| [chrony-users] Seeking assistance deciphering NTP packet capture |
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- To: "chrony-users@xxxxxxxxxxxxxxxxxxxx" <chrony-users@xxxxxxxxxxxxxxxxxxxx>
- Subject: [chrony-users] Seeking assistance deciphering NTP packet capture
- From: Bryan Evenson <bevenson@xxxxxxxxxxxxxx>
- Date: Fri, 3 Jun 2022 19:43:07 +0000
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- Thread-topic: Seeking assistance deciphering NTP packet capture
All,
I'm using chrony version 4.1 on an embedded Linux system. I have an automated test that is checking various operations on my device, including NTP. Chrony is correctly setting and syncing time with the provided NTP source, but the automated test is failing. The test is analyzing the packet capture and thinks that chrony never syncrhonizes with the NTP source. I'm looking at the packet capture in Wireshark and I'm seeing some odd timestamps. I'm wondering if someone can help explain what is happening.
Prior to the test, I set my DUT system time off by about an hour and a half.. About a minute into testing chrony did update the device's time to the correct time (validated from the device's display). However, I'm not seeing anything close to the current time in the "Transmit Timestamp" field for the NTP client packets chrony is sending. According to Wireshark, the "Transmit Timestamp" was the following values in successive packets:
March 20, 1985 7:17:35 UTC
July 31, 2036 00:19:20 UTC
July 25, 2004, 05:41:48 UTC
Feb 16, 2061 19:03:36 UTC
These were from packets send about one minute apart from each other. On the server response, the Reference Timestamp, Receive Timestamp and the Transmit Timestamp were all reasonably close to each other and were based on current time.
Does someone know why the transmit timestamps are so far off from actual time? Is this just a data translation problem where Wireshark is reading the field format incorrectly?
Thanks,
Bryan
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