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
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
45 processed in alphanumeric order, regardless of the directories in which they live. However, files
46 with identical filenames replace each other. It is recommended that each filename is prefixed with
47 a number (e.g.
<filename>10-eth0.network
</filename>). Otherwise, the default
48 <filename>.network
</filename> files or those generated by
49 <citerefentry><refentrytitle>systemd-network-generator.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
50 may take precedence over user configured files. Files in
<filename>/etc/
</filename> have the highest
51 priority, files in
<filename>/run/
</filename> take precedence over files with the same name under
52 <filename>/usr/
</filename>. This can be used to override a system-supplied configuration file with
53 a local file if needed. As a special case, an empty file (file size
0) or symlink with the same
54 name pointing to
<filename>/dev/null
</filename> disables the configuration file entirely (it is
57 <para>Along with the network file
<filename>foo.network
</filename>, a
"drop-in" directory
58 <filename>foo.network.d/
</filename> may exist. All files with the suffix
59 <literal>.conf
</literal> from this directory will be merged in the alphanumeric order and parsed
60 after the main file itself has been parsed. This is useful to alter or add configuration settings,
61 without having to modify the main configuration file. Each drop-in file must have appropriate
62 section headers.
</para>
64 <para>In addition to
<filename>/etc/systemd/network
</filename>, drop-in
<literal>.d
</literal>
65 directories can be placed in
<filename>/usr/lib/systemd/network
</filename> or
66 <filename>/run/systemd/network
</filename> directories. Drop-in files in
67 <filename>/etc/
</filename> take precedence over those in
<filename>/run/
</filename> which in turn
68 take precedence over those in
<filename>/usr/lib/
</filename>. Drop-in files under any of these
69 directories take precedence over the main network file wherever located.
</para>
73 <title>[Match] Section Options
</title>
75 <para>The network file contains a [Match] section, which determines if a given network file may
76 be applied to a given interface; and a [Network] section specifying how the interface should be
77 configured. The first (in alphanumeric order) of the network files that matches a given interface
78 is applied, all later files 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
82 the file will match all interfaces and
<command>systemd-networkd
</command> warns about that. Hint:
83 to avoid 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=
"kind" />
93 <xi:include href=
"systemd.link.xml" xpointer=
"property" />
96 <term><varname>Name=
</varname></term>
98 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
99 by the udev property
<literal>INTERFACE
</literal>, or device's alternative names. If the
100 list is prefixed with a
"!", the test is inverted.
</para>
102 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
107 <term><varname>WLANInterfaceType=
</varname></term>
109 <para>A whitespace-separated list of wireless network type. Supported values are
110 <literal>ad-hoc
</literal>,
<literal>station
</literal>,
<literal>ap
</literal>,
111 <literal>ap-vlan
</literal>,
<literal>wds
</literal>,
<literal>monitor
</literal>,
112 <literal>mesh-point
</literal>,
<literal>p2p-client
</literal>,
<literal>p2p-go
</literal>,
113 <literal>p2p-device
</literal>,
<literal>ocb
</literal>, and
<literal>nan
</literal>. If the
114 list is prefixed with a
"!", the test is inverted.
</para>
116 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
121 <term><varname>SSID=
</varname></term>
123 <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
124 connected wireless LAN. If the list is prefixed with a
"!", the test is inverted.
</para>
126 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
131 <term><varname>BSSID=
</varname></term>
133 <para>A whitespace-separated list of hardware address of the currently connected wireless
134 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
135 <varname>MACAddress=
</varname>. This option may appear more than once, in which case the
136 lists are merged. If the empty string is assigned to this option, the list is reset.
</para>
138 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
142 <xi:include href=
"systemd.link.xml" xpointer=
"host" />
143 <xi:include href=
"systemd.link.xml" xpointer=
"virtualization" />
144 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-command-line" />
145 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-version" />
146 <xi:include href=
"systemd.link.xml" xpointer=
"credential" />
147 <xi:include href=
"systemd.link.xml" xpointer=
"architecture" />
148 <xi:include href=
"systemd.link.xml" xpointer=
"firmware" />
153 <title>[Link] Section Options
</title>
155 <para>The [Link] section accepts the following keys:
</para>
157 <variablelist class='network-directives'
>
159 <term><varname>MACAddress=
</varname></term>
161 <para>The hardware address to set for the device.
</para>
163 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
168 <term><varname>MTUBytes=
</varname></term>
170 <para>The maximum transmission unit in bytes to set for the device. The usual suffixes K, M,
171 G, are supported and are understood to the base of
1024.
</para>
172 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen below
1280 (the
173 minimum MTU for IPv6) it will automatically be increased to this value.
</para>
175 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
180 <term><varname>ARP=
</varname></term>
182 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
183 for this interface is enabled. When unset, the kernel's default will be used.
</para>
184 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
185 interfaces atop a single lower-level physical interface, which will then only serve as a
186 link/
"bridge" device aggregating traffic to the same physical link and not participate in
187 the network otherwise. Defaults to unset.
</para>
189 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
194 <term><varname>Multicast=
</varname></term>
196 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults
199 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
204 <term><varname>AllMulticast=
</varname></term>
206 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the
207 network. This happens when multicast routing is enabled. Defaults to unset.
</para>
209 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
214 <term><varname>Promiscuous=
</varname></term>
216 <para>Takes a boolean. If set to true, promiscuous mode of the interface is enabled. Defaults
218 <para>If this is set to false for the underlying link of a
<literal>passthru
</literal> mode
219 MACVLAN/MACVTAP, the virtual interface will be created with the
<literal>nopromisc
</literal>
222 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
227 <term><varname>Unmanaged=
</varname></term>
229 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are made to bring up or
230 configure matching links, equivalent to when there are no matching network files. Defaults to
231 <literal>no
</literal>.
</para>
232 <para>This is useful for preventing later matching network files from interfering with
233 certain interfaces that are fully controlled by other applications.
