1 <?xml version='
1.0'
?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 SPDX-License-Identifier: LGPL-2.1+
9 <refentry id=
"systemd.netdev" conditional='ENABLE_NETWORKD'
>
12 <title>systemd.network
</title>
13 <productname>systemd
</productname>
17 <refentrytitle>systemd.netdev
</refentrytitle>
18 <manvolnum>5</manvolnum>
22 <refname>systemd.netdev
</refname>
23 <refpurpose>Virtual Network Device configuration
</refpurpose>
27 <para><filename><replaceable>netdev
</replaceable>.netdev
</filename></para>
31 <title>Description
</title>
33 <para>Network setup is performed by
34 <citerefentry><refentrytitle>systemd-networkd
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
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
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>
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>
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>
72 <title>Supported netdev kinds
</title>
74 <para>The following kinds of virtual network devices may be
75 configured in
<filename>.netdev
</filename> files:
</para>
78 <title>Supported kinds of virtual network devices
</title>
81 <colspec colname='kind'
/>
82 <colspec colname='explanation'
/>
85 <entry>Description
</entry>
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>
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>
94 <row><entry><varname>dummy
</varname></entry>
95 <entry>A dummy device drops all packets sent to it.
</entry></row>
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>
100 <row><entry><varname>gretap
</varname></entry>
101 <entry>A Level
2 GRE tunnel over IPv4.
</entry></row>
103 <row><entry><varname>ip6gre
</varname></entry>
104 <entry>A Level
3 GRE tunnel over IPv6.
</entry></row>
106 <row><entry><varname>ip6tnl
</varname></entry>
107 <entry>An IPv4 or IPv6 tunnel over IPv6
</entry></row>
109 <row><entry><varname>ip6gretap
</varname></entry>
110 <entry>A Level
2 GRE tunnel over IPv6.
</entry></row>
112 <row><entry><varname>ipip
</varname></entry>
113 <entry>An IPv4 over IPv4 tunnel.
</entry></row>
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>
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>
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>
124 <row><entry><varname>sit
</varname></entry>
125 <entry>An IPv6 over IPv4 tunnel.
</entry></row>
127 <row><entry><varname>tap
</varname></entry>
128 <entry>A persistent Level
2 tunnel between a network device and a device node.
</entry></row>
130 <row><entry><varname>tun
</varname></entry>
131 <entry>A persistent Level
3 tunnel between a network device and a device node.
</entry></row>
133 <row><entry><varname>veth
</varname></entry>
134 <entry>An Ethernet tunnel between a pair of network devices.
</entry></row>
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>
139 <row><entry><varname>vti
</varname></entry>
140 <entry>An IPv4 over IPSec tunnel.
</entry></row>
142 <row><entry><varname>vti6
</varname></entry>
143 <entry>An IPv6 over IPSec tunnel.
</entry></row>
145 <row><entry><varname>vxlan
</varname></entry>
146 <entry>A virtual extensible LAN (vxlan), for connecting Cloud computing deployments.
</entry></row>
148 <row><entry><varname>geneve
</varname></entry>
149 <entry>A GEneric NEtwork Virtualization Encapsulation (GENEVE) netdev driver.
</entry></row>
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>
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>
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.
161 <row><entry><varname>wireguard
</varname></entry>
162 <entry>WireGuard Secure Network Tunnel.
</entry></row>
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>
173 <title>[Match] Section Options
</title>
175 <para>A virtual network device is only created if the
176 <literal>[Match]
</literal> section matches the current
177 environment, or if the section is empty. The following keys are
180 <variablelist class='network-directives'
>
182 <term><varname>Host=
</varname></term>
184 <para>Matches against the hostname or machine ID of the
185 host. See
<literal>ConditionHost=
</literal> in
186 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
192 <term><varname>Virtualization=
</varname></term>
194 <para>Checks whether the system is executed in a virtualized
195 environment and optionally test whether it is a specific
197 <literal>ConditionVirtualization=
</literal> in
198 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
204 <term><varname>KernelCommandLine=
</varname></term>
206 <para>Checks whether a specific kernel command line option
207 is set (or if prefixed with the exclamation mark unset). See
208 <literal>ConditionKernelCommandLine=
</literal> in
209 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
215 <term><varname>KernelVersion=
</varname></term>
217 <para>Checks whether the kernel version (as reported by
<command>uname -r
</command>) matches a certain
218 expression (or if prefixed with the exclamation mark does not match it). See
219 <literal>ConditionKernelVersion=
</literal> in
220 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details.
225 <term><varname>Architecture=
</varname></term>
227 <para>Checks whether the system is running on a specific
228 architecture. See
<literal>ConditionArchitecture=
</literal> in
229 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
239 <title>[NetDev] Section Options
</title>
241 <para>The
<literal>[NetDev]
</literal> section accepts the
242 following keys:
</para>
244 <variablelist class='network-directives'
>
246 <term><varname>Description=
</varname></term>
248 <para>A free-form description of the netdev.
</para>
252 <term><varname>Name=
</varname></term>
254 <para>The interface name used when creating the netdev.
