2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
6 <refentry id=
"systemd.network" conditional='ENABLE_NETWORKD'
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>systemd.network
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>systemd.network
</refentrytitle>
16 <manvolnum>5</manvolnum>
20 <refname>systemd.network
</refname>
21 <refpurpose>Network configuration
</refpurpose>
25 <para><filename><replaceable>network
</replaceable>.network
</filename></para>
29 <title>Description
</title>
31 <para>A plain ini-style text file that encodes network configuration for matching network interfaces,
33 <citerefentry><refentrytitle>systemd-networkd
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
34 See
<citerefentry><refentrytitle>systemd.syntax
</refentrytitle><manvolnum>7</manvolnum></citerefentry>
35 for a general description of the syntax.
</para>
37 <para>The main network file must have the extension
<filename>.network
</filename>; other
38 extensions are ignored. Networks are applied to links whenever the links appear.
</para>
40 <para>The
<filename>.network
</filename> files are read from the files located in the system network
41 directories
<filename>/usr/lib/systemd/network
</filename> and
42 <filename>/usr/local/lib/systemd/network
</filename>, the volatile runtime network directory
43 <filename>/run/systemd/network
</filename> and the local administration network directory
44 <filename>/etc/systemd/network
</filename>. All configuration files are collectively sorted and processed
45 in lexical order, regardless of the directories in which they live. However, files with identical
46 filenames replace each other. Files in
<filename>/etc/
</filename> have the highest priority, files in
47 <filename>/run/
</filename> take precedence over files with the same name under
48 <filename>/usr/
</filename>. This can be used to override a system-supplied configuration file with a local
49 file if needed. As a special case, an empty file (file size
0) or symlink with the same name pointing to
50 <filename>/dev/null
</filename> disables the configuration file entirely (it is
"masked").
</para>
52 <para>Along with the network file
<filename>foo.network
</filename>, a
"drop-in" directory
53 <filename>foo.network.d/
</filename> may exist. All files with the suffix
54 <literal>.conf
</literal> from this directory will be parsed after the file itself is
55 parsed. This is useful to alter or add configuration settings, without having to modify the main
56 configuration file. Each drop-in file must have appropriate section headers.
</para>
58 <para>In addition to
<filename>/etc/systemd/network
</filename>, drop-in
<literal>.d
</literal>
59 directories can be placed in
<filename>/usr/lib/systemd/network
</filename> or
60 <filename>/run/systemd/network
</filename> directories. Drop-in files in
61 <filename>/etc/
</filename> take precedence over those in
<filename>/run/
</filename> which in turn
62 take precedence over those in
<filename>/usr/lib/
</filename>. Drop-in files under any of these
63 directories take precedence over the main network file wherever located.
</para>
65 <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6
66 nor IPv6LL enabled, shall be considered to have no IPv6 support. IPv6 will be automatically
67 disabled for that interface by writing
"1" to
68 <filename>/proc/sys/net/ipv6/conf/
<replaceable>ifname
</replaceable>/disable_ipv6
</filename>.
73 <title>[Match] Section Options
</title>
75 <para>The network file contains a [Match] section, which determines if a given network file may be
76 applied to a given device; and a [Network] section specifying how the device should be configured. The
77 first (in lexical order) of the network files that matches a given device is applied, all later files
78 are ignored, even if they match as well.
</para>
80 <para>A network file is said to match a network interface if all matches specified by the [Match]
81 section are satisfied. When a network file does not contain valid settings in [Match] section, then the
82 file will match all interfaces and
<command>systemd-networkd
</command> warns about that. Hint: to avoid
83 the warning and to make it clear that all interfaces shall be matched, add the following:
84 <programlisting>Name=*
</programlisting> The following keys are accepted:
</para>
86 <variablelist class='network-directives'
>
87 <xi:include href=
"systemd.link.xml" xpointer=
"mac-address" />
88 <xi:include href=
"systemd.link.xml" xpointer=
"permanent-mac-address" />
89 <xi:include href=
"systemd.link.xml" xpointer=
"path" />
90 <xi:include href=
"systemd.link.xml" xpointer=
"driver" />
91 <xi:include href=
"systemd.link.xml" xpointer=
"type" />
92 <xi:include href=
"systemd.link.xml" xpointer=
"property" />
95 <term><varname>Name=
</varname></term>
97 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
98 by the udev property
<literal>INTERFACE
</literal>, or device's alternative names. If the
99 list is prefixed with a
"!", the test is inverted.
</para>
104 <term><varname>WLANInterfaceType=
</varname></term>
106 <para>A whitespace-separated list of wireless network type. Supported values are
107 <literal>ad-hoc
</literal>,
<literal>station
</literal>,
<literal>ap
</literal>,
108 <literal>ap-vlan
</literal>,
<literal>wds
</literal>,
<literal>monitor
</literal>,
109 <literal>mesh-point
</literal>,
<literal>p2p-client
</literal>,
<literal>p2p-go
</literal>,
110 <literal>p2p-device
</literal>,
<literal>ocb
</literal>, and
<literal>nan
</literal>. If the
111 list is prefixed with a
"!", the test is inverted.
117 <term><varname>SSID=
</varname></term>
119 <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
120 connected wireless LAN. If the list is prefixed with a
"!", the test is inverted.
126 <term><varname>BSSID=
</varname></term>
128 <para>A whitespace-separated list of hardware address of the currently connected wireless
129 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
130 <varname>MACAddress=
</varname>. This option may appear more than once, in which case the
131 lists are merged. If the empty string is assigned to this option, the list is reset.
</para>
135 <xi:include href=
"systemd.link.xml" xpointer=
"host" />
136 <xi:include href=
"systemd.link.xml" xpointer=
"virtualization" />
137 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-command-line" />
138 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-version" />
139 <xi:include href=
"systemd.link.xml" xpointer=
"architecture" />
145 <title>[Link] Section Options
</title>
147 <para> The [Link] section accepts the following keys:
</para>
149 <variablelist class='network-directives'
>
151 <term><varname>MACAddress=
</varname></term>
153 <para>The hardware address to set for the device.
</para>
157 <term><varname>MTUBytes=
</varname></term>
159 <para>The maximum transmission unit in bytes to set for the
160 device. The usual suffixes K, M, G, are supported and are
161 understood to the base of
1024.
</para>
162 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
163 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
167 <term><varname>ARP=
</varname></term>
169 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
170 for this interface is enabled. When unset, the kernel's default will be used.
</para>
171 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
172 interfaces atop a single lower-level physical interface, which will then only serve as a
173 link/
"bridge" device aggregating traffic to the same physical link and not participate in
174 the network otherwise. Defaults to unset.
</para>
178 <term><varname>Multicast=
</varname></term>
180 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults to unset.
</para>
184 <term><varname>AllMulticast=
</varname></term>
186 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the network.
187 This happens when multicast routing is enabled. Defaults to unset.
</para>
191 <term><varname>Promiscuous=
</varname></term>
193 <para>Takes a boolean. If set to true, promiscuous mode of the interface is enabled.
194 Defaults to unset.
</para>
198 <term><varname>Unmanaged=
</varname></term>
200 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are
201 made to bring up or configure matching links, equivalent to
202 when there are no matching network files. Defaults to
203 <literal>no
</literal>.
</para>
204 <para>This is useful for preventing later matching network
205 files from interfering with certain interfaces that are fully
206 controlled by other applications.
</para>
210 <term><varname>Group=
</varname></term>
212 <para>Link groups are similar to port ranges found in managed switches.
213 When network interfaces are added to a numbered group, operations on
214 all the interfaces from that group can be performed at once. An unsigned
215 integer in the range
0…
4294967294. Defaults to unset.
</para>
219 <term><varname>RequiredForOnline=
</varname></term>
221 <para>Takes a boolean or a minimum operational state and an optional maximum operational state.
222 Please see
<citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
223 for possible operational states. When
<literal>yes
</literal>, the network is deemed required when
224 determining whether the system is online when running
225 <command>systemd-networkd-wait-online
</command>. When
<literal>no
</literal>, the network is ignored
226 when checking for online state. When a minimum operational state and an optional maximum operational
227 state are set,
<literal>yes
</literal> is implied, and this controls the minimum and maximum
228 operational state required for the network interface to be considered online.
229 Defaults to
<literal>yes
</literal>.
</para>
231 <para>The network will be brought up normally in all cases, but in
232 the event that there is no address being assigned by DHCP or the
233 cable is not plugged in, the link will simply remain offline and be
234 skipped automatically by
<command>systemd-networkd-wait-online
</command>
235 if
<literal>RequiredForOnline=no
</literal>.
</para>
239 <term><varname>ActivationPolicy=
</varname></term>
241 <para>Specifies the policy for
<command>systemd-networkd
</command> managing the link
242 administrative state. Specifically, this controls how
<command>systemd-networkd
</command>
243 changes the network device's
<literal>IFF_UP
</literal> flag, which is sometimes
244 controlled by system administrators by running e.g.,
<command>ip set dev eth0 up
</command>
245 or
<command>ip set dev eth0 down
</command>, and can also be changed with
246 <command>networkctl up eth0
</command> or
<command>networkctl down eth0
</command>.
</para>
248 <para>Takes one of
<literal>up
</literal>,
<literal>always-up
</literal>,
249 <literal>manual
</literal>,
<literal>always-down
</literal>,
<literal>down
</literal>,
250 or
<literal>bound
</literal>. When
<literal>manual
</literal>,
<command>systemd-networkd
</command>
251 will not change the link's admin state automatically; the system administrator must bring the
252 interface up or down manually, as desired. When
<literal>up
</literal> (the default) or
253 <literal>always-up
</literal>, or
<literal>down
</literal> or
<literal>always-down
</literal>,
254 <command>systemd-networkd
</command> will set the link up or down, respectively,
255 when the interface is (re)configured. When
<literal>always-up
</literal> or
256 <literal>always-down
</literal>,
<command>systemd-networkd
</command> will set the link up
257 or down, respectively, any time
<command>systemd-networkd
</command> detects a change in
258 the administrative state. When
<varname>BindCarrier=
</varname> is also set, this is
259 automatically set to
<literal>bound
</literal> and any other value is ignored.
</para>
261 <para>The administrative state is not the same as the carrier state, so using
262 <literal>always-up
</literal> does not mean the link will never lose carrier. The link
263 carrier depends on both the administrative state as well as the network device's physical
264 connection. However, to avoid reconfiguration failures, when using
<literal>always-up
</literal>,
265 <varname>IgnoreCarrierLoss=
</varname> is forced to true.
</para>
272 <title>[SR-IOV] Section Options
</title>
273 <para>The [SR-IOV] section accepts the following keys. Specify several [SR-IOV] sections to configure
274 several SR-IOVs. SR-IOV provides the ability to partition a single physical PCI resource into virtual
275 PCI functions which can then be injected into a VM. In the case of network VFs, SR-IOV improves
276 north-south network performance (that is, traffic with endpoints outside the host machine) by allowing
277 traffic to bypass the host machine’s network stack.
</para>
279 <variablelist class='network-directives'
>
281 <term><varname>VirtualFunction=
</varname></term>
283 <para>Specifies a Virtual Function (VF), lightweight PCIe function designed solely to move data
284 in and out. Takes an unsigned integer in the range
0…
2147483646. This option is compulsory.
</para>
289 <term><varname>VLANId=
</varname></term>
291 <para>Specifies VLAN ID of the virtual function. Takes an unsigned integer in the range
1…
4095.
</para>
296 <term><varname>QualityOfService=
</varname></term>
298 <para>Specifies quality of service of the virtual function. Takes an unsigned integer in the range
1…
4294967294.
</para>
303 <term><varname>VLANProtocol=
</varname></term>
305 <para>Specifies VLAN protocol of the virtual function. Takes
<literal>802.1Q
</literal> or
306 <literal>802.1ad
</literal>.
</para>
311 <term><varname>MACSpoofCheck=
</varname></term>
313 <para>Takes a boolean. Controls the MAC spoof checking. When unset, the kernel's default will be used.
</para>
318 <term><varname>QueryReceiveSideScaling=
</varname></term>
320 <para>Takes a boolean. Toggle the ability of querying the receive side scaling (RSS)
321 configuration of the virtual function (VF). The VF RSS information like RSS hash key may be
322 considered sensitive on some devices where this information is shared between VF and the
323 physical function (PF). When unset, the kernel's default will be used.