</para>
235 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
240 <term><varname>Group=
</varname></term>
242 <para>Link groups are similar to port ranges found in managed switches. When network
243 interfaces are added to a numbered group, operations on all the interfaces from that group
244 can be performed at once. Takes an unsigned integer in the range
0…
2147483647. Defaults to
247 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
252 <term><varname>RequiredForOnline=
</varname></term>
254 <para>Takes a boolean or a minimum operational state and an optional maximum operational
256 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
257 for possible operational states. When
<literal>yes
</literal>, the network is deemed required
258 when determining whether the system is online (including when running
259 <command>systemd-networkd-wait-online
</command>). When
<literal>no
</literal>, the network is
260 ignored when determining the online state. When a minimum operational state and an optional
261 maximum operational state are set,
<literal>yes
</literal> is implied, and this controls the
262 minimum and maximum operational state required for the network interface to be considered
265 <para>Defaults to
<literal>yes
</literal> when
<varname>ActivationPolicy=
</varname> is not
266 set, or set to
<literal>up
</literal>,
<literal>always-up
</literal>, or
267 <literal>bound
</literal>. Defaults to
<literal>no
</literal> when
268 <varname>ActivationPolicy=
</varname> is set to
<literal>manual
</literal> or
269 <literal>down
</literal>. This is forced to
<literal>no
</literal> when
270 <varname>ActivationPolicy=
</varname> is set to
<literal>always-down
</literal>.
</para>
272 <para>The network will be brought up normally (as configured by
273 <varname>ActivationPolicy=
</varname>), but in the event that there is no address being
274 assigned by DHCP or the cable is not plugged in, the link will simply remain offline and be
275 skipped automatically by
<command>systemd-networkd-wait-online
</command> if
276 <literal>RequiredForOnline=no
</literal>.
</para>
278 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
283 <term><varname>RequiredFamilyForOnline=
</varname></term>
285 <para>Takes an address family. When specified, an IP address in the given family is deemed
286 required when determining whether the link is online (including when running
287 <command>systemd-networkd-wait-online
</command>). Takes one of
<literal>ipv4
</literal>,
288 <literal>ipv6
</literal>,
<literal>both
</literal>, or
<literal>any
</literal>. Defaults to
289 <literal>any
</literal>. Note that this option has no effect if
290 <literal>RequiredForOnline=no
</literal>, or if
<literal>RequiredForOnline=
</literal>
291 specifies a minimum operational state below
<literal>degraded
</literal>.
</para>
293 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
298 <term><varname>ActivationPolicy=
</varname></term>
300 <para>Specifies the policy for
<command>systemd-networkd
</command> managing the link
301 administrative state. Specifically, this controls how
<command>systemd-networkd
</command>
302 changes the network device's
<literal>IFF_UP
</literal> flag, which is sometimes
303 controlled by system administrators by running e.g.,
304 <command>ip link set dev eth0 up
</command> or
<command>ip link set dev eth0 down
</command>,
305 and can also be changed with
<command>networkctl up eth0
</command> or
306 <command>networkctl down eth0
</command>.
</para>
308 <para>Takes one of
<literal>up
</literal>,
<literal>always-up
</literal>,
309 <literal>manual
</literal>,
<literal>always-down
</literal>,
<literal>down
</literal>,
310 or
<literal>bound
</literal>. When
<literal>manual
</literal>,
311 <command>systemd-networkd
</command> will not change the link's admin state automatically;
312 the system administrator must bring the interface up or down manually, as desired. When
313 <literal>up
</literal> (the default) or
<literal>always-up
</literal>, or
314 <literal>down
</literal> or
<literal>always-down
</literal>,
315 <command>systemd-networkd
</command> will set the link up or down, respectively, when the
316 interface is (re)configured. When
<literal>always-up
</literal> or
317 <literal>always-down
</literal>,
<command>systemd-networkd
</command> will set the link up or
318 down, respectively, any time
<command>systemd-networkd
</command> detects a change in the
319 administrative state. When
<varname>BindCarrier=
</varname> is also set, this is automatically
320 set to
<literal>bound
</literal> and any other value is ignored.
</para>
322 <para>When the policy is set to
<literal>down
</literal> or
<literal>manual
</literal>, the
323 default value of
<varname>RequiredForOnline=
</varname> is
<literal>no
</literal>. When the
324 policy is set to
<literal>always-down
</literal>, the value of
325 <varname>RequiredForOnline=
</varname> forced to
<literal>no
</literal>.
</para>
327 <para>The administrative state is not the same as the carrier state, so using
328 <literal>always-up
</literal> does not mean the link will never lose carrier. The link carrier
329 depends on both the administrative state as well as the network device's physical connection.
330 However, to avoid reconfiguration failures, when using
<literal>always-up
</literal>,
331 <varname>IgnoreCarrierLoss=
</varname> is forced to true.
</para>
333 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
339 <xi:include href=
"systemd.link.xml" xpointer=
"sr-iov" />
342 <title>[Network] Section Options
</title>
344 <para>The [Network] section accepts the following keys:
</para>
346 <variablelist class='network-directives'
>
348 <term><varname>Description=
</varname></term>
350 <para>A description of the device. This is only used for presentation purposes.
</para>
352 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
357 <term><varname>DHCP=
</varname></term>
359 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
<literal>yes
</literal>,
360 <literal>no
</literal>,
<literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults to
361 <literal>no
</literal>.
</para>
363 <para>Note that DHCPv6 will by default be triggered by Router Advertisements, if reception is
364 enabled, regardless of this parameter. By explicitly enabling DHCPv6 support here, the DHCPv6
365 client will be started in the mode specified by the
<varname>WithoutRA=
</varname> setting in the
366 [DHCPv6] section, regardless of the presence of routers on the link, or what flags the routers
367 pass. See
<varname>IPv6AcceptRA=
</varname>.
</para>
369 <para>Furthermore, note that by default the domain name specified through DHCP is not used
370 for name resolution. See option
<option>UseDomains=
</option> below.
</para>
372 <para>See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the
373 DHCP client support.
</para>
375 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
380 <term><varname>DHCPServer=
</varname></term>
382 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started.
383 Defaults to
<literal>no
</literal>. Further settings for the DHCP server may be set in the
384 [DHCPServer] section described below.
</para>
386 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
391 <term><varname>LinkLocalAddressing=
</varname></term>
393 <para>Enables link-local address autoconfiguration. Accepts
<option>yes
</option>,
394 <option>no
</option>,
<option>ipv4
</option>, and
<option>ipv6
</option>. An IPv6 link-local
395 address is configured when
<option>yes
</option> or
<option>ipv6
</option>. An IPv4 link-local
396 address is configured when
<option>yes
</option> or
<option>ipv4
</option> and when DHCPv4
397 autoconfiguration has been unsuccessful for some time. (IPv4 link-local address
398 autoconfiguration will usually happen in parallel with repeated attempts to acquire a DHCPv4
401 <para>Defaults to
<option>no
</option> when
<varname>KeepMaster=
</varname> or
402 <varname>Bridge=
</varname> is set or when the specified
403 <varname>MACVLAN=
</varname>/
<varname>MACVTAP=
</varname> has
<varname>Mode=passthru
</varname>,
404 or
<option>ipv6
</option> otherwise.
