usbrply

Convert a .pcap file (captured USB packets) to Python or C code that replays the captured USB commands.

Supported packet sources are: * Linux Wireshark (via usbmon) * Windows Wireshark (via USBPcap)

Supported output formats are: * libusb Python (primary) * (libusb C: fixme) * (Linux Kernel C: fixme) * JSON

Example applications: * Rapidly reverse engineer and re-implement USB protocols * Record a proprietary Windows programming sequence and replay on an embedded Linux device * Snoop USB-serial packets

Questions? Please reach out on github or join #usbrply on Freenode IRC

Linux installation

# Do one of these
# Easier to setup, but slower
sudo pip install python-pcapng
# Much faster, but no longer maintained
sudo apt-get install -y python-libpcap
git clone https://github.com/JohnDMcMaster/usbrply.git
cd usbrply
sudo python setup.py install

Windows installation

There is probably an easier way to do this but this is what I got to work. Tested on Windows 7 x64

Setup python and pip * Get the latest Python 3 release (https://www.python.org/downloads/) * I used Python 3.7.8 (Windows x86-64 executable installer) * Keep default setup options (in particular this will install pip)

Install * Open a command prompt * Default should be your home dir (ex: C:\Users\mcmaster) * python -m venv usbrply * usbrply/Scripts/activate.bat * pip install usbrply

Test * If not still in venv (prompt like "(usbrply)" ): usbrply/Scripts/activate.bat * python usrply\Scripts\usbrply -h * You should get a help message * Download and place in your home dir: https://github.com/JohnDMcMaster/usbrply-test/raw/master/win1.pcapng * python usrply\Scripts\usbrply win1.pcapng * You should see python code that will reproduce the .pcap file commands

Sample workflows

Sample workflow for capturing Windows traffic and replaying traffic in Python: * Install Wireshark. Make sure you install the USBPcap library * Start Wireshark * Connect USB device to computer * Start catpure * Start your application, do your thing, etc to generate packets * Close application * Stop capture * Save capture. Save in pcap-ng format (either should work) * Close Wireshark * Run: "usbrply --device-hi -p my.pcapng >replay.py" * Linux: run "python replay.py" * Verify expected device behavior. Did an LED blink? Did you get expected data back?

Sample workflow for capturing Windows VM traffic from Linux host and replaying traffic in Python: * Example: program a Xilinx dev board under Linux without knowing anything about the JTAG adapter USB protocol * Linux: Install Wireshark * Linux: Enable usbmon so Wireshark can capture USB (sudo modprobe usbmon, see http://wiki.wireshark.org/CaptureSetup/USB) * Linux: Boot Windows VM (ie through VMWare) * Linux: Start Wireshark. Make sure you have USB permissions (ie you may need to sudo) * Connect USB device to computer * Linux: use lsusb to determine which device bus is on. Try to choose a bus (port) with no other devices * Linux: start catpure on bus from above * Linux: attach USB device to Windows guest * Windows: start your application, do your thing, etc to generate packets * Linux: stop capture * Linux: save capture. Save in pcap-ng format (either should work) * Linux: run: "usbrply --device-hi -p my.pcapng >replay.py" * Linux: detatch USB device from Windows guest * Linux: run "python replay.py" * Verify expected device behavior. Did an LED blink? Did you get expected data back?

You may need to filter out USB devices. There are two ways to do this: * --device-hi: use the last device enumerated. This works well in most cases, including FX2 renumeration * --device DEVICE: manually specify the USB device used. Get this from lsusb output or Wireshark view

Other useful switches: * --rel-pkt: intended to easier allow diffing two outputs. Ex: what changed in trace for LED on vs LED off? * --no-packet-numbers: alternative to above * --fx2: decode common FX2 commands (ex: CPU reset) * --range RANGE: only decode a specific packet range. Use along with Wireshark GUI or refine a previous decode * see --help for more

Version history

v0.0.0 * Crusty C++ program

v0.0.1 * Crusty python program

v1.0.0 * Seperate parsing from printing * Windows data source officially supported

v2.0.0 * JSON: packn moved to new "submit" and "complete" entries * JSON now has raw urb structures (added to submit/complete) * python3 support * libpcapng support

v2.0.1 * Fix packaging issues

v2.1.0 * python2 support officially removed * VID/PID filter fixed * Windows pip install instructions * Linux: basic interrupt support * General interrupt cleanup / fixes * Better logging for dropped packets * --no-packet-numbers: line numbers line up vs --packet-numbers

v2.1.1 * Fixme pip README

JSON output

use -j switch to output a parsing intermediate representation that should resemble original USB requests along with associated metadata. This can be used in more advanced applications, such as if you need to decode a complicated protocol or convert USB output to higher level API calls. An example can be found here: https://github.com/ProgHQ/bpmicro/blob/master/scrape.py This example first aggregates USB packets into application specific packets, and then decodes these into API calls

USB serial decoder

usbrply-serial supported adapters: * FT2232C: data rx/tx

TODO: write doc