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
The update-leap
command needs to be fixed in order to run properly:
sed -e 's/"(\\S+)"/"?([^\\s"]+)"?/' \
-i scripts/update-leap/update-leap.in
Now fix an issue introduced with glibc-2.34:
sed -e 's/#ifndef __sun/#if !defined(__sun) \&\& !defined(__GLIBC__)/' \
-i libntp/work_thread.c
Install ntp by running the
following commands:
./configure --prefix=/usr \
--bindir=/usr/sbin \
--sysconfdir=/etc \
--enable-linuxcaps \
--with-lineeditlibs=readline \
--docdir=/usr/share/doc/ntp-4.2.8p15 &&
make
The test suite of this package is broken with GCC 10 or later.
Now, as the root user:
make install &&
install -v -o ntp -g ntp -d /var/lib/ntp
Command Explanations
CFLAGS="-O2 -g -fPIC": This environment
variable is necessary to generate Position Independent Code needed
for use in the package libraries.
--bindir=/usr/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
switch enables Readline support
for ntpdc and
ntpq programs. If
omitted, libedit will be used if
installed, otherwise no readline capabilities will be compiled.
Configuring ntp
Config Files
/etc/ntp.conf
Configuration Information
The following configuration file first defines various ntp
servers with open access from different continents. Second, it
creates a drift file where ntpd stores the frequency
offset and a pid file to store the ntpd process ID. Third, it
defines the location for the leap-second definition file
/etc/ntp.leapseconds, that the
update-leap script
checks and updates, when necessary. This script can be run as a
cron job and the ntp developers
recommend a frequency of about three weeks for the updates. Since
the documentation included with the package is sparse, visit the
ntp website at https://www.ntp.org/ and https://www.ntppool.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 /run/ntpd.pid
leapfile /var/lib/ntp/ntp.leapseconds
EOF
You may wish to add a “Security session”. For explanations,
see
https://www.eecis.udel.edu/~mills/ntp/html/accopt.html#restrict.
cat >> /etc/ntp.conf << "EOF"
# Security session
restrict default limited kod nomodify notrap nopeer noquery
restrict -6 default limited kod nomodify notrap nopeer noquery
restrict 127.0.0.1
restrict ::1
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.
If you choose Option one, then install the /etc/rc.d/init.d/ntp init
script included in the blfs-bootscripts-20230101 package.
make install-ntpd
If you prefer to run ntpd periodically, add the
following command to root's
crontab:
ntpd -q
Execute the following command if you would like to set the
hardware clock to the current system time at shutdown and reboot:
ln -v -sf ../init.d/setclock /etc/rc.d/rc0.d/K46setclock &&
ln -v -sf ../init.d/setclock /etc/rc.d/rc6.d/K46setclock
The other way around is already set up by LFS.