Having no luck monitoring NTP

asked 2026-04-06 18:34:05 +0000

Hello. I am working on an IoT device based on an Adafruit Feather with a Wiznet W5500 Ethernet breakout board. It is running an SNTP client that only gets a response for its first request. I am trying to use Wireshark to figure out what is going on but am not getting any output related to the device.

I have tried:

port 123 capture filter
ip.host display filter
ethernet filters

The port 123 filter did capture an NTP request/response from my Mac.

Environment:

MacPro, MacOS 15.5
Wireshark 4.6.4
The Mac and the Feather are plugged into the same Ethernet switch

Note that Wireshark does not capture either the request or the response for the first request.

I know that the W5500 is functional because I do get a response first request and at startup the device also makes an HTTP request and gets and displays the response as expected.

TIA, D.

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Thanks! I completely forgot about ow things are when on a switch instead of a hub. Now I just have to find a hub that will work with both my Mac and the IoT device. Wish me luck. 🤣

dpatterson ( 2026-04-06 23:31:05 +0000 )edit

Or purchase a relatively inexpensive TAP or switch with port monitoring capability? Examples:

See also the following (although some information may be old/obsolete):

cmaynard ( 2026-04-08 14:55:15 +0000 )edit

Thanks for the additional info. Wow. midBit doesn't give their taps away, do they? I'll read up on the Netgear and see if I can figure out port monitoring works. Thanks again.

dpatterson ( 2026-04-10 00:10:35 +0000 )edit

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