Beyond Linux From Scratch - Version 6.2.0

Chapter 18. Basic Networking Programs

NTP-4.2.0a

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.

Package Information

NTP Dependencies

Optional

OpenSSL-0.9.8d

User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/ntp

Installation of NTP

Install NTP by running the following commands: 

./configure --prefix=/usr --bindir=/usr/sbin \
    --sysconfdir=/etc &&
make

To test the results, issue: make check.

Now, as the root user: 

make install &&
install -v -m755 -d /usr/share/doc/ntp-4.2.0a &&
cp -v -R html /usr/share/doc/ntp-4.2.0a/

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. 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"
# Africa
server tock.nml.csir.co.za

# 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/cache/ntp.drift
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-20060910 package. 

make install-ntp

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.

Contents

Installed Programs: ntp-keygen, ntp-wait, ntpd, ntpdate, ntpdc, ntpq, ntptime, ntptrace, and tickadj
Installed Libraries: None
Installed Directory: /usr/share/doc/ntp-4.2.0a

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.

tickadj

reads, and optionally modifies, several timekeeping-related variables in older kernels that do not have support for precision timekeeping.

Last updated on 2007-01-30 12:28:32 -0600