[1118b17] | 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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[35a5259] | 8 | <sect1 id="ch-scripts-network" revision="systemd">
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[1118b17] | 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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[c8389f0] | 28 | enabled by default, and absolutely should not be disabled.</para>
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[1118b17] | 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
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| 67 | Domains=<replaceable><Your Domain Name></replaceable></literal>
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| 68 | EOF</userinput></screen>
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| 69 |
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| 70 | <para>Multiple DNS entries can be added if you have more than one DNS
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| 71 | server. Do not include DNS or Domains entries if you intend to use a
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[7eac1a5e] | 72 | static <filename>/etc/resolv.conf</filename> file.</para>
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[1118b17] | 73 |
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| 74 | </sect3>
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| 75 |
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| 76 | <sect3 id="systemd-networkd-dhcp">
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| 77 | <title>DHCP Configuration</title>
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| 78 |
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| 79 | <para>The command below creates a basic configuration file for an IPv4
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| 80 | DHCP setup:</para>
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| 81 |
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| 82 | <screen role="nodump"><userinput>cat > /etc/systemd/network/10-eth0-dhcp.network << "EOF"
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| 83 | <literal>[Match]
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| 84 | Name=eth0
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| 85 |
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| 86 | [Network]
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| 87 | DHCP=ipv4
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| 88 |
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| 89 | [DHCP]
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| 90 | UseDomains=true</literal>
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| 91 | EOF</userinput></screen>
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| 92 |
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| 93 | </sect3>
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| 94 |
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| 95 | </sect2>
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| 96 |
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| 97 | <sect2 id="resolv.conf">
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| 98 | <title>Creating the /etc/resolv.conf File</title>
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| 99 |
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| 100 | <indexterm zone="resolv.conf">
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| 101 | <primary sortas="e-/etc/resolv.conf">/etc/resolv.conf</primary>
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| 102 | </indexterm>
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| 103 |
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| 104 | <para>If the system is going to be connected to the Internet, it will
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| 105 | need some means of Domain Name Service (DNS) name resolution to
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| 106 | resolve Internet domain names to IP addresses, and vice versa. This is
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| 107 | best achieved by placing the IP address of the DNS server, available
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| 108 | from the ISP or network administrator, into
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| 109 | <filename>/etc/resolv.conf</filename>.</para>
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| 110 |
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| 111 | <sect3 id="resolv-conf-systemd-resoloved">
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| 112 | <title>systemd-resolved Configuration</title>
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| 113 |
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| 114 | <note><para>If using another means to configure your network
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| 115 | interfaces (ex: ppp, network-manager, etc.), or if using any type of
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| 116 | local resolver (ex: bind, dnsmasq, etc.), or any other software that
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| 117 | generates an <filename>/etc/resolv.conf</filename> (ex: resolvconf), the
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| 118 | <command>systemd-resolved</command> service should not be
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| 119 | used.</para></note>
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| 120 |
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| 121 | <para>When using <command>systemd-resolved</command> for DNS
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| 122 | configuration, it is responsible for creating the
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| 123 | <filename>/etc/resolv.conf</filename> file. Since version 226, the
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| 124 | symlink for <filename>/etc/resolv.conf</filename> is created by systemd
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| 125 | when needed, so no further configuration is necessary.</para>
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| 126 |
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| 127 | </sect3>
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| 128 |
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| 129 | <sect3 id="resolv-conf-static">
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| 130 | <title>Static resolv.conf Configuration</title>
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| 131 |
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| 132 | <para>If a static <filename>/etc/resolv.conf</filename> is desired,
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| 133 | create it by running the following command:</para>
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| 134 |
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| 135 | <screen role="nodump"><userinput>cat > /etc/resolv.conf << "EOF"
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| 136 | <literal># Begin /etc/resolv.conf
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| 137 |
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| 138 | domain <replaceable><Your Domain Name></replaceable>
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| 139 | nameserver <replaceable><IP address of your primary nameserver></replaceable>
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| 140 | nameserver <replaceable><IP address of your secondary nameserver></replaceable>
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| 141 |
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| 142 | # End /etc/resolv.conf</literal>
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| 143 | EOF</userinput></screen>
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| 144 |
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| 145 | <para>The <varname>domain</varname> statement can be omitted
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| 146 | or replaced with a <varname>search</varname> statement. See the man page
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| 147 | for resolv.conf for more details.</para>
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| 148 |
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| 149 | <para>Replace
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| 150 | <replaceable><IP address of the nameserver></replaceable>
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| 151 | with the IP address of the DNS most appropriate for the setup. There will
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| 152 | often be more than one entry (requirements demand secondary servers for
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| 153 | fallback capability). If you only need or want one DNS server, remove the
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| 154 | second <emphasis>nameserver</emphasis> line from the file. The IP address
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| 155 | may also be a router on the local network.</para>
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| 156 |
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| 157 | <note><para>The Google Public IPv4 DNS addresses are
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| 158 | <parameter>8.8.8.8</parameter> and <parameter>8.8.4.4</parameter>
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| 159 | for IPv4, and <parameter>2001:4860:4860::8888</parameter> and
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| 160 | <parameter>2001:4860:4860::8844</parameter> for IPv6.</para></note>
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| 161 |
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| 162 | </sect3>
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| 163 |
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| 164 | </sect2>
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| 165 |
