man/systemd.net-naming-scheme.xml

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   5
   6 <refentry id="systemd.net-naming-scheme">
   7   <refentryinfo>
   8     <title>systemd.net-naming-scheme</title>
   9     <productname>systemd</productname>
  10   </refentryinfo>
  11
  12   <refmeta>
  13     <refentrytitle>systemd.net-naming-scheme</refentrytitle>
  14     <manvolnum>7</manvolnum>
  15   </refmeta>
  16
  17   <refnamediv>
  18     <refname>systemd.net-naming-scheme</refname>
  19     <refpurpose>Network device naming schemes</refpurpose>
  20   </refnamediv>
  21
  22   <refsect1>
  23     <title>Description</title>
  24
  25     <para>Network interfaces names and MAC addresses may be generated based on certain stable interface
  26     attributes. This is possible when there is enough information about the device to generate those
  27     attributes and the use of this information is configured. This page describes interface naming, i.e. what
  28     possible names may be generated. Those names are generated by the
  29     <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  30     builtin <command>net_id</command> and exported as udev properties
  31     (<varname>ID_NET_NAME_ONBOARD=</varname>, <varname>ID_NET_LABEL_ONBOARD=</varname>,
  32     <varname>ID_NET_NAME_PATH=</varname>, <varname>ID_NET_NAME_SLOT=</varname>).</para>
  33
  34     <para>Names and MAC addresses are derived from various stable device metadata attributes. Newer versions
  35     of udev take more of these attributes into account, improving (and thus possibly changing) the names and
  36     addresses used for the same devices. Different versions of those generation rules are called "naming
  37     schemes". The default naming scheme is chosen at compilation time. Usually this will be the latest
  38     implemented version, but it is also possible to set one of the older versions to preserve
  39     compatibility. This may be useful for example for distributions, which may introduce new versions of
  40     systemd in stable releases without changing the naming scheme. The naming scheme may also be overridden
  41     using the <varname>net.naming-scheme=</varname> kernel command line switch, see
  42     <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  43     Available naming schemes are described below.</para>
  44
  45     <para>After the udev properties have been generated, appropriate udev rules may be used to actually rename
  46     devices based on those properties. See the description of <varname>NamePolicy=</varname> and
  47     <varname>MACAddressPolicy=</varname> in
  48     <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
  49
  50     <para>Note that while the concept of network interface naming schemes is primarily relevant in the
  51     context of <filename>systemd-udevd.service</filename>, the
  52     <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  53     container manager also takes it into account when naming network interfaces, see below.</para>
  54   </refsect1>
  55
  56   <refsect1>
  57     <title>Naming</title>
  58
  59     <para>All names start with a two-character prefix that signifies the interface type.</para>
  60
  61     <table>
  62       <title>Two character prefixes based on the type of interface</title>
  63
  64       <tgroup cols='2'>
  65         <thead>
  66           <row>
  67             <entry>Prefix</entry>
  68             <entry>Description</entry>
  69           </row>
  70         </thead>
  71         <tbody>
  72           <row>
  73             <entry><constant>en</constant></entry>
  74             <entry>Ethernet</entry>
  75           </row>
  76           <row>
  77             <entry><constant>ib</constant></entry>
  78             <entry>InfiniBand</entry>
  79           </row>
  80           <row>
  81             <entry><constant>sl</constant></entry>
  82             <entry>Serial line IP (slip)</entry>
  83           </row>
  84           <row>
  85             <entry><constant>wl</constant></entry>
  86             <entry>Wireless local area network (WLAN)</entry>
  87           </row>
  88           <row>
  89             <entry><constant>ww</constant></entry>
  90             <entry>Wireless wide area network (WWAN)</entry>
  91           </row>
  92         </tbody>
  93       </tgroup>
  94     </table>
  95
  96     <para>The udev <command>net_id</command> builtin exports the following udev device properties:</para>
  97
  98     <variablelist>
  99         <varlistentry>
 100           <term><varname>ID_NET_NAME_ONBOARD=<replaceable>prefix</replaceable><constant>o</constant><replaceable>number</replaceable></varname></term>
 101
 102           <listitem><para>This name is set based on the numeric ordering information given by the firmware
 103           for on-board devices. The name consists of the prefix, letter <constant>o</constant>, and a number
 104           specified by the firmware. This is only available for PCI devices.</para>
 105           </listitem>
 106         </varlistentry>
 107
 108         <varlistentry>
 109           <term><varname>ID_NET_LABEL_ONBOARD=<replaceable>prefix</replaceable> <replaceable>label</replaceable></varname></term>
 110
 111           <listitem><para>This property is set based on textual label given by the firmware for on-board
 112           devices. The name consists of the prefix concatenated with the label. This is only available for
