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| Copyright 2014 Tom Gundersen |
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| |
| <refentry id="systemd.link"> |
| <refentryinfo> |
| <title>systemd.link</title> |
| <productname>systemd</productname> |
| |
| <authorgroup> |
| <author> |
| <contrib>Developer</contrib> |
| <firstname>Tom</firstname> |
| <surname>Gundersen</surname> |
| </author> |
| </authorgroup> |
| </refentryinfo> |
| |
| <refmeta> |
| <refentrytitle>systemd.link</refentrytitle> |
| <manvolnum>5</manvolnum> |
| </refmeta> |
| |
| <refnamediv> |
| <refname>systemd.link</refname> |
| <refpurpose>Network device configuration</refpurpose> |
| </refnamediv> |
| |
| <refsynopsisdiv> |
| <para><filename><replaceable>link</replaceable>.link</filename></para> |
| </refsynopsisdiv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para>Network link configuration is performed by the <command>net_setup_link</command> |
| udev builtin.</para> |
| |
| <para>The link files are read from the files located in the |
| system network directory <filename>/usr/lib/systemd/network</filename>, |
| the volatile runtime network directory <filename>/run/systemd/network</filename>, |
| and the local administration network directory <filename>/etc/systemd/network</filename>. |
| Link files must have the extension <filename>.link</filename>; other extensions are ignored. |
| All link files are collectively sorted and processed in lexical order, |
| regardless of the directories in which they live. However, files with |
| identical filenames replace each other. Files in <filename>/etc</filename> |
| have the highest priority, files in <filename>/run</filename> take precedence |
| over files with the same name in <filename>/usr/lib</filename>. This can be |
| used to override a system-supplied link file with a local file if needed; |
| a symlink in <filename>/etc</filename> with the same name as a link file in |
| <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>, |
| disables the link file entirely.</para> |
| |
| <para>The link file contains a <literal>[Match]</literal> section, which |
| determines if a given link file may be applied to a given device; and a |
| <literal>[Link]</literal> section specifying how the device should be |
| configured. The first (in lexical order) of the link files that matches |
| a given device is applied.</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>[Match] Section Options</title> |
| |
| <para>A link file is said to match a device if each of the entries in the |
| <literal>[Match]</literal> section matches, or if the section is empty. |
| The following keys are accepted:</para> |
| |
| <variablelist class='network-directives'> |
| <varlistentry> |
| <term><varname>MACAddress=</varname></term> |
| <listitem> |
| <para>The hardware address.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>OriginalName=</varname></term> |
| <listitem> |
| <para>The device name, as exposed by the udev |
| property "INTERFACE". May contain shell style |
| globs. This can not be used to match on names |
| that have already been changed from userspace. |
| Caution is adviced when matching on |
| kernel-assigned names, as they are known to |
| be unstable between reboots.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>Path=</varname></term> |
| <listitem> |
| <para>The persistent path, as exposed by the |
| udev property <literal>ID_PATH</literal>. May |
| contain shell style globs.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>Driver=</varname></term> |
| <listitem> |
| <para>The driver currently bound to the device, |
| as exposed by the udev property <literal>DRIVER</literal> |
| of its parent device, or if that is not set, the |
| driver as exposed by <literal>ethtool -i</literal> |
| of the device itself.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>Type=</varname></term> |
| <listitem> |
| <para>The device type, as exposed by the udev |
| property <literal>DEVTYPE</literal>.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>Host=</varname></term> |
| <listitem> |
| <para>Matches against the hostname or machine |
| ID of the host. See <literal>ConditionHost=</literal> in |
| <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
| for details.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>Virtualization=</varname></term> |
| <listitem> |
| <para>Checks whether the system is executed in |
| a virtualized environment and optionally test |
| whether it is a specific implementation. See |
| <literal>ConditionVirtualization=</literal> in |
| <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
| for details.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>KernelCommandLine=</varname></term> |
| <listitem> |
| <para>Checks whether a specific kernel command |
| line option is set (or if prefixed with the |
| exclamation mark unset). See |
| <literal>ConditionKernelCommandLine=</literal> in |
| <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
| for details.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>Architecture=</varname></term> |
| <listitem> |
| <para>Checks whether the system is running on a |
| specific architecture. See |
| <literal>ConditionArchitecture=</literal> in |
| <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
| for details.</para> |
| </listitem> |
| </varlistentry> |
| </variablelist> |
| |
| </refsect1> |
| |
| <refsect1> |
| <title>[Link] Section Options</title> |
| |
| <para>The <literal>[Link]</literal> section accepts the following |
| keys:</para> |
| |
| <variablelist class='network-directives'> |
| <varlistentry> |
| <term><varname>Description=</varname></term> |
| <listitem> |
| <para>A description of the device.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>Alias=</varname></term> |
| <listitem> |
| <para>The <literal>ifalias</literal> is set to |
| this value.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>MACAddressPolicy=</varname></term> |
| <listitem> |
