man/systemd.netdev.xml

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