man/systemd.netdev.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refentry id="systemd.netdev" conditional='ENABLE_NETWORKD'>
   7
   8   <refentryinfo>
   9     <title>systemd.network</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>systemd.netdev</refentrytitle>
  15     <manvolnum>5</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>systemd.netdev</refname>
  20     <refpurpose>Virtual Network Device configuration</refpurpose>
  21   </refnamediv>
  22
  23   <refsynopsisdiv>
  24     <para><filename><replaceable>netdev</replaceable>.netdev</filename></para>
  25   </refsynopsisdiv>
  26
  27   <refsect1>
  28     <title>Description</title>
  29
  30     <para>Network setup is performed by
  31     <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  32     </para>
  33
  34     <para>The main Virtual Network Device file must have the extension <filename>.netdev</filename>;
  35     other extensions are ignored. Virtual network devices are created as soon as networkd is
  36     started. If a netdev with the specified name already exists, networkd will use that as-is rather
  37     than create its own. Note that the settings of the pre-existing netdev will not be changed by
  38     networkd.</para>
  39
  40     <para>The <filename>.netdev</filename> files are read from the files located in the system
  41     network directory <filename>/usr/lib/systemd/network</filename>, the volatile runtime network
  42     directory <filename>/run/systemd/network</filename> and the local administration network
  43     directory <filename>/etc/systemd/network</filename>. All configuration files are collectively
  44     sorted and processed in lexical order, regardless of the directories in which they live.
  45     However, files with identical filenames replace each other. Files in <filename>/etc</filename>
  46     have the highest priority, files in <filename>/run</filename> take precedence over files with
  47     the same name in <filename>/usr/lib</filename>. This can be used to override a system-supplied
  48     configuration file with a local file if needed. As a special case, an empty file (file size 0)
  49     or symlink with the same name pointing to <filename>/dev/null</filename> disables the
  50     configuration file entirely (it is "masked").</para>
  51
  52     <para>Along with the netdev file <filename>foo.netdev</filename>, a "drop-in" directory
  53     <filename>foo.netdev.d/</filename> may exist. All files with the suffix <literal>.conf</literal>
  54     from this directory will be parsed after the file itself is parsed. This is useful to alter or
  55     add configuration settings, without having to modify the main configuration file. Each drop-in
  56     file must have appropriate section headers.</para>
  57
  58     <para>In addition to <filename>/etc/systemd/network</filename>, drop-in <literal>.d</literal>
  59     directories can be placed in <filename>/usr/lib/systemd/network</filename> or
  60     <filename>/run/systemd/network</filename> directories. Drop-in files in
  61     <filename>/etc</filename> take precedence over those in <filename>/run</filename> which in turn
  62     take precedence over those in <filename>/usr/lib</filename>. Drop-in files under any of these
  63     directories take precedence over the main netdev file wherever located. (Of course, since
  64     <filename>/run</filename> is temporary and <filename>/usr/lib</filename> is for vendors, it is
  65     unlikely drop-ins should be used in either of those places.)</para>
  66   </refsect1>
  67
  68   <refsect1>
  69     <title>Supported netdev kinds</title>
  70
  71     <para>The following kinds of virtual network devices may be
  72     configured in <filename>.netdev</filename> files:</para>
  73
  74     <table>
  75       <title>Supported kinds of virtual network devices</title>
  76
  77       <tgroup cols='2'>
  78         <colspec colname='kind' />
  79         <colspec colname='explanation' />
  80         <thead><row>
  81           <entry>Kind</entry>
  82           <entry>Description</entry>
  83         </row></thead>
  84         <tbody>
  85           <row><entry><varname>bond</varname></entry>
  86           <entry>A bond device is an aggregation of all its slave devices. See <ulink url="https://www.kernel.org/doc/Documentation/networking/bonding.txt">Linux Ethernet Bonding Driver HOWTO</ulink> for details.Local configuration</entry></row>
  87
  88           <row><entry><varname>bridge</varname></entry>
  89           <entry>A bridge device is a software switch, and each of its slave devices and the bridge itself are ports of the switch.</entry></row>
  90
  91           <row><entry><varname>dummy</varname></entry>
  92           <entry>A dummy device drops all packets sent to it.</entry></row>
  93
  94           <row><entry><varname>gre</varname></entry>
  95           <entry>A Level 3 GRE tunnel over IPv4. See <ulink url="https://tools.ietf.org/html/rfc2784">RFC 2784</ulink> for details.</entry></row>
  96
  97           <row><entry><varname>gretap</varname></entry>
  98           <entry>A Level 2 GRE tunnel over IPv4.</entry></row>
  99
 100           <row><entry><varname>erspan</varname></entry>
 101           <entry>ERSPAN mirrors traffic on one or more source ports and delivers the mirrored traffic to one or more destination ports on another switch. The traffic is encapsulated in generic routing encapsulation (GRE) and is therefore routable across a layer 3 network between the source switch and the destination switch.</entry></row>
 102
 103           <row><entry><varname>ip6gre</varname></entry>
 104           <entry>A Level 3 GRE tunnel over IPv6.</entry></row>
 105
 106           <row><entry><varname>ip6tnl</varname></entry>
 107           <entry>An IPv4 or IPv6 tunnel over IPv6</entry></row>
 108
 109           <row><entry><varname>ip6gretap</varname></entry>
 110           <entry>A Level 2 GRE tunnel over IPv6.</entry></row>
 111
 112           <row><entry><varname>ipip</varname></entry>
 113           <entry>An IPv4 over IPv4 tunnel.</entry></row>
 114
 115           <row><entry><varname>ipvlan</varname></entry>
 116           <entry>An ipvlan device is a stacked device which receives packets from its underlying device based on IP address filtering.</entry></row>
 117
 118           <row><entry><varname>ipvtap</varname></entry>
 119           <entry>An ipvtap device is a stacked device which receives packets from its underlying device based on IP address filtering and can be accessed using the tap user space interface.</entry></row>
 120
 121           <row><entry><varname>macvlan</varname></entry>
 122           <entry>A macvlan device is a stacked device which receives packets from its underlying device based on MAC address filtering.</entry></row>
 123
 124           <row><entry><varname>macvtap</varname></entry>
 125           <entry>A macvtap device is a stacked device which receives packets from its underlying device based on MAC address filtering.</entry></row>
 126
 127           <row><entry><varname>sit</varname></entry>
 128           <entry>An IPv6 over IPv4 tunnel.</entry></row>
 129
 130           <row><entry><varname>tap</varname></entry>
 131           <entry>A persistent Level 2 tunnel between a network device and a device node.</entry></row>
 132
 133           <row><entry><varname>tun</varname></entry>
 134           <entry>A persistent Level 3 tunnel between a network device and a device node.</entry></row>
 135
 136           <row><entry><varname>veth</varname></entry>
 137           <entry>An Ethernet tunnel between a pair of network devices.</entry></row>
 138
 139           <row><entry><varname>vlan</varname></entry>
 140           <entry>A VLAN is a stacked device which receives packets from its underlying device based on VLAN tagging. See <ulink url="http://www.ieee802.org/1/pages/802.1Q.html">IEEE 802.1Q</ulink> for details.</entry></row>
 141
 142           <row><entry><varname>vti</varname></entry>
 143           <entry>An IPv4 over IPSec tunnel.</entry></row>
 144
 145           <row><entry><varname>vti6</varname></entry>
 146           <entry>An IPv6 over IPSec tunnel.</entry></row>
 147
 148           <row><entry><varname>vxlan</varname></entry>
 149           <entry>A virtual extensible LAN (vxlan), for connecting Cloud computing deployments.</entry></row>
 150
 151           <row><entry><varname>geneve</varname></entry>
 152           <entry>A GEneric NEtwork Virtualization Encapsulation (GENEVE) netdev driver.</entry></row>
 153
 154           <row><entry><varname>l2tp</varname></entry>
 155           <entry>A Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs) or as part of the delivery of services by ISPs. It does not provide any encryption or confidentiality by itself</entry></row>
 156
 157           <row><entry><varname>macsec</varname></entry>
 158           <entry>Media Access Control Security (MACsec) is an 802.1AE IEEE industry-standard security technology that provides secure communication for all traffic on Ethernet links. MACsec provides point-to-point security on Ethernet links between directly connected nodes and is capable of identifying and preventing most security threats.</entry></row>
 159
 160           <row><entry><varname>vrf</varname></entry>
 161           <entry>A Virtual Routing and Forwarding (<ulink url="https://www.kernel.org/doc/Documentation/networking/vrf.txt">VRF</ulink>) interface to create separate routing and forwarding domains.</entry></row>
 162
 163           <row><entry><varname>vcan</varname></entry>
 164           <entry>The virtual CAN driver (vcan). Similar to the network loopback devices, vcan offers a virtual local CAN interface.</entry></row>
 165
 166           <row><entry><varname>vxcan</varname></entry>
 167           <entry>The virtual CAN tunnel driver (vxcan). Similar to the virtual ethernet driver veth, vxcan implements a local CAN traffic tunnel between two virtual CAN network devices. When creating a vxcan, two vxcan devices are created as pair. When one end receives the packet it appears on its pair and vice versa. The vxcan can be used for cross namespace communication.
 168           </entry></row>
 169
 170           <row><entry><varname>wireguard</varname></entry>
 171           <entry>WireGuard Secure Network Tunnel.</entry></row>
 172
 173           <row><entry><varname>netdevsim</varname></entry>
 174           <entry> A simulator. This simulated networking device is used for testing various networking APIs and at this time is particularly focused on testing hardware offloading related interfaces.</entry></row>
 175
 176           <row><entry><varname>fou</varname></entry>
 177           <entry>Foo-over-UDP tunneling.</entry></row>
 178
 179         </tbody>
 180       </tgroup>
 181     </table>
 182
 183   </refsect1>
 184
 185   <refsect1>
 186     <title>[Match] Section Options</title>
 187
 188     <para>A virtual network device is only created if the
 189     <literal>[Match]</literal> section matches the current
 190     environment, or if the section is empty. The following keys are
 191     accepted:</para>
 192
 193     <variablelist class='network-directives'>
 194       <varlistentry>
 195         <term><varname>Host=</varname></term>
 196         <listitem>
 197           <para>Matches against the hostname or machine ID of the host. See
 198           <literal>ConditionHost=</literal> in
 199           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 200           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 201           If an empty string is assigned, then previously assigned value is cleared.
 202           </para>
 203         </listitem>
 204       </varlistentry>
 205       <varlistentry>
 206         <term><varname>Virtualization=</varname></term>
 207         <listitem>
 208           <para>Checks whether the system is executed in a virtualized environment and optionally test
 209           whether it is a specific implementation. See <literal>ConditionVirtualization=</literal> in
 210           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 211           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 212           If an empty string is assigned, then previously assigned value is cleared.