</para>
328 <term><varname>Trust=
</varname></term>
330 <para>Takes a boolean. Allows to set trust mode of the virtual function (VF). When set, VF
331 users can set a specific feature which may impact security and/or performance. When unset,
332 the kernel's default will be used.
</para>
337 <term><varname>LinkState=
</varname></term>
339 <para>Allows to set the link state of the virtual function (VF). Takes a boolean or a
340 special value
<literal>auto
</literal>. Setting to
<literal>auto
</literal> means a
341 reflection of the physical function (PF) link state,
<literal>yes
</literal> lets the VF to
342 communicate with other VFs on this host even if the PF link state is down,
343 <literal>no
</literal> causes the hardware to drop any packets sent by the VF. When unset,
344 the kernel's default will be used.
</para>
349 <term><varname>MACAddress=
</varname></term>
351 <para>Specifies the MAC address for the virtual function.
</para>
358 <title>[Network] Section Options
</title>
360 <para>The [Network] section accepts the following keys:
</para>
362 <variablelist class='network-directives'
>
364 <term><varname>Description=
</varname></term>
366 <para>A description of the device. This is only used for
367 presentation purposes.
</para>
371 <term><varname>DHCP=
</varname></term>
373 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
374 <literal>yes
</literal>,
<literal>no
</literal>,
375 <literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults
376 to
<literal>no
</literal>.
</para>
378 <para>Note that DHCPv6 will by default be triggered by Router
379 Advertisement, if that is enabled, regardless of this parameter.
380 By enabling DHCPv6 support explicitly, the DHCPv6 client will
381 be started regardless of the presence of routers on the link,
382 or what flags the routers pass. See
383 <literal>IPv6AcceptRA=
</literal>.
</para>
385 <para>Furthermore, note that by default the domain name
386 specified through DHCP is not used for name resolution.
387 See option
<option>UseDomains=
</option> below.
</para>
389 <para>See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the DHCP
390 client support.
</para>
394 <term><varname>DHCPServer=
</varname></term>
396 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started. Defaults
397 to
<literal>no
</literal>. Further settings for the DHCP server may be set in the [DHCPServer]
398 section described below.
</para>
402 <term><varname>LinkLocalAddressing=
</varname></term>
404 <para>Enables link-local address autoconfiguration. Accepts
<option>yes
</option>,
405 <option>no
</option>,
<option>ipv4
</option>, and
<option>ipv6
</option>. An IPv6 link-local address
406 is configured when
<option>yes
</option> or
<option>ipv6
</option>. An IPv4 link-local address is
407 configured when
<option>yes
</option> or
<option>ipv4
</option> and when DHCPv4 autoconfiguration
408 has been unsuccessful for some time. (IPv4 link-local address autoconfiguration will usually
409 happen in parallel with repeated attempts to acquire a DHCPv4 lease).
</para>
411 <para>Defaults to
<option>no
</option> when
<varname>Bridge=yes
</varname> is set, and
412 <option>ipv6
</option> otherwise.
</para>
416 <term><varname>IPv6LinkLocalAddressGenerationMode=
</varname></term>
418 <para>Specifies how IPv6 link local address is generated. Takes one of
<literal>eui64
</literal>,
419 <literal>none
</literal>,
<literal>stable-privacy
</literal> and
<literal>random
</literal>.
420 When unset, the kernel's default will be used. Note that if
<varname>LinkLocalAdressing=
</varname>
421 not configured as
<literal>ipv6
</literal> then
<varname>IPv6LinkLocalAddressGenerationMode=
</varname>
426 <term><varname>IPv4LLRoute=
</varname></term>
428 <para>Takes a boolean. If set to true, sets up the route needed for
429 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
435 <term><varname>DefaultRouteOnDevice=
</varname></term>
437 <para>Takes a boolean. If set to true, sets up the default route bound to the interface.
438 Defaults to false. This is useful when creating routes on point-to-point interfaces.
439 This is equivalent to e.g. the following.
440 <programlisting>ip route add default dev veth99
</programlisting></para>
444 <term><varname>IPv6Token=
</varname></term>
446 <para>Specifies an optional address generation mode for the Stateless Address
447 Autoconfiguration (SLAAC). Supported modes are
<literal>prefixstable
</literal> and
448 <literal>static
</literal>.
</para>
450 <para>When the mode is set to
<literal>static
</literal>, an IPv6 address must be
451 specified after a colon (
<literal>:
</literal>), and the lower bits of the supplied
452 address are combined with the upper bits of a prefix received in a Router Advertisement
453 (RA) message to form a complete address. Note that if multiple prefixes are received in an
454 RA message, or in multiple RA messages, addresses will be formed from each of them using
455 the supplied address. This mode implements SLAAC but uses a static interface identifier
456 instead of an identifier generated by using the EUI-
64 algorithm. Because the interface
457 identifier is static, if Duplicate Address Detection detects that the computed address is a
458 duplicate (in use by another node on the link), then this mode will fail to provide an
459 address for that prefix. If an IPv6 address without mode is specified, then
460 <literal>static
</literal> mode is assumed.
</para>
462 <para>When the mode is set to
<literal>prefixstable
</literal> the
463 <ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink> algorithm for generating
464 interface identifiers will be used. This mode can optionally take an IPv6 address separated
465 with a colon (
<literal>:
</literal>). If an IPv6 address is specified, then an interface
466 identifier is generated only when a prefix received in an RA message matches the supplied
469 <para>If no address generation mode is specified (which is the default), or a received
470 prefix does not match any of the addresses provided in
<literal>prefixstable
</literal>
471 mode, then the EUI-
64 algorithm will be used to form an interface identifier for that
472 prefix. This mode is also SLAAC, but with a potentially stable interface identifier which
473 does not directly map to the interface's hardware address.
</para>
475 <para>Note that the
<literal>prefixstable
</literal> algorithm uses both the interface
476 name and MAC address as input to the hash to compute the interface identifier, so if either
477 of those are changed the resulting interface identifier (and address) will change, even if
478 the prefix received in the RA message has not changed.
</para>
480 <para>This setting can be specified multiple times. If an empty string is assigned, then
481 the all previous assignments are cleared.
</para>
484 <programlisting>IPv6Token=::
1a:
2b:
3c:
4d
485 IPv6Token=static:::
1a:
2b:
3c:
4d
486 IPv6Token=prefixstable
487 IPv6Token=prefixstable:
2002:da8:
1::
</programlisting></para>
491 <term><varname>LLMNR=
</varname></term>
493 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
495 url=
"https://tools.ietf.org/html/rfc4795">Link-Local
496 Multicast Name Resolution
</ulink> on the link. When set to
497 <literal>resolve
</literal>, only resolution is enabled,
498 but not host registration and announcement. Defaults to
499 true. This setting is read by
500 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
504 <term><varname>MulticastDNS=
</varname></term>
506 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
508 url=
"https://tools.ietf.org/html/rfc6762">Multicast
509 DNS
</ulink> support on the link. When set to
510 <literal>resolve
</literal>, only resolution is enabled,
511 but not host or service registration and
512 announcement. Defaults to false. This setting is read by
513 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
517 <term><varname>DNSOverTLS=
</varname></term>
519 <para>Takes a boolean or
<literal>opportunistic
</literal>.
522 url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink>
524 When set to
<literal>opportunistic
</literal>, compatibility with
525 non-DNS-over-TLS servers is increased, by automatically
526 turning off DNS-over-TLS servers in this case.
527 This option defines a per-interface setting for
528 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
529 global
<varname>DNSOverTLS=
</varname> option. Defaults to
530 false. This setting is read by
531 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
535 <term><varname>DNSSEC=
</varname></term>
537 <para>Takes a boolean or
<literal>allow-downgrade
</literal>. When true, enables
538 <ulink url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink>
539 DNS validation support on the link. When set to
540 <literal>allow-downgrade
</literal>, compatibility with
541 non-DNSSEC capable networks is increased, by automatically
542 turning off DNSSEC in this case. This option defines a
543 per-interface setting for
544 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
545 global
<varname>DNSSEC=
</varname> option. Defaults to
546 false. This setting is read by
547 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
551 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
552 <listitem><para>A space-separated list of DNSSEC negative
553 trust anchor domains. If specified and DNSSEC is enabled,
554 look-ups done via the interface's DNS server will be subject
555 to the list of negative trust anchors, and not require
556 authentication for the specified domains, or anything below
557 it. Use this to disable DNSSEC authentication for specific
558 private domains, that cannot be proven valid using the
559 Internet DNS hierarchy. Defaults to the empty list. This
561 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
565 <term><varname>LLDP=
</varname></term>
567 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
568 implemented on professional routers and bridges which announces which physical port a system is connected
569 to, as well as other related data. Accepts a boolean or the special value
570 <literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
571 neighbors maintained. If
<literal>routers-only
</literal> is set only LLDP data of various types of routers
572 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
573 others). If false, LLDP reception is disabled. Defaults to
<literal>routers-only
</literal>. Use
574 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
575 collected neighbor data. LLDP is only available on Ethernet links. See
<varname>EmitLLDP=
</varname> below
576 for enabling LLDP packet emission from the local system.
581 <term><varname>EmitLLDP=
</varname></term>
583 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
584 <literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
585 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
586 a short LLDP packet with information about the local system is sent out in regular intervals on the
587 link. The LLDP packet will contain information about the local hostname, the local machine ID (as stored
588 in
<citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
589 local interface name, as well as the pretty hostname of the system (as set in
590 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
591 emission is only available on Ethernet links. Note that this setting passes data suitable for
592 identification of host to the network and should thus not be enabled on untrusted networks, where such
593 identification data should not be made available. Use this option to permit other systems to identify on
594 which interfaces they are connected to this system. The three special values control propagation of the
595 LLDP packets. The
<literal>nearest-bridge
</literal> setting permits propagation only to the nearest
596 connected bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays, but
597 not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until a customer bridge
598 is reached. For details about these concepts, see
<ulink
599 url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>. Note that
600 configuring this setting to true is equivalent to
<literal>nearest-bridge
</literal>, the recommended and
601 most restricted level of propagation. See
<varname>LLDP=
</varname> above for an option to enable LLDP
607 <term><varname>BindCarrier=
</varname></term>
609 <para>A link name or a list of link names. When set, controls the behavior of the current
610 link. When all links in the list are in an operational down state, the current link is brought
611 down. When at least one link has carrier, the current interface is brought up.
</para>
613 <para>This forces
<varname>ActivationPolicy=
</varname> to be set to
<literal>bound
</literal>.
</para>
617 <term><varname>Address=
</varname></term>
619 <para>A static IPv4 or IPv6 address and its prefix length,
620 separated by a
<literal>/
</literal> character. Specify
621 this key more than once to configure several addresses.
622 The format of the address must be as described in
623 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
624 This is a short-hand for an [Address] section only
625 containing an Address key (see below). This option may be
626 specified more than once.
629 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
630 (for IPv6), a new address range of the requested size is automatically allocated from a
631 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
632 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
633 all known network configuration files to avoid address range conflicts. The default system-wide
634 pool consists of
192.168.0.0/
16,
172.16.0.0/
12 and
10.0.0.0/
8 for IPv4, and fd00::/
8 for IPv6.
635 This functionality is useful to manage a large number of dynamically created network interfaces
636 with the same network configuration and automatic address range assignment.
</para>
641 <term><varname>Gateway=
</varname></term>
643 <para>The gateway address, which must be in the format
645 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
646 This is a short-hand for a [Route] section only containing
647 a Gateway key. This option may be specified more than
652 <term><varname>DNS=
</varname></term>
654 <para>A DNS server address, which must be in the format described in
655 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
656 This option may be specified more than once. Each address can optionally take a port number
657 separated with
<literal>:
</literal>, a network interface name or index separated with
658 <literal>%
</literal>, and a Server Name Indication (SNI) separated with
<literal>#
</literal>.
659 When IPv6 address is specified with a port number, then the address must be in the square
660 brackets. That is, the acceptable full formats are
661 <literal>111.222.333.444:
9953%ifname#example.com
</literal> for IPv4 and
662 <literal>[
1111:
2222::
3333]:
9953%ifname#example.com
</literal> for IPv6. If an empty string is
663 assigned, then the all previous assignments are cleared. This setting is read by
664 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
668 <term><varname>Domains=
</varname></term>
670 <para>A whitespace-separated list of domains which should be resolved using the DNS servers on
671 this link. Each item in the list should be a domain name, optionally prefixed with a tilde
672 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
673 domains without the prefix are called
"search domains" and are first used as search suffixes for
674 extending single-label hostnames (hostnames containing no dots) to become fully qualified
675 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
676 specified search domains are appended to it in turn, converting it into a fully qualified domain
677 name, until one of them may be successfully resolved.
