ntp_manual_setup(7)ntp_manual_setup(7)NAMEntp_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<LIT‐
ERAL>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: 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 reli‐
able and accurate as primary servers. See the Network Adminis‐
tration: 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 sys‐
tem'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) # # # Spec‐
ify 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 informa‐
tion 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 informa‐
tion, 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
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 spec‐
ifies 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 sys‐
tem'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 refer‐
ence 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 informa‐
tion, 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 follow‐
ing command: # /sbin/init.d/xntpd start Verify that NTP is work‐
ing 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: 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 sys‐
tem'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 fol‐
lowing /etc/ntp.conf file is for an NTP client that is synchro‐
nizing 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) # # # Spec‐
ify 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 informa‐
tion, 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 quota‐
tion 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
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 dae‐
mon.
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
ntp_manual_setup(7)