docs/usecases/container_test.md


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194

@media only all and (prefers-color-scheme: dark) {
.highlight .hll { background-color: #49483e }
.highlight .c { color: #75715e } /* Comment */
.highlight .err { color: #960050; background-color: #1e0010 } /* Error */
.highlight .k { color: #66d9ef } /* Keyword */
.highlight .l { color: #ae81ff } /* Literal */
.highlight .n { color: #f8f8f2 } /* Name */
.highlight .o { color: #f92672 } /* Operator */
.highlight .p { color: #f8f8f2 } /* Punctuation */
.highlight .ch { color: #75715e } /* Comment.Hashbang */
.highlight .cm { color: #75715e } /* Comment.Multiline */
.highlight .cp { color: #75715e } /* Comment.Preproc */
.highlight .cpf { color: #75715e } /* Comment.PreprocFile */
.highlight .c1 { color: #75715e } /* Comment.Single */
.highlight .cs { color: #75715e } /* Comment.Special */
.highlight .gd { color: #f92672 } /* Generic.Deleted */
.highlight .ge { font-style: italic } /* Generic.Emph */
.highlight .gi { color: #a6e22e } /* Generic.Inserted */
.highlight .gs { font-weight: bold } /* Generic.Strong */
.highlight .gu { color: #75715e } /* Generic.Subheading */
.highlight .kc { color: #66d9ef } /* Keyword.Constant */
.highlight .kd { color: #66d9ef } /* Keyword.Declaration */
.highlight .kn { color: #f92672 } /* Keyword.Namespace */
.highlight .kp { color: #66d9ef } /* Keyword.Pseudo */
.highlight .kr { color: #66d9ef } /* Keyword.Reserved */
.highlight .kt { color: #66d9ef } /* Keyword.Type */
.highlight .ld { color: #e6db74 } /* Literal.Date */
.highlight .m { color: #ae81ff } /* Literal.Number */
.highlight .s { color: #e6db74 } /* Literal.String */
.highlight .na { color: #a6e22e } /* Name.Attribute */
.highlight .nb { color: #f8f8f2 } /* Name.Builtin */
.highlight .nc { color: #a6e22e } /* Name.Class */
.highlight .no { color: #66d9ef } /* Name.Constant */
.highlight .nd { color: #a6e22e } /* Name.Decorator */
.highlight .ni { color: #f8f8f2 } /* Name.Entity */
.highlight .ne { color: #a6e22e } /* Name.Exception */
.highlight .nf { color: #a6e22e } /* Name.Function */
.highlight .nl { color: #f8f8f2 } /* Name.Label */
.highlight .nn { color: #f8f8f2 } /* Name.Namespace */
.highlight .nx { color: #a6e22e } /* Name.Other */
.highlight .py { color: #f8f8f2 } /* Name.Property */
.highlight .nt { color: #f92672 } /* Name.Tag */
.highlight .nv { color: #f8f8f2 } /* Name.Variable */
.highlight .ow { color: #f92672 } /* Operator.Word */
.highlight .w { color: #f8f8f2 } /* Text.Whitespace */
.highlight .mb { color: #ae81ff } /* Literal.Number.Bin */
.highlight .mf { color: #ae81ff } /* Literal.Number.Float */
.highlight .mh { color: #ae81ff } /* Literal.Number.Hex */
.highlight .mi { color: #ae81ff } /* Literal.Number.Integer */
.highlight .mo { color: #ae81ff } /* Literal.Number.Oct */
.highlight .sa { color: #e6db74 } /* Literal.String.Affix */
.highlight .sb { color: #e6db74 } /* Literal.String.Backtick */
.highlight .sc { color: #e6db74 } /* Literal.String.Char */
.highlight .dl { color: #e6db74 } /* Literal.String.Delimiter */
.highlight .sd { color: #e6db74 } /* Literal.String.Doc */
.highlight .s2 { color: #e6db74 } /* Literal.String.Double */
.highlight .se { color: #ae81ff } /* Literal.String.Escape */
.highlight .sh { color: #e6db74 } /* Literal.String.Heredoc */
.highlight .si { color: #e6db74 } /* Literal.String.Interpol */
.highlight .sx { color: #e6db74 } /* Literal.String.Other */
.highlight .sr { color: #e6db74 } /* Literal.String.Regex */
.highlight .s1 { color: #e6db74 } /* Literal.String.Single */
.highlight .ss { color: #e6db74 } /* Literal.String.Symbol */
.highlight .bp { color: #f8f8f2 } /* Name.Builtin.Pseudo */
.highlight .fm { color: #a6e22e } /* Name.Function.Magic */
.highlight .vc { color: #f8f8f2 } /* Name.Variable.Class */
.highlight .vg { color: #f8f8f2 } /* Name.Variable.Global */
.highlight .vi { color: #f8f8f2 } /* Name.Variable.Instance */
.highlight .vm { color: #f8f8f2 } /* Name.Variable.Magic */
.highlight .il { color: #ae81ff } /* Literal.Number.Integer.Long */
}
@media (prefers-color-scheme: light) {
.highlight .hll { background-color: #ffffcc }
.highlight .c { color: #888888 } /* Comment */
.highlight .err { color: #a61717; background-color: #e3d2d2 } /* Error */
.highlight .k { color: #008800; font-weight: bold } /* Keyword */
.highlight .ch { color: #888888 } /* Comment.Hashbang */
