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ntp_manual_setup(7)
NAME
ntp_manual_setup - Describes how to manually set up the Network Time
Protocol (NTP)
DESCRIPTION
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
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
Use the following procedure to set up your local NTP servers if your time
source is Internet NTP servers:
1. 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.
2. 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.
3. 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
4. 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 (" ").
5. Start the xntpd daemon with the following command:
# /sbin/init.d/xntpd start
6. 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
Use the following procedure to set up your local NTP servers if your time
source is a local reference clock:
1. 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.
2. 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.
3. 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.
4. 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 ("
").
5. Start the xntpd daemon with the following command:
# /sbin/init.d/xntpd start
6. 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
Use the following procedure to set up an NTP client:
1. 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.
2. 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.
3. 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 ("
").
4. Enter the following command to start the xntpd daemon:
# /sbin/init.d/xntpd start
5. 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
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
RELATED INFORMATION
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
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