This repository contains firmware and Wireshark extcap script that can be used with nRF52840 chip as an 802.15.4 sniffer.

Note: this project is experimental.

The software provided has been tested with the nRF52840-DK board and the following operating systems:

• Ubuntu 18.04 (Wireshark 2.4.5 from the official package, Wireshark 2.6.4)
• Windows 10 (Wireshark 2.6.3)
• macOS Mojave (Wireshark 2.6.4)

• Wireshark (Ubuntu package wireshark)
• pySerial (Ubuntu package python-serial or python3-serial)

To start using the sniffer, you must flash the firmware, install the script, and configure the sniffer in Wireshark.

1. Connect the nRF52840-DK to the PC with an USB cable by connecting it to the J2 USB port.
2. Flash the firmware with the following command:

nrfjprog -f nrf52 --program nrf802154_sniffer/nrf802154_sniffer.hex --chiperase -r

3. J2 USB port can now be optionally disconnected.
4. Connect the nRF52840-DK to J3 nRF USB port.

Note: Sniffer firmware can no longer transport captured packets over J2 USB port. Capture can be carried out using only the J3 nRF USB port.

1. Download and install nRF Connect for Desktop.
2. Click Add/remove apps and install Programmer application.
3. Plug the dongle to USB port and click reset button to enter DFU mode. Red diode should start blinking.
4. Select Nordic Semiconductor DFU Bootloader device from the list.
5. Click Add HEX file and select nrf802154_sniffer_dongle.hex from nrf802154_sniffer directory.
6. Verify that the selected application begins at the 0x00001000 address to avoid overwriting the MBR section.
7. Click Write to flash the device.
8. Unplug the dongle from the USB port and plug it again. Do not click the reset button.

To find the correct installation path of the extcap utility on any system please see:

"Help" -> "About Wireshark" -> "Folders" -> "Extcap path"

Copy the provided nrf802154_sniffer.py script to the extcap directory.

Note to Windows users: nrf802154_sniffer.bat has to be copied to the same directory as well. Ensure that Python directory is included in your PATH system environment variable.

1. During the Wireshark installation on Ubuntu the user will be prompted to choose one of the following options:

   • Create the wireshark user group and allow all members of that group to capture packets.
   • Only allow the root user to capture packets.

   Note: Using the Wireshark as the root user is strongly discouraged.

   To change the settings after the installation, run the following command:

   sudo dpkg-reconfigure wireshark-common

   If the Wireshark was configured to restrict the capture to members of the wireshark group, add the correct user to the group:

   sudo usermod -a -G wireshark [user]

2. Add the correct user to the dialout group:

   sudo usermod -a -G dialout [user]

3. Log-out and log-in again to apply the new user group settings.

4. Install the Python interpreter. The recommended version is 3.7.

5. Install the pySerial module. To install it, run one of the following commands:

   • Using Ubuntu's native package manager:

     sudo apt install python-serial

     Or alternatively:

     sudo apt install python3-serial

   • Using Python's pip package manager:

     sudo pip install pyserial

1. Install the python interpreter. The recommended version is 3.7. Make sure to check the Add Python to environment variables option during installation.
2. Install the pySerial module using the Python's pip package manager:

   sudo pip install pyserial

1. Run Wireshark.
2. Click the gear icon next to the 'nRF Sniffer for 802.15.4'.
3. Select the 802.15.4 channel.
4. Select the format for out-of-band meta-data.
5. Click 'Start'.

To decode packets exchanged on the Thread network, you must configure the Wireshark to use the correct decryption keys.

1. Go to Edit -> Preferences... -> Protocols -> IEEE 802.15.4 -> Decryption Keys.
2. Configure the following values:
   • Decryption key: 00112233445566778899aabbccddeeff (default value used by the Nordic Thread and Zigbee SDK examples)
   • Decryption key index:0
   • Key hash: Thread hash

Thread uses the CoAP protocol on port 61631 for network data exchange. To correctly decode packets sent over that port, you can use one of the following options:

• Apply the setting globally by editing CoAP protocol settings in Preferences and changing the CoAP UDP port value to 61631.
• Apply the setting on per-capture basis by adding an entry to Analyze -> Decode as... with the following values:
  • Field: UDP port
  • Value:61631
  • Current: CoAP

Go to 6loWPAN settings in Preferences window and add correct values. Contexts may vary depending on the Thread Network Data. Below values are used by Thread examples in nRF5 SDK.

