Wireshark-users: Re: [Wireshark-users] TCP keep -alives

From: Stephen Fisher <stephentfisher@xxxxxxxxx>
Date: Thu, 16 Nov 2006 14:59:04 -0800
On Thu, Nov 16, 2006 at 07:41:41AM -0800, imfaus wrote:

> From parsing through the documentation, I did'nt see any explanation 
> on keep-alives or how wire shark knows the TCP packet is in fact a 
> "keep-alive" packet. I have a particular capture and I am lead to 
> believe that there might be some keepalives, but I was curious. Does 
> the tool look for a payload of 1 (in the TCP header) and a sequence 
> number that is nonincrementing to determine if in fact the packet is a 
> keep-alive packet?

I'm not sure how the keep-alives are detected without looking at the 
code.  TCP Keepalives show up in the Info column and can be seen by 
using this display filter: tcp.analysis.keep_alive


Steve