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USB Capture Explanation: Difference Interface vs. Port vs. Endpoint


Hi there,

I am currently trying to sniff some USB traffic from a USB flash drive to a virtual (Ubuntu) machine. But I am confronted with a few understanding problems. Given the following packet (contains every field I am unsure about):

1   0.000000000 host    1.0 USBHUB  64  GET_STATUS Request     [Port 1]
Frame 1: 64 bytes on wire (512 bits), 64 bytes captured (512 bits) on interface 0
Endpoint: 0x80, Direction: IN

So my questions are:

  1. Is the port (indicated with "[Port 1]") the physical port on my machine? And if so: Are they numbered beginning with 0? (So if I have 4 ports, the first one would be 0 and the last one would be 3)

  2. What is the interface then...?

  3. The endpoints are just the indication of the (in case of the mass storage I connected) direction of the access (in this case "IN" -> from host to USB device)

Thanks a lot for your help!

Regards, Rolf


I think I got the thing with the endpoints and interfaces now (please correct me, if I am wrong):

An interface is the logical grouping of several endpoints with the same features.

asked 19 Aug '14, 12:13

Rolf's gravatar image

accept rate: 0%

edited 19 Aug '14, 13:44