1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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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 |
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8 | <sect1 id="ch-scripts-network">
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9 | <?dbhtml filename="network.html"?>
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10 |
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11 | <title>General Network Configuration</title>
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12 |
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13 | <indexterm zone="ch-scripts-network">
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14 | <primary sortas="d-network">network</primary>
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15 | <secondary>configuring</secondary></indexterm>
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16 |
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17 | <para>This section only applies if a network card is to be
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18 | configured.</para>
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19 |
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20 | <sect2>
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21 | <title>Network Interface Configuration Files</title>
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22 |
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23 | <para>Starting with version 209, systemd ships a network configuration
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24 | daemon called <command>systemd-networkd</command> which can be used for
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25 | basic network configuration. Additionally, since version 213, DNS name
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26 | resolution can be handled by <command>systemd-resolved</command> in place
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27 | of a static <filename>/etc/resolv.conf</filename> file. Both services are
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28 | enabled by defualt, and absolutely should not be disabled.</para>
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29 |
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30 | <para>Configuration files for <command>systemd-networkd</command> (and
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31 | <command>systemd-resolved</command>) can be placed in
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32 | <filename class="directory">/usr/lib/systemd/network</filename>
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33 | or <filename class="directory">/etc/systemd/network</filename>. Files in
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34 | <filename class="directory">/etc/systemd/network</filename> have a
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35 | higher priority than the ones in
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36 | <filename class="directory">/usr/lib/systemd/network</filename>.
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37 | There are three types of configuration files:
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38 | <filename class="extension">.link</filename>,
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39 | <filename class="extension">.netdev</filename> and
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40 | <filename class="extension">.network</filename> files. For detailed
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41 | descriptions and example contents of these configuration files, consult
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42 | the <filename>systemd-link(5)</filename>,
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43 | <filename>systemd-netdev(5)</filename> and
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44 | <filename>systemd-network(5)</filename> manual pages.</para>
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45 |
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46 | <note><para>Udev may assign network card interface names based
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47 | on system physical characteristics such as enp2s1. If you are
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48 | not sure what your interface name is, you can always run
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49 | <command>ip link</command> after you have booted your system.
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50 | </para></note>
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51 |
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52 | <sect3 id="systemd-networkd-static">
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53 | <title>Static IP Configuration</title>
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54 |
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55 | <para>The command below creates a basic configuration file for a
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56 | Static IP setup (using both systemd-networkd and
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57 | systemd-resolved):</para>
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58 |
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59 | <screen role="nodump"><userinput>cat > /etc/systemd/network/10-eth0-static.network << "EOF"
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60 | <literal>[Match]
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61 | Name=eth0
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62 |
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63 | [Network]
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64 | Address=192.168.0.2/24
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65 | Gateway=192.168.0.1
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66 | DNS=192.168.0.1</literal>
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67 | EOF</userinput></screen>
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68 |
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69 | <para>Multiple DNS entries can be added if you have more than one DNS
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70 | server.</para>
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71 |
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72 | </sect3>
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73 |
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74 | <sect3 id="systemd-networkd-dhcp">
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75 | <title>DHCP Configuration</title>
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76 |
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77 | <para>The command below creates a basic configuration file for an IPv4
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78 | DHCP setup:</para>
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79 |
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80 | <screen role="nodump"><userinput>cat > /etc/systemd/network/10-eth0-dhcp.network << "EOF"
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81 | <literal>[Match]
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82 | Name=eth0
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83 |
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84 | [Network]
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85 | DHCP=ipv4</literal>
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86 | EOF</userinput></screen>
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87 |
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88 | </sect3>
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89 |
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90 | </sect2>
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91 |
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92 | <sect2 id="resolv.conf">
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93 | <title>Creating the /etc/resolv.conf File</title>
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94 |
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95 | <indexterm zone="resolv.conf">
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96 | <primary sortas="e-/etc/resolv.conf">/etc/resolv.conf</primary>
