Re: DLT for Bluetooth Low Energy

[Guy Harris <guy () alum mit edu>]

On Jun 13, 2013, at 7:24 PM, Mike Ryan <mikeryan () lacklustre net> wrote:

> Hi, I impelemented most of the BTLE support in Ubertooth.
>
> > So do LINKTYPE_BLUETOOTH_LE_LL/DLT_BLUETOOTH_LE_LL packets include the
> > preamble octet and the CRC?
>
> They include the 3 octet CRC, they do not include the preamble.

OK, I'll update the description on the "link-layer header types" page to note that.

So the packet in the file has:

        4 bytes of Access Address;

        2-39 bytes of packet data;

        3 bytes of CRC;

in sequential order, with nothing separating them, right?

> To validate the CRC you must know a per-connection CrcInit. This value
> will be stored in the PPI with each packet.

"Stored in the PPI"?  Does that mean "stored in per-packet information kept by the program reading the capture file", 
or does it mean "per-packet information stored *in* the capture file"?  If the latter, that presumably means there's 
some form of pseudo-header preceding the Access Address.

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