255 This option is compulsory.
</para>
259 <term><varname>Kind=
</varname></term>
261 <para>The netdev kind. This option is compulsory. See the
262 <literal>Supported netdev kinds
</literal> section for the
267 <term><varname>MTUBytes=
</varname></term>
269 <para>The maximum transmission unit in bytes to set for the device. The usual suffixes K, M, G,
270 are supported and are understood to the base of
1024. For
<literal>tun
</literal> or
271 <literal>tap
</literal> devices,
<varname>MTUBytes=
</varname> setting is not currently supported in
272 <literal>[NetDev]
</literal> section. Please specify it in
<literal>[Link]
</literal> section of
274 <citerefentry><refentrytitle>systemd.network
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
279 <term><varname>MACAddress=
</varname></term>
281 <para>The MAC address to use for the device. If none is
282 given, one is generated based on the interface name and
284 <citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
285 For
<literal>tun
</literal> or
<literal>tap
</literal> devices,
<varname>MACAddress=
</varname> setting
286 is not currently supported in
<literal>[NetDev]
</literal> section. Please specify it in
287 <literal>[Link]
</literal> section of corresponding
288 <citerefentry><refentrytitle>systemd.network
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
296 <title>[Bridge] Section Options
</title>
298 <para>The
<literal>[Bridge]
</literal> section only applies for
299 netdevs of kind
<literal>bridge
</literal>, and accepts the
300 following keys:
</para>
302 <variablelist class='network-directives'
>
304 <term><varname>HelloTimeSec=
</varname></term>
306 <para>HelloTimeSec specifies the number of seconds between two hello packets
307 sent out by the root bridge and the designated bridges. Hello packets are
308 used to communicate information about the topology throughout the entire
309 bridged local area network.
</para>
313 <term><varname>MaxAgeSec=
</varname></term>
315 <para>MaxAgeSec specifies the number of seconds of maximum message age.
316 If the last seen (received) hello packet is more than this number of
317 seconds old, the bridge in question will start the takeover procedure
318 in attempt to become the Root Bridge itself.
</para>
322 <term><varname>ForwardDelaySec=
</varname></term>
324 <para>ForwardDelaySec specifies the number of seconds spent in each
325 of the Listening and Learning states before the Forwarding state is entered.
</para>
329 <term><varname>AgeingTimeSec=
</varname></term>
331 <para>This specifies the number of seconds a MAC Address will be kept in
332 the forwarding database after having a packet received from this MAC Address.
</para>
336 <term><varname>Priority=
</varname></term>
338 <para>The priority of the bridge. An integer between
0 and
65535. A lower value
339 means higher priority. The bridge having the lowest priority will be elected as root bridge.
</para>
343 <term><varname>GroupForwardMask=
</varname></term>
345 <para>A
16-bit bitmask represented as an integer which allows forwarding of link
346 local frames with
802.1D reserved addresses (
01:
80:C2:
00:
00:
0X). A logical AND
347 is performed between the specified bitmask and the exponentiation of
2^X, the
348 lower nibble of the last octet of the MAC address. For example, a value of
8
349 would allow forwarding of frames addressed to
01:
80:C2:
00:
00:
03 (
802.1X PAE).
</para>
353 <term><varname>DefaultPVID=
</varname></term>
355 <para>This specifies the default port VLAN ID of a newly attached bridge port.
356 Set this to an integer in the range
1–
4094 or
<literal>none
</literal> to disable the PVID.
</para>
360 <term><varname>MulticastQuerier=
</varname></term>
362 <para>A boolean. This setting controls the IFLA_BR_MCAST_QUERIER option in the kernel.
363 If enabled, the kernel will send general ICMP queries from a zero source address.
364 This feature should allow faster convergence on startup, but it causes some
365 multicast-aware switches to misbehave and disrupt forwarding of multicast packets.
366 When unset, the kernel's default setting applies.
371 <term><varname>MulticastSnooping=
</varname></term>
373 <para>A boolean. This setting controls the IFLA_BR_MCAST_SNOOPING option in the kernel.
374 If enabled, IGMP snooping monitors the Internet Group Management Protocol (IGMP) traffic
375 between hosts and multicast routers. When unset, the kernel's default setting applies.
380 <term><varname>VLANFiltering=
</varname></term>
382 <para>A boolean. This setting controls the IFLA_BR_VLAN_FILTERING option in the kernel.
383 If enabled, the bridge will be started in VLAN-filtering mode. When unset, the kernel's
384 default setting applies.
389 <term><varname>STP=
</varname></term>
391 <para>A boolean. This enables the bridge's Spanning Tree Protocol (STP). When unset,
392 the kernel's default setting applies.
400 <title>[VLAN] Section Options
</title>
402 <para>The
<literal>[VLAN]
</literal> section only applies for
403 netdevs of kind
<literal>vlan
</literal>, and accepts the
404 following key:
</para>
406 <variablelist class='network-directives'
>
408 <term><varname>Id=
</varname></term>
410 <para>The VLAN ID to use. An integer in the range
0–
4094.
411 This option is compulsory.
</para>
415 <term><varname>GVRP=
</varname></term>
417 <para>The Generic VLAN Registration Protocol (GVRP) is a protocol that
418 allows automatic learning of VLANs on a network. A boolean. When unset,
419 the kernel's default setting applies.
