Wireshark-dev: Re: [Wireshark-dev] Dissecting - access previous packet in TCP conversation

From: Stephen Fisher <steve@xxxxxxxxxxxxxxxxxx>
Date: Tue, 23 Nov 2010 12:32:03 -0700
On Tue, Nov 23, 2010 at 12:20:26PM -0700, Stephen Fisher wrote:

> If you need to keep a running tab of what the last packet's value was, 
> you can save the current packet's (from the correct direction) in the 
> per conversation data and then replace it on every new packet you 
> dissect so you always have the latest value.  Per conversation is 
> probably more often used to set certain values for later use though.

It would probably help to point out that the first time wireshark opens 
a capture file (or does a live captuer), it dissects the packets in 
sequential order.  After that, there is no guarantee of the order in 
which a user will click on packets (packets are re-dissected when a user 
clicks on them.)  Therefore, my suggestion of keeping a running tab 
would only work on the first pass.  This is where using per-conversation 
and per-packet data comes in handy.