diff --git a/src/infuse_iot/database.py b/src/infuse_iot/database.py
index e32e0d6..53f46ca 100644
--- a/src/infuse_iot/database.py
+++ b/src/infuse_iot/database.py
@@ -132,6 +132,9 @@ def _bt_adv_key(self, base: bytes, time_idx: int) -> bytes:
     def _bt_gatt_key(self, base: bytes, time_idx: int) -> bytes:
         return hkdf_derive(base, time_idx.to_bytes(4, "little"), b"bt_gatt")
 
+    def _udp_key(self, base: bytes, time_idx: int) -> bytes:
+        return hkdf_derive(base, time_idx.to_bytes(4, "little"), b"udp")
+
     def has_public_key(self, address: int) -> bool:
         """Does the database have the public key for this device?"""
         if address not in self.devices:
@@ -219,3 +222,27 @@ def bt_gatt_device_key(self, address: int, gps_time: int) -> bytes:
         time_idx = gps_time // (60 * 60 * 24)
 
         return self._bt_gatt_key(base, time_idx)
+
+    def udp_network_key(self, address: int, gps_time: int) -> bytes:
+        """Network key for UDP interface"""
+        if address not in self.devices:
+            raise DeviceUnknownNetworkKey
+        network_id = self.devices[address].network_id
+        if network_id is None:
+            raise DeviceUnknownNetworkKey
+
+        return self._network_key(network_id, b"udp", gps_time)
+
+    def udp_device_key(self, address: int, gps_time: int) -> bytes:
+        """Device key for UDP interface"""
+        if address not in self.devices:
+            raise DeviceUnknownDeviceKey
+        d = self.devices[address]
+        if d.device_id is None:
+            raise DeviceUnknownDeviceKey
+        base = self.devices[address].shared_key
+        if base is None:
+            raise DeviceUnknownDeviceKey
+        time_idx = gps_time // (60 * 60 * 24)
+
+        return self._udp_key(base, time_idx)
diff --git a/src/infuse_iot/epacket/packet.py b/src/infuse_iot/epacket/packet.py
index 660ccb7..b8cdb07 100644
--- a/src/infuse_iot/epacket/packet.py
+++ b/src/infuse_iot/epacket/packet.py
@@ -337,18 +337,8 @@ class CtypeForwardHeaderBtGatt(ctypes.LittleEndianStructure):
     _pack_ = 1
 
 
-class CtypeV0VersionedFrame(ctypes.LittleEndianStructure):
-    _fields_ = [
-        ("version", ctypes.c_uint8),
-        ("_type", ctypes.c_uint8),
-        ("flags", ctypes.c_uint16),
-        ("_key_metadata", ctypes.c_uint8 * 3),
-        ("_device_id_upper", ctypes.c_uint32),
-        ("_device_id_lower", ctypes.c_uint32),
-        ("gps_time", ctypes.c_uint32),
-        ("sequence", ctypes.c_uint16),
-        ("entropy", ctypes.c_uint16),
-    ]
+class CtypeV0Frame(ctypes.LittleEndianStructure):
+    _fields_ = []
     _pack_ = 1
 
     @property
@@ -381,6 +371,35 @@ def parse(cls, frame: bytes) -> tuple[Self, int]:
         )
 
 
+class CtypeV0VersionedFrame(CtypeV0Frame):
+    _fields_ = [
+        ("version", ctypes.c_uint8),
+        ("_type", ctypes.c_uint8),
+        ("flags", ctypes.c_uint16),
+        ("_key_metadata", ctypes.c_uint8 * 3),
+        ("_device_id_upper", ctypes.c_uint32),
+        ("_device_id_lower", ctypes.c_uint32),
+        ("gps_time", ctypes.c_uint32),
+        ("sequence", ctypes.c_uint16),
+        ("entropy", ctypes.c_uint16),
+    ]
+    _pack_ = 1
+
+
+class CtypeV0UnversionedFrame(CtypeV0Frame):
+    _fields_ = [
+        ("_type", ctypes.c_uint8),
+        ("flags", ctypes.c_uint16),
+        ("_key_metadata", ctypes.c_uint8 * 3),
+        ("_device_id_upper", ctypes.c_uint32),
+        ("_device_id_lower", ctypes.c_uint32),
+        ("gps_time", ctypes.c_uint32),
+        ("sequence", ctypes.c_uint16),
+        ("entropy", ctypes.c_uint16),
+    ]
+    _pack_ = 1
+
+
 class CtypeSerialFrame(CtypeV0VersionedFrame):
     """Serial packet header"""
 
