source: basicnet/netprogs/ntp.xml@ 2174baa

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
   "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;

  <!ENTITY ntp-download-http "http://www.eecis.udel.edu/~ntp/ntp_spool/ntp4/ntp-&ntp-version;.tar.gz">
  <!ENTITY ntp-download-ftp  "ftp://ftp.udel.edu/pub/ntp/ntp4/ntp-&ntp-version;.tar.gz">
  <!ENTITY ntp-md5sum        "0f8fabe87cf54f409b57c6283f0c0c3d">
  <!ENTITY ntp-size          "2.4 MB">
  <!ENTITY ntp-buildsize     "27 MB">
  <!ENTITY ntp-time          "0.53 SBU">
]>

<sect1 id="ntp" xreflabel="NTP-&ntp-version;">
  <?dbhtml filename="ntp.html"?>
  
  <sect1info>
    <othername>$LastChangedBy$</othername>
    <date>$Date$</date>
  </sect1info>
  
  <title>NTP-&ntp-version;</title>
  
  <indexterm zone="ntp">
    <primary sortas="a-NTP">NTP</primary>
  </indexterm>

  <sect2 role="package">
    <title>Introduction to NTP</title>
    
    <para>The <application>NTP</application> 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.</para>
    
    <bridgehead renderas="sect3">Package Information</bridgehead>
    <itemizedlist spacing="compact">
      <listitem>
        <para>Download (HTTP): <ulink url="&ntp-download-http;"/></para>
      </listitem>
      <listitem>
        <para>Download (FTP): <ulink url="&ntp-download-ftp;"/></para>
      </listitem>
      <listitem>
        <para>Download MD5 sum: &ntp-md5sum;</para>
      </listitem>
      <listitem>
        <para>Download size: &ntp-size;</para>
      </listitem>
      <listitem>
        <para>Estimated disk space required: &ntp-buildsize;</para>
      </listitem>
      <listitem>
        <para>Estimated build time: &ntp-time;</para>
      </listitem>
    </itemizedlist>
    
    <bridgehead renderas="sect3">NTP Dependencies</bridgehead>
    
    <bridgehead renderas="sect4">Optional</bridgehead>
    <para><xref linkend="openssl"/></para>
    
  </sect2>
  
  <sect2 role="installation">
    <title>Installation of NTP</title>

    <para>Install <application>NTP</application> by running 
    the following commands:</para>

<screen><userinput>./configure --prefix=/usr --bindir=/usr/sbin \
    --sysconfdir=/etc &amp;&amp;
make &amp;&amp;
make install</userinput></screen>
    
  </sect2>
  
  <sect2 role="configuration">
    <title>Configuring NTP</title>
    
    <sect3 id="ntp-config">
      <title>Config Files</title>
      
      <para><filename>/etc/ntp.conf</filename></para>
      
      <indexterm zone="ntp ntp-config">
        <primary sortas="e-etc-ntp.conf">/etc/ntp.conf</primary>
      </indexterm>
      
    </sect3>
    
    <sect3>
      <title>Configuration Information</title>

      <para>The following configuration file defines various NTP
      stratum 2 servers with open access from different continents. It also
      creates a drift file where <command>ntpd</command> stores the frequency
      offset. Since the documentation included with the package is sparse,
      visit the NTP website at <ulink url="http://www.ntp.org/"/> for more information.</para>

<screen role="root"><userinput>cat &gt; /etc/ntp.conf &lt;&lt; "EOF"
<literal># Africa
server tock.nml.csir.co.za

# Asia
server ntp.shim.org

# Australia
server ntp.saard.net
        
# Europe
server ntp.tuxfamily.net

# North America
server clock.psu.edu

driftfile /var/cache/ntp.drift</literal>
EOF</userinput></screen>

    </sect3>
    
    <sect3  id="ntp-init">
      <title>Synchronizing the Time</title>

      <para>There are two options. Option one is to run <command>ntpd</command>
      continuously and allow it to synchronize the time in a gradual manner. The 
      other option is to run <command>ntpd</command> periodically (using cron)
      and update the time each time <command>ntpd</command> is scheduled.</para>
      
      <para>If you choose Option one, then install the 
      <filename>/etc/rc.d/init.d/ntp</filename>
      init script included in the
      <xref linkend="intro-important-bootscripts"/> package.</para>
      
      <indexterm zone="ntp ntp-init"> 
        <primary sortas="f-ntp">ntp</primary>
      </indexterm> 