</para>
423 <term><varname>MVRP=
</varname></term>
425 <para>Multiple VLAN Registration Protocol (MVRP) formerly known as GARP VLAN
426 Registration Protocol (GVRP) is a standards-based Layer
2 network protocol,
427 for automatic configuration of VLAN information on switches. It was defined
428 in the
802.1ak amendment to
802.1Q-
2005. A boolean. When unset, the kernel's
429 default setting applies.
</para>
433 <term><varname>LooseBinding=
</varname></term>
435 <para>The VLAN loose binding mode, in which only the operational state is passed
436 from the parent to the associated VLANs, but the VLAN device state is not changed.
437 A boolean. When unset, the kernel's default setting applies.
</para>
441 <term><varname>ReorderHeader=
</varname></term>
443 <para>The VLAN reorder header is set VLAN interfaces behave like physical interfaces.
444 A boolean. When unset, the kernel's default setting applies.
</para>
451 <title>[MACVLAN] Section Options
</title>
453 <para>The
<literal>[MACVLAN]
</literal> section only applies for
454 netdevs of kind
<literal>macvlan
</literal>, and accepts the
455 following key:
</para>
457 <variablelist class='network-directives'
>
459 <term><varname>Mode=
</varname></term>
461 <para>The MACVLAN mode to use. The supported options are
462 <literal>private
</literal>,
463 <literal>vepa
</literal>,
464 <literal>bridge
</literal>, and
465 <literal>passthru
</literal>.
474 <title>[MACVTAP] Section Options
</title>
476 <para>The
<literal>[MACVTAP]
</literal> section applies for
477 netdevs of kind
<literal>macvtap
</literal> and accepts the
478 same key as
<literal>[MACVLAN]
</literal>.
</para>
483 <title>[IPVLAN] Section Options
</title>
485 <para>The
<literal>[IPVLAN]
</literal> section only applies for
486 netdevs of kind
<literal>ipvlan
</literal>, and accepts the
487 following key:
</para>
489 <variablelist class='network-directives'
>
491 <term><varname>Mode=
</varname></term>
493 <para>The IPVLAN mode to use. The supported options are
494 <literal>L2
</literal>,
<literal>L3
</literal> and
<literal>L3S
</literal>.
499 <term><varname>Flags=
</varname></term>
501 <para>The IPVLAN flags to use. The supported options are
502 <literal>bridge
</literal>,
<literal>private
</literal> and
<literal>vepa
</literal>.
511 <title>[VXLAN] Section Options
</title>
512 <para>The
<literal>[VXLAN]
</literal> section only applies for
513 netdevs of kind
<literal>vxlan
</literal>, and accepts the
514 following keys:
</para>
516 <variablelist class='network-directives'
>
518 <term><varname>Id=
</varname></term>
520 <para>The VXLAN ID to use.
</para>
524 <term><varname>Remote=
</varname></term>
526 <para>Configures destination IP address.
</para>
530 <term><varname>Local=
</varname></term>
532 <para>Configures local IP address.
</para>
536 <term><varname>TOS=
</varname></term>
538 <para>The Type Of Service byte value for a vxlan interface.
</para>
542 <term><varname>TTL=
</varname></term>
544 <para>A fixed Time To Live N on Virtual eXtensible Local
545 Area Network packets. N is a number in the range
1–
255.
0
546 is a special value meaning that packets inherit the TTL
551 <term><varname>MacLearning=
</varname></term>
553 <para>A boolean. When true, enables dynamic MAC learning
554 to discover remote MAC addresses.
</para>
558 <term><varname>FDBAgeingSec=
</varname></term>
560 <para>The lifetime of Forwarding Database entry learnt by
561 the kernel, in seconds.
</para>
565 <term><varname>MaximumFDBEntries=
</varname></term>
567 <para>Configures maximum number of FDB entries.
</para>
571 <term><varname>ReduceARPProxy=
</varname></term>
573 <para>A boolean. When true, bridge-connected VXLAN tunnel
574 endpoint answers ARP requests from the local bridge on behalf
575 of remote Distributed Overlay Virtual Ethernet
576 <ulink url=
"https://en.wikipedia.org/wiki/Distributed_Overlay_Virtual_Ethernet">
577 (DVOE)
</ulink> clients. Defaults to false.
</para>
581 <term><varname>L2MissNotification=
</varname></term>
583 <para>A boolean. When true, enables netlink LLADDR miss
584 notifications.
</para>
588 <term><varname>L3MissNotification=
</varname></term>
590 <para>A boolean. When true, enables netlink IP address miss
591 notifications.
</para>
595 <term><varname>RouteShortCircuit=
</varname></term>
597 <para>A boolean. When true, route short circuiting is turned
602 <term><varname>UDPChecksum=
</varname></term>
604 <para>A boolean. When true, transmitting UDP checksums when doing VXLAN/IPv4 is turned on.
</para>
608 <term><varname>UDP6ZeroChecksumTx=
</varname></term>
610 <para>A boolean. When true, sending zero checksums in VXLAN/IPv6 is turned on.
