man/systemd.netdev.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refentry id="systemd.netdev" conditional='ENABLE_NETWORKD'>
   7
   8   <refentryinfo>
   9     <title>systemd.network</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>systemd.netdev</refentrytitle>
  15     <manvolnum>5</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>systemd.netdev</refname>
  20     <refpurpose>Virtual Network Device configuration</refpurpose>
  21   </refnamediv>
  22
  23   <refsynopsisdiv>
  24     <para><filename><replaceable>netdev</replaceable>.netdev</filename></para>
  25   </refsynopsisdiv>
  26
  27   <refsect1>
  28     <title>Description</title>
  29
  30     <para>Network setup is performed by
  31     <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  32     </para>
  33
  34     <para>The main Virtual Network Device file must have the extension <filename>.netdev</filename>;
  35     other extensions are ignored. Virtual network devices are created as soon as networkd is
  36     started. If a netdev with the specified name already exists, networkd will use that as-is rather
  37     than create its own. Note that the settings of the pre-existing netdev will not be changed by
  38     networkd.</para>
  39
  40     <para>The <filename>.netdev</filename> files are read from the files located in the system
  41     network directory <filename>/usr/lib/systemd/network</filename>, the volatile runtime network
  42     directory <filename>/run/systemd/network</filename> and the local administration network
  43     directory <filename>/etc/systemd/network</filename>. All configuration files are collectively
  44     sorted and processed in lexical order, regardless of the directories in which they live.
  45     However, files with identical filenames replace each other. Files in <filename>/etc</filename>
  46     have the highest priority, files in <filename>/run</filename> take precedence over files with
  47     the same name in <filename>/usr/lib</filename>. This can be used to override a system-supplied
  48     configuration file with a local file if needed. As a special case, an empty file (file size 0)
  49     or symlink with the same name pointing to <filename>/dev/null</filename> disables the
  50     configuration file entirely (it is "masked").</para>
  51
  52     <para>Along with the netdev file <filename>foo.netdev</filename>, a "drop-in" directory
  53     <filename>foo.netdev.d/</filename> may exist. All files with the suffix <literal>.conf</literal>
  54     from this directory will be parsed after the file itself is parsed. This is useful to alter or
  55     add configuration settings, without having to modify the main configuration file. Each drop-in
  56     file must have appropriate section headers.</para>
  57
  58     <para>In addition to <filename>/etc/systemd/network</filename>, drop-in <literal>.d</literal>
  59     directories can be placed in <filename>/usr/lib/systemd/network</filename> or
  60     <filename>/run/systemd/network</filename> directories. Drop-in files in
  61     <filename>/etc</filename> take precedence over those in <filename>/run</filename> which in turn
  62     take precedence over those in <filename>/usr/lib</filename>. Drop-in files under any of these
  63     directories take precedence over the main netdev file wherever located. (Of course, since
  64     <filename>/run</filename> is temporary and <filename>/usr/lib</filename> is for vendors, it is
  65     unlikely drop-ins should be used in either of those places.)</para>
  66   </refsect1>
  67
  68   <refsect1>
  69     <title>Supported netdev kinds</title>
  70
  71     <para>The following kinds of virtual network devices may be
  72     configured in <filename>.netdev</filename> files:</para>
  73
  74     <table>
  75       <title>Supported kinds of virtual network devices</title>
  76
  77       <tgroup cols='2'>
  78         <colspec colname='kind' />
  79         <colspec colname='explanation' />
  80         <thead><row>
  81           <entry>Kind</entry>
  82           <entry>Description</entry>
  83         </row></thead>
  84         <tbody>
  85           <row><entry><varname>bond</varname></entry>
  86           <entry>A bond device is an aggregation of all its slave devices. See <ulink url="https://www.kernel.org/doc/Documentation/networking/bonding.txt">Linux Ethernet Bonding Driver HOWTO</ulink> for details.Local configuration</entry></row>
  87
  88           <row><entry><varname>bridge</varname></entry>
  89           <entry>A bridge device is a software switch, and each of its slave devices and the bridge itself are ports of the switch.</entry></row>
  90
  91           <row><entry><varname>dummy</varname></entry>
  92           <entry>A dummy device drops all packets sent to it.</entry></row>
  93
  94           <row><entry><varname>gre</varname></entry>
  95           <entry>A Level 3 GRE tunnel over IPv4. See <ulink url="https://tools.ietf.org/html/rfc2784">RFC 2784</ulink> for details.</entry></row>
  96
  97           <row><entry><varname>gretap</varname></entry>
  98           <entry>A Level 2 GRE tunnel over IPv4.</entry></row>
  99
 100           <row><entry><varname>erspan</varname></entry>
 101           <entry>ERSPAN mirrors traffic on one or more source ports and delivers the mirrored traffic to one or more destination ports on another switch. The traffic is encapsulated in generic routing encapsulation (GRE) and is therefore routable across a layer 3 network between the source switch and the destination switch.</entry></row>
 102
 103           <row><entry><varname>ip6gre</varname></entry>
 104           <entry>A Level 3 GRE tunnel over IPv6.</entry></row>
 105
 106           <row><entry><varname>ip6tnl</varname></entry>
 107           <entry>An IPv4 or IPv6 tunnel over IPv6</entry></row>
 108
 109           <row><entry><varname>ip6gretap</varname></entry>
 110           <entry>A Level 2 GRE tunnel over IPv6.</entry></row>
 111
 112           <row><entry><varname>ipip</varname></entry>
 113           <entry>An IPv4 over IPv4 tunnel.</entry></row>
 114
 115           <row><entry><varname>ipvlan</varname></entry>
 116           <entry>An ipvlan device is a stacked device which receives packets from its underlying device based on IP address filtering.</entry></row>
 117
 118           <row><entry><varname>ipvtap</varname></entry>
 119           <entry>An ipvtap device is a stacked device which receives packets from its underlying device based on IP address filtering and can be accessed using the tap user space interface.</entry></row>
 120
 121           <row><entry><varname>macvlan</varname></entry>
 122           <entry>A macvlan device is a stacked device which receives packets from its underlying device based on MAC address filtering.</entry></row>
 123
 124           <row><entry><varname>macvtap</varname></entry>
 125           <entry>A macvtap device is a stacked device which receives packets from its underlying device based on MAC address filtering.</entry></row>
 126
 127           <row><entry><varname>sit</varname></entry>
 128           <entry>An IPv6 over IPv4 tunnel.</entry></row>
 129
 130           <row><entry><varname>tap</varname></entry>
 131           <entry>A persistent Level 2 tunnel between a network device and a device node.</entry></row>
 132
 133           <row><entry><varname>tun</varname></entry>
 134           <entry>A persistent Level 3 tunnel between a network device and a device node.</entry></row>
 135
 136           <row><entry><varname>veth</varname></entry>
 137           <entry>An Ethernet tunnel between a pair of network devices.</entry></row>
 138
 139           <row><entry><varname>vlan</varname></entry>
 140           <entry>A VLAN is a stacked device which receives packets from its underlying device based on VLAN tagging. See <ulink url="http://www.ieee802.org/1/pages/802.1Q.html">IEEE 802.1Q</ulink> for details.</entry></row>
 141
 142           <row><entry><varname>vti</varname></entry>
 143           <entry>An IPv4 over IPSec tunnel.</entry></row>
 144
 145           <row><entry><varname>vti6</varname></entry>
 146           <entry>An IPv6 over IPSec tunnel.</entry></row>
 147
 148           <row><entry><varname>vxlan</varname></entry>
 149           <entry>A virtual extensible LAN (vxlan), for connecting Cloud computing deployments.</entry></row>
 150
 151           <row><entry><varname>geneve</varname></entry>
 152           <entry>A GEneric NEtwork Virtualization Encapsulation (GENEVE) netdev driver.</entry></row>
 153
 154           <row><entry><varname>l2tp</varname></entry>
 155           <entry>A Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs) or as part of the delivery of services by ISPs. It does not provide any encryption or confidentiality by itself</entry></row>
 156
 157           <row><entry><varname>macsec</varname></entry>
 158           <entry>Media Access Control Security (MACsec) is an 802.1AE IEEE industry-standard security technology that provides secure communication for all traffic on Ethernet links. MACsec provides point-to-point security on Ethernet links between directly connected nodes and is capable of identifying and preventing most security threats.</entry></row>
 159
 160           <row><entry><varname>vrf</varname></entry>
 161           <entry>A Virtual Routing and Forwarding (<ulink url="https://www.kernel.org/doc/Documentation/networking/vrf.txt">VRF</ulink>) interface to create separate routing and forwarding domains.</entry></row>
 162
 163           <row><entry><varname>vcan</varname></entry>
 164           <entry>The virtual CAN driver (vcan). Similar to the network loopback devices, vcan offers a virtual local CAN interface.</entry></row>
 165
 166           <row><entry><varname>vxcan</varname></entry>
 167           <entry>The virtual CAN tunnel driver (vxcan). Similar to the virtual ethernet driver veth, vxcan implements a local CAN traffic tunnel between two virtual CAN network devices. When creating a vxcan, two vxcan devices are created as pair. When one end receives the packet it appears on its pair and vice versa. The vxcan can be used for cross namespace communication.
 168           </entry></row>
 169
 170           <row><entry><varname>wireguard</varname></entry>
 171           <entry>WireGuard Secure Network Tunnel.</entry></row>
 172
 173           <row><entry><varname>netdevsim</varname></entry>
 174           <entry>A simulator. This simulated networking device is used for testing various networking APIs and at this time is particularly focused on testing hardware offloading related interfaces.</entry></row>
 175
 176           <row><entry><varname>nlmon</varname></entry>
 177           <entry>A Netlink monitor device. Use an nlmon device when you want to monitor system Netlink messages.</entry></row>
 178
 179           <row><entry><varname>fou</varname></entry>
 180           <entry>Foo-over-UDP tunneling.</entry></row>
 181
 182           <row><entry><varname>xfrm</varname></entry>
 183           <entry>A virtual tunnel interface like vti/vti6 but with several advantages.</entry></row>
 184
 185         </tbody>
 186       </tgroup>
 187     </table>
 188
 189   </refsect1>
 190
 191   <refsect1>
 192     <title>[Match] Section Options</title>
 193
 194     <para>A virtual network device is only created if the
 195     <literal>[Match]</literal> section matches the current
 196     environment, or if the section is empty. The following keys are
 197     accepted:</para>
 198
 199     <variablelist class='network-directives'>
 200       <varlistentry>
 201         <term><varname>Host=</varname></term>
 202         <listitem>
 203           <para>Matches against the hostname or machine ID of the host. See
 204           <literal>ConditionHost=</literal> in
 205           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 206           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 207           If an empty string is assigned, then previously assigned value is cleared.
 208           </para>
 209         </listitem>
 210       </varlistentry>
 211       <varlistentry>
 212         <term><varname>Virtualization=</varname></term>
 213         <listitem>
 214           <para>Checks whether the system is executed in a virtualized environment and optionally test
 215           whether it is a specific implementation. See <literal>ConditionVirtualization=</literal> in
 216           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 217           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 218           If an empty string is assigned, then previously assigned value is cleared.