</para>
679 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for hostnames
680 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
681 the DNS servers configured for this interface. The domain routing logic is particularly useful on
682 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
684 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
685 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
686 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
687 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
688 if a link on which they are connected is available.
</para>
690 <para>This setting is read by
691 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
692 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
693 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
694 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
695 name servers limited to a specific link.
</para>
699 <term><varname>DNSDefaultRoute=
</varname></term>
701 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
702 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
703 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
704 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
705 queries not matching any link's configured domains will be routed to this link if it has no routing-only
706 domains configured.
</para>
710 <term><varname>NTP=
</varname></term>
712 <para>An NTP server address (either an IP address, or a hostname). This option may be specified more than once. This setting is read by
713 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
717 <term><varname>IPForward=
</varname></term>
718 <listitem><para>Configures IP packet forwarding for the
719 system. If enabled, incoming packets on any network
720 interface will be forwarded to any other interfaces
721 according to the routing table. Takes a boolean,
722 or the values
<literal>ipv4
</literal> or
723 <literal>ipv6
</literal>, which only enable IP packet
724 forwarding for the specified address family. This controls
725 the
<filename>net.ipv4.ip_forward
</filename> and
726 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
727 options of the network interface (see
<ulink
728 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
729 for details about sysctl options). Defaults to
730 <literal>no
</literal>.
</para>
732 <para>Note: this setting controls a global kernel option,
733 and does so one way only: if a network that has this setting
734 enabled is set up the global setting is turned on. However,
735 it is never turned off again, even after all networks with
736 this setting enabled are shut down again.
</para>
738 <para>To allow IP packet forwarding only between specific
739 network interfaces use a firewall.
</para>
743 <term><varname>IPMasquerade=
</varname></term>
744 <listitem><para>Configures IP masquerading for the network
745 interface. If enabled, packets forwarded from the network
746 interface will be appear as coming from the local host.
747 Takes a boolean argument. Implies
748 <varname>IPForward=ipv4
</varname>. Defaults to
749 <literal>no
</literal>.
</para></listitem>
752 <term><varname>IPv6PrivacyExtensions=
</varname></term>
753 <listitem><para>Configures use of stateless temporary
754 addresses that change over time (see
<ulink
755 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
756 Privacy Extensions for Stateless Address Autoconfiguration
757 in IPv6). Takes a boolean or the special values
758 <literal>prefer-public
</literal> and
759 <literal>kernel
</literal>. When true, enables the privacy
760 extensions and prefers temporary addresses over public
761 addresses. When
<literal>prefer-public
</literal>, enables the
762 privacy extensions, but prefers public addresses over
763 temporary addresses. When false, the privacy extensions
764 remain disabled. When
<literal>kernel
</literal>, the kernel's
765 default setting will be left in place. Defaults to
766 <literal>no
</literal>.
</para></listitem>
769 <term><varname>IPv6AcceptRA=
</varname></term>
770 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
771 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they may
772 trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or if no
773 routers are found on the link. The default is to disable RA reception for bridge devices or when IP
774 forwarding is enabled, and to enable it otherwise. Cannot be enabled on bond devices and when link
775 local addressing is disabled.
</para>
777 <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA] section, see
780 <para>Also see
<ulink
781 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink> in the kernel
782 documentation regarding
<literal>accept_ra
</literal>, but note that systemd's setting of
783 <constant>1</constant> (i.e. true) corresponds to kernel's setting of
<constant>2</constant>.
</para>
785 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
786 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
787 RA protocol is used, and the kernel's own implementation remains disabled, since
788 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
789 and these are not available from the kernel if the kernel's own implementation is used.
</para>
793 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
794 <listitem><para>Configures the amount of IPv6 Duplicate
795 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
799 <term><varname>IPv6HopLimit=
</varname></term>
800 <listitem><para>Configures IPv6 Hop Limit. For each router that
801 forwards the packet, the hop limit is decremented by
1. When the
802 hop limit field reaches zero, the packet is discarded.
803 When unset, the kernel's default will be used.
807 <term><varname>IPv4AcceptLocal=
</varname></term>
808 <listitem><para>Takes a boolean. Accept packets with local source addresses. In combination
809 with suitable routing, this can be used to direct packets between two local interfaces over
810 the wire and have them accepted properly. When unset, the kernel's default will be used.
814 <term><varname>IPv4ProxyARP=
</varname></term>
815 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
816 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
817 the router accepts responsibility for routing packets to the
"real" destination. See
<ulink
818 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
819 When unset, the kernel's default will be used.
823 <term><varname>IPv6ProxyNDP=
</varname></term>
824 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
825 Protocol) is a technique for IPv6 to allow routing of addresses to a different
826 destination when peers expect them to be present on a certain physical link.
827 In this case a router answers Neighbour Advertisement messages intended for
828 another machine by offering its own MAC address as destination.
829 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
830 Advertisement messages for addresses in the IPv6 neighbor proxy table,
831 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
832 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
833 interface depending on this option.
834 When unset, the kernel's default will be used.
838 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
839 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
840 proxied. This option may be specified more than once. systemd-networkd will add the
841 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
842 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
843 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
847 <term><varname>IPv6SendRA=
</varname></term>
848 <listitem><para>Whether to enable or disable Router Advertisement sending on a link. Takes a
849 boolean value. When enabled, prefixes configured in [IPv6Prefix] sections and routes
850 configured in [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA]
851 section. If
<varname>DHCPv6PrefixDelegation=
</varname> is enabled, then the delegated
852 prefixes are also distributed. See
<varname>DHCPv6PrefixDelegation=
</varname> setting and the
853 [IPv6SendRA], [IPv6Prefix], [IPv6RoutePrefix], and [DHCPv6PrefixDelegation] sections for more
854 configuration options.
</para></listitem>
857 <term><varname>DHCPv6PrefixDelegation=
</varname></term>
858 <listitem><para>Takes a boolean value. When enabled, requests prefixes using a DHCPv6 client
859 configured on another link. By default, an address within each delegated prefix will be
860 assigned, and the prefixes will be announced through IPv6 Router Advertisement when
861 <varname>IPv6SendRA=
</varname> is enabled. Such default settings can be configured in
862 [DHCPv6PrefixDelegation] section. Defaults to disabled.
</para></listitem>
865 <term><varname>IPv6MTUBytes=
</varname></term>
866 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
867 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
871 <term><varname>Bridge=
</varname></term>
873 <para>The name of the bridge to add the link to. See
874 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
879 <term><varname>Bond=
</varname></term>
881 <para>The name of the bond to add the link to. See
882 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
887 <term><varname>VRF=
</varname></term>
889 <para>The name of the VRF to add the link to. See
890 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
895 <term><varname>VLAN=
</varname></term>
897 <para>The name of a VLAN to create on the link. See
898 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
899 This option may be specified more than once.
</para>
903 <term><varname>IPVLAN=
</varname></term>
905 <para>The name of a IPVLAN to create on the link. See
906 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
907 This option may be specified more than once.
</para>
911 <term><varname>MACVLAN=
</varname></term>
913 <para>The name of a MACVLAN to create on the link. See
914 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
915 This option may be specified more than once.
</para>
919 <term><varname>VXLAN=
</varname></term>
921 <para>The name of a VXLAN to create on the link. See
922 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
923 This option may be specified more than once.
</para>
927 <term><varname>Tunnel=
</varname></term>
929 <para>The name of a Tunnel to create on the link. See
930 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
931 This option may be specified more than once.
</para>
935 <term><varname>MACsec=
</varname></term>
937 <para>The name of a MACsec device to create on the link. See
938 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
939 This option may be specified more than once.
</para>
943 <term><varname>ActiveSlave=
</varname></term>
945 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
946 option is only valid for following modes:
947 <literal>active-backup
</literal>,
948 <literal>balance-alb
</literal> and
949 <literal>balance-tlb
</literal>. Defaults to false.
954 <term><varname>PrimarySlave=
</varname></term>
956 <para>Takes a boolean. Specifies which slave is the primary device. The specified
957 device will always be the active slave while it is available. Only when the
958 primary is off-line will alternate devices be used. This is useful when
959 one slave is preferred over another, e.g. when one slave has higher throughput
960 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
962 <literal>active-backup
</literal>,
963 <literal>balance-alb
</literal> and
964 <literal>balance-tlb
</literal>. Defaults to false.
969 <term><varname>ConfigureWithoutCarrier=
</varname></term>
971 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
972 Defaults to false. If
<option>IgnoreCarrierLoss=
</option> is not explicitly set, it will
973 default to this value.
978 <term><varname>IgnoreCarrierLoss=
</varname></term>
980 <para>Takes a boolean. Allows networkd to retain both the static and dynamic configuration
981 of the interface even if its carrier is lost. When unset, the value specified with
982 <option>ConfigureWithoutCarrier=
</option> is used.
985 <para>When
<varname>ActivationPolicy=
</varname> is set to
<literal>always-up
</literal>, this
986 is forced to
<literal>true
</literal>.
991 <term><varname>Xfrm=
</varname></term>
993 <para>The name of the xfrm to create on the link. See
994 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
995 This option may be specified more than once.
</para>
999 <term><varname>KeepConfiguration=
</varname></term>
1001 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
1002 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
1003 will not drop static addresses and routes on starting up process. When set to
1004 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
1005 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
1006 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
1007 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
1008 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
1009 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
1010 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
<literal>no
</literal>.
1020 <title>[Address] Section Options
</title>
1022 <para>An [Address] section accepts the following keys. Specify several [Address]
1023 sections to configure several addresses.
</para>
1025 <variablelist class='network-directives'
>
1027 <term><varname>Address=
</varname></term>
1029 <para>As in the [Network] section. This key is mandatory. Each [Address] section can contain one
1030 <varname>Address=
</varname> setting.
</para>
1034 <term><varname>Peer=
</varname></term>
1036 <para>The peer address in a point-to-point connection.
1037 Accepts the same format as the
<varname>Address=
</varname>
1042 <term><varname>Broadcast=
</varname></term>
1044 <para>The broadcast address, which must be in the format
1046 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1047 This key only applies to IPv4 addresses. If it is not
1048 given, it is derived from the
<varname>Address=
</varname>
1053 <term><varname>Label=
</varname></term>
1055 <para>An address label.
</para>
1059 <term><varname>PreferredLifetime=
</varname></term>
1061 <para>Allows the default
"preferred lifetime" of the address to be overridden. Only three
1062 settings are accepted:
<literal>forever
</literal>,
<literal>infinity
</literal>, which is the
1063 default and means that the address never expires, and
<literal>0</literal>, which means that the
1064 address is considered immediately
"expired" and will not be used, unless explicitly requested. A
1065 setting of
<option>PreferredLifetime=
0</option> is useful for addresses which are added to be
1066 used only by a specific application, which is then configured to use them explicitly.
</para>
1070 <term><varname>Scope=
</varname></term>
1072 <para>The scope of the address, which can be
1073 <literal>global
</literal> (valid everywhere on the network, even through a gateway),
1074 <literal>link
</literal> (only valid on this device, will not traverse a gateway) or
1075 <literal>host
</literal> (only valid within the device itself, e.g.
127.0.0.1)
1076 or an unsigned integer in the range
0…
255.
1077 Defaults to
<literal>global
</literal>.
</para>
1081 <term><varname>HomeAddress=
</varname></term>
1083 <para>Takes a boolean. Designates this address the
"home address" as defined in
1084 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
1085 Supported only on IPv6. Defaults to false.
</para>
1089 <term><varname>DuplicateAddressDetection=
</varname></term>
1091 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
1092 <literal>both
</literal>,
<literal>none
</literal>. When
<literal>ipv4
</literal>,
1093 performs IPv4 Duplicate Address Detection. See
1094 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
1095 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
1096 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>.
1097 Defaults to
<literal>ipv6
</literal>.
</para>
1101 <term><varname>ManageTemporaryAddress=
</varname></term>
1103 <para>Takes a boolean. If true the kernel manage temporary addresses created
1104 from this one as template on behalf of Privacy Extensions
1105 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
1106 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
1107 The given address needs to have a prefix length of
64. This flag allows using privacy
1108 extensions in a manually configured network, just like if stateless auto-configuration
1109 was active. Defaults to false.