</para>
614 <term><varname>UDP6ZeroChecksumRx=
</varname></term>
616 <para>A boolean. When true, receiving zero checksums in VXLAN/IPv6 is turned on.
</para>
620 <term><varname>RemoteChecksumTx=
</varname></term>
622 <para>A boolean. When true, remote transmit checksum offload of VXLAN is turned on.
</para>
626 <term><varname>RemoteChecksumRx=
</varname></term>
628 <para>A boolean. When true, remote receive checksum offload in VXLAN is turned on.
</para>
632 <term><varname>GroupPolicyExtension=
</varname></term>
634 <para>A boolean. When true, it enables Group Policy VXLAN extension security label mechanism
635 across network peers based on VXLAN. For details about the Group Policy VXLAN, see the
636 <ulink url=
"https://tools.ietf.org/html/draft-smith-vxlan-group-policy">
637 VXLAN Group Policy
</ulink> document. Defaults to false.
</para>
641 <term><varname>DestinationPort=
</varname></term>
643 <para>Configures the default destination UDP port on a per-device basis.
644 If destination port is not specified then Linux kernel default will be used.
645 Set destination port
4789 to get the IANA assigned value. If not set or if the
646 destination port is assigned the empty string the default port of
4789 is used.
</para>
650 <term><varname>PortRange=
</varname></term>
652 <para>Configures VXLAN port range. VXLAN bases source
653 UDP port based on flow to help the receiver to be able
654 to load balance based on outer header flow. It
655 restricts the port range to the normal UDP local
656 ports, and allows overriding via configuration.
</para>
660 <term><varname>FlowLabel=
</varname></term>
662 <para>Specifies the flow label to use in outgoing packets.
663 The valid range is
0-
1048575.
670 <title>[GENEVE] Section Options
</title>
671 <para>The
<literal>[GENEVE]
</literal> section only applies for
672 netdevs of kind
<literal>geneve
</literal>, and accepts the
673 following keys:
</para>
675 <variablelist class='network-directives'
>
677 <term><varname>Id=
</varname></term>
679 <para>Specifies the Virtual Network Identifier (VNI) to use. Ranges [
0-
16777215].
</para>
683 <term><varname>Remote=
</varname></term>
685 <para>Specifies the unicast destination IP address to use in outgoing packets.
</para>
689 <term><varname>TOS=
</varname></term>
691 <para>Specifies the TOS value to use in outgoing packets. Ranges [
1-
255].
</para>
695 <term><varname>TTL=
</varname></term>
697 <para>Specifies the TTL value to use in outgoing packets. Ranges [
1-
255].
</para>
701 <term><varname>UDPChecksum=
</varname></term>
703 <para>A boolean. When true, specifies if UDP checksum is calculated for transmitted packets over IPv4.
</para>
707 <term><varname>UDP6ZeroChecksumTx=
</varname></term>
709 <para>A boolean. When true, skip UDP checksum calculation for transmitted packets over IPv6.
</para>
713 <term><varname>UDP6ZeroChecksumRx=
</varname></term>
715 <para>A boolean. When true, allows incoming UDP packets over IPv6 with zero checksum field.
</para>
719 <term><varname>DestinationPort=
</varname></term>
721 <para>Specifies destination port. Defaults to
6081. If not set or assigned the empty string, the default
722 port of
6081 is used.
</para>
726 <term><varname>FlowLabel=
</varname></term>
728 <para>Specifies the flow label to use in outgoing packets.
</para>
734 <title>[Tunnel] Section Options
</title>
736 <para>The
<literal>[Tunnel]
</literal> section only applies for
738 <literal>ipip
</literal>,
739 <literal>sit
</literal>,
740 <literal>gre
</literal>,
741 <literal>gretap
</literal>,
742 <literal>ip6gre
</literal>,
743 <literal>ip6gretap
</literal>,
744 <literal>vti
</literal>,
745 <literal>vti6
</literal>, and
746 <literal>ip6tnl
</literal> and accepts
747 the following keys:
</para>
749 <variablelist class='network-directives'
>
751 <term><varname>Local=
</varname></term>
753 <para>A static local address for tunneled packets. It must
754 be an address on another interface of this host.
</para>
758 <term><varname>Remote=
</varname></term>
760 <para>The remote endpoint of the tunnel.
</para>
764 <term><varname>TOS=
</varname></term>
766 <para>The Type Of Service byte value for a tunnel interface.
767 For details about the TOS, see the
768 <ulink url=
"http://tools.ietf.org/html/rfc1349"> Type of
769 Service in the Internet Protocol Suite
</ulink> document.
774 <term><varname>TTL=
</varname></term>
776 <para>A fixed Time To Live N on tunneled packets. N is a
777 number in the range
1–
255.
0 is a special value meaning that
778 packets inherit the TTL value. The default value for IPv4
779 tunnels is: inherit. The default value for IPv6 tunnels is
784 <term><varname>DiscoverPathMTU=
</varname></term>
786 <para>A boolean. When true, enables Path MTU Discovery on
791 <term><varname>IPv6FlowLabel=
</varname></term>
793 <para>Configures the
20-bit flow label (see
<ulink url=
"https://tools.ietf.org/html/rfc6437">
794 RFC
6437</ulink>) field in the IPv6 header (see
<ulink url=
"https://tools.ietf.org/html/rfc2460">
795 RFC
2460</ulink>), which is used by a node to label packets of a flow.