</para>
406 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
411 <term><varname>IPv6LinkLocalAddressGenerationMode=
</varname></term>
413 <para>Specifies how IPv6 link-local address is generated. Takes one of
414 <literal>eui64
</literal>,
<literal>none
</literal>,
<literal>stable-privacy
</literal> and
415 <literal>random
</literal>. When unset,
<literal>stable-privacy
</literal> is used if
416 <varname>IPv6StableSecretAddress=
</varname> is specified, and if not,
417 <literal>eui64
</literal> is used. Note that if
<varname>LinkLocalAddressing=
</varname> is
418 <literal>no
</literal> or
<literal>ipv4
</literal>, then
419 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> will be ignored. Also, even if
420 <varname>LinkLocalAddressing=
</varname> is
<literal>yes
</literal> or
<literal>ipv6
</literal>,
421 setting
<varname>IPv6LinkLocalAddressGenerationMode=none
</varname>
422 disables to configure an IPv6 link-local address.
</para>
424 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
429 <term><varname>IPv6StableSecretAddress=
</varname></term>
431 <para>Takes an IPv6 address. The specified address will be used as a stable secret for
432 generating IPv6 link-local address. If this setting is specified, and
433 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> is unset, then
434 <varname>IPv6LinkLocalAddressGenerationMode=stable-privacy
</varname> is implied.
435 If this setting is not specified, and
<literal>stable-privacy
</literal> is set to
436 <varname>IPv6LinkLocalAddressGenerationMode=
</varname>,
437 then a stable secret address will be generated from the local machine ID and the interface
440 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
445 <term><varname>IPv4LLStartAddress=
</varname></term>
447 <para>Specifies the first IPv4 link-local address to try. Takes an IPv4 address for example
448 169.254.1.2, from the link-local address range:
169.254.0.0/
16 except for
169.254.0.0/
24 and
449 169.254.255.0/
24. This setting may be useful if the device should always have the same address
450 as long as there is no address conflict. When unset, a random address will be automatically
451 selected. Defaults to unset.
</para>
453 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
458 <term><varname>IPv4LLRoute=
</varname></term>
460 <para>Takes a boolean. If set to true, sets up the route needed for non-IPv4LL hosts to
461 communicate with IPv4LL-only hosts. Defaults to false.
</para>
463 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
468 <term><varname>DefaultRouteOnDevice=
</varname></term>
470 <para>Takes a boolean. If set to true, sets up the IPv4 default route bound to the interface.
471 Defaults to false. This is useful when creating routes on point-to-point interfaces. This is
472 equivalent to e.g. the following,
473 <programlisting>ip route add default dev veth99
</programlisting>
475 <programlisting>[Route]
476 Gateway=
0.0.0.0</programlisting></para>
477 <para>Currently, there are no way to specify e.g., the table for the route configured by this
478 setting. To configure the default route with such an additional property, please use the
480 <programlisting>[Route]
482 Table=
1234</programlisting></para>
483 <para>If you'd like to create an IPv6 default route bound to the interface, please use the
485 <programlisting>[Route]
487 Table=
1234</programlisting></para>
489 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
494 <term><varname>LLMNR=
</varname></term>
496 <para>Takes a boolean or
<literal>resolve
</literal>. When true, enables
497 <ulink url=
"https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution
</ulink>
498 on the link. When set to
<literal>resolve
</literal>, only resolution is enabled, but not host
499 registration and announcement. Defaults to true. This setting is read by
500 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
503 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
508 <term><varname>MulticastDNS=
</varname></term>
510 <para>Takes a boolean or
<literal>resolve
</literal>. When true, enables
511 <ulink url=
"https://tools.ietf.org/html/rfc6762">Multicast DNS
</ulink> support on the link.
512 When set to
<literal>resolve
</literal>, only resolution is enabled, but not host or service
513 registration and announcement. Defaults to false. This setting is read by
514 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
517 <xi:include href=
"version-info.xml" xpointer=
"v229"/>
522 <term><varname>DNSOverTLS=
</varname></term>
524 <para>Takes a boolean or
<literal>opportunistic
</literal>. When true, enables
525 <ulink url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink> support on the link.
526 When set to
<literal>opportunistic
</literal>, compatibility with non-DNS-over-TLS servers is
527 increased, by automatically turning off DNS-over-TLS servers in this case. This option
528 defines a per-interface setting for
529 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
530 global
<varname>DNSOverTLS=
</varname> option. Defaults to unset, and the global setting will
531 be used. This setting is read by
532 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
535 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
540 <term><varname>DNSSEC=
</varname></term>
542 <para>Takes a boolean or
<literal>allow-downgrade
</literal>. When true, enables
543 <ulink url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink> DNS validation support on the
544 link. When set to
<literal>allow-downgrade
</literal>, compatibility with non-DNSSEC capable
545 networks is increased, by automatically turning off DNSSEC in this case. This option defines
546 a per-interface setting for
547 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
548 global
<varname>DNSSEC=
</varname> option. Defaults to unset, and the global setting will be
549 used. This setting is read by
550 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
553 <xi:include href=
"version-info.xml" xpointer=
"v229"/>
558 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
560 <para>A space-separated list of DNSSEC negative trust anchor domains. If specified and DNSSEC
561 is enabled, look-ups done via the interface's DNS server will be subject to the list of
562 negative trust anchors, and not require authentication for the specified domains, or anything
563 below it. Use this to disable DNSSEC authentication for specific private domains, that cannot
564 be proven valid using the Internet DNS hierarchy. Defaults to the empty list. This setting is
566 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
569 <xi:include href=
"version-info.xml" xpointer=
"v229"/>
574 <term><varname>LLDP=
</varname></term>
576 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol
577 commonly implemented on professional routers and bridges which announces which physical port
578 a system is connected to, as well as other related data. Accepts a boolean or the special
579 value
<literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a
580 database of all LLDP neighbors maintained. If
<literal>routers-only
</literal> is set only
581 LLDP data of various types of routers is collected and LLDP data about other types of devices
582 ignored (such as stations, telephones and others). If false, LLDP reception is disabled.
583 Defaults to
<literal>routers-only
</literal>. Use
584 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
585 to query the collected neighbor data. LLDP is only available on Ethernet links. See
586 <varname>EmitLLDP=
</varname> below for enabling LLDP packet emission from the local system.
589 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
594 <term><varname>EmitLLDP=
</varname></term>
596 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the
597 special values
<literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
598 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission.
