292 lines
12 KiB
Nix
292 lines
12 KiB
Nix
# This test verifies that we can request and assign IPv6 prefixes from upstream
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# (e.g. ISP) routers.
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# The setup consits of three VMs. One for the ISP, as your residential router
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# and the third as a client machine in the residential network.
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#
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# There are two VLANs in this test:
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# - VLAN 1 is the connection between the ISP and the router
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# - VLAN 2 is the connection between the router and the client
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import ./make-test-python.nix ({pkgs, ...}: {
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name = "systemd-networkd-ipv6-prefix-delegation";
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meta = with pkgs.lib.maintainers; {
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maintainers = [ andir ];
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};
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nodes = {
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# The ISP's routers job is to delegate IPv6 prefixes via DHCPv6. Like with
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# regular IPv6 auto-configuration it will also emit IPv6 router
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# advertisements (RAs). Those RA's will not carry a prefix but in contrast
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# just set the "Other" flag to indicate to the receiving nodes that they
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# should attempt DHCPv6.
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#
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# Note: On the ISPs device we don't really care if we are using networkd in
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# this example. That being said we can't use it (yet) as networkd doesn't
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# implement the serving side of DHCPv6. We will use ISC's well aged dhcpd6
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# for that task.
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isp = { lib, pkgs, ... }: {
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virtualisation.vlans = [ 1 ];
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networking = {
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useDHCP = false;
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firewall.enable = false;
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interfaces.eth1.ipv4.addresses = lib.mkForce []; # no need for legacy IP
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interfaces.eth1.ipv6.addresses = lib.mkForce [
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{ address = "2001:DB8::1"; prefixLength = 64; }
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];
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};
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# Since we want to program the routes that we delegate to the "customer"
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# into our routing table we must have a way to gain the required privs.
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# This security wrapper will do in our test setup.
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#
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# DO NOT COPY THIS TO PRODUCTION AS IS. Think about it at least twice.
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# Everyone on the "isp" machine will be able to add routes to the kernel.
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security.wrappers.add-dhcpd-lease = {
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source = pkgs.writeShellScript "add-dhcpd-lease" ''
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exec ${pkgs.iproute2}/bin/ip -6 route replace "$1" via "$2"
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'';
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capabilities = "cap_net_admin+ep";
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};
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services = {
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# Configure the DHCPv6 server
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#
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# We will hand out /48 prefixes from the subnet 2001:DB8:F000::/36.
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# That gives us ~8k prefixes. That should be enough for this test.
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#
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# Since (usually) you will not receive a prefix with the router
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# advertisements we also hand out /128 leases from the range
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# 2001:DB8:0000:0000:FFFF::/112.
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dhcpd6 = {
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enable = true;
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interfaces = [ "eth1" ];
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extraConfig = ''
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subnet6 2001:DB8::/36 {
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range6 2001:DB8:0000:0000:FFFF:: 2001:DB8:0000:0000:FFFF::FFFF;
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prefix6 2001:DB8:F000:: 2001:DB8:FFFF:: /48;
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}
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# This is the secret sauce. We have to extract the prefix and the
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# next hop when commiting the lease to the database. dhcpd6
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# (rightfully) has not concept of adding routes to the systems
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# routing table. It really depends on the setup.
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#
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# In a production environment your DHCPv6 server is likely not the
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# router. You might want to consider BGP, custom NetConf calls, …
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# in those cases.
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on commit {
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set IP = pick-first-value(binary-to-ascii(16, 16, ":", substring(option dhcp6.ia-na, 16, 16)), "n/a");
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set Prefix = pick-first-value(binary-to-ascii(16, 16, ":", suffix(option dhcp6.ia-pd, 16)), "n/a");
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set PrefixLength = pick-first-value(binary-to-ascii(10, 8, ":", substring(suffix(option dhcp6.ia-pd, 17), 0, 1)), "n/a");
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log(concat(IP, " ", Prefix, " ", PrefixLength));
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execute("/run/wrappers/bin/add-dhcpd-lease", concat(Prefix,"/",PrefixLength), IP);
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}
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'';
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};
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# Finally we have to set up the router advertisements. While we could be
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# using networkd or bird for this task `radvd` is probably the most
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# venerable of them all. It was made explicitly for this purpose and
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# the configuration is much more straightforward than what networkd
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# requires.
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# As outlined above we will have to set the `Managed` flag as otherwise
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# the clients will not know if they should do DHCPv6. (Some do
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# anyway/always)
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radvd = {
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enable = true;
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config = ''
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interface eth1 {
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AdvSendAdvert on;
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AdvManagedFlag on;
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AdvOtherConfigFlag off; # we don't really have DNS or NTP or anything like that to distribute
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prefix ::/64 {
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AdvOnLink on;
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AdvAutonomous on;
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};
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};
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'';
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};
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};
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};
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# This will be our (residential) router that receives the IPv6 prefix (IA_PD)
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# and /128 (IA_NA) allocation.
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#
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# Here we will actually start using networkd.
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router = {
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virtualisation.vlans = [ 1 2 ];
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systemd.services.systemd-networkd.environment.SYSTEMD_LOG_LEVEL = "debug";
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boot.kernel.sysctl = {
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# we want to forward packets from the ISP to the client and back.