796 It is only used for IPv6 tunnels.
797 A flow label of zero is used to indicate packets that have
799 It can be configured to a value in the range
0–
0xFFFFF, or be
800 set to
<literal>inherit
</literal>, in which case the original flowlabel is used.
</para>
804 <term><varname>CopyDSCP=
</varname></term>
806 <para>A boolean. When true, the Differentiated Service Code
807 Point (DSCP) field will be copied to the inner header from
808 outer header during the decapsulation of an IPv6 tunnel
809 packet. DSCP is a field in an IP packet that enables different
810 levels of service to be assigned to network traffic.
811 Defaults to
<literal>no
</literal>.
816 <term><varname>EncapsulationLimit=
</varname></term>
818 <para>The Tunnel Encapsulation Limit option specifies how many additional
819 levels of encapsulation are permitted to be prepended to the packet.
820 For example, a Tunnel Encapsulation Limit option containing a limit
821 value of zero means that a packet carrying that option may not enter
822 another tunnel before exiting the current tunnel.
823 (see
<ulink url=
"https://tools.ietf.org/html/rfc2473#section-4.1.1"> RFC
2473</ulink>).
824 The valid range is
0–
255 and
<literal>none
</literal>. Defaults to
4.
829 <term><varname>Key=
</varname></term>
831 <para>The
<varname>Key=
</varname> parameter specifies the same key to use in
832 both directions (
<varname>InputKey=
</varname> and
<varname>OutputKey=
</varname>).
833 The
<varname>Key=
</varname> is either a number or an IPv4 address-like dotted quad.
834 It is used as mark-configured SAD/SPD entry as part of the lookup key (both in data
835 and control path) in ip xfrm (framework used to implement IPsec protocol).
836 See
<ulink url=
"http://man7.org/linux/man-pages/man8/ip-xfrm.8.html">
837 ip-xfrm — transform configuration
</ulink> for details. It is only used for VTI/VTI6
842 <term><varname>InputKey=
</varname></term>
844 <para>The
<varname>InputKey=
</varname> parameter specifies the key to use for input.
845 The format is same as
<varname>Key=
</varname>. It is only used for VTI/VTI6 tunnels.
</para>
849 <term><varname>OutputKey=
</varname></term>
851 <para>The
<varname>OutputKey=
</varname> parameter specifies the key to use for output.
852 The format is same as
<varname>Key=
</varname>. It is only used for VTI/VTI6 tunnels.
</para>
856 <term><varname>Mode=
</varname></term>
858 <para>An
<literal>ip6tnl
</literal> tunnel can be in one of three
860 <literal>ip6ip6
</literal> for IPv6 over IPv6,
861 <literal>ipip6
</literal> for IPv4 over IPv6 or
862 <literal>any
</literal> for either.
867 <term><varname>Independent=
</varname></term>
869 <para>A boolean. When true tunnel does not require .network file. Created as
"tunnel@NONE".
870 Defaults to
<literal>false
</literal>.
875 <term><varname>AllowLocalRemote=
</varname></term>
877 <para>A boolean. When true allows tunnel traffic on
<varname>ip6tnl
</varname> devices where the remote endpoint is a local host address.
885 <title>[Peer] Section Options
</title>
887 <para>The
<literal>[Peer]
</literal> section only applies for
888 netdevs of kind
<literal>veth
</literal> and accepts the
889 following keys:
</para>
891 <variablelist class='network-directives'
>
893 <term><varname>Name=
</varname></term>
895 <para>The interface name used when creating the netdev.
896 This option is compulsory.
</para>
900 <term><varname>MACAddress=
</varname></term>
902 <para>The peer MACAddress, if not set, it is generated in
903 the same way as the MAC address of the main
910 <title>[VXCAN] Section Options
</title>
911 <para>The
<literal>[VXCAN]
</literal> section only applies for
912 netdevs of kind
<literal>vxcan
</literal> and accepts the
913 following key:
</para>
915 <variablelist class='network-directives'
>
917 <term><varname>Peer=
</varname></term>
919 <para>The peer interface name used when creating the netdev.
920 This option is compulsory.
</para>
926 <title>[Tun] Section Options
</title>
928 <para>The
<literal>[Tun]
</literal> section only applies for
929 netdevs of kind
<literal>tun
</literal>, and accepts the following
932 <variablelist class='network-directives'
>
934 <term><varname>OneQueue=
</varname></term>
935 <listitem><para>Takes a boolean argument. Configures whether
936 all packets are queued at the device (enabled), or a fixed
937 number of packets are queued at the device and the rest at the
938 <literal>qdisc
</literal>. Defaults to
939 <literal>no
</literal>.
</para>
943 <term><varname>MultiQueue=
</varname></term>
944 <listitem><para>Takes a boolean argument. Configures whether
945 to use multiple file descriptors (queues) to parallelize
946 packets sending and receiving. Defaults to
947 <literal>no
</literal>.
