Ntp

From LinuxIntro
Revision as of 10:56, 8 June 2015 by 155.56.68.219 (Talk)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

NTP is the network time protocol. It allows you to fetch the current date/time from an internet time server. You can also use it to provide a network time service.

Contents

Synchronize time

To sync the time with the time server pool.ntp.org find out your distribution and use the command

for SUSE

sntp -P no -r ntp.company.com

for other distributions

sntp -s no ntp.company.com

Keep time synchronized

To keep the time synchronized over reboots,

  • sync it one time:
sntp -s no pool.ntp.org 
  • have a file /etc/ntp.conf with one line:
server pool.ntp.org
  • start the NTP service:
/etc/init.d/ntp start
  • configure the NTP service to start on boot, e.g. for SUSE Linux:
chkconfig ntp on

Show time offset from time server

# sntp timeserver.mycompany.com
2014-02-18 10:09:11.391178 (-0100) +6.45592 +/- 0.000427 secs

Means that timeserver.mycompany.com is 6.5 seconds in the future compared to the local clock.

Query status

# /etc/init.d/ntp status
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*timehost1.local .PPS.            1 u  356 1024  377    1.404    0.049   0.154

Checking for network time protocol daemon (NTPD):                    running

Configure it

Edit /etc/ntp.conf, add your time server like this:

server myserver.domain