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"net.ipv6.conf.all.forwarding" = 1;
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};
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networking = {
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useNetworkd = true;
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useDHCP = false;
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# Consider enabling this in production and generating firewall rules
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# for fowarding/input from the configured interfaces so you do not have
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# to manage multiple places
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firewall.enable = false;
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};
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systemd.network = {
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networks = {
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# systemd-networkd will load the first network unit file
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# that matches, ordered lexiographically by filename.
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# /etc/systemd/network/{40-eth1,99-main}.network already
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# exists. This network unit must be loaded for the test,
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# however, hence why this network is named such.
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# Configuration of the interface to the ISP.
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# We must request accept RAs and request the PD prefix.
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"01-eth1" = {
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name = "eth1";
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networkConfig = {
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Description = "ISP interface";
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IPv6AcceptRA = true;
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#DHCP = false; # no need for legacy IP
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};
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linkConfig = {
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# We care about this interface when talking about being "online".
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# If this interface is in the `routable` state we can reach
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# others and they should be able to reach us.
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RequiredForOnline = "routable";
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};
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# This configures the DHCPv6 client part towards the ISPs DHCPv6 server.
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dhcpV6Config = {
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# We have to include a request for a prefix in our DHCPv6 client
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# request packets.
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# Otherwise the upstream DHCPv6 server wouldn't know if we want a
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# prefix or not. Note: On some installation it makes sense to
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# always force that option on the DHPCv6 server since there are
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# certain CPEs that are just not setting this field but happily
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# accept the delegated prefix.
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PrefixDelegationHint = "::/48";
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};
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ipv6SendRAConfig = {
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# Let networkd know that we would very much like to use DHCPv6
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# to obtain the "managed" information. Not sure why they can't
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# just take that from the upstream RAs.
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Managed = true;
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};
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};
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# Interface to the client. Here we should redistribute a /64 from
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# the prefix we received from the ISP.
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"01-eth2" = {
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name = "eth2";
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networkConfig = {
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Description = "Client interface";
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# The client shouldn't be allowed to send us RAs, that would be weird.
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IPv6AcceptRA = false;
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# Delegate prefixes from the DHCPv6 PD pool.
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DHCPv6PrefixDelegation = true;
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IPv6SendRA = true;
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};
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# In a production environment you should consider setting these as well:
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# ipv6SendRAConfig = {
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#EmitDNS = true;
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#EmitDomains = true;
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#DNS= = "fe80::1"; # or whatever "well known" IP your router will have on the inside.
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# };
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# This adds a "random" ULA prefix to the interface that is being
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# advertised to the clients.
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# Not used in this test.
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# ipv6Prefixes = [
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# {
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# ipv6PrefixConfig = {
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# AddressAutoconfiguration = true;
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# PreferredLifetimeSec = 1800;
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# ValidLifetimeSec = 1800;
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# };
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# }
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# ];
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};
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# finally we are going to add a static IPv6 unique local address to
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# the "lo" interface. This will serve as ICMPv6 echo target to
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# verify connectivity from the client to the router.
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"01-lo" = {
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name = "lo";
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addresses = [
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{ addressConfig.Address = "FD42::1/128"; }
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];
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};
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};
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};
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# make the network-online target a requirement, we wait for it in our test script
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systemd.targets.network-online.wantedBy = [ "multi-user.target" ];
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};
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# This is the client behind the router. We should be receving router
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# advertisements for both the ULA and the delegated prefix.
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# All we have to do is boot with the default (networkd) configuration.
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client = {
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virtualisation.vlans = [ 2 ];
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systemd.services.systemd-networkd.environment.SYSTEMD_LOG_LEVEL = "debug";
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networking = {
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useNetworkd = true;
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useDHCP = false;
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};
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# make the network-online target a requirement, we wait for it in our test script
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systemd.targets.network-online.wantedBy = [ "multi-user.target" ];
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};
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};
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testScript = ''
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# First start the router and wait for it it reach a state where we are
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# certain networkd is up and it is able to send out RAs
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router.start()
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router.wait_for_unit("systemd-networkd.service")
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# After that we can boot the client and wait for the network online target.
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# Since we only care about IPv6 that should not involve waiting for legacy
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# IP leases.
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client.start()
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client.wait_for_unit("network-online.target")
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# the static address on the router should not be reachable
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client.wait_until_succeeds("ping -6 -c 1 FD42::1")
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# the global IP of the ISP router should still not be a reachable
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router.fail("ping -6 -c 1 2001:DB8::1")
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# Once we have internal connectivity boot up the ISP
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isp.start()
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# Since for the ISP "being online" should have no real meaning we just
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# wait for the target where all the units have been started.
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# It probably still takes a few more seconds for all the RA timers to be
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# fired etc..
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isp.wait_for_unit("multi-user.target")
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# wait until the uplink interface has a good status
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router.wait_for_unit("network-online.target")
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router.wait_until_succeeds("ping -6 -c1 2001:DB8::1")
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# shortly after that the client should have received it's global IPv6
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# address and thus be able to ping the ISP
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client.wait_until_succeeds("ping -6 -c1 2001:DB8::1")
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# verify that we got a globally scoped address in eth1 from the
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# documentation prefix
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ip_output = client.succeed("ip --json -6 address show dev eth1")
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import json
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ip_json = json.loads(ip_output)[0]
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assert any(
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addr["local"].upper().startswith("2001:DB8:")
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for addr in ip_json["addr_info"]
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if addr["scope"] == "global"
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)
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'';
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})
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