</para>
951 <term><varname>PacketInfo=
</varname></term>
952 <listitem><para>Takes a boolean argument. Configures whether
953 packets should be prepended with four extra bytes (two flag
954 bytes and two protocol bytes). If disabled, it indicates that
955 the packets will be pure IP packets. Defaults to
956 <literal>no
</literal>.
</para>
960 <term><varname>VNetHeader=
</varname></term>
961 <listitem><para>Takes a boolean argument. Configures
962 IFF_VNET_HDR flag for a tap device. It allows sending
963 and receiving larger Generic Segmentation Offload (GSO)
964 packets. This may increase throughput significantly.
966 <literal>no
</literal>.
</para>
970 <term><varname>User=
</varname></term>
971 <listitem><para>User to grant access to the
972 <filename>/dev/net/tun
</filename> device.
</para>
976 <term><varname>Group=
</varname></term>
977 <listitem><para>Group to grant access to the
978 <filename>/dev/net/tun
</filename> device.
</para>
987 <title>[Tap] Section Options
</title>
989 <para>The
<literal>[Tap]
</literal> section only applies for
990 netdevs of kind
<literal>tap
</literal>, and accepts the same keys
991 as the
<literal>[Tun]
</literal> section.
</para>
995 <title>[WireGuard] Section Options
</title>
997 <para>The
<literal>[WireGuard]
</literal> section accepts the following
1000 <variablelist class='network-directives'
>
1002 <term><varname>PrivateKey=
</varname></term>
1004 <para>The Base64 encoded private key for the interface. It can be
1005 generated using the
<command>wg genkey
</command> command
1006 (see
<citerefentry project=
"wireguard"><refentrytitle>wg
</refentrytitle><manvolnum>8</manvolnum></citerefentry>).
1007 This option is mandatory to use WireGuard.
1008 Note that because this information is secret, you may want to set
1009 the permissions of the .netdev file to be owned by
<literal>root:systemd-network
</literal>
1010 with a
<literal>0640</literal> file mode.
</para>
1014 <term><varname>ListenPort=
</varname></term>
1016 <para>Sets UDP port for listening. Takes either value between
1 and
65535
1017 or
<literal>auto
</literal>. If
<literal>auto
</literal> is specified,
1018 the port is automatically generated based on interface name.
1019 Defaults to
<literal>auto
</literal>.
</para>
1023 <term><varname>FwMark=
</varname></term>
1025 <para>Sets a firewall mark on outgoing WireGuard packets from this interface.
</para>
1032 <title>[WireGuardPeer] Section Options
</title>
1034 <para>The
<literal>[WireGuardPeer]
</literal> section accepts the following
1037 <variablelist class='network-directives'
>
1039 <term><varname>PublicKey=
</varname></term>
1041 <para>Sets a Base64 encoded public key calculated by
<command>wg pubkey
</command>
1042 (see
<citerefentry project=
"wireguard"><refentrytitle>wg
</refentrytitle><manvolnum>8</manvolnum></citerefentry>)
1043 from a private key, and usually transmitted out of band to the
1044 author of the configuration file. This option is mandatory for this
1049 <term><varname>PresharedKey=
</varname></term>
1051 <para>Optional preshared key for the interface. It can be generated
1052 by the
<command>wg genpsk
</command> command. This option adds an
1053 additional layer of symmetric-key cryptography to be mixed into the
1054 already existing public-key cryptography, for post-quantum
1056 Note that because this information is secret, you may want to set
1057 the permissions of the .netdev file to be owned by
<literal>root:systemd-networkd
</literal>
1058 with a
<literal>0640</literal> file mode.
</para>
1062 <term><varname>AllowedIPs=
</varname></term>
1064 <para>Sets a comma-separated list of IP (v4 or v6) addresses with CIDR masks
1065 from which this peer is allowed to send incoming traffic and to
1066 which outgoing traffic for this peer is directed. The catch-all
1067 0.0.0.0/
0 may be specified for matching all IPv4 addresses, and
1068 ::/
0 may be specified for matching all IPv6 addresses.
</para>
1072 <term><varname>Endpoint=
</varname></term>
1074 <para>Sets an endpoint IP address or hostname, followed by a colon, and then
1075 a port number. This endpoint will be updated automatically once to
1076 the most recent source IP address and port of correctly
1077 authenticated packets from the peer at configuration time.
</para>
1081 <term><varname>PersistentKeepalive=
</varname></term>
1083 <para>Sets a seconds interval, between
1 and
65535 inclusive, of how often
1084 to send an authenticated empty packet to the peer for the purpose
1085 of keeping a stateful firewall or NAT mapping valid persistently.
1086 For example, if the interface very rarely sends traffic, but it
1087 might at anytime receive traffic from a peer, and it is behind NAT,
1088 the interface might benefit from having a persistent keepalive
1089 interval of
25 seconds. If set to
0 or
"off", this option is
1090 disabled. By default or when unspecified, this option is off.
