#!/bin/bash

# TOPO:
# host1 172.16.1.1/24 <-> .254/24 RTR  .254/24 <-> 192.168.1.1/24 host2
#                     <-> .253/24 RTR2 .254/24 <-> 192.168.2.1/24 host3

netns_list="host1 host2 host3 RTR RTR2"
for i in $netns_list; do
	ip netns del $i > /dev/null 2>&1
done
for i in $netns_list; do
	ip netns add $i
done
ip link add host1_eth1 type veth peer name RTR_eth1
ip link add host1_eth2 type veth peer name RTR2_eth1
ip link add host2_eth1 type veth peer name RTR_eth2
ip link add host3_eth1 type veth peer name RTR2_eth2
ip link set RTR_eth1 netns RTR
ip link set RTR2_eth1 netns RTR2
ip link set RTR_eth2 netns RTR
ip link set RTR2_eth2 netns RTR2
ip link set host1_eth1 netns host1
ip link set host1_eth2 netns host1
ip link set host2_eth1 netns host2
ip link set host3_eth1 netns host3

ip netns exec host1 brctl addbr host1_br0
ip netns exec host1 brctl addif host1_br0 host1_eth1
ip netns exec host1 brctl addif host1_br0 host1_eth2
ip netns exec host1 ifconfig host1_br0 172.16.1.1/24 up
ip netns exec host1 ip link set host1_eth1 up
ip netns exec host1 ip link set host1_eth2 up

ip netns exec RTR ifconfig RTR_eth1 172.16.1.254/24 up
ip netns exec RTR2 ifconfig RTR2_eth1 172.16.1.253/24 up
ip netns exec RTR ifconfig RTR_eth2 192.168.1.254/24 up
ip netns exec RTR2 ifconfig RTR2_eth2 192.168.2.254/24 up
ip netns exec RTR sysctl -w net.ipv4.conf.all.forwarding=1
ip netns exec RTR2 sysctl -w net.ipv4.conf.all.forwarding=1

ip netns exec RTR sysctl -w net.ipv4.conf.RTR_eth1.bc_forwarding=1
ip netns exec RTR2 sysctl -w net.ipv4.conf.RTR2_eth1.bc_forwarding=1
ip netns exec RTR sysctl -w net.ipv4.conf.all.bc_forwarding=1
ip netns exec RTR2 sysctl -w net.ipv4.conf.all.bc_forwarding=1

ip netns exec host2 ifconfig host2_eth1 192.168.1.1/24 up
ip netns exec host3 ifconfig host3_eth1 192.168.2.1/24 up

ip netns exec host1 ip route add default nexthop via 172.16.1.254 nexthop via 172.16.1.253
ip netns exec host2 ip route add default via 192.168.1.254
ip netns exec host3 ip route add default via 192.168.2.254

ip netns exec host2 sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=0
ip netns exec host3 sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=0
ip netns exec RTR sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=0
ip netns exec RTR2 sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=0

ip netns exec host1 ping 192.168.2.255 -c 1
# ip netns exec host3 tcpdump -i host3_eth1 -p icmp -nn

# ip netns exec host1 ping 192.168.1.255 -c 1
# ip netns exec host2 tcpdump -i host2_eth1 -p icmp -nn

# ip netns exec host1 ping 255.255.255.255 -c 1