.highlight .cm { color: #888888 } /* Comment.Multiline */
.highlight .cp { color: #cc0000; font-weight: bold } /* Comment.Preproc */
.highlight .cpf { color: #888888 } /* Comment.PreprocFile */
.highlight .c1 { color: #888888 } /* Comment.Single */
.highlight .cs { color: #cc0000; font-weight: bold; background-color: #fff0f0 } /* Comment.Special */
.highlight .gd { color: #000000; background-color: #ffdddd } /* Generic.Deleted */
.highlight .ge { font-style: italic } /* Generic.Emph */
.highlight .gr { color: #aa0000 } /* Generic.Error */
.highlight .gh { color: #333333 } /* Generic.Heading */
.highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */
.highlight .go { color: #888888 } /* Generic.Output */
.highlight .gp { color: #555555 } /* Generic.Prompt */
.highlight .gs { font-weight: bold } /* Generic.Strong */
.highlight .gu { color: #666666 } /* Generic.Subheading */
.highlight .gt { color: #aa0000 } /* Generic.Traceback */
.highlight .kc { color: #008800; font-weight: bold } /* Keyword.Constant */
.highlight .kd { color: #008800; font-weight: bold } /* Keyword.Declaration */
.highlight .kn { color: #008800; font-weight: bold } /* Keyword.Namespace */
.highlight .kp { color: #008800 } /* Keyword.Pseudo */
.highlight .kr { color: #008800; font-weight: bold } /* Keyword.Reserved */
.highlight .kt { color: #888888; font-weight: bold } /* Keyword.Type */
.highlight .m { color: #0000DD; font-weight: bold } /* Literal.Number */
.highlight .s { color: #dd2200; background-color: #fff0f0 } /* Literal.String */
.highlight .na { color: #336699 } /* Name.Attribute */
.highlight .nb { color: #003388 } /* Name.Builtin */
.highlight .nc { color: #bb0066; font-weight: bold } /* Name.Class */
.highlight .no { color: #003366; font-weight: bold } /* Name.Constant */
.highlight .nd { color: #555555 } /* Name.Decorator */
.highlight .ne { color: #bb0066; font-weight: bold } /* Name.Exception */
.highlight .nf { color: #0066bb; font-weight: bold } /* Name.Function */
.highlight .nl { color: #336699; font-style: italic } /* Name.Label */
.highlight .nn { color: #bb0066; font-weight: bold } /* Name.Namespace */
.highlight .py { color: #336699; font-weight: bold } /* Name.Property */
.highlight .nt { color: #bb0066; font-weight: bold } /* Name.Tag */
.highlight .nv { color: #336699 } /* Name.Variable */
.highlight .ow { color: #008800 } /* Operator.Word */
.highlight .w { color: #bbbbbb } /* Text.Whitespace */
.highlight .mb { color: #0000DD; font-weight: bold } /* Literal.Number.Bin */
.highlight .mf { color: #0000DD; font-weight: bold } /* Literal.Number.Float */
.highlight .mh { color: #0000DD; font-weight: bold } /* Literal.Number.Hex */
.highlight .mi { color: #0000DD; font-weight: bold } /* Literal.Number.Integer */
.highlight .mo { color: #0000DD; font-weight: bold } /* Literal.Number.Oct */
.highlight .sa { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Affix */
.highlight .sb { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Backtick */
.highlight .sc { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Char */
.highlight .dl { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Delimiter */
.highlight .sd { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Doc */
.highlight .s2 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Double */
.highlight .se { color: #0044dd; background-color: #fff0f0 } /* Literal.String.Escape */
.highlight .sh { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Heredoc */
.highlight .si { color: #3333bb; background-color: #fff0f0 } /* Literal.String.Interpol */
.highlight .sx { color: #22bb22; background-color: #f0fff0 } /* Literal.String.Other */
.highlight .sr { color: #008800; background-color: #fff0ff } /* Literal.String.Regex */
.highlight .s1 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Single */
.highlight .ss { color: #aa6600; background-color: #fff0f0 } /* Literal.String.Symbol */
.highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */
.highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */
.highlight .vc { color: #336699 } /* Name.Variable.Class */
.highlight .vg { color: #dd7700 } /* Name.Variable.Global */
.highlight .vi { color: #3333bb } /* Name.Variable.Instance */
.highlight .vm { color: #336699 } /* Name.Variable.Magic */
.highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */
}
21.01-rc0~353-g40aa27ef7
Container-based network simulation
==================================