 213           </para>
 214         </listitem>
 215       </varlistentry>
 216       <varlistentry>
 217         <term><varname>KernelCommandLine=</varname></term>
 218         <listitem>
 219           <para>Checks whether a specific kernel command line option is set. See
 220           <literal>ConditionKernelCommandLine=</literal> in
 221           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 222           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 223           If an empty string is assigned, then previously assigned value is cleared.
 224           </para>
 225         </listitem>
 226       </varlistentry>
 227       <varlistentry>
 228         <term><varname>KernelVersion=</varname></term>
 229         <listitem>
 230           <para>Checks whether the kernel version (as reported by <command>uname -r</command>) matches a
 231           certain expression. See <literal>ConditionKernelVersion=</literal> in
 232           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 233           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 234           If an empty string is assigned, then previously assigned value is cleared.
 235           </para>
 236         </listitem>
 237       </varlistentry>
 238       <varlistentry>
 239         <term><varname>Architecture=</varname></term>
 240         <listitem>
 241           <para>Checks whether the system is running on a specific architecture. See
 242           <literal>ConditionArchitecture=</literal> in
 243           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 244           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 245           If an empty string is assigned, then previously assigned value is cleared.
 246           </para>
 247         </listitem>
 248       </varlistentry>
 249     </variablelist>
 250
 251   </refsect1>
 252
 253   <refsect1>
 254     <title>[NetDev] Section Options</title>
 255
 256       <para>The <literal>[NetDev]</literal> section accepts the
 257       following keys:</para>
 258
 259       <variablelist class='network-directives'>
 260         <varlistentry>
 261           <term><varname>Description=</varname></term>
 262           <listitem>
 263             <para>A free-form description of the netdev.</para>
 264           </listitem>
 265         </varlistentry>
 266         <varlistentry>
 267           <term><varname>Name=</varname></term>
 268           <listitem>
 269             <para>The interface name used when creating the netdev.
 270             This option is compulsory.</para>
 271           </listitem>
 272         </varlistentry>
 273         <varlistentry>
 274           <term><varname>Kind=</varname></term>
 275           <listitem>
 276             <para>The netdev kind. This option is compulsory. See the
 277             <literal>Supported netdev kinds</literal> section for the
 278             valid keys.</para>
 279           </listitem>
 280         </varlistentry>
 281         <varlistentry>
 282           <term><varname>MTUBytes=</varname></term>
 283           <listitem>
 284             <para>The maximum transmission unit in bytes to set for the device. The usual suffixes K, M, G,
 285             are supported and are understood to the base of 1024. For <literal>tun</literal> or
 286             <literal>tap</literal> devices, <varname>MTUBytes=</varname> setting is not currently supported in
 287             <literal>[NetDev]</literal> section. Please specify it in <literal>[Link]</literal> section of
 288             corresponding
 289             <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 290             files.</para>
 291           </listitem>
 292         </varlistentry>
 293         <varlistentry>
 294           <term><varname>MACAddress=</varname></term>
 295           <listitem>
 296             <para>The MAC address to use for the device. For <literal>tun</literal> or <literal>tap</literal>
 297             devices, setting <varname>MACAddress=</varname> in the <literal>[NetDev]</literal> section is not
 298             supported. Please specify it in <literal>[Link]</literal> section of the corresponding
 299             <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 300             file. If this option is not set, <literal>vlan</literal> devices inherit the MAC address of the
 301             physical interface. For other kind of netdevs, if this option is not set, then MAC address is
 302             generated based on the interface name and the
 303             <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 304             </para>
 305           </listitem>
 306         </varlistentry>
 307       </variablelist>
 308   </refsect1>
 309
 310     <refsect1>
 311     <title>[Bridge] Section Options</title>
 312
 313       <para>The <literal>[Bridge]</literal> section only applies for
 314       netdevs of kind <literal>bridge</literal>, and accepts the
 315       following keys:</para>
 316
 317       <variablelist class='network-directives'>
 318         <varlistentry>
 319           <term><varname>HelloTimeSec=</varname></term>
 320           <listitem>
 321             <para>HelloTimeSec specifies the number of seconds between two hello packets
 322             sent out by the root bridge and the designated bridges. Hello packets are
 323             used to communicate information about the topology throughout the entire
 324             bridged local area network.</para>
 325           </listitem>
 326         </varlistentry>
 327         <varlistentry>
 328           <term><varname>MaxAgeSec=</varname></term>
 329           <listitem>
 330             <para>MaxAgeSec specifies the number of seconds of maximum message age.
 331             If the last seen (received) hello packet is more than this number of
 332             seconds old, the bridge in question will start the takeover procedure
 333             in attempt to become the Root Bridge itself.</para>
 334           </listitem>
 335         </varlistentry>
 336         <varlistentry>
 337           <term><varname>ForwardDelaySec=</varname></term>
 338           <listitem>
 339             <para>ForwardDelaySec specifies the number of seconds spent in each
 340             of the Listening and Learning states before the Forwarding state is entered.</para>
 341           </listitem>
 342         </varlistentry>
 343         <varlistentry>
 344           <term><varname>AgeingTimeSec=</varname></term>
 345           <listitem>
 346             <para>This specifies the number of seconds a MAC Address will be kept in
 347             the forwarding database after having a packet received from this MAC Address.</para>
 348           </listitem>
 349         </varlistentry>
 350         <varlistentry>
 351           <term><varname>Priority=</varname></term>
 352           <listitem>
 353             <para>The priority of the bridge. An integer between 0 and 65535. A lower value
 354             means higher priority. The bridge having the lowest priority will be elected as root bridge.</para>
 355           </listitem>
 356         </varlistentry>
 357         <varlistentry>
 358           <term><varname>GroupForwardMask=</varname></term>
 359           <listitem>
 360             <para>A 16-bit bitmask represented as an integer which allows forwarding of link
 361             local frames with 802.1D reserved addresses (01:80:C2:00:00:0X). A logical AND
 362             is performed between the specified bitmask and the exponentiation of 2^X, the
 363             lower nibble of the last octet of the MAC address. For example, a value of 8
 364             would allow forwarding of frames addressed to 01:80:C2:00:00:03 (802.1X PAE).</para>
 365           </listitem>
 366         </varlistentry>
 367         <varlistentry>
 368           <term><varname>DefaultPVID=</varname></term>
 369           <listitem>
 370             <para>This specifies the default port VLAN ID of a newly attached bridge port.
 371             Set this to an integer in the range 1–4094 or <literal>none</literal> to disable the PVID.</para>
 372           </listitem>
 373         </varlistentry>
 374         <varlistentry>
 375           <term><varname>MulticastQuerier=</varname></term>
 376           <listitem>
 377             <para>Takes a boolean. This setting controls the IFLA_BR_MCAST_QUERIER option in the kernel.
 378             If enabled, the kernel will send general ICMP queries from a zero source address.
 379             This feature should allow faster convergence on startup, but it causes some
 380             multicast-aware switches to misbehave and disrupt forwarding of multicast packets.
 381             When unset, the kernel's default will be used.
 382             </para>
 383           </listitem>
 384         </varlistentry>
 385         <varlistentry>
 386           <term><varname>MulticastSnooping=</varname></term>
 387           <listitem>
 388             <para>Takes a boolean. This setting controls the IFLA_BR_MCAST_SNOOPING option in the kernel.
 389             If enabled, IGMP snooping monitors the Internet Group Management Protocol (IGMP) traffic
 390             between hosts and multicast routers. When unset, the kernel's default will be used.
 391             </para>
 392           </listitem>
 393         </varlistentry>
 394         <varlistentry>
 395           <term><varname>VLANFiltering=</varname></term>
 396           <listitem>
 397             <para>Takes a boolean. This setting controls the IFLA_BR_VLAN_FILTERING option in the kernel.
 398             If enabled, the bridge will be started in VLAN-filtering mode. When unset, the kernel's default will be used.
 399             </para>
 400           </listitem>
 401         </varlistentry>
 402           <varlistentry>
 403           <term><varname>STP=</varname></term>
 404           <listitem>
 405             <para>Takes a boolean. This enables the bridge's Spanning Tree Protocol (STP).
 406             When unset, the kernel's default will be used.
 407             </para>
 408           </listitem>
 409         </varlistentry>
 410       </variablelist>
 411   </refsect1>
 412
 413   <refsect1>
 414     <title>[VLAN] Section Options</title>
 415
 416       <para>The <literal>[VLAN]</literal> section only applies for
 417       netdevs of kind <literal>vlan</literal>, and accepts the
 418       following key:</para>
 419
 420       <variablelist class='network-directives'>
 421         <varlistentry>
 422           <term><varname>Id=</varname></term>
 423           <listitem>
 424             <para>The VLAN ID to use. An integer in the range 0–4094.
 425             This option is compulsory.</para>
 426           </listitem>
 427         </varlistentry>
 428         <varlistentry>
 429           <term><varname>GVRP=</varname></term>
 430           <listitem>
 431             <para>Takes a boolean. The Generic VLAN Registration Protocol (GVRP) is a protocol that
 432             allows automatic learning of VLANs on a network.
 433             When unset, the kernel's default will be used.
 434             </para>
 435           </listitem>
 436         </varlistentry>
 437         <varlistentry>
 438           <term><varname>MVRP=</varname></term>
 439           <listitem>
 440             <para>Takes a boolean. Multiple VLAN Registration Protocol (MVRP) formerly known as GARP VLAN
 441             Registration Protocol (GVRP) is a standards-based Layer 2 network protocol,
 442             for automatic configuration of VLAN information on switches. It was defined
 443             in the 802.1ak amendment to 802.1Q-2005. When unset, the kernel's default will be used.
 444             </para>
 445           </listitem>
 446         </varlistentry>
 447         <varlistentry>
 448           <term><varname>LooseBinding=</varname></term>
 449           <listitem>
 450             <para>Takes a boolean. The VLAN loose binding mode, in which only the operational state is passed
 451             from the parent to the associated VLANs, but the VLAN device state is not changed.
 452             When unset, the kernel's default will be used.</para>
 453           </listitem>
 454         </varlistentry>
 455         <varlistentry>
 456           <term><varname>ReorderHeader=</varname></term>
 457           <listitem>
 458             <para>Takes a boolean. The VLAN reorder header is set VLAN interfaces behave like physical interfaces.
 459             When unset, the kernel's default will be used.</para>
 460           </listitem>
 461         </varlistentry>
 462       </variablelist>
 463   </refsect1>
 464
 465   <refsect1>
 466     <title>[MACVLAN] Section Options</title>
 467
 468     <para>The <literal>[MACVLAN]</literal> section only applies for
 469     netdevs of kind <literal>macvlan</literal>, and accepts the
 470     following key:</para>
 471
 472     <variablelist class='network-directives'>
 473       <varlistentry>
 474         <term><varname>Mode=</varname></term>
 475         <listitem>
 476           <para>The MACVLAN mode to use. The supported options are
 477           <literal>private</literal>,
 478           <literal>vepa</literal>,
 479           <literal>bridge</literal>, and
 480           <literal>passthru</literal>.