@@ -484,6 +503,21 @@ def decrypt(cls, database: DeviceDatabase, bt_addr: Address.BluetoothLeAddr | No
         return header, decrypted
 
 
+class CtypeUdpFrame(CtypeV0UnversionedFrame):
+    @classmethod
+    def decrypt(cls, database: DeviceDatabase, frame: bytes):
+        header = cls.from_buffer_copy(frame)
+        if header.flags & Flags.ENCR_DEVICE:
+            database.observe_device(header.device_id, device_id=header.key_metadata)
+            key = database.udp_device_key(header.device_id, header.gps_time)
+        else:
+            database.observe_device(header.device_id, network_id=header.key_metadata)
+            key = database.udp_network_key(header.device_id, header.gps_time)
+
+        decrypted = chachapoly_decrypt(key, frame[:10], frame[10:22], frame[22:])
+        return header, decrypted
+
+
 class CtypePacketReceived:
     class CommonHeader(ctypes.Structure):
         _fields_ = [
diff --git a/src/infuse_iot/serial_comms.py b/src/infuse_iot/serial_comms.py
index 568a818..fe9b1fe 100644
--- a/src/infuse_iot/serial_comms.py
+++ b/src/infuse_iot/serial_comms.py
@@ -2,6 +2,7 @@
 
 import time
 from abc import ABCMeta, abstractmethod
+from io import BufferedWriter
 
 import pylink
 import serial
@@ -43,7 +44,7 @@ def reconstructor(cls):
 
 class SerialLike(metaclass=ABCMeta):
     @abstractmethod
-    def open(self) -> None:
+    def open(self, timeout: float | None = None) -> None:
         """Open serial port"""
 
     @abstractmethod
@@ -79,7 +80,7 @@ def __init__(self, serial_port, baudrate=115200):
         # receivers (STM32) time to wake up on RX before real data arrives.
         self._prefix = b"\x00\x00" if baudrate > 115200 else b""
 
-    def open(self):
+    def open(self, timeout: float | None = None):
         self._ser.open()
 
     def read_bytes(self, num) -> bytes:
@@ -108,20 +109,25 @@ def __str__(self) -> str:
 class RttPort(SerialLike):
     """Segger RTT handling"""
 
-    def __init__(self, rtt_device):
+    def __init__(self, rtt_device: str, serial_number: str | None = None):
         self._jlink = pylink.JLink()
         self._name = rtt_device
-        self._modem_trace = None
+        self._serial_number = serial_number
+        self._modem_trace: BufferedWriter | None = None
         self._modem_trace_buf = 0
 
-    def open(self):
-        self._jlink.open()
+    def open(self, timeout: float | None = None):
+        self._jlink.open(serial_no=self._serial_number)
         self._jlink.set_tif(pylink.enums.JLinkInterfaces.SWD)
         self._jlink.connect(self._name, 4000)
         self._jlink.rtt_start()
 
+        end_time = time.time() + timeout if timeout else None
+
         # Loop until JLink initialised properly
         while True:
+            if end_time and time.time() > end_time:
+                raise TimeoutError("RTT port never initialised")
             try:
                 num_up = self._jlink.rtt_get_num_up_buffers()
                 _num_down = self._jlink.rtt_get_num_down_buffers()
@@ -179,7 +185,7 @@ def __init__(self, target: str):
         self._target = self._session.target
         self._rtt = GenericRTTControlBlock(self._target)
 