 219           </para>
 220         </listitem>
 221       </varlistentry>
 222       <varlistentry>
 223         <term><varname>KernelCommandLine=</varname></term>
 224         <listitem>
 225           <para>Checks whether a specific kernel command line option is set. See
 226           <literal>ConditionKernelCommandLine=</literal> in
 227           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 228           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 229           If an empty string is assigned, then previously assigned value is cleared.
 230           </para>
 231         </listitem>
 232       </varlistentry>
 233       <varlistentry>
 234         <term><varname>KernelVersion=</varname></term>
 235         <listitem>
 236           <para>Checks whether the kernel version (as reported by <command>uname -r</command>) matches a
 237           certain expression. See <literal>ConditionKernelVersion=</literal> in
 238           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 239           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 240           If an empty string is assigned, then previously assigned value is cleared.
 241           </para>
 242         </listitem>
 243       </varlistentry>
 244       <varlistentry>
 245         <term><varname>Architecture=</varname></term>
 246         <listitem>
 247           <para>Checks whether the system is running on a specific architecture. See
 248           <literal>ConditionArchitecture=</literal> in
 249           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 250           for details. When prefixed with an exclamation mark (<literal>!</literal>), the result is negated.
 251           If an empty string is assigned, then previously assigned value is cleared.
 252           </para>
 253         </listitem>
 254       </varlistentry>
 255     </variablelist>
 256   </refsect1>
 257
 258   <refsect1>
 259     <title>[NetDev] Section Options</title>
 260
 261     <para>The <literal>[NetDev]</literal> section accepts the
 262     following keys:</para>
 263
 264     <variablelist class='network-directives'>
 265       <varlistentry>
 266         <term><varname>Description=</varname></term>
 267         <listitem>
 268           <para>A free-form description of the netdev.</para>
 269         </listitem>
 270       </varlistentry>
 271       <varlistentry>
 272         <term><varname>Name=</varname></term>
 273         <listitem>
 274           <para>The interface name used when creating the netdev.
 275           This option is compulsory.</para>
 276         </listitem>
 277       </varlistentry>
 278       <varlistentry>
 279         <term><varname>Kind=</varname></term>
 280         <listitem>
 281           <para>The netdev kind. This option is compulsory. See the
 282           <literal>Supported netdev kinds</literal> section for the
 283           valid keys.</para>
 284         </listitem>
 285       </varlistentry>
 286       <varlistentry>
 287         <term><varname>MTUBytes=</varname></term>
 288         <listitem>
 289           <para>The maximum transmission unit in bytes to set for the device. The usual suffixes K, M, G,
 290           are supported and are understood to the base of 1024. For <literal>tun</literal> or
 291           <literal>tap</literal> devices, <varname>MTUBytes=</varname> setting is not currently supported in
 292           <literal>[NetDev]</literal> section. Please specify it in <literal>[Link]</literal> section of
 293           corresponding
 294           <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 295           files.</para>
 296         </listitem>
 297       </varlistentry>
 298       <varlistentry>
 299         <term><varname>MACAddress=</varname></term>
 300         <listitem>
 301           <para>The MAC address to use for the device. For <literal>tun</literal> or <literal>tap</literal>
 302           devices, setting <varname>MACAddress=</varname> in the <literal>[NetDev]</literal> section is not
 303           supported. Please specify it in <literal>[Link]</literal> section of the corresponding
 304           <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 305           file. If this option is not set, <literal>vlan</literal> devices inherit the MAC address of the
 306           physical interface. For other kind of netdevs, if this option is not set, then MAC address is
 307           generated based on the interface name and the
 308           <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 309           </para>
 310         </listitem>
 311       </varlistentry>
 312     </variablelist>
 313   </refsect1>
 314
 315   <refsect1>
 316     <title>[Bridge] Section Options</title>
 317
 318     <para>The <literal>[Bridge]</literal> section only applies for
 319     netdevs of kind <literal>bridge</literal>, and accepts the
 320     following keys:</para>
 321
 322     <variablelist class='network-directives'>
 323       <varlistentry>
 324         <term><varname>HelloTimeSec=</varname></term>
 325         <listitem>
 326           <para>HelloTimeSec specifies the number of seconds between two hello packets
 327           sent out by the root bridge and the designated bridges. Hello packets are
 328           used to communicate information about the topology throughout the entire
 329           bridged local area network.</para>
 330         </listitem>
 331       </varlistentry>
 332       <varlistentry>
 333         <term><varname>MaxAgeSec=</varname></term>
 334         <listitem>
 335           <para>MaxAgeSec specifies the number of seconds of maximum message age.
 336           If the last seen (received) hello packet is more than this number of
 337           seconds old, the bridge in question will start the takeover procedure
 338           in attempt to become the Root Bridge itself.</para>
 339         </listitem>
 340       </varlistentry>
 341       <varlistentry>
 342         <term><varname>ForwardDelaySec=</varname></term>
 343         <listitem>
 344           <para>ForwardDelaySec specifies the number of seconds spent in each
 345           of the Listening and Learning states before the Forwarding state is entered.</para>
 346         </listitem>
 347       </varlistentry>
 348       <varlistentry>
 349         <term><varname>AgeingTimeSec=</varname></term>
 350         <listitem>
 351           <para>This specifies the number of seconds a MAC Address will be kept in
 352           the forwarding database after having a packet received from this MAC Address.</para>
 353         </listitem>
 354       </varlistentry>
 355       <varlistentry>
 356         <term><varname>Priority=</varname></term>
 357         <listitem>
 358           <para>The priority of the bridge. An integer between 0 and 65535. A lower value
 359           means higher priority. The bridge having the lowest priority will be elected as root bridge.</para>
 360         </listitem>
 361       </varlistentry>
 362       <varlistentry>
 363         <term><varname>GroupForwardMask=</varname></term>
 364         <listitem>
 365           <para>A 16-bit bitmask represented as an integer which allows forwarding of link
 366           local frames with 802.1D reserved addresses (01:80:C2:00:00:0X). A logical AND
 367           is performed between the specified bitmask and the exponentiation of 2^X, the
 368           lower nibble of the last octet of the MAC address. For example, a value of 8
 369           would allow forwarding of frames addressed to 01:80:C2:00:00:03 (802.1X PAE).</para>
 370         </listitem>
 371       </varlistentry>
 372       <varlistentry>
 373         <term><varname>DefaultPVID=</varname></term>
 374         <listitem>
 375           <para>This specifies the default port VLAN ID of a newly attached bridge port.
 376           Set this to an integer in the range 1–4094 or <literal>none</literal> to disable the PVID.</para>
 377         </listitem>
 378       </varlistentry>
 379       <varlistentry>
 380         <term><varname>MulticastQuerier=</varname></term>
 381         <listitem>
 382           <para>Takes a boolean. This setting controls the IFLA_BR_MCAST_QUERIER option in the kernel.
 383           If enabled, the kernel will send general ICMP queries from a zero source address.
 384           This feature should allow faster convergence on startup, but it causes some
 385           multicast-aware switches to misbehave and disrupt forwarding of multicast packets.
 386           When unset, the kernel's default will be used.
 387           </para>
 388         </listitem>
 389       </varlistentry>
 390       <varlistentry>
 391         <term><varname>MulticastSnooping=</varname></term>
 392         <listitem>
 393           <para>Takes a boolean. This setting controls the IFLA_BR_MCAST_SNOOPING option in the kernel.
 394           If enabled, IGMP snooping monitors the Internet Group Management Protocol (IGMP) traffic
 395           between hosts and multicast routers. When unset, the kernel's default will be used.
 396           </para>
 397         </listitem>
 398       </varlistentry>
 399       <varlistentry>
 400         <term><varname>VLANFiltering=</varname></term>
 401         <listitem>
 402           <para>Takes a boolean. This setting controls the IFLA_BR_VLAN_FILTERING option in the kernel.
 403           If enabled, the bridge will be started in VLAN-filtering mode. When unset, the kernel's default will be used.
 404           </para>
 405         </listitem>
 406       </varlistentry>
 407       <varlistentry>
 408         <term><varname>STP=</varname></term>
 409         <listitem>
 410           <para>Takes a boolean. This enables the bridge's Spanning Tree Protocol (STP).
 411           When unset, the kernel's default will be used.
 412           </para>
 413         </listitem>
 414       </varlistentry>
 415     </variablelist>
 416   </refsect1>
 417
 418   <refsect1>
 419     <title>[VLAN] Section Options</title>
 420
 421     <para>The <literal>[VLAN]</literal> section only applies for
 422     netdevs of kind <literal>vlan</literal>, and accepts the
 423     following key:</para>
 424
 425     <variablelist class='network-directives'>
 426       <varlistentry>
 427         <term><varname>Id=</varname></term>
 428         <listitem>
 429           <para>The VLAN ID to use. An integer in the range 0–4094.
 430           This option is compulsory.</para>
 431         </listitem>
 432       </varlistentry>
 433       <varlistentry>
 434         <term><varname>GVRP=</varname></term>
 435         <listitem>
 436           <para>Takes a boolean. The Generic VLAN Registration Protocol (GVRP) is a protocol that
 437           allows automatic learning of VLANs on a network.
 438           When unset, the kernel's default will be used.
 439           </para>
 440         </listitem>
 441       </varlistentry>
 442       <varlistentry>
 443         <term><varname>MVRP=</varname></term>
 444         <listitem>
 445           <para>Takes a boolean. Multiple VLAN Registration Protocol (MVRP) formerly known as GARP VLAN
 446           Registration Protocol (GVRP) is a standards-based Layer 2 network protocol,
 447           for automatic configuration of VLAN information on switches. It was defined
 448           in the 802.1ak amendment to 802.1Q-2005. When unset, the kernel's default will be used.
 449           </para>
 450         </listitem>
 451       </varlistentry>
 452       <varlistentry>
 453         <term><varname>LooseBinding=</varname></term>
 454         <listitem>
 455           <para>Takes a boolean. The VLAN loose binding mode, in which only the operational state is passed
 456           from the parent to the associated VLANs, but the VLAN device state is not changed.
 457           When unset, the kernel's default will be used.</para>
 458         </listitem>
 459       </varlistentry>
 460       <varlistentry>
 461         <term><varname>ReorderHeader=</varname></term>
 462         <listitem>
 463           <para>Takes a boolean. The VLAN reorder header is set VLAN interfaces behave like physical interfaces.
 464           When unset, the kernel's default will be used.</para>
 465         </listitem>
 466       </varlistentry>
 467     </variablelist>
 468   </refsect1>
 469
 470   <refsect1>
 471     <title>[MACVLAN] Section Options</title>
 472
 473     <para>The <literal>[MACVLAN]</literal> section only applies for
 474     netdevs of kind <literal>macvlan</literal>, and accepts the
 475     following key:</para>
 476
 477     <variablelist class='network-directives'>
 478       <varlistentry>
 479         <term><varname>Mode=</varname></term>
 480         <listitem>
 481           <para>The MACVLAN mode to use. The supported options are
 482           <literal>private</literal>,
 483           <literal>vepa</literal>,
 484           <literal>bridge</literal>, and
 485           <literal>passthru</literal>.