The "make test" framework provides a good way to test individual
features. However, when testing several features at once - or
validating nontrivial configurations - it may prove difficult or
impossible to use the unit-test framework.

This note explains how to set up lxc/lxd, and a 5-container testbed to
test a split-tunnel nat + ikev2 + ipsec + ipv6 prefix-delegation
scenario.

OS / Distro test results
------------------------

This setup has been tested on an Ubuntu 18.04 LTS system. If you're
feeling adventurous, the same scenario also worked on a recent Ubuntu
20.04 "preview" daily build.

Other distros may work fine, or not at all.

Proxy Server
------------

If you need to use a proxy server e.g. from a lab system, you'll
probably need to set HTTP_PROXY, HTTPS_PROXY, http_proxy and
https_proxy in /etc/environment. Directly setting variables in the
environment doesn't work. The lxd snap _daemon_ needs the proxy settings,
not the user interface.

Something like so:

```
    HTTP_PROXY=http://my.proxy.server:8080
    HTTPS_PROXY=http://my.proxy.server:4333
    http_proxy=http://my.proxy.server:8080
    https_proxy=http://my.proxy.server:4333
```

Install and configure lxd
-------------------------

Install the lxd snap. The lxd snap is up to date, as opposed to the
results of "sudo apt-get install lxd".

```
    # snap install lxd
    # lxd init
```

"lxd init" asks several questions. With the exception of the storage
pool, take the defaults. To match the configs shown below, create a
storage pool named "vpp." Storage pools of type "zfs" and "files" have
been tested successfully.

zfs is more space-efficient. "lxc copy" is infinitely faster with
zfs. The path for the zfs storage pool is under /var. Do not replace
it with a symbolic link, unless you want to rebuild all of your
containers from scratch. Ask me how I know that.

Create three network segments
-----------------------------

Aka, linux bridges.

```
    # lxc network create respond
    # lxc network create internet
    # lxc network create initiate
```

We'll explain the test topology in a bit. Stay tuned.