 481           </para>
 482         </listitem>
 483       </varlistentry>
 484     </variablelist>
 485
 486   </refsect1>
 487
 488     <refsect1>
 489     <title>[MACVTAP] Section Options</title>
 490
 491     <para>The <literal>[MACVTAP]</literal> section applies for
 492     netdevs of kind <literal>macvtap</literal> and accepts the
 493     same key as <literal>[MACVLAN]</literal>.</para>
 494
 495     </refsect1>
 496
 497   <refsect1>
 498     <title>[IPVLAN] Section Options</title>
 499
 500     <para>The <literal>[IPVLAN]</literal> section only applies for
 501     netdevs of kind <literal>ipvlan</literal>, and accepts the
 502     following key:</para>
 503
 504     <variablelist class='network-directives'>
 505       <varlistentry>
 506         <term><varname>Mode=</varname></term>
 507           <listitem>
 508             <para>The IPVLAN mode to use. The supported options are
 509             <literal>L2</literal>,<literal>L3</literal> and <literal>L3S</literal>.
 510             </para>
 511           </listitem>
 512       </varlistentry>
 513        <varlistentry>
 514         <term><varname>Flags=</varname></term>
 515           <listitem>
 516             <para>The IPVLAN flags to use. The supported options are
 517             <literal>bridge</literal>,<literal>private</literal> and <literal>vepa</literal>.
 518             </para>
 519           </listitem>
 520       </varlistentry>
 521     </variablelist>
 522
 523   </refsect1>
 524
 525   <refsect1>
 526     <title>[IPVTAP] Section Options</title>
 527
 528     <para>The <literal>[IPVTAP]</literal> section only applies for
 529     netdevs of kind <literal>ipvtap</literal> and accepts the
 530     same key as <literal>[IPVLAN]</literal>.</para>
 531
 532   </refsect1>
 533
 534   <refsect1>
 535     <title>[VXLAN] Section Options</title>
 536     <para>The <literal>[VXLAN]</literal> section only applies for
 537     netdevs of kind <literal>vxlan</literal>, and accepts the
 538     following keys:</para>
 539
 540     <variablelist class='network-directives'>
 541       <varlistentry>
 542         <term><varname>VNI=</varname></term>
 543         <listitem>
 544           <para>The VXLAN Network Identifier (or VXLAN Segment ID). Takes a number in the range 1-16777215.</para>
 545         </listitem>
 546       </varlistentry>
 547       <varlistentry>
 548         <term><varname>Remote=</varname></term>
 549         <listitem>
 550           <para>Configures destination IP address.</para>
 551         </listitem>
 552       </varlistentry>
 553       <varlistentry>
 554         <term><varname>Local=</varname></term>
 555         <listitem>
 556           <para>Configures local IP address.</para>
 557         </listitem>
 558       </varlistentry>
 559       <varlistentry>
 560         <term><varname>Group=</varname></term>
 561         <listitem>
 562           <para>Configures VXLAN multicast group IP address. All members of a VXLAN must use the same multicast group address.</para>
 563         </listitem>
 564       </varlistentry>
 565         <varlistentry>
 566         <term><varname>TOS=</varname></term>
 567         <listitem>
 568           <para>The Type Of Service byte value for a vxlan interface.</para>
 569         </listitem>
 570       </varlistentry>
 571       <varlistentry>
 572         <term><varname>TTL=</varname></term>
 573         <listitem>
 574           <para>A fixed Time To Live N on Virtual eXtensible Local Area Network packets.
 575           Takes <literal>inherit</literal> or a number in the range 0–255. 0 is a special
 576           value meaning inherit the inner protocol's TTL value. <literal>inherit</literal>
 577           means that it will inherit the outer protocol's TTL value.</para>
 578         </listitem>
 579       </varlistentry>
 580       <varlistentry>
 581         <term><varname>MacLearning=</varname></term>
 582         <listitem>
 583           <para>Takes a boolean. When true, enables dynamic MAC learning
 584           to discover remote MAC addresses.</para>
 585         </listitem>
 586       </varlistentry>
 587       <varlistentry>
 588         <term><varname>FDBAgeingSec=</varname></term>
 589         <listitem>
 590           <para>The lifetime of Forwarding Database entry learnt by
 591           the kernel, in seconds.</para>
 592         </listitem>
 593       </varlistentry>
 594       <varlistentry>
 595         <term><varname>MaximumFDBEntries=</varname></term>
 596         <listitem>
 597           <para>Configures maximum number of FDB entries.</para>
 598         </listitem>
 599       </varlistentry>
 600       <varlistentry>
 601         <term><varname>ReduceARPProxy=</varname></term>
 602         <listitem>
 603           <para>Takes a boolean. When true, bridge-connected VXLAN tunnel
 604           endpoint answers ARP requests from the local bridge on behalf
 605           of remote Distributed Overlay Virtual Ethernet
 606           <ulink url="https://en.wikipedia.org/wiki/Distributed_Overlay_Virtual_Ethernet">
 607           (DVOE)</ulink> clients. Defaults to false.</para>
 608         </listitem>
 609       </varlistentry>
 610       <varlistentry>
 611         <term><varname>L2MissNotification=</varname></term>
 612         <listitem>
 613           <para>Takes a boolean. When true, enables netlink LLADDR miss
 614           notifications.</para>
 615         </listitem>
 616       </varlistentry>
 617       <varlistentry>
 618         <term><varname>L3MissNotification=</varname></term>
 619         <listitem>
 620           <para>Takes a boolean. When true, enables netlink IP address miss
 621           notifications.</para>
 622         </listitem>
 623       </varlistentry>
 624       <varlistentry>
 625         <term><varname>RouteShortCircuit=</varname></term>
 626         <listitem>
 627           <para>Takes a boolean. When true, route short circuiting is turned
 628           on.</para>
 629         </listitem>
 630       </varlistentry>
 631       <varlistentry>
 632         <term><varname>UDPChecksum=</varname></term>
 633         <listitem>
 634           <para>Takes a boolean. When true, transmitting UDP checksums when doing VXLAN/IPv4 is turned on.</para>
 635         </listitem>
 636       </varlistentry>
 637       <varlistentry>
 638         <term><varname>UDP6ZeroChecksumTx=</varname></term>
 639         <listitem>
 640           <para>Takes a boolean. When true, sending zero checksums in VXLAN/IPv6 is turned on.</para>
 641         </listitem>
 642       </varlistentry>
 643       <varlistentry>
 644         <term><varname>UDP6ZeroChecksumRx=</varname></term>
 645         <listitem>
 646           <para>Takes a boolean. When true, receiving zero checksums in VXLAN/IPv6 is turned on.</para>
 647         </listitem>
 648       </varlistentry>
 649       <varlistentry>
 650         <term><varname>RemoteChecksumTx=</varname></term>
 651         <listitem>
 652           <para>Takes a boolean. When true, remote transmit checksum offload of VXLAN is turned on.</para>
 653         </listitem>
 654       </varlistentry>
 655       <varlistentry>
 656         <term><varname>RemoteChecksumRx=</varname></term>
 657         <listitem>
 658           <para>Takes a boolean. When true, remote receive checksum offload in VXLAN is turned on.</para>
 659         </listitem>
 660       </varlistentry>
 661     <varlistentry>
 662       <term><varname>GroupPolicyExtension=</varname></term>
 663       <listitem>
 664         <para>Takes a boolean. When true, it enables Group Policy VXLAN extension security label mechanism
 665         across network peers based on VXLAN. For details about the Group Policy VXLAN, see the
 666         <ulink url="https://tools.ietf.org/html/draft-smith-vxlan-group-policy">
 667         VXLAN Group Policy </ulink> document. Defaults to false.</para>
 668       </listitem>
 669     </varlistentry>
 670     <varlistentry>
 671        <term><varname>GenericProtocolExtension=</varname></term>
 672        <listitem>
 673          <para>Takes a boolean. When true, Generic Protocol Extension extends the existing VXLAN protocol
 674          to provide protocol typing, OAM, and versioning capabilities. For details about the VXLAN GPE
 675          Header, see the <ulink url="https://tools.ietf.org/html/draft-ietf-nvo3-vxlan-gpe-07">
 676          Generic Protocol Extension for VXLAN </ulink> document. If destination port is not specified and
 677          Generic Protocol Extension is set then default port of 4790 is used. Defaults to false.</para>
 678        </listitem>
 679     </varlistentry>
 680     <varlistentry>
 681       <term><varname>DestinationPort=</varname></term>
 682       <listitem>
 683         <para>Configures the default destination UDP port on a per-device basis.
 684         If destination port is not specified then Linux kernel default will be used.
 685         Set destination port 4789 to get the IANA assigned value. If not set or if the
 686         destination port is assigned the empty string the default port of 4789 is used.</para>
 687       </listitem>
 688     </varlistentry>
 689     <varlistentry>
 690       <term><varname>PortRange=</varname></term>
 691         <listitem>
 692           <para>Configures VXLAN port range. VXLAN bases source
 693           UDP port based on flow to help the receiver to be able
 694           to load balance based on outer header flow. It
 695           restricts the port range to the normal UDP local
 696           ports, and allows overriding via configuration.</para>
 697         </listitem>
 698       </varlistentry>
 699     <varlistentry>
 700       <term><varname>FlowLabel=</varname></term>
 701         <listitem>
 702           <para>Specifies the flow label to use in outgoing packets.