 486           </para>
 487         </listitem>
 488       </varlistentry>
 489     </variablelist>
 490   </refsect1>
 491
 492   <refsect1>
 493     <title>[MACVTAP] Section Options</title>
 494
 495     <para>The <literal>[MACVTAP]</literal> section applies for
 496     netdevs of kind <literal>macvtap</literal> and accepts the
 497     same key as <literal>[MACVLAN]</literal>.</para>
 498   </refsect1>
 499
 500   <refsect1>
 501     <title>[IPVLAN] Section Options</title>
 502
 503     <para>The <literal>[IPVLAN]</literal> section only applies for
 504     netdevs of kind <literal>ipvlan</literal>, and accepts the
 505     following key:</para>
 506
 507     <variablelist class='network-directives'>
 508       <varlistentry>
 509         <term><varname>Mode=</varname></term>
 510         <listitem>
 511           <para>The IPVLAN mode to use. The supported options are
 512           <literal>L2</literal>,<literal>L3</literal> and <literal>L3S</literal>.
 513           </para>
 514         </listitem>
 515       </varlistentry>
 516       <varlistentry>
 517         <term><varname>Flags=</varname></term>
 518         <listitem>
 519           <para>The IPVLAN flags to use. The supported options are
 520           <literal>bridge</literal>,<literal>private</literal> and <literal>vepa</literal>.
 521           </para>
 522         </listitem>
 523       </varlistentry>
 524     </variablelist>
 525   </refsect1>
 526
 527   <refsect1>
 528     <title>[IPVTAP] Section Options</title>
 529
 530     <para>The <literal>[IPVTAP]</literal> section only applies for
 531     netdevs of kind <literal>ipvtap</literal> and accepts the
 532     same key as <literal>[IPVLAN]</literal>.</para>
 533   </refsect1>
 534
 535   <refsect1>
 536     <title>[VXLAN] Section Options</title>
 537
 538     <para>The <literal>[VXLAN]</literal> section only applies for
 539     netdevs of kind <literal>vxlan</literal>, and accepts the
 540     following keys:</para>
 541
 542     <variablelist class='network-directives'>
 543       <varlistentry>
 544         <term><varname>VNI=</varname></term>
 545         <listitem>
 546           <para>The VXLAN Network Identifier (or VXLAN Segment ID). Takes a number in the range 1-16777215.</para>
 547         </listitem>
 548       </varlistentry>
 549       <varlistentry>
 550         <term><varname>Remote=</varname></term>
 551         <listitem>
 552           <para>Configures destination IP address.</para>
 553         </listitem>
 554       </varlistentry>
 555       <varlistentry>
 556         <term><varname>Local=</varname></term>
 557         <listitem>
 558           <para>Configures local IP address.</para>
 559         </listitem>
 560       </varlistentry>
 561       <varlistentry>
 562         <term><varname>Group=</varname></term>
 563         <listitem>
 564           <para>Configures VXLAN multicast group IP address. All members of a VXLAN must use the same multicast group address.</para>
 565         </listitem>
 566       </varlistentry>
 567       <varlistentry>
 568         <term><varname>TOS=</varname></term>
 569         <listitem>
 570           <para>The Type Of Service byte value for a vxlan interface.</para>
 571         </listitem>
 572       </varlistentry>
 573       <varlistentry>
 574         <term><varname>TTL=</varname></term>
 575         <listitem>
 576           <para>A fixed Time To Live N on Virtual eXtensible Local Area Network packets.
 577           Takes <literal>inherit</literal> or a number in the range 0–255. 0 is a special
 578           value meaning inherit the inner protocol's TTL value. <literal>inherit</literal>
 579           means that it will inherit the outer protocol's TTL value.</para>
 580         </listitem>
 581       </varlistentry>
 582       <varlistentry>
 583         <term><varname>MacLearning=</varname></term>
 584         <listitem>
 585           <para>Takes a boolean. When true, enables dynamic MAC learning
 586           to discover remote MAC addresses.</para>
 587         </listitem>
 588       </varlistentry>
 589       <varlistentry>
 590         <term><varname>FDBAgeingSec=</varname></term>
 591         <listitem>
 592           <para>The lifetime of Forwarding Database entry learnt by
 593           the kernel, in seconds.</para>
 594         </listitem>
 595       </varlistentry>
 596       <varlistentry>
 597         <term><varname>MaximumFDBEntries=</varname></term>
 598         <listitem>
 599           <para>Configures maximum number of FDB entries.</para>
 600         </listitem>
 601       </varlistentry>
 602       <varlistentry>
 603         <term><varname>ReduceARPProxy=</varname></term>
 604         <listitem>
 605           <para>Takes a boolean. When true, bridge-connected VXLAN tunnel
 606           endpoint answers ARP requests from the local bridge on behalf
 607           of remote Distributed Overlay Virtual Ethernet
 608           <ulink url="https://en.wikipedia.org/wiki/Distributed_Overlay_Virtual_Ethernet">
 609           (DVOE)</ulink> clients. Defaults to false.</para>
 610         </listitem>
 611       </varlistentry>
 612       <varlistentry>
 613         <term><varname>L2MissNotification=</varname></term>
 614         <listitem>
 615           <para>Takes a boolean. When true, enables netlink LLADDR miss
 616           notifications.</para>
 617         </listitem>
 618       </varlistentry>
 619       <varlistentry>
 620         <term><varname>L3MissNotification=</varname></term>
 621         <listitem>
 622           <para>Takes a boolean. When true, enables netlink IP address miss
 623           notifications.</para>
 624         </listitem>
 625       </varlistentry>
 626       <varlistentry>
 627         <term><varname>RouteShortCircuit=</varname></term>
 628         <listitem>
 629           <para>Takes a boolean. When true, route short circuiting is turned
 630           on.</para>
 631         </listitem>
 632       </varlistentry>
 633       <varlistentry>
 634         <term><varname>UDPChecksum=</varname></term>
 635         <listitem>
 636           <para>Takes a boolean. When true, transmitting UDP checksums when doing VXLAN/IPv4 is turned on.</para>
 637         </listitem>
 638       </varlistentry>
 639       <varlistentry>
 640         <term><varname>UDP6ZeroChecksumTx=</varname></term>
 641         <listitem>
 642           <para>Takes a boolean. When true, sending zero checksums in VXLAN/IPv6 is turned on.</para>
 643         </listitem>
 644       </varlistentry>
 645       <varlistentry>
 646         <term><varname>UDP6ZeroChecksumRx=</varname></term>
 647         <listitem>
 648           <para>Takes a boolean. When true, receiving zero checksums in VXLAN/IPv6 is turned on.</para>
 649         </listitem>
 650       </varlistentry>
 651       <varlistentry>
 652         <term><varname>RemoteChecksumTx=</varname></term>
 653         <listitem>
 654           <para>Takes a boolean. When true, remote transmit checksum offload of VXLAN is turned on.</para>
 655         </listitem>
 656       </varlistentry>
 657       <varlistentry>
 658         <term><varname>RemoteChecksumRx=</varname></term>
 659         <listitem>
 660           <para>Takes a boolean. When true, remote receive checksum offload in VXLAN is turned on.</para>
 661         </listitem>
 662       </varlistentry>
 663       <varlistentry>
 664         <term><varname>GroupPolicyExtension=</varname></term>
 665         <listitem>
 666           <para>Takes a boolean. When true, it enables Group Policy VXLAN extension security label mechanism
 667           across network peers based on VXLAN. For details about the Group Policy VXLAN, see the
 668           <ulink url="https://tools.ietf.org/html/draft-smith-vxlan-group-policy">
 669           VXLAN Group Policy </ulink> document. Defaults to false.</para>
 670         </listitem>
 671       </varlistentry>
 672       <varlistentry>
 673         <term><varname>GenericProtocolExtension=</varname></term>
 674         <listitem>
 675           <para>Takes a boolean. When true, Generic Protocol Extension extends the existing VXLAN protocol
 676           to provide protocol typing, OAM, and versioning capabilities. For details about the VXLAN GPE
 677           Header, see the <ulink url="https://tools.ietf.org/html/draft-ietf-nvo3-vxlan-gpe-07">
 678           Generic Protocol Extension for VXLAN </ulink> document. If destination port is not specified and
 679           Generic Protocol Extension is set then default port of 4790 is used. Defaults to false.</para>
 680         </listitem>
 681       </varlistentry>
 682       <varlistentry>
 683         <term><varname>DestinationPort=</varname></term>
 684         <listitem>
 685           <para>Configures the default destination UDP port on a per-device basis.
 686           If destination port is not specified then Linux kernel default will be used.
 687           Set destination port 4789 to get the IANA assigned value. If not set or if the
 688           destination port is assigned the empty string the default port of 4789 is used.</para>
 689         </listitem>
 690       </varlistentry>
 691       <varlistentry>
 692         <term><varname>PortRange=</varname></term>
 693         <listitem>
 694           <para>Configures VXLAN port range. VXLAN bases source
 695           UDP port based on flow to help the receiver to be able
 696           to load balance based on outer header flow. It
 697           restricts the port range to the normal UDP local
 698           ports, and allows overriding via configuration.</para>
 699         </listitem>
 700       </varlistentry>
 701       <varlistentry>
 702         <term><varname>FlowLabel=</varname></term>
 703         <listitem>
 704           <para>Specifies the flow label to use in outgoing packets.
