nixpkgs/nixos/tests/nat.nix

# This is a simple distributed test involving a topology with two
# separate virtual networks - the "inside" and the "outside" - with a
# client on the inside network, a server on the outside network, and a
# router connected to both that performs Network Address Translation
# for the client.
import ./make-test.nix ({ withFirewall, ... }:
  let
    unit = if withFirewall then "firewall" else "nat";
  in
  {
    name = "nat${if withFirewall then "WithFirewall" else "Standalone"}";

    nodes =
      { client =
          { config, pkgs, nodes, ... }:
          { virtualisation.vlans = [ 1 ];
            networking.firewall.allowPing = true;
            networking.defaultGateway =
              (pkgs.lib.head nodes.router.config.networking.interfaces.eth2.ip4).address;
          };

        router =
          { config, pkgs, ... }:
          { virtualisation.vlans = [ 2 1 ];
            networking.firewall.enable = withFirewall;
            networking.firewall.allowPing = true;
            networking.nat.enable = true;
            networking.nat.internalIPs = [ "192.168.1.0/24" ];
            networking.nat.externalInterface = "eth1";
          };

        server =
          { config, pkgs, ... }:
          { virtualisation.vlans = [ 2 ];
            networking.firewall.enable = false;
            services.httpd.enable = true;
            services.httpd.adminAddr = "foo@example.org";
            services.vsftpd.enable = true;
            services.vsftpd.anonymousUser = true;
          };
      };

    testScript =
      { nodes, ... }:
      ''
        startAll;

        # The router should have access to the server.
        $server->waitForUnit("network.target");
        $server->waitForUnit("httpd");
        $router->waitForUnit("network.target");
        $router->succeed("curl --fail http://server/ >&2");

        # The client should be also able to connect via the NAT router.
        $router->waitForUnit("${unit}");
        $client->waitForUnit("network.target");
        $client->succeed("curl --fail http://server/ >&2");
        $client->succeed("ping -c 1 server >&2");

        # Test whether passive FTP works.
        $server->waitForUnit("vsftpd");
        $server->succeed("echo Hello World > /home/ftp/foo.txt");
        $client->succeed("curl -v ftp://server/foo.txt >&2");

        # Test whether active FTP works.
        $client->succeed("curl -v -P - ftp://server/foo.txt >&2");

        # Test ICMP.
        $client->succeed("ping -c 1 router >&2");
        $router->succeed("ping -c 1 client >&2");

        # If we turn off NAT, the client shouldn't be able to reach the server.
        $router->succeed("iptables -t nat -D PREROUTING -j nixos-nat-pre");
        $router->succeed("iptables -t nat -D POSTROUTING -j nixos-nat-post");
        $client->fail("curl --fail --connect-timeout 5 http://server/ >&2");
        $client->fail("ping -c 1 server >&2");

        # And make sure that reloading the NAT job works.
        $router->succeed("systemctl restart ${unit}");
        $client->succeed("curl --fail http://server/ >&2");
        $client->succeed("ping -c 1 server >&2");
      '';
  })