source: chapter09/networkd.xml@ c53ff08

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systemd: network configuration: network-manager is now compatible with systemd-resolved

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1<?xml version="1.0" encoding="ISO-8859-1"?>
2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
4 <!ENTITY % general-entities SYSTEM "../general.ent">
5 %general-entities;
6]>
7
8<sect1 id="ch-config-network" revision="systemd">
9 <?dbhtml filename="network.html"?>
10
11 <title>General Network Configuration</title>
12
13 <indexterm zone="ch-config-network">
14 <primary sortas="d-network">network</primary>
15 <secondary>configuring</secondary></indexterm>
16
17 <para>This section only applies if a network card is to be
18 configured.</para>
19
20 <sect2>
21 <title>Network Interface Configuration Files</title>
22
23 <para>Starting with version 209, systemd ships a network configuration
24 daemon called <command>systemd-networkd</command> which can be used for
25 basic network configuration. Additionally, since version 213, DNS name
26 resolution can be handled by <command>systemd-resolved</command> in place
27 of a static <filename>/etc/resolv.conf</filename> file. Both services are
28 enabled by default.</para>
29
30 <para>Configuration files for <command>systemd-networkd</command> (and
31 <command>systemd-resolved</command>) can be placed in
32 <filename class="directory">/usr/lib/systemd/network</filename>
33 or <filename class="directory">/etc/systemd/network</filename>. Files in
34 <filename class="directory">/etc/systemd/network</filename> have a
35 higher priority than the ones in
36 <filename class="directory">/usr/lib/systemd/network</filename>.
37 There are three types of configuration files:
38 <filename class="extension">.link</filename>,
39 <filename class="extension">.netdev</filename> and
40 <filename class="extension">.network</filename> files. For detailed
41 descriptions and example contents of these configuration files, consult
42 the <filename>systemd-link(5)</filename>,
43 <filename>systemd-netdev(5)</filename> and
44 <filename>systemd-network(5)</filename> manual pages.</para>
45
46 <sect3 id="systemd-network-devices">
47 <title>Network Device Naming</title>
48
49 <para>
50 Udev normally assigns network card interface names based
51 on physical system characteristics such as enp2s1. If you are
52 not sure what your interface name is, you can always run
53 <command>ip link</command> after you have booted your system.
54 </para>
55
56 <para>
57 For most systems, there is only one network interface for
58 each type of connection. For example, the classic interface
59 name for a wired connection is eth0. A wireless connection
60 will usually have the name wifi0 or wlan0.
61 </para>
62
63 <para>
64 If you prefer to use the classic or customized network interface names,
65 there are three alternative ways to do that:</para>
66
67 <itemizedlist>
68 <listitem>
69 <para>
70 Mask udev's .link file for the default policy:
71<screen role="nodump"><userinput>ln -s /dev/null /etc/systemd/network/99-default.link</userinput></screen>
72 </para>
73 </listitem>
74
75 <listitem>
76 <para>
77 Create a manual naming scheme, for example by naming the
78 interfaces something like "internet0", "dmz0", or "lan0".
79 To do that, create .link files in /etc/systemd/network/ that
80 select an explicit name or a better naming scheme for your
81 network interfaces. For example:
82 </para>
83
84<screen role="nodump"><userinput>cat &gt; /etc/systemd/network/10-ether0.link &lt;&lt; "EOF"
85<literal>[Match]
86# Change the MAC address as appropriate for your network device
87MACAddress=12:34:45:78:90:AB
88
89[Link]
90Name=ether0</literal>
91EOF</userinput></screen>
92
93 <para>
94 See the man page systemd.link(5) for more information.
95 </para>
96 </listitem>
97
98 <listitem>
99 <para>
100 In /boot/grub/grub.cfg, pass the option net.ifnames=0 on the
101 kernel command line.