• Context 0: fdde:ad00:beef:0::/64
• Context 1: fd11:22::/64

If Wireshark uses incorrect dissectors to decode a message you have an option to disable unwanted protocols. Go to Analyze -> Enabled protocols and uncheck unwanted protocols. Suggestions below.

• LwMesh
• ZigBee
• ZigBee Green Power

To capture the data for Zigbee examples in SDK, you must manually configure Wireshark:

1. Press Ctrl + Shift + P to enter the Wireshark preferences.
2. Go to Protocols -> Zigbee.
3. Click the Edit button next to Pre-configured Keys. The Pre-configured Keys window appears.
4. Add two entries by clicking on the "+" button:
   • Key: 5A:69:67:42:65:65:41:6C:6C:69:61:6E:63:65:30:39, Byte Order: Normal, Label: ZigbeeAlliance09
   • Key: ab:cd:ef:01:23:45:67:89:00:00:00:00:00:00:00:00, Byte Order: Normal, Label: Nordic Examples

The sniffer can provide additional information. For every packet, you can display channel, RSSI and LQI. The format used for this is configurable in the Interface Options dialog (the gear icon next to the 'nRF Sniffer for 802.15.4'). Depending on the Wireshark version this can be configured in two ways:

1. For Wireshark 3.0 and later: Select "IEEE 802.15.4 TAP".
2. For Wireshark 2.4 and 2.6: Install a custom Lua dissector and select "Custom Lua dissector".

Copy the provided script to the appropriate directory (it can be found in About Wireshark -> Folders -> Personal Lua Plugins). If the directory is not displayed, ensure that the Wireshark was built with Lua support. This can be checked in the About Wireshark window.

The firmware uses the following LEDs to indicate operation:

• PCA10056:
  • LED1 - toggled continuously
  • LED4 - toggled when new frame is received
• PCA10059:
  • green LD1 - toggled continuously
  • blue LD2 - toggled when new frame is received

See the sections below for the description of several known issues with the respective workarounds.

If you have other extcap scripts installed, ensure that they do not send any data to serial ports. For instance, the Nordic BLE sniffer extcap discovers connected BLE sniffers during Wireshark startup by actively sending data to all serial ports. Because Linux applications primarily use advisory locking, there is nothing stopping other applications from opening and writing data to a serial port, causing unexpected behaviour. Currently, the only way to avoid this issue is to disable the offending script by removing the executable permission:

sudo chmod -x <extcap_file>

On some occasions, the ModemManager may send AT commands to the sniffer. To avoid this, use one of the following options:

• Disable ModemManager service:

sudo systemctl stop ModemManager.service
sudo systemctl disable ModemManager.service

• If ModemManager runs on DEFAULT or PARANOID policy, create udev rule:

  Note: The below steps will not work if STRICT policy of the ModemManager is used.

  1. Create new file /etc/udev/rules.d/99-mm-blacklist.rules and include in it the following configuration:

     ACTION!="add", SUBSYSTEM!="usb_device", GOTO="mm_blacklist_rules_end"
     
     ATTR{idProduct}=="154a", ATTR{idVendor}=="1915", ENV{ID_MM_DEVICE_IGNORE}="1"
     
     LABEL="mm_blacklist_rules_end"
     

  2. Apply the new udev rules:

     udevadm trigger

  3. Verify that the settings have been successfully applied:

     udevadm info -q property -n /dev/ttyACMx

     The following values confirm the settings are correctly applied:

     ID_MM_CANDIDATE=0
     ID_MM_DEVICE_IGNORE=1
     

  4. Restart the ModemManager:

     sudo systemctl restart ModemManager

This issue can affect both Ubuntu Linux and Windows.

If you have multiple Python interpreters installed, ensure that pySerial module was installed for the correct Python interpreter used by the extcap script. If that does not help, you may not have sufficient permissions to access the serial device. Please refer to Configuring the system section.

Ensure that the Python installation directory is included in the PATH environment variable and that the correct interpreter with pySerial installed is used.

If during Python installation the Add Python to environment variables option was unchecked, you can add the entry manually by doing the following steps:

1. Open the Control Panel and search for Advanced system settings.
2. Click Environment variables....
3. In System variables window, double click the PATH variable.
4. Append the Python installation directory at the end.

To verify that everything is correct, run:

$ python
Python 2.7.15 (v2.7.15:ca079a3ea3, Apr 30 2018, 16:30:26) [MSC v.1500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import serial

If there are no errors, the configuration was done correctly.