 705           The valid range is 0-1048575.
 706           </para>
 707         </listitem>
 708       </varlistentry>
 709       <varlistentry>
 710         <term><varname>IPDoNotFragment=</varname></term>
 711         <listitem>
 712           <para>Allows to set the IPv4 Do not Fragment (DF) bit in outgoing packets, or to inherit its
 713           value from the IPv4 inner header. Takes a boolean value, or <literal>inherit</literal>. Set
 714           to <literal>inherit</literal> if the encapsulated protocol is IPv6. When unset, the kernel's
 715           default will be used.</para>
 716         </listitem>
 717       </varlistentry>
 718     </variablelist>
 719   </refsect1>
 720
 721   <refsect1>
 722     <title>[GENEVE] Section Options</title>
 723
 724     <para>The <literal>[GENEVE]</literal> section only applies for
 725     netdevs of kind <literal>geneve</literal>, and accepts the
 726     following keys:</para>
 727
 728     <variablelist class='network-directives'>
 729       <varlistentry>
 730         <term><varname>Id=</varname></term>
 731         <listitem>
 732           <para>Specifies the Virtual Network Identifier (VNI) to use. Ranges [0-16777215]. This field is mandatory.</para>
 733         </listitem>
 734       </varlistentry>
 735       <varlistentry>
 736         <term><varname>Remote=</varname></term>
 737         <listitem>
 738           <para>Specifies the unicast destination IP address to use in outgoing packets.</para>
 739         </listitem>
 740       </varlistentry>
 741       <varlistentry>
 742         <term><varname>TOS=</varname></term>
 743         <listitem>
 744           <para>Specifies the TOS value to use in outgoing packets. Ranges [1-255].</para>
 745         </listitem>
 746       </varlistentry>
 747       <varlistentry>
 748         <term><varname>TTL=</varname></term>
 749         <listitem>
 750           <para>Accepts the same key in <literal>[VXLAN]</literal> section except when unset or
 751           set to 0, the kernel's default will be used meaning that packets TTL will be set from
 752           <filename>/proc/sys/net/ipv4/ip_default_ttl</filename>.</para>
 753         </listitem>
 754       </varlistentry>
 755       <varlistentry>
 756         <term><varname>UDPChecksum=</varname></term>
 757         <listitem>
 758           <para>Takes a boolean. When true, specifies if UDP checksum is calculated for transmitted packets over IPv4.</para>
 759         </listitem>
 760       </varlistentry>
 761       <varlistentry>
 762         <term><varname>UDP6ZeroChecksumTx=</varname></term>
 763         <listitem>
 764           <para>Takes a boolean. When true, skip UDP checksum calculation for transmitted packets over IPv6.</para>
 765         </listitem>
 766       </varlistentry>
 767       <varlistentry>
 768         <term><varname>UDP6ZeroChecksumRx=</varname></term>
 769         <listitem>
 770           <para>Takes a boolean. When true, allows incoming UDP packets over IPv6 with zero checksum field.</para>
 771         </listitem>
 772       </varlistentry>
 773       <varlistentry>
 774         <term><varname>DestinationPort=</varname></term>
 775         <listitem>
 776           <para>Specifies destination port. Defaults to 6081. If not set or assigned the empty string, the default
 777           port of 6081 is used.</para>
 778         </listitem>
 779       </varlistentry>
 780       <varlistentry>
 781         <term><varname>FlowLabel=</varname></term>
 782         <listitem>
 783           <para>Specifies the flow label to use in outgoing packets.</para>
 784         </listitem>
 785       </varlistentry>
 786       <varlistentry>
 787         <term><varname>IPDoNotFragment=</varname></term>
 788         <listitem>
 789           <para>Accepts the same key in <literal>[VXLAN]</literal> section.</para>
 790         </listitem>
 791       </varlistentry>
 792     </variablelist>
 793   </refsect1>
 794
 795   <refsect1>
 796     <title>[L2TP] Section Options</title>
 797
 798     <para>The <literal>[L2TP]</literal> section only applies for
 799     netdevs of kind <literal>l2tp</literal>, and accepts the
 800     following keys:</para>
 801
 802     <variablelist class='network-directives'>
 803       <varlistentry>
 804         <term><varname>TunnelId=</varname></term>
 805         <listitem>
 806           <para>Specifies the tunnel id. The value used must match the <literal>PeerTunnelId=</literal> value being used at the peer.
 807           Ranges a number between 1 and 4294967295). This option is compulsory.</para>
 808         </listitem>
 809       </varlistentry>
 810       <varlistentry>
 811         <term><varname>PeerTunnelId=</varname></term>
 812         <listitem>
 813           <para>Specifies the peer tunnel id. The value used must match the <literal>PeerTunnelId=</literal> value being used at the peer.
 814           Ranges a number between 1 and 4294967295). This option is compulsory.</para>
 815         </listitem>
 816       </varlistentry>
 817       <varlistentry>
 818         <term><varname>Remote=</varname></term>
 819         <listitem>
 820           <para>Specifies the IP address of the remote peer. This option is compulsory.</para>
 821         </listitem>
 822       </varlistentry>
 823       <varlistentry>
 824         <term><varname>Local=</varname></term>
 825         <listitem>
 826           <para>Specifies the IP address of the local interface. Takes an IP address, or the special values
 827           <literal>auto</literal>, <literal>static</literal>, or <literal>dynamic</literal>. When an address
 828           is set, then the local interface must have the address. If <literal>auto</literal>, then one of the
 829           addresses on the local interface is used. Similarly, if <literal>static</literal> or
 830           <literal>dynamic</literal> is set, then one of the static or dynamic addresses on the local
 831           interface is used. Defaults to <literal>auto</literal>.</para>
 832         </listitem>
 833       </varlistentry>
 834       <varlistentry>
 835         <term><varname>EncapsulationType=</varname></term>
 836         <listitem>
 837           <para>Specifies the encapsulation type of the tunnel. Takes one of <literal>udp</literal> or <literal>ip</literal>.</para>
 838         </listitem>
 839       </varlistentry>
 840       <varlistentry>
 841         <term><varname>UDPSourcePort=</varname></term>
 842         <listitem>
 843           <para>Specifies the UDP source port to be used for the tunnel. When UDP encapsulation is selected it's mandotory. Ignored when ip
 844           encapsulation is selected.</para>
 845         </listitem>
 846       </varlistentry>
 847       <varlistentry>
 848         <term><varname>DestinationPort=</varname></term>
 849         <listitem>
 850           <para>Specifies destination port. When UDP encapsulation is selected it's mandotory. Ignored when ip
 851           encapsulation is selected.</para>
 852         </listitem>
 853       </varlistentry>
 854       <varlistentry>
 855         <term><varname>UDPChecksum=</varname></term>
 856         <listitem>
 857           <para>Takes a boolean. When true, specifies if UDP checksum is calculated for transmitted packets over IPv4.</para>
 858         </listitem>
 859       </varlistentry>
 860       <varlistentry>
 861         <term><varname>UDP6ZeroChecksumTx=</varname></term>
 862         <listitem>
 863           <para>Takes a boolean. When true, skip UDP checksum calculation for transmitted packets over IPv6.</para>
 864         </listitem>
 865       </varlistentry>
 866       <varlistentry>
 867         <term><varname>UDP6ZeroChecksumRx=</varname></term>
 868         <listitem>
 869           <para>Takes a boolean. When true, allows incoming UDP packets over IPv6 with zero checksum field.</para>
 870         </listitem>
 871       </varlistentry>
 872     </variablelist>
 873   </refsect1>
 874
 875   <refsect1>
 876     <title>[L2TPSession] Section Options</title>
 877
 878     <para>The <literal>[L2TPSession]</literal> section only applies for
 879     netdevs of kind <literal>l2tp</literal>, and accepts the
 880     following keys:</para>
 881     <variablelist class='network-directives'>
 882       <varlistentry>
 883         <term><varname>Name=</varname></term>
 884         <listitem>
 885           <para>Specifies the name of the session. This option is compulsory.</para>
 886         </listitem>
 887       </varlistentry>
 888       <varlistentry>
 889         <term><varname>SessionId=</varname></term>
 890         <listitem>
 891           <para>Specifies the session id. The value used must match the <literal>SessionId=</literal> value being used at the peer.
 892           Ranges a number between 1 and 4294967295). This option is compulsory.</para>
 893         </listitem>
 894       </varlistentry>
 895       <varlistentry>
 896         <term><varname>PeerSessionId=</varname></term>
 897         <listitem>
 898           <para>Specifies the peer session id. The value used must match the <literal>PeerSessionId=</literal> value being used at the peer.
 899           Ranges a number between 1 and 4294967295). This option is compulsory.</para>
 900         </listitem>
 901       </varlistentry>
 902       <varlistentry>
 903         <term><varname>Layer2SpecificHeader=</varname></term>
 904         <listitem>
 905           <para>Specifies layer2specific header type of the session. One of <literal>none</literal> or <literal>default</literal>. Defaults to <literal>default</literal>.</para>
 906         </listitem>
 907       </varlistentry>
 908     </variablelist>
 909   </refsect1>
 910
 911   <refsect1>
 912     <title>[MACsec] Section Options</title>
 913
 914     <para>The <literal>[MACsec]</literal> section only applies for network devices of kind
 915     <literal>macsec</literal>, and accepts the following keys:</para>
 916
 917     <variablelist class='network-directives'>
 918       <varlistentry>
 919         <term><varname>Port=</varname></term>
 920         <listitem>
 921           <para>Specifies the port to be used for the MACsec transmit channel. The port is used to make
 922           secure channel identifier (SCI). Takes a value between 1 and 65535. Defaults to unset.
 923           </para>
 924         </listitem>
 925       </varlistentry>
 926       <varlistentry>
 927         <term><varname>Encrypt=</varname></term>
 928         <listitem>
 929           <para>Takes a boolean. When true, enable encryption. Defaults to unset.</para>
 930         </listitem>
 931       </varlistentry>
 932     </variablelist>
 933   </refsect1>
 934
 935   <refsect1>
 936     <title>[MACsecReceiveChannel] Section Options</title>
 937     <para>The <literal>[MACsecReceiveChannel]</literal> section only applies for network devices of
 938     kind <literal>macsec</literal>, and accepts the following keys:</para>
 939
 940     <variablelist class='network-directives'>
 941       <varlistentry>
 942         <term><varname>Port=</varname></term>
 943         <listitem>
 944           <para>Specifies the port to be used for the MACsec receive channel. The port is used to make
 945           secure channel identifier (SCI). Takes a value between 1 and 65535. This option is
 946           compulsory, and is not set by default.</para>
 947         </listitem>
 948       </varlistentry>
 949       <varlistentry>
 950         <term><varname>MACAddress=</varname></term>
 951         <listitem>
 952           <para>Specifies the MAC address to be used for the MACsec receive channel. The MAC address
 953           used to make secure channel identifier (SCI). This option is compulsory, and is not set by
 954           default.</para>
 955         </listitem>
 956       </varlistentry>
 957     </variablelist>
 958   </refsect1>
 959
 960   <refsect1>
 961     <title>[MACsecTransmitAssociation] Section Options</title>
 962
 963     <para>The <literal>[MACsecTransmitAssociation]</literal> section only applies for network devices
 964     of kind <literal>macsec</literal>, and accepts the following keys:</para>
 965
 966     <variablelist class='network-directives'>
 967       <varlistentry>
 968         <term><varname>PacketNumber=</varname></term>
 969         <listitem>
 970           <para>Specifies the packet number to be used for replay protection and the construction of
 971           the initialization vector (along with the secure channel identifier [SCI]). Takes a value
 972           between 1-4,294,967,295. Defaults to unset.
