ntp-4.2.6p5
Introduction to ntp
The ntp package contains a client
and server to keep the time synchronized between various computers
over a network. This package is the official reference
implementation of the NTP protocol.
This package is known to build and work properly using an LFS-7.6
systemd platform.
Package Information
ntp Dependencies
Optional
OpenSSL-1.0.1i and libedit
User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/ntp
Installation of ntp
There should be a dedicated user and group to take control of the
ntpd daemon after it
is started. Issue the following commands as the root
user:
groupadd -g 87 ntp &&
useradd -c "Network Time Protocol" -d /var/lib/ntp -u 87 \
-g ntp -s /bin/false ntp
Install ntp by running the
following commands:
./configure --prefix=/usr \
--sysconfdir=/etc \
--enable-linuxcaps \
--with-binsubdir=sbin \
--with-lineeditlibs=readline &&
make
To test the results, issue: make
check.
Now, as the root
user:
make install &&
install -v -o ntp -g ntp -d /var/lib/ntp &&
install -v -m755 -d /usr/share/doc/ntp-4.2.6p5 &&
cp -v -R html/* /usr/share/doc/ntp-4.2.6p5/
Command Explanations
--with-binsubdir=sbin
: This
parameter places the administrative programs in /usr/sbin
.
--enable-linuxcaps
: ntpd is
run as user ntp, so use Linux capabilities for non-root clock
control.
--with-lineeditlibs=readline
: This
option enables Readline support
for ntpdc and
ntpq programs. If
omitted, libedit will be used if
installed, otherwise no readline capabilites will be compiled.
Configuring ntp
Config Files
/etc/ntp.conf
Configuration Information
The following configuration file defines various ntp servers with
open access from different continents. It also creates a drift
file where ntpd
stores the frequency offset and a pid file to store the
ntpd process ID.
Since the documentation included with the package is sparse,
visit the ntp website at http://www.ntp.org/ and http://www.pool.ntp.org/ for more
information.
cat > /etc/ntp.conf << "EOF"
# Asia
server 0.asia.pool.ntp.org
# Australia
server 0.oceania.pool.ntp.org
# Europe
server 0.europe.pool.ntp.org
# North America
server 0.north-america.pool.ntp.org
# South America
server 2.south-america.pool.ntp.org
driftfile /var/lib/ntp/ntp.drift
pidfile /var/run/ntpd.pid
EOF
Synchronizing the Time
There are two options. Option one is to run ntpd continuously and allow it
to synchronize the time in a gradual manner. The other option is
to run ntpd
periodically (using cron) and update the time each time
ntpd is scheduled.
To start the ntpd
daemon at boot, install the systemd unit from the blfs-systemd-units-20140907 package by
running the following command as the root
user:
make install-ntpd
If you prefer to run ntpd periodically, add the
following command to root
's
crontab
:
ntpd -q
Contents
Installed Programs:
ntp-keygen, ntp-wait, ntpd, ntpdate,
ntpdc, ntpq, ntptime, ntptrace, sntp and tickadj
Installed Libraries:
None
Installed Directory:
/usr/share/doc/ntp-4.2.6p5
Short Descriptions
ntp-keygen
|
generates cryptographic data files used by the NTPv4
authentication and identification schemes.
|
ntp-wait
|
is useful at boot time, to delay the boot sequence until
ntpd has
set the time.
|
ntpd
|
is a ntp daemon that runs in the background and keeps the
date and time synchronized based on response from
configured ntp servers. It also functions as a ntp
server.
|
ntpdate
|
is a client program that sets the date and time based on
the response from an ntp server. This command is
deprecated.
|
ntpdc
|
is used to query the ntp daemon about its current state
and to request changes in that state.
|
ntpq
|
is an utility program used to monitor ntpd operations and
determine performance.
|
ntptime
|
reads and displays time-related kernel variables.
|
ntptrace
|
traces a chain of ntp servers back to the primary source.
|
sntp
|
is a Simple Network Time Protocol (SNTP) client.
|
tickadj
|
reads, and optionally modifies, several
timekeeping-related variables in older kernels that do
not have support for precision timekeeping.
|
Last updated on 2014-08-25 13:50:07 -0700