ipv4/ip_forward'

fi