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NTP synchronised problem in our Centos 7.6 node

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# 8  
Old 09-23-2019
Hi Folks,

Just a quick addition to the above, I have currently been installing a couple of RHEL 7.5 servers. They are both running ntp and have been installed from a RHEL 7.5 image and then fully updated from the current Red Hat online repos, so I decided just to tick this one off the build and when I checked the server I find.

Code:
[root@fbakirpomd4 bin]# ntpd --version
ntpd 4.2.6p5

exit 0
[root@fbakirpomd4 bin]# systemctl status ntpd
- ntpd.service - Network Time Service
   Loaded: loaded (/usr/lib/systemd/system/ntpd.service; disabled; vendor preset: disabled)
   Active: active (running) since Tue 2019-09-10 13:46:23 BST; 1 weeks 5 days ago
 Main PID: 32639 (ntpd)
   CGroup: /system.slice/ntpd.service
           └─32639 /usr/sbin/ntpd -u ntp:ntp -g

Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: ntp_io: estimated max descriptors: 1024, initial socket boundary: 16
Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: Listen and drop on 0 v4wildcard 0.0.0.0 UDP 123
Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: Listen and drop on 1 v6wildcard :: UDP 123
Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: Listen normally on 2 lo 127.0.0.1 UDP 123
Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: Listen normally on 3 bond0 10.10.184.51 UDP 123
Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: Listen normally on 4 bond0:0 10.10.184.52 UDP 123
Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: Listening on routing socket on fd #21 for interface updates
Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: 0.0.0.0 c016 06 restart
Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: 0.0.0.0 c012 02 freq_set kernel 0.000 PPM
Sep 10 13:46:23 fbakirpomd4 ntpd[32639]: 0.0.0.0 c011 01 freq_not_set
[root@fbakirpomd4 bin]# ntpstat
unsynchronised
  time server re-starting
   polling server every 8 s
[root@fbakirpomd4 bin]# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 10.107.129.61   .INIT.          16 u    - 1024    0    0.000    0.000   0.000
 10.107.130.62   .INIT.          16 u    - 1024    0    0.000    0.000   0.000
[root@fbakirpomd4 bin]# ntptime
ntp_gettime() returns code 5 (ERROR)
  time e132f4ba.dfb26000  Mon, Sep 23 2019  8:37:30.873, (.873816),
  maximum error 16000000 us, estimated error 16000000 us, TAI offset 0
ntp_adjtime() returns code 5 (ERROR)
  modes 0x0 (),
  offset 0.000 us, frequency 0.000 ppm, interval 1 s,
  maximum error 16000000 us, estimated error 16000000 us,
  status 0x41 (PLL,UNSYNC),
  time constant 7, precision 1.000 us, tolerance 500 ppm,
[root@fbakirpomd4 bin]#

These servers are built from an already supplied Kick Start file, which to be fair is pretty large - much larger than it needs to be to be fair with a huge amount of configuration stuff in the file.

The repo's are setup in the Kick Start as follows;

Code:
[root@fbakirpomd4 bin]# yum repolist
Loaded plugins: product-id, search-disabled-repos, subscription-manager, versionlock
repo id                                            repo name                                                                               status
rhel-7-server-eus-rpms/x86_64                      Red Hat Enterprise Linux 7 Server - Extended Update Support (RPMs)                      21,608
rhel-7-server-rpms/x86_64                          Red Hat Enterprise Linux 7 Server (RPMs)                                                21,088
repolist: 42,696
[root@fbakirpomd4 bin]#

So I'll have a hunt around to try and come up with a reason for the package not updating - a yum update was run against the server.

Regards

Gull04
# 9  
Old 09-23-2019
FWIW, I had the same problem with apt on ubuntu, upgrading to an older and less secure version so I went to the NTP home site and downloaded and installed, in a different directory structure,

Code:
4.2.8p38

The reason was that there has been myriad vulnerabilities and flaws found and fixed in NTP since 2011 when 4.2.6p5 was released.
# 10  
Old 09-23-2019
Hmm,

This might cause me a minor problem, due to the nature of the servers although these are development servers - the production servers keep things running. So it may well be that I'll have to change to Chrony.

I'll investigate my options and report back.