 973           </para>
 974         </listitem>
 975       </varlistentry>
 976       <varlistentry>
 977         <term><varname>KeyId=</varname></term>
 978         <listitem>
 979           <para>Specifies the identification for the key. Takes a number between 0-255. This option
 980           is compulsory, and is not set by default.</para>
 981         </listitem>
 982       </varlistentry>
 983       <varlistentry>
 984         <term><varname>Key=</varname></term>
 985         <listitem>
 986           <para>Specifies the encryption key used in the transmission channel. The same key must be
 987           configured on the peer’s matching receive channel. This option is compulsory, and is not set
 988           by default. Takes a 128-bit key encoded in a hexadecimal string, for example
 989           <literal>dffafc8d7b9a43d5b9a3dfbbf6a30c16</literal>.</para>
 990         </listitem>
 991       </varlistentry>
 992       <varlistentry>
 993         <term><varname>KeyFile=</varname></term>
 994         <listitem>
 995           <para>Takes a absolute path to a file which contains a 128-bit key encoded in a hexadecimal
 996           string, which will be used in the transmission channel. When this option is specified,
 997           <varname>Key=</varname> is ignored. Note that the file must be readable by the user
 998           <literal>systemd-network</literal>, so it should be, e.g., owned by
 999           <literal>root:systemd-network</literal> with a <literal>0640</literal> file mode.</para>
1000         </listitem>
1001       </varlistentry>
1002       <varlistentry>
1003         <term><varname>Activate=</varname></term>
1004         <listitem>
1005           <para>Takes a boolean. If enabled, then the security association is activated. Defaults to
1006           unset.</para>
1007         </listitem>
1008       </varlistentry>
1009       <varlistentry>
1010         <term><varname>UseForEncoding=</varname></term>
1011         <listitem>
1012           <para>Takes a boolean. If enabled, then the security association is used for encoding. Only
1013           one <literal>[MACsecTransmitAssociation]</literal> section can enable this option. When enabled,
1014           <varname>Activate=yes</varname> is implied. Defaults to unset.</para>
1015         </listitem>
1016       </varlistentry>
1017     </variablelist>
1018   </refsect1>
1019
1020   <refsect1>
1021     <title>[MACsecReceiveAssociation] Section Options</title>
1022
1023     <para>The <literal>[MACsecReceiveAssociation]</literal> section only applies for
1024     network devices of kind <literal>macsec</literal>, and accepts the
1025     following keys:</para>
1026
1027     <variablelist class='network-directives'>
1028       <varlistentry>
1029         <term><varname>Port=</varname></term>
1030         <listitem>
1031           <para>Accepts the same key in <literal>[MACsecReceiveChannel]</literal> section.</para>
1032         </listitem>
1033       </varlistentry>
1034       <varlistentry>
1035         <term><varname>MACAddress=</varname></term>
1036         <listitem>
1037           <para>Accepts the same key in <literal>[MACsecReceiveChannel]</literal> section.</para>
1038         </listitem>
1039       </varlistentry>
1040       <varlistentry>
1041         <term><varname>PacketNumber=</varname></term>
1042         <listitem>
1043           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1044         </listitem>
1045       </varlistentry>
1046       <varlistentry>
1047         <term><varname>KeyId=</varname></term>
1048         <listitem>
1049           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1050         </listitem>
1051       </varlistentry>
1052       <varlistentry>
1053         <term><varname>Key=</varname></term>
1054         <listitem>
1055           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1056         </listitem>
1057       </varlistentry>
1058       <varlistentry>
1059         <term><varname>KeyFile=</varname></term>
1060         <listitem>
1061           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1062         </listitem>
1063       </varlistentry>
1064       <varlistentry>
1065         <term><varname>Activate=</varname></term>
1066         <listitem>
1067           <para>Accepts the same key in <literal>[MACsecTransmitAssociation]</literal> section.</para>
1068         </listitem>
1069       </varlistentry>
1070     </variablelist>
1071   </refsect1>
1072
1073   <refsect1>
1074     <title>[Tunnel] Section Options</title>
1075
1076     <para>The <literal>[Tunnel]</literal> section only applies for
1077     netdevs of kind
1078     <literal>ipip</literal>,
1079     <literal>sit</literal>,
1080     <literal>gre</literal>,
1081     <literal>gretap</literal>,
1082     <literal>ip6gre</literal>,
1083     <literal>ip6gretap</literal>,
1084     <literal>vti</literal>,
1085     <literal>vti6</literal>,
1086     <literal>ip6tnl</literal>, and
1087     <literal>erspan</literal> and accepts
1088     the following keys:</para>
1089
1090     <variablelist class='network-directives'>
1091       <varlistentry>
1092         <term><varname>Local=</varname></term>
1093         <listitem>
1094           <para>A static local address for tunneled packets. It must be an address on another interface of
1095           this host, or the special value <literal>any</literal>.</para>
1096         </listitem>
1097       </varlistentry>
1098       <varlistentry>
1099         <term><varname>Remote=</varname></term>
1100         <listitem>
1101           <para>The remote endpoint of the tunnel. Takes an IP address or the special value
1102           <literal>any</literal>.</para>
1103         </listitem>
1104       </varlistentry>
1105       <varlistentry>
1106         <term><varname>TOS=</varname></term>
1107         <listitem>
1108           <para>The Type Of Service byte value for a tunnel interface.
1109           For details about the TOS, see the
1110           <ulink url="http://tools.ietf.org/html/rfc1349"> Type of
1111           Service in the Internet Protocol Suite </ulink> document.
1112           </para>
1113         </listitem>
1114       </varlistentry>
1115       <varlistentry>
1116         <term><varname>TTL=</varname></term>
1117         <listitem>
1118           <para>A fixed Time To Live N on tunneled packets. N is a
1119           number in the range 1–255. 0 is a special value meaning that
1120           packets inherit the TTL value. The default value for IPv4
1121           tunnels is: inherit. The default value for IPv6 tunnels is
1122           64.</para>
1123         </listitem>
1124       </varlistentry>
1125       <varlistentry>
1126         <term><varname>DiscoverPathMTU=</varname></term>
1127         <listitem>
1128           <para>Takes a boolean. When true, enables Path MTU Discovery on
1129           the tunnel.</para>
1130         </listitem>
1131       </varlistentry>
1132       <varlistentry>
1133         <term><varname>IPv6FlowLabel=</varname></term>
1134         <listitem>
1135           <para>Configures the 20-bit flow label (see <ulink url="https://tools.ietf.org/html/rfc6437">
1136           RFC 6437</ulink>) field in the IPv6 header (see <ulink url="https://tools.ietf.org/html/rfc2460">
1137           RFC 2460</ulink>), which is used by a node to label packets of a flow.
1138           It is only used for IPv6 tunnels.
1139           A flow label of zero is used to indicate packets that have
1140           not been labeled.
1141           It can be configured to a value in the range 0–0xFFFFF, or be
1142           set to <literal>inherit</literal>, in which case the original flowlabel is used.</para>
1143         </listitem>
1144       </varlistentry>
1145       <varlistentry>
1146         <term><varname>CopyDSCP=</varname></term>
1147         <listitem>
1148           <para>Takes a boolean. When true, the Differentiated Service Code
1149           Point (DSCP) field will be copied to the inner header from
1150           outer header during the decapsulation of an IPv6 tunnel
1151           packet. DSCP is a field in an IP packet that enables different
1152           levels of service to be assigned to network traffic.
1153           Defaults to <literal>no</literal>.
1154           </para>
1155         </listitem>
1156       </varlistentry>
1157       <varlistentry>
1158         <term><varname>EncapsulationLimit=</varname></term>
1159         <listitem>
1160           <para>The Tunnel Encapsulation Limit option specifies how many additional
1161           levels of encapsulation are permitted to be prepended to the packet.
1162           For example, a Tunnel Encapsulation Limit option containing a limit
1163           value of zero means that a packet carrying that option may not enter
1164           another tunnel before exiting the current tunnel.
1165           (see <ulink url="https://tools.ietf.org/html/rfc2473#section-4.1.1"> RFC 2473</ulink>).
1166           The valid range is 0–255 and <literal>none</literal>. Defaults to 4.
1167         </para>
1168         </listitem>
1169       </varlistentry>
1170       <varlistentry>
1171         <term><varname>Key=</varname></term>
1172         <listitem>
1173           <para>The <varname>Key=</varname> parameter specifies the same key to use in
1174           both directions (<varname>InputKey=</varname> and <varname>OutputKey=</varname>).
1175           The <varname>Key=</varname> is either a number or an IPv4 address-like dotted quad.
1176           It is used as mark-configured SAD/SPD entry as part of the lookup key (both in data
1177           and control path) in ip xfrm (framework used to implement IPsec protocol).
1178           See <ulink url="http://man7.org/linux/man-pages/man8/ip-xfrm.8.html">
1179           ip-xfrm — transform configuration</ulink> for details. It is only used for VTI/VTI6,
1180           GRE, GRETAP, and ERSPAN tunnels.</para>
1181         </listitem>
1182       </varlistentry>
1183       <varlistentry>
1184         <term><varname>InputKey=</varname></term>
1185         <listitem>
1186           <para>The <varname>InputKey=</varname> parameter specifies the key to use for input.
1187           The format is same as <varname>Key=</varname>. It is only used for VTI/VTI6, GRE, GRETAP,
1188           and ERSPAN tunnels.</para>
1189         </listitem>
1190       </varlistentry>
1191       <varlistentry>
1192         <term><varname>OutputKey=</varname></term>
1193         <listitem>
1194           <para>The <varname>OutputKey=</varname> parameter specifies the key to use for output.
1195           The format is same as <varname>Key=</varname>. It is only used for VTI/VTI6, GRE, GRETAP,
1196           and ERSPAN tunnels.</para>
1197         </listitem>
1198       </varlistentry>
1199       <varlistentry>
1200         <term><varname>Mode=</varname></term>
1201         <listitem>
1202           <para>An <literal>ip6tnl</literal> tunnel can be in one of three
1203           modes
1204           <literal>ip6ip6</literal> for IPv6 over IPv6,
1205           <literal>ipip6</literal> for IPv4 over IPv6 or
1206           <literal>any</literal> for either.
1207           </para>
1208         </listitem>
1209       </varlistentry>
1210       <varlistentry>
1211         <term><varname>Independent=</varname></term>
1212         <listitem>
1213           <para>Takes a boolean. When true tunnel does not require .network file. Created as "tunnel@NONE".
1214           Defaults to <literal>false</literal>.
1215           </para>
1216         </listitem>
1217       </varlistentry>
1218       <varlistentry>
1219         <term><varname>AssignToLoopback=</varname></term>
1220         <listitem>
1221           <para>Takes a boolean. If set to <literal>yes</literal>, the loopback interface <literal>lo</literal>
1222           is used as the underlying device of the tunnel interface. Defaults to <literal>no</literal>.</para>
1223         </listitem>
1224       </varlistentry>
1225       <varlistentry>
1226         <term><varname>AllowLocalRemote=</varname></term>
1227         <listitem>
1228           <para>Takes a boolean. When true allows tunnel traffic on <varname>ip6tnl</varname> devices where the remote endpoint is a local host address.
1229           When unset, the kernel's default will be used.
1230           </para>
1231         </listitem>
1232       </varlistentry>
1233       <varlistentry>
1234         <term><varname>FooOverUDP=</varname></term>
1235         <listitem>
1236           <para>Takes a boolean. Specifies whether <varname>FooOverUDP=</varname> tunnel is to be configured.
1237           Defaults to false. This takes effects only for IPIP, SIT, GRE, and GRETAP tunnels.
1238           For more detail information see
1239           <ulink url="https://lwn.net/Articles/614348">Foo over UDP</ulink></para>
1240         </listitem>
1241       </varlistentry>
1242       <varlistentry>
1243         <term><varname>FOUDestinationPort=</varname></term>
1244         <listitem>
1245           <para>This setting specifies the UDP destination port for encapsulation.
