NTP

NTP is a TCP/IP protocol for synchronizing time over a network.

Slackware

Update clock

Run the command as superuser:

   1 ntpdate pool.ntp.org
   2 sudo ntpdate pool.ntp.org

Date and time should be stored in UTC.

Info on slack docs:

http://docs.slackware.com/howtos:network-services:ntp

Enable the service:

   1 chmod 755 /etc/rc.d/rc.ntpd

Start the service manually:

   1 /etc/rc.d/rc.ntpd start
   2 /etc/rc.d/rc.ntpd status

Add ntp server

Edit /etc/ntp.conf
add server pt.pool.ntp.org

   1 server  127.127.1.0     # local clock                                           
   2 fudge   127.127.1.0 stratum 10
   3 server pt.pool.ntp.org
   4 driftfile /etc/ntp/drift
   5 # Don't serve time or stats to anyone else by default (more secure)             
   6 restrict default noquery nomodify
   7 # Trust ourselves.  :-)                                                         
   8 restrict 127.0.0.1

Check the offset in seconds

   1 ntpdate -q pt.pool.ntp.org # offset in seconds
   2 ntpq -pn

CentOS

   1 yum install ntp
   2 service ntpd start
   3 chkconfig ntpd on
   4 service ntpd stop
   5 ntpdate pt.pool.ntp.org # sync clock
   6 service ntpd start
   7 ntpdate -q pt.pool.ntp.org
   8 ntpq -pn

Ubuntu / Debian

   1 apt-get install ntp
   2 ntpdate -q pt.pool.ntp.org
   3 service ntp stop
   4 ntpdate  pt.pool.ntp.org
   5 service ntp start
   6 ntpq -pn
   7 #
   8 apt install -y ntp ntpsec-ntpdate ntpdate
   9 /sbin/ntpdate pt.pool.ntp.org
  10 /sbin/service ntp stop
  11 timedatectl set-timezone Europe/Lisbon
  12 /sbin/service ntp start

FreeBSD 9.0

Run the command:

   1 ntpdate pool.ntp.org

Check the UTC date:

   1 date -u

Edit the file /etc/rc.conf:

   1 ntpd_enabled="YES"

Start and check the NTPD service status:

   1 /etc/rc.d/ntpd start
   2 /etc/rc.d/ntpd status

Sync summer time Slackware

   1 timeconfig # set HW clock to UTC
   2 /etc/rc.d/rc.ntpd stop
   3 ntpdate pt.pool.ntp.org
   4 /etc/rc.d/rc.ntpd start

Windows

net start w32time
w32tm /config /manualpeerlist:pt.pool.ntp.org
w32tm /resync /force