1091 Most users will not need this.
</para>
1098 <title>[Bond] Section Options
</title>
1100 <para>The
<literal>[Bond]
</literal> section accepts the following
1103 <variablelist class='network-directives'
>
1105 <term><varname>Mode=
</varname></term>
1107 <para>Specifies one of the bonding policies. The default is
1108 <literal>balance-rr
</literal> (round robin). Possible values are
1109 <literal>balance-rr
</literal>,
1110 <literal>active-backup
</literal>,
1111 <literal>balance-xor
</literal>,
1112 <literal>broadcast
</literal>,
1113 <literal>802.3ad
</literal>,
1114 <literal>balance-tlb
</literal>, and
1115 <literal>balance-alb
</literal>.
1121 <term><varname>TransmitHashPolicy=
</varname></term>
1123 <para>Selects the transmit hash policy to use for slave
1124 selection in balance-xor,
802.3ad, and tlb modes. Possible
1126 <literal>layer2
</literal>,
1127 <literal>layer3+
4</literal>,
1128 <literal>layer2+
3</literal>,
1129 <literal>encap2+
3</literal>, and
1130 <literal>encap3+
4</literal>.
1136 <term><varname>LACPTransmitRate=
</varname></term>
1138 <para>Specifies the rate with which link partner transmits
1139 Link Aggregation Control Protocol Data Unit packets in
1140 802.3ad mode. Possible values are
<literal>slow
</literal>,
1141 which requests partner to transmit LACPDUs every
30 seconds,
1142 and
<literal>fast
</literal>, which requests partner to
1143 transmit LACPDUs every second. The default value is
1144 <literal>slow
</literal>.
</para>
1149 <term><varname>MIIMonitorSec=
</varname></term>
1151 <para>Specifies the frequency that Media Independent
1152 Interface link monitoring will occur. A value of zero
1153 disables MII link monitoring. This value is rounded down to
1154 the nearest millisecond. The default value is
0.
</para>
1159 <term><varname>UpDelaySec=
</varname></term>
1161 <para>Specifies the delay before a link is enabled after a
1162 link up status has been detected. This value is rounded down
1163 to a multiple of MIIMonitorSec. The default value is
1169 <term><varname>DownDelaySec=
</varname></term>
1171 <para>Specifies the delay before a link is disabled after a
1172 link down status has been detected. This value is rounded
1173 down to a multiple of MIIMonitorSec. The default value is
1179 <term><varname>LearnPacketIntervalSec=
</varname></term>
1181 <para>Specifies the number of seconds between instances where the bonding
1182 driver sends learning packets to each slave peer switch.
1183 The valid range is
1–
0x7fffffff; the default value is
1. This option
1184 has an effect only for the balance-tlb and balance-alb modes.
</para>
1189 <term><varname>AdSelect=
</varname></term>
1191 <para>Specifies the
802.3ad aggregation selection logic to use. Possible values are
1192 <literal>stable
</literal>,
1193 <literal>bandwidth
</literal> and
1194 <literal>count
</literal>.
1200 <term><varname>FailOverMACPolicy=
</varname></term>
1202 <para>Specifies whether the active-backup mode should set all slaves to
1203 the same MAC address at the time of enslavement or, when enabled, to perform special handling of the
1204 bond's MAC address in accordance with the selected policy. The default policy is none.
1206 <literal>none
</literal>,
1207 <literal>active
</literal> and
1208 <literal>follow
</literal>.
1214 <term><varname>ARPValidate=
</varname></term>
1216 <para>Specifies whether or not ARP probes and replies should be
1217 validated in any mode that supports ARP monitoring, or whether
1218 non-ARP traffic should be filtered (disregarded) for link
1219 monitoring purposes. Possible values are
1220 <literal>none
</literal>,
1221 <literal>active
</literal>,
1222 <literal>backup
</literal> and
1223 <literal>all
</literal>.
1229 <term><varname>ARPIntervalSec=
</varname></term>
1231 <para>Specifies the ARP link monitoring frequency in milliseconds.
1232 A value of
0 disables ARP monitoring. The default value is
0.
1238 <term><varname>ARPIPTargets=
</varname></term>
1240 <para>Specifies the IP addresses to use as ARP monitoring peers when
1241 ARPIntervalSec is greater than
0. These are the targets of the ARP request
1242 sent to determine the health of the link to the targets.
1243 Specify these values in IPv4 dotted decimal format. At least one IP
1244 address must be given for ARP monitoring to function. The
1245 maximum number of targets that can be specified is
16. The
1246 default value is no IP addresses.
1252 <term><varname>ARPAllTargets=
</varname></term>
1254 <para>Specifies the quantity of ARPIPTargets that must be reachable
1255 in order for the ARP monitor to consider a slave as being up.
1256 This option affects only active-backup mode for slaves with
1257 ARPValidate enabled. Possible values are
1258 <literal>any
</literal> and
1259 <literal>all
</literal>.
1265 <term><varname>PrimaryReselectPolicy=
</varname></term>
1267 <para>Specifies the reselection policy for the primary slave. This
1268 affects how the primary slave is chosen to become the active slave
1269 when failure of the active slave or recovery of the primary slave
1270 occurs. This option is designed to prevent flip-flopping between
1271 the primary slave and other slaves. Possible values are
1272 <literal>always
</literal>,
1273 <literal>better
</literal> and
1274 <literal>failure
</literal>.