</para>
1113 <term><varname>AddPrefixRoute=
</varname></term>
1115 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
1116 Defaults to true.
</para>
1120 <term><varname>AutoJoin=
</varname></term>
1122 <para>Takes a boolean. Joining multicast group on ethernet level via
1123 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
1124 IGMP snooping since the switch would not replicate multicast packets on ports that did not
1125 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
1126 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
1127 that enables then to do the required join. By extending ip address command with option
1128 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
1129 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
1130 Defaults to
<literal>no
</literal>.
</para>
1137 <title>[Neighbor] Section Options
</title>
1138 <para>A [Neighbor] section accepts the following keys. The neighbor section adds a permanent, static
1139 entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the links
1140 matched for the network. Specify several [Neighbor] sections to configure several static neighbors.
1143 <variablelist class='network-directives'
>
1145 <term><varname>Address=
</varname></term>
1147 <para>The IP address of the neighbor.
</para>
1151 <term><varname>LinkLayerAddress=
</varname></term>
1153 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
1160 <title>[IPv6AddressLabel] Section Options
</title>
1162 <para>An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel]
1163 sections to configure several address labels. IPv6 address labels are used for address selection. See
1164 <ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>. Precedence is managed by userspace,
1165 and only the label itself is stored in the kernel.
</para>
1167 <variablelist class='network-directives'
>
1169 <term><varname>Label=
</varname></term>
1171 <para>The label for the prefix, an unsigned integer in the range
0–
4294967294.
1172 0xffffffff is reserved. This setting is mandatory.
</para>
1176 <term><varname>Prefix=
</varname></term>
1178 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
1179 This key is mandatory.
</para>
1186 <title>[RoutingPolicyRule] Section Options
</title>
1188 <para>An [RoutingPolicyRule] section accepts the following keys. Specify several [RoutingPolicyRule]
1189 sections to configure several rules.
</para>
1191 <variablelist class='network-directives'
>
1193 <term><varname>TypeOfService=
</varname></term>
1195 <para>Takes a number between
0 and
255 that specifies the type of service to match.
</para>
1199 <term><varname>From=
</varname></term>
1201 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1205 <term><varname>To=
</varname></term>
1207 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1211 <term><varname>FirewallMark=
</varname></term>
1213 <para>Specifies the iptables firewall mark value to match (a number between
1 and
1214 4294967295). Optionally, the firewall mask (also a number between
1 and
4294967295) can be
1215 suffixed with a slash (
<literal>/
</literal>), e.g.,
<literal>7/
255</literal>.
</para>
1219 <term><varname>Table=
</varname></term>
1221 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes one of predefined names
1222 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names defined in
<varname>RouteTable=
</varname>
1223 in
<citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1224 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1228 <term><varname>Priority=
</varname></term>
1230 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1231 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1235 <term><varname>IncomingInterface=
</varname></term>
1237 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1241 <term><varname>OutgoingInterface=
</varname></term>
1243 <para>Specifies the outgoing device to match. The outgoing interface is only available for packets originating from local sockets that are bound to a device.
</para>
1247 <term><varname>SourcePort=
</varname></term>
1249 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1250 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1254 <term><varname>DestinationPort=
</varname></term>
1256 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1257 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1261 <term><varname>IPProtocol=
</varname></term>
1263 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1264 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1265 <literal>17</literal> for
<literal>udp
</literal>.
1266 Defaults to unset.
</para>
1270 <term><varname>InvertRule=
</varname></term>
1272 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1276 <term><varname>Family=
</varname></term>
1278 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1279 <literal>both
</literal>. By default, the address family is determined by the address
1280 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1281 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1282 <literal>ipv4
</literal>.
</para>
1286 <term><varname>User=
</varname></term>
1288 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1293 <term><varname>SuppressPrefixLength=
</varname></term>
1295 <para>Takes a number
<replaceable>N
</replaceable> in the range
0…
128 and rejects routing
1296 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1301 <term><varname>Type=
</varname></term>
1303 <para>Specifies Routing Policy Database (RPDB) rule type. Takes one of
<literal>blackhole
</literal>,
1304 <literal>unreachable
</literal> or
<literal>prohibit
</literal>.
1312 <title>[NextHop] Section Options
</title>
1313 <para>The [NextHop] section is used to manipulate entries in the kernel's
"nexthop" tables. The
1314 [NextHop] section accepts the following keys. Specify several [NextHop] sections to configure several
1317 <variablelist class='network-directives'
>
1319 <term><varname>Gateway=
</varname></term>
1321 <para>As in the [Network] section. This is mandatory.
</para>
1325 <term><varname>Id=
</varname></term>
1327 <para>The id of the nexthop (an unsigned integer). If unspecified or '
0' then automatically chosen by kernel.
</para>
1334 <title>[Route] Section Options
</title>
1335 <para>The [Route] section accepts the following keys. Specify several [Route] sections to configure
1336 several routes.
</para>
1338 <variablelist class='network-directives'
>
1340 <term><varname>Gateway=
</varname></term>
1342 <para>Takes the gateway address or the special values
<literal>_dhcp4
</literal> and
1343 <literal>_ipv6ra
</literal>. If
<literal>_dhcp4
</literal> or
<literal>_ipv6ra
</literal> is
1344 set, then the gateway address provided by DHCPv4 or IPv6 RA is used.
</para>
1348 <term><varname>GatewayOnLink=
</varname></term>
1350 <para>Takes a boolean. If set to true, the kernel does not have
1351 to check if the gateway is reachable directly by the current machine (i.e., the kernel does
1352 not need to check if the gateway is attached to the local network), so that we can insert the
1353 route in the kernel table without it being complained about. Defaults to
<literal>no
</literal>.
1358 <term><varname>Destination=
</varname></term>
1360 <para>The destination prefix of the route. Possibly
1361 followed by a slash and the prefix length. If omitted, a
1362 full-length host route is assumed.
</para>
1366 <term><varname>Source=
</varname></term>
1368 <para>The source prefix of the route. Possibly followed by
1369 a slash and the prefix length. If omitted, a full-length
1370 host route is assumed.
</para>
1374 <term><varname>Metric=
</varname></term>
1376 <para>The metric of the route (an unsigned integer).
</para>
1380 <term><varname>IPv6Preference=
</varname></term>
1382 <para>Specifies the route preference as defined in
<ulink
1383 url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink> for Router Discovery messages. Which
1384 can be one of
<literal>low
</literal> the route has a lowest priority,
<literal>medium
</literal>
1385 the route has a default priority or
<literal>high
</literal> the route has a highest priority.
1390 <term><varname>Scope=
</varname></term>
1392 <para>The scope of the IPv4 route, which can be
<literal>global
</literal>,
<literal>site
</literal>,
1393 <literal>link
</literal>,
<literal>host
</literal>, or
1394 <literal>nowhere
</literal>:
</para>
1396 <listitem><para><literal>global
</literal> means the route can reach
1397 hosts more than one hop away.
</para></listitem>
1399 <listitem><para><literal>site
</literal> means an interior route in
1400 the local autonomous system.
</para></listitem>
1402 <listitem><para><literal>link
</literal> means the route can only
1403 reach hosts on the local network (one hop away).
</para></listitem>
1405 <listitem><para><literal>host
</literal> means the route will not
1406 leave the local machine (used for internal addresses like
1407 127.0.0.1).
</para></listitem>
1409 <listitem><para><literal>nowhere
</literal> means the destination
1410 doesn't exist.
</para></listitem>
1412 <para>For IPv4 route, defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
1413 <literal>local
</literal> or
<literal>nat
</literal>,
1414 and
<literal>link
</literal> if
<varname>Type=
</varname> is
1415 <literal>broadcast
</literal>,
<literal>multicast
</literal>, or
<literal>anycast
</literal>.
1416 In other cases, defaults to
<literal>global
</literal>. The value is
1417 not used for IPv6.
</para>
1421 <term><varname>PreferredSource=
</varname></term>
1423 <para>The preferred source address of the route. The address
1424 must be in the format described in
1425 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1429 <term><varname>Table=
</varname></term>
1431 <para>The table identifier for the route. Takes one of predefined names
<literal>default
</literal>,
<literal>main
</literal>,
1432 and
<literal>local
</literal>, and names defined in
<varname>RouteTable=
</varname> in
<citerefentry><refentrytitle>networkd.conf
</refentrytitle>
1433 <manvolnum>5</manvolnum></citerefentry>, or a number between
1 and
4294967295. The table can be retrieved using
1434 <command>ip route show table
<replaceable>num
</replaceable></command>. If unset and
<varname>Type=
</varname> is
<literal>local
</literal>,
1435 <literal>broadcast
</literal>,
<literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1436 In other cases, defaults to
<literal>main
</literal>.
1441 <term><varname>Protocol=
</varname></term>
1443 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1444 <literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1445 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1450 <term><varname>Type=
</varname></term>
1452 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1453 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1454 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1455 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1456 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1457 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1458 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1459 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1460 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1461 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1462 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1467 <term><varname>InitialCongestionWindow=
</varname></term>
1469 <para>The TCP initial congestion window is used during the start of a TCP connection.
1470 During the start of a TCP session, when a client requests a resource, the server's initial
1471 congestion window determines how many packets will be sent during the initial burst of data
1472 without waiting for acknowledgement. Takes a number between
1 and
1023. Note that
100 is
1473 considered an extremely large value for this option. When unset, the kernel's default
1474 (typically
10) will be used.
</para>
1478 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1480 <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
1481 that can initially be buffered at one time on a connection. The sending host can send only
1482 that amount of data before waiting for an acknowledgment and window update from the
1483 receiving host. Takes a number between
1 and
1023. Note that
100 is considered an extremely
1484 large value for this option. When unset, the kernel's default will be used.
</para>
1488 <term><varname>QuickAck=
</varname></term>
1490 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1495 <term><varname>FastOpenNoCookie=
</varname></term>
1497 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1498 When unset, the kernel's default will be used.
1503 <term><varname>TTLPropagate=
</varname></term>
1505 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1506 When unset, the kernel's default will be used.
1511 <term><varname>MTUBytes=
</varname></term>
1513 <para>The maximum transmission unit in bytes to set for the
1514 route. The usual suffixes K, M, G, are supported and are
1515 understood to the base of
1024.
</para>
1516 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1517 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1521 <term><varname>IPServiceType=
</varname></term>
1523 <para>Takes string;
<literal>CS6
</literal> or
<literal>CS4
</literal>. Used to set IP
1524 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.
</para>
1528 <term><varname>TCPAdvertisedMaximumSegmentSize=
</varname></term>
1530 <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G, are
1531 supported and are understood to the base of
1024. An unsigned integer in the range
1–
4294967294.
1532 When unset, the kernel's default will be used.
</para>
1536 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1538 <para>Configures multipath route. Multipath routing is the technique of using multiple
1539 alternative paths through a network. Takes gateway address. Optionally, takes a network
1540 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for
1541 this multipath route separated with whitespace. This setting can be specified multiple
1542 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
1549 <title>[DHCPv4] Section Options
</title>
1550 <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
1551 <varname>DHCP=
</varname> setting described above:
</para>
1553 <variablelist class='network-directives'
>
1555 <term><varname>UseDNS=
</varname></term>
1557 <para>When true (the default), the DNS servers received
1558 from the DHCP server will be used and take precedence over
1559 any statically configured ones.
</para>
1561 <para>This corresponds to the
<option>nameserver
</option>
1562 option in
<citerefentry
1563 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1567 <term><varname>RoutesToDNS=
</varname></term>
1569 <para>When true, the routes to the DNS servers received from the DHCP server will be
1570 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored.
1571 Defaults to false.
</para>
1575 <term><varname>UseNTP=
</varname></term>
1577 <para>When true (the default), the NTP servers received from the DHCP server will be used by
1578 <filename>systemd-timesyncd.service
</filename> and take precedence over any statically configured
1583 <term><varname>UseSIP=
</varname></term>
1585 <para>When true (the default), the SIP servers received from the DHCP server will be collected
1586 and made available to client programs.
</para>
1591 <term><varname>UseMTU=
</varname></term>
1593 <para>When true, the interface maximum transmission unit
1594 from the DHCP server will be used on the current link.
1595 If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
1596 Defaults to false.
</para>
1600 <term><varname>Anonymize=
</varname></term>
1602 <para>Takes a boolean. When true, the options sent to the DHCP server will
1603 follow the
<ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink>
1604 (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying information.