102 </para>
103 </listitem>
104 </itemizedlist>
105 </sect3>
106
107 <sect3 id="systemd-networkd-static">
108 <title>Static IP Configuration</title>
109
110 <para>The command below creates a basic configuration file for a
111 Static IP setup (using both systemd-networkd and
112 systemd-resolved):</para>
113<!-- jhalfs relies on the values for Name, Address, etc. If you want to change
114 them, please inform the jhalfs maintainer(s). -->
115<screen><userinput>cat &gt; /etc/systemd/network/10-eth-static.network &lt;&lt; "EOF"
116<literal>[Match]
117Name=<replaceable>&lt;network-device-name&gt;</replaceable>
118
119[Network]
120Address=192.168.0.2/24
121Gateway=192.168.0.1
122DNS=192.168.0.1
123Domains=<replaceable>&lt;Your Domain Name&gt;</replaceable></literal>
124EOF</userinput></screen>
125
126 <para>Multiple DNS entries can be added if you have more than one DNS
127 server. Do not include DNS or Domains entries if you intend to use a
128 static <filename>/etc/resolv.conf</filename> file.</para>
129
130 </sect3>
131
132 <sect3 id="systemd-networkd-dhcp">
133 <title>DHCP Configuration</title>
134
135 <para>The command below creates a basic configuration file for an IPv4
136 DHCP setup:</para>
137
138<screen role="nodump"><userinput>cat &gt; /etc/systemd/network/10-eth-dhcp.network &lt;&lt; "EOF"
139<literal>[Match]
140Name=&lt;network-device-name&gt;
141
142[Network]
143DHCP=ipv4
144
145[DHCP]
146UseDomains=true</literal>
147EOF</userinput></screen>
148
149 </sect3>
150
151 </sect2>
152
153 <sect2 id="resolv.conf">
154 <title>Creating the /etc/resolv.conf File</title>
155
156 <indexterm zone="resolv.conf">
157 <primary sortas="e-/etc/resolv.conf">/etc/resolv.conf</primary>
158 </indexterm>
159
160 <para>If the system is going to be connected to the Internet, it will
161 need some means of Domain Name Service (DNS) name resolution to
162 resolve Internet domain names to IP addresses, and vice versa. This is
163 best achieved by placing the IP address of the DNS server, available
164 from the ISP or network administrator, into
165 <filename>/etc/resolv.conf</filename>.</para>
166
167 <sect3 id="resolv-conf-systemd-resolved">
168 <title>systemd-resolved Configuration</title>
169
170 <note><para>If using methods incompatible with systemd-resolved to
171 configure your network interfaces (ex: ppp, etc.), or if using any
172 type of local resolver (ex: bind, dnsmasq, unbound, etc.),
173 or any other software that generates an <filename>/etc/resolv.conf</filename>
174 (ex: a <command>resolvconf</command> program other than the one
175 provided by systemd), the <command>systemd-resolved</command> service
176 should not be used.</para></note>
177
178 <para>When using <command>systemd-resolved</command> for DNS
179 configuration, it creates the file
180 <filename>/run/systemd/resolve/resolv.conf</filename>. Create a
181 symlink in <filename>/etc</filename> to use the generated file:</para>
182
183<screen><userinput>ln -sfv /run/systemd/resolve/resolv.conf /etc/resolv.conf</userinput></screen>
184
185 </sect3>
186
187 <sect3 id="resolv-conf-static">
188 <title>Static resolv.conf Configuration</title>
189
190 <para>If a static <filename>/etc/resolv.conf</filename> is desired,
191 create it by running the following command:</para>
192
193<screen role="nodump"><userinput>cat &gt; /etc/resolv.conf &lt;&lt; "EOF"
194<literal># Begin /etc/resolv.conf
195
196domain <replaceable>&lt;Your Domain Name&gt;</replaceable>
197nameserver <replaceable>&lt;IP address of your primary nameserver&gt;</replaceable>
198nameserver <replaceable>&lt;IP address of your secondary nameserver&gt;</replaceable>
199
200# End /etc/resolv.conf</literal>
201EOF</userinput></screen>
202
203 <para>The <varname>domain</varname> statement can be omitted
204 or replaced with a <varname>search</varname> statement. See the man page
205 for resolv.conf for more details.</para>
206
207 <para>Replace
208 <replaceable>&lt;IP address of the nameserver&gt;</replaceable>
209 with the IP address of the DNS server most appropriate for your setup.
210 There will often be more than one entry (requirements demand secondary
211 servers for fallback capability). If you only need or want one DNS server,
212 remove the second <emphasis>nameserver</emphasis> line from the file.