-    def open(self):
+    def open(self, timeout: float | None = None):
         self._session.open()
         self._target.resume()
         self._rtt.start()
diff --git a/src/infuse_iot/tools/provision.py b/src/infuse_iot/tools/provision.py
index c3d2506..79ab9e8 100644
--- a/src/infuse_iot/tools/provision.py
+++ b/src/infuse_iot/tools/provision.py
@@ -23,13 +23,6 @@
 from infuse_iot.util.soc import nrf, soc, stm
 
 
-class ProvisioningStruct(ctypes.LittleEndianStructure):
-    _fields_ = [
-        ("device_id", ctypes.c_uint64),
-    ]
-    _pack_ = 1
-
-
 class SubCommand(InfuseCommand):
     NAME = "provision"
     HELP = "Provision device on Infuse Cloud"
@@ -171,8 +164,8 @@ def run(self):
         assert isinstance(response.parsed.device_id, str)
         # Compare current flash contents to desired flash contents
         cloud_id = int(response.parsed.device_id, 16)
-        current_bytes = interface.read_provisioned_data(ctypes.sizeof(ProvisioningStruct))
-        desired = ProvisioningStruct(cloud_id)
+        current_bytes = interface.read_provisioned_data(ctypes.sizeof(interface.DefaultProvisioningStruct))
+        desired = interface.DefaultProvisioningStruct(cloud_id)
         desired_bytes = bytes(desired)
 
         if current_bytes == desired_bytes:
diff --git a/src/infuse_iot/util/soc/nrf.py b/src/infuse_iot/util/soc/nrf.py
index 4ffea4e..5b841ad 100644
--- a/src/infuse_iot/util/soc/nrf.py
+++ b/src/infuse_iot/util/soc/nrf.py
@@ -98,18 +98,22 @@ def __init__(self, snr: int | None):
         self.snr = snr
         devices = self._exec(["device-info"])
         if len(devices) == 0:
-            sys.exit()
+            raise RuntimeError("No devices found")
         devices_info = devices[0]["devices"]
 
-        if len(devices_info) > 1:
-            serials = ",".join([d["serialNumber"] for d in devices_info])
-            sys.exit(f"Multiple devices found without a SNR provided (Found: {serials})")
-        self.snr = devices_info[0]["serialNumber"]
-        self.device_info = devices_info[0]["deviceInfo"]
+        if snr is None:
+            if len(devices_info) > 1:
+                serials = ",".join([d["serialNumber"] for d in devices_info])
+                raise RuntimeError(f"Multiple devices found without a SNR provided (Found: {serials})")
+            self.snr = int(devices_info[0]["serialNumber"])
+        infos = [info for info in devices_info if int(info["serialNumber"]) == self.snr]
+        if len(infos) == 0:
+            raise RuntimeError(f"Devices with SNR {self.snr} not found")
+        self.device_info = infos[0]["deviceInfo"]
         self.core_info = self._exec(["core-info"])
         self.family = DEVICE_FAMILY_MAPPING[self.device_info["jlink"]["deviceFamily"]]
-        self.uicr_base = self.core_info[0]["devices"][0]["uicrAddress"]
-        self._soc_name = self.family.soc(self.device_info)
+        self.uicr_base: int = self.core_info[0]["devices"][0]["uicrAddress"]
+        self._soc_name: str = self.family.soc(self.device_info)
 
     def _exec(self, args: list[str]):
         jout_all = []
diff --git a/src/infuse_iot/util/soc/soc.py b/src/infuse_iot/util/soc/soc.py
index 2ddd7f8..923e1f1 100644
--- a/src/infuse_iot/util/soc/soc.py
+++ b/src/infuse_iot/util/soc/soc.py
@@ -1,11 +1,18 @@
 #!/usr/bin/env
 
+import ctypes
 from abc import ABCMeta, abstractmethod
 
 
 class ProvisioningInterface(metaclass=ABCMeta):
     "Generic SoC provisioning interface"
 
+    class DefaultProvisioningStruct(ctypes.LittleEndianStructure):
+        _fields_ = [
+            ("device_id", ctypes.c_uint64),
+        ]
+        _pack_ = 1
+
     @property
     @abstractmethod
     def soc_name(self) -> str: