[ntp:questions] ntp-client does not sync with server

Stefan K shadow_7 at gmx.net
Thu Mar 21 14:52:46 UTC 2019


Hello,

today I've to spend a little bit time for this, here are the tcpdump results, it looks good to me:
#client ask:
Network Time Protocol (NTP Version 4, client)
    Flags: 0xe3, Leap Indicator: unknown (clock unsynchronized), Version number: NTP Version 4, Mode: client
    Peer Clock Stratum: unspecified or invalid (0)
    Peer Polling Interval: 6 (64 sec)
    Peer Clock Precision: 0.000000 sec
    Root Delay: 0 seconds
    Root Dispersion: 0 seconds
    Reference ID: (Initialization)
    Reference Timestamp: Jan  1, 1970 00:00:00.000000000 UTC
    Origin Timestamp: Jan  1, 1970 00:00:00.000000000 UTC
    Receive Timestamp: Jan  1, 1970 00:00:00.000000000 UTC
    Transmit Timestamp: Mar 21, 2019 14:23:59.184649604 UTC

#server answer:
Network Time Protocol (NTP Version 4, server)
    Flags: 0x24, Leap Indicator: no warning, Version number: NTP Version 4, Mode: server
    Peer Clock Stratum: secondary reference (3)
    Peer Polling Interval: 6 (64 sec)
    Peer Clock Precision: 0.000000 sec
    Root Delay: 0.00921630859375 seconds
    Root Dispersion: 0.020660400390625 seconds
    Reference ID: 129.70.132.35
    Reference Timestamp: Mar 21, 2019 14:23:51.562362183 UTC
    Origin Timestamp: Mar 21, 2019 14:23:59.184649604 UTC
    Receive Timestamp: Mar 21, 2019 14:23:59.170848067 UTC
    Transmit Timestamp: Mar 21, 2019 14:23:59.170907972 UTC

At the moment I tried it with debian stretch as server, but the problem is the same :(


On Monday, March 18, 2019 5:18:32 PM CET Mike Cook wrote:
> I don’t have these versions but I would suspect some DNS/routing issue. Have you tried tcpdump or other packet tracing to see if you are getting any ntp packets back. 
> Your nmap response has an ip resolution for  timeserv.domain.ag as 194.94.xxx.xxx but this net dress is not used in the working config. 
> 
> 
> 
> > Le 11 mars 2019 à 12:38, Stefan K <shadow_7 at gmx.net> a écrit :
> > 
> > nobody an idea?
> > 
> > 
> > 
> > On Tuesday, March 5, 2019 9:11:54 AM CET Stefan K wrote:
> >> Hallo,
> >> 
> >> we have our own ntp-server which is running Ubuntu 14.04.LTS.
> >> This Server works fine:
> >> ntpq -pn
> >>     remote           refid      st t when poll reach   delay   offset  jitter
> >> ==============================================================================
> >> *178.63.9.110    129.69.1.153     2 u   56  128  377   22.658    0.249   0.053
> >> -85.214.38.116   192.53.103.108   2 u   54  128  377    2.101   -5.105   0.051
> >> +37.58.57.238    192.53.103.103   2 u   50  128  377   20.971    0.839   0.114
> >> +94.130.76.108   192.53.103.108   2 u   56  128  377   24.007   -1.009   0.163
> >> 
> >> 
> >> But on our Debian Strech server they all got Stratum16 and doesn't sync:
> >> ntpq -p
> >>     remote           refid      st t when poll reach   delay   offset  jitter
> >> ==============================================================================
> >> timeserv.domain.ag .INIT.          16 u    - 1024    0    0.000    0.000   0.000
> >> 
> >> 
> >> In Debian Jessie (and the same configuration/network) it works fine and get a Stratum3, also an 'ntpdate timeserv.domain.ag' works on Debian Stretch.
> >> 
> >> The firewall is not a problem, because with nmap and ntp-script it works fine:
> >> nmap -sU -p 123 --script ntp-info timeserv.domain.ag
> >> 
> >> Starting Nmap 7.40 ( https://nmap.org ) at 2019-02-26 09:25 CET
> >> Nmap scan report for timeserv.domain.ag (194.94.xxx.xxx)
> >> Host is up (0.00017s latency).
> >> PORT    STATE SERVICE
> >> 123/udp open  ntp
> >> | ntp-info: 
> >> |   receive time stamp: 2019-02-26T08:26:05
> >> |   version: ntpd 4.2.6p5 at 1.2349-o Fri Jul  6 20:19:54 UTC 2018 (1)
> >> |   processor: x86_64
> >> |   system: Linux/3.13.0-161-generic
> >> |   leap: 0
> >> |   stratum: 3
> >> |   precision: -20
> >> |   rootdelay: 31.589
> >> |   rootdisp: 42.723
> >> |   refid: 178.63.9.110
> >> |   reftime: 0xe01f73ce.3608c5f7
> >> |   clock: 0xe01f768f.e9bd2105
> >> |   peer: 57654
> >> |   tc: 10
> >> |   mintc: 3
> >> |   offset: 0.008
> >> |   frequency: 27.593
> >> |   sys_jitter: 1.020
> >> |   clk_jitter: 0.180
> >> |_  clk_wander: 0.014\x0D
> >> Service Info: OS: Linux/3.13.0-161-generic
> >> 
> >> Nmap done: 1 IP address (1 host up) scanned in 13.75 seconds
> >> 
> >> and it also looks like that the client try to query the tnp-server because I can find the IP-Address of the Server under the section 'private clients':
> >> nmap -sU -pU:123 -Pn -n --script=ntp-monlist timeserv.domain.ag
> >> 
> >> Can somebody help me with this issue?
> >> 
> >> Thanks in advance!
> >> 
> >> best regards 
> >> Stefan
> >> 
> >> 
> >> _______________________________________________
> >> questions mailing list
> >> questions at lists.ntp.org
> >> http://lists.ntp.org/listinfo/questions
> >> 
> > 
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> 
> 



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