1605 Defaults to false.
</para>
1607 <para>This option should only be set to true when
1608 <varname>MACAddressPolicy=
</varname> is set to
<literal>random
</literal>
1610 project='man-pages'
><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
1612 <para>Note that this configuration will overwrite others.
1613 In concrete, the following variables will be ignored:
1614 <varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1615 <varname>UseRoutes=
</varname>,
<varname>UseMTU=
</varname>,
1616 <varname>VendorClassIdentifier=
</varname>,
<varname>UseTimezone=
</varname>.
</para>
1618 <para>With this option enabled DHCP requests will mimic those generated by Microsoft Windows, in
1619 order to reduce the ability to fingerprint and recognize installations. This means DHCP request
1620 sizes will grow and lease data will be more comprehensive than normally, though most of the
1621 requested data is not actually used.
</para>
1625 <term><varname>SendHostname=
</varname></term>
1627 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1628 Note that the machine's hostname must consist only of
7-bit ASCII lower-case characters and
1629 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1630 sent even if this is set to true.
</para>
1635 <term><varname>MUDURL=
</varname></term>
1637 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent to the
1638 DHCPv4 server. Takes a URL of length up to
255 characters. A superficial verification that the
1639 string is a valid URL will be performed. DHCPv4 clients are intended to have at most one MUD URL
1640 associated with them. See
<ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
1643 <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers to
1644 advertise device specifications, including the intended communication patterns for their device
1645 when it connects to the network. The network can then use this to author a context-specific
1646 access policy, so the device functions only within those parameters.
</para>
1651 <term><varname>UseHostname=
</varname></term>
1653 <para>When true (the default), the hostname received from
1654 the DHCP server will be set as the transient hostname of the system.
1659 <term><varname>Hostname=
</varname></term>
1661 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1662 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1663 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1667 <term><varname>UseDomains=
</varname></term>
1669 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1670 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1671 the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name received from
1672 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1673 the
<option>Domains=
</option> setting when the argument is prefixed with
<literal>~
</literal>. Defaults to
1676 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1677 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
1678 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1679 single-label names.
</para>
1681 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1682 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1686 <term><varname>UseRoutes=
</varname></term>
1688 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1689 routing table with a metric of
1024, and a scope of
"global",
"link" or
"host", depending on the route's
1690 destination and gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the
1691 link's own address, the scope will be set to
"host". Otherwise if the gateway is null (a direct route), a
1692 "link" scope will be used. For anything else, scope defaults to
"global".
</para>
1696 <term><varname>UseGateway=
</varname></term>
1698 <para>When true, the gateway will be requested from the DHCP server and added to the routing table with a
1699 metric of
1024, and a scope of
"link". When unset, the value specified with
<option>UseRoutes=
</option>
1704 <term><varname>UseTimezone=
</varname></term>
1706 <listitem><para>When true, the timezone received from the
1707 DHCP server will be set as timezone of the local
1708 system. Defaults to
<literal>no
</literal>.
</para></listitem>
1712 <term><varname>ClientIdentifier=
</varname></term>
1714 <para>The DHCPv4 client identifier to use. Takes one of
<literal>mac
</literal>,
<literal>duid
</literal> or
<literal>duid-only
</literal>.
1715 If set to
<literal>mac
</literal>, the MAC address of the link is used.
1716 If set to
<literal>duid
</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1717 If set to
<literal>duid-only
</literal>, only DUID is used, this may not be RFC compliant, but some setups may require to use this.
1718 Defaults to
<literal>duid
</literal>.
</para>
1723 <term><varname>VendorClassIdentifier=
</varname></term>
1725 <para>The vendor class identifier used to identify vendor
1726 type and configuration.
</para>
1731 <term><varname>UserClass=
</varname></term>
1733 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1734 it represents. The information contained in this option is a string that represents the user class of which
1735 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1736 service to classify clients. Takes a whitespace-separated list of strings.
</para>
1741 <term><varname>MaxAttempts=
</varname></term>
1743 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1744 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>. Note that the
1745 time between retries is increased exponentially, up to approximately one per minute, so the
1746 network will not be overloaded even if this number is high. The default is suitable in most
1747 circumstances.
</para>
1752 <term><varname>DUIDType=
</varname></term>
1754 <para>Override the global
<varname>DUIDType
</varname> setting for this network. See
1755 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1756 for a description of possible values.
</para>
1761 <term><varname>DUIDRawData=
</varname></term>
1763 <para>Override the global
<varname>DUIDRawData
</varname> setting for this network. See
1764 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1765 for a description of possible values.
</para>
1770 <term><varname>IAID=
</varname></term>
1772 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned integer.
</para>
1777 <term><varname>RequestBroadcast=
</varname></term>
1779 <para>Request the server to use broadcast messages before
1780 the IP address has been configured. This is necessary for
1781 devices that cannot receive RAW packets, or that cannot
1782 receive packets at all before an IP address has been
1783 configured. On the other hand, this must not be enabled on
1784 networks where broadcasts are filtered out.
</para>
1789 <term><varname>RouteMetric=
</varname></term>
1791 <para>Set the routing metric for routes specified by the DHCP server. Defaults to
1024.
</para>
1796 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1798 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1799 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1801 <para>When used in combination with
<varname>VRF=
</varname>, the
1802 VRF's routing table is used when this parameter is not specified.
1808 <term><varname>RouteMTUBytes=
</varname></term>
1810 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.
</para>
1815 <term><varname>ListenPort=
</varname></term>
1817 <para>Allow setting custom port for the DHCP client to listen on.
</para>
1822 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
1824 <para>Allows to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease lifetime.
1825 Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal> means that the address
1826 never expires. Defaults to unset.
</para>
1831 <term><varname>SendRelease=
</varname></term>
1833 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops.
1834 Defaults to true.
</para>
1839 <term><varname>SendDecline=
</varname></term>
1841 <para>A boolean. When
<literal>true
</literal>, the DHCPv4 client receives the IP address from the
1842 DHCP server. After a new IP is received, the DHCPv4 client performs IPv4 Duplicate Address
1843 Detection. If duplicate use is detected, the DHCPv4 client rejects the IP by sending a
1844 DHCPDECLINE packet and tries to obtain an IP address again. See
<ulink
1845 url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>. Defaults to
1846 <literal>unset
</literal>.
</para>
1851 <term><varname>DenyList=
</varname></term>
1853 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are rejected. Note that
1854 if
<varname>AllowList=
</varname> is configured then
<varname>DenyList=
</varname> is ignored.
</para>
1859 <term><varname>AllowList=
</varname></term>
1861 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are accepted.
</para>
1866 <term><varname>RequestOptions=
</varname></term>
1868 <para>Sets request options to be sent to the server in the DHCPv4 request options list. A
1869 whitespace-separated list of integers in the range
1…
254. Defaults to unset.
</para>
1874 <term><varname>SendOption=
</varname></term>
1876 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data type
1877 and data separated with a colon
1878 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1879 The option number must be an integer in the range
1…
254. The type takes one of
1880 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
1881 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
1882 string may be escaped using
<ulink
1883 url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1884 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1885 then all options specified earlier are cleared. Defaults to unset.
</para>
1890 <term><varname>SendVendorOption=
</varname></term>
1892 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data
1893 type and data separated with a colon
1894 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1895 The option number must be an integer in the range
1…
254. The type takes one of
1896 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
1897 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
1898 string may be escaped using
<ulink
1899 url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1900 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1901 then all options specified earlier are cleared. Defaults to unset.
</para>
1908 <title>[DHCPv6] Section Options
</title>
1909 <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
1910 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
</para>
1912 <variablelist class='network-directives'
>
1914 <term><varname>UseAddress=
</varname></term>
1916 <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
1922 <term><varname>UseDNS=
</varname></term>
1923 <term><varname>UseNTP=
</varname></term>
1925 <para>As in the [DHCPv4] section.
</para>
1930 <term><varname>UseFQDN=
</varname></term>
1932 <para>Equivalent of
<varname>UseHostname=
</varname> in the [DHCPv4] section.
</para>
1937 <term><varname>RouteMetric=
</varname></term>
1939 <para>Set the routing metric for routes specified by the DHCP server. Defaults to
1024.
</para>
1944 <term><varname>RapidCommit=
</varname></term>
1946 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1947 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1948 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1949 four-message exchange (solicit, advertise, request, and reply). The two-message exchange provides
1950 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1951 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
1952 Defaults to true.
</para>
1957 <term><varname>MUDURL=
</varname></term>
1959 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent to
1960 the DHCPv6 server. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
1961 [DHCPv4] section described above.
</para>
1966 <term><varname>RequestOptions=
</varname></term>
1968 <para>When configured, allows to set arbitrary request options in the DHCPv6 request options list
1969 that will be sent to the DHCPv6 server. A whitespace-separated list of integers in the range
1970 1…
254. Defaults to unset.
</para>
1975 <term><varname>SendVendorOption=
</varname></term>
1977 <para>Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier, DHCP
1978 option number, data type, and data separated with a colon (
<literal><replaceable>enterprise
1979 identifier
</replaceable>:
<replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
1980 <replaceable>value
</replaceable></literal>). Enterprise identifier is an unsigned integer in the
1981 range
1–
4294967294. The option number must be an integer in the range
1–
254. Data type takes one
1982 of
<literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
1983 <literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
1984 <literal>string
</literal>. Special characters in the data string may be escaped using
<ulink
1985 url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1986 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1987 then all options specified earlier are cleared. Defaults to unset.
</para>
1992 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
1994 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
1995 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
1996 makes DHCPv6 request network information in a stateless manner using a two-message Information
1997 Request and Information Reply message exchange.
1998 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
1999 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
2000 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
2001 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
2002 By default this option is set to 'false', enable it if no prefixes are delegated when the device
2003 should be acting as a CE router.
</para>
2008 <term><varname>PrefixDelegationHint=
</varname></term>
2010 <para>Takes an IPv6 address with prefix length in the same format as the
2011 <varname>Address=
</varname> in the [Network] section. The DHCPv6 client will include a prefix
2012 hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
2013 1–
128. Defaults to unset.
</para>
2018 <term><varname>WithoutRA=
</varname></term>
2020 <para>Allows DHCPv6 client to start without router advertisements's managed or other address
2021 configuration flag. Takes one of
<literal>solicit
</literal> or
2022 <literal>information-request
</literal>. Defaults to unset.
</para>
2027 <term><varname>SendOption=
</varname></term>
2029 <para>As in the [DHCPv4] section, however because DHCPv6 uses
16-bit fields to store
2030 option numbers, the option number is an integer in the range
1…
65536.
</para>
2035 <term><varname>UserClass=
</varname></term>
2037 <para>A DHCPv6 client can use User Class option to identify the type or category of user or applications
2038 it represents. The information contained in this option is a string that represents the user class of which
2039 the client is a member. Each class sets an identifying string of information to be used by the DHCP
2040 service to classify clients. Special characters in the data string may be escaped using
2041 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2042 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2043 then all options specified earlier are cleared. Takes a whitespace-separated list of strings. Note that
2044 currently
<constant>NUL
</constant> bytes are not allowed.
</para>
2049 <term><varname>VendorClass=
</varname></term>
2051 <para>A DHCPv6 client can use VendorClass option to identify the vendor that
2052 manufactured the hardware on which the client is running. The information
2053 contained in the data area of this option is contained in one or more opaque
2054 fields that identify details of the hardware configuration. Takes a
2055 whitespace-separated list of strings.
</para>
2062 <title>[DHCPv6PrefixDelegation] Section Options
</title>
2063 <para>The [DHCPv6PrefixDelegation] section configures delegated prefixes assigned by DHCPv6 server.
2064 The settings in this section are used only when
<varname>DHCPv6PrefixDelegation=
</varname> setting
2067 <variablelist class='network-directives'
>
2069 <term><varname>SubnetId=
</varname></term>
2071 <para>Configure a specific subnet ID on the interface from a (previously) received prefix
2072 delegation. You can either set
"auto" (the default) or a specific subnet ID (as defined in
2073 <ulink url=
"https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC
4291</ulink>, section
2074 2.5.4), in which case the allowed value is hexadecimal, from
0 to
0x7fffffffffffffff
2080 <term><varname>Announce=
</varname></term>
2082 <para>Takes a boolean. When enabled, and
<varname>IPv6SendRA=
</varname> in [Network] section
2083 is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
2084 Defaults to yes.
</para>
2089 <term><varname>Assign=
</varname></term>
2091 <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
2092 are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
2093 interfce), the EUI-
64 algorithm will be used by default to form an interface identifier from
2094 the delegated prefixes. See also
<varname>Token=
</varname> setting below. Defaults to yes.