Set up the default container profile
------------------------------------

Execute "lxc profile edit default", and install the following
configuration. Note that the "shared" directory should mount your vpp
workspaces. With that trick, you can edit code from any of the
containers, run vpp without installing it, etc.

```
    config: {}
    description: Default LXD profile
    devices:
      eth0:
        name: eth0
        network: lxdbr0
        type: nic
      eth1:
        name: eth1
        nictype: bridged
        parent: internet
        type: nic
      eth2:
        name: eth2
        nictype: bridged
        parent: respond
        type: nic
      eth3:
        name: eth3
        nictype: bridged
        parent: initiate
        type: nic
      root:
        path: /
        pool: vpp
        type: disk
      shared:
        path: /scratch
        source: /scratch
        type: disk
    name: default
```

Set up the network configurations
---------------------------------

Edit the fake "internet" backbone:

```
  # lxc network edit internet
```

Install the ip addresses shown below, to avoid having to rebuild the vpp
and host configuration:

```
    config:
      ipv4.address: 10.26.68.1/24
      ipv4.dhcp.ranges: 10.26.68.10-10.26.68.50
      ipv4.nat: "true"
      ipv6.address: none
      ipv6.nat: "false"
    description: ""
    name: internet
    type: bridge
    used_by:
    managed: true
    status: Created
    locations:
    - none
```

Repeat the process with the "respond" and "initiate" networks, using these
configurations:

### respond network configuration

```
    config:
      ipv4.address: 10.166.14.1/24
      ipv4.dhcp.ranges: 10.166.14.10-10.166.14.50
      ipv4.nat: "true"
      ipv6.address: none
      ipv6.nat: "false"
    description: ""
    name: respond
    type: bridge
    used_by:
    managed: true
    status: Created
    locations:
    - none
```
### initiate network configuration

```
    config:
      ipv4.address: 10.219.188.1/24
      ipv4.dhcp.ranges: 10.219.188.10-10.219.188.50
      ipv4.nat: "true"
      ipv6.address: none
      ipv6.nat: "false"
    description: ""
    name: initiate
    type: bridge
    used_by:
    managed: true
    status: Created
    locations:
    - none
```

Create a "master" container image
---------------------------------

The master container image should be set up so that you can
build vpp, ssh into the container, edit source code, run gdb, etc.

Make sure that e.g. public key auth ssh works.

```
    # lxd launch ubuntu:18.04 respond
    <spew>
    # lxc exec respond bash
    respond# cd /scratch/my-vpp-workspace
    respond# apt-get install make ssh
    respond# make install-dep
    respond# exit
    # lxc stop respond
```

Mark the container image privileged. If you forget this step, you'll
trip over a netlink error (-11) aka EAGAIN when you try to roll in the
vpp configurations.

```
    # lxc config set respond security.privileged "true"
```

Duplicate the "master" container image
--------------------------------------

To avoid having to configure N containers, be sure that the master
container image is fully set up before you help it have children:

```
    # lxc copy respond respondhost
    # lxc copy respond initiate
    # lxc copy respond initiatehost
    # lxc copy respond dhcpserver    # optional, to test ipv6 prefix delegation
```

Install handy script
--------------------

See below for a handly script which executes lxc commands across the
current set of running containers. I call it "lxc-foreach," feel free
to call the script Ishmael if you like.

Examples:

```
    $ lxc-foreach start
    <issues "lxc start" for each container in the list>
```

After a few seconds, use this one to open an ssh connection to each
container. The ssh command parses the output of "lxc info," which
displays container ip addresses.

```
    $ lxc-foreach ssh
```

Here's the script:

```
    #!/bin/bash

    set -u
    export containers="respond respondhost initiate initiatehost dhcpserver"

    if [ x$1 = "x" ] ; then
        echo missing command
        exit 1
    fi

    if [ $1 = "ssh" ] ; then
        for c in $containers
        do
            inet=`lxc info $c | grep eth0 | grep -v inet6 | head -1 | cut -f 3`
            if [ x$inet = "x" ] ; then
                echo $c not started
            else
                gnome-terminal --command "/usr/bin/ssh $inet"
            fi
        done
    exit 0
    fi

    for c in $containers
    do
        echo lxc $1 $c
        lxc $1 $c
    done

    exit 0
```