 703           The valid range is 0-1048575.
 704           </para>
 705         </listitem>
 706     </varlistentry>
 707       <varlistentry>
 708         <term><varname>IPDoNotFragment=</varname></term>
 709         <listitem>
 710           <para>Allows to set the IPv4 Do not Fragment (DF) bit in outgoing packets, or to inherit its
 711           value from the IPv4 inner header. Takes a boolean value, or <literal>inherit</literal>. Set
 712           to <literal>inherit</literal> if the encapsulated protocol is IPv6. When unset, the kernel's
 713           default will be used.</para>
 714         </listitem>
 715       </varlistentry>
 716     </variablelist>
 717   </refsect1>
 718   <refsect1>
 719     <title>[GENEVE] Section Options</title>
 720     <para>The <literal>[GENEVE]</literal> section only applies for
 721     netdevs of kind <literal>geneve</literal>, and accepts the
 722     following keys:</para>
 723
 724     <variablelist class='network-directives'>
 725       <varlistentry>
 726         <term><varname>Id=</varname></term>
 727         <listitem>
 728           <para>Specifies the Virtual Network Identifier (VNI) to use. Ranges [0-16777215]. This field is mandatory.</para>
 729         </listitem>
 730       </varlistentry>
 731       <varlistentry>
 732         <term><varname>Remote=</varname></term>
 733         <listitem>
 734           <para>Specifies the unicast destination IP address to use in outgoing packets.</para>
 735         </listitem>
 736       </varlistentry>
 737       <varlistentry>
 738         <term><varname>TOS=</varname></term>
 739         <listitem>
 740           <para>Specifies the TOS value to use in outgoing packets. Ranges [1-255].</para>
 741         </listitem>
 742       </varlistentry>
 743       <varlistentry>
 744         <term><varname>TTL=</varname></term>
 745         <listitem>
 746           <para>Accepts the same key in <literal>[VXLAN]</literal> section except when unset or
 747           set to 0, the kernel's default will be used meaning that packets TTL will be set from
 748           <filename>/proc/sys/net/ipv4/ip_default_ttl</filename>.</para>
 749         </listitem>
 750       </varlistentry>
 751       <varlistentry>
 752         <term><varname>UDPChecksum=</varname></term>
 753         <listitem>
 754           <para>Takes a boolean. When true, specifies if UDP checksum is calculated for transmitted packets over IPv4.</para>
 755         </listitem>
 756       </varlistentry>
 757       <varlistentry>
 758         <term><varname>UDP6ZeroChecksumTx=</varname></term>
 759         <listitem>
 760           <para>Takes a boolean. When true, skip UDP checksum calculation for transmitted packets over IPv6.</para>
 761         </listitem>
 762       </varlistentry>
 763       <varlistentry>
 764         <term><varname>UDP6ZeroChecksumRx=</varname></term>
 765         <listitem>
 766           <para>Takes a boolean. When true, allows incoming UDP packets over IPv6 with zero checksum field.</para>
 767         </listitem>
 768       </varlistentry>
 769     <varlistentry>
 770       <term><varname>DestinationPort=</varname></term>
 771       <listitem>
 772         <para>Specifies destination port. Defaults to 6081. If not set or assigned the empty string, the default
 773         port of 6081 is used.</para>
 774       </listitem>
 775     </varlistentry>
 776     <varlistentry>
 777       <term><varname>FlowLabel=</varname></term>
 778         <listitem>
 779           <para>Specifies the flow label to use in outgoing packets.</para>
 780         </listitem>
 781     </varlistentry>
 782     <varlistentry>
 783       <term><varname>IPDoNotFragment=</varname></term>
 784         <listitem>
 785           <para>Accepts the same key in <literal>[VXLAN]</literal> section.</para>
 786         </listitem>
 787     </varlistentry>
 788     </variablelist>
 789   </refsect1>
 790   <refsect1>
 791     <title>[L2TP] Section Options</title>
 792     <para>The <literal>[L2TP]</literal> section only applies for
 793     netdevs of kind <literal>l2tp</literal>, and accepts the
 794     following keys:</para>
 795
 796     <variablelist class='network-directives'>
 797       <varlistentry>
 798         <term><varname>TunnelId=</varname></term>
 799         <listitem>
 800           <para>Specifies the tunnel id. The value used must match the <literal>PeerTunnelId=</literal> value being used at the peer.
 801           Ranges a number between 1 and 4294967295). This option is compulsory.</para>
 802         </listitem>
 803       </varlistentry>
 804       <varlistentry>
 805         <term><varname>PeerTunnelId=</varname></term>
 806         <listitem>
 807           <para>Specifies the peer tunnel id. The value used must match the <literal>PeerTunnelId=</literal> value being used at the peer.
 808           Ranges a number between 1 and 4294967295). This option is compulsory.</para>
 809         </listitem>
 810       </varlistentry>
 811       <varlistentry>
 812         <term><varname>Remote=</varname></term>
 813         <listitem>
 814           <para>Specifies the IP address of the remote peer. This option is compulsory.</para>
 815         </listitem>
 816       </varlistentry>
 817       <varlistentry>
 818         <term><varname>Local=</varname></term>
 819         <listitem>
 820           <para>Specifies the IP address of the local interface. Takes an IP address, or the special values
 821           <literal>auto</literal>, <literal>static</literal>, or <literal>dynamic</literal>. When an address
 822           is set, then the local interface must have the address. If <literal>auto</literal>, then one of the
 823           addresses on the local interface is used. Similarly, if <literal>static</literal> or
 824           <literal>dynamic</literal> is set, then one of the static or dynamic addresses on the local
 825           interface is used. Defaults to <literal>auto</literal>.</para>
 826         </listitem>
 827       </varlistentry>
 828       <varlistentry>
 829         <term><varname>EncapsulationType=</varname></term>
 830         <listitem>
 831           <para>Specifies the encapsulation type of the tunnel. Takes one of <literal>udp</literal> or <literal>ip</literal>.</para>
 832         </listitem>
 833       </varlistentry>
 834       <varlistentry>
 835         <term><varname>UDPSourcePort=</varname></term>
 836         <listitem>
 837           <para>Specifies the UDP source port to be used for the tunnel. When UDP encapsulation is selected it's mandotory. Ignored when ip
 838           encapsulation is selected.</para>
 839         </listitem>
 840       </varlistentry>
 841       <varlistentry>
 842         <term><varname>DestinationPort=</varname></term>
 843         <listitem>
 844           <para>Specifies destination port. When UDP encapsulation is selected it's mandotory. Ignored when ip
 845           encapsulation is selected.</para>
 846         </listitem>
 847       </varlistentry>
 848       <varlistentry>
 849         <term><varname>UDPChecksum=</varname></term>
 850         <listitem>
 851           <para>Takes a boolean. When true, specifies if UDP checksum is calculated for transmitted packets over IPv4.</para>
 852         </listitem>
 853       </varlistentry>
 854       <varlistentry>
 855         <term><varname>UDP6ZeroChecksumTx=</varname></term>
 856         <listitem>
 857           <para>Takes a boolean. When true, skip UDP checksum calculation for transmitted packets over IPv6.</para>
 858         </listitem>
 859       </varlistentry>
 860       <varlistentry>
 861         <term><varname>UDP6ZeroChecksumRx=</varname></term>
 862         <listitem>
 863           <para>Takes a boolean. When true, allows incoming UDP packets over IPv6 with zero checksum field.</para>
 864         </listitem>
 865       </varlistentry>
 866     </variablelist>
 867   </refsect1>
 868   <refsect1>
 869     <title>[L2TPSession] Section Options</title>
 870     <para>The <literal>[L2TPSession]</literal> section only applies for
 871     netdevs of kind <literal>l2tp</literal>, and accepts the
 872     following keys:</para>
 873     <variablelist class='network-directives'>
 874       <varlistentry>
 875         <term><varname>Name=</varname></term>
 876         <listitem>
 877           <para>Specifies the name of the session. This option is compulsory.</para>
 878         </listitem>
 879       </varlistentry>
 880       <varlistentry>
 881         <term><varname>SessionId=</varname></term>
 882         <listitem>
 883           <para>Specifies the session id. The value used must match the <literal>SessionId=</literal> value being used at the peer.
 884           Ranges a number between 1 and 4294967295). This option is compulsory.</para>
 885         </listitem>
 886       </varlistentry>
 887       <varlistentry>
 888         <term><varname>PeerSessionId=</varname></term>
 889         <listitem>
 890           <para>Specifies the peer session id. The value used must match the <literal>PeerSessionId=</literal> value being used at the peer.
 891           Ranges a number between 1 and 4294967295). This option is compulsory.</para>
 892         </listitem>
 893       </varlistentry>
 894       <varlistentry>
 895         <term><varname>Layer2SpecificHeader=</varname></term>
 896         <listitem>
 897           <para>Specifies layer2specific header type of the session. One of <literal>none</literal> or <literal>default</literal>. Defaults to <literal>default</literal>.</para>
 898         </listitem>
 899       </varlistentry>
 900     </variablelist>
 901   </refsect1>
 902   <refsect1>
 903     <title>[MACsec] Section Options</title>
 904     <para>The <literal>[MACsec]</literal> section only applies for network devices of kind
 905     <literal>macsec</literal>, and accepts the following keys:</para>
 906
 907     <variablelist class='network-directives'>
 908       <varlistentry>
 909         <term><varname>Port=</varname></term>
 910         <listitem>
 911           <para>Specifies the port to be used for the MACsec transmit channel. The port is used to make
 912           secure channel identifier (SCI). Takes a value between 1 and 65535. Defaults to unset.
 913           </para>
 914         </listitem>
 915       </varlistentry>
 916       <varlistentry>
 917         <term><varname>Encrypt=</varname></term>
 918         <listitem>
 919           <para>Takes a boolean. When true, enable encryption. Defaults to unset.</para>
 920         </listitem>
 921       </varlistentry>
 922     </variablelist>
 923   </refsect1>
 924   <refsect1>
 925     <title>[MACsecReceiveChannel] Section Options</title>
 926     <para>The <literal>[MACsecReceiveChannel]</literal> section only applies for network devices of
 927     kind <literal>macsec</literal>, and accepts the following keys:</para>
 928
 929     <variablelist class='network-directives'>
 930       <varlistentry>
 931         <term><varname>Port=</varname></term>
 932         <listitem>
 933           <para>Specifies the port to be used for the MACsec receive channel. The port is used to make
 934           secure channel identifier (SCI). Takes a value between 1 and 65535. This option is
 935           compulsory, and is not set by default.</para>
 936         </listitem>
 937       </varlistentry>
 938       <varlistentry>
 939         <term><varname>MACAddress=</varname></term>
 940         <listitem>
 941           <para>Specifies the MAC address to be used for the MACsec receive channel. The MAC address
 942           used to make secure channel identifier (SCI). This option is compulsory, and is not set by
 943           default.</para>
 944         </listitem>
 945       </varlistentry>
 946     </variablelist>
 947   </refsect1>
 948   <refsect1>
 949     <title>[MACsecTransmitAssociation] Section Options</title>
 950     <para>The <literal>[MACsecTransmitAssociation]</literal> section only applies for network devices
 951     of kind <literal>macsec</literal>, and accepts the following keys:</para>
 952
 953     <variablelist class='network-directives'>
 954       <varlistentry>
 955         <term><varname>PacketNumber=</varname></term>
 956         <listitem>
 957           <para>Specifies the packet number to be used for replay protection and the construction of
 958           the initialization vector (along with the secure channel identifier [SCI]). Takes a value
 959           between 1-4,294,967,295. Defaults to unset.
