Re: config problem - not seeing all messages

[Kurt Buff <kurt.buff () gmail com>]

Others have mentioned switches or hubs for gathering the packets.

Network Taps are another alternative, and many are available used (ebay)
for relatively small prices.
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2499334.m570.l1313&_nkw=network+tap&_sacat=58058

Kurt

On Wed, May 12, 2021 at 4:12 PM Ron W <ronw.mrmx () gmail com> wrote:

> I am trying to use WireShark to diagnose a network problem between a
> Windows PC and a Linux-based controller (for a robot).
>
> The controller uses uboot and TFTP to download the Linux image from the
> PC. Using the controller's serial port, I can see the messages output by
> uboot and by Linux. The messages as as expected and the controller appears
> to work correctly except after downloading Linus via TFTP, the PC
> application is not able to communicate with the controller via TCP/IP.
>
> So, I connected an Ethernet switch between the PC and the controller and
> also connected a laptop to the switch so I can monitor with WireShark.
>
> What I see in WireShark's capture log (see attached screen picture) would
> have made sense, but the log is not showing the TFTP messages. So, to make
> sure TFTP was actually working, I interrupted uboot before it started
> downloading Linux. I then entered commands to have uboot download various
> test files I created and inspect what was downloaded to make sure the
> expected content was in the controller. As I did this, I continued to
> monitor with WireShark. Still I did not see anything after the initial ARP
> request from the controller, asking for the MAC corresponding to the IP
> address of the PC. i did not even see an ARP reply from the PC.
>
> Since I'm not seeing the TFTP messages, nor the PC's ARP response, I have
> to assume I configured WireShark incorrectly. Looking at my capture
> selection and capture options (see attached screen pictures), I can't find
> anything to explain not seeing the TFTP messages in the capture log.
>
> I even tried a fresh install of WireShark on another laptop that had never
> had Wireshark on it. Same result: No TFTP message in the capture log.
>
> I have used WireShark successfully in the past. As best I can remember, I
> setup WireShark the same as I have in the past.
>
> Still, I must be doing something wrong. Any advise on what I need to fix
> in my WireShark settings?
>
> Thanks in advance
>
> ___________________________________________________________________________
> Sent via:    Wireshark-users mailing list <wireshark-users () wireshark org>
> Archives:    https://www.wireshark.org/lists/wireshark-users
> Unsubscribe: https://www.wireshark.org/mailman/options/wireshark-users
>              mailto:wireshark-users-request () wireshark org
> ?subject=unsubscribe
___________________________________________________________________________
Sent via:    Wireshark-users mailing list <wireshark-users () wireshark org>
Archives:    https://www.wireshark.org/lists/wireshark-users
Unsubscribe: https://www.wireshark.org/mailman/options/wireshark-users
             mailto:wireshark-users-request () wireshark org?subject=unsubscribe