599 If not false, a short LLDP packet with information about the local system is sent out in
600 regular intervals on the link. The LLDP packet will contain information about the local
601 hostname, the local machine ID (as stored in
602 <citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
603 and the local interface name, as well as the pretty hostname of the system (as set in
604 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
605 LLDP emission is only available on Ethernet links. Note that this setting passes data
606 suitable for identification of host to the network and should thus not be enabled on
607 untrusted networks, where such identification data should not be made available. Use this
608 option to permit other systems to identify on which interfaces they are connected to this
609 system. The three special values control propagation of the LLDP packets. The
610 <literal>nearest-bridge
</literal> setting permits propagation only to the nearest connected
611 bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays,
612 but not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until
613 a customer bridge is reached. For details about these concepts, see
614 <ulink url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>.
615 Note that configuring this setting to true is equivalent to
616 <literal>nearest-bridge
</literal>, the recommended and most restricted level of propagation.
617 See
<varname>LLDP=
</varname> above for an option to enable LLDP reception.
</para>
619 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
624 <term><varname>BindCarrier=
</varname></term>
626 <para>A link name or a list of link names. When set, controls the behavior of the current
627 link. When all links in the list are in an operational down state, the current link is
628 brought down. When at least one link has carrier, the current interface is brought up.
</para>
630 <para>This forces
<varname>ActivationPolicy=
</varname> to be set to
<literal>bound
</literal>.
633 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
638 <term><varname>Address=
</varname></term>
640 <para>A static IPv4 or IPv6 address and its prefix length, separated by a
641 <literal>/
</literal> character. Specify this key more than once to configure several
642 addresses. The format of the address must be as described in
643 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
644 This is a short-hand for an [Address] section only containing an Address key (see below).
645 This option may be specified more than once.
</para>
647 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
648 <literal>::
</literal> (for IPv6), a new address range of the requested size is automatically
649 allocated from a system-wide pool of unused ranges. Note that the prefix length must be equal
650 or larger than
8 for IPv4, and
64 for IPv6. The allocated range is checked against all
651 current network interfaces and all known network configuration files to avoid address range
652 conflicts. The default system-wide pool consists of
192.168.0.0/
16,
172.16.0.0/
12 and
653 10.0.0.0/
8 for IPv4, and fd00::/
8 for IPv6. This functionality is useful to manage a large
654 number of dynamically created network interfaces with the same network configuration and
655 automatic address range assignment.
</para>
657 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
662 <term><varname>Gateway=
</varname></term>
664 <para>The gateway address, which must be in the format described in
665 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
666 This is a short-hand for a [Route] section only containing a
<varname>Gateway=
</varname> key.
667 This option may be specified more than once.
</para>
669 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
674 <term><varname>DNS=
</varname></term>
676 <para>A DNS server address, which must be in the format described in
677 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
678 This option may be specified more than once. Each address can optionally take a port number
679 separated with
<literal>:
</literal>, a network interface name or index separated with
680 <literal>%
</literal>, and a Server Name Indication (SNI) separated with
<literal>#
</literal>.
681 When IPv6 address is specified with a port number, then the address must be in the square
682 brackets. That is, the acceptable full formats are
683 <literal>111.222.333.444:
9953%ifname#example.com
</literal> for IPv4 and
684 <literal>[
1111:
2222::
3333]:
9953%ifname#example.com
</literal> for IPv6. If an empty string is
685 assigned, then the all previous assignments are cleared. This setting is read by
686 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
689 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
694 <term><varname>Domains=
</varname></term>
696 <para>A whitespace-separated list of domains which should be resolved using the DNS servers
697 on this link. Each item in the list should be a domain name, optionally prefixed with a tilde
698 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
699 domains without the prefix are called
"search domains" and are first used as search suffixes
700 for extending single-label hostnames (hostnames containing no dots) to become fully qualified
701 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
702 specified search domains are appended to it in turn, converting it into a fully qualified
703 domain name, until one of them may be successfully resolved.
</para>
705 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups
706 for hostnames ending in those domains (hence also single label names, if any
"search domains"
707 are listed), are routed to the DNS servers configured for this interface. The domain routing
708 logic is particularly useful on multi-homed hosts with DNS servers serving particular private
709 DNS zones on each interface.
</para>
711 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a
712 routing domain, the dot referring to the DNS root domain which is the implied suffix of all
713 valid DNS names) has special effect. It causes all DNS traffic which does not match another
714 configured domain routing entry to be routed to DNS servers specified for this interface.
715 This setting is useful to prefer a certain set of DNS servers if a link on which they are
716 connected is available.
</para>
718 <para>This setting is read by
719 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
720 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname>
722 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
723 Domain name routing has no equivalent in the traditional glibc API, which has no concept of
724 domain name servers limited to a specific link.
</para>
726 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
731 <term><varname>DNSDefaultRoute=
</varname></term>
733 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for
734 resolving domain names that do not match any link's configured
<varname>Domains=
</varname>
735 setting. If false, this link's configured DNS servers are never used for such domains, and
736 are exclusively used for resolving names that match at least one of the domains configured on
737 this link. If not specified defaults to an automatic mode: queries not matching any link's
738 configured domains will be routed to this link if it has no routing-only domains configured.
741 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
746 <term><varname>NTP=
</varname></term>
748 <para>An NTP server address (either an IP address, or a hostname). This option may be
749 specified more than once. This setting is read by
750 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
753 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
758 <term><varname>IPForward=
</varname></term>
760 <para>Configures IP packet forwarding for the system. If enabled, incoming packets on any
761 network interface will be forwarded to any other interfaces according to the routing table.
762 Takes a boolean, or the values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>, which only
763 enable IP packet forwarding for the specified address family. This controls the
764 <filename>net.ipv4.ip_forward
</filename> and
<filename>net.ipv6.conf.all.forwarding
</filename>
765 sysctl options of the network interface (see
766 <ulink url=
"https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl
</ulink>
767 for details about sysctl options). Defaults to
<literal>no
</literal>.
</para>
769 <para>Note: this setting controls a global kernel option, and does so one way only: if a
770 network that has this setting enabled is set up the global setting is turned on. However,
771 it is never turned off again, even after all networks with this setting enabled are shut
774 <para>To allow IP packet forwarding only between specific network interfaces use a firewall.
777 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
782 <term><varname>IPMasquerade=
</varname></term>
784 <para>Configures IP masquerading for the network interface. If enabled, packets forwarded
785 from the network interface will be appear as coming from the local host. Takes one of
786 <literal>ipv4
</literal>,
<literal>ipv6
</literal>,
<literal>both
</literal>, or
787 <literal>no
</literal>. Defaults to
<literal>no
</literal>. If enabled, this automatically sets
788 <varname>IPForward=
</varname> to one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal> or
789 <literal>yes
</literal>.
