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Chapter 3 Container Networking Intro

The following steps show how to create the networking setup.

  1. Create a host with a root network namespace.
  2. Create two new network namespace.
  3. Create two veth pair.
  4. Move one side of each veth pair into a new network namespace.
  5. Address side of the veth pair inside the new network namespace.
  6. Create a bridge interface.
  7. Attach bridge to the host interface.
  8. Attach one side of each veth pair to the bridge interface.
  9. Test
      br-veth0          veth0  +-------------+
         +--------------------- + net0       |
         |       192.168.1.100 +-------------+
+--------+
|        |
| br1    | 192.168.1.10
|        |
+--------+
         |              veth1  +-------------+
         +---------------------+ net1        |
      br-veth1   192.168.1.101 +-------------+

1. Create a host with a root network namespace.

Follow the steps from Chapter 1 to start a Vagrant Host.

Connect to the machine

vagrant ssh

2. Create a new network namespace.

vagrant@ubuntu-xenial:~$ sudo ip netns list
vagrant@ubuntu-xenial:~$ sudo ip netns add net0
vagrant@ubuntu-xenial:~$ sudo ip netns add net1
vagrant@ubuntu-xenial:~$ sudo ip netns list
net1
net0

3. Create veth pairs.

vagrant@ubuntu-xenial:~$ sudo ip link add veth0 type veth peer name br-veth0
vagrant@ubuntu-xenial:~$ sudo ip link add veth1 type veth peer name br-veth1
vagrant@ubuntu-xenial:~$ ip link list veth1
7: veth1@br-veth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 2a:92:85:81:50:50 brd ff:ff:ff:ff:ff:ff
vagrant@ubuntu-xenial:~$ ip link list veth0
5: veth0@br-veth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 0a:a1:be:3c:89:3d brd ff:ff:ff:ff:ff:ff

4. Move one side of the veth pair into a new network namespace.

Move veth0 int net0 namespace, and veth1 into net1

vagrant@ubuntu-xenial:~$ sudo ip link set veth0 netns net0
vagrant@ubuntu-xenial:~$ sudo ip link set veth1 netns net1

Examine the network namespaces

vagrant@ubuntu-xenial:~$ sudo ip netns exec net1 ip link list veth1
7: veth1@if6: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 2a:92:85:81:50:50 brd ff:ff:ff:ff:ff:ff link-netnsid 0

vagrant@ubuntu-xenial:~$ sudo ip netns exec net0 ip link list veth0
5: veth0@if4: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 0a:a1:be:3c:89:3d brd ff:ff:ff:ff:ff:ff link-netnsid 0

5. Address side of the veth pair inside the new network namespace.

Address veths

vagrant@ubuntu-xenial:~$ sudo ip netns exec net0 ip addr add "192.168.1.100/24" dev veth0
vagrant@ubuntu-xenial:~$ sudo ip netns exec net1 ip addr add "192.168.1.101/24" dev veth1

Turn up the veth side

sudo ip netns exec net0 ip link set dev veth0 up
sudo ip netns exec net1 ip link set dev veth1 up
vagrant@ubuntu-xenial:~$ sudo ip netns exec net0 ip link list
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN mode DEFAULT group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
5: veth0@if4: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state LOWERLAYERDOWN mode DEFAULT group default qlen 1000
    link/ether 0a:a1:be:3c:89:3d brd ff:ff:ff:ff:ff:ff link-netnsid 0
vagrant@ubuntu-xenial:~$ sudo ip netns exec net1 ip link list
1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN mode DEFAULT group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
7: veth1@if6: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state LOWERLAYERDOWN mode DEFAULT group default qlen 1000
    link/ether 2a:92:85:81:50:50 brd ff:ff:ff:ff:ff:ff link-netnsid 0

6. Create a bridge interface.

Create a bridge interface, turn it on, and address it.

sudo ip link add name br1 type bridge
sudo ip link set br1 up
sudo ip addr add 192.168.1.10/24 brd + dev br1

7. Attach bridge to the host interface.

sudo ip link set enp0s8 master br1

Turn each side of the veth pair that will attach to the bridge, up.

sudo ip link set br-veth0 up
sudo ip link set br-veth1 up

8. Attach one side of the veth pair to the bridge interface.

sudo ip link set br-veth0 master br1
sudo ip link set br-veth1 master br1

9. Test.

From the host ping .10, .100 and .101

vagrant@ubuntu-xenial:~$ ping 192.168.1.10
PING 192.168.1.10 (192.168.1.10) 56(84) bytes of data.
64 bytes from 192.168.1.10: icmp_seq=1 ttl=64 time=0.011 ms
64 bytes from 192.168.1.10: icmp_seq=2 ttl=64 time=0.038 ms
64 bytes from 192.168.1.10: icmp_seq=3 ttl=64 time=0.038 ms
64 bytes from 192.168.1.10: icmp_seq=4 ttl=64 time=0.021 ms
vagrant@ubuntu-xenial:~$ ping 192.168.1.100
PING 192.168.1.100 (192.168.1.100) 56(84) bytes of data.
64 bytes from 192.168.1.100: icmp_seq=1 ttl=64 time=0.017 ms
64 bytes from 192.168.1.100: icmp_seq=2 ttl=64 time=0.027 ms
64 bytes from 192.168.1.100: icmp_seq=3 ttl=64 time=0.048 ms
vagrant@ubuntu-xenial:~$ ping 192.168.1.101
PING 192.168.1.101 (192.168.1.101) 56(84) bytes of data.
64 bytes from 192.168.1.101: icmp_seq=1 ttl=64 time=0.049 ms
64 bytes from 192.168.1.101: icmp_seq=2 ttl=64 time=0.028 ms
64 bytes from 192.168.1.101: icmp_seq=3 ttl=64 time=0.038 ms

Now from the perspective namespaces ping each other.

vagrant@ubuntu-xenial:~$ sudo ip netns exec net0 ping -c 4 192.168.1.101
PING 192.168.1.101 (192.168.1.101) 56(84) bytes of data.
64 bytes from 192.168.1.101: icmp_seq=1 ttl=64 time=0.085 ms
64 bytes from 192.168.1.101: icmp_seq=2 ttl=64 time=0.054 ms
64 bytes from 192.168.1.101: icmp_seq=3 ttl=64 time=0.029 ms
64 bytes from 192.168.1.101: icmp_seq=4 ttl=64 time=0.030 ms

--- 192.168.1.101 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3000ms
rtt min/avg/max/mdev = 0.029/0.049/0.085/0.023 ms
vagrant@ubuntu-xenial:~$ sudo ip netns exec net1 ping -c 4 192.168.1.100
PING 192.168.1.100 (192.168.1.100) 56(84) bytes of data.
64 bytes from 192.168.1.100: icmp_seq=1 ttl=64 time=0.020 ms
64 bytes from 192.168.1.100: icmp_seq=2 ttl=64 time=0.045 ms
64 bytes from 192.168.1.100: icmp_seq=3 ttl=64 time=0.029 ms
64 bytes from 192.168.1.100: icmp_seq=4 ttl=64 time=0.034 ms

--- 192.168.1.100 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 2998ms
rtt min/avg/max/mdev = 0.020/0.032/0.045/0.009 ms