2100 <term><varname>Token=
</varname></term>
2102 <para>Specifies an optional address generation mode for assigning an address in each
2103 delegated prefix. Takes an IPv6 address. When set, the lower bits of the supplied address is
2104 combined with the upper bits of each delegatad prefix received from the WAN interface by the
2105 DHCPv6 Prefix Delegation to form a complete address. When
<varname>Assign=
</varname> is
2106 disabled, this setting is ignored. When unset, the EUI-
64 algorithm will be used to form
2107 addresses. Defaults to unset.
</para>
2112 <term><varname>ManageTemporaryAddress=
</varname></term>
2114 <para>As in the [Address] section, but defaults to true.
</para>
2121 <title>[IPv6AcceptRA] Section Options
</title>
2122 <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
2123 with the
<varname>IPv6AcceptRA=
</varname> setting described above:
</para>
2125 <variablelist class='network-directives'
>
2127 <term><varname>UseDNS=
</varname></term>
2129 <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
2130 precedence over any statically configured ones.
</para>
2132 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
2133 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2138 <term><varname>UseDomains=
</varname></term>
2140 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
2141 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
2142 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
2143 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
2144 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
2145 <literal>~
</literal>. Defaults to false.
</para>
2147 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
2148 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
2149 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
2150 single-label names.
</para>
2152 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
2153 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2158 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
2160 <para>The table identifier for the routes received in the Router Advertisement
2161 (a number between
1 and
4294967295, or
0 to unset).
2162 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
2168 <term><varname>UseAutonomousPrefix=
</varname></term>
2170 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
2171 precedence over any statically configured ones.
</para>
2176 <term><varname>UseOnLinkPrefix=
</varname></term>
2178 <para>When true (the default), the onlink prefix received in the Router Advertisement will be
2179 used and takes precedence over any statically configured ones.
</para>
2184 <term><varname>RouterDenyList=
</varname></term>
2186 <para>A whitespace-separated list of IPv6 router addresses. Any information advertised by
2187 the listed router is ignored.
</para>
2192 <term><varname>RouterAllowList=
</varname></term>
2194 <para>A whitespace-separated list of IPv6 router addresses. Only information advertised by
2195 the listed router is accepted. Note that if
<varname>RouterAllowList=
</varname> is
2196 configured then
<varname>RouterDenyList=
</varname> is ignored.
</para>
2201 <term><varname>PrefixDenyList=
</varname></term>
2203 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router
2204 advertisements in the list are ignored.
</para>
2209 <term><varname>PrefixAllowList=
</varname></term>
2211 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router
2212 advertisements in the list are allowed. Note that if
<varname>PrefixAllowList=
</varname> is
2213 configured then
<varname>PrefixDenyList=
</varname> is ignored.
</para>
2218 <term><varname>RouteDenyList=
</varname></term>
2220 <para>A whitespace-separated list of IPv6 route prefixes. IPv6 route prefixes supplied via
2221 router advertisements in the list are ignored.
</para>
2226 <term><varname>RouteAllowList=
</varname></term>
2228 <para>A whitespace-separated list of IPv6 route prefixes. IPv6 route prefixes supplied via
2229 router advertisements in the list are allowed. Note that if
<varname>RouteAllowList=
</varname> is
2230 configured then
<varname>RouteDenyList=
</varname> is ignored.
</para>
2235 <term><varname>DHCPv6Client=
</varname></term>
2237 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true or
2238 <literal>always
</literal>, the DHCPv6 client will be started when the RA has the managed or
2239 other information flag. If set to
<literal>always
</literal>, the DHCPv6 client will also be
2240 started in managed mode when neither managed nor other information flag is set in the RA.
2241 Defaults to true.
</para>
2248 <title>[DHCPServer] Section Options
</title>
2249 <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
2250 <varname>DHCPServer=
</varname> option described above:
</para>
2252 <variablelist class='network-directives'
>
2255 <term><varname>PoolOffset=
</varname></term>
2256 <term><varname>PoolSize=
</varname></term>
2258 <listitem><para>Configures the pool of addresses to hand out. The pool
2259 is a contiguous sequence of IP addresses in the subnet configured for
2260 the server address, which does not include the subnet nor the broadcast
2261 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
2262 from the start of subnet, or zero to use the default value.
2263 <varname>PoolSize=
</varname> takes the number of IP addresses in the
2264 pool or zero to use the default value. By default, the pool starts at
2265 the first address after the subnet address and takes up the rest of
2266 the subnet, excluding the broadcast address. If the pool includes
2267 the server address (the default), this is reserved and not handed
2268 out to clients.
</para></listitem>
2272 <term><varname>DefaultLeaseTimeSec=
</varname></term>
2273 <term><varname>MaxLeaseTimeSec=
</varname></term>
2275 <listitem><para>Control the default and maximum DHCP lease
2276 time to pass to clients. These settings take time values in seconds or
2277 another common time unit, depending on the suffix. The default
2278 lease time is used for clients that did not ask for a specific
2279 lease time. If a client asks for a lease time longer than the
2280 maximum lease time, it is automatically shortened to the
2281 specified time. The default lease time defaults to
1h, the
2282 maximum lease time to
12h. Shorter lease times are beneficial
2283 if the configuration data in DHCP leases changes frequently
2284 and clients shall learn the new settings with shorter
2285 latencies. Longer lease times reduce the generated DHCP
2286 network traffic.
</para></listitem>
2290 <term><varname>EmitDNS=
</varname></term>
2291 <term><varname>DNS=
</varname></term>
2293 <listitem><para><varname>EmitDNS=
</varname> takes a boolean. Configures whether the DHCP leases
2294 handed out to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>. The
2295 DNS servers to pass to clients may be configured with the
<varname>DNS=
</varname> option, which takes
2296 a list of IPv4 addresses. If the
<varname>EmitDNS=
</varname> option is enabled but no servers
2297 configured, the servers are automatically propagated from an
"uplink" interface that has appropriate
2298 servers set. The
"uplink" interface is determined by the default route of the system with the highest
2299 priority. Note that this information is acquired at the time the lease is handed out, and does not
2300 take uplink interfaces into account that acquire DNS server information at a later point. If no
2301 suitable uplink interface is found the DNS server data from
<filename>/etc/resolv.conf
</filename> is
2302 used. Also, note that the leases are not refreshed if the uplink network configuration changes. To
2303 ensure clients regularly acquire the most current uplink DNS server information, it is thus advisable
2304 to shorten the DHCP lease time via
<varname>MaxLeaseTimeSec=
</varname> described
2305 above.
</para></listitem>
2309 <term><varname>EmitNTP=
</varname></term>
2310 <term><varname>NTP=
</varname></term>
2311 <term><varname>EmitSIP=
</varname></term>
2312 <term><varname>SIP=
</varname></term>
2313 <term><varname>EmitPOP3=
</varname></term>
2314 <term><varname>POP3=
</varname></term>
2315 <term><varname>EmitSMTP=
</varname></term>
2316 <term><varname>SMTP=
</varname></term>
2317 <term><varname>EmitLPR=
</varname></term>
2318 <term><varname>LPR=
</varname></term>
2320 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname> settings
2321 described above, these settings configure whether and what server information for the indicate
2322 protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
2323 defaults apply as for
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname>.
</para></listitem>
2327 <term><varname>EmitRouter=
</varname></term>
2329 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
2330 setting described above, this setting configures whether the
2331 DHCP lease should contain the router option. The same syntax,
2332 propagation semantics and defaults apply as for
2333 <varname>EmitDNS=
</varname>.
</para></listitem>
2337 <term><varname>EmitTimezone=
</varname></term>
2338 <term><varname>Timezone=
</varname></term>
2340 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
2341 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
2342 <varname>Timezone=
</varname> setting takes a timezone string
2343 (such as
<literal>Europe/Berlin
</literal> or
2344 <literal>UTC
</literal>) to pass to clients. If no explicit
2345 timezone is set, the system timezone of the local host is
2346 propagated, as determined by the
2347 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
2351 <term><varname>SendOption=
</varname></term>
2353 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
2354 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2355 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
2356 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
2357 <literal>string
</literal>. Special characters in the data string may be escaped using
2358 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2359 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2360 then all options specified earlier are cleared. Defaults to unset.
</para>
2365 <term><varname>SendVendorOption=
</varname></term>
2367 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
2368 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2369 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
2370 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
2371 <literal>string
</literal>. Special characters in the data string may be escaped using
2372 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2373 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2374 then all options specified earlier are cleared. Defaults to unset.
</para>
2382 <title>[IPv6SendRA] Section Options
</title>
2383 <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
2384 to act as a router, if enabled via the
<varname>IPv6SendRA=
</varname> option described above. IPv6
2385 network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
2388 <variablelist class='network-directives'
>
2391 <term><varname>Managed=
</varname></term>
2392 <term><varname>OtherInformation=
</varname></term>
2394 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
2395 addresses on the network link when
<varname>Managed=
</varname>
2396 is set to
<literal>true
</literal> or if only additional network
2397 information can be obtained via DHCPv6 for the network link when
2398 <varname>OtherInformation=
</varname> is set to
2399 <literal>true
</literal>. Both settings default to
2400 <literal>false
</literal>, which means that a DHCPv6 server is not being
2401 used.
</para></listitem>
2405 <term><varname>RouterLifetimeSec=
</varname></term>
2407 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. When set to
2408 0, the host is not acting as a router. Defaults to
30 minutes.
</para>
2413 <term><varname>RouterPreference=
</varname></term>
2415 <listitem><para>Configures IPv6 router preference if
2416 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
2417 <literal>high
</literal>,
<literal>medium
</literal> and
2418 <literal>low
</literal>, with
<literal>normal
</literal> and
2419 <literal>default
</literal> added as synonyms for
2420 <literal>medium
</literal> just to make configuration easier. See
2421 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2422 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
2426 <term><varname>EmitDNS=
</varname></term>
2427 <term><varname>DNS=
</varname></term>
2429 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses that
2430 are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is
2431 true.
<varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that case
2432 the IPv6 link local address is distributed. If
<varname>DNS=
</varname> is empty, DNS servers are read
2433 from the [Network] section. If the [Network] section does not contain any DNS servers either, DNS
2434 servers from the uplink with the highest priority default route are used. When
2435 <varname>EmitDNS=
</varname> is false, no DNS server information is sent in Router Advertisement
2436 messages.
<varname>EmitDNS=
</varname> defaults to true.
</para></listitem>
2440 <term><varname>EmitDomains=
</varname></term>
2441 <term><varname>Domains=
</varname></term>
2443 <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
2444 <varname>EmitDomains=
</varname> is true. If
<varname>Domains=
</varname> is empty, DNS search domains
2445 are read from the [Network] section. If the [Network] section does not contain any DNS search domains
2446 either, DNS search domains from the uplink with the highest priority default route are used. When
2447 <varname>EmitDomains=
</varname> is false, no DNS search domain information is sent in Router
2448 Advertisement messages.
<varname>EmitDomains=
</varname> defaults to true.
</para></listitem>
2452 <term><varname>DNSLifetimeSec=
</varname></term>
2454 <listitem><para>Lifetime in seconds for the DNS server addresses listed
2455 in
<varname>DNS=
</varname> and search domains listed in
2456 <varname>Domains=
</varname>.
</para></listitem>
2463 <title>[IPv6Prefix] Section Options
</title>
2464 <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
2465 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink> for further
2468 <variablelist class='network-directives'
>
2471 <term><varname>AddressAutoconfiguration=
</varname></term>
2472 <term><varname>OnLink=
</varname></term>
2474 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
2475 autoconfigured with this prefix and whether the prefix can be used for
2476 onlink determination. Both settings default to
<literal>true
</literal>
2477 in order to ease configuration.
2482 <term><varname>Prefix=
</varname></term>
2484 <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
2485 IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
2486 <literal>/
</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
2487 prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
2488 prefix to another.
</para></listitem>
2492 <term><varname>PreferredLifetimeSec=
</varname></term>
2493 <term><varname>ValidLifetimeSec=
</varname></term>
2495 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2496 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
2497 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
2498 to
2592000 seconds (
30 days).
</para></listitem>
2502 <term><varname>Assign=
</varname></term>
2503 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
2510 <title>[IPv6RoutePrefix] Section Options
</title>
2511 <para>One or more [IPv6RoutePrefix] sections contain the IPv6
2512 prefix routes that are announced via Router Advertisements. See
2513 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2514 for further details.
