1 | <?xml version="1.0" encoding="UTF-8"?>
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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4 | <!ENTITY % general-entities SYSTEM "../../general.ent">
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5 | %general-entities;
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6 |
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7 | <!ENTITY ntp-download-http "https://www.eecis.udel.edu/~ntp/ntp_spool/ntp4/ntp-4.2/ntp-&ntp-version;.tar.gz">
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8 | <!ENTITY ntp-download-ftp " ">
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9 | <!ENTITY ntp-md5sum "516bdabd94ab7c824e9771390761a46c">
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10 | <!ENTITY ntp-size "6.8 MB">
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11 | <!ENTITY ntp-buildsize "99 MB (with tests)">
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12 | <!ENTITY ntp-time "0.8 SBU (With tests; both using parallelism=4)">
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13 | ]>
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14 |
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15 | <sect1 id="ntp" xreflabel="ntp-&ntp-version;">
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16 | <?dbhtml filename="ntp.html"?>
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17 |
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18 |
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19 | <title>ntp-&ntp-version;</title>
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20 |
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21 | <indexterm zone="ntp">
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22 | <primary sortas="a-ntp">ntp</primary>
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23 | </indexterm>
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24 |
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25 | <sect2 role="package">
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26 | <title>Introduction to ntp</title>
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27 |
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28 | <para>
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29 | The <application>ntp</application> package contains a client and server
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30 | to keep the time synchronized between various computers over
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31 | a network. This package is the official reference implementation of the
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32 | NTP protocol.
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33 | </para>
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34 |
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35 | &lfs122_checked;
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36 |
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37 | <bridgehead renderas="sect3">Package Information</bridgehead>
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38 | <itemizedlist spacing="compact">
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39 | <listitem>
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40 | <para>
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41 | Download (HTTP): <ulink url="&ntp-download-http;"/>
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42 | </para>
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43 | </listitem>
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44 | <listitem>
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45 | <para>
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46 | Download (FTP): <ulink url="&ntp-download-ftp;"/>
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47 | </para>
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48 | </listitem>
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49 | <listitem>
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50 | <para>
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51 | Download MD5 sum: &ntp-md5sum;
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52 | </para>
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53 | </listitem>
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54 | <listitem>
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55 | <para>
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56 | Download size: &ntp-size;
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57 | </para>
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58 | </listitem>
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59 | <listitem>
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60 | <para>
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61 | Estimated disk space required: &ntp-buildsize;
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62 | </para>
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63 | </listitem>
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64 | <listitem>
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65 | <para>
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66 | Estimated build time: &ntp-time;
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67 | </para>
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68 | </listitem>
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69 | </itemizedlist>
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70 |
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71 | <bridgehead renderas="sect3">ntp Dependencies</bridgehead>
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72 |
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73 | <bridgehead renderas="sect4">Required</bridgehead>
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74 | <para role="required">
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75 | <xref linkend="perl-io-socket-ssl"/>
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76 | </para>
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77 |
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78 | <!-- Tested 4.2.8p11 with neither wget nor lynx on system: Not required.
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79 | <bridgehead renderas="sect4">Recommended</bridgehead>
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80 | <para role="recommended">
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81 | <xref role="runtime" linkend="wget"/> (runtime, for
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82 | <command>update-leap</command>)
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83 | <!- - The download code for update-leap uses the File::Fetch perl module,
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84 | which may use wget, or lynx, or some core perl modules, so maybe move
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85 | to optional - ->
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86 | </para>
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87 | -->
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88 | <bridgehead renderas="sect4">Optional</bridgehead>
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89 | <para role="optional">
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90 | <xref linkend="libcap-pam"/>,
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91 | <xref linkend="libevent"/>,
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92 | <ulink url="https://www.thrysoee.dk/editline/">libedit</ulink>, and
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93 | <ulink url="https://www.gnu.org/software/autogen/">libopts from AutoGen</ulink>
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94 | </para>
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95 |
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96 | <para condition="html" role="usernotes">Editor Notes:
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97 | <ulink url="&blfs-wiki;/ntp"/></para>
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98 |
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99 | </sect2>
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100 |
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101 | <sect2 role="installation">
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102 | <title>Installation of ntp</title>
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103 |
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104 | <para>
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105 | There should be a dedicated user and group to take control
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106 | of the <command>ntpd</command> daemon after it is
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107 | started. Issue the following commands as the
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108 | <systemitem class="username">root</systemitem> user:
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109 | </para>
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110 |
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111 | <screen role="root"><userinput>groupadd -g 87 ntp &&
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112 | useradd -c "Network Time Protocol" -d /var/lib/ntp -u 87 \
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113 | -g ntp -s /bin/false ntp</userinput></screen>
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114 |
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115 | <!-- At least one of the issues has been reported upstream. The next para
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116 | is valid for 4.8.2p10.