Test topology
-------------

Finally, we're ready to describe a test topology. First, a picture:

```
    ===+======== management lan/bridge lxdbr0 (dhcp) ===========+===
       |                             |                          |
       |                             |                          |
       |                             |                          |
       v                             |                          v
      eth0                           |                         eth0
    +------+ eth1                                       eth1 +------+
    | respond | 10.26.88.100 <= internet bridge => 10.26.88.101 | initiate |
    +------+                                                 +------+
      eth2 / bvi0 10.166.14.2        |       10.219.188.2 eth3 / bvi0
       |                             |                          |
       | ("respond" bridge)             |          ("initiate" bridge) |
       |                             |                          |
       v                             |                          v
      eth2 10.166.14.3               |           eth3 10.219.188.3
    +----------+                     |                   +----------+
    | respondhost |                     |                   | respondhost |
    +----------+                     |                   +----------+
      eth0 (management lan) <========+========> eth0 (management lan)
```

### Test topology discussion

This topology is suitable for testing almost any tunnel encap/decap
scenario.  The two containers "respondhost" and "initiatehost" are end-stations
connected to two vpp instances running on "respond" and "initiate".

We leverage the Linux end-station network stacks to generate traffic
of all sorts.

The so-called "internet" bridge models the public internet. The "respond" and
"initiate" bridges connect vpp instances to local hosts

End station configs
-------------------

The end-station Linux configurations set up the eth2 and eth3 ip
addresses shown above, and add tunnel routes to the opposite
end-station networks.

### respondhost configuration

```
    ifconfig eth2 10.166.14.3/24 up
    route add -net 10.219.188.0/24 gw 10.166.14.2
```

### initiatehost configuration

```
    sudo ifconfig eth3 10.219.188.3/24 up
    sudo route add -net 10.166.14.0/24 gw 10.219.188.2
```

VPP configs
-----------

Split nat44 / ikev2 + ipsec tunneling, with ipv6 prefix delegation in
the "respond" config.

### respond configuration

```
    set term pag off

    comment { "internet" }
    create host-interface name eth1
    set int ip address host-eth1 10.26.68.100/24
    set int ip6 table host-eth1 0
    set int state host-eth1 up

    comment { default route via initiate }
    ip route add 0.0.0.0/0 via 10.26.68.101

    comment { "respond-private-net" }
    create host-interface name eth2
    bvi create instance 0
    set int l2 bridge bvi0 1 bvi
    set int ip address bvi0 10.166.14.2/24
    set int state bvi0 up
    set int l2 bridge host-eth2 1
    set int state host-eth2 up


    nat44 add interface address host-eth1
    set interface nat44 in host-eth2 out host-eth1
    nat44 add identity mapping external host-eth1 udp 500
    nat44 add identity mapping external host-eth1 udp 4500
    comment { nat44 untranslated subnet 10.219.188.0/24 }

    comment { responder profile }
    ikev2 profile add initiate
    ikev2 profile set initiate udp-encap
    ikev2 profile set initiate auth rsa-sig cert-file /scratch/setups/respondcert.pem
    set ikev2 local key /scratch/setups/initiatekey.pem
    ikev2 profile set initiate id local fqdn initiator.my.net
    ikev2 profile set initiate id remote fqdn responder.my.net
    ikev2 profile set initiate traffic-selector remote ip-range 10.219.188.0 - 10.219.188.255 port-range 0 - 65535 protocol 0
    ikev2 profile set initiate traffic-selector local ip-range 10.166.14.0 - 10.166.14.255 port-range 0 - 65535 protocol 0
    create ipip tunnel src 10.26.68.100 dst 10.26.68.101
    ikev2 profile set initiate tunnel ipip0

    comment { ipv6 prefix delegation }
    ip6 nd address autoconfig host-eth1 default-route
    dhcp6 client host-eth1
    dhcp6 pd client host-eth1 prefix group hgw
    set ip6 address bvi0 prefix group hgw ::2/56
    ip6 nd address autoconfig bvi0 default-route
    ip6 nd bvi0 ra-interval 5 3 ra-lifetime 180

    set int mtu packet 1390 ipip0
    set int unnum ipip0 use host-eth1
    ip route add 10.219.188.0/24 via ipip0
```