 960           </para>
 961         </listitem>
 962       </varlistentry>
 963       <varlistentry>
 964         <term><varname>KeyId=</varname></term>
 965         <listitem>
 966           <para>Specifies the identification for the key. Takes a number between 0-255. This option
 967           is compulsory, and is not set by default.</para>
 968         </listitem>
 969       </varlistentry>
 970       <varlistentry>
 971         <term><varname>Key=</varname></term>
 972         <listitem>
 973           <para>Specifies the encryption key used in the transmission channel. The same key must be
 974           configured on the peer’s matching receive channel. This option is compulsory, and is not set
 975           by default. Takes a 128-bit key encoded in a hexadecimal string, for example
 976           <literal>dffafc8d7b9a43d5b9a3dfbbf6a30c16</literal>.</para>
 977         </listitem>
 978       </varlistentry>
 979       <varlistentry>
 980         <term><varname>KeyFile=</varname></term>
 981         <listitem>
 982           <para>Takes a absolute path to a file which contains a 128-bit key encoded in a hexadecimal
 983           string, which will be used in the transmission channel. When this option is specified,
 984           <varname>Key=</varname> is ignored. Note that the file must be readable by the user
 985           <literal>systemd-network</literal>, so it should be, e.g., owned by
 986           <literal>root:systemd-network</literal> with a <literal>0640</literal> file mode.</para>
 987         </listitem>
 988       </varlistentry>
 989       <varlistentry>
 990         <term><varname>Activate=</varname></term>
 991         <listitem>
 992           <para>Takes a boolean. If enabled, then the security association is activated. Defaults to
 993           unset.</para>
 994         </listitem>
 995       </varlistentry>
 996       <varlistentry>
 997         <term><varname>UseForEncoding=</varname></term>
 998         <listitem>
 999           <para>Takes a boolean. If enabled, then the security association is used for encoding. Only
1000           one <literal>[MACsecTransmitAssociation]</literal> section can enable this option. When enabled,
1001           <varname>Activate=yes</varname> is implied. Defaults to unset.</para>
1002         </listitem>
1003       </varlistentry>
1004     </variablelist>
1005   </refsect1>
1006   <refsect1>
1007     <title>[MACsecReceiveAssociation] Section Options</title>
1008     <para>The <literal>[MACsecReceiveAssociation]</literal> section only applies for
1009     network devices of kind <literal>macsec</literal>, and accepts the
1010     following keys:</para>
1011
1012     <variablelist class='network-directives'>
1013       <varlistentry>
1014         <term><varname>Port=</varname></term>
1015         <listitem>
1016           <para>Accepts the same key in <literal>[MACsecReceiveChannel]</literal> section.</para>
1017         </listitem>
1018       </varlistentry>
1019       <varlistentry>
1020         <term><varname>MACAddress=</varname></term>
1021         <listitem>
1022           <para>Accepts the same key in <literal>[MACsecReceiveChannel]</literal> section.</para>
1023         </listitem>
1024       </varlistentry>
1025       <varlistentry>
1026         <term><varname>PacketNumber=</varname></term>
1027         <listitem>
1028           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1029         </listitem>
1030       </varlistentry>
1031       <varlistentry>
1032         <term><varname>KeyId=</varname></term>
1033         <listitem>
1034           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1035         </listitem>
1036       </varlistentry>
1037       <varlistentry>
1038         <term><varname>Key=</varname></term>
1039         <listitem>
1040           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1041         </listitem>
1042       </varlistentry>
1043       <varlistentry>
1044         <term><varname>KeyFile=</varname></term>
1045         <listitem>
1046           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1047         </listitem>
1048       </varlistentry>
1049       <varlistentry>
1050         <term><varname>Activate=</varname></term>
1051         <listitem>
1052           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1053         </listitem>
1054       </varlistentry>
1055     </variablelist>
1056   </refsect1>
1057   <refsect1>
1058     <title>[Tunnel] Section Options</title>
1059
1060     <para>The <literal>[Tunnel]</literal> section only applies for
1061     netdevs of kind
1062     <literal>ipip</literal>,
1063     <literal>sit</literal>,
1064     <literal>gre</literal>,
1065     <literal>gretap</literal>,
1066     <literal>ip6gre</literal>,
1067     <literal>ip6gretap</literal>,
1068     <literal>vti</literal>,
1069     <literal>vti6</literal>,
1070     <literal>ip6tnl</literal>, and
1071     <literal>erspan</literal> and accepts
1072     the following keys:</para>
1073
1074     <variablelist class='network-directives'>
1075       <varlistentry>
1076         <term><varname>Local=</varname></term>
1077         <listitem>
1078           <para>A static local address for tunneled packets. It must be an address on another interface of
1079           this host, or the special value <literal>any</literal>.</para>
1080         </listitem>
1081       </varlistentry>
1082       <varlistentry>
1083         <term><varname>Remote=</varname></term>
1084         <listitem>
1085           <para>The remote endpoint of the tunnel. Takes an IP address or the special value
1086           <literal>any</literal>.</para>
1087         </listitem>
1088       </varlistentry>
1089       <varlistentry>
1090         <term><varname>TOS=</varname></term>
1091         <listitem>
1092           <para>The Type Of Service byte value for a tunnel interface.
1093           For details about the TOS, see the
1094           <ulink url="http://tools.ietf.org/html/rfc1349"> Type of
1095           Service in the Internet Protocol Suite </ulink> document.
1096           </para>
1097         </listitem>
1098       </varlistentry>
1099       <varlistentry>
1100         <term><varname>TTL=</varname></term>
1101         <listitem>
1102           <para>A fixed Time To Live N on tunneled packets. N is a
1103           number in the range 1–255. 0 is a special value meaning that
1104           packets inherit the TTL value. The default value for IPv4
1105           tunnels is: inherit. The default value for IPv6 tunnels is
1106           64.</para>
1107         </listitem>
1108       </varlistentry>
1109       <varlistentry>
1110         <term><varname>DiscoverPathMTU=</varname></term>
1111         <listitem>
1112           <para>Takes a boolean. When true, enables Path MTU Discovery on
1113           the tunnel.</para>
1114         </listitem>
1115       </varlistentry>
1116       <varlistentry>
1117         <term><varname>IPv6FlowLabel=</varname></term>
1118         <listitem>
1119           <para>Configures the 20-bit flow label (see <ulink url="https://tools.ietf.org/html/rfc6437">
1120           RFC 6437</ulink>) field in the IPv6 header (see <ulink url="https://tools.ietf.org/html/rfc2460">
1121           RFC 2460</ulink>), which is used by a node to label packets of a flow.
1122           It is only used for IPv6 tunnels.
1123           A flow label of zero is used to indicate packets that have
1124           not been labeled.
1125           It can be configured to a value in the range 0–0xFFFFF, or be
1126           set to <literal>inherit</literal>, in which case the original flowlabel is used.</para>
1127         </listitem>
1128       </varlistentry>
1129       <varlistentry>
1130         <term><varname>CopyDSCP=</varname></term>
1131         <listitem>
1132           <para>Takes a boolean. When true, the Differentiated Service Code
1133           Point (DSCP) field will be copied to the inner header from
1134           outer header during the decapsulation of an IPv6 tunnel
1135           packet. DSCP is a field in an IP packet that enables different
1136           levels of service to be assigned to network traffic.
1137           Defaults to <literal>no</literal>.
1138           </para>
1139         </listitem>
1140       </varlistentry>
1141       <varlistentry>
1142         <term><varname>EncapsulationLimit=</varname></term>
1143         <listitem>
1144           <para>The Tunnel Encapsulation Limit option specifies how many additional
1145           levels of encapsulation are permitted to be prepended to the packet.
1146           For example, a Tunnel Encapsulation Limit option containing a limit
1147           value of zero means that a packet carrying that option may not enter
1148           another tunnel before exiting the current tunnel.
1149           (see <ulink url="https://tools.ietf.org/html/rfc2473#section-4.1.1"> RFC 2473</ulink>).
1150           The valid range is 0–255 and <literal>none</literal>. Defaults to 4.
1151         </para>
1152         </listitem>
1153       </varlistentry>
1154       <varlistentry>
1155         <term><varname>Key=</varname></term>
1156         <listitem>
1157           <para>The <varname>Key=</varname> parameter specifies the same key to use in
1158           both directions (<varname>InputKey=</varname> and <varname>OutputKey=</varname>).
1159           The <varname>Key=</varname> is either a number or an IPv4 address-like dotted quad.
1160           It is used as mark-configured SAD/SPD entry as part of the lookup key (both in data
1161           and control path) in ip xfrm (framework used to implement IPsec protocol).
1162           See <ulink url="http://man7.org/linux/man-pages/man8/ip-xfrm.8.html">
1163           ip-xfrm — transform configuration</ulink> for details. It is only used for VTI/VTI6,
1164           GRE, GRETAP, and ERSPAN tunnels.</para>
1165         </listitem>
1166       </varlistentry>
1167       <varlistentry>
1168         <term><varname>InputKey=</varname></term>
1169         <listitem>
1170           <para>The <varname>InputKey=</varname> parameter specifies the key to use for input.
1171           The format is same as <varname>Key=</varname>. It is only used for VTI/VTI6, GRE, GRETAP,
1172           and ERSPAN tunnels.</para>
1173         </listitem>
1174       </varlistentry>
1175       <varlistentry>
1176         <term><varname>OutputKey=</varname></term>
1177         <listitem>
1178           <para>The <varname>OutputKey=</varname> parameter specifies the key to use for output.
1179           The format is same as <varname>Key=</varname>. It is only used for VTI/VTI6, GRE, GRETAP,
1180           and ERSPAN tunnels.</para>
1181         </listitem>
1182       </varlistentry>
1183       <varlistentry>
1184         <term><varname>Mode=</varname></term>
1185         <listitem>
1186           <para>An <literal>ip6tnl</literal> tunnel can be in one of three
1187           modes
1188           <literal>ip6ip6</literal> for IPv6 over IPv6,
1189           <literal>ipip6</literal> for IPv4 over IPv6 or
1190           <literal>any</literal> for either.
1191           </para>
1192         </listitem>
1193       </varlistentry>
1194       <varlistentry>
1195         <term><varname>Independent=</varname></term>
1196         <listitem>
1197           <para>Takes a boolean. When true tunnel does not require .network file. Created as "tunnel@NONE".
1198           Defaults to <literal>false</literal>.
1199           </para>
1200         </listitem>
1201       </varlistentry>
1202       <varlistentry>
1203         <term><varname>AllowLocalRemote=</varname></term>
1204         <listitem>
1205           <para>Takes a boolean. When true allows tunnel traffic on <varname>ip6tnl</varname> devices where the remote endpoint is a local host address.
1206           When unset, the kernel's default will be used.
1207           </para>
1208         </listitem>
1209       </varlistentry>
1210       <varlistentry>
1211         <term><varname>FooOverUDP=</varname></term>
1212         <listitem>
1213           <para>Takes a boolean. Specifies whether <varname>FooOverUDP=</varname> tunnel is to be configured.