</para>
790 <para>Note. Any positive boolean values such as
<literal>yes
</literal> or
791 <literal>true
</literal> are now deprecated. Please use one of the values in the above.
</para>
793 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
798 <term><varname>IPv6PrivacyExtensions=
</varname></term>
800 <para>Configures use of stateless temporary addresses that change over time (see
801 <ulink url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
802 Privacy Extensions for Stateless Address Autoconfiguration in IPv6). Takes a boolean or the
803 special values
<literal>prefer-public
</literal> and
<literal>kernel
</literal>. When true,
804 enables the privacy extensions and prefers temporary addresses over public addresses. When
805 <literal>prefer-public
</literal>, enables the privacy extensions, but prefers public
806 addresses over temporary addresses. When false, the privacy extensions remain disabled. When
807 <literal>kernel
</literal>, the kernel's default setting will be left in place. When unspecified,
808 the value specified in the same setting in
809 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
810 which defaults to
<literal>no
</literal>, will be used.
</para>
812 <xi:include href=
"version-info.xml" xpointer=
"v222"/>
817 <term><varname>IPv6AcceptRA=
</varname></term>
819 <para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
820 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they
821 may trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or
822 if no routers are found on the link. The default is to disable RA reception for bridge
823 devices or when IP forwarding is enabled, and to enable it otherwise. Cannot be enabled on
824 devices aggregated in a bond device or when link-local addressing is disabled.
</para>
826 <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA]
827 section, see below.
</para>
830 <ulink url=
"https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl
</ulink>
831 in the kernel documentation regarding
<literal>accept_ra
</literal>, but note that systemd's
832 setting of
<constant>1</constant> (i.e. true) corresponds to kernel's setting of
833 <constant>2</constant>.
</para>
835 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
836 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
837 RA protocol is used, and the kernel's own implementation remains disabled, since
838 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
839 and these are not available from the kernel if the kernel's own implementation is used.
842 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
847 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
849 <para>Configures the amount of IPv6 Duplicate Address Detection (DAD) probes to send. When
850 unset, the kernel's default will be used.
</para>
852 <xi:include href=
"version-info.xml" xpointer=
"v228"/>
857 <term><varname>IPv6HopLimit=
</varname></term>
859 <para>Configures IPv6 Hop Limit. For each router that forwards the packet, the hop limit is
860 decremented by
1. When the hop limit field reaches zero, the packet is discarded. When unset,
861 the kernel's default will be used.
</para>
863 <xi:include href=
"version-info.xml" xpointer=
"v228"/>
868 <term><varname>IPv4ReversePathFilter=
</varname></term>
870 <para>Configure IPv4 Reverse Path Filtering. If enabled, when an IPv4 packet is received, the machine will first check
871 whether the
<emphasis>source
</emphasis> of the packet would be routed through the interface it came in. If there is no
872 route to the source on that interface, the machine will drop the packet. Takes one of
873 <literal>no
</literal>,
<literal>strict
</literal>, or
<literal>loose
</literal>. When
<literal>no
</literal>,
874 no source validation will be done. When
<literal>strict
</literal>, mode each incoming packet is tested against the FIB and
875 if the incoming interface is not the best reverse path, the packet check will fail. By default failed packets are discarded.
876 When
<literal>loose
</literal>, mode each incoming packet's source address is tested against the FIB. The packet is dropped
877 only if the source address is not reachable via any interface on that router.
878 See
<ulink url=
"https://tools.ietf.org/html/rfc1027">RFC
3704</ulink>.
879 When unset, the kernel's default will be used.
</para>
881 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
886 <term><varname>IPv4AcceptLocal=
</varname></term>
888 <para>Takes a boolean. Accept packets with local source addresses. In combination with
889 suitable routing, this can be used to direct packets between two local interfaces over the
890 wire and have them accepted properly. When unset, the kernel's default will be used.
</para>
892 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
897 <term><varname>IPv4RouteLocalnet=
</varname></term>
899 <para>Takes a boolean. When true, the kernel does not consider loopback addresses as martian
900 source or destination while routing. This enables the use of
127.0.0.0/
8 for local routing
901 purposes. When unset, the kernel's default will be used.
</para>
903 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
908 <term><varname>IPv4ProxyARP=
</varname></term>
910 <para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one
911 host, usually a router, answers ARP requests intended for another machine. By
"faking" its
912 identity, the router accepts responsibility for routing packets to the
"real" destination.
913 See
<ulink url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>. When unset, the
914 kernel's default will be used.
</para>
916 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
921 <term><varname>IPv6ProxyNDP=
</varname></term>
923 <para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery Protocol)
924 is a technique for IPv6 to allow routing of addresses to a different destination when peers
925 expect them to be present on a certain physical link. In this case a router answers Neighbour
926 Advertisement messages intended for another machine by offering its own MAC address as
927 destination. Unlike proxy ARP for IPv4, it is not enabled globally, but will only send
928 Neighbour Advertisement messages for addresses in the IPv6 neighbor proxy table, which can
929 also be shown by
<command>ip -
6 neighbour show proxy
</command>. systemd-networkd will control
930 the per-interface `proxy_ndp` switch for each configured interface depending on this option.
931 When unset, the kernel's default will be used.
</para>
933 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
938 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
940 <para>An IPv6 address, for which Neighbour Advertisement messages will be proxied. This
941 option may be specified more than once. systemd-networkd will add the
942 <varname>IPv6ProxyNDPAddress=
</varname> entries to the kernel's IPv6 neighbor proxy table.
943 This setting implies
<varname>IPv6ProxyNDP=yes
</varname> but has no effect if
944 <varname>IPv6ProxyNDP=
</varname> has been set to false. When unset, the kernel's default will
947 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
952 <term><varname>IPv6SendRA=
</varname></term>
954 <para>Whether to enable or disable Router Advertisement sending on a link. Takes a boolean
955 value. When enabled, prefixes configured in [IPv6Prefix] sections and routes configured in
956 the [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA] section. If
957 <varname>DHCPPrefixDelegation=
</varname> is enabled, then the delegated prefixes are also
958 distributed. See
<varname>DCHPPrefixDelegation=
</varname> setting and the [IPv6SendRA],
959 [IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation] sections for more configuration
962 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
967 <term><varname>DHCPPrefixDelegation=
</varname></term>
969 <para>Takes a boolean value. When enabled, requests subnet prefixes on another link via the DHCPv6
970 protocol or via the
6RD option in the DHCPv4 protocol. An address within each delegated prefix will
971 be assigned, and the prefixes will be announced through IPv6 Router Advertisement if
972 <varname>IPv6SendRA=
</varname> is enabled. This behaviour can be configured in the
973 [DHCPPrefixDelegation] section. Defaults to disabled.