| <para>The policy by which the MAC address |
| should be set. The available policies are: |
| </para> |
| |
| <variablelist> |
| <varlistentry> |
| <term><literal>persistent</literal></term> |
| <listitem> |
| <para>If the hardware has a persistent |
| MAC address, as most hardware should, |
| and if it is used by the kernel, nothing |
| is done. Otherwise, a new MAC address |
| is generated which is guaranteed to be |
| the same on every boot for the given |
| machine and the given device, but which |
| is otherwise random.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><literal>random</literal></term> |
| <listitem> |
| <para>If the kernel is using a random MAC |
| address, nothing is done. Otherwise, a new |
| address is randomly generated each time the |
| device appears, typically at boot.</para> |
| </listitem> |
| </varlistentry> |
| </variablelist> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>MACAddress=</varname></term> |
| <listitem> |
| <para>The MAC address to use, if no |
| <literal>MACAddressPolicy=</literal> |
| is specified.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>NamePolicy=</varname></term> |
| <listitem> |
| <para>An ordered, space-separated list of |
| policies by which the interface name should |
| be set. <literal>NamePolicy</literal> may be |
| disabled by specifying |
| <literal>net.ifnames=0</literal> on the kernel |
| command line. Each of the policies may fail, and |
| the first successful one is used. The name is |
| not set directly, but is exported to udev as |
| the property <literal>ID_NET_NAME</literal>, |
| which is, by default, used by a udev rule to set |
| <literal>NAME</literal>. If the name has already |
| been set by userspace, no renaming is performed. |
| The available policies are:</para> |
| |
| <variablelist> |
| <varlistentry> |
| <term><literal>kernel</literal></term> |
| <listitem> |
| <para>If the kernel claims that the name it |
| has set for a device is predictable, then |
| no renaming is performed. |
| </para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><literal>database</literal></term> |
| <listitem> |
| <para>The name is set based on entries in |
| the udev's Hardware Database with the key |
| <literal>ID_NET_NAME_FROM_DATABASE</literal>. |
| </para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><literal>onboard</literal></term> |
| <listitem> |
| <para>The name is set based on information given by |
| the firmware for on-board devices, as exported by |
| the udev property <literal>ID_NET_NAME_ONBOARD</literal>. |
| </para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><literal>slot</literal></term> |
| <listitem> |
| <para>The name is set based on information given by |
| the firmware for hot-plug devices, as exported by |
| the udev property <literal>ID_NET_NAME_SLOT</literal>. |
| </para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><literal>path</literal></term> |
| <listitem> |
| <para>The name is set based on the device's physical |
| location, as exported by the udev property |
| <literal>ID_NET_NAME_PATH</literal>.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><literal>mac</literal></term> |
| <listitem> |
| <para>The name is set based on the device's |
| persistent MAC address, as exported by the udev |
| property <literal>ID_NET_NAME_MAC</literal>.</para> |
| </listitem> |
| </varlistentry> |
| </variablelist> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>Name=</varname></term> |
| <listitem> |
| <para>The interface name to use in case all the |
| policies specified in |
| <varname>NamePolicy=</varname> fail, or in case |
| <varname>NamePolicy=</varname> is missing or |
| disabled.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>MTUBytes=</varname></term> |
| <listitem> |
| <para>The maximum transmission unit in bytes to |
| set for the device. The usual suffixes K, M, G, |
| are supported and are understood to the base of |
| 1024.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>BitsPerSecond=</varname></term> |
| <listitem> |
| <para>The speed to set for the device, the |
| value is rounded down to the nearest Mbps. |
| The usual suffixes K, M, G, are supported and |
| are understood to the base of 1000.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>Duplex=</varname></term> |
| <listitem> |
| <para>The duplex mode to set for the device. |
| The accepted values are <literal>half</literal> |
| and <literal>full</literal>.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><varname>WakeOnLan=</varname></term> |
| <listitem> |
| <para>The Wake-on-LAN policy to set for the |
| device. The supported values are:</para> |
| |
| <variablelist> |
| <varlistentry> |
| <term><literal>phy</literal></term> |
| <listitem> |
| <para>Wake on PHY activity.</para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><literal>magic</literal></term> |
| <listitem> |
| <para>Wake on receipt of a magic packet. |
| </para> |
| </listitem> |
| </varlistentry> |
| <varlistentry> |
| <term><literal>off</literal></term> |
| <listitem> |
| <para>Never wake.</para> |
| </listitem> |
| </varlistentry> |
| </variablelist> |
| </listitem> |
| </varlistentry> |
| </variablelist> |
| </refsect1> |
| |
| <refsect1> |
| <title>Example</title> |
| <example> |
| <title>/etc/systemd/network/wireless.link</title> |
| |
| <programlisting>[Match] |
| MACAddress=12:34:56:78:9a:bc |
| Driver=brcmsmac |
| Path=pci-0000:02:00.0-* |
| Type=wlan |
| Virtualization=no |
| Host=my-laptop |
| Architecture=x86-64 |
| |
| [Link] |
| Name=wireless0 |
| MTUBytes=1450 |
| BitsPerSecond=10M |
| WakeOnLan=magic |
| MACAddress=cb:a9:87:65:43:21</programlisting> |
| </example> |
| </refsect1> |
| |
| <refsect1> |
| <title>See Also</title> |
| <para> |
| <citerefentry> |
| <refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum> |
| </citerefentry>, |
| <citerefentry> |
| <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum> |
| </citerefentry> |
| </para> |
| </refsect1> |
| |
| </refentry> |