I was interested in testing my USB cables that I know work, but wanted to see if they had any retransmission going on.

Then today, I found out Linux has a kernel module that allows you to “monitor” usb interfaces. Like… using wireshark.

I won’t explain how to set up wireshark for your distro, that’s for you to figure out.

Once you have wireshark set up, you just sudo modprobe usbmon then lsusb. Find the USB interface you want to monitor in the list, then select it when starting wireshark (gui).

That’s about it… you can filter like this:

usb.urb_status != 0 && !(usb.urb_status == -115)

Short post, but hope this helps you test your own USB cables for any errors that aren’t shown in dmesg, like failed packets.