Wireshark · Wireshark-users: Re: [Wireshark-users] Decoding packets from a Cisco's "ip traffic-export" flow

["Frank Bulk" <frnkblk@xxxxxxxxx>]

I used bittwiste to remove the first 12 bytes of the attached packet capture
that included a variety of traffic, and you'll see that some packets are
fine, but others, such as 4, 7, 8, etc are not.

Can anyone make sense of it?

Regards,

Frank

-----Original Message-----
From: Bill Meier [mailto:wmeier@xxxxxxxxxxx] 
Sent: Saturday, March 01, 2008 12:13 PM
To: frnkblk@xxxxxxxxx; Community support list for Wireshark
Subject: Re: [Wireshark-users] Decoding packets from a Cisco's "ip
traffic-export" flow

Frank Bulk wrote:
>
> Ethernet hdr specifying type  0x0800 [IP]
> 0000  00 12 79 63 1a 8c 00 30  b6 53 00 06 08 00
>
> 20 unknown (to me) bytes
> 0000                                             b6 53
> 0010  00 08 00 01 4a 9e 0e 06  88 64 11 00 00 06 00 3e
> 0020  00 21
>
> looks like a good ip hdr & icmp payload
> 0020        45 00 ....................................
> 0030  ................................................
> 0040  ................................................
> 0050  ............................................
>
>

OK: (Learning as I go)

It turns out that it appears that what's really going on is that there's
an extra 12 bytes of ethernet destination/source at the beginning of the
packet.

If I strip those, I get what appears to be the original frame (see
attached).

So: I it seems that the ethernet src/dest at the beginning is (as you
said) the MAC of the switch tap src and (presumably) the dest is the MAC
of your wireshark PC.

Interesting....

Attachment: bittwiste_output.pcap
Description: Binary data

Attachment: ip_traffic-export(more).pcap
Description: Binary data