1214           Defaults to false. This takes effects only for IPIP, SIT, GRE, and GRETAP tunnels.
1215           For more detail information see
1216           <ulink url="https://lwn.net/Articles/614348">Foo over UDP</ulink></para>
1217         </listitem>
1218       </varlistentry>
1219       <varlistentry>
1220         <term><varname>FOUDestinationPort=</varname></term>
1221         <listitem>
1222           <para>This setting specifies the UDP destination port for encapsulation.
1223           This field is mandatory when <varname>FooOverUDP=yes</varname>, and is not set by default.</para>
1224         </listitem>
1225       </varlistentry>
1226       <varlistentry>
1227         <term><varname>FOUSourcePort=</varname></term>
1228         <listitem>
1229           <para>This setting specifies the UDP source port for encapsulation. Defaults to <constant>0</constant>
1230           — that is, the source port for packets is left to the network stack to decide.</para>
1231         </listitem>
1232       </varlistentry>
1233       <varlistentry>
1234         <term><varname>Encapsulation=</varname></term>
1235         <listitem>
1236           <para>Accepts the same key as in the <literal>[FooOverUDP]</literal> section.</para>
1237         </listitem>
1238       </varlistentry>
1239       <varlistentry>
1240         <term><varname>IPv6RapidDeploymentPrefix=</varname></term>
1241         <listitem>
1242           <para>Reconfigure the tunnel for <ulink url="https://tools.ietf.org/html/rfc5569">IPv6 Rapid
1243           Deployment</ulink>, also known as 6rd. The value is an ISP-specific IPv6 prefix with a non-zero length. Only
1244           applicable to SIT tunnels.</para>
1245         </listitem>
1246       </varlistentry>
1247       <varlistentry>
1248         <term><varname>ISATAP=</varname></term>
1249         <listitem>
1250           <para>Takes a boolean. If set, configures the tunnel as Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) tunnel.
1251           Only applicable to SIT tunnels. When unset, the kernel's default will be used.</para>
1252         </listitem>
1253       </varlistentry>
1254       <varlistentry>
1255         <term><varname>SerializeTunneledPackets=</varname></term>
1256         <listitem>
1257           <para>Takes a boolean. If set to yes, then packets are serialized. Only applies for GRE,
1258           GRETAP, and ERSPAN tunnels. When unset, the kernel's default will be used.
1259           </para>
1260         </listitem>
1261       </varlistentry>
1262       <varlistentry>
1263         <term><varname>ERSPANIndex=</varname></term>
1264         <listitem>
1265           <para>Specifies the ERSPAN index field for the interface, an integer in the range 1-1048575 associated with
1266           the ERSPAN traffic's source port and direction. This field is mandatory.
1267           </para>
1268         </listitem>
1269       </varlistentry>
1270     </variablelist>
1271   </refsect1>
1272
1273   <refsect1>
1274     <title>[FooOverUDP] Section Options</title>
1275
1276     <para>The <literal>[FooOverUDP]</literal> section only applies for
1277     netdevs of kind <literal>fou</literal> and accepts the
1278     following keys:</para>
1279
1280     <variablelist class='network-directives'>
1281       <varlistentry>
1282         <term><varname>Encapsulation=</varname></term>
1283         <listitem>
1284           <para>Specifies the encapsulation mechanism used to store networking packets of various protocols inside the UDP packets. Supports the following values:
1285
1286           <literal>FooOverUDP</literal> provides the simplest no frills model of UDP encapsulation, it simply encapsulates
1287           packets directly in the UDP payload.
1288           <literal>GenericUDPEncapsulation</literal> is a generic and extensible encapsulation, it allows encapsulation of packets for any IP
1289           protocol and optional data as part of the encapsulation.
1290           For more detailed information see <ulink url="https://lwn.net/Articles/615044">Generic UDP Encapsulation</ulink>.
1291           Defaults to <literal>FooOverUDP</literal>.
1292           </para>
1293         </listitem>
1294       </varlistentry>
1295       <varlistentry>
1296         <term><varname>Port=</varname></term>
1297         <listitem>
1298           <para>Specifies the port number, where the IP encapsulation packets will arrive. Please take note that the packets
1299           will arrive with the encapsulation will be removed. Then they will be manually fed back into the network stack, and sent ahead
1300           for delivery to the real destination. This option is mandatory.</para>
1301         </listitem>
1302         </varlistentry>
1303       <varlistentry>
1304         <term><varname>PeerPort=</varname></term>
1305         <listitem>
1306           <para>Specifies the peer port number. Defaults to unset. Note that when peer port is set <literal>Peer=</literal> address is mandotory.</para>
1307         </listitem>
1308         </varlistentry>
1309       <varlistentry>
1310         <term><varname>Protocol=</varname></term>
1311         <listitem>
1312           <para>The <varname>Protocol=</varname> specifies the protocol number of the packets arriving
1313           at the UDP port. When <varname>Encapsulation=FooOverUDP</varname>, this field is mandatory
1314           and is not set by default. Takes an IP protocol name such as <literal>gre</literal> or
1315           <literal>ipip</literal>, or an integer within the range 1-255. When
1316           <varname>Encapsulation=GenericUDPEncapsulation</varname>, this must not be specified.</para>
1317         </listitem>
1318       </varlistentry>
1319       <varlistentry>
1320         <term><varname>Peer=</varname></term>
1321         <listitem>
1322           <para>Configures peer IP address. Note that when peer address is set <literal>PeerPort=</literal> is mandotory.</para>
1323         </listitem>
1324       </varlistentry>
1325       <varlistentry>
1326         <term><varname>Local=</varname></term>
1327         <listitem>
1328           <para>Configures local IP address.</para>
1329         </listitem>
1330       </varlistentry>
1331     </variablelist>
1332   </refsect1>
1333   <refsect1>
1334     <title>[Peer] Section Options</title>
1335
1336       <para>The <literal>[Peer]</literal> section only applies for
1337       netdevs of kind <literal>veth</literal> and accepts the
1338       following keys:</para>
1339
1340       <variablelist class='network-directives'>
1341         <varlistentry>
1342           <term><varname>Name=</varname></term>
1343           <listitem>
1344             <para>The interface name used when creating the netdev.
1345             This option is compulsory.</para>
1346           </listitem>
1347         </varlistentry>
1348         <varlistentry>
1349           <term><varname>MACAddress=</varname></term>
1350           <listitem>
1351             <para>The peer MACAddress, if not set, it is generated in
1352             the same way as the MAC address of the main
1353             interface.</para>
1354           </listitem>
1355         </varlistentry>
1356       </variablelist>
1357   </refsect1>
1358   <refsect1>
1359   <title>[VXCAN] Section Options</title>
1360       <para>The <literal>[VXCAN]</literal> section only applies for
1361       netdevs of kind <literal>vxcan</literal> and accepts the
1362       following key:</para>
1363
1364       <variablelist class='network-directives'>
1365         <varlistentry>
1366           <term><varname>Peer=</varname></term>
1367           <listitem>
1368             <para>The peer interface name used when creating the netdev.
1369             This option is compulsory.</para>
1370           </listitem>
1371         </varlistentry>
1372       </variablelist>
1373   </refsect1>
1374   <refsect1>
1375     <title>[Tun] Section Options</title>
1376
1377     <para>The <literal>[Tun]</literal> section only applies for
1378     netdevs of kind <literal>tun</literal>, and accepts the following
1379     keys:</para>
1380
1381     <variablelist class='network-directives'>
1382       <varlistentry>
1383         <term><varname>OneQueue=</varname></term>
1384         <listitem><para>Takes a boolean. Configures whether
1385         all packets are queued at the device (enabled), or a fixed
1386         number of packets are queued at the device and the rest at the
1387         <literal>qdisc</literal>. Defaults to
1388         <literal>no</literal>.</para>
1389         </listitem>
1390       </varlistentry>
1391       <varlistentry>
1392         <term><varname>MultiQueue=</varname></term>
1393         <listitem><para>Takes a boolean. Configures whether
1394         to use multiple file descriptors (queues) to parallelize
1395         packets sending and receiving. Defaults to
1396         <literal>no</literal>.</para>
1397         </listitem>
1398       </varlistentry>
1399       <varlistentry>
1400         <term><varname>PacketInfo=</varname></term>
1401         <listitem><para>Takes a boolean. Configures whether
1402         packets should be prepended with four extra bytes (two flag
1403         bytes and two protocol bytes). If disabled, it indicates that
1404         the packets will be pure IP packets. Defaults to
1405         <literal>no</literal>.</para>
1406         </listitem>
1407       </varlistentry>
1408       <varlistentry>
1409         <term><varname>VNetHeader=</varname></term>
1410         <listitem><para>Takes a boolean. Configures
1411         IFF_VNET_HDR flag for a tap device. It allows sending
1412         and receiving larger Generic Segmentation Offload (GSO)
1413         packets. This may increase throughput significantly.
1414         Defaults to
1415         <literal>no</literal>.</para>
1416         </listitem>
1417       </varlistentry>
1418       <varlistentry>
1419         <term><varname>User=</varname></term>
1420         <listitem><para>User to grant access to the
1421         <filename>/dev/net/tun</filename> device.</para>
1422         </listitem>
1423       </varlistentry>
1424       <varlistentry>
1425         <term><varname>Group=</varname></term>
1426         <listitem><para>Group to grant access to the
1427         <filename>/dev/net/tun</filename> device.</para>
1428         </listitem>
1429       </varlistentry>
1430
1431     </variablelist>
1432
1433   </refsect1>
1434
1435   <refsect1>
1436     <title>[Tap] Section Options</title>
1437
1438     <para>The <literal>[Tap]</literal> section only applies for
1439     netdevs of kind <literal>tap</literal>, and accepts the same keys
1440     as the <literal>[Tun]</literal> section.</para>
1441   </refsect1>
1442
1443   <refsect1>
1444     <title>[WireGuard] Section Options</title>
1445
1446     <para>The <literal>[WireGuard]</literal> section accepts the following
1447     keys:</para>
1448
1449     <variablelist class='network-directives'>
1450       <varlistentry>
1451         <term><varname>PrivateKey=</varname></term>
1452         <listitem>
1453           <para>The Base64 encoded private key for the interface. It can be
1454             generated using the <command>wg genkey</command> command
1455             (see <citerefentry project="wireguard"><refentrytitle>wg</refentrytitle><manvolnum>8</manvolnum></citerefentry>).
1456             This option or <varname>PrivateKeyFile=</varname> is mandatory to use WireGuard.
1457             Note that because this information is secret, you may want to set
1458             the permissions of the .netdev file to be owned by <literal>root:systemd-network</literal>
1459             with a <literal>0640</literal> file mode.</para>
1460         </listitem>
1461       </varlistentry>
1462       <varlistentry>
1463         <term><varname>PrivateKeyFile=</varname></term>
1464         <listitem>
1465           <para>Takes an absolute path to a file which contains the Base64 encoded private key for the interface.
