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analyze: change behaviour of combined --to/from--pattern
[elogind.git] / man / systemd.link.xml
1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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8   Copyright 2014 Tom Gundersen
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23
24 <refentry id="systemd.link">
25   <refentryinfo>
26     <title>systemd.link</title>
27     <productname>systemd</productname>
28
29     <authorgroup>
30       <author>
31         <contrib>Developer</contrib>
32         <firstname>Tom</firstname>
33         <surname>Gundersen</surname>
34       </author>
35     </authorgroup>
36   </refentryinfo>
37
38   <refmeta>
39     <refentrytitle>systemd.link</refentrytitle>
40     <manvolnum>5</manvolnum>
41   </refmeta>
42
43   <refnamediv>
44     <refname>systemd.link</refname>
45     <refpurpose>Network device configuration</refpurpose>
46   </refnamediv>
47
48   <refsynopsisdiv>
49     <para><filename><replaceable>link</replaceable>.link</filename></para>
50   </refsynopsisdiv>
51
52   <refsect1>
53     <title>Description</title>
54
55     <para>Network link configuration is performed by the
56     <command>net_setup_link</command> udev builtin.</para>
57
58     <para>The link files are read from the files located in the system
59     network directory <filename>/usr/lib/systemd/network</filename>,
60     the volatile runtime network directory
61     <filename>/run/systemd/network</filename>, and the local
62     administration network directory
63     <filename>/etc/systemd/network</filename>. Link files must have
64     the extension <filename>.link</filename>; other extensions are
65     ignored. All link files are collectively sorted and processed in
66     lexical order, regardless of the directories in which they live.
67     However, files with identical filenames replace each other. Files
68     in <filename>/etc</filename> have the highest priority, files in
69     <filename>/run</filename> take precedence over files with the same
70     name in <filename>/usr/lib</filename>. This can be used to
71     override a system-supplied link file with a local file if needed;
72     a symlink in <filename>/etc</filename> with the same name as a
73     link file in <filename>/usr/lib</filename>, pointing to
74     <filename>/dev/null</filename>, disables the link file
75     entirely.</para>
76
77     <para>The link file contains a <literal>[Match]</literal> section,
78     which determines if a given link file may be applied to a given
79     device, as well as a <literal>[Link]</literal> section specifying
80     how the device should be configured. The first (in lexical order)
81     of the link files that matches a given device is applied. Note
82     that a default file <filename>99-default.link</filename> is
83     shipped by the system, any user-supplied
84     <filename>.link</filename> should hence have a lexically earlier
85     name to be considered at all.</para>
86   </refsect1>
87
88   <refsect1>
89     <title>[Match] Section Options</title>
90
91     <para>A link file is said to match a device if each of the entries
92     in the <literal>[Match]</literal> section matches, or if the
93     section is empty. The following keys are accepted:</para>
94
95     <variablelist class='network-directives'>
96       <varlistentry>
97         <term><varname>MACAddress=</varname></term>
98         <listitem>
99           <para>The hardware address.</para>
100         </listitem>
101       </varlistentry>
102       <varlistentry>
103         <term><varname>OriginalName=</varname></term>
104         <listitem>
105           <para>A whitespace-separated list of shell-style globs matching
106           the device name, as exposed by the udev property
107           "INTERFACE". This can not be used to match on names that have
108           already been changed from userspace. Caution is advised when matching on
109           kernel-assigned names, as they are known to be unstable
110           between reboots.</para>
111         </listitem>
112       </varlistentry>
113       <varlistentry>
114         <term><varname>Path=</varname></term>
115         <listitem>
116           <para>A whitespace-separated list of shell-style globs matching
117           the persistent path, as exposed by the udev property
118           <literal>ID_PATH</literal>.</para>
119         </listitem>
120       </varlistentry>
121       <varlistentry>
122         <term><varname>Driver=</varname></term>
123         <listitem>
124           <para>A whitespace-separated list of shell-style globs matching
125           the driver currently bound to the device,
126           as exposed by the udev property <literal>DRIVER</literal>
127           of its parent device, or if that is not set, the
128           driver as exposed by <literal>ethtool -i</literal>
129           of the device itself.</para>
130         </listitem>
131       </varlistentry>
132       <varlistentry>
133         <term><varname>Type=</varname></term>
134         <listitem>
135           <para>A whitespace-separated list of shell-style globs matching
136           the device type, as exposed by the udev
137           property <literal>DEVTYPE</literal>.</para>
138         </listitem>
139       </varlistentry>
140       <varlistentry>
141         <term><varname>Host=</varname></term>
142         <listitem>
143           <para>Matches against the hostname or machine
144           ID of the host. See <literal>ConditionHost=</literal> in
145           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
