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ntp_manual_setup(7)
Contents
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ntp_manual_setup - Describes how to manually set up the
Network Time Protocol (NTP)
Setting up the Network Time Protocol (NTP) manually
includes selecting your most accurate time source and then
configuring the following: Local NTP servers NTP clients
You can also choose to set your system time with the rdate
command, which is explained in the SETTING NETWORK TIME
WITH BLANK_SPACE<LITERAL>RDATE</LITERAL> section in this
reference page.
SETTING UP A LOCAL NTP SERVER [Toc] [Back] What you must do to configure a local NTP server depends
on your time source. If your time source is Internet NTP
servers, see the Time Source - Internet NTP Servers section
in this reference page. If your time source is a
local reference clock, see the Time Source - Local Reference
Clock section in this reference page.
Time Source - Internet NTP Servers [Toc] [Back]
Use the following procedure to set up your local NTP
servers if your time source is Internet NTP servers:
Select three Internet primary or secondary servers for
each local NTP server.
Selecting a different set of Internet servers for
each local server is recommended. Secondary
servers are usually as reliable and accurate as
primary servers. See the Network Administration:
Services manual for information on obtaining a list
of Internet servers. Decide which options to the
xntpd daemon you want to run.
You can chose the -g option, the -l option, or
both: The -g option allows the xntpd daemon to correct
time differences of more than 1000 seconds
between your system and that of your system's NTP
servers that occur after the xntpd daemon is
started. Initial time differences are corrected
before the xntpd daemon is started by the ntpdate
command which is run at boot time by the
/sbin/init.d/settime script. If your system is
sensitive to security threats, do not use the -g
option. Normally, NTP logs an initialization message,
error messages, status messages, and several
other informative messages to syslog. The -l option
specifies that NTP will log only the initialization
message and error messages to syslog. Edit the
/etc/ntp.conf file.
You must add a peer entry to the /etc/ntp.conf file
for each Internet server. Each Internet server
must either have an entry in the local /etc/hosts
file or the hosts file distributed by BIND or NIS.
The following /etc/ntp.conf file is for a local NTP
server that is synchronizing its time with the fictitious
Internet time servers host1, host2, and
host3. The version 1 after host3 indicates that
host3 is running the ntpd daemon instead of the
xntpd daemon. (Servers running Tru64 UNIX run the
xntpd daemon.) The line driftfile /etc/ntp.drift
indicates the location of the drift file on this
system.
# # XNTPD Configuration File (template for NTP V3)
# # # Specify a filename for the driftfile created
by xntpd. # /etc/ntp.drift is the default. #
driftfile /etc/ntp.drift # # # # # Specify several
NTP servers and/or peers (See the xntpd # documentation
for recommendations on selecting servers and
peers). # NOTE: Be sure to specify the version
number of the server/peer: # # peer
host1 version 2 # xntpd V2 #
server host2 version 1 # ntpd V1 #
server host3 version 3 # xntpd V3 # # For further
information on configuration options, see the
xntpd # documentation. If you have a local accurate
clock (radio clock, # etcetera), you will need
to specify further configuration options. #
#Server and peer configuration peer host1 version 3
peer host2 version 3 peer host3 version 1 Edit the
/etc/rc.config file by using the /usr/sbin/rcmgr
command. The syntax for the /usr/sbin/rcmgr command
is as follows:
/usr/sbin/rcmgr set variable value
To edit the /etc/rc.config file and add the
required information, enter the following series of
commands:
# /usr/sbin/rcmgr set XNTPD_CONF YES #
/usr/sbin/rcmgr set XNTP_SERV1 host1 #
/usr/sbin/rcmgr set XNTP_SERV2 host2 #
/usr/sbin/rcmgr set XNTP_SERV3 host3 #
/usr/sbin/rcmgr set XNTPD_OPTS "options"
Replace host1, host2, and host3 with the names of
the Internet primary or secondary servers that you
selected in step 1. Replace options with the
options you selected in step 2. You must enclose
the options in quotation marks (" "). Start the
xntpd daemon with the following command:
# /sbin/init.d/xntpd start Verify that NTP is working
by using the ntpq command with the -p option:
# /usr/bin/ntpq -p
For information on monitoring the xntpd daemon and
using the ntpq command, see the ntpq(8) reference
page.
Time Source - Local Reference Clock [Toc] [Back]
Use the following procedure to set up your local NTP
servers if your time source is a local reference clock:
Choose one of your local NTP servers to be the local reference
clock. The other two local NTP servers can be set
up as NTP clients that use the local reference clock and
each other as peers.
For example, if host4, host5, and host6 are the
local NTP servers and host4 is the local reference
clock, then you should set them up as follows: Set
up host5 as an NTP client that specifies host4 and
host6 as its local NTP servers Set up host6 as an
NTP client that specifies host4 and host5 as its
local NTP servers
Complete steps 3 through 6 only if you are setting
up the local reference clock. Decide which options
to the xntpd daemon you want to run.