1466           When this option is specified, then <varname>PrivateKey=</varname> is ignored.
1467           Note that the file must be readable by the user <literal>systemd-network</literal>, so it
1468           should be, e.g., owned by <literal>root:systemd-network</literal> with a
1469           <literal>0640</literal> file mode.</para>
1470         </listitem>
1471       </varlistentry>
1472       <varlistentry>
1473         <term><varname>ListenPort=</varname></term>
1474         <listitem>
1475           <para>Sets UDP port for listening. Takes either value between 1 and 65535
1476             or <literal>auto</literal>. If <literal>auto</literal> is specified,
1477             the port is automatically generated based on interface name.
1478             Defaults to <literal>auto</literal>.</para>
1479         </listitem>
1480       </varlistentry>
1481       <varlistentry>
1482         <term><varname>FirewallMark=</varname></term>
1483         <listitem>
1484           <para>Sets a firewall mark on outgoing WireGuard packets from this interface. Takes a number between 1 and 4294967295.</para>
1485         </listitem>
1486       </varlistentry>
1487     </variablelist>
1488   </refsect1>
1489
1490   <refsect1>
1491     <title>[WireGuardPeer] Section Options</title>
1492
1493     <para>The <literal>[WireGuardPeer]</literal> section accepts the following
1494     keys:</para>
1495
1496     <variablelist class='network-directives'>
1497       <varlistentry>
1498         <term><varname>PublicKey=</varname></term>
1499         <listitem>
1500           <para>Sets a Base64 encoded public key calculated by <command>wg pubkey</command>
1501             (see <citerefentry project="wireguard"><refentrytitle>wg</refentrytitle><manvolnum>8</manvolnum></citerefentry>)
1502             from a private key, and usually transmitted out of band to the
1503             author of the configuration file. This option is mandatory for this
1504             section.</para>
1505         </listitem>
1506       </varlistentry>
1507       <varlistentry>
1508         <term><varname>PresharedKey=</varname></term>
1509         <listitem>
1510           <para>Optional preshared key for the interface. It can be generated
1511             by the <command>wg genpsk</command> command. This option adds an
1512             additional layer of symmetric-key cryptography to be mixed into the
1513             already existing public-key cryptography, for post-quantum
1514             resistance.
1515             Note that because this information is secret, you may want to set
1516             the permissions of the .netdev file to be owned by <literal>root:systemd-networkd</literal>
1517             with a <literal>0640</literal> file mode.</para>
1518         </listitem>
1519       </varlistentry>
1520       <varlistentry>
1521         <term><varname>PresharedKeyFile=</varname></term>
1522         <listitem>
1523           <para>Takes an absolute path to a file which contains the Base64 encoded preshared key for the
1524           peer. When this option is specified, then <varname>PresharedKey=</varname> is ignored.
1525           Note that the file must be readable by the user <literal>systemd-network</literal>, so it
1526           should be, e.g., owned by <literal>root:systemd-network</literal> with a
1527           <literal>0640</literal> file mode.</para>
1528         </listitem>
1529       </varlistentry>
1530       <varlistentry>
1531         <term><varname>AllowedIPs=</varname></term>
1532         <listitem>
1533           <para>Sets a comma-separated list of IP (v4 or v6) addresses with CIDR masks
1534             from which this peer is allowed to send incoming traffic and to
1535             which outgoing traffic for this peer is directed. The catch-all
1536             0.0.0.0/0 may be specified for matching all IPv4 addresses, and
1537             ::/0 may be specified for matching all IPv6 addresses. </para>
1538         </listitem>
1539       </varlistentry>
1540       <varlistentry>
1541         <term><varname>Endpoint=</varname></term>
1542         <listitem>
1543           <para>Sets an endpoint IP address or hostname, followed by a colon, and then
1544             a port number. This endpoint will be updated automatically once to
1545             the most recent source IP address and port of correctly
1546             authenticated packets from the peer at configuration time.</para>
1547         </listitem>
1548       </varlistentry>
1549       <varlistentry>
1550         <term><varname>PersistentKeepalive=</varname></term>
1551         <listitem>
1552           <para>Sets a seconds interval, between 1 and 65535 inclusive, of how often
1553             to send an authenticated empty packet to the peer for the purpose
1554             of keeping a stateful firewall or NAT mapping valid persistently.
1555             For example, if the interface very rarely sends traffic, but it
1556             might at anytime receive traffic from a peer, and it is behind NAT,
1557             the interface might benefit from having a persistent keepalive
1558             interval of 25 seconds. If set to 0 or "off", this option is
1559             disabled. By default or when unspecified, this option is off.
1560             Most users will not need this.</para>
1561         </listitem>
1562       </varlistentry>
1563     </variablelist>
1564   </refsect1>
1565
1566   <refsect1>
1567     <title>[Bond] Section Options</title>
1568
1569     <para>The <literal>[Bond]</literal> section accepts the following
1570     key:</para>
1571
1572     <variablelist class='network-directives'>
1573       <varlistentry>
1574         <term><varname>Mode=</varname></term>
1575         <listitem>
1576           <para>Specifies one of the bonding policies. The default is
1577           <literal>balance-rr</literal> (round robin). Possible values are
1578           <literal>balance-rr</literal>,
1579           <literal>active-backup</literal>,
1580           <literal>balance-xor</literal>,
1581           <literal>broadcast</literal>,
1582           <literal>802.3ad</literal>,
1583           <literal>balance-tlb</literal>, and
1584           <literal>balance-alb</literal>.
1585           </para>
1586         </listitem>
1587       </varlistentry>
1588
1589       <varlistentry>
1590         <term><varname>TransmitHashPolicy=</varname></term>
1591         <listitem>
1592           <para>Selects the transmit hash policy to use for slave
1593           selection in balance-xor, 802.3ad, and tlb modes. Possible
1594           values are
1595           <literal>layer2</literal>,
1596           <literal>layer3+4</literal>,
1597           <literal>layer2+3</literal>,
1598           <literal>encap2+3</literal>, and
1599           <literal>encap3+4</literal>.
1600           </para>
1601         </listitem>
1602       </varlistentry>
1603
1604       <varlistentry>
1605         <term><varname>LACPTransmitRate=</varname></term>
1606         <listitem>
1607           <para>Specifies the rate with which link partner transmits
1608           Link Aggregation Control Protocol Data Unit packets in
1609           802.3ad mode. Possible values are <literal>slow</literal>,
1610           which requests partner to transmit LACPDUs every 30 seconds,
1611           and <literal>fast</literal>, which requests partner to
1612           transmit LACPDUs every second. The default value is
1613           <literal>slow</literal>.</para>
1614         </listitem>
1615       </varlistentry>
1616
1617       <varlistentry>
1618         <term><varname>MIIMonitorSec=</varname></term>
1619         <listitem>
1620           <para>Specifies the frequency that Media Independent
1621           Interface link monitoring will occur. A value of zero
1622           disables MII link monitoring. This value is rounded down to
1623           the nearest millisecond. The default value is 0.</para>
1624         </listitem>
1625       </varlistentry>
1626
1627       <varlistentry>
1628         <term><varname>UpDelaySec=</varname></term>
1629         <listitem>
1630           <para>Specifies the delay before a link is enabled after a
1631           link up status has been detected. This value is rounded down
1632           to a multiple of MIIMonitorSec. The default value is
1633           0.</para>
1634         </listitem>
1635       </varlistentry>
1636
1637       <varlistentry>
1638         <term><varname>DownDelaySec=</varname></term>
1639         <listitem>
1640           <para>Specifies the delay before a link is disabled after a
1641           link down status has been detected. This value is rounded
1642           down to a multiple of MIIMonitorSec. The default value is
1643           0.</para>
1644         </listitem>
1645       </varlistentry>
1646
1647       <varlistentry>
1648         <term><varname>LearnPacketIntervalSec=</varname></term>
1649         <listitem>
1650           <para>Specifies the number of seconds between instances where the bonding
1651           driver sends learning packets to each slave peer switch.
1652           The valid range is 1–0x7fffffff; the default value is 1. This option
1653           has an effect only for the balance-tlb and balance-alb modes.</para>
1654         </listitem>
1655       </varlistentry>
1656
1657       <varlistentry>
1658         <term><varname>AdSelect=</varname></term>
1659         <listitem>
1660           <para>Specifies the 802.3ad aggregation selection logic to use. Possible values are
1661           <literal>stable</literal>,
1662           <literal>bandwidth</literal> and
1663           <literal>count</literal>.
1664           </para>
1665         </listitem>
1666       </varlistentry>
1667
1668       <varlistentry>
1669         <term><varname>AdActorSystemPriority=</varname></term>
1670         <listitem>
1671           <para>Specifies the 802.3ad actor system priority. Ranges [1-65535].</para>
1672         </listitem>
1673       </varlistentry>
1674
1675       <varlistentry>
1676         <term><varname>AdUserPortKey=</varname></term>
1677         <listitem>
1678           <para>Specifies the 802.3ad user defined portion of the port key. Ranges [0-1023].</para>
1679         </listitem>
1680       </varlistentry>
1681
1682       <varlistentry>
1683         <term><varname>AdActorSystem=</varname></term>
1684         <listitem>
1685           <para>Specifies the 802.3ad system mac address. This can not be either NULL or Multicast.</para>
1686         </listitem>
1687       </varlistentry>
1688
1689       <varlistentry>
1690         <term><varname>FailOverMACPolicy=</varname></term>
1691         <listitem>
1692           <para>Specifies whether the active-backup mode should set all slaves to
1693           the same MAC address at the time of enslavement or, when enabled, to perform special handling of the
1694           bond's MAC address in accordance with the selected policy. The default policy is none.
1695           Possible values are
1696           <literal>none</literal>,
1697           <literal>active</literal> and
1698           <literal>follow</literal>.
1699           </para>
1700         </listitem>
1701       </varlistentry>
1702
1703       <varlistentry>
1704         <term><varname>ARPValidate=</varname></term>
1705         <listitem>
1706           <para>Specifies whether or not ARP probes and replies should be
1707           validated in any mode that supports ARP monitoring, or whether
1708           non-ARP traffic should be filtered (disregarded) for link
1709           monitoring purposes. Possible values are
1710           <literal>none</literal>,
1711           <literal>active</literal>,
1712           <literal>backup</literal> and
1713           <literal>all</literal>.
1714           </para>
1715         </listitem>
1716       </varlistentry>
1717
1718       <varlistentry>
1719         <term><varname>ARPIntervalSec=</varname></term>
1720         <listitem>
1721           <para>Specifies the ARP link monitoring frequency in milliseconds.
