Capture the communications between 2 USB connected devices

You can capture USB communications in three fundamentally different ways, depending on what exactly you need: software sniffing, host-side event tracing, or true hardware man‑in‑the‑middle sniffing. The right method depends on whether you want high‑level URBs, low‑level USB packets, or full electrical‑layer capture.

🧩 Core takeaway

To capture traffic between two USB devices, you must place something in the middle — either a software monitor on the host (Linux usbmon, Windows USBPcap/ETW), or a hardware USB protocol analyzer (e.g., OpenVizsla). Software tools can only see traffic between the host and a device, not between two peripherals directly.

🛠️ 1. Software USB sniffing (host sees both devices)

This works only if both devices are connected to the same host computer. The host can observe all URBs and transfers.

Linux: usbmon + Wireshark
Linux supports raw USB capture via usbmon, which Wireshark can decode.
Wireshark’s USB capture documentation confirms this capability.

Workflow:

Load usbmon: sudo modprobe usbmon

Capture from usbmon0 (all buses) or usbmonX (specific bus)

Open Wireshark → Capture → Interfaces → usbmonX

Pros:

Free, powerful, detailed URB-level capture

Works with any USB device class

Cons:

Cannot capture true low-level packets (token/handshake) — only URBs

Only works when both devices communicate through the host

Windows: USBPcap or ETW tracing
Windows supports USB tracing via USBPcap (used by Wireshark) and ETW tracing using Logman.
Microsoft’s documentation shows how to capture USB driver stack events.

Workflow (ETW example):

cmd

logman create trace -n usbtrace -o %SystemRoot%\Tracing\usbtrace.etl -nb 128 640 -bs 128
logman update trace -n usbtrace -p Microsoft-Windows-USB-USBXHCI
logman start -n usbtrace

Pros:

Built into Windows

Good for debugging enumeration, driver issues

Cons:

Not full protocol-level capture

More complex to decode than Wireshark

🔌 2. Hardware USB protocol analyzers (true MITM)

If you need to capture device-to-device communication (e.g., two USB devices talking through a USB host, or a USB host and device where you want electrical-level packets), you need a hardware sniffer.

Wireshark’s USB capture page lists hardware options.

Examples:

OpenVizsla (open-source USB 2.0 analyzer)

Total Phase Beagle USB 12/480/5000 analyzers

LeCroy USB analyzers (high-end)

Pros:

True man‑in‑the‑middle capture

Shows low-level packets (token, data, handshake)

Works even when no OS is involved

Cons:

Costs $100–$5,000 depending on capability

Requires physical insertion between devices

🔄 3. USB “tap” cables or DIY MITM boards

Wireshark’s documentation mentions simple MITM hardware setups.

You can build a USB tap using:

A microcontroller with USB OTG + sniffing firmware

FPGA-based USB PHY breakout

Differential pair tap + high-speed logic analyzer (only for USB 1.1/low-speed)

These are more advanced and require electrical knowledge.

🧠 Which method should YOU use?

Here’s how to choose:

Your scenario Best method
Two USB devices both plugged into your PC Linux usbmon or Windows USBPcap/ETW
You need full protocol-level packets Hardware analyzer (OpenVizsla / Beagle)
Devices communicate without a PC (embedded host) Hardware analyzer only
You’re debugging enumeration or driver issues Windows ETW or Wireshark usbmon

🔍 One important limitation

Software sniffers cannot capture traffic between two peripherals directly (e.g., USB flash drive ↔ USB printer). USB always requires a host, and software sniffers only see host ↔ device traffic.

If you need to observe traffic between devices, you must sniff the host’s traffic or use hardware MITM.

Want me to help you pick the exact hardware or walk you through the setup?

Tell me:

What two devices you’re trying to monitor

Whether a PC is involved

Whether you need URB-level or electrical-level packets

I can give you a precise, step-by-step workflow tailored to your setup.

✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦ ✦

https://wiki.wireshark.org/CaptureSetup/USB

https://learn.microsoft.com/en-us/windows-hardware/drivers/usbcon/how-to-capture-a-usb-event-trace

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