Wireshark-users: Re: [Wireshark-users] Reassemble packets from Gnutella download?
From: "Small, James" <[email protected]>
Date: Sat, 3 Feb 2007 15:20:19 -0500

You should be able to do a follow TCP stream and save the contents to a file.  However, in order to edit the file, you need to use a hex editor.  If you use a regular editor, it will mangle the file.  Usually when I do this (for example saving a JPEG), I open a working JPEG in a Hex editor so I can see what the initial file header is.  For JPEGs, I believe this is HEX:ffd8ffe000104a464946 (ASCII:ÿØÿà..JFIF).  Then when I edit the exported TCP stream, I know to delete up to that header so that I can save a valid JPEG.  I have used this to extract many different types of files successfully.

Here's an example free Hex Editor that I have used:

Not to say there aren't better ones, but this one has worked for me.

From: [email protected] [mailto:[email protected]] On Behalf Of d a
Sent: Saturday, February 03, 2007 11:47 AM
To: [email protected]
Subject: [Wireshark-users] Reassemble packets from Gnutella download?

Hello all,

I posted a couple days ago and it never made the forum so I appologize if this is a repeat.
First off...great software!
I have about 12 hours of Wireshark use so far. Having trouble reassembling packets downloaded from Gnutella. I can reassemble HTTP image packets n/p. Someone please tell me what Im doing wrong.

I begin a capture (wireshark latest realease), download an image file (jpg ) with only 1 host (to avoid swarming downloads). I then stop the capture and filter using the "ip.source" filter. I can then view all tcp packets downloaded from the host and checksum shows successful. I dont get the same options as I do with a HTTP Jpeg download and cant find an option to export as raw data. I even tried "follow TCP stream", stripping header info, and copy and paste the bytes to a  text editor with a JPEG extension but the image wont open. I do have TCP dissector and IP reassemble ticked. Maybe Im using the wrong filter?

    Any suggestions as to how I can reassemble an image file downloaded from with Gnutella would be greatly appretiated.

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