[Guy Harris <guy@xxxxxxxxxx>]

On Thu, Mar 13, 2003 at 07:48:13PM +0100, cplusplus@xxxxxxxxx wrote:
>          I would like to sniff my network and find out about CRC
>          errors and such. How can i catch these packets?

	http://www.ethereal.com/faq.html#q5.26

	http://www.ethereal.com/faq.html#q5.27

In general, you can't, at least not with Ethereal.  Some commercial
sniffers for Windows have their own device drivers and can capture
packets with errors; the drivers for at least some network interfaces on
some versions of UNIX (some of the BSDs, at least; it's harder to do
that on Linux, because the packet capture mechanism in the OS is part of
the networking stack) might supply packets with CRC errors and/or supply
the CRC as part of the packet, but

	1) they might not supply the CRC even though they supply packets
	   with CRC errors;

	2) they don't supply a flag indicating which packets have CRC
	   errors;

	3) Ethereal has no way of knowing whether the CRC was supplied
	   or not, and just treats it as a packet trailer.