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97 | </indexterm>
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98 |
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99 | <para>If the system is going to be connected to the Internet, it will
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100 | need some means of Domain Name Service (DNS) name resolution to
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101 | resolve Internet domain names to IP addresses, and vice versa. This is
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102 | best achieved by placing the IP address of the DNS server, available
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103 | from the ISP or network administrator, into
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104 | <filename>/etc/resolv.conf</filename>.</para>
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105 |
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106 | <sect3 id="resolv-conf-systemd-resoloved">
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107 | <title>systemd-resolved Configuration</title>
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108 |
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109 | <note><para>If using another means to configure your network
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110 | interfaces (ex: ppp, network-manager, etc.), or if using any type of
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111 | local resolver (ex: bind, dnsmasq, etc.), or any other software that
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112 | generates an <filename>/etc/resolv.conf</filename> (ex: resolvconf), the
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113 | <command>systemd-resolved</command> service should not be
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114 | used.</para></note>
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115 |
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116 | <para>When using <command>systemd-resolved</command> for DNS
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117 | configuration, it is responsible for creating the
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118 | <filename>/etc/resolv.conf</filename> file. Since version 226, the
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119 | symlink for <filename>/etc/resolv.conf</filename> is created by systemd
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120 | when needed, so no further configuration is necessary.</para>
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121 |
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122 | </sect3>
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123 |
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124 | <sect3 id="resolv-conf-static">
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125 | <title>Static resolv.conf Configuration</title>
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126 |
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127 | <para>If a static <filename>/etc/resolv.conf</filename> is desired,
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128 | create it by running the following command:</para>
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129 |
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130 | <screen role="nodump"><userinput>cat > /etc/resolv.conf << "EOF"
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131 | <literal># Begin /etc/resolv.conf
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132 |
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133 | domain <replaceable><Your Domain Name></replaceable>
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134 | nameserver <replaceable><IP address of your primary nameserver></replaceable>
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135 | nameserver <replaceable><IP address of your secondary nameserver></replaceable>
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136 |
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137 | # End /etc/resolv.conf</literal>
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138 | EOF</userinput></screen>
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139 |
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140 | <para>The <varname>domain</varname> statement can be omitted
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141 | or replaced with a <varname>search</varname> statement. See the man page
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142 | for resolv.conf for more details.</para>
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143 |
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144 | <para>Replace
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145 | <replaceable><IP address of the nameserver></replaceable>
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146 | with the IP address of the DNS most appropriate for the setup. There will
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147 | often be more than one entry (requirements demand secondary servers for
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148 | fallback capability). If you only need or want one DNS server, remove the
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149 | second <emphasis>nameserver</emphasis> line from the file. The IP address
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150 | may also be a router on the local network.</para>
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151 |
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152 | <note><para>The Google Public IPv4 DNS addresses are
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153 | <parameter>8.8.8.8</parameter> and <parameter>8.8.4.4</parameter>
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154 | for IPv4, and <parameter>2001:4860:4860::8888</parameter> and
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155 | <parameter>2001:4860:4860::8844</parameter> for IPv6.</para></note>
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156 |
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157 | </sect3>
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158 |
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159 | </sect2>
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160 |
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161 | <sect2 id="ch-scripts-hostname">
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162 | <title>Configuring the system hostname</title>
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163 |
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164 | <indexterm zone="ch-scripts-hostname">
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165 | <primary sortas="d-hostname">hostname</primary>
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166 | <secondary>configuring</secondary>
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167 | </indexterm>
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168 |
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169 | <para>During the boot process, the file <filename>/etc/hostname</filename>
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170 | is used for establishing the system's hostname.</para>
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171 |
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172 | <para>Create the <filename>/etc/hostname</filename> file and enter a
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173 | hostname by running:</para>
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174 |
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175 | <screen><userinput>echo "<replaceable><lfs></replaceable>" > /etc/hostname</userinput></screen>
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176 |
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177 | <para><replaceable><lfs></replaceable> needs to be replaced with the
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178 | name given to the computer. Do not enter the Fully Qualified Domain Name
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179 | (FQDN) here. That information is put in the
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180 | <filename>/etc/hosts</filename> file.</para>
