Wireshark-users: Re: [Wireshark-users] Capturing and merging files from different machines

From: Jeff Morriss <jeff.morriss.ws@xxxxxxxxx>
Date: Wed, 18 Jun 2008 11:44:45 -0400


Chris Swinney wrote:
Hi,

I have taken a capture on two different machines from an in-line network tap (one to capture upstream, one to capture downstream data). I now need to merge these file, but when I ask Wireshark to merge them chronologically, it seems to merge them based on the initial time taken into the capture, not the actual capture time.

I have tried to mitigate time differences by synching both machines to an NTP server, but of course both captures are themselves started a different times. How can I best accomplish what I want? I�ve had a look at mergecap (as well as the inbuilt merge facility as shown above), but am not sure if this will still do what I�m after.

Maybe I'm being naive here but I would expect a "chronological merge" to merge the packets based on their (absolute) timestamps (that is, based on the time stamp of each packet--which is in secs+usecs since the epoch), not based on seconds since the beginning of the capture file.

(In fact I merge capture files quite frequently so I somewhat depend on this functionality.)

Questions:

- what version of Wireshark are you using?
- what is your time display format (time of day, seconds since beginning of capture, etc.)? Not that it should matter, but...