213 The IP address may also be a router on the local network. Another option
214 is to use the Google Public DNS service using the IP addresses below as
215 nameservers.</para>
216
217 <note><para>The Google Public IPv4 DNS addresses are
218 <parameter>8.8.8.8</parameter> and <parameter>8.8.4.4</parameter>
219 for IPv4, and <parameter>2001:4860:4860::8888</parameter> and
220 <parameter>2001:4860:4860::8844</parameter> for IPv6.</para></note>
221
222 </sect3>
223
224 </sect2>
225
226 <sect2 id="ch-config-hostname">
227 <title>Configuring the system hostname</title>
228
229 <indexterm zone="ch-config-hostname">
230 <primary sortas="d-hostname">hostname</primary>
231 <secondary>configuring</secondary>
232 </indexterm>
233
234 <para>During the boot process, the file <filename>/etc/hostname</filename>
235 is used for establishing the system's hostname.</para>
236
237 <para>Create the <filename>/etc/hostname</filename> file and enter a
238 hostname by running:</para>
239
240<screen><userinput>echo "<replaceable>&lt;lfs&gt;</replaceable>" &gt; /etc/hostname</userinput></screen>
241
242 <para><replaceable>&lt;lfs&gt;</replaceable> needs to be replaced with the
243 name given to the computer. Do not enter the Fully Qualified Domain Name
244 (FQDN) here. That information is put in the
245 <filename>/etc/hosts</filename> file.</para>
246
247 </sect2>
248
249 <sect2 id="ch-config-hosts">
250 <title>Customizing the /etc/hosts File</title>
251
252 <indexterm zone="ch-config-hosts">
253 <primary sortas="e-/etc/hosts">/etc/hosts</primary>
254 </indexterm>
255
256 <indexterm zone="ch-config-hosts">
257 <primary sortas="d-localnet">localnet</primary>
258 <secondary>/etc/hosts</secondary>
259 </indexterm>
260
261 <indexterm zone="ch-config-hosts">
262 <primary sortas="d-network">network</primary>
263 <secondary>/etc/hosts</secondary>
264 </indexterm>
265
266 <para>Decide on a fully-qualified domain name (FQDN), and possible aliases
267 for use in the <filename>/etc/hosts</filename> file. If using static IP
268 addresses, you'll also need to decide on an IP address. The syntax
269 for a hosts file entry is:</para>
270
271<screen><literal>IP_address myhost.example.org aliases</literal></screen>
272
273 <para>Unless the computer is to be visible to the Internet (i.e., there is
274 a registered domain and a valid block of assigned IP addresses&mdash;most
275 users do not have this), make sure that the IP address is in the private
276 network IP address range. Valid ranges are:</para>
277
278<screen><literal>Private Network Address Range Normal Prefix
27910.0.0.1 - 10.255.255.254 8
280172.x.0.1 - 172.x.255.254 16
281192.168.y.1 - 192.168.y.254 24</literal></screen>
282
283 <para>x can be any number in the range 16-31. y can be any number in the
284 range 0-255.</para>
285
286 <para>A valid private IP address could be 192.168.1.1. A valid FQDN for
287 this IP could be lfs.example.org.</para>
288
289 <para>Even if not using a network card, a valid FQDN is still required.
290 This is necessary for certain programs, such as MTAs, to operate properly.</para>
291
292<!--
293 <para>Create the /etc/hosts file using the following command:</para>
294
295<screen role="nodump"><userinput>cat &gt; /etc/hosts &lt;&lt; "EOF"
296<literal># Begin /etc/hosts
297
298127.0.0.1 localhost.localdomain localhost
299127.0.1.1 <replaceable>&lt;FQDN&gt;</replaceable> <replaceable>&lt;HOSTNAME&gt;</replaceable>
300::1 localhost ip6-localhost ip6-loopback
301ff02::1 ip6-allnodes
302ff02::2 ip6-allrouters
303
304# End /etc/hosts</literal>
305EOF</userinput></screen>
306-->
307
308 <para>Create the <filename>/etc/hosts</filename> file using the following
309 command:</para>
310
311<screen><userinput>cat &gt; /etc/hosts &lt;&lt; "EOF"
312<literal># Begin /etc/hosts
313
314127.0.0.1 localhost.localdomain localhost
315127.0.1.1 <replaceable>&lt;FQDN&gt;</replaceable> <replaceable>&lt;HOSTNAME&gt;</replaceable>
316<replaceable>&lt;192.168.0.2&gt;</replaceable> <replaceable>&lt;FQDN&gt;</replaceable> <replaceable>&lt;HOSTNAME&gt;</replaceable> <replaceable>[alias1] [alias2] ...</replaceable>
317::1 localhost ip6-localhost ip6-loopback
318ff02::1 ip6-allnodes
319ff02::2 ip6-allrouters
320
321# End /etc/hosts</literal>
322EOF</userinput></screen>
323
324 <para>The <replaceable>&lt;192.168.0.2&gt;</replaceable>,
325 <replaceable>&lt;FQDN&gt;</replaceable>, and
326 <replaceable>&lt;HOSTNAME&gt;</replaceable> values need to be
327 changed for specific uses or requirements (if assigned an IP address by a
328 network/system administrator and the machine will be connected to an
329 existing network). The optional alias name(s) can be omitted, and the
330 <replaceable>&lt;192.168.0.2</replaceable> line can be omitted if you
331 are using a connection configured with DHCP or IPv6 Autoconfiguration.</para>
332
333 <para>The ::1 entry is the IPv6 counterpart of 127.0.0.1 and represents
334 the IPv6 loopback interface. 127.0.1.1 is a loopback entry reserved
335 specifically for the FQDN.</para>
336
337 </sect2>
338
339</sect1>
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