</para>
975 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
980 <term><varname>IPv6MTUBytes=
</varname></term>
982 <para>Configures IPv6 maximum transmission unit (MTU). An integer greater than or equal to
983 1280 bytes. When unset, the kernel's default will be used.
</para>
985 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
990 <term><varname>KeepMaster=
</varname></term>
992 <para>Takes a boolean value. When enabled, the current master interface index will not be
993 changed, and
<varname>BatmanAdvanced=
</varname>,
<varname>Bond=
</varname>,
994 <varname>Bridge=
</varname>, and
<varname>VRF=
</varname> settings are ignored. This may be
995 useful when a netdev with a master interface is created by another program, e.g.
996 <citerefentry><refentrytitle>systemd-nspawn
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
997 Defaults to false.
</para>
999 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
1004 <term><varname>BatmanAdvanced=
</varname></term>
1005 <term><varname>Bond=
</varname></term>
1006 <term><varname>Bridge=
</varname></term>
1007 <term><varname>VRF=
</varname></term>
1009 <para>The name of the B.A.T.M.A.N. Advanced, bond, bridge, or VRF interface to add the link
1011 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1014 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1019 <term><varname>IPoIB=
</varname></term>
1020 <term><varname>IPVLAN=
</varname></term>
1021 <term><varname>IPVTAP=
</varname></term>
1022 <term><varname>MACsec=
</varname></term>
1023 <term><varname>MACVLAN=
</varname></term>
1024 <term><varname>MACVTAP=
</varname></term>
1025 <term><varname>Tunnel=
</varname></term>
1026 <term><varname>VLAN=
</varname></term>
1027 <term><varname>VXLAN=
</varname></term>
1028 <term><varname>Xfrm=
</varname></term>
1030 <para>The name of an IPoIB, IPVLAN, IPVTAP, MACsec, MACVLAN, MACVTAP, tunnel, VLAN,
1031 VXLAN, or Xfrm to be created on the link. See
1032 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1033 This option may be specified more than once.
</para>
1035 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1040 <term><varname>ActiveSlave=
</varname></term>
1042 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
1043 option is only valid for following modes:
<literal>active-backup
</literal>,
1044 <literal>balance-alb
</literal>, and
<literal>balance-tlb
</literal>. Defaults to false.
</para>
1046 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1051 <term><varname>PrimarySlave=
</varname></term>
1053 <para>Takes a boolean. Specifies which slave is the primary device. The specified device will
1054 always be the active slave while it is available. Only when the primary is off-line will
1055 alternate devices be used. This is useful when one slave is preferred over another, e.g.
1056 when one slave has higher throughput than another. The
<literal>PrimarySlave=
</literal>
1057 option is only valid for following modes:
<literal>active-backup
</literal>,
1058 <literal>balance-alb
</literal>, and
<literal>balance-tlb
</literal>. Defaults to false.
</para>
1060 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1065 <term><varname>ConfigureWithoutCarrier=
</varname></term>
1067 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no
1068 carrier. Defaults to false. If enabled, and the
<varname>IgnoreCarrierLoss=
</varname> setting
1069 is not explicitly set, then it is enabled as well.
</para>
1071 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1076 <term><varname>IgnoreCarrierLoss=
</varname></term>
1078 <para>Takes a boolean or a timespan. When true,
<command>systemd-networkd
</command> retains
1079 both the static and dynamic configuration of the interface even if its carrier is lost. When
1080 false,
<command>systemd-networkd
</command> drops both the static and dynamic configuration of
1081 the interface. When a timespan is specified,
<command>systemd-networkd
</command> waits for
1082 the specified timespan, and ignores the carrier loss if the link regain its carrier within
1083 the timespan. Setting
0 seconds is equivalent to
<literal>no
</literal>, and
1084 <literal>infinite
</literal> is equivalent to
<literal>yes
</literal>.
</para>
1086 <para>Setting a finite timespan may be useful when e.g. in the following cases:
1089 <para>A wireless interface connecting to a network which has multiple access points with
1090 the same SSID.
</para>
1093 <para>Enslaving a wireless interface to a bond interface, which may disconnect from the
1094 connected access point and causes its carrier to be lost.
</para>
1097 <para>The driver of the interface resets when the MTU is changed.
</para>
1102 <para>When
<varname>Bond=
</varname> is specified to a wireless interface, defaults to
3
1103 seconds. When the DHCPv4 client is enabled and
<varname>UseMTU=
</varname> in the [DHCPv4]
1104 section enabled, defaults to
5 seconds. Otherwise, defaults to the value specified with
1105 <varname>ConfigureWithoutCarrier=
</varname>. When
<varname>ActivationPolicy=
</varname> is set
1106 to
<literal>always-up
</literal>, this is forced to
<literal>yes
</literal>, and ignored any
1107 user specified values.
</para>
1109 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
1114 <term><varname>KeepConfiguration=
</varname></term>
1116 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
1117 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
1118 will not drop static addresses and routes on starting up process. When set to
1119 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
1120 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
1121 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
1122 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
1123 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
1124 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
1125 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
1126 <literal>dhcp-on-stop
</literal> when
<command>systemd-networkd
</command> is running in
1127 initrd,
<literal>yes
</literal> when the root filesystem is a network filesystem, and
1128 <literal>no
</literal> otherwise.
</para>
1130 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
1137 <title>[Address] Section Options
</title>
1139 <para>An [Address] section accepts the following keys. Specify several [Address] sections to
1140 configure several addresses.
</para>
1142 <variablelist class='network-directives'
>
1144 <term><varname>Address=
</varname></term>
1146 <para>As in the [Network] section. This setting is mandatory. Each [Address] section can
1147 contain one
<varname>Address=
</varname> setting.
</para>
1149 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1154 <term><varname>Peer=
</varname></term>
1156 <para>The peer address in a point-to-point connection. Accepts the same format as the
1157 <varname>Address=
</varname> setting.
</para>
1159 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
1164 <term><varname>Broadcast=
</varname></term>
1166 <para>Takes an IPv4 address or boolean value. The address must be in the format described in
1167 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1168 If set to true, then the IPv4 broadcast address will be derived from the
1169 <varname>Address=
</varname> setting. If set to false, then the broadcast address will not be
1170 set. Defaults to true, except for wireguard interfaces, where it default to false.