 113           PCI devices.
 114           </para>
 115           </listitem>
 116         </varlistentry>
 117
 118         <varlistentry>
 119           <term><varname>ID_NET_NAME_MAC=<replaceable>prefix</replaceable><constant>x</constant><replaceable>AABBCCDDEEFF</replaceable></varname></term>
 120
 121           <listitem><para>This name consists of the prefix, letter <constant>x</constant>, and 12 hexadecimal
 122           digits of the MAC address. It is available if the device has a fixed MAC address. Because this name
 123           is based on an attribute of the card itself, it remains "stable" when the device is moved (even
 124           between machines), but will change when the hardware is replaced.</para>
 125           </listitem>
 126         </varlistentry>
 127
 128         <varlistentry>
 129           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]</varname></term>
 130           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable><constant>v</constant><replaceable>slot</replaceable></varname></term>
 131           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>b</constant><replaceable>number</replaceable></varname></term>
 132           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>u</constant><replaceable>port</replaceable>…[<constant>c</constant><replaceable>config</replaceable>][<constant>i</constant><replaceable>interface</replaceable>]</varname></term>
 133           <term><varname>ID_NET_NAME_SLOT=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>v</constant><replaceable>slot</replaceable></varname></term>
 134
 135           <listitem><para>This property describes the slot position. Different schemes are used depending on
 136           the bus type, as described in the table below. In case of USB, BCMA, and SR-VIO devices, the full
 137           name consists of the prefix, PCI slot identifier, and USB or BCMA or SR-VIO slot identifier. The
 138           first two parts are denoted as "…" in the table below.</para>
 139
 140           <table>
 141             <title>Slot naming schemes</title>
 142
 143             <tgroup cols='2'>
 144               <thead>
 145                 <row>
 146                   <entry>Format</entry>
 147                   <entry>Description</entry>
 148                 </row>
 149               </thead>
 150
 151               <tbody>
 152                 <row>
 153                   <entry><replaceable>prefix</replaceable> [<constant>P</constant><replaceable>domain</replaceable>] <constant>s</constant><replaceable>slot</replaceable> [<constant>f</constant><replaceable>function</replaceable>] [<constant>n</constant><replaceable>port_name</replaceable> | <constant>d</constant><replaceable>dev_port</replaceable>]</entry>
 154                   <entry>PCI slot number</entry>
 155                 </row>
 156
 157                 <row>
 158                   <entry><replaceable>prefix</replaceable> <constant>v</constant><replaceable>slot</replaceable></entry>
 159                   <entry>VIO slot number (IBM PowerVM)</entry>
 160                 </row>
 161
 162                 <row>
 163                   <entry>… <constant>b</constant><replaceable>number</replaceable></entry>
 164                   <entry>Broadcom bus (BCMA) core number</entry>
 165                 </row>
 166
 167                 <row>
 168                   <entry>… <constant>u</constant><replaceable>port</replaceable>… [<constant>c</constant><replaceable>config</replaceable>] [<constant>i</constant><replaceable>interface</replaceable>]</entry>
 169                   <entry>USB port number chain</entry>
 170                 </row>
 171
 172                 <row>
 173                   <entry>… <constant>v</constant><replaceable>slot</replaceable></entry>
 174                   <entry>SR-VIO slot number</entry>
 175                 </row>
 176               </tbody>
 177             </tgroup>
 178           </table>
 179
 180           <para>The PCI domain is only prepended when it is not 0. All multi-function PCI devices will carry
 181           the <constant>f<replaceable>function</replaceable></constant> number in the device name, including
 182           the function 0 device. For non-multi-function devices, the number is suppressed if 0. The port name
 183           <replaceable>port_name</replaceable> is used, or the port number
 184           <constant>d</constant><replaceable>dev_port</replaceable> if the name is not known.</para>
 185
 186           <para>For BCMA devices, the core number is suppressed when 0.</para>
 187
 188           <para>For USB devices the full chain of port numbers of hubs is composed. If the name gets longer
 189           than the maximum number of 15 characters, the name is not exported. The usual USB configuration
 190           number 1 and interface number 0 values are suppressed.</para>
 191
 192           <para>SR-IOV virtual devices are named based on the name of the parent interface, with a suffix of
 193           <constant>v</constant> and the virtual device number, with any leading zeros removed. The bus
 194           number is ignored.</para>
 195           </listitem>
 196         </varlistentry>
 197
 198         <varlistentry>
 199           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>c</constant><replaceable>bus_id</replaceable></varname></term>
 200           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>a</constant><replaceable>vendor</replaceable><replaceable>model</replaceable><constant>i</constant><replaceable>instance</replaceable></varname></term>