146           for details.</para>
147         </listitem>
148       </varlistentry>
149       <varlistentry>
150         <term><varname>Virtualization=</varname></term>
151         <listitem>
152           <para>Checks whether the system is executed in
153           a virtualized environment and optionally test
154           whether it is a specific implementation. See
155           <literal>ConditionVirtualization=</literal> in
156           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
157           for details.</para>
158         </listitem>
159       </varlistentry>
160       <varlistentry>
161         <term><varname>KernelCommandLine=</varname></term>
162         <listitem>
163           <para>Checks whether a specific kernel command line option
164           is set (or if prefixed with the exclamation mark unset). See
165           <literal>ConditionKernelCommandLine=</literal> in
166           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
167           for details.</para>
168         </listitem>
169       </varlistentry>
170       <varlistentry>
171         <term><varname>Architecture=</varname></term>
172         <listitem>
173           <para>Checks whether the system is running on a specific
174           architecture. See <literal>ConditionArchitecture=</literal>
175           in
176           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
177           for details.</para>
178         </listitem>
179       </varlistentry>
180     </variablelist>
181
182   </refsect1>
183
184   <refsect1>
185     <title>[Link] Section Options</title>
186
187     <para>The <literal>[Link]</literal> section accepts the following
188     keys:</para>
189
190     <variablelist class='network-directives'>
191       <varlistentry>
192         <term><varname>Description=</varname></term>
193         <listitem>
194           <para>A description of the device.</para>
195         </listitem>
196       </varlistentry>
197       <varlistentry>
198         <term><varname>Alias=</varname></term>
199         <listitem>
200           <para>The <literal>ifalias</literal> is set to this
201           value.</para>
202         </listitem>
203       </varlistentry>
204       <varlistentry>
205         <term><varname>MACAddressPolicy=</varname></term>
206         <listitem>
207           <para>The policy by which the MAC address should be set. The
208           available policies are:
209           </para>
210
211           <variablelist>
212             <varlistentry>
213               <term><literal>persistent</literal></term>
214               <listitem>
215                 <para>If the hardware has a persistent MAC address, as
216                 most hardware should, and if it is used by the kernel,
217                 nothing is done. Otherwise, a new MAC address is
218                 generated which is guaranteed to be the same on every
219                 boot for the given machine and the given device, but
220                 which is otherwise random. This feature depends on ID_NET_NAME_*
221                 properties existing for the link, on hardware where these
222                 properties are not set the generation of a persistent MAC address
223                 will fail.</para>
224               </listitem>
225             </varlistentry>
226             <varlistentry>
227               <term><literal>random</literal></term>
228               <listitem>
229                 <para>If the kernel is using a random MAC address,
230                 nothing is done. Otherwise, a new address is randomly
231                 generated each time the device appears, typically at
232                 boot.</para>
233               </listitem>
234             </varlistentry>
235           </variablelist>
236         </listitem>
237       </varlistentry>
238       <varlistentry>
239         <term><varname>MACAddress=</varname></term>
240         <listitem>
241           <para>The MAC address to use, if no
242           <literal>MACAddressPolicy=</literal>
243           is specified.</para>
244         </listitem>
245       </varlistentry>
246       <varlistentry>
247         <term><varname>NamePolicy=</varname></term>
248         <listitem>
249           <para>An ordered, space-separated list of policies by which
250           the interface name should be set.
251           <literal>NamePolicy</literal> may be disabled by specifying
252           <literal>net.ifnames=0</literal> on the kernel command line.
253           Each of the policies may fail, and the first successful one
254           is used. The name is not set directly, but is exported to
255           udev as the property <literal>ID_NET_NAME</literal>, which
256           is, by default, used by a udev rule to set
257           <literal>NAME</literal>. If the name has already been set by
258           userspace, no renaming is performed. The available policies
259           are:</para>
260
261           <variablelist>
262             <varlistentry>
263               <term><literal>kernel</literal></term>
264               <listitem>
265                 <para>If the kernel claims that the name it has set
266                 for a device is predictable, then no renaming is
267                 performed.</para>
268               </listitem>
269             </varlistentry>
270             <varlistentry>
271               <term><literal>database</literal></term>
272               <listitem>
273                 <para>The name is set based on entries in the udev's
274                 Hardware Database with the key
275                 <literal>ID_NET_NAME_FROM_DATABASE</literal>.