1280 <term><varname>ResendIGMP=
</varname></term>
1282 <para>Specifies the number of IGMP membership reports to be issued after
1283 a failover event. One membership report is issued immediately after
1284 the failover, subsequent packets are sent in each
200ms interval.
1285 The valid range is
0–
255. Defaults to
1. A value of
0
1286 prevents the IGMP membership report from being issued in response
1287 to the failover event.
1293 <term><varname>PacketsPerSlave=
</varname></term>
1295 <para>Specify the number of packets to transmit through a slave before
1296 moving to the next one. When set to
0, then a slave is chosen at
1297 random. The valid range is
0–
65535. Defaults to
1. This option
1298 only has effect when in balance-rr mode.
1304 <term><varname>GratuitousARP=
</varname></term>
1306 <para>Specify the number of peer notifications (gratuitous ARPs and
1307 unsolicited IPv6 Neighbor Advertisements) to be issued after a
1308 failover event. As soon as the link is up on the new slave,
1309 a peer notification is sent on the bonding device and each
1310 VLAN sub-device. This is repeated at each link monitor interval
1311 (ARPIntervalSec or MIIMonitorSec, whichever is active) if the number is
1312 greater than
1. The valid range is
0–
255. The default value is
1.
1313 These options affect only the active-backup mode.
1319 <term><varname>AllSlavesActive=
</varname></term>
1321 <para>A boolean. Specifies that duplicate frames (received on inactive ports)
1322 should be dropped when false, or delivered when true. Normally, bonding will drop
1323 duplicate frames (received on inactive ports), which is desirable for
1324 most users. But there are some times it is nice to allow duplicate
1325 frames to be delivered. The default value is false (drop duplicate frames
1326 received on inactive ports).
1332 <term><varname>MinLinks=
</varname></term>
1334 <para>Specifies the minimum number of links that must be active before
1335 asserting carrier. The default value is
0.
1341 <para>For more detail information see
1342 <ulink url=
"https://www.kernel.org/doc/Documentation/networking/bonding.txt">
1343 Linux Ethernet Bonding Driver HOWTO
</ulink></para>
1348 <title>Examples
</title>
1350 <title>/etc/systemd/network/
25-bridge.netdev
</title>
1352 <programlisting>[NetDev]
1354 Kind=bridge
</programlisting>
1358 <title>/etc/systemd/network/
25-vlan1.netdev
</title>
1360 <programlisting>[Match]
1368 Id=
1</programlisting>
1371 <title>/etc/systemd/network/
25-ipip.netdev
</title>
1372 <programlisting>[NetDev]
1378 Local=
192.168.223.238
1379 Remote=
192.169.224.239
1380 TTL=
64</programlisting>
1383 <title>/etc/systemd/network/
25-tap.netdev
</title>
1384 <programlisting>[NetDev]
1390 PacketInfo=true
</programlisting> </example>
1393 <title>/etc/systemd/network/
25-sit.netdev
</title>
1394 <programlisting>[NetDev]
1401 Remote=
10.65.223.239</programlisting>
1405 <title>/etc/systemd/network/
25-gre.netdev
</title>
1406 <programlisting>[NetDev]
1413 Remote=
10.65.223.239</programlisting>
1417 <title>/etc/systemd/network/
25-vti.netdev
</title>
1419 <programlisting>[NetDev]
1426 Remote=
10.65.223.239</programlisting>
1430 <title>/etc/systemd/network/
25-veth.netdev
</title>
1431 <programlisting>[NetDev]
1436 Name=veth-peer
</programlisting>
1440 <title>/etc/systemd/network/
25-bond.netdev
</title>
1441 <programlisting>[NetDev]
1447 TransmitHashPolicy=layer3+
4
1449 LACPTransmitRate=fast
1454 <title>/etc/systemd/network/
25-dummy.netdev
</title>
1455 <programlisting>[NetDev]
1458 MACAddress=
12:
34:
56:
78:
9a:bc
</programlisting>
1461 <title>/etc/systemd/network/
25-vrf.netdev
</title>
1462 <para>Create a VRF interface with table
42.
</para>
1463 <programlisting>[NetDev]
1468 Table=
42</programlisting>
1472 <title>/etc/systemd/network/
25-macvtap.netdev
</title>
1473 <para>Create a MacVTap device.
</para>
1474 <programlisting>[NetDev]
1480 <title>/etc/systemd/network/
25-wireguard.netdev
</title>
1481 <programlisting>[NetDev]
1486 PrivateKey=EEGlnEPYJV//kbvvIqxKkQwOiS+UENyPncC4bF46ong=
1490 PublicKey=RDf+LSpeEre7YEIKaxg+wbpsNV7du+ktR99uBEtIiCA=
1491 AllowedIPs=fd31:bf08:
57cb::/
48,
192.168.26.0/
24
1492 Endpoint=wireguard.example.com:
51820</programlisting>
1496 <title>See Also
</title>
1498 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1499 <citerefentry><refentrytitle>systemd-networkd
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1500 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1501 <citerefentry><refentrytitle>systemd.network
</refentrytitle><manvolnum>5</manvolnum></citerefentry>