'ntptest' - Check NTP server

ntptest is a command line utility that can be used to query the current time and status from an NTP server. The data fields of the response packet from the server as well as the fields from the request packet sent to the server are displayed in detail, so this is very useful to see which data an NTP server sends to its clients.

This program needs to be run in a command line / terminal window (cmd.exe on Windows).

Just run the program by typing

ntptest <hostname>

where, of course, <hostname> has to be replaced by the DNS name or IP address of the NTP server to be queried. The command

ntptest -?

shows some usage information including the command line options that can be used to define the exact behavior.

If ntptest is called with the -Z option, it sends 4 requests/sec to the server, and the initial time offset is compensated, so you can even see how the offset develops over time:

ntptest -Z <hostname>

The output is something like:

ntptest v1.10, (c) Meinberg 2014-2018, contact: <martin.burnicki@meinberg.de>

Host <hostname>, running continuously
Initial time offset -0.000169012 will be compensated
2018-11-08 09:33:16.640653559, st 1, leap 0, offs[ms]: +0.115
2018-11-08 09:33:16.891949683, st 1, leap 0, offs[ms]: +0.131
2018-11-08 09:33:17.143102303, st 1, leap 0, offs[ms]: +0.113
2018-11-08 09:33:17.394358585, st 1, leap 0, offs[ms]: +0.126
...

If you run the program against an NTP server while the server handles a leap second, you can observe how the server adjusts the leap bits, or if the server smears the time to hide the leap second from its clients.

Here is an executable program for Windows. The ZIP archive has been updated and now contains an openSSL DLL that was missing from an earlier version. The DLL is required to support symmetric keys:

• https://www.meinberg.de/download/source/ntptest-1.11-win-exe+dll.zip

And the source code for Windows:

• https://www.meinberg.de/download/source/ntptest-1.11-win.zip

Source code for Linux or FreeBSD:

• https://www.meinberg.de/download/source/ntptest-1.11-unix.tar.gz

Public git repo of the source code:

• https://git.meinbergglobal.com/utilities/ntptest.git/

• Return specific exit codes in case of error, and list the valid exit codes in the usage information.
• Support building against openSSL v1.1.1.

• Support symmetric MD5 keys.
• Configurable number for request packet mode.
• Print request packet even if no response was received.
• Support build on FreeBSD.

• Don't print min/max results after single query.

• Improved printing of refid.

— Martin Burnicki martin.burnicki@meinberg.de 2019-09-04