### initiate configuration

```
    set term pag off

    comment { "internet" }
    create host-interface name eth1
    comment { set dhcp client intfc host-eth1 hostname initiate }
    set int ip address host-eth1 10.26.68.101/24
    set int state host-eth1 up

    comment { default route via "internet gateway" }
    comment { ip route add 0.0.0.0/0 via 10.26.68.1 }

    comment { "initiate-private-net" }
    create host-interface name eth3
    bvi create instance 0
    set int l2 bridge bvi0 1 bvi
    set int ip address bvi0 10.219.188.2/24
    set int state bvi0 up
    set int l2 bridge host-eth3 1
    set int state host-eth3 up

    nat44 add interface address host-eth1
    set interface nat44 in bvi0 out host-eth1
    nat44 add identity mapping external host-eth1 udp 500
    nat44 add identity mapping external host-eth1 udp 4500
    comment { nat44 untranslated subnet 10.166.14.0/24 }

    comment { initiator profile }
    ikev2 profile add respond
    ikev2 profile set respond udp-encap
    ikev2 profile set respond auth rsa-sig cert-file /scratch/setups/initiatecert.pem
    set ikev2 local key /scratch/setups/respondkey.pem
    ikev2 profile set respond id local fqdn responder.my.net
    ikev2 profile set respond id remote fqdn initiator.my.net

    ikev2 profile set respond traffic-selector remote ip-range 10.166.14.0 - 10.166.14.255 port-range 0 - 65535 protocol 0
    ikev2 profile set respond traffic-selector local ip-range 10.219.188.0 - 10.219.188.255 port-range 0 - 65535 protocol 0

    ikev2 profile set respond responder host-eth1 10.26.68.100
    ikev2 profile set respond ike-crypto-alg aes-cbc 256  ike-integ-alg sha1-96  ike-dh modp-2048
    ikev2 profile set respond esp-crypto-alg aes-cbc 256  esp-integ-alg sha1-96  esp-dh ecp-256
    ikev2 profile set respond sa-lifetime 3600 10 5 0

    create ipip tunnel src 10.26.68.101 dst 10.26.68.100
    ikev2 profile set respond tunnel ipip0
    ikev2 initiate sa-init respond

    set int mtu packet 1390 ipip0
    set int unnum ipip0 use host-eth1
    ip route add 10.166.14.0/24 via ipip0
```

IKEv2 certificate setup
-----------------------

In both of the vpp configurations, you'll see "/scratch/setups/xxx.pem"
mentioned. These certificates are used in the ikev2 key exchange.

Here's how to generate the certificates:

```
    openssl req -x509 -nodes -newkey rsa:4096 -keyout respondkey.pem -out respondcert.pem -days 3560
    openssl x509 -text -noout -in respondcert.pem
    openssl req -x509 -nodes -newkey rsa:4096 -keyout initiatekey.pem -out initiatecert.pem -days 3560
    openssl x509 -text -noout -in initiatecert.pem
```

Make sure that the "respond" and "initiate" configurations point to the certificates.

DHCPv6 server setup
-------------------

If you need an ipv6 dhcp server to test ipv6 prefix delegation,
create the "dhcpserver" container as shown above.

Install the "isc-dhcp-server" Debian package:

```
    sudo apt-get install isc-dhcp-server
```

### /etc/dhcp/dhcpd6.conf

Edit the dhcpv6 configuration and add an ipv6 subnet with prefix
delegation. For example:

```
    subnet6 2001:db01:0:1::/64 {
            range6 2001:db01:0:1::1 2001:db01:0:1::9;
            prefix6 2001:db01:0:100:: 2001:db01:0:200::/56;
    }
```

Add an ipv6 address on eth1, which is connected to the "internet"
bridge, and start the dhcp server. I use the following trivial bash
script, which runs the dhcp6 server in the foreground and produces
dhcp traffic spew:

```
    #!/bin/bash
    ifconfig eth1 inet6 add 2001:db01:0:1::10/64 || true
    dhcpd -6 -d -cf /etc/dhcp/dhcpd6.conf
```

The "|| true" bit keeps going if eth1 already has the indicated ipv6
address.