</para>
2516 <variablelist class='network-directives'
>
2519 <term><varname>Route=
</varname></term>
2521 <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
2522 IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
2523 separated by a
<literal>/
</literal> character. Use multiple [IPv6PrefixRoutes] sections to configure
2524 multiple IPv6 prefix routes.
</para></listitem>
2528 <term><varname>LifetimeSec=
</varname></term>
2530 <listitem><para>Lifetime for the route prefix measured in
2531 seconds.
<varname>LifetimeSec=
</varname> defaults to
604800 seconds (one week).
2539 <title>[Bridge] Section Options
</title>
2540 <para>The [Bridge] section accepts the following keys:
</para>
2541 <variablelist class='network-directives'
>
2543 <term><varname>UnicastFlood=
</varname></term>
2545 <para>Takes a boolean. Controls whether the bridge should flood
2546 traffic for which an FDB entry is missing and the destination
2547 is unknown through this port. When unset, the kernel's default will be used.
2552 <term><varname>MulticastFlood=
</varname></term>
2554 <para>Takes a boolean. Controls whether the bridge should flood
2555 traffic for which an MDB entry is missing and the destination
2556 is unknown through this port. When unset, the kernel's default will be used.
2561 <term><varname>MulticastToUnicast=
</varname></term>
2563 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2564 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2565 When unset, the kernel's default will be used.
2570 <term><varname>NeighborSuppression=
</varname></term>
2572 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2573 this port. When unset, the kernel's default will be used.
2578 <term><varname>Learning=
</varname></term>
2580 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2581 this port. When unset, the kernel's default will be used.
2586 <term><varname>HairPin=
</varname></term>
2588 <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
2589 was received. When this flag is false, then the bridge will not forward traffic back out of the
2590 receiving port. When unset, the kernel's default will be used.
</para>
2594 <term><varname>UseBPDU=
</varname></term>
2596 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2597 processed by the bridge port. When unset, the kernel's default will be used.
</para>
2601 <term><varname>FastLeave=
</varname></term>
2603 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2604 traffic on a port that receives an IGMP Leave message. It is only used with
2605 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
2609 <term><varname>AllowPortToBeRoot=
</varname></term>
2611 <para>Takes a boolean. Configures whether a given port is allowed to
2612 become a root port. Only used when STP is enabled on the bridge.
2613 When unset, the kernel's default will be used.
</para>
2617 <term><varname>ProxyARP=
</varname></term>
2619 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2620 When unset, the kernel's default will be used.
</para>
2624 <term><varname>ProxyARPWiFi=
</varname></term>
2626 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2627 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
2628 When unset, the kernel's default will be used.
</para>
2632 <term><varname>MulticastRouter=
</varname></term>
2634 <para>Configures this port for having multicast routers attached. A port with a multicast
2635 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
2636 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
2637 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
2638 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
2639 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
2643 <term><varname>Cost=
</varname></term>
2645 <para>Sets the
"cost" of sending packets of this interface.
2646 Each port in a bridge may have a different speed and the cost
2647 is used to decide which link to use. Faster interfaces
2648 should have lower costs. It is an integer value between
1 and
2653 <term><varname>Priority=
</varname></term>
2655 <para>Sets the
"priority" of sending packets on this interface.
2656 Each port in a bridge may have a different priority which is used
2657 to decide which link to use. Lower value means higher priority.
2658 It is an integer value between
0 to
63. Networkd does not set any
2659 default, meaning the kernel default value of
32 is used.
</para>
2665 <title>[BridgeFDB] Section Options
</title>
2666 <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
2667 keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.
</para>
2669 <variablelist class='network-directives'
>
2671 <term><varname>MACAddress=
</varname></term>
2673 <para>As in the [Network] section. This key is mandatory.
</para>
2677 <term><varname>Destination=
</varname></term>
2679 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
2683 <term><varname>VLANId=
</varname></term>
2685 <para>The VLAN ID for the new static MAC table entry. If
2686 omitted, no VLAN ID information is appended to the new static MAC
2691 <term><varname>VNI=
</varname></term>
2693 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2694 the remote VXLAN tunnel endpoint. Takes a number in the range
1…
16777215.
2695 Defaults to unset.
</para>
2699 <term><varname>AssociatedWith=
</varname></term>
2701 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
2702 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
2703 <literal>use
</literal> means the address is in use. User space can use this option to
2704 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
2705 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
2706 means the address is associated with master devices fdb.
<literal>router
</literal> means
2707 the destination address is associated with a router. Note that it's valid if the referenced
2708 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
2714 <title>[BridgeMDB] Section Options
</title>
2715 <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
2716 keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.
</para>
2718 <variablelist class='network-directives'
>
2720 <term><varname>MulticastGroupAddress=
</varname></term>
2722 <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.
</para>
2726 <term><varname>VLANId=
</varname></term>
2728 <para>The VLAN ID for the new entry. Valid ranges are
0 (no VLAN) to
4094. Optional, defaults to
0.
</para>
2735 <title>[LLDP] Section Options
</title>
2736 <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
2738 <variablelist class='network-directives'
>
2740 <term><varname>MUDURL=
</varname></term>
2742 <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
2743 LLDP packets. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
2744 [DHCPv4] section described above.
</para>
2746 <para>The MUD URLs received via LLDP packets are saved and can be read using the
2747 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
2754 <title>[CAN] Section Options
</title>
2755 <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
2756 following keys:
</para>
2757 <variablelist class='network-directives'
>
2759 <term><varname>BitRate=
</varname></term>
2761 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
2762 be used here. Takes a number in the range
1…
4294967295.
</para>
2766 <term><varname>SamplePoint=
</varname></term>
2768 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2769 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2773 <term><varname>DataBitRate=
</varname></term>
2774 <term><varname>DataSamplePoint=
</varname></term>
2776 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
2777 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
2781 <term><varname>FDMode=
</varname></term>
2783 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
2784 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
2785 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys.
</para>
2789 <term><varname>FDNonISO=
</varname></term>
2791 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
2792 interface. When unset, the kernel's default will be used.
</para>
2796 <term><varname>RestartSec=
</varname></term>
2798 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2799 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2800 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2801 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2802 automatic restart off. By default automatic restart is disabled.
</para>
2806 <term><varname>Termination=
</varname></term>
2808 <para>Takes a boolean. When
<literal>yes
</literal>, the termination resistor will be selected for
2809 the bias network. When unset, the kernel's default will be used.
</para>
2813 <term><varname>TripleSampling=
</varname></term>
2815 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2816 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
2820 <term><varname>BusErrorReporting=
</varname></term>
2822 <para>Takes a boolean. When
<literal>yes
</literal>, reporting of CAN bus errors is activated
2823 (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
2824 unable to send recessive bit, bus overload, active error announcement, error occurred on
2825 transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
2826 single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.
</para>
2830 <term><varname>ListenOnly=
</varname></term>
2832 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
2833 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
2834 bit. Listen-only mode is important to debug CAN networks without interfering with the
2835 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
2843 <title>[QDisc] Section Options
</title>
2844 <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).
</para>
2846 <variablelist class='network-directives'
>
2848 <term><varname>Parent=
</varname></term>
2850 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
2851 or
<literal>ingress
</literal>. This is mandatory.
</para>
2855 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2860 <title>[NetworkEmulator] Section Options
</title>
2861 <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
2862 can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
2863 applications, or limit the bandwidth usage of a particular service to simulate internet connections.
2866 <variablelist class='network-directives'
>
2867 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2868 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2871 <term><varname>DelaySec=
</varname></term>
2873 <para>Specifies the fixed amount of delay to be added to all packets going out of the
2874 interface. Defaults to unset.
</para>
2879 <term><varname>DelayJitterSec=
</varname></term>
2881 <para>Specifies the chosen delay to be added to the packets outgoing to the network
2882 interface. Defaults to unset.
</para>
2887 <term><varname>PacketLimit=
</varname></term>
2889 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
2890 An unsigned integer in the range
0–
4294967294. Defaults to
1000.
</para>
2895 <term><varname>LossRate=
</varname></term>
2897 <para>Specifies an independent loss probability to be added to the packets outgoing from the
2898 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2903 <term><varname>DuplicateRate=
</varname></term>
2905 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
2906 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2913 <title>[TokenBucketFilter] Section Options
</title>
2914 <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
2917 <variablelist class='network-directives'
>
2918 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2919 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2922 <term><varname>LatencySec=
</varname></term>
2924 <para>Specifies the latency parameter, which specifies the maximum amount of time a
2925 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
2930 <term><varname>LimitBytes=
</varname></term>
2932 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
2933 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
2934 respectively, to the base of
1024. Defaults to unset.
</para>
2939 <term><varname>BurstBytes=
</varname></term>
2941 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
2942 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
2943 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to
2949 <term><varname>Rate=
</varname></term>
2951 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
2952 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
2953 Defaults to unset.
</para>
2958 <term><varname>MPUBytes=
</varname></term>
2960 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
2961 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2962 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to zero.
</para>
2967 <term><varname>PeakRate=
</varname></term>
2969 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
2970 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2971 1000. Defaults to unset.
</para>
2976 <term><varname>MTUBytes=
</varname></term>
2978 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
2979 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
2980 Defaults to unset.
</para>
2987 <title>[PIE] Section Options
</title>
2988 <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
2989 controller-Enhanced (PIE).
</para>
2991 <variablelist class='network-directives'
>
2992 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2993 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2996 <term><varname>PacketLimit=
</varname></term>
2998 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
2999 incoming packets are dropped. An unsigned integer in the range
1…
4294967294. Defaults to unset and
3000 kernel's default is used.
</para>
3007 <title>[FlowQueuePIE] Section Options
</title>
3008 <para>The
<literal>[FlowQueuePIE]
</literal> section manages the queueing discipline
3009 (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).
</para>
3011 <variablelist class='network-directives'
>
3012 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3013 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3016 <term><varname>PacketLimit=
</varname></term>
3018 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3019 incoming packets are dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and
3020 kernel's default is used.
</para>
3027 <title>[StochasticFairBlue] Section Options
</title>
3028 <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
3031 <variablelist class='network-directives'
>
3032 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3033 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3036 <term><varname>PacketLimit=
</varname></term>
3038 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3039 incoming packets are dropped. An unsigned integer in the range
0–
4294967294. Defaults to unset and
3040 kernel's default is used.
</para>
3047 <title>[StochasticFairnessQueueing] Section Options
</title>
3048 <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
3049 fairness queueing (sfq).
</para>
3051 <variablelist class='network-directives'
>
3052 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3053 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3056 <term><varname>PerturbPeriodSec=
</varname></term>
3058 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
3065 <title>[BFIFO] Section Options
</title>
3066 <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
3069 <variablelist class='network-directives'
>
3070 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3071 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3074 <term><varname>LimitBytes=
</varname></term>
3076 <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
3077 in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
3078 reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
3079 as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
3080 kernel default is used.
</para>
3087 <title>[PFIFO] Section Options
</title>
3088 <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
3091 <variablelist class='network-directives'
>
3092 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3093 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3096 <term><varname>PacketLimit=
</varname></term>
3098 <para>Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents
3099 overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this
3100 limit is reached, incoming packets are dropped. An unsigned integer in the range
3101 0–
4294967294. Defaults to unset and kernel's default is used.
</para>
3108 <title>[PFIFOHeadDrop] Section Options
</title>
3109 <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
3110 Head Drop (pfifo_head_drop).
</para>
3112 <variablelist class='network-directives'
>
3113 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3114 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3117 <term><varname>PacketLimit=
</varname></term>
3119 <para>As in [PFIFO] section.
</para></listitem>
3125 <title>[PFIFOFast] Section Options
</title>
3126 <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
3127 (pfifo_fast).
</para>
3129 <variablelist class='network-directives'
>
3130 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3131 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3136 <title>[CAKE] Section Options
</title>
3137 <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
3140 <variablelist class='network-directives'
>
3141 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3142 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3145 <term><varname>OverheadBytes=
</varname></term>
3147 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative. Takes
3148 an integer in the range from -
64 to
256. Defaults to unset and kernel's default is used.
</para>
3153 <term><varname>Bandwidth=
</varname></term>
3155 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
3156 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
3157 unset and kernel's default is used.
</para>
3164 <title>[ControlledDelay] Section Options
</title>
3165 <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
3166 controlled delay (CoDel).