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117 |
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118 | Leap secongs have been deprecated as of November 2022.
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119 | https://en.wikipedia.org/wiki/Leap_second
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120 |
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121 | <para>
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122 | The <command>update-leap</command> command needs to be fixed in order
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123 | to run properly:
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124 | </para>
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125 |
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126 | <screen><userinput>sed -e 's/"(\\S+)"/"?([^\\s"]+)"?/' \
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127 | -i scripts/update-leap/update-leap.in</userinput></screen>
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128 | -->
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129 |
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130 | <para>
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131 | Fix an type issue by executing
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132 | </para>
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133 |
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134 | <screen><userinput>sed -e "s;pthread_detach(NULL);pthread_detach(0);" \
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135 | -i configure \
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136 | sntp/configure</userinput></screen>
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137 |
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138 | <para>
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139 | Install <application>ntp</application> by running
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140 | the following commands:
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141 | </para>
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142 |
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143 | <screen><userinput>./configure --prefix=/usr \
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144 | --bindir=/usr/sbin \
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145 | --sysconfdir=/etc \
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146 | --enable-linuxcaps \
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147 | --with-lineeditlibs=readline \
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148 | --docdir=/usr/share/doc/ntp-&ntp-version; &&
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149 | make</userinput></screen>
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150 |
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151 | <para>
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152 | To test the results, issue: <command>make check</command>.
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153 | </para>
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154 |
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155 | <para>
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156 | Now, as the <systemitem class="username">root</systemitem> user:
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157 | </para>
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158 |
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159 | <screen role="root"><userinput>make install &&
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160 | install -v -o ntp -g ntp -d /var/lib/ntp</userinput></screen>
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161 |
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162 | </sect2>
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163 |
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164 | <sect2 role="commands">
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165 | <title>Command Explanations</title>
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166 |
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167 | <para>
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168 | <parameter>--bindir=/usr/sbin</parameter>: This parameter places
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169 | the administrative programs in <filename
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170 | class="directory">/usr/sbin</filename>.
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171 | </para>
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172 |
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173 | <para>
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174 | <parameter>--enable-linuxcaps</parameter>: ntpd is run as user
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175 | ntp, so use Linux capabilities for non-root clock control.
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176 | </para>
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177 |
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178 | <para>
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179 | <parameter>--with-lineeditlibs=readline</parameter>: This switch
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180 | enables <application>Readline</application> support for
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181 | <command>ntpdc</command> and <command>ntpq</command> programs. If omitted,
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182 | <application>libedit</application> will be used if installed, otherwise no
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183 | readline capabilities will be compiled.
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184 | </para>
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185 |
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186 | </sect2>
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187 |
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188 | <sect2 role="configuration">
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189 | <title>Configuring ntp</title>
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190 |
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191 | <sect3 id="ntp-config">
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192 | <title>Config Files</title>
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193 |
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194 | <para>
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195 | <filename>/etc/ntp.conf</filename>
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196 | </para>
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197 |
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198 | <indexterm zone="ntp ntp-config">
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199 | <primary sortas="e-etc-ntp.conf">/etc/ntp.conf</primary>
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200 | </indexterm>
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201 |
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202 | </sect3>
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203 |
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204 | <sect3>
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205 | <title>Configuration Information</title>
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206 |
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207 | <para>
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208 | The following configuration file first defines various ntp
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209 | servers with open access from different continents. Second, it
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210 | creates a drift file where <command>ntpd</command> stores the
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211 | frequency offset and a pid file to store the
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212 | <command>ntpd</command> process ID. <!--Third, it defines the location
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213 | for the leap-second definition file
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214 | <filename>/etc/ntp.leapseconds</filename>, that the
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215 | <command>update-leap</command> script checks and updates, when
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216 | necessary. This script can be run as a cron job and the
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217 | <application>ntp</application> developers recommend a frequency of
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218 | about three weeks for the updates.--> Since the documentation included
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219 | with the package is sparse, visit the ntp website at
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220 | <ulink url="https://www.ntp.org/"/> and
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221 | <ulink url="https://www.ntppool.org/"/> for more information.