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181 |
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182 | </sect2>
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183 |
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184 | <sect2 id="ch-scripts-hosts">
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185 | <title>Customizing the /etc/hosts File</title>
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186 |
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187 | <indexterm zone="ch-scripts-hosts">
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188 | <primary sortas="e-/etc/hosts">/etc/hosts</primary>
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189 | </indexterm>
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190 |
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191 | <indexterm zone="ch-scripts-hosts">
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192 | <primary sortas="d-localnet">localnet</primary>
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193 | <secondary>/etc/hosts</secondary>
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194 | </indexterm>
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195 |
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196 | <indexterm zone="ch-scripts-hosts">
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197 | <primary sortas="d-network">network</primary>
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198 | <secondary>/etc/hosts</secondary>
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199 | </indexterm>
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200 |
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201 | <para>Decide on a fully-qualified domain name (FQDN), and possible aliases
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202 | for use in the <filename>/etc/hosts</filename> file. If using static
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203 | addresses, you'll also need to decide on an IP address. The syntax
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204 | for a hosts file entry is:</para>
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205 |
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206 | <screen><literal>IP_address myhost.example.org aliases</literal></screen>
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207 |
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208 | <para>Unless the computer is to be visible to the Internet (i.e., there is
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209 | a registered domain and a valid block of assigned IP addresses—most
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210 | users do not have this), make sure that the IP address is in the private
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211 | network IP address range. Valid ranges are:</para>
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212 |
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213 | <screen><literal>Private Network Address Range Normal Prefix
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214 | 10.0.0.1 - 10.255.255.254 8
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215 | 172.x.0.1 - 172.x.255.254 16
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216 | 192.168.y.1 - 192.168.y.254 24</literal></screen>
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217 |
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218 | <para>x can be any number in the range 16-31. y can be any number in the
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219 | range 0-255.</para>
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220 |
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221 | <para>A valid private IP address could be 192.168.1.1. A valid FQDN for
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222 | this IP could be lfs.example.org.</para>
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223 |
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224 | <para>Even if not using a network card, a valid FQDN is still required.
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225 | This is necessary for certain programs to operate correctly.</para>
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226 |
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227 | <para>If using DHCP, DHCPv6, IPv6 Autoconfiguration, or if a network card
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228 | is not going to be configured, create the <filename>/etc/hosts</filename>
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229 | file by running the following command:</para>
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230 |
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231 | <screen><userinput>cat > /etc/hosts << "EOF"
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232 | <literal># Begin /etc/hosts
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233 |
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234 | 127.0.0.1 <replaceable><HOSTNAME.example.org></replaceable> <replaceable><HOSTNAME></replaceable> localhost <replaceable>[alias1] [alias2] ...</replaceable>
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235 | ::1 <replaceable><HOSTNAME.example.org></replaceable> <replaceable><HOSTNAME></replaceable> localhost <replaceable>[alias1] [alias2] ...</replaceable>
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236 |
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237 | # End /etc/hosts</literal>
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238 | EOF</userinput></screen>
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239 |
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240 | <para>The ::1 entry is the IPv6 counterpart of 127.0.0.1 and represents
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241 | the IPv6 loopback interface.</para>
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242 |
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243 | <para>If ussing a staic address, create the <filename>/etc/hosts</filename>
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244 | file by running this command instead:</para>
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245 |
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246 | <screen role="nodump"><userinput>cat > /etc/hosts << "EOF"
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247 | <literal># Begin /etc/hosts
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248 |
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249 | 127.0.0.1 localhost
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250 | ::1 localhost
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251 | <replaceable><192.168.0.2></replaceable> <replaceable><HOSTNAME.example.org></replaceable> <replaceable><HOSTNAME></replaceable> <replaceable>[alias1] [alias2] ...</replaceable>
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252 |
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253 | # End /etc/hosts</literal>
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254 | EOF</userinput></screen>
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255 |
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256 | <para>The <replaceable><192.168.0.2></replaceable>,
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257 | <replaceable><HOSTNAME.example.org></replaceable>, and
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258 | <replaceable><HOSTNAME></replaceable> values need to be
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259 | changed for specific uses or requirements (if assigned an IP address by a
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260 | network/system administrator and the machine will be connected to an
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261 | existing network). The optional alias name(s) can be omitted.</para>
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262 |
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263 | </sect2>
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264 |
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265 | </sect1>
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