1246           This field is mandatory when <varname>FooOverUDP=yes</varname>, and is not set by default.</para>
1247         </listitem>
1248       </varlistentry>
1249       <varlistentry>
1250         <term><varname>FOUSourcePort=</varname></term>
1251         <listitem>
1252           <para>This setting specifies the UDP source port for encapsulation. Defaults to <constant>0</constant>
1253           — that is, the source port for packets is left to the network stack to decide.</para>
1254         </listitem>
1255       </varlistentry>
1256       <varlistentry>
1257         <term><varname>Encapsulation=</varname></term>
1258         <listitem>
1259           <para>Accepts the same key as in the <literal>[FooOverUDP]</literal> section.</para>
1260         </listitem>
1261       </varlistentry>
1262       <varlistentry>
1263         <term><varname>IPv6RapidDeploymentPrefix=</varname></term>
1264         <listitem>
1265           <para>Reconfigure the tunnel for <ulink url="https://tools.ietf.org/html/rfc5569">IPv6 Rapid
1266           Deployment</ulink>, also known as 6rd. The value is an ISP-specific IPv6 prefix with a non-zero length. Only
1267           applicable to SIT tunnels.</para>
1268         </listitem>
1269       </varlistentry>
1270       <varlistentry>
1271         <term><varname>ISATAP=</varname></term>
1272         <listitem>
1273           <para>Takes a boolean. If set, configures the tunnel as Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) tunnel.
1274           Only applicable to SIT tunnels. When unset, the kernel's default will be used.</para>
1275         </listitem>
1276       </varlistentry>
1277       <varlistentry>
1278         <term><varname>SerializeTunneledPackets=</varname></term>
1279         <listitem>
1280           <para>Takes a boolean. If set to yes, then packets are serialized. Only applies for GRE,
1281           GRETAP, and ERSPAN tunnels. When unset, the kernel's default will be used.
1282           </para>
1283         </listitem>
1284       </varlistentry>
1285       <varlistentry>
1286         <term><varname>ERSPANIndex=</varname></term>
1287         <listitem>
1288           <para>Specifies the ERSPAN index field for the interface, an integer in the range 1-1048575 associated with
1289           the ERSPAN traffic's source port and direction. This field is mandatory.
1290           </para>
1291         </listitem>
1292       </varlistentry>
1293     </variablelist>
1294   </refsect1>
1295
1296   <refsect1>
1297     <title>[FooOverUDP] Section Options</title>
1298
1299     <para>The <literal>[FooOverUDP]</literal> section only applies for
1300     netdevs of kind <literal>fou</literal> and accepts the
1301     following keys:</para>
1302
1303     <variablelist class='network-directives'>
1304       <varlistentry>
1305         <term><varname>Encapsulation=</varname></term>
1306         <listitem>
1307           <para>Specifies the encapsulation mechanism used to store networking packets of various protocols inside the UDP packets. Supports the following values:
1308
1309           <literal>FooOverUDP</literal> provides the simplest no frills model of UDP encapsulation, it simply encapsulates
1310           packets directly in the UDP payload.
1311           <literal>GenericUDPEncapsulation</literal> is a generic and extensible encapsulation, it allows encapsulation of packets for any IP
1312           protocol and optional data as part of the encapsulation.
1313           For more detailed information see <ulink url="https://lwn.net/Articles/615044">Generic UDP Encapsulation</ulink>.
1314           Defaults to <literal>FooOverUDP</literal>.
1315           </para>
1316         </listitem>
1317       </varlistentry>
1318       <varlistentry>
1319         <term><varname>Port=</varname></term>
1320         <listitem>
1321           <para>Specifies the port number, where the IP encapsulation packets will arrive. Please take note that the packets
1322           will arrive with the encapsulation will be removed. Then they will be manually fed back into the network stack, and sent ahead
1323           for delivery to the real destination. This option is mandatory.</para>
1324         </listitem>
1325       </varlistentry>
1326       <varlistentry>
1327         <term><varname>PeerPort=</varname></term>
1328         <listitem>
1329           <para>Specifies the peer port number. Defaults to unset. Note that when peer port is set <literal>Peer=</literal> address is mandotory.</para>
1330         </listitem>
1331       </varlistentry>
1332       <varlistentry>
1333         <term><varname>Protocol=</varname></term>
1334         <listitem>
1335           <para>The <varname>Protocol=</varname> specifies the protocol number of the packets arriving
1336           at the UDP port. When <varname>Encapsulation=FooOverUDP</varname>, this field is mandatory
1337           and is not set by default. Takes an IP protocol name such as <literal>gre</literal> or
1338           <literal>ipip</literal>, or an integer within the range 1-255. When
1339           <varname>Encapsulation=GenericUDPEncapsulation</varname>, this must not be specified.</para>
1340         </listitem>
1341       </varlistentry>
1342       <varlistentry>
1343         <term><varname>Peer=</varname></term>
1344         <listitem>
1345           <para>Configures peer IP address. Note that when peer address is set <literal>PeerPort=</literal> is mandotory.</para>
1346         </listitem>
1347       </varlistentry>
1348       <varlistentry>
1349         <term><varname>Local=</varname></term>
1350         <listitem>
1351           <para>Configures local IP address.</para>
1352         </listitem>
1353       </varlistentry>
1354     </variablelist>
1355   </refsect1>
1356
1357   <refsect1>
1358     <title>[Peer] Section Options</title>
1359
1360     <para>The <literal>[Peer]</literal> section only applies for
1361     netdevs of kind <literal>veth</literal> and accepts the
1362     following keys:</para>
1363
1364     <variablelist class='network-directives'>
1365       <varlistentry>
1366         <term><varname>Name=</varname></term>
1367         <listitem>
1368           <para>The interface name used when creating the netdev.
1369           This option is compulsory.</para>
1370         </listitem>
1371       </varlistentry>
1372       <varlistentry>
1373         <term><varname>MACAddress=</varname></term>
1374         <listitem>
1375           <para>The peer MACAddress, if not set, it is generated in
1376           the same way as the MAC address of the main
1377           interface.</para>
1378         </listitem>
1379       </varlistentry>
1380     </variablelist>
1381   </refsect1>
1382
1383   <refsect1>
1384     <title>[VXCAN] Section Options</title>
1385
1386     <para>The <literal>[VXCAN]</literal> section only applies for
1387     netdevs of kind <literal>vxcan</literal> and accepts the
1388     following key:</para>
1389
1390     <variablelist class='network-directives'>
1391       <varlistentry>
1392         <term><varname>Peer=</varname></term>
1393         <listitem>
1394           <para>The peer interface name used when creating the netdev.
1395           This option is compulsory.</para>
1396         </listitem>
1397       </varlistentry>
1398     </variablelist>
1399   </refsect1>
1400
1401   <refsect1>
1402     <title>[Tun] Section Options</title>
1403
1404     <para>The <literal>[Tun]</literal> section only applies for
1405     netdevs of kind <literal>tun</literal>, and accepts the following
1406     keys:</para>
1407
1408     <variablelist class='network-directives'>
1409       <varlistentry>
1410         <term><varname>MultiQueue=</varname></term>
1411         <listitem><para>Takes a boolean. Configures whether
1412         to use multiple file descriptors (queues) to parallelize
1413         packets sending and receiving. Defaults to
1414         <literal>no</literal>.</para>
1415         </listitem>
1416       </varlistentry>
1417       <varlistentry>
1418         <term><varname>PacketInfo=</varname></term>
1419         <listitem><para>Takes a boolean. Configures whether
1420         packets should be prepended with four extra bytes (two flag
1421         bytes and two protocol bytes). If disabled, it indicates that
1422         the packets will be pure IP packets. Defaults to
1423         <literal>no</literal>.</para>
1424         </listitem>
1425       </varlistentry>
1426       <varlistentry>
1427         <term><varname>VNetHeader=</varname></term>
1428         <listitem><para>Takes a boolean. Configures
1429         IFF_VNET_HDR flag for a tun or tap device. It allows sending
1430         and receiving larger Generic Segmentation Offload (GSO)
1431         packets. This may increase throughput significantly.
1432         Defaults to
1433         <literal>no</literal>.</para>
1434         </listitem>
1435       </varlistentry>
1436       <varlistentry>
1437         <term><varname>User=</varname></term>
1438         <listitem><para>User to grant access to the
1439         <filename>/dev/net/tun</filename> device.</para>
1440         </listitem>
1441       </varlistentry>
1442       <varlistentry>
1443         <term><varname>Group=</varname></term>
1444         <listitem><para>Group to grant access to the
1445         <filename>/dev/net/tun</filename> device.</para>
1446         </listitem>
1447       </varlistentry>
1448     </variablelist>
1449   </refsect1>
1450
1451   <refsect1>
1452     <title>[Tap] Section Options</title>
1453
1454     <para>The <literal>[Tap]</literal> section only applies for
1455     netdevs of kind <literal>tap</literal>, and accepts the same keys
1456     as the <literal>[Tun]</literal> section.</para>
1457   </refsect1>
1458
1459   <refsect1>
1460     <title>[WireGuard] Section Options</title>
1461
1462     <para>The <literal>[WireGuard]</literal> section accepts the following
1463     keys:</para>
1464
1465     <variablelist class='network-directives'>
1466       <varlistentry>
1467         <term><varname>PrivateKey=</varname></term>
1468         <listitem>
1469           <para>The Base64 encoded private key for the interface. It can be
1470           generated using the <command>wg genkey</command> command
1471           (see <citerefentry project="wireguard"><refentrytitle>wg</refentrytitle><manvolnum>8</manvolnum></citerefentry>).
1472           This option or <varname>PrivateKeyFile=</varname> is mandatory to use WireGuard.
1473           Note that because this information is secret, you may want to set
1474           the permissions of the .netdev file to be owned by <literal>root:systemd-network</literal>
1475           with a <literal>0640</literal> file mode.</para>
1476         </listitem>
1477       </varlistentry>
1478       <varlistentry>
1479         <term><varname>PrivateKeyFile=</varname></term>
1480         <listitem>
1481           <para>Takes an absolute path to a file which contains the Base64 encoded private key for the interface.
1482           When this option is specified, then <varname>PrivateKey=</varname> is ignored.
1483           Note that the file must be readable by the user <literal>systemd-network</literal>, so it
1484           should be, e.g., owned by <literal>root:systemd-network</literal> with a
1485           <literal>0640</literal> file mode.</para>
1486         </listitem>
1487       </varlistentry>
1488       <varlistentry>
1489         <term><varname>ListenPort=</varname></term>
1490         <listitem>
1491           <para>Sets UDP port for listening. Takes either value between 1 and 65535
1492           or <literal>auto</literal>. If <literal>auto</literal> is specified,
1493           the port is automatically generated based on interface name.