<screen role="root"><userinput>make install-ntp</userinput></screen>

      <para>If you prefer to run <command>ntpd</command> periodically, add the 
      following command to <systemitem class="username">root</systemitem>'s 
      <filename>crontab</filename>:</para>
      
<screen><literal>ntpd -q</literal></screen>

      <para>Execute the following command if you would like to set the
      hardware clock at shutdown and reboot based on the current system
      time:</para>

<screen role="root"><userinput>ln -sf ../init.d/setclock /etc/rc.d/rc0.d/K46setclock &amp;&amp;
ln -sf ../init.d/setclock /etc/rc.d/rc6.d/K46setclock</userinput></screen>

      <para>The other way around is already set up by LFS.</para>
      
    </sect3>
    
  </sect2>
  
  <sect2 role="content">
    <title>Contents</title>
    
    <segmentedlist>
      <segtitle>Installed Programs</segtitle>
      <segtitle>Installed Libraries</segtitle>
      <segtitle>Installed Directories</segtitle>
      
      <seglistitem>
        <seg>ntp-keygen, ntp-wait, ntpd, ntpdate, ntpdc, ntpq, 
        ntptime, ntptrace,  and tickadj</seg>
        <seg>None</seg>
        <seg>None</seg>
      </seglistitem>
    </segmentedlist>
    
    <variablelist>
      <bridgehead renderas="sect3">Short Descriptions</bridgehead>
      <?dbfo list-presentation="list"?>
      <?dbhtml list-presentation="table"?>
     
      <varlistentry id="ntp-keygen">
        <term><command>ntp-keygen</command></term>
        <listitem>
          <para>generates cryptographic data files used by the NTPv4 authentication 
          and identification schemes.</para>
          <indexterm zone="ntp ntp-keygen">
            <primary sortas="b-ntp-keygen">ntp-keygen</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      
      <varlistentry id="ntp-wait">
        <term><command>ntp-wait</command></term>
        <listitem>
          <para>is useful at boot time, to delay the boot sequence until 
          <command>ntpd</command> has set the time.</para>
          <indexterm zone="ntp ntp-wait">
            <primary sortas="b-ntp-wait">ntp-wait</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      
      <varlistentry id="ntpd">
        <term><command>ntpd</command></term>
        <listitem>
          <para>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.</para>
          <indexterm zone="ntp ntpd">
            <primary sortas="b-ntpd">ntpd</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      
      <varlistentry id="ntpdate">
        <term><command>ntpdate</command></term>
        <listitem>
          <para>is a client program that sets the date and time based on 
          the response from an NTP server. This command is deprecated.</para>
          <indexterm zone="ntp ntpdate">
            <primary sortas="b-ntpdate">ntpdate</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      
      <varlistentry id="ntpdc">
        <term><command>ntpdc</command></term>
        <listitem>
          <para>is used to query the NTP daemon about its current state 
          and to request changes in that state.</para>
          <indexterm zone="ntp ntpdc">
            <primary sortas="b-ntpdc">ntpdc</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      
      <varlistentry id="ntpq">
        <term><command>ntpq</command></term>
        <listitem>
          <para>is an utility program used to monitor <command>ntpd</command> 
          operations and determine performance.</para>
          <indexterm zone="ntp ntpq">
            <primary sortas="b-ntpq">ntpq</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      
      <varlistentry id="ntptime">
        <term><command>ntptime</command></term>
        <listitem>
          <para>reads and displays time-related kernel variables.</para>
          <indexterm zone="ntp ntptime">
            <primary sortas="b-ntptime">ntptime</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      
      <varlistentry id="ntptrace">
        <term><command>ntptrace</command></term>
        <listitem>
          <para>traces a chain of NTP servers back to the primary source.</para>
          <indexterm zone="ntp ntptrace">
            <primary sortas="b-ntptrace"></primary>
          </indexterm>
        </listitem>
      </varlistentry>
      
      <varlistentry id="tickadj">
        <term><command>tickadj</command></term>
        <listitem>
          <para>reads, and optionally modifies, several timekeeping-related 
          variables in older kernels that do not have support for precision 
          timekeeping.</para>
          <indexterm zone="ntp tickadj">
            <primary sortas="b-tickadj">tickadj</primary>
          </indexterm>
        </listitem>
      </varlistentry>
      
    </variablelist>
    
  </sect2>
  
</sect1>