 201           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable><constant>i</constant><replaceable>address</replaceable><constant>n</constant><replaceable>port_name</replaceable></varname></term>
 202           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>p</constant><replaceable>bus</replaceable><constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>phys_port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]</varname></term>
 203           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>p</constant><replaceable>bus</replaceable><constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>phys_port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>b</constant><replaceable>number</replaceable></varname></term>
 204           <term><varname>ID_NET_NAME_PATH=<replaceable>prefix</replaceable>[<constant>P</constant><replaceable>domain</replaceable>]<constant>p</constant><replaceable>bus</replaceable><constant>s</constant><replaceable>slot</replaceable>[<constant>f</constant><replaceable>function</replaceable>][<constant>n</constant><replaceable>phys_port_name</replaceable>|<constant>d</constant><replaceable>dev_port</replaceable>]<constant>u</constant><replaceable>port</replaceable>…[<constant>c</constant><replaceable>config</replaceable>][<constant>i</constant><replaceable>interface</replaceable>]</varname></term>
 205
 206           <listitem><para>This property describes the device installation location. Different schemes are
 207           used depending on the bus type, as described in the table below. For BCMA and USB devices, PCI path
 208           information must known, and the full name consists of the prefix, PCI slot identifier, and USB or
 209           BCMA location. The first two parts are denoted as "…" in the table below.</para>
 210
 211           <table>
 212             <title>Path naming schemes</title>
 213
 214             <tgroup cols='2'>
 215               <thead>
 216                 <row>
 217                   <entry>Format</entry>
 218                   <entry>Description</entry>
 219                 </row>
 220               </thead>
 221
 222               <tbody>
 223                 <row>
 224                   <entry><replaceable>prefix</replaceable> <constant>c</constant><replaceable>bus_id</replaceable></entry>
 225                   <entry>CCW or grouped CCW device identifier</entry>
 226                 </row>
 227
 228                 <row>
 229                   <entry><replaceable>prefix</replaceable> <constant>a</constant><replaceable>vendor</replaceable> <replaceable>model</replaceable> <constant>i</constant><replaceable>instance</replaceable></entry>
 230                   <entry>ACPI path names for ARM64 platform devices</entry>
 231                 </row>
 232
 233                 <row>
 234                   <entry><replaceable>prefix</replaceable> <constant>i</constant><replaceable>address</replaceable> <constant>n</constant><replaceable>port_name</replaceable></entry>
 235                   <entry>Netdevsim (simulated networking device) device number and port name</entry>
 236                 </row>
 237
 238                 <row>
 239                   <entry><replaceable>prefix</replaceable> [<constant>P</constant><replaceable>domain</replaceable>] <constant>p</constant><replaceable>bus</replaceable> <constant>s</constant><replaceable>slot</replaceable> [<constant>f</constant><replaceable>function</replaceable>] [<constant>n</constant><replaceable>phys_port_name</replaceable> | <constant>d</constant><replaceable>dev_port</replaceable>]</entry>
 240                   <entry>PCI geographical location</entry>
 241                 </row>
 242
 243                 <row>
 244                   <entry>… <constant>b</constant><replaceable>number</replaceable></entry>
 245                   <entry>Broadcom bus (BCMA) core number</entry>
 246                 </row>
 247
 248                 <row>
 249                   <entry>… <constant>u</constant><replaceable>port</replaceable>… [<constant>c</constant><replaceable>config</replaceable>] [<constant>i</constant><replaceable>interface</replaceable>]</entry>
 250                   <entry>USB port number chain</entry>
 251                 </row>
 252
 253               </tbody>
 254             </tgroup>
 255           </table>
 256
 257           <para>CCW and grouped CCW devices are found in IBM System Z mainframes. Any leading zeros and
 258           dots are suppressed.</para>
 259
 260           <para>For PCI, BCMA, and USB devices, the same rules as described above for slot naming are
 261           used.</para>
 262           </listitem>
 263         </varlistentry>
 264     </variablelist>
 265   </refsect1>
 266
 267   <refsect1>
 268     <title>History</title>
 269
 270     <para>The following "naming schemes" have been defined:</para>
 271
 272     <variablelist>
 273         <varlistentry>
 274           <term><constant>v238</constant></term>
 275
 276           <listitem><para>This is the naming scheme that was implemented in systemd 238.</para></listitem>
 277         </varlistentry>
 278
 279         <varlistentry>
 280           <term><constant>v239</constant></term>
 281
 282           <listitem><para>Naming was changed for virtual network interfaces created with SR-IOV and NPAR and
 283           for devices where the PCI network controller device does not have a slot number associated.</para>
 284
 285           <para>SR-IOV virtual devices are named based on the name of the parent interface, with a suffix of
 286           <literal>v<replaceable>port</replaceable></literal>, where <replaceable>port</replaceable> is the
 287           virtual device number. Previously those virtual devices were named as if completely independent.