1494           Defaults to <literal>auto</literal>.</para>
1495         </listitem>
1496       </varlistentry>
1497       <varlistentry>
1498         <term><varname>FirewallMark=</varname></term>
1499         <listitem>
1500           <para>Sets a firewall mark on outgoing WireGuard packets from this interface. Takes a number between 1 and 4294967295.</para>
1501         </listitem>
1502       </varlistentry>
1503     </variablelist>
1504   </refsect1>
1505
1506   <refsect1>
1507     <title>[WireGuardPeer] Section Options</title>
1508
1509     <para>The <literal>[WireGuardPeer]</literal> section accepts the following
1510     keys:</para>
1511
1512     <variablelist class='network-directives'>
1513       <varlistentry>
1514         <term><varname>PublicKey=</varname></term>
1515         <listitem>
1516           <para>Sets a Base64 encoded public key calculated by <command>wg pubkey</command>
1517           (see <citerefentry project="wireguard"><refentrytitle>wg</refentrytitle><manvolnum>8</manvolnum></citerefentry>)
1518           from a private key, and usually transmitted out of band to the
1519           author of the configuration file. This option is mandatory for this
1520           section.</para>
1521         </listitem>
1522       </varlistentry>
1523       <varlistentry>
1524         <term><varname>PresharedKey=</varname></term>
1525         <listitem>
1526           <para>Optional preshared key for the interface. It can be generated
1527           by the <command>wg genpsk</command> command. This option adds an
1528           additional layer of symmetric-key cryptography to be mixed into the
1529           already existing public-key cryptography, for post-quantum
1530           resistance.
1531           Note that because this information is secret, you may want to set
1532           the permissions of the .netdev file to be owned by <literal>root:systemd-networkd</literal>
1533           with a <literal>0640</literal> file mode.</para>
1534         </listitem>
1535       </varlistentry>
1536       <varlistentry>
1537         <term><varname>PresharedKeyFile=</varname></term>
1538         <listitem>
1539           <para>Takes an absolute path to a file which contains the Base64 encoded preshared key for the
1540           peer. When this option is specified, then <varname>PresharedKey=</varname> is ignored.
1541           Note that the file must be readable by the user <literal>systemd-network</literal>, so it
1542           should be, e.g., owned by <literal>root:systemd-network</literal> with a
1543           <literal>0640</literal> file mode.</para>
1544         </listitem>
1545       </varlistentry>
1546       <varlistentry>
1547         <term><varname>AllowedIPs=</varname></term>
1548         <listitem>
1549           <para>Sets a comma-separated list of IP (v4 or v6) addresses with CIDR masks
1550           from which this peer is allowed to send incoming traffic and to
1551           which outgoing traffic for this peer is directed. The catch-all
1552           0.0.0.0/0 may be specified for matching all IPv4 addresses, and
1553           ::/0 may be specified for matching all IPv6 addresses. </para>
1554         </listitem>
1555       </varlistentry>
1556       <varlistentry>
1557         <term><varname>Endpoint=</varname></term>
1558         <listitem>
1559           <para>Sets an endpoint IP address or hostname, followed by a colon, and then
1560           a port number. This endpoint will be updated automatically once to
1561           the most recent source IP address and port of correctly
1562           authenticated packets from the peer at configuration time.</para>
1563         </listitem>
1564       </varlistentry>
1565       <varlistentry>
1566         <term><varname>PersistentKeepalive=</varname></term>
1567         <listitem>
1568           <para>Sets a seconds interval, between 1 and 65535 inclusive, of how often
1569           to send an authenticated empty packet to the peer for the purpose
1570           of keeping a stateful firewall or NAT mapping valid persistently.
1571           For example, if the interface very rarely sends traffic, but it
1572           might at anytime receive traffic from a peer, and it is behind NAT,
1573           the interface might benefit from having a persistent keepalive
1574           interval of 25 seconds. If set to 0 or "off", this option is
1575           disabled. By default or when unspecified, this option is off.
1576           Most users will not need this.</para>
1577         </listitem>
1578       </varlistentry>
1579     </variablelist>
1580   </refsect1>
1581
1582   <refsect1>
1583     <title>[Bond] Section Options</title>
1584
1585     <para>The <literal>[Bond]</literal> section accepts the following
1586     key:</para>
1587
1588     <variablelist class='network-directives'>
1589       <varlistentry>
1590         <term><varname>Mode=</varname></term>
1591         <listitem>
1592           <para>Specifies one of the bonding policies. The default is
1593           <literal>balance-rr</literal> (round robin). Possible values are
1594           <literal>balance-rr</literal>,
1595           <literal>active-backup</literal>,
1596           <literal>balance-xor</literal>,
1597           <literal>broadcast</literal>,
1598           <literal>802.3ad</literal>,
1599           <literal>balance-tlb</literal>, and
1600           <literal>balance-alb</literal>.
1601           </para>
1602         </listitem>
1603       </varlistentry>
1604
1605       <varlistentry>
1606         <term><varname>TransmitHashPolicy=</varname></term>
1607         <listitem>
1608           <para>Selects the transmit hash policy to use for slave
1609           selection in balance-xor, 802.3ad, and tlb modes. Possible
1610           values are
1611           <literal>layer2</literal>,
1612           <literal>layer3+4</literal>,
1613           <literal>layer2+3</literal>,
1614           <literal>encap2+3</literal>, and
1615           <literal>encap3+4</literal>.
1616           </para>
1617         </listitem>
1618       </varlistentry>
1619
1620       <varlistentry>
1621         <term><varname>LACPTransmitRate=</varname></term>
1622         <listitem>
1623           <para>Specifies the rate with which link partner transmits
1624           Link Aggregation Control Protocol Data Unit packets in
1625           802.3ad mode. Possible values are <literal>slow</literal>,
1626           which requests partner to transmit LACPDUs every 30 seconds,
1627           and <literal>fast</literal>, which requests partner to
1628           transmit LACPDUs every second. The default value is
1629           <literal>slow</literal>.</para>
1630         </listitem>
1631       </varlistentry>
1632
1633       <varlistentry>
1634         <term><varname>MIIMonitorSec=</varname></term>
1635         <listitem>
1636           <para>Specifies the frequency that Media Independent
1637           Interface link monitoring will occur. A value of zero
1638           disables MII link monitoring. This value is rounded down to
1639           the nearest millisecond. The default value is 0.</para>
1640         </listitem>
1641       </varlistentry>
1642
1643       <varlistentry>
1644         <term><varname>UpDelaySec=</varname></term>
1645         <listitem>
1646           <para>Specifies the delay before a link is enabled after a
1647           link up status has been detected. This value is rounded down
1648           to a multiple of MIIMonitorSec. The default value is
1649           0.</para>
1650         </listitem>
1651       </varlistentry>
1652
1653       <varlistentry>
1654         <term><varname>DownDelaySec=</varname></term>
1655         <listitem>
1656           <para>Specifies the delay before a link is disabled after a
1657           link down status has been detected. This value is rounded
1658           down to a multiple of MIIMonitorSec. The default value is
1659           0.</para>
1660         </listitem>
1661       </varlistentry>
1662
1663       <varlistentry>
1664         <term><varname>LearnPacketIntervalSec=</varname></term>
1665         <listitem>
1666           <para>Specifies the number of seconds between instances where the bonding
1667           driver sends learning packets to each slave peer switch.
1668           The valid range is 1–0x7fffffff; the default value is 1. This option
1669           has an effect only for the balance-tlb and balance-alb modes.</para>
1670         </listitem>
1671       </varlistentry>
1672
1673       <varlistentry>
1674         <term><varname>AdSelect=</varname></term>
1675         <listitem>
1676           <para>Specifies the 802.3ad aggregation selection logic to use. Possible values are
1677           <literal>stable</literal>,
1678           <literal>bandwidth</literal> and
1679           <literal>count</literal>.
1680           </para>
1681         </listitem>
1682       </varlistentry>
1683
1684       <varlistentry>
1685         <term><varname>AdActorSystemPriority=</varname></term>
1686         <listitem>
1687           <para>Specifies the 802.3ad actor system priority. Ranges [1-65535].</para>
1688         </listitem>
1689       </varlistentry>
1690
1691       <varlistentry>
1692         <term><varname>AdUserPortKey=</varname></term>
1693         <listitem>
1694           <para>Specifies the 802.3ad user defined portion of the port key. Ranges [0-1023].</para>
1695         </listitem>
1696       </varlistentry>
1697
1698       <varlistentry>
1699         <term><varname>AdActorSystem=</varname></term>
1700         <listitem>
1701           <para>Specifies the 802.3ad system mac address. This can not be either NULL or Multicast.</para>
1702         </listitem>
1703       </varlistentry>
1704
1705       <varlistentry>
1706         <term><varname>FailOverMACPolicy=</varname></term>
1707         <listitem>
1708           <para>Specifies whether the active-backup mode should set all slaves to
1709           the same MAC address at the time of enslavement or, when enabled, to perform special handling of the
1710           bond's MAC address in accordance with the selected policy. The default policy is none.
1711           Possible values are
1712           <literal>none</literal>,
1713           <literal>active</literal> and
1714           <literal>follow</literal>.
1715           </para>
1716         </listitem>
1717       </varlistentry>
1718
1719       <varlistentry>
1720         <term><varname>ARPValidate=</varname></term>
1721         <listitem>
1722           <para>Specifies whether or not ARP probes and replies should be
1723           validated in any mode that supports ARP monitoring, or whether
1724           non-ARP traffic should be filtered (disregarded) for link
1725           monitoring purposes. Possible values are
1726           <literal>none</literal>,
1727           <literal>active</literal>,
1728           <literal>backup</literal> and
1729           <literal>all</literal>.
1730           </para>
1731         </listitem>
1732       </varlistentry>
1733
1734       <varlistentry>
1735         <term><varname>ARPIntervalSec=</varname></term>
1736         <listitem>
1737           <para>Specifies the ARP link monitoring frequency in milliseconds.
1738           A value of 0 disables ARP monitoring. The default value is 0.
1739           </para>
1740         </listitem>
1741       </varlistentry>
1742
1743       <varlistentry>
1744         <term><varname>ARPIPTargets=</varname></term>
1745         <listitem>
1746           <para>Specifies the IP addresses to use as ARP monitoring peers when
1747           ARPIntervalSec is greater than 0. These are the targets of the ARP request
1748           sent to determine the health of the link to the targets.
1749           Specify these values in IPv4 dotted decimal format. At least one IP
1750           address must be given for ARP monitoring to function. The
1751           maximum number of targets that can be specified is 16. The
1752           default value is no IP addresses.
1753           </para>
1754         </listitem>
1755       </varlistentry>
1756
1757       <varlistentry>
1758         <term><varname>ARPAllTargets=</varname></term>
1759         <listitem>
1760           <para>Specifies the quantity of ARPIPTargets that must be reachable
1761           in order for the ARP monitor to consider a slave as being up.
1762           This option affects only active-backup mode for slaves with
1763           ARPValidate enabled. Possible values are
1764           <literal>any</literal> and
1765           <literal>all</literal>.
1766           </para>
1767         </listitem>
1768       </varlistentry>
1769
1770       <varlistentry>
1771         <term><varname>PrimaryReselectPolicy=</varname></term>
1772         <listitem>
1773           <para>Specifies the reselection policy for the primary slave.  This
1774           affects how the primary slave is chosen to become the active slave
1775           when failure of the active slave or recovery of the primary slave
1776           occurs. This option is designed to prevent flip-flopping between
1777           the primary slave and other slaves.  Possible values are
1778           <literal>always</literal>,
1779           <literal>better</literal> and
1780           <literal>failure</literal>.