1722           A value of 0 disables ARP monitoring. The default value is 0.
1723           </para>
1724         </listitem>
1725       </varlistentry>
1726
1727       <varlistentry>
1728         <term><varname>ARPIPTargets=</varname></term>
1729         <listitem>
1730           <para>Specifies the IP addresses to use as ARP monitoring peers when
1731           ARPIntervalSec is greater than 0. These are the targets of the ARP request
1732           sent to determine the health of the link to the targets.
1733           Specify these values in IPv4 dotted decimal format. At least one IP
1734           address must be given for ARP monitoring to function. The
1735           maximum number of targets that can be specified is 16. The
1736           default value is no IP addresses.
1737           </para>
1738         </listitem>
1739       </varlistentry>
1740
1741       <varlistentry>
1742         <term><varname>ARPAllTargets=</varname></term>
1743         <listitem>
1744           <para>Specifies the quantity of ARPIPTargets that must be reachable
1745           in order for the ARP monitor to consider a slave as being up.
1746           This option affects only active-backup mode for slaves with
1747           ARPValidate enabled. Possible values are
1748           <literal>any</literal> and
1749           <literal>all</literal>.
1750           </para>
1751         </listitem>
1752       </varlistentry>
1753
1754       <varlistentry>
1755         <term><varname>PrimaryReselectPolicy=</varname></term>
1756         <listitem>
1757           <para>Specifies the reselection policy for the primary slave.  This
1758           affects how the primary slave is chosen to become the active slave
1759           when failure of the active slave or recovery of the primary slave
1760           occurs. This option is designed to prevent flip-flopping between
1761           the primary slave and other slaves.  Possible values are
1762           <literal>always</literal>,
1763           <literal>better</literal> and
1764           <literal>failure</literal>.
1765           </para>
1766         </listitem>
1767       </varlistentry>
1768
1769       <varlistentry>
1770         <term><varname>ResendIGMP=</varname></term>
1771         <listitem>
1772           <para>Specifies the number of IGMP membership reports to be issued after
1773           a failover event. One membership report is issued immediately after
1774           the failover, subsequent packets are sent in each 200ms interval.
1775           The valid range is 0–255. Defaults to 1. A value of 0
1776           prevents the IGMP membership report from being issued in response
1777           to the failover event.
1778           </para>
1779         </listitem>
1780       </varlistentry>
1781
1782       <varlistentry>
1783         <term><varname>PacketsPerSlave=</varname></term>
1784         <listitem>
1785           <para>Specify the number of packets to transmit through a slave before
1786             moving to the next one. When set to 0, then a slave is chosen at
1787             random. The valid range is 0–65535. Defaults to 1. This option
1788             only has effect when in balance-rr mode.
1789           </para>
1790         </listitem>
1791       </varlistentry>
1792
1793       <varlistentry>
1794         <term><varname>GratuitousARP=</varname></term>
1795         <listitem>
1796           <para>Specify the number of peer notifications (gratuitous ARPs and
1797             unsolicited IPv6 Neighbor Advertisements) to be issued after a
1798             failover event.  As soon as the link is up on the new slave,
1799             a peer notification is sent on the  bonding device and each
1800             VLAN sub-device.  This is repeated at each link monitor interval
1801             (ARPIntervalSec or MIIMonitorSec, whichever is active) if the number is
1802             greater than 1. The valid range is 0–255. The default value is 1.
1803             These options affect only the active-backup mode.
1804           </para>
1805         </listitem>
1806       </varlistentry>
1807
1808       <varlistentry>
1809         <term><varname>AllSlavesActive=</varname></term>
1810         <listitem>
1811           <para>Takes a boolean. Specifies that duplicate frames (received on inactive ports)
1812           should be dropped when false, or delivered when true. Normally, bonding will drop
1813           duplicate frames (received on inactive ports), which is desirable for
1814           most users. But there are some times it is nice to allow duplicate
1815           frames to be delivered. The default value is false (drop duplicate frames
1816           received on inactive ports).
1817           </para>
1818         </listitem>
1819       </varlistentry>
1820
1821       <varlistentry>
1822         <term><varname>DynamicTransmitLoadBalancing=</varname></term>
1823         <listitem>
1824           <para>Takes a boolean. Specifies if dynamic shuffling of flows is enabled. Applies only
1825           for balance-tlb mode. Defaults to unset.
1826           </para>
1827         </listitem>
1828       </varlistentry>
1829
1830       <varlistentry>
1831         <term><varname>MinLinks=</varname></term>
1832         <listitem>
1833           <para>Specifies the minimum number of links that must be active before
1834           asserting carrier. The default value is 0.
1835           </para>
1836         </listitem>
1837       </varlistentry>
1838     </variablelist>
1839
1840     <para>For more detail information see
1841     <ulink url="https://www.kernel.org/doc/Documentation/networking/bonding.txt">
1842     Linux Ethernet Bonding Driver HOWTO</ulink></para>
1843
1844   </refsect1>
1845
1846   <refsect1>
1847     <title>Examples</title>
1848     <example>
1849       <title>/etc/systemd/network/25-bridge.netdev</title>
1850
1851       <programlisting>[NetDev]
1852 Name=bridge0
1853 Kind=bridge</programlisting>
1854     </example>
1855
1856     <example>
1857       <title>/etc/systemd/network/25-vlan1.netdev</title>
1858
1859       <programlisting>[Match]
1860 Virtualization=no
1861
1862 [NetDev]
1863 Name=vlan1
1864 Kind=vlan
1865
1866 [VLAN]
1867 Id=1</programlisting>
1868     </example>
1869     <example>
1870       <title>/etc/systemd/network/25-ipip.netdev</title>
1871       <programlisting>[NetDev]
1872 Name=ipip-tun
1873 Kind=ipip
1874 MTUBytes=1480
1875
1876 [Tunnel]
1877 Local=192.168.223.238
1878 Remote=192.169.224.239
1879 TTL=64</programlisting>
1880     </example>
1881     <example>
1882       <title>/etc/systemd/network/1-fou-tunnel.netdev</title>
1883       <programlisting>[NetDev]
1884 Name=fou-tun
1885 Kind=fou
1886
1887 [FooOverUDP]
1888 Port=5555
1889 Protocol=4
1890       </programlisting>
1891     </example>
1892     <example>
1893       <title>/etc/systemd/network/25-fou-ipip.netdev</title>
1894       <programlisting>[NetDev]
1895 Name=ipip-tun
1896 Kind=ipip
1897
1898 [Tunnel]
1899 Independent=yes
1900 Local=10.65.208.212
1901 Remote=10.65.208.211
1902 FooOverUDP=yes
1903 FOUDestinationPort=5555
1904       </programlisting>
1905     </example>
1906     <example>
1907       <title>/etc/systemd/network/25-tap.netdev</title>
1908       <programlisting>[NetDev]
1909 Name=tap-test
1910 Kind=tap
1911
1912 [Tap]
1913 MultiQueue=yes
1914 PacketInfo=yes</programlisting> </example>
1915
1916     <example>
1917       <title>/etc/systemd/network/25-sit.netdev</title>
1918       <programlisting>[NetDev]
1919 Name=sit-tun
1920 Kind=sit
1921 MTUBytes=1480
1922
1923 [Tunnel]
1924 Local=10.65.223.238
1925 Remote=10.65.223.239</programlisting>
1926     </example>
1927
1928     <example>
1929       <title>/etc/systemd/network/25-6rd.netdev</title>
1930       <programlisting>[NetDev]
1931 Name=6rd-tun
1932 Kind=sit
1933 MTUBytes=1480
1934
1935 [Tunnel]
1936 Local=10.65.223.238
1937 IPv6RapidDeploymentPrefix=2602::/24</programlisting>
1938     </example>
1939
1940     <example>
1941       <title>/etc/systemd/network/25-gre.netdev</title>
1942       <programlisting>[NetDev]
1943 Name=gre-tun
1944 Kind=gre
1945 MTUBytes=1480
1946
1947 [Tunnel]
1948 Local=10.65.223.238
1949 Remote=10.65.223.239</programlisting>
1950     </example>
1951
1952     <example>
1953       <title>/etc/systemd/network/25-vti.netdev</title>
1954
1955       <programlisting>[NetDev]
1956 Name=vti-tun
1957 Kind=vti
1958 MTUBytes=1480
1959
1960 [Tunnel]
1961 Local=10.65.223.238
1962 Remote=10.65.223.239</programlisting>
1963     </example>
1964
1965     <example>
1966       <title>/etc/systemd/network/25-veth.netdev</title>
1967       <programlisting>[NetDev]
1968 Name=veth-test
1969 Kind=veth
1970
1971 [Peer]
1972 Name=veth-peer</programlisting>
1973     </example>
1974
1975     <example>
1976       <title>/etc/systemd/network/25-bond.netdev</title>
1977       <programlisting>[NetDev]
1978 Name=bond1
1979 Kind=bond
1980
1981 [Bond]
1982 Mode=802.3ad
1983 TransmitHashPolicy=layer3+4
1984 MIIMonitorSec=1s
1985 LACPTransmitRate=fast
1986 </programlisting>
1987     </example>
1988
1989     <example>
1990       <title>/etc/systemd/network/25-dummy.netdev</title>
1991       <programlisting>[NetDev]
1992 Name=dummy-test
1993 Kind=dummy
1994 MACAddress=12:34:56:78:9a:bc</programlisting>
1995     </example>
1996     <example>
1997       <title>/etc/systemd/network/25-vrf.netdev</title>
1998       <para>Create a VRF interface with table 42.</para>
1999       <programlisting>[NetDev]
2000 Name=vrf-test
2001 Kind=vrf
2002
2003 [VRF]
2004 Table=42</programlisting>
2005     </example>
2006
2007     <example>
2008       <title>/etc/systemd/network/25-macvtap.netdev</title>
2009       <para>Create a MacVTap device.</para>
2010       <programlisting>[NetDev]
2011 Name=macvtap-test
2012 Kind=macvtap
2013       </programlisting>
2014     </example>
2015     <example>
2016       <title>/etc/systemd/network/25-wireguard.netdev</title>
2017       <programlisting>[NetDev]
2018 Name=wg0
2019 Kind=wireguard
2020
2021 [WireGuard]
2022 PrivateKey=EEGlnEPYJV//kbvvIqxKkQwOiS+UENyPncC4bF46ong=
2023 ListenPort=51820
2024
2025 [WireGuardPeer]
2026 PublicKey=RDf+LSpeEre7YEIKaxg+wbpsNV7du+ktR99uBEtIiCA=
2027 AllowedIPs=fd31:bf08:57cb::/48,192.168.26.0/24
2028 Endpoint=wireguard.example.com:51820</programlisting>
2029     </example>
2030   </refsect1>
2031   <refsect1>
2032     <title>See Also</title>
2033     <para>
2034       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
2035       <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
2036       <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2037       <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2038     </para>
2039   </refsect1>
2040
2041 </refentry>