</para>
1172 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1177 <term><varname>Label=
</varname></term>
1179 <para>Specifies the label for the IPv4 address. The label must be a
7-bit ASCII string with
1180 a length of
1…
15 characters. Defaults to unset.
</para>
1182 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1187 <term><varname>PreferredLifetime=
</varname></term>
1189 <para>Allows the default
"preferred lifetime" of the address to be overridden. Only three
1190 settings are accepted:
<literal>forever
</literal>,
<literal>infinity
</literal>, which is the
1191 default and means that the address never expires, and
<literal>0</literal>, which means that
1192 the address is considered immediately
"expired" and will not be used, unless explicitly
1193 requested. A setting of
<option>PreferredLifetime=
0</option> is useful for addresses which
1194 are added to be used only by a specific application, which is then configured to use them
1197 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
1202 <term><varname>Scope=
</varname></term>
1204 <para>The scope of the address, which can be
<literal>global
</literal> (valid everywhere on
1205 the network, even through a gateway),
<literal>link
</literal> (only valid on this device,
1206 will not traverse a gateway) or
<literal>host
</literal> (only valid within the device itself,
1207 e.g.
127.0.0.1) or an integer in the range
0…
255. Defaults to
<literal>global
</literal>.
1208 IPv4 only - IPv6 scope is automatically assigned by the kernel and cannot be set manually.
1211 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1216 <term><varname>RouteMetric=
</varname></term>
1218 <para>The metric of the prefix route, which is pointing to the subnet of the configured IP
1219 address, taking the configured prefix length into account. Takes an unsigned integer in the
1220 range
0…
4294967295. When unset or set to
0, the kernel's default value is used. This
1221 setting will be ignored when
<varname>AddPrefixRoute=
</varname> is false.
</para>
1223 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
1228 <term><varname>HomeAddress=
</varname></term>
1230 <para>Takes a boolean. Designates this address the
"home address" as defined in
1231 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>. Supported only on IPv6.
1232 Defaults to false.
</para>
1234 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1239 <term><varname>DuplicateAddressDetection=
</varname></term>
1241 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
<literal>both
</literal>,
1242 or
<literal>none
</literal>. When
<literal>ipv4
</literal>, performs IPv4 Address Conflict
1243 Detection. See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>.
1244 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
1245 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>. Defaults to
1246 <literal>ipv4
</literal> for IPv4 link-local addresses,
<literal>ipv6
</literal> for IPv6
1247 addresses, and
<literal>none
</literal> otherwise.
</para>
1249 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1254 <term><varname>ManageTemporaryAddress=
</varname></term>
1256 <para>Takes a boolean. If true the kernel manage temporary addresses created from this one as
1257 template on behalf of Privacy Extensions
1258 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become active,
1259 the use_tempaddr sysctl setting has to be set to a value greater than zero. The given address
1260 needs to have a prefix length of
64. This flag allows using privacy extensions in a manually
1261 configured network, just like if stateless auto-configuration was active. Defaults to false.
1264 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1269 <term><varname>AddPrefixRoute=
</varname></term>
1271 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
1272 Defaults to true.
</para>
1274 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
1279 <term><varname>AutoJoin=
</varname></term>
1281 <para>Takes a boolean. Joining multicast group on ethernet level via
1282 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
1283 IGMP snooping since the switch would not replicate multicast packets on ports that did not
1284 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
1285 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
1286 that enables them to do the required join. By extending
<command>ip address
</command> command
1287 with option
<literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS)
1288 vxlan interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
1289 Defaults to
<literal>no
</literal>.
</para>
1291 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1296 <term><varname>NetLabel=
</varname><replaceable>label
</replaceable></term>
1299 <para>This setting provides a method for integrating static and dynamic network configuration into
1300 Linux
<ulink url=
"https://docs.kernel.org/netlabel/index.html">NetLabel
</ulink> subsystem rules,
1301 used by
<ulink url=
"https://en.wikipedia.org/wiki/Linux_Security_Modules">Linux Security Modules
1302 (LSMs)
</ulink> for network access control. The label, with suitable LSM rules, can be used to
1303 control connectivity of (for example) a service with peers in the local network. At least with
1304 SELinux, only the ingress can be controlled but not egress. The benefit of using this setting is
1305 that it may be possible to apply interface independent part of NetLabel configuration at very early
1306 stage of system boot sequence, at the time when the network interfaces are not available yet, with
1308 project='man-pages'
><refentrytitle>netlabelctl
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1309 and the per-interface configuration with
<command>systemd-networkd
</command> once the interfaces
1310 appear later. Currently this feature is only implemented for SELinux.
</para>
1312 <para>The option expects a single NetLabel label. The label must conform to lexical restrictions of
1313 LSM labels. When an interface is configured with IP addresses, the addresses and subnetwork masks
1314 will be appended to the
<ulink
1315 url=
"https://github.com/SELinuxProject/selinux-notebook/blob/main/src/network_support.md">NetLabel
1316 Fallback Peer Labeling
</ulink> rules. They will be removed when the interface is
1317 deconfigured. Failures to manage the labels will be ignored.
</para>
1319 <para>Warning: Once labeling is enabled for network traffic, a lot of LSM access control points in
1320 Linux networking stack go from dormant to active. Care should be taken to avoid getting into a
1321 situation where for example remote connectivity is broken, when the security policy hasn't been
1322 updated to consider LSM per-packet access controls and no rules would allow any network
1323 traffic. Also note that additional configuration with
<citerefentry
1324 project='man-pages'
><refentrytitle>netlabelctl
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1328 <programlisting>[Address]
1329 NetLabel=system_u:object_r:localnet_peer_t:s0
</programlisting>
1331 With the example rules applying for interface
<literal>eth0
</literal>, when the interface is
1332 configured with an IPv4 address of
10.0.0.123/
8,
<command>systemd-networkd
</command> performs the
1333 equivalent of
<command>netlabelctl
</command> operation
1335 <programlisting>netlabelctl unlbl add interface eth0 address:
10.0.0.0/
8 label:system_u:object_r:localnet_peer_t:s0
</programlisting>
1337 and the reverse operation when the IPv4 address is deconfigured. The configuration can be used with
1338 LSM rules; in case of SELinux to allow a SELinux domain to receive data from objects of SELinux
1339 <literal>peer
</literal> class. For example:
1341 <programlisting>type localnet_peer_t;
1342 allow my_server_t localnet_peer_t:peer recv;
</programlisting>
1344 The effect of the above configuration and rules (in absence of other rules as may be the case) is
1345 to only allow
<literal>my_server_t
</literal> (and nothing else) to receive data from local subnet
1346 10.0.0.0/
8 of interface
<literal>eth0
</literal>.