</para>
3168 <variablelist class='network-directives'
>
3169 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3170 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3173 <term><varname>PacketLimit=
</varname></term>
3175 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3176 incoming packets are dropped. An unsigned integer in the range
0–
4294967294. Defaults to unset and
3177 kernel's default is used.
</para>
3182 <term><varname>TargetSec=
</varname></term>
3184 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
3185 Defaults to unset and kernel's default is used.
</para>
3190 <term><varname>IntervalSec=
</varname></term>
3192 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
3193 become too stale. Defaults to unset and kernel's default is used.
</para>
3198 <term><varname>ECN=
</varname></term>
3200 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3201 unset and kernel's default is used.
</para>
3206 <term><varname>CEThresholdSec=
</varname></term>
3208 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3209 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3216 <title>[DeficitRoundRobinScheduler] Section Options
</title>
3217 <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
3218 Robin Scheduler (DRR).
</para>
3220 <variablelist class='network-directives'
>
3221 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3222 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3227 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
3228 <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
3229 Robin Scheduler (DRR).
</para>
3231 <variablelist class='network-directives'
>
3232 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3233 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3236 <term><varname>QuantumBytes=
</varname></term>
3238 <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
3239 to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3240 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to the MTU of the
3249 <title>[EnhancedTransmissionSelection] Section Options
</title>
3250 <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
3251 Transmission Selection (ETS).
</para>
3253 <variablelist class='network-directives'
>
3254 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3255 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3258 <term><varname>Bands=
</varname></term>
3260 <para>Specifies the number of bands. An unsigned integer in the range
1–
16. This value has to be at
3261 least large enough to cover the strict bands specified through the
<varname>StrictBands=
</varname>
3262 and bandwidth-sharing bands specified in
<varname>QuantumBytes=
</varname>.
</para>
3267 <term><varname>StrictBands=
</varname></term>
3269 <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
3270 the range
1–
16.
</para>
3275 <term><varname>QuantumBytes=
</varname></term>
3277 <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
3278 suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3279 respectively, to the base of
1024. This setting can be specified multiple times. If an empty
3280 string is assigned, then the all previous assignments are cleared.
</para>
3285 <term><varname>PriorityMap=
</varname></term>
3287 <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
3288 separated list of numbers. The first number indicates which band the packets with priority
0 should
3289 be put to, the second is for priority
1, and so on. There can be up to
16 numbers in the list. If
3290 there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
3291 the last one. Each band number must be in the range
0…
255. This setting can be specified multiple
3292 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
3299 <title>[GenericRandomEarlyDetection] Section Options
</title>
3300 <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
3301 Early Detection (GRED).
</para>
3303 <variablelist class='network-directives'
>
3304 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3305 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3308 <term><varname>VirtualQueues=
</varname></term>
3310 <para>Specifies the number of virtual queues. Takes a integer in the range
1…
16. Defaults to unset
3311 and kernel's default is used.
</para>
3316 <term><varname>DefaultVirtualQueue=
</varname></term>
3318 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
3319 Defaults to unset and kernel's default is used.
</para>
3324 <term><varname>GenericRIO=
</varname></term>
3326 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
3327 unset and kernel's default is used.
</para>
3334 <title>[FairQueueingControlledDelay] Section Options
</title>
3335 <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
3336 controlled delay (FQ-CoDel).
</para>
3338 <variablelist class='network-directives'
>
3339 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3340 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3343 <term><varname>PacketLimit=
</varname></term>
3345 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3346 dropped. Defaults to unset and kernel's default is used.
</para>
3351 <term><varname>MemoryLimitBytes=
</varname></term>
3353 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
3354 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3355 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
3360 <term><varname>Flows=
</varname></term>
3362 <para>Specifies the number of flows into which the incoming packets are classified.
3363 Defaults to unset and kernel's default is used.
</para>
3368 <term><varname>TargetSec=
</varname></term>
3370 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
3371 Defaults to unset and kernel's default is used.
</para>
3376 <term><varname>IntervalSec=
</varname></term>
3378 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
3379 become too stale. Defaults to unset and kernel's default is used.
</para>
3384 <term><varname>QuantumBytes=
</varname></term>
3386 <para>Specifies the number of bytes used as the
"deficit" in the fair queuing algorithm timespan.
3387 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3388 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
3393 <term><varname>ECN=
</varname></term>
3395 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3396 unset and kernel's default is used.
</para>
3401 <term><varname>CEThresholdSec=
</varname></term>
3403 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3404 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3411 <title>[FairQueueing] Section Options
</title>
3412 <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
3415 <variablelist class='network-directives'
>
3416 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3417 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3420 <term><varname>PacketLimit=
</varname></term>
3422 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3423 dropped. Defaults to unset and kernel's default is used.
</para>
3428 <term><varname>FlowLimit=
</varname></term>
3430 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
3431 unset and kernel's default is used.
</para>
3436 <term><varname>QuantumBytes=
</varname></term>
3438 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
3439 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3440 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
3441 default is used.
</para>
3446 <term><varname>InitialQuantumBytes=
</varname></term>
3448 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
3449 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
3450 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
3451 kernel's default is used.
</para>
3456 <term><varname>MaximumRate=
</varname></term>
3458 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
3459 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
3460 1000. Defaults to unset and kernel's default is used.
</para>
3465 <term><varname>Buckets=
</varname></term>
3467 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
3468 kernel's default is used.
</para>
3473 <term><varname>OrphanMask=
</varname></term>
3475 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
3476 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
3477 kernel's default is used.
</para>
3482 <term><varname>Pacing=
</varname></term>
3484 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
3485 default is used.
</para>
3490 <term><varname>CEThresholdSec=
</varname></term>
3492 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3493 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3500 <title>[TrivialLinkEqualizer] Section Options
</title>
3501 <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
3502 equalizer (teql).
</para>
3504 <variablelist class='network-directives'
>
3505 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3506 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3509 <term><varname>Id=
</varname></term>
3511 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
3512 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
3513 <constant>max_equalizers=N+
1</constant> option must be loaded before
3514 <command>systemd-networkd
</command> is started.
</para>
3521 <title>[HierarchyTokenBucket] Section Options
</title>
3522 <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
3523 bucket (htb).
</para>
3525 <variablelist class='network-directives'
>
3526 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3527 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3530 <term><varname>DefaultClass=
</varname></term>
3532 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
3533 to the class. Defaults to unset.
</para>
3538 <term><varname>RateToQuantum=
</varname></term>
3540 <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
3541 configured in
<varname>Rate=
</varname> by
<varname>RateToQuantum=
</varname>.
</para>
3548 <title>[HierarchyTokenBucketClass] Section Options
</title>
3549 <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
3552 <variablelist class='network-directives'
>
3553 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3554 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3557 <term><varname>Priority=
</varname></term>
3559 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
3560 priority field are tried for packets first.
</para>
3565 <term><varname>QuantumBytes=
</varname></term>
3567 <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
3568 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
3574 <term><varname>MTUBytes=
</varname></term>
3576 <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
3577 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
3582 <term><varname>OverheadBytes=
</varname></term>
3584 <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
3585 computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3586 Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
3591 <term><varname>Rate=
</varname></term>
3593 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
3594 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
3595 to the base of
1000. This setting is mandatory.
</para>
3600 <term><varname>CeilRate=
</varname></term>
3602 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
3603 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
3604 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
3610 <term><varname>BufferBytes=
</varname></term>
3612 <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
3613 with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
3614 to the base of
1024.
</para>
3619 <term><varname>CeilBufferBytes=
</varname></term>
3621 <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
3622 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3623 respectively, to the base of
1024.
</para>
3630 <title>[HeavyHitterFilter] Section Options
</title>
3631 <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
3634 <variablelist class='network-directives'
>
3635 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3636 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3639 <term><varname>PacketLimit=
</varname></term>
3641 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3642 incoming packets are dropped. An unsigned integer in the range
0–
4294967294. Defaults to unset and
3643 kernel's default is used.
</para>
3650 <title>[QuickFairQueueing] Section Options
</title>
3651 <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
3654 <variablelist class='network-directives'
>
3655 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3656 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3661 <title>[QuickFairQueueingClass] Section Options
</title>
3662 <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
3665 <variablelist class='network-directives'
>
3666 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3667 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3670 <term><varname>Weight=
</varname></term>
3672 <para>Specifies the weight of the class. Takes an integer in the range
1…
1023. Defaults to
3673 unset in which case the kernel default is used.
</para>
3678 <term><varname>MaxPacketBytes=
</varname></term>
3680 <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the
3681 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
3682 1024. When unset, the kernel default is used.
</para>
3689 <title>[BridgeVLAN] Section Options
</title>
3690 <para>The [BridgeVLAN] section manages the VLAN ID configuration of a bridge port and accepts the
3691 following keys. Specify several [BridgeVLAN] sections to configure several VLAN entries. The
3692 <varname>VLANFiltering=
</varname> option has to be enabled, see the [Bridge] section in
3693 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3695 <variablelist class='network-directives'
>
3697 <term><varname>VLAN=
</varname></term>
3699 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
3700 from
1 to
4094.
</para>
3704 <term><varname>EgressUntagged=
</varname></term>
3706 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
3707 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
3708 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
3712 <term><varname>PVID=
</varname></term>
3714 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
3715 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
3716 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
3723 <title>Examples
</title>
3725 <title>Static network configuration
</title>
3727 <programlisting># /etc/systemd/network/
50-static.network
3732 Address=
192.168.0.15/
24
3733 Gateway=
192.168.0.1</programlisting>
3735 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
3736 specified gateway will be used for a default route.
</para>
3740 <title>DHCP on ethernet links
</title>
3742 <programlisting># /etc/systemd/network/
80-dhcp.network
3747 DHCP=yes
</programlisting>
3749 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
3750 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
3754 <title>IPv6 Prefix Delegation
</title>
3756 <programlisting># /etc/systemd/network/
55-ipv6-pd-upstream.network
3761 DHCP=ipv6
</programlisting>
3763 <programlisting># /etc/systemd/network/
56-ipv6-pd-downstream.network
3769 DHCPv6PrefixDelegation=yes
</programlisting>
3771 <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
3772 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
3773 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
3778 <title>A bridge with two enslaved links
</title>
3780 <programlisting># /etc/systemd/network/
25-bridge-static.network
3785 Address=
192.168.0.15/
24
3787 DNS=
192.168.0.1</programlisting>
3789 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
3794 Bridge=bridge0
</programlisting>
3796 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
3801 Bridge=bridge0
</programlisting>
3803 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
3804 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
3805 and network assigned, and a default route via the specified gateway will be
3806 added. The specified DNS server will be added to the global list of DNS resolvers.
3814 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
3830 EgressUntagged=
300-
400</programlisting>
3832 <para>This overrides the configuration specified in the previous example for the
3833 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
3834 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
3835 untagged when they leave on this interface. Untagged packets which arrive on this
3836 interface will be assigned VLAN ID
42.
</para>
3840 <title>Various tunnels
</title>
3842 <programlisting>/etc/systemd/network/
25-tunnels.network
3853 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
3859 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
3865 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
3871 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
3877 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
3878 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
3882 <title>A bond device
</title>
3884 <programlisting># /etc/systemd/network/
30-bond1.network
3892 <programlisting># /etc/systemd/network/
30-bond1.netdev
3898 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
3900 MACAddress=
52:
54:
00:e9:
64:
41
3906 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
3908 MACAddress=
52:
54:
00:e9:
64:
42
3914 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
3915 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
3916 will be used to acquire an address.
</para>
3920 <title>Virtual Routing and Forwarding (VRF)
</title>
3921 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
3922 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
3923 within the routing table defined during VRF creation. For kernels before
4.8 traffic
3924 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
3926 <programlisting># /etc/systemd/network/
25-vrf.network
3936 <title>MacVTap
</title>
3937 <para>This brings up a network interface
<literal>macvtap-test
</literal>
3938 and attaches it to
<literal>enp0s25
</literal>.
</para>
3939 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
3944 MACVTAP=macvtap-test
3949 <title>A Xfrm interface with physical underlying device.
</title>
3951 <programlisting># /etc/systemd/network/
27-xfrm.netdev
3956 InterfaceId=
7</programlisting>
3958 <programlisting># /etc/systemd/network/
27-eth0.network
3963 Xfrm=xfrm0
</programlisting>
3965 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
3966 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
3967 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
3973 <title>See Also
</title>
3975 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
3976 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
3977 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3978 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3979 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>