 288           </para>
 289
 290           <para>The ninth and later NPAR virtual devices are named following the scheme used for the first
 291           eight NPAR partitions. Previously those devices were not renamed and the kernel default
 292           ("eth<replaceable>N</replaceable>") was used.</para>
 293
 294           <para>Names are also generated for PCI devices where the PCI network controller device does not
 295           have an associated slot number itself, but one of its parents does. Previously those devices were
 296           not renamed and the kernel default was used.</para>
 297           </listitem>
 298         </varlistentry>
 299
 300         <varlistentry>
 301           <term><constant>v240</constant></term>
 302
 303           <listitem><para>The <literal>ib</literal> prefix and stable names for infiniband devices are
 304           introduced. Previously those devices were not renamed.</para>
 305
 306           <para>The ACPI index field (used in <varname>ID_NET_NAME_ONBOARD=</varname>) is now also used when
 307           0.</para>
 308
 309           <para>A new naming policy <varname>NamePolicy=keep</varname> was introduced. With this policy, if
 310           the network device name was already set by userspace, the device will not be renamed
 311           again. Previously, this naming policy applied implicitly, and now it must be explicitly
 312           requested. Effectively, this means that network devices will be renamed according to the
 313           configuration, even if they have been renamed already, if <constant>keep</constant> is not
 314           specified as the naming policy in the <filename index="false">.link</filename> file. See
 315           <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 316           for a description of <varname>NamePolicy=</varname>.</para></listitem>
 317         </varlistentry>
 318
 319         <varlistentry>
 320           <term><constant>v241</constant></term>
 321
 322           <listitem><para><option>MACAddressPolicy=persistent</option> was extended to set MAC addresses
 323           based on the device name. Previously addresses were only based on the
 324           <varname index="false">ID_NET_NAME_*</varname> attributes, which meant that interface names would
 325           never be generated for virtual devices. Now a persistent address will be generated for most
 326           devices, including in particular bridges.</para>
 327
 328           <para>Note: when userspace does not set a MAC address for a bridge device, the kernel will
 329           initially assign a random address, and then change it when the first device is enslaved to the
 330           bridge. With this naming policy change, bridges get a persistent MAC address based on the bridge
 331           name instead of the first enslaved device.</para></listitem>
 332         </varlistentry>
 333
 334         <varlistentry>
 335           <term><constant>v243</constant></term>
 336
 337           <listitem><para>Support for renaming netdevsim (simulated networking) devices was added. Previously
 338           those devices were not renamed.</para>
 339
 340           <para>Previously two-letter interface type prefix was prepended to
 341           <varname>ID_NET_LABEL_ONBOARD=</varname>. This is not done anymore.</para></listitem>
 342         </varlistentry>
 343
 344         <varlistentry>
 345           <term><constant>v245</constant></term>
 346
 347           <listitem><para>When
 348           <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 349           derives the name for the host side of the network interface created with
 350           <option>--network-veth</option> from the container name it previously simply truncated the result
 351           at 15 characters if longer (since that's the maximum length for network interface names). From now
 352           on, for any interface name that would be longer than 15 characters the last 4 characters are set to
 353           a 24bit hash value of the full interface name. This way network interface name collisions between
 354           multiple similarly named containers (who only differ in container name suffix) should be less
 355           likely (but still possible, since the 24bit hash value is very small).</para></listitem>
 356         </varlistentry>
 357       </variablelist>
 358
 359     <para>Note that <constant>latest</constant> may be used to denote the latest scheme known (to this
 360     particular version of systemd).</para>
 361   </refsect1>
 362
 363   <refsect1>
 364     <title>Examples</title>
 365
 366     <example>
 367       <title>Using <command>udevadm test-builtin</command> to display device properties</title>
 368
 369       <programlisting>$ udevadm test-builtin net_id /sys/class/net/enp0s31f6
 370 ...
