Wireshark-users: Re: [Wireshark-users] Dump file format?
From: Sake Blok <sake@xxxxxxxxxx>
Date: Tue, 15 Apr 2008 07:20:35 +0200
On Mon, Apr 14, 2008 at 09:26:59PM -0700, Trevor Bosaw wrote:
> Hey,
> 
> I have been examining data from a group that saves their packet data  
> in a dump file.  Wireshark recognizes these dump files, but they are  
> too large, and it crashes before it can finish reading in the entire  
> file.  I have been able to split the files using the Unix command  
> 'split', but since this command obviously cannot read the dump format,  
> it splits the file in the middle of a packet.

Since the pcap file has a "file-header" and a per-packet "packet-header"
you can't just split it, because the last packet of the first file
will be split in the middle of a packet. But more importantly, the
second file will have no "file-header".

Use "editcap" instead, it is distributed with Wireshark, see:

http://www.wireshark.org/docs/man-pages/editcap.html


> Does anyone know what the wireshark dump file format is, and if so, if  
> it's possible that I can manually open the second and on portions of  
> the dump file, delete the second part of the packet, and load the rest  
> into wireshark?

The file format Wireshark uses is the "libpcap" format, see:

http://wiki.wireshark.org/Development/LibpcapFileFormat

Hope this helps,
Cheers,
    Sake