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I am trying to setup local NTP server for some testing. I have installed NTP on Ubuntu 18.04 and commented server-pool block in the config file

Here is the full config : 

driftfile /var/lib/ntp/ntp.drift

leapfile /usr/share/zoneinfo/leap-seconds.list

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

restrict -4 default kod notrap nomodify nopeer noquery limited
restrict -6 default kod notrap nomodify nopeer noquery limited

restrict 127.0.0.1
restrict ::1

restrict source notrap nomodify noquery

restrict 10.24.0.0 mask 255.255.0.0 notrust

server 127.127.1.0
fudge 127.127.1.0 stratum 10

Used this command to set the time I want sudo timedatectl set-time "2013-06-02 23:26:00"

I also tried to see if service is ntp service is running by sudo systemctl status ntp.service which is running, but when grepped on port 123 I didn't find anything running. Found with ps

ubuntu@ntp:~$ ps auxww | grep '[n]tp'
ntp      13517  0.0  0.8 103212  4136 ?        Ssl  Jun02   0:00 /usr/sbin/ntpd -p /var/run/ntpd.pid -g -u 111:115

When client tries to get time from NTP running on this server, it timeouts. Also Dont see any messages in /var/log/syslog

More info :

ubuntu@ntp:~$ ps auxww | grep '[n]tp'
ntp        807  0.0  0.7 103212  3480 ?        Ssl  Jan28   0:02 /usr/sbin/ntpd -p /var/run/ntpd.pid -g -u 111:115

ubuntu@ntp:~$ ntpq -pn
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*127.127.1.0     .LOCL.          10 l    2   64  377    0.000    0.000   0.000

ubuntu@ntp:~$ ntpq -c rv
associd=0 status=0515 leap_none, sync_local, 1 event, clock_sync,
version="ntpd [email protected] (1)", processor="x86_64",
system="Linux/4.15.0-1019-aws", leap=00, stratum=11, precision=-24,
rootdelay=0.000, rootdisp=11.016, refid=LOCAL(0),
reftime=de1977a0.2605c5ad  Mon, Jan 29 2018  5:36:16.148,
clock=de1977a6.758ae7fc  Mon, Jan 29 2018  5:36:22.459, peer=57525, tc=6,
mintc=3, offset=0.000000, frequency=0.000, sys_jitter=0.000000,
clk_jitter=0.000, clk_wander=0.000, tai=37, leapsec=201701010000,
expire=201812280000

I tried this script to get time from real NTP server, where it worked, but not on the standalone NTP.

What I am missing here ?

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1 Answer 1

Reset to default
2

One way to see the ports opened by services is:

netstat -an

Of course you can filter the output with grep command like this:

netstat -an|grep 123.

I sometimes use lsof too, like this:

lsof -i udp -nP in RedHat based distros.

See man lsof and man netstat for more info.

I hope this helps.

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  • looks like service is running.
    – rp346
    Jan 17, 2019 at 14:21
  • Nice. Do you have any firewall between server and clients?
    – Manuel Florian
    Jan 17, 2019 at 14:24
  • I checked the firewall status sudo ufw status verbose , which is Status: inactive Also full communication is allowed in AWS-SG from client (10.24.0.0/16) to NTP server
    – rp346
    Jan 17, 2019 at 14:48
  • In the NTP server identify the network interface ntp traffic should be going through and put a tcpdump to see if any traffic is actually reaching the server. e.g tcpdump -i eth0 port 123 -n -nn and from a client nc -u NTPSERVERIP 123.
    – Manuel Florian
    Jan 18, 2019 at 13:24
  • I commented restrict 10.24.0.0 mask 255.255.0.0 notrust and it worked
    – rp346
    Jan 18, 2019 at 21:24

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