liminix/examples/router-with-l2tp.nix

# A demonstration config for a home/soho router with PPPoE upstream
# and fallback to an L2TP tunnel over a USB WWAN device

{
  config,
  pkgs,
  lib,
  ...
}: let
  secrets = import ./extneder-secrets.nix;
  rsecrets = import ./rotuer-secrets.nix;

  # https://support.aa.net.uk/Category:Incoming_L2TP says:
  # "Please use the DNS name (l2tp.aa.net.uk) instead of hardcoding an
  # IP address; IP addresses can and do change. If you have to use an
  # IP, use 194.4.172.12, but do check the DNS for l2tp.aa.net.uk in
  # case it changes."

  # but (1) we don't want to use the wwan stick's dns as our main
  # resolver: it's provided by some mobile ISP and they aren't
  # necessarily the best at providing unfettered services without
  # deciding to do something weird; (2) it's not simple to arrange
  # that xl2tpd gets a different resolver than every other process;
  # (3) there's no way to specify an lns address to xl2tpd at runtime
  # except by rewriting its config file. So what we will do is lookup
  # the lns hostname using the mobile ISP's dns server and then refuse
  # to start l2tp unless the expected lns address is one of the
  # addresses returned. I think this satisfies "do check the DNS"

  lns = { hostname = "l2tp.aaisp.net.uk"; address = "194.4.172.12"; };

  inherit (pkgs.liminix.services) oneshot longrun target;
  inherit (pkgs.liminix) outputRef;
  inherit (pkgs.pseudofile) dir symlink;
  inherit (pkgs) serviceFns;
  svc = config.system.service;
  wirelessConfig = {
    country_code = "GB";
    inherit (rsecrets) wpa_passphrase;
    wmm_enabled = 1;
  };
in rec {
  boot = {
    tftp = {
      serverip = "10.0.0.1";
      ipaddr = "10.0.0.8";
    };
  };

  imports = [
    ../modules/wwan
    ../modules/network
    ../modules/ssh
    ../modules/usb.nix
    ../modules/ppp
    ../modules/round-robin
    ../modules/health-check
    ../modules/secrets
    ../modules/profiles/gateway.nix
  ];
  hostname = "thing";

  services.wan-address-for-secrets = svc.network.address.build {
    interface = config.hardware.networkInterfaces.wan;
    family = "inet"; address ="10.0.0.10"; prefixLength = 24;
  };

  services.secrets = svc.secrets.outboard.build {
    name = "secret-service";
    url = "http://10.0.0.1/liminix/examples/real-secrets.json";
    username = "demo";
    password = "demo";
    interval = 5;
    dependencies = [ services.wan-address-for-secrets ];
  };

  services.wwan = svc.wwan.huawei-e3372.build {
    apn = "data.uk";
    username = "user";
    password = "one2one";
    authType = "chap";
  };

  profile.gateway = {
    lan = {
      interfaces =  with config.hardware.networkInterfaces;
        [
          # EDIT: these are the interfaces exposed by the gl.inet gl-ar750:
          # if your device has more or differently named lan interfaces,
          # specify them here
          wlan wlan5
          lan
        ];
      inherit (rsecrets.lan) prefix;
      address = {
        family = "inet"; address ="${rsecrets.lan.prefix}.1"; prefixLength = 24;
      };
      dhcp = {
        start = 10;
        end = 240;
        hosts = { } // lib.optionalAttrs (builtins.pathExists ./static-leases.nix) (import ./static-leases.nix);
        localDomain = "lan";
      };
    };
    wan =
      let
        secret = outputRef config.services.secrets;
        username = secret "ppp/username";
        password = secret "ppp/password";
      in {
        interface =
          let
            pppoe = svc.pppoe.build {
              interface = config.hardware.networkInterfaces.wan;
              debug = true;
              inherit username password;
            };

            l2tp =
              let
                check-address = oneshot rec {
                  name = "check-lns-address";
                  up = "grep -Fx ${lns.address} $(output_path ${services.lns-address} addresses)";
                  dependencies = [ services.lns-address ];
                };
                route = svc.network.route.build {
                  via = "$(output ${services.bootstrap-dhcpc} router)";
                  target = lns.address;
                  dependencies = [services.bootstrap-dhcpc check-address];
                };
                l2tpd= svc.l2tp.build {
                  lns = lns.address;
                  inherit username password;
                  dependencies = [config.services.lns-address route check-address];
                };
              in
                svc.health-check.build {
                  service = l2tpd;
                  threshold = 3;
                  interval = 2;
                  healthCheck = pkgs.writeAshScript "ping-check" {} "ping 1.1.1.1";
                };
          in svc.round-robin.build {
            name = "wan";
            services = [
              pppoe
              l2tp
            ];
          };
        dhcp6.enable = true;
      };

    wireless.networks = {
      "${rsecrets.ssid}" = {
        interface = config.hardware.networkInterfaces.wlan;
        hw_mode = "g";
        channel = "6";
        ieee80211n = 1;
      } // wirelessConfig // {
        wpa_passphrase = outputRef config.services.secrets "wpa_passphrase";
      };

      "${rsecrets.ssid}5" = rec {
        interface = config.hardware.networkInterfaces.wlan5;
        hw_mode = "a";
        channel = 36;
        ht_capab = "[HT40+]";
        vht_oper_chwidth = 1;
        vht_oper_centr_freq_seg0_idx = channel + 6;
        ieee80211n = 1;
        ieee80211ac = 1;
      } // wirelessConfig // {
        wpa_passphrase = outputRef config.services.secrets "wpa_passphrase";
      };
    };
  };

  services.bootstrap-dhcpc = svc.network.dhcp.client.build {
    interface = config.services.wwan;
    dependencies = [ config.services.hostname ];
  };

  services.sshd = svc.ssh.build {
    authorizedKeys = outputRef config.services.secrets "ssh/authorizedKeys";
  };

  services.lns-address = let
    ns = "$(output_word ${services.bootstrap-dhcpc} dns 1)";
    route-to-bootstrap-nameserver = svc.network.route.build {
      via = "$(output ${services.bootstrap-dhcpc} router)";
      target = ns;
      dependencies = [services.bootstrap-dhcpc];
    };
  in oneshot rec {
    name = "resolve-l2tp-server";
    dependencies = [ services.bootstrap-dhcpc route-to-bootstrap-nameserver ];
    up = ''
      (in_outputs ${name}
       DNSCACHEIP="${ns}" ${pkgs.s6-dns}/bin/s6-dnsip4 ${lns.hostname} \
        > addresses
      )
    '';
  };

  users.root = rsecrets.root;

  programs.busybox.options = {
    FEATURE_FANCY_TAIL = "y";
  };

}