You can choose the -g option, the -l option, or
both: The -g option allows the xntpd daemon to correct
time differences of more than 1000 seconds
between your system and that of your system's NTP
servers that occur after the xntpd daemon is
started. Initial time differences are corrected
before the xntpd daemon is started by the ntpdate
command which is run at boot time by the
/sbin/init.d/settime script. If your system is sensitive
to security threats, do not use the -g
option. Normally, NTP logs an initialization message,
error messages, status messages, and several
other informative messages to syslog. The -l
option specifies that NTP will log only the initialization
message and error messages to syslog.
Edit the /etc/ntp.conf file and add the following
entry:
# peer 127.127.1.1
This entry allows the local reference clock to run
at stratum 3. For more information about local
reference clocks, see the ntp.conf(4) reference
page. Note that when using a local reference clock,
you should never use stratum 1, since the clock may
provide very inaccurate time. Edit the
/etc/rc.config file by using the /usr/sbin/rcmgr
command. The syntax for the /usr/sbin/rcmgr command
is as follows:
/usr/sbin/rcmgr set variable value
To edit the /etc/rc.config file and add the
required information, enter the following series of
commands:
# /usr/sbin/rcmgr set XNTPD_CONF YES #
/usr/sbin/rcmgr set XNTP_SERV1 host4 #
/usr/sbin/rcmgr set XNTP_SERV2 host5 #
/usr/sbin/rcmgr set XNTP_SERV3 host6 #
/usr/sbin/rcmgr set XNTPD_OPTS "options"
Replace host4, host5, and host6 with the names of
the hosts that you selected to be servers in step
1. Replace options with the options you selected in
step 2. You must enclose the options in quotation
marks (" "). Start the xntpd daemon with the following
command: # /sbin/init.d/xntpd start Verify
that NTP is working by using the ntpq command:
# /usr/bin/ntpq -p
For information on monitoring the xntpd daemon and
using the ntpq command, see the ntpq(8) reference
page.
SETTING UP NTP CLIENTS [Toc] [Back] Use the following procedure to set up an NTP client:
Decide which options to the xntpd daemon you want to run.
You can choose the -g option, the -l option, or
both: The -g option allows the xntpd daemon to correct
time differences of more than 1000 seconds
between your system and that of your system's NTP
servers that occur after the xntpd daemon is
started. Initial time differences are corrected
before the xntpd daemon is started by the ntpdate
command which is run at boot time by the
/sbin/init.d/settime script. If your system is sensitive
to security threats, do not use the -g
option. Normally, NTP logs an initialization message,
error messages, status messages, and several
other informative messages to syslog. The -l
option specifies that NTP will only log the initialization
message and error messages to syslog.
For each client, add a server entry to the
/etc/ntp.conf file for each local NTP server. The
following /etc/ntp.conf file is for an NTP client
that is synchronizing its time with the local NTP
servers host4, host5, and host6. The line driftfile
/etc/ntp.drift indicates the location of the drift
file on this system.
# # XNTPD Configuration File (template for NTP V3)
# # # Specify a filename for the driftfile created
by xntpd. # /etc/ntp.drift is the default. #
driftfile /etc/ntp.drift
.
.
. server host4 version 3 server host5 version 3
server host6 version 3
Remember that each local NTP server that you specify
must have an entry in either the client's
/etc/hosts file or in a BIND or NIS hosts database
that is searched by your system. Edit the
/etc/rc.config file by using the /usr/sbin/rcmgr
command. The syntax for the /usr/sbin/rcmgr command
is as follows:
/usr/sbin/rcmgr set variable value
To edit the /etc/rc.config file and add the
required information, enter the following commands:
# /usr/sbin/rcmgr set XNTPD_CONF YES #
/usr/sbin/rcmgr set XNTP_SERV1 host4 #
/usr/sbin/rcmgr set XNTP_SERV2 host5 #
/usr/sbin/rcmgr set XNTP_SERV3 host6 #
/usr/sbin/rcmgr set XNTPD_OPTS "options"
Replace host4, host5, and host6 with the names of
three local NTP servers for your network. Replace
options with the options you selected in step 1.
You must enclose the options in quotation marks ("
"). Enter the following command to start the xntpd
daemon: # /sbin/init.d/xntpd start Verify that NTP
is working by using the ntpq command with the -p
option:
# /usr/bin/ntpq -p
For information on monitoring the xntpd daemon and
using the ntpq command, see the ntpq(8) reference
page.
SETTING NETWORK TIME WITH RDATE [Toc] [Back] For your system to use the rdate command to set its time
to the average network time when it starts, you must add
an entry for rdate to the /etc/rc.config file.
If your network uses the Network Time Protocol (NTP) time
service you might still want to put the rdate entry in the
/etc/rc.config file; if NTP hosts are unreachable, the
system's time will still be set. If NTP hosts are reachable,
the ntpdate command, which runs after the rdate command,
will set the time to NTP time before starting the
xntpd daemon.
You must use the rcmgr command to edit the /etc/rc.config
file. Enter the following command to add an entry for the
rdate command to the /etc/rc.config file:
# /usr/sbin/rcmgr set RDATE_CONF YES
Commands: ntp(1), timedsetup(8), xntpdc(8)
Daemons: timed(8), xntpd(8)
Routines: ctime(3)
Files: ntp.conf(4)
Introduction: ntp_intro(7)
Network Administration: Services
ntp_manual_setup(7)
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