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222 | </para>
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223 |
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224 | <screen role="root"><userinput>cat > /etc/ntp.conf << "EOF"
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225 | <literal># Asia
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226 | server 0.asia.pool.ntp.org
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227 |
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228 | # Australia
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229 | server 0.oceania.pool.ntp.org
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230 |
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231 | # Europe
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232 | server 0.europe.pool.ntp.org
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233 |
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234 | # North America
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235 | server 0.north-america.pool.ntp.org
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236 |
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237 | # South America
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238 | server 2.south-america.pool.ntp.org
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239 |
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240 | driftfile /var/lib/ntp/ntp.drift
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241 | pidfile /run/ntpd.pid</literal>
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242 | EOF</userinput></screen>
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243 |
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244 | <para>
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245 | You may wish to add a <quote>Security session.</quote> For
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246 | explanations, see <ulink url=
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247 | "https://www.eecis.udel.edu/~mills/ntp/html/accopt.html#restrict"/>.
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248 | </para>
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249 |
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250 | <screen role="root"><userinput>cat >> /etc/ntp.conf << "EOF"
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251 | <literal># Security session
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252 | restrict default limited kod nomodify notrap nopeer noquery
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253 | restrict -6 default limited kod nomodify notrap nopeer noquery
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254 |
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255 | restrict 127.0.0.1
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256 | restrict ::1</literal>
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257 | EOF</userinput></screen>
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258 |
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259 | </sect3>
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260 |
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261 | <sect3 id="ntp-init">
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262 | <title>Synchronizing the Time</title>
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263 |
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264 | <para>
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265 | There are two options. Option one is to run <command>ntpd</command>
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266 | continuously and allow it to synchronize the time in a gradual manner.
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267 | The other option is to run <command>ntpd</command> periodically (using
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268 | cron) and update the time each time <command>ntpd</command> is
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269 | scheduled.
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270 | </para>
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271 |
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272 | <para>
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273 | If you choose Option one, then install the
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274 | <phrase revision="sysv"><filename>/etc/rc.d/init.d/ntp</filename>
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275 | init script</phrase>
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276 | <phrase revision="systemd"><filename>ntpd.service</filename>
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277 | unit</phrase>
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278 | included in the
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279 | <xref linkend="bootscripts" revision="sysv"/>
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280 | <xref linkend="systemd-units" revision="systemd"/> package.
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281 | </para>
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282 |
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283 | <indexterm zone="ntp ntp-init" revision="sysv">
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284 | <primary sortas="f-ntp">ntp</primary>
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285 | </indexterm>
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286 |
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287 | <indexterm zone="ntp ntp-init" revision="systemd">
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288 | <primary sortas="f-ntpd">ntpd.service</primary>
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289 | </indexterm>
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290 |
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291 | <screen role="root"><userinput>make install-ntpd</userinput></screen>
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292 |
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293 | <para>
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294 | If you prefer to run <command>ntpd</command> periodically, add the
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295 | following command to <systemitem class="username">root</systemitem>'s
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296 | <filename>crontab</filename>:
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297 | </para>
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298 |
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299 | <screen><literal>ntpd -q</literal></screen>
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300 |
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301 | <para revision="sysv">
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302 | Execute the following command if you would like to set the hardware
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303 | clock to the current system time at shutdown and reboot:
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304 | </para>
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305 |
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306 | <screen role="root" revision="sysv"><userinput>ln -v -sf ../init.d/setclock /etc/rc.d/rc0.d/K46setclock &&
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307 | ln -v -sf ../init.d/setclock /etc/rc.d/rc6.d/K46setclock</userinput></screen>
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308 |
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309 | <para revision="sysv">
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310 | The other way around is already set up by LFS.
