Ethereal-users: RE: [Ethereal-users] Trying to measure CRC errors..

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From: "Johnny Choque" <jchoque@xxxxxxxxxxxxxxx>
Date: Fri, 14 Mar 2003 09:56:26 +0100
Firstly, you must hack the network card's driver. In Linux is relatively
easy if you know the network card's code. I have made some hacking in the
orinoco driver of wireless card Lucent Orinoco 802.11b and then I have
captured the packets with bad CRC.

Johnny

> -----Mensaje original-----
> De: ethereal-users-admin@xxxxxxxxxxxx
> [mailto:ethereal-users-admin@xxxxxxxxxxxx]En nombre de Guy Harris
> Enviado el: jueves, 13 de marzo de 2003 19:54
> Para: cplusplus@xxxxxxxxx
> CC: ethereal-users@xxxxxxxxxxxx
> Asunto: Re: [Ethereal-users] Trying to measure CRC errors..
>
>
> 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.
>
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