Container / Host Interoperation
-------------------------------

Host / container interoperation is highly desirable. If the host and a
set of containers don't run the same distro _and distro version_, it's
reasonably likely that the glibc versions won't match. That, in turn,
makes vpp binaries built in one environment fail in the other.

Trying to install multiple versions of glibc - especially at the host
level - often ends very badly and is _not recommended_. It's not just
glibc, either. The dynamic loader ld-linux-xxx-so.2 is glibc version
specific.

Fortunately, it's reasonable easy to build lxd container images based on
specific Ubuntu or Debian versions.

### Create a custom root filesystem image

First, install the "debootstrap" tool:

```
    sudo apt-get install debootstrap
```

Make a temp directory, and use debootstrap to populate it. In this
example, we create an Ubuntu 20.04 (focal fossa) base image:

```
    # mkdir /tmp/myroot
    # debootstrap focal /tmp/myroot http://archive.ubuntu.com/ubuntu
```

To tinker with the base image (if desired):

```
    # chroot /tmp/myroot
    <add packages, etc.>
    # exit
```

Make a compressed tarball of the base image:

```
    # tar zcf /tmp/rootfs.tar.gz -C /tmp/myroot .
```

Create a "metadata.yaml" file which describes the base image:

```
    architecture: "x86_64"
    # To get current date in Unix time, use `date +%s` command
    creation_date: 1458040200
    properties:
    architecture: "x86_64"
    description: "My custom Focal Fossa image"
    os: "Ubuntu"
    release: "focal"
```

Make a compressed tarball of metadata.yaml:

```
    # tar zcf metadata.tar.gz metadata.yaml
```

Import the image into lxc / lxd:

```
    $ lxc image import metadata.tar.gz rootfd.tar.gz --alias focal-base
```

### Create a container which uses the customized base image:

```
    $ lxc launch focal-base focaltest
    $ lxc exec focaltest bash
```

The next several steps should be executed in the container, in the
bash shell spun up by "lxc exec..."

### Configure container networking

In the container, create /etc/netplan/50-cloud-init.yaml:

```
    network:
        version: 2
        ethernets:
            eth0:
                dhcp4: true
```

Use "cat > /etc/netplan/50-cloud-init.yaml", and cut-'n-paste if your
favorite text editor is AWOL.

Apply the configuration:

```
    # netplan apply
```

At this point, eth0 should have an ip address, and you should see
a default route with "route -n".

### Configure apt

Again, in the container, set up /etc/apt/sources.list via cut-'n-paste
from a recently update "focal fossa" host. Something like so:

```
    deb http://us.archive.ubuntu.com/ubuntu/ focal main restricted
    deb http://us.archive.ubuntu.com/ubuntu/ focal-updates main restricted
    deb http://us.archive.ubuntu.com/ubuntu/ focal universe
    deb http://us.archive.ubuntu.com/ubuntu/ focal-updates universe
    deb http://us.archive.ubuntu.com/ubuntu/ focal multiverse
    deb http://us.archive.ubuntu.com/ubuntu/ focal-updates multiverse
    deb http://us.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
    deb http://security.ubuntu.com/ubuntu focal-security main restricted
    deb http://security.ubuntu.com/ubuntu focal-security universe
    deb http://security.ubuntu.com/ubuntu focal-security multiverse
```

"apt-get update" and "apt-install" should produce reasonable results.
Suggest "apt-get install make git".

At this point, you can use the "/scratch" sharepoint (or similar) to
execute "make install-dep install-ext-deps" to set up the container
with the vpp toolchain; proceed as desired.