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311 | </para>
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312 |
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313 | </sect3>
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314 |
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315 | </sect2>
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316 |
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317 | <sect2 role="content">
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318 | <title>Contents</title>
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319 |
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320 | <segmentedlist>
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321 | <segtitle>Installed Programs</segtitle>
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322 | <segtitle>Installed Libraries</segtitle>
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323 | <segtitle>Installed Directories</segtitle>
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324 |
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325 | <seglistitem>
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326 | <seg>calc_tickadj, ntp-keygen, ntp-wait, ntpd, ntpdate, ntpdc, ntpq,
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327 | ntptime, ntptrace, sntp, tickadj, and update-leap</seg>
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328 | <seg>None</seg>
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329 | <seg>/usr/share/ntp,
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330 | /usr/share/doc/ntp-4.2.8 and
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331 | /var/lib/ntp</seg>
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332 | </seglistitem>
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333 | </segmentedlist>
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334 |
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335 | <variablelist>
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336 | <bridgehead renderas="sect3">Short Descriptions</bridgehead>
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337 | <?dbfo list-presentation="list"?>
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338 | <?dbhtml list-presentation="table"?>
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339 |
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340 | <varlistentry id="calc_tickadj">
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341 | <term><command>calc_tickadj</command></term>
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342 | <listitem>
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343 | <para>
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344 | calculates optimal value for tick given ntp drift file
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345 | </para>
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346 | <indexterm zone="ntp calc_tickadj">
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347 | <primary sortas="b-calc_tickadj">calc_tickadj</primary>
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348 | </indexterm>
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349 | </listitem>
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350 | </varlistentry>
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351 |
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352 | <varlistentry id="ntp-keygen">
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353 | <term><command>ntp-keygen</command></term>
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354 | <listitem>
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355 | <para>
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356 | generates cryptographic data files used by the NTPv4 authentication
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357 | and identification schemes
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358 | </para>
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359 | <indexterm zone="ntp ntp-keygen">
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360 | <primary sortas="b-ntp-keygen">ntp-keygen</primary>
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361 | </indexterm>
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362 | </listitem>
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363 | </varlistentry>
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364 |
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365 | <varlistentry id="ntp-wait">
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366 | <term><command>ntp-wait</command></term>
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367 | <listitem>
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368 | <para>
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369 | is useful at boot time, to delay the boot sequence until
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370 | <command>ntpd</command> has set the time
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371 | </para>
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372 | <indexterm zone="ntp ntp-wait">
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373 | <primary sortas="b-ntp-wait">ntp-wait</primary>
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374 | </indexterm>
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375 | </listitem>
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376 | </varlistentry>
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377 |
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378 | <varlistentry id="ntpd">
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379 | <term><command>ntpd</command></term>
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380 | <listitem>
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381 | <para>
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382 | is a ntp daemon that runs in the background and keeps
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383 | the date and time synchronized based on response from configured
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384 | ntp servers. It also functions as a ntp server
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385 | </para>
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386 | <indexterm zone="ntp ntpd">
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387 | <primary sortas="b-ntpd">ntpd</primary>
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388 | </indexterm>
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389 | </listitem>
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390 | </varlistentry>
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391 |
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392 | <varlistentry id="ntpdate">
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393 | <term><command>ntpdate</command></term>
