# This test verifies that we can ping an IPv4-only server from an IPv6-only
# client via a NAT64 router using CLAT on the client. The hosts and networks
# are configured as follows:
#
# +------
# Client | clat Address: 192.0.0.1/32 (configured via clatd)
# | Route: default
# |
# | eth1 Address: Assigned via SLAAC within 2001:db8::/64
# | | Route: default via IPv6LL address
# +--|---
# | VLAN 3
# +--|---
# | eth2 Address: 2001:db8::1/64
# Router |
# | nat64 Address: 64:ff9b::1/128
# | Route: 64:ff9b::/96
# | Address: 192.0.2.0/32
# | Route: 192.0.2.0/24
# |
# | eth1 Address: 100.64.0.1/24
# +--|---
# | VLAN 2
# +--|---
# Server | eth1 Address: 100.64.0.2/24
# | Route: 192.0.2.0/24 via 100.64.0.1
# +------
import ./make-test-python.nix ({ pkgs, lib, ... }:
{
name = "clatd";
meta = with pkgs.lib.maintainers; {
maintainers = [ hax404 jmbaur ];
};
nodes = {
# The server is configured with static IPv4 addresses. RFC 6052 Section 3.1
# disallows the mapping of non-global IPv4 addresses like RFC 1918 into the
# Well-Known Prefix 64:ff9b::/96. TAYGA also does not allow the mapping of
# documentation space (RFC 5737). To circumvent this, 100.64.0.2/24 from
# RFC 6589 (Carrier Grade NAT) is used here.
# To reach the IPv4 address pool of the NAT64 gateway, there is a static
# route configured. In normal cases, where the router would also source NAT
# the pool addresses to one IPv4 addresses, this would not be needed.
server = {
virtualisation.vlans = [
2 # towards router
];
networking = {
useDHCP = false;
interfaces.eth1 = lib.mkForce {};
};
systemd.network = {
enable = true;
networks."vlan1" = {
matchConfig.Name = "eth1";
address = [
"100.64.0.2/24"
];
routes = [
{ Destination = "192.0.2.0/24"; Gateway = "100.64.0.1"; }
];
};
};
};
# The router is configured with static IPv4 addresses towards the server
# and IPv6 addresses towards the client. DNS64 is exposed towards the
# client so clatd is able to auto-discover the PLAT prefix. For NAT64, the
# Well-Known prefix 64:ff9b::/96 is used. NAT64 is done with TAYGA which
# provides the tun-interface nat64 and does the translation over it. The
# IPv6 packets are sent to this interfaces and received as IPv4 packets and
# vice versa. As TAYGA only translates IPv6 addresses to dedicated IPv4
# addresses, it needs a pool of IPv4 addresses which must be at least as
# big as the expected amount of clients. In this test, the packets from the
# pool are directly routed towards the client. In normal cases, there would
# be a second source NAT44 to map all clients behind one IPv4 address.
router = {
boot.kernel.sysctl = {
"net.ipv4.conf.all.forwarding" = 1;
"net.ipv6.conf.all.forwarding" = 1;
};
virtualisation.vlans = [
2 # towards server
3 # towards client
];
networking = {
useDHCP = false;
useNetworkd = true;
firewall.enable = false;
interfaces.eth1 = lib.mkForce {
ipv4 = {
addresses = [ { address = "100.64.0.1"; prefixLength = 24; } ];
};
};
interfaces.eth2 = lib.mkForce {
ipv6 = {
addresses = [ { address = "2001:db8::1"; prefixLength = 64; } ];
};
};
};
systemd.network.networks."40-eth2" = {
networkConfig.IPv6SendRA = true;
ipv6Prefixes = [ { Prefix = "2001:db8::/64"; } ];
ipv6PREF64Prefixes = [ { Prefix = "64:ff9b::/96"; } ];
ipv6SendRAConfig = {
EmitDNS = true;
DNS = "_link_local";
};
};
services.resolved.extraConfig = ''
DNSStubListener=no
'';
networking.extraHosts = ''
192.0.0.171 ipv4only.arpa
192.0.0.170 ipv4only.arpa
'';
services.coredns = {
enable = true;
config = ''
.:53 {
bind ::
hosts /etc/hosts
dns64 64:ff9b::/96
}
'';
};
services.tayga = {
enable = true;
ipv4 = {
address = "192.0.2.0";
router = {
address = "192.0.2.1";
};
pool = {
address = "192.0.2.0";
prefixLength = 24;
};
};
ipv6 = {
address = "2001:db8::1";
router = {
address = "64:ff9b::1";
};
pool = {
address = "64:ff9b::";
prefixLength = 96;
};
};
};
};
# The client uses SLAAC to assign IPv6 addresses. To reach the IPv4-only
# server, the client starts the clat daemon which starts and configures the
# local IPv4 -> IPv6 translation via Tayga after discovering the PLAT
# prefix via DNS64.
client = {
virtualisation.vlans = [
3 # towards router
];
networking = {
useDHCP = false;
interfaces.eth1 = lib.mkForce {};
};
systemd.network = {
enable = true;
networks."vlan1" = {
matchConfig.Name = "eth1";
# NOTE: clatd does not actually use the PREF64 prefix discovered by
# systemd-networkd (nor does systemd-networkd do anything with it,
# yet), but we set this to confirm it works. See the test script
# below.
ipv6AcceptRAConfig.UsePREF64 = true;
};
};
services.clatd = {
enable = true;
# NOTE: Perl's Net::DNS resolver does not seem to work well querying
# for AAAA records to systemd-resolved's default IPv4 bind address
# (127.0.0.53), so we add an IPv6 listener address to systemd-resolved
# and tell clatd to use that instead.
settings.dns64-servers = "::1";
};
# Allow clatd to find dns server. See comment above.
services.resolved.extraConfig = ''
DNSStubListenerExtra=::1
'';
environment.systemPackages = [ pkgs.mtr ];
};
};
testScript = ''
import json
start_all()
# wait for all machines to start up
for machine in client, router, server:
machine.wait_for_unit("network-online.target")
with subtest("Wait for tayga and clatd"):
router.wait_for_unit("tayga.service")
client.wait_for_unit("clatd.service")
# clatd checks if this system has IPv4 connectivity for 10 seconds
client.wait_until_succeeds(
'journalctl -u clatd -e | grep -q "Starting up TAYGA, using config file"'
)
with subtest("networkd exports PREF64 prefix"):
assert json.loads(client.succeed("networkctl status eth1 --json=short"))[
"NDisc"
]["PREF64"][0]["Prefix"] == [0x0, 0x64, 0xFF, 0x9B] + ([0] * 12)
with subtest("Test ICMP"):
client.wait_until_succeeds("ping -c 3 100.64.0.2 >&2")
with subtest("Test ICMP and show a traceroute"):
client.wait_until_succeeds("mtr --show-ips --report-wide 100.64.0.2 >&2")
client.log(client.execute("systemd-analyze security clatd.service")[1])
'';
})