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| 166 | <sect2 id="ch-scripts-hostname">
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| 167 | <title>Configuring the system hostname</title>
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| 168 |
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| 169 | <indexterm zone="ch-scripts-hostname">
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| 170 | <primary sortas="d-hostname">hostname</primary>
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| 171 | <secondary>configuring</secondary>
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| 172 | </indexterm>
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| 173 |
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| 174 | <para>During the boot process, the file <filename>/etc/hostname</filename>
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| 175 | is used for establishing the system's hostname.</para>
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| 176 |
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| 177 | <para>Create the <filename>/etc/hostname</filename> file and enter a
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| 178 | hostname by running:</para>
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| 179 |
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| 180 | <screen><userinput>echo "<replaceable><lfs></replaceable>" > /etc/hostname</userinput></screen>
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| 181 |
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| 182 | <para><replaceable><lfs></replaceable> needs to be replaced with the
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| 183 | name given to the computer. Do not enter the Fully Qualified Domain Name
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| 184 | (FQDN) here. That information is put in the
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| 185 | <filename>/etc/hosts</filename> file.</para>
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| 186 |
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| 187 | </sect2>
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| 188 |
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| 189 | <sect2 id="ch-scripts-hosts">
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| 190 | <title>Customizing the /etc/hosts File</title>
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| 191 |
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| 192 | <indexterm zone="ch-scripts-hosts">
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| 193 | <primary sortas="e-/etc/hosts">/etc/hosts</primary>
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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-localnet">localnet</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 | <indexterm zone="ch-scripts-hosts">
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| 202 | <primary sortas="d-network">network</primary>
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| 203 | <secondary>/etc/hosts</secondary>
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| 204 | </indexterm>
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| 205 |
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| 206 | <para>Decide on a fully-qualified domain name (FQDN), and possible aliases
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| 207 | for use in the <filename>/etc/hosts</filename> file. If using static
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| 208 | addresses, you'll also need to decide on an IP address. The syntax
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| 209 | for a hosts file entry is:</para>
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| 210 |
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| 211 | <screen><literal>IP_address myhost.example.org aliases</literal></screen>
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| 212 |
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| 213 | <para>Unless the computer is to be visible to the Internet (i.e., there is
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| 214 | a registered domain and a valid block of assigned IP addresses—most
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| 215 | users do not have this), make sure that the IP address is in the private
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| 216 | network IP address range. Valid ranges are:</para>
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| 217 |
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| 218 | <screen><literal>Private Network Address Range Normal Prefix
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| 219 | 10.0.0.1 - 10.255.255.254 8
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| 220 | 172.x.0.1 - 172.x.255.254 16
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| 221 | 192.168.y.1 - 192.168.y.254 24</literal></screen>
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| 222 |
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| 223 | <para>x can be any number in the range 16-31. y can be any number in the
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| 224 | range 0-255.</para>
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| 225 |
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| 226 | <para>A valid private IP address could be 192.168.1.1. A valid FQDN for
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| 227 | this IP could be lfs.example.org.</para>
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| 228 |
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| 229 | <para>Even if not using a network card, a valid FQDN is still required.
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| 230 | This is necessary for certain programs to operate correctly.</para>
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| 231 |
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| 232 | <para>If using DHCP, DHCPv6, IPv6 Autoconfiguration, or if a network card
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| 233 | is not going to be configured, create the <filename>/etc/hosts</filename>
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| 234 | file by running the following command:</para>
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| 235 |
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| 236 | <screen><userinput>cat > /etc/hosts << "EOF"
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| 237 | <literal># Begin /etc/hosts
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| 238 |
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| 239 | 127.0.0.1 <replaceable><HOSTNAME.example.org></replaceable> <replaceable><HOSTNAME></replaceable> localhost <replaceable>[alias1] [alias2] ...</replaceable>
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| 240 | ::1 <replaceable><HOSTNAME.example.org></replaceable> <replaceable><HOSTNAME></replaceable> localhost <replaceable>[alias1] [alias2] ...</replaceable>
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| 241 |
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| 242 | # End /etc/hosts</literal>
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| 243 | EOF</userinput></screen>
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| 244 |
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| 245 | <para>The ::1 entry is the IPv6 counterpart of 127.0.0.1 and represents
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| 246 | the IPv6 loopback interface.</para>
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| 247 |
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[7eac1a5e] | 248 | <para>If using a staic address, create the <filename>/etc/hosts</filename>
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[1118b17] | 249 | file by running this command instead:</para>
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| 250 |
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| 251 | <screen role="nodump"><userinput>cat > /etc/hosts << "EOF"
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| 252 | <literal># Begin /etc/hosts
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| 253 |
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| 254 | 127.0.0.1 localhost
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| 255 | ::1 localhost
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| 256 | <replaceable><192.168.0.2></replaceable> <replaceable><HOSTNAME.example.org></replaceable> <replaceable><HOSTNAME></replaceable> <replaceable>[alias1] [alias2] ...</replaceable>
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| 257 |
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| 258 | # End /etc/hosts</literal>
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| 259 | EOF</userinput></screen>
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| 260 |
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| 261 | <para>The <replaceable><192.168.0.2></replaceable>,
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| 262 | <replaceable><HOSTNAME.example.org></replaceable>, and
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| 263 | <replaceable><HOSTNAME></replaceable> values need to be
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| 264 | changed for specific uses or requirements (if assigned an IP address by a
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| 265 | network/system administrator and the machine will be connected to an
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| 266 | existing network). The optional alias name(s) can be omitted.</para>
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| 267 |
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| 268 | </sect2>
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| 269 |
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| 270 | </sect1>
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