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394 | <listitem>
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395 | <para>
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396 | is a client program that sets the date and time based on
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397 | the response from an ntp server. This command is deprecated
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398 | </para>
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399 | <indexterm zone="ntp ntpdate">
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400 | <primary sortas="b-ntpdate">ntpdate</primary>
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401 | </indexterm>
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402 | </listitem>
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403 | </varlistentry>
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404 |
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405 | <varlistentry id="ntpdc">
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406 | <term><command>ntpdc</command></term>
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407 | <listitem>
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408 | <para>
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409 | is used to query the ntp daemon about its current state
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410 | and to request changes in that state
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411 | </para>
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412 | <indexterm zone="ntp ntpdc">
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413 | <primary sortas="b-ntpdc">ntpdc</primary>
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414 | </indexterm>
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415 | </listitem>
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416 | </varlistentry>
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417 |
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418 | <varlistentry id="ntpq">
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419 | <term><command>ntpq</command></term>
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420 | <listitem>
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421 | <para>
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422 | is a utility program used to monitor <command>ntpd</command>
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423 | operations and determine performance
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424 | </para>
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425 | <indexterm zone="ntp ntpq">
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426 | <primary sortas="b-ntpq">ntpq</primary>
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427 | </indexterm>
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428 | </listitem>
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429 | </varlistentry>
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430 |
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431 | <varlistentry id="ntptime">
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432 | <term><command>ntptime</command></term>
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433 | <listitem>
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434 | <para>
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435 | reads and displays time-related kernel variables
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436 | </para>
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437 | <indexterm zone="ntp ntptime">
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438 | <primary sortas="b-ntptime">ntptime</primary>
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439 | </indexterm>
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440 | </listitem>
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441 | </varlistentry>
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442 |
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443 | <varlistentry id="ntptrace">
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444 | <term><command>ntptrace</command></term>
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445 | <listitem>
|
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446 | <para>
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447 | traces a chain of ntp servers back to the primary source
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448 | </para>
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449 | <indexterm zone="ntp ntptrace">
|
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450 | <primary sortas="b-ntptrace">ntptrace</primary>
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451 | </indexterm>
|
---|
452 | </listitem>
|
---|
453 | </varlistentry>
|
---|
454 |
|
---|
455 | <varlistentry id="sntp">
|
---|
456 | <term><command>sntp</command></term>
|
---|
457 | <listitem>
|
---|
458 | <para>
|
---|
459 | is a Simple Network Time Protocol (SNTP) client
|
---|
460 | </para>
|
---|
461 | <indexterm zone="ntp sntp">
|
---|
462 | <primary sortas="b-sntp">sntp</primary>
|
---|
463 | </indexterm>
|
---|
464 | </listitem>
|
---|
465 | </varlistentry>
|
---|
466 |
|
---|
467 | <varlistentry id="tickadj">
|
---|
468 | <term><command>tickadj</command></term>
|
---|
469 | <listitem>
|
---|
470 | <para>
|
---|
471 | reads, and optionally modifies, several timekeeping-related
|
---|
472 | variables in older kernels that do not have support for precision
|
---|
473 | timekeeping
|
---|
474 | </para>
|
---|
475 | <indexterm zone="ntp tickadj">
|
---|
476 | <primary sortas="b-tickadj">tickadj</primary>
|
---|
477 | </indexterm>
|
---|
478 | </listitem>
|
---|
479 | </varlistentry>
|
---|
480 |
|
---|
481 | <varlistentry id="update-leap">
|
---|
482 | <term><command>update-leap</command></term>
|
---|
483 | <listitem>
|
---|
484 | <para>
|
---|
485 | is a script to verify and, if necessary, update the leap-second
|
---|
486 | definition file.
|
---|
487 |
|
---|
488 | <note>
|
---|
489 | <para>
|
---|
490 | In November 2022, at the 27th General Conference on Weights and
|
---|
491 | Measures, it was decided to abandon the leap second. In addition
|
---|
492 | this script hardcodes a URL for an update file that no longer
|
---|
493 | exists. The last time a leap second was declared was January 2017.
|
---|
494 | This script will probably be removed in a future release.
|
---|
495 | </para>
|
---|
496 | </note>
|
---|
497 | </para>
|
---|
498 | <indexterm zone="ntp update-leap">
|
---|
499 | <primary sortas="b-update-leap">update-leap</primary>
|
---|
500 | </indexterm>
|
---|
501 | </listitem>
|
---|
502 | </varlistentry>
|
---|
503 |
|
---|
504 | </variablelist>
|
---|
505 |
|
---|
506 | </sect2>
|
---|
507 |
|
---|
508 | </sect1>
|
---|