Syncing Linux clock to a Time server

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Dingbat

Dingbat

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For the pedantic who want the most accurate time possible  :point:

South African stratum2 time servers that you can use in the ntp.conf file

Server DNS name                   
ntp1.meraka.csir.co.za             
ntp2.is.co.za
igubu.saix.net
ntp-ndf.mweb.co.za
ntp0.za.uu.net
ntp1.za.uu.net
ntp.mtnbusiness.co.za


Login as root, in fact all ntp commands will have to done as the root user and use your fav text editor to edit the ntp.conf file located at /etc/ntp.conf I usually prefer to use the vi editor as its is quick and simple but can overwhelm a 'general' user


The file will look something like this, this is taken from Oracle linux but the format should similar regardless of the distro


Code: 
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1
restrict -6 ::1

# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server enter the South african stratum2 servers mentioned above over here
server enter the South african stratum2 servers mentioned above over here
server enter the South african stratum2 servers mentioned above over here

#broadcast 192.168.1.255 key 42         # broadcast server
#broadcastclient                        # broadcast client
#broadcast 224.0.1.1 key 42             # multicast server
#multicastclient 224.0.1.1              # multicast client
#manycastserver 239.255.254.254         # manycast server
#manycastclient 239.255.254.254 key 42  # manycast client

# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available.
server  127.127.1.0     # local clock
fudge   127.127.1.0 stratum 9

# Drift file.  Put this in a directory which the daemon can write to.
# No symbolic links allowed, either, since the daemon updates the file
# by creating a temporary in the same directory and then rename()'ing
# it to the file.
driftfile /var/lib/ntp/drift

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.
#requestkey 8

# Specify the key identifier to use with the ntpq utility.
#controlkey 8

#restrict default ignore

Enter the time servers in the file as indicated in the code above. Save and exit the file

To start the ntp service, as root enter the following

Code: 
chkconfig ntpd on

verify the daemon is running

Code: 
service ntpd status

To verify the results and to see if you are sync'd

Code: 
ntpq -p

should display some thing similar to this

Code: 
    remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 time server.      time server5  u  188 1024  376    0.393  1624.36  32.769
 time server.co. time server5  u  722 1024  377    0.387  -218.51  13.119
*time server.co. time server4  u  350 1024  377    0.301   77.988  13.116
 LOCAL(0)        .LOCL.           9 l   39   64  377    0.000    0.000   0.001

you should be able to see the ip addresses or DNS names of the servers you entered in the conf file.

To verify the 'handshake' enter

Code: 
ntpd -d
 

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