R: [chrony-users] Checking chrony daemon status via NTP3 protocol

[SALA MASSIMO <MASSIMO.SALA@xxxxxxxxx>]

Hi Miroslav

I use chrony 3.5 on Centos 6.10, linux 2.6.32-754.29.2.el6.x86_64.
I compiled chrony from sources with gcc version 7.3.1 20180303 (Red Hat 7.3.1-5) (GCC)

The servers are VM guests under HyperV.
Pls see the configuration.

I send you also our simplified POC test.


Many thanks for your attention, Massimo

________________________________________
Da: Miroslav Lichvar <mlichvar@xxxxxxxxxx>
Inviato: mercoledì 27 maggio 2020 08:53
A: chrony-users@xxxxxxxxxxxxxxxxxxxx
Oggetto: Re: [chrony-users] Checking chrony daemon status via NTP3 protocol

On Tue, May 26, 2020 at 05:49:15PM +0000, SALA MASSIMO wrote:
> Hi
>
> I apologize in advace if my question is trivial.
>
> The daemon is stopped (ver 3.5).
> I start it and send a NTP3 CLIENT query, to localhost port 123/udp:
>     NTP_VERSION << 3 | NTP_MODE_CLIENT
>
> The first answer has the status 0xdc : the bit NTP_LEAP_NOTSYNC is set.
> Good: the daemon is starting and looking for the Ntp servers.
>
> I query again the daemon, and in the following replies from the server:
> * the status is OK : 0x1c
> * the  server time (reference timestamp, at offset 16 of the Udp packet payload) is incorrect.

This sounds like a bug. In a quick test with the current development
code and chrony-3.5 I didn't see this behavior.

How is your server configured?

--
Miroslav Lichvar


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Prima di stampare, pensa all’ambiente.

Attachment: chrony.conf
Description: chrony.conf

#!/usr/bin/env python

import sys, socket, struct, time

NTP_VERSION = 3
NTP_MODE_CLIENT = 3
NTP_TS_REFERENCE_OFS = 16       # reference timestamp
UNIX_EPOCH = 2208988800

if len(sys.argv) == 1 :
	sys.exit("Usage: ntp_test.py <host>")

host = sys.argv[1]
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.settimeout(5)

payload = chr((NTP_VERSION << 3) | NTP_MODE_CLIENT) + 47 * chr(0)
s.connect((host, 123))
while True :
	s.send(payload)
	resp = s.recv(4096)
	if resp :
		#print "rx", len(resp), repr(resp.replace('\0', '.'))
		t = struct.unpack(">I4", resp[NTP_TS_REFERENCE_OFS : NTP_TS_REFERENCE_OFS + 4])[0]
		print t - UNIX_EPOCH
	time.sleep(1)