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