1781           </para>
1782         </listitem>
1783       </varlistentry>
1784
1785       <varlistentry>
1786         <term><varname>ResendIGMP=</varname></term>
1787         <listitem>
1788           <para>Specifies the number of IGMP membership reports to be issued after
1789           a failover event. One membership report is issued immediately after
1790           the failover, subsequent packets are sent in each 200ms interval.
1791           The valid range is 0–255. Defaults to 1. A value of 0
1792           prevents the IGMP membership report from being issued in response
1793           to the failover event.
1794           </para>
1795         </listitem>
1796       </varlistentry>
1797
1798       <varlistentry>
1799         <term><varname>PacketsPerSlave=</varname></term>
1800         <listitem>
1801           <para>Specify the number of packets to transmit through a slave before
1802           moving to the next one. When set to 0, then a slave is chosen at
1803           random. The valid range is 0–65535. Defaults to 1. This option
1804           only has effect when in balance-rr mode.
1805           </para>
1806         </listitem>
1807       </varlistentry>
1808
1809       <varlistentry>
1810         <term><varname>GratuitousARP=</varname></term>
1811         <listitem>
1812           <para>Specify the number of peer notifications (gratuitous ARPs and
1813           unsolicited IPv6 Neighbor Advertisements) to be issued after a
1814           failover event.  As soon as the link is up on the new slave,
1815           a peer notification is sent on the  bonding device and each
1816           VLAN sub-device.  This is repeated at each link monitor interval
1817           (ARPIntervalSec or MIIMonitorSec, whichever is active) if the number is
1818           greater than 1. The valid range is 0–255. The default value is 1.
1819           These options affect only the active-backup mode.
1820           </para>
1821         </listitem>
1822       </varlistentry>
1823
1824       <varlistentry>
1825         <term><varname>AllSlavesActive=</varname></term>
1826         <listitem>
1827           <para>Takes a boolean. Specifies that duplicate frames (received on inactive ports)
1828           should be dropped when false, or delivered when true. Normally, bonding will drop
1829           duplicate frames (received on inactive ports), which is desirable for
1830           most users. But there are some times it is nice to allow duplicate
1831           frames to be delivered. The default value is false (drop duplicate frames
1832           received on inactive ports).
1833           </para>
1834         </listitem>
1835       </varlistentry>
1836
1837       <varlistentry>
1838         <term><varname>DynamicTransmitLoadBalancing=</varname></term>
1839         <listitem>
1840           <para>Takes a boolean. Specifies if dynamic shuffling of flows is enabled. Applies only
1841           for balance-tlb mode. Defaults to unset.
1842           </para>
1843         </listitem>
1844       </varlistentry>
1845
1846       <varlistentry>
1847         <term><varname>MinLinks=</varname></term>
1848         <listitem>
1849           <para>Specifies the minimum number of links that must be active before
1850           asserting carrier. The default value is 0.
1851           </para>
1852         </listitem>
1853       </varlistentry>
1854     </variablelist>
1855
1856     <para>For more detail information see
1857     <ulink url="https://www.kernel.org/doc/Documentation/networking/bonding.txt">
1858     Linux Ethernet Bonding Driver HOWTO</ulink></para>
1859   </refsect1>
1860
1861   <refsect1>
1862     <title>[Xfrm] Section Options</title>
1863
1864     <para>The <literal>[Xfrm]</literal> section accepts the following
1865     keys:</para>
1866
1867     <variablelist class='network-directives'>
1868       <varlistentry>
1869         <term><varname>InterfaceId=</varname></term>
1870         <listitem>
1871           <para>Sets the ID/key of the xfrm interface which needs to be associated with a SA/policy.
1872           Can be decimal or hexadecimal, valid range is 0-0xffffffff, defaults to 0.</para>
1873         </listitem>
1874       </varlistentry>
1875       <varlistentry>
1876         <term><varname>Independent=</varname></term>
1877         <listitem>
1878           <para>Takes a boolean. If set to <literal>no</literal>, the xfrm interface should have an
1879           underlying device which can be used for hardware offloading. Defaults to <literal>no</literal>.
1880           See <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1881           for how to configure the underlying device.</para>
1882         </listitem>
1883       </varlistentry>
1884     </variablelist>
1885
1886     <para>For more detail information see
1887       <ulink url="https://lwn.net/Articles/757391">
1888         Virtual xfrm interfaces</ulink></para>
1889   </refsect1>
1890
1891   <refsect1>
1892     <title>[VRF] Section Options</title>
1893     <para>The <literal>[VRF]</literal> section only applies for
1894     netdevs of kind <literal>vrf</literal> and accepts the
1895     following key:</para>
1896
1897     <variablelist class='network-directives'>
1898       <varlistentry>
1899         <term><varname>Table=</varname></term>
1900         <listitem>
1901           <para>The numeric routing table identifier. This option is compulsory.</para>
1902         </listitem>
1903       </varlistentry>
1904     </variablelist>
1905   </refsect1>
1906
1907   <refsect1>
1908     <title>Examples</title>
1909     <example>
1910       <title>/etc/systemd/network/25-bridge.netdev</title>
1911
1912       <programlisting>[NetDev]
1913 Name=bridge0
1914 Kind=bridge</programlisting>
1915     </example>
1916
1917     <example>
1918       <title>/etc/systemd/network/25-vlan1.netdev</title>
1919
1920       <programlisting>[Match]
1921 Virtualization=no
1922
1923 [NetDev]
1924 Name=vlan1
1925 Kind=vlan
1926
1927 [VLAN]
1928 Id=1</programlisting>
1929     </example>
1930     <example>
1931       <title>/etc/systemd/network/25-ipip.netdev</title>
1932       <programlisting>[NetDev]
1933 Name=ipip-tun
1934 Kind=ipip
1935 MTUBytes=1480
1936
1937 [Tunnel]
1938 Local=192.168.223.238
1939 Remote=192.169.224.239
1940 TTL=64</programlisting>
1941     </example>
1942     <example>
1943       <title>/etc/systemd/network/1-fou-tunnel.netdev</title>
1944       <programlisting>[NetDev]
1945 Name=fou-tun
1946 Kind=fou
1947
1948 [FooOverUDP]
1949 Port=5555
1950 Protocol=4
1951       </programlisting>
1952     </example>
1953     <example>
1954       <title>/etc/systemd/network/25-fou-ipip.netdev</title>
1955       <programlisting>[NetDev]
1956 Name=ipip-tun
1957 Kind=ipip
1958
1959 [Tunnel]
1960 Independent=yes
1961 Local=10.65.208.212
1962 Remote=10.65.208.211
1963 FooOverUDP=yes
1964 FOUDestinationPort=5555
1965       </programlisting>
1966     </example>
1967     <example>
1968       <title>/etc/systemd/network/25-tap.netdev</title>
1969       <programlisting>[NetDev]
1970 Name=tap-test
1971 Kind=tap
1972
1973 [Tap]
1974 MultiQueue=yes
1975 PacketInfo=yes</programlisting> </example>
1976
1977     <example>
1978       <title>/etc/systemd/network/25-sit.netdev</title>
1979       <programlisting>[NetDev]
1980 Name=sit-tun
1981 Kind=sit
1982 MTUBytes=1480
1983
1984 [Tunnel]
1985 Local=10.65.223.238
1986 Remote=10.65.223.239</programlisting>
1987     </example>
1988
1989     <example>
1990       <title>/etc/systemd/network/25-6rd.netdev</title>
1991       <programlisting>[NetDev]
1992 Name=6rd-tun
1993 Kind=sit
1994 MTUBytes=1480
1995
1996 [Tunnel]
1997 Local=10.65.223.238
1998 IPv6RapidDeploymentPrefix=2602::/24</programlisting>
1999     </example>
2000
2001     <example>
2002       <title>/etc/systemd/network/25-gre.netdev</title>
2003       <programlisting>[NetDev]
2004 Name=gre-tun
2005 Kind=gre
2006 MTUBytes=1480
2007
2008 [Tunnel]
2009 Local=10.65.223.238
2010 Remote=10.65.223.239</programlisting>
2011     </example>
2012
2013     <example>
2014       <title>/etc/systemd/network/25-vti.netdev</title>
2015
2016       <programlisting>[NetDev]
2017 Name=vti-tun
2018 Kind=vti
2019 MTUBytes=1480
2020
2021 [Tunnel]
2022 Local=10.65.223.238
2023 Remote=10.65.223.239</programlisting>
2024     </example>
2025
2026     <example>
2027       <title>/etc/systemd/network/25-veth.netdev</title>
2028       <programlisting>[NetDev]
2029 Name=veth-test
2030 Kind=veth
2031
2032 [Peer]
2033 Name=veth-peer</programlisting>
2034     </example>
2035
2036     <example>
2037       <title>/etc/systemd/network/25-bond.netdev</title>
2038       <programlisting>[NetDev]
2039 Name=bond1
2040 Kind=bond
2041
2042 [Bond]
2043 Mode=802.3ad
2044 TransmitHashPolicy=layer3+4
2045 MIIMonitorSec=1s
2046 LACPTransmitRate=fast
2047 </programlisting>
2048     </example>
2049
2050     <example>
2051       <title>/etc/systemd/network/25-dummy.netdev</title>
2052       <programlisting>[NetDev]
2053 Name=dummy-test
2054 Kind=dummy
2055 MACAddress=12:34:56:78:9a:bc</programlisting>
2056     </example>
2057     <example>
2058       <title>/etc/systemd/network/25-vrf.netdev</title>
2059       <para>Create a VRF interface with table 42.</para>
2060       <programlisting>[NetDev]
2061 Name=vrf-test
2062 Kind=vrf
2063
2064 [VRF]
2065 Table=42</programlisting>
2066     </example>
2067
2068     <example>
2069       <title>/etc/systemd/network/25-macvtap.netdev</title>
2070       <para>Create a MacVTap device.</para>
2071       <programlisting>[NetDev]
2072 Name=macvtap-test
2073 Kind=macvtap
2074       </programlisting>
2075     </example>
2076     <example>
2077       <title>/etc/systemd/network/25-wireguard.netdev</title>
2078       <programlisting>[NetDev]
2079 Name=wg0
2080 Kind=wireguard
2081
2082 [WireGuard]
2083 PrivateKey=EEGlnEPYJV//kbvvIqxKkQwOiS+UENyPncC4bF46ong=
2084 ListenPort=51820
2085
2086 [WireGuardPeer]
2087 PublicKey=RDf+LSpeEre7YEIKaxg+wbpsNV7du+ktR99uBEtIiCA=
2088 AllowedIPs=fd31:bf08:57cb::/48,192.168.26.0/24
2089 Endpoint=wireguard.example.com:51820</programlisting>
2090     </example>
2091
2092     <example>
2093       <title>/etc/systemd/network/27-xfrm.netdev</title>
2094       <programlisting>[Xfrm]
2095 Name=xfrm0
2096 Kind=xfrm
2097
2098 [Xfrm]
2099 Independent=yes</programlisting>
2100     </example>
2101   </refsect1>
2102
2103   <refsect1>
2104     <title>See Also</title>
2105     <para>
2106       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
2107       <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
2108       <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2109       <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2110     </para>
2111   </refsect1>
2112
2113 </refentry>