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nixpkgs/nixos/tests/clatd.nix
Jared Baur d4d5fd718d
nixos/clatd: make client fetch PLAT prefix dynamically
We can expose the PLAT prefix to the client via DNS64 so clatd is able
to determine the prefix dynamically. We can also test that some
systemd-networkd PREF64 settings work as expected when exposed on the
router.
2024-06-11 00:41:10 -07:00

237 lines
7.3 KiB
Nix

# 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])
'';
})