Regards

Gull04
# 11  
Old 09-23-2019
That is actually a good idea for me as well:

chrony - Comparison of NTP implementations

I may switch to chrony .... because I have never really trusted ntp (because of the many ntp code vulnerabilities over the years).
# 12  
Old 09-23-2019
Also, not sure how much confidence we can have in this, but cvedetails reports than 0 Chrony vulnerabilities has been reported after 2016:

Tuxfamily Chrony : CVE security vulnerabilities, versions and detailed reports
# 13  
Old 09-23-2019
Your ntpq output in post#1 is missing a column!?

Are you sure your current ntpd is the only process listening on port 123?
Code:
pgrep '(ntp|chrony)d?$'
netstat -antp | grep -w 123

# 14  
Old 09-24-2019
Hi Folks,

I've been round the houses on this, the decision has been to change from NTP to Chrony. - due mainly to security concerns.

So here's a quick breakdown.

Code:
[root@fbakirpomd4 bin]# systemctl stop ntpd
[root@fbakirpomd4 bin]# chkconfig ntpd off
Note: Forwarding request to 'systemctl disable ntpd.service'.
[root@fbakirpomd4 bin]# systemctl enable chronyd
[root@fbakirpomd4 bin]# systemctl start chronyd
[root@fbakirpomd4 bin]# ps -ef | grep cronyd
root     23225 26147  0 10:11 pts/1    00:00:00 grep --color=auto cronyd
[root@fbakirpomd4 bin]# ps -ef | grep chronyd
chrony   23208     1  0 10:11 ?        00:00:00 /usr/sbin/chronyd
root     23253 26147  0 10:11 pts/1    00:00:00 grep --color=auto chronyd
[root@fbakirpomd4 bin]# cat /etc/chrony.conf
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
# server 0.rhel.pool.ntp.org iburst
# server 1.rhel.pool.ntp.org iburst
# server 2.rhel.pool.ntp.org iburst
# server 3.rhel.pool.ntp.org iburst
##############################################################
#
# Added local hosts for xxxxxxxx xxxxx chrony servers
#
##############################################################
server 10.1.100.134 iburst
server 10.235.100.19 iburst
##############################################################

# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift

# Allow the system clock to be stepped in the first three updates
# if its offset is larger than 1 second.
makestep 1.0 3

# Enable kernel synchronization of the real-time clock (RTC).
rtcsync

# Enable hardware timestamping on all interfaces that support it.
#hwtimestamp *

# Increase the minimum number of selectable sources required to adjust
# the system clock.
#minsources 2

# Allow NTP client access from local network.
#allow 192.168.0.0/16

# Serve time even if not synchronized to a time source.
#local stratum 10

# Specify file containing keys for NTP authentication.
#keyfile /etc/chrony.keys

# Specify directory for log files.
logdir /var/log/chrony

# Select which information is logged.
#log measurements statistics tracking
[root@fbakirpomd4 bin]# systemctl enable chronyd
[root@fbakirpomd4 bin]# systemctl start chronyd
[root@fbakirpomd4 bin]# ps -ef | grep cronyd
root     23225 26147  0 10:11 pts/1    00:00:00 grep --color=auto cronyd
[root@fbakirpomd4 bin]# ps -ef | grep chronyd
chrony   23208     1  0 10:11 ?        00:00:00 /usr/sbin/chronyd
root     23253 26147  0 10:11 pts/1    00:00:00 grep --color=auto chronyd
[root@fbakirpomd4 bin]# chronyc tracking
Reference ID    : 0AEB6413 (ntp2.xxxxxxxxxxxxx.co.uk)
Stratum         : 2
Ref time (UTC)  : Mon Sep 23 09:11:35 2019
System time     : 0.000000041 seconds slow of NTP time
Last offset     : +0.000060960 seconds
RMS offset      : 0.000060960 seconds
Frequency       : 6.443 ppm fast
Residual freq   : -0.865 ppm
Skew            : 0.017 ppm
Root delay      : 0.000187665 seconds
Root dispersion : 0.000315763 seconds
Update interval : 1.8 seconds
Leap status     : Normal
[root@fbakirpomd4 bin]# man chkconfig
[root@fbakirpomd4 bin]# chkconfig chronyd on
Note: Forwarding request to 'systemctl enable chronyd.service'.
[root@fbakirpomd4 bin]#

Checked the servers this morning and all seems well.

Regards

Gull04
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