anchor.diff:        virtualisation.vlans = [ 0 ];
         networking = {
           dhcpcd.enable = false;
  -        defaultGateway = ifAddr nodes.moon "eth1";
  +        defaultGateway = "192.168.0.3";
         };
       };
   
       moon = {pkgs, config, nodes, ...} :
  -      let
  -        carolIp = ifAddr nodes.carol "eth1";
  -        moonIp  = ifAddr nodes.moon  "eth2";
  -        strongswan = config.services.strongswan-swanctl.package;
  +      let strongswan = config.services.strongswan-swanctl.package;
         in {
           virtualisation.vlans = [ 0 1 ];
           networking = {
  
positive.code: import ./make-test.nix ({ pkgs, ...} :
  
  let
    ifAddr = node: iface: (pkgs.lib.head node.config.networking.interfaces.${iface}.ip4).address;
  
    allowESP = "iptables --insert INPUT --protocol ESP --jump ACCEPT";
  
    # Shared VPN settings:
    vlan0         = "192.168.0.0/24";
    version       = 2;
    secret        = "0sFpZAZqEN6Ti9sqt4ZP5EWcqx";
    esp_proposals = [ "aes128gcm128-x25519" ];
  
negative.code:       };
  
      carol = {pkgs, config, nodes, ...} :
        let strongswan = config.services.strongswan-swanctl.package;
        in {
          virtualisation.vlans = [ 1 ];
          networking = {
  