add hacky wwan service with hardcoding all over

examples/l2tp.nix

@@ -31,10 +31,8 @@ in rec {
   ];
   hostname = "thing";
 
-  services.dhcpc =
-    let iface = config.hardware.networkInterfaces.lan;
-    in svc.network.dhcp.client.build {
-      interface = iface;
+  services.dhcpc = svc.network.dhcp.client.build {
+    interface = config.services.wwan;
     dependencies = [ config.services.hostname ];
   };
 
@@ -85,6 +83,4 @@ in rec {
     passwd = lib.mkForce secrets.root.passwd;
     openssh.authorizedKeys.keys = secrets.root.keys;
   };
-
-
 }

modules/cdc-ncm/default.nix

@@ -1,5 +1,8 @@
-{ config, ... }:
-{
+{ config, pkgs, lib, ... }:
+let
+  inherit (pkgs.liminix.services) oneshot;
+  svc = config.system.service;
+in {
   config = {
     kernel.config = {
       USB_NET_HUAWEI_CDC_NCM = "y";
@@ -8,6 +11,33 @@
       USB_SERIAL_OPTION = "y";
     };
 
+    # https://www.0xf8.org/2017/01/flashing-a-huawei-e3372h-4g-lte-stick-from-hilink-to-stick-mode/
+
+    services.wwan = let
+      chat = lib.escapeShellArgs [
+        "" "AT"
+        "OK" "ATZ"
+        "OK" "AT+CGDCONT=1,\"IP\",\"data.uk\""
+        "OK"  "AT+CGACT=1,1"
+        # caret is special to chat, so needs escaping in AT commands
+        "OK"  "AT\\^AUTHDATA=1,2,\"1p\",\"one2one\",\"user\""
+        "OK" "AT\\^NDISDUP=1,1" # ,\"data.uk\",\"user\",\"one2one\",2"
+      ];
+      modemConfig = oneshot {
+        name = "modem-configure";
+        up = ''
+          sleep 2
+          ${pkgs.usb-modeswitch}/bin/usb_modeswitch -v 12d1 -p 14fe --huawei-new-mode
+          sleep 5
+          ${pkgs.ppp}/bin/chat -s -v ${chat}  0<>/dev/ttyUSB0 1>&0
+        '';
+        down = "chat -v '' ATZ OK  </dev/ttyUSB0 >&0";
+      };
+    in svc.network.link.build {
+      ifname = "wwan0";
+      dependencies = [ modemConfig ];
+    };
+
     # an ncm ethernet adaptor does
     # * usb modeswitch
     # * AT commands
@@ -19,4 +49,3 @@
     # https://stackoverflow.com/questions/5477882/how-to-i-detect-whether-a-tty-belonging-to-a-gsm-3g-modem-is-a-data-or-control-p
   };
 }
-