 371 Using default interface naming scheme 'v243'.
 372 ID_NET_NAMING_SCHEME=v243
 373 ID_NET_NAME_MAC=enx54ee75cb1dc0
 374 ID_OUI_FROM_DATABASE=Wistron InfoComm(Kunshan)Co.,Ltd.
 375 ID_NET_NAME_PATH=enp0s31f6
 376 ...</programlisting>
 377     </example>
 378
 379     <example>
 380       <title>PCI Ethernet card with firmware index "1"</title>
 381
 382       <programlisting>ID_NET_NAME_ONBOARD=eno1
 383 ID_NET_NAME_ONBOARD_LABEL=Ethernet Port 1
 384       </programlisting>
 385     </example>
 386
 387     <example>
 388       <title>PCI Ethernet card in hotplug slot with firmware index number</title>
 389
 390       <programlisting># /sys/devices/pci0000:00/0000:00:1c.3/0000:05:00.0/net/ens1
 391 ID_NET_NAME_MAC=enx000000000466
 392 ID_NET_NAME_PATH=enp5s0
 393 ID_NET_NAME_SLOT=ens1</programlisting>
 394     </example>
 395
 396     <example>
 397       <title>PCI Ethernet multi-function card with 2 ports</title>
 398
 399       <programlisting># /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/net/enp2s0f0
 400 ID_NET_NAME_MAC=enx78e7d1ea46da
 401 ID_NET_NAME_PATH=enp2s0f0
 402
 403 # /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.1/net/enp2s0f1
 404 ID_NET_NAME_MAC=enx78e7d1ea46dc
 405 ID_NET_NAME_PATH=enp2s0f1</programlisting>
 406     </example>
 407
 408     <example>
 409       <title>PCI WLAN card</title>
 410
 411       <programlisting># /sys/devices/pci0000:00/0000:00:1c.1/0000:03:00.0/net/wlp3s0
 412 ID_NET_NAME_MAC=wlx0024d7e31130
 413 ID_NET_NAME_PATH=wlp3s0</programlisting>
 414     </example>
 415
 416     <example>
 417       <title>PCI IB host adapter with 2 ports</title>
 418
 419       <programlisting># /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.0/net/ibp21s0f0
 420 ID_NET_NAME_PATH=ibp21s0f0
 421
 422 # /sys/devices/pci0000:00/0000:00:03.0/0000:15:00.1/net/ibp21s0f1
 423 ID_NET_NAME_PATH=ibp21s0f1</programlisting>
 424     </example>
 425
 426     <example>
 427       <title>USB built-in 3G modem</title>
 428
 429       <programlisting># /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.4/2-1.4:1.6/net/wwp0s29u1u4i6
 430 ID_NET_NAME_MAC=wwx028037ec0200
 431 ID_NET_NAME_PATH=wwp0s29u1u4i6</programlisting>
 432     </example>
 433
 434     <example>
 435       <title>USB Android phone</title>
 436
 437       <programlisting># /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/net/enp0s29u1u2
 438 ID_NET_NAME_MAC=enxd626b3450fb5
 439 ID_NET_NAME_PATH=enp0s29u1u2</programlisting>
 440     </example>
 441
 442     <example>
 443       <title>s390 grouped CCW interface</title>
 444
 445       <programlisting># /sys/devices/css0/0.0.0007/0.0.f5f0/group_device/net/encf5f0
 446 ID_NET_NAME_MAC=enx026d3c00000a
 447 ID_NET_NAME_PATH=encf5f0</programlisting>
 448     </example>
 449   </refsect1>
 450
 451   <refsect1>
 452     <title>See Also</title>
 453     <para>
 454       <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 455       <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 456       <ulink url="https://systemd.io/PREDICTABLE_INTERFACE_NAMES">Predictable Network Interface Names</ulink>,
 457       <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 458     </para>
 459   </refsect1>
 460
 461 </refentry>