276                 </para>
277               </listitem>
278             </varlistentry>
279             <varlistentry>
280               <term><literal>onboard</literal></term>
281               <listitem>
282                 <para>The name is set based on information given by
283                 the firmware for on-board devices, as exported by the
284                 udev property <literal>ID_NET_NAME_ONBOARD</literal>.
285                 </para>
286               </listitem>
287             </varlistentry>
288             <varlistentry>
289               <term><literal>slot</literal></term>
290               <listitem>
291                 <para>The name is set based on information given by
292                 the firmware for hot-plug devices, as exported by the
293                 udev property <literal>ID_NET_NAME_SLOT</literal>.
294                 </para>
295               </listitem>
296             </varlistentry>
297             <varlistentry>
298               <term><literal>path</literal></term>
299               <listitem>
300                 <para>The name is set based on the device's physical
301                 location, as exported by the udev property
302                 <literal>ID_NET_NAME_PATH</literal>.</para>
303               </listitem>
304             </varlistentry>
305             <varlistentry>
306               <term><literal>mac</literal></term>
307               <listitem>
308                 <para>The name is set based on the device's persistent
309                 MAC address, as exported by the udev property
310                 <literal>ID_NET_NAME_MAC</literal>.</para>
311               </listitem>
312             </varlistentry>
313           </variablelist>
314         </listitem>
315       </varlistentry>
316       <varlistentry>
317         <term><varname>Name=</varname></term>
318         <listitem>
319           <para>The interface name to use in case all the
320           policies specified in
321           <varname>NamePolicy=</varname> fail, or in case
322           <varname>NamePolicy=</varname> is missing or
323           disabled.</para>
324         </listitem>
325       </varlistentry>
326       <varlistentry>
327         <term><varname>MTUBytes=</varname></term>
328         <listitem>
329           <para>The maximum transmission unit in bytes to set for the
330           device. The usual suffixes K, M, G, are supported and are
331           understood to the base of 1024.</para>
332         </listitem>
333       </varlistentry>
334       <varlistentry>
335         <term><varname>BitsPerSecond=</varname></term>
336         <listitem>
337           <para>The speed to set for the device, the value is rounded
338           down to the nearest Mbps. The usual suffixes K, M, G, are
339           supported and are understood to the base of 1000.</para>
340         </listitem>
341       </varlistentry>
342       <varlistentry>
343         <term><varname>Duplex=</varname></term>
344         <listitem>
345           <para>The duplex mode to set for the device. The accepted
346           values are <literal>half</literal> and
347           <literal>full</literal>.</para>
348         </listitem>
349       </varlistentry>
350       <varlistentry>
351         <term><varname>WakeOnLan=</varname></term>
352         <listitem>
353           <para>The Wake-on-LAN policy to set for the device. The
354           supported values are:</para>
355
356           <variablelist>
357             <varlistentry>
358               <term><literal>phy</literal></term>
359               <listitem>
360                 <para>Wake on PHY activity.</para>
361               </listitem>
362             </varlistentry>
363             <varlistentry>
364               <term><literal>magic</literal></term>
365               <listitem>
366                 <para>Wake on receipt of a magic packet.
367                 </para>
368               </listitem>
369             </varlistentry>
370             <varlistentry>
371               <term><literal>off</literal></term>
372               <listitem>
373                 <para>Never wake.</para>
374               </listitem>
375             </varlistentry>
376           </variablelist>
377         </listitem>
378       </varlistentry>
379     </variablelist>
380   </refsect1>
381
382   <refsect1>
383     <title>Example</title>
384     <example>
385       <title>/etc/systemd/network/wireless.link</title>
386
387       <programlisting>[Match]
388 MACAddress=12:34:56:78:9a:bc
389 Driver=brcmsmac
390 Path=pci-0000:02:00.0-*
391 Type=wlan
392 Virtualization=no
393 Host=my-laptop
394 Architecture=x86-64
395
396 [Link]
397 Name=wireless0
398 MTUBytes=1450
399 BitsPerSecond=10M
400 WakeOnLan=magic
401 MACAddress=cb:a9:87:65:43:21</programlisting>
402     </example>
403   </refsect1>
404
405   <refsect1>
406     <title>See Also</title>
407     <para>
408       <citerefentry>
409         <refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum>
410       </citerefentry>,
411       <citerefentry>
412         <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum>
413       </citerefentry>,
414       <citerefentry>
415         <refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum>
416       </citerefentry>,
417       <citerefentry>
418         <refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum>
419       </citerefentry>
420     </para>
421   </refsect1>
422
423 </refentry>