On Thu, 31 Jan 2019 07:41:38 -0800, Richard Cochran wrote:
> FWIW, Wireshark shows "Bad FCS" for this frame.  Please fix it at the
> sender.

To be fair, this is just an artifact of Wireshark guessing wrong on the
packet structure. AFAIK there's no indication of the frames having FCS or
not in pcap. Wireshark has to guess and when it sees the packet being
6 bytes longer than the payload and 64 bytes in total, it's natural to
guess it's 2 bytes padding and 4 bytes FCS to satisfy the Ethernet
minimum length requirements.

While in fact, I expect that the FCS got stripped and the frame was
68 bytes. The real FCS was most likely correct.

Seeing the padding bytes not being zero, I cannot resist wondering what
part of its memory is the sender leaking. Could the leak be used to
gather some interesting data? ;-)

In any case, this behavior is wrong on several levels. And with the
likely security issue present, I don't think it's worth the time to
consider this hardware seriously.

 Jiri


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