1349 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
1354 <term><varname>NFTSet=
</varname><replaceable>source
</replaceable>:
<replaceable>family
</replaceable>:
<replaceable>table
</replaceable>:
<replaceable>set
</replaceable></term>
1356 <para>This setting provides a method for integrating network configuration into firewall rules with
1357 <ulink url=
"https://netfilter.org/projects/nftables/index.html">NFT
</ulink> sets. The benefit of
1358 using the setting is that static network configuration (or dynamically obtained network addresses,
1359 see similar directives in other sections) can be used in firewall rules with the indirection of NFT
1360 set types. For example, access could be granted for hosts in the local subnetwork only. Firewall
1361 rules using IP address of an interface are also instantly updated when the network configuration
1362 changes, for example via DHCP.
</para>
1364 <para>This option expects a whitespace separated list of NFT set definitions. Each definition
1365 consists of a colon-separated tuple of source type (one of
<literal>address
</literal>,
1366 <literal>prefix
</literal> or
<literal>ifindex
</literal>), NFT address family (one of
1367 <literal>arp
</literal>,
<literal>bridge
</literal>,
<literal>inet
</literal>,
<literal>ip
</literal>,
1368 <literal>ip6
</literal>, or
<literal>netdev
</literal>), table name and set name. The names of tables
1369 and sets must conform to lexical restrictions of NFT table names. The type of the element used in
1370 the NFT filter must match the type implied by the directive (
<literal>address
</literal>,
1371 <literal>prefix
</literal> or
<literal>ifindex
</literal>) and address type (IPv4 or IPv6) as shown
1372 in the table below.
</para>
1375 <title>Defined
<varname>source type
</varname> values
</title>
1377 <colspec colname='source type'
/>
1378 <colspec colname='description'
/>
1379 <colspec colname='NFT type name'
/>
1382 <entry>Source type
</entry>
1383 <entry>Description
</entry>
1384 <entry>Corresponding NFT type name
</entry>
1390 <entry><literal>address
</literal></entry>
1391 <entry>host IP address
</entry>
1392 <entry><literal>ipv4_addr
</literal> or
<literal>ipv6_addr
</literal></entry>
1395 <entry><literal>prefix
</literal></entry>
1396 <entry>network prefix
</entry>
1397 <entry><literal>ipv4_addr
</literal> or
<literal>ipv6_addr
</literal>, with
<literal>flags interval
</literal></entry>
1400 <entry><literal>ifindex
</literal></entry>
1401 <entry>interface index
</entry>
1402 <entry><literal>iface_index
</literal></entry>
1408 <para>When an interface is configured with IP addresses, the addresses, subnetwork masks or
1409 interface index will be appended to the NFT sets. The information will be removed when the
1410 interface is deconfigured.
<command>systemd-networkd
</command> only inserts elements to (or removes
1411 from) the sets, so the related NFT rules, tables and sets must be prepared elsewhere in
1412 advance. Failures to manage the sets will be ignored.
</para>
1415 <programlisting>[Address]
1416 NFTSet=prefix:netdev:filter:eth_ipv4_prefix
</programlisting>
1417 Corresponding NFT rules:
1418 <programlisting>table netdev filter {
1419 set eth_ipv4_prefix {
1424 type filter hook ingress device
"eth0" priority filter; policy drop;
1425 ip daddr != @eth_ipv4_prefix drop
1431 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
1438 <title>[Neighbor] Section Options
</title>
1440 <para>A [Neighbor] section accepts the following keys. The neighbor section adds a permanent,
1441 static entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the
1442 links matched for the network. Specify several [Neighbor] sections to configure several static
1445 <variablelist class='network-directives'
>
1447 <term><varname>Address=
</varname></term>
1449 <para>The IP address of the neighbor.
</para>
1451 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1456 <term><varname>LinkLayerAddress=
</varname></term>
1458 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
1460 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
1467 <title>[IPv6AddressLabel] Section Options
</title>
1469 <para>An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel]
1470 sections to configure several address labels. IPv6 address labels are used for address selection.
1471 See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>. Precedence is managed by
1472 userspace, and only the label itself is stored in the kernel.
</para>
1474 <variablelist class='network-directives'
>
1476 <term><varname>Label=
</varname></term>
1478 <para>The label for the prefix, an unsigned integer in the range
0…
4294967294.
0xffffffff is
1479 reserved. This setting is mandatory.
</para>
1481 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1486 <term><varname>Prefix=
</varname></term>
1488 <para>IPv6 prefix is an address with a prefix length, separated by a slash
1489 <literal>/
</literal> character. This setting is mandatory.
</para>
1491 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1498 <title>[RoutingPolicyRule] Section Options
</title>
1500 <para>An [RoutingPolicyRule] section accepts the following settings. Specify several
1501 [RoutingPolicyRule] sections to configure several rules.
</para>
1503 <variablelist class='network-directives'
>
1505 <term><varname>TypeOfService=
</varname></term>
1508 This specifies the Type of Service (ToS) field of packets to match;
1509 it takes an unsigned integer in the range
0…
255.
1510 The field can be used to specify precedence (the first
3 bits) and ToS (the next
3 bits).
1511 The field can be also used to specify Differentiated Services Code Point (DSCP) (the first
6 bits) and
1512 Explicit Congestion Notification (ECN) (the last
2 bits).
1513 See
<ulink url=
"https://en.wikipedia.org/wiki/Type_of_service">Type of Service
</ulink>
1514 and
<ulink url=
"https://en.wikipedia.org/wiki/Differentiated_services">Differentiated services
</ulink>
1518 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1523 <term><varname>From=
</varname></term>
1525 <para>Specifies the source address prefix to match. Possibly followed by a slash and the
1526 prefix length.
</para>
1528 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1533 <term><varname>To=
</varname></term>
1535 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the
1536 prefix length.
</para>
1538 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1543 <term><varname>FirewallMark=
</varname></term>
1545 <para>Specifies the iptables firewall mark value to match (a number in the range
1546 1…
4294967295). Optionally, the firewall mask (also a number between
1…
4294967295) can be
1547 suffixed with a slash (
<literal>/
</literal>), e.g.,
<literal>7/
255</literal>.
</para>
1549 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1554 <term><varname>Table=
</varname></term>
1556 <para>Specifies the routing table identifier to look up if the rule selector matches. Takes
1557 one of predefined names
<literal>default
</literal>,
<literal>main
</literal>, and
1558 <literal>local
</literal>, and names defined in
<varname>RouteTable=
</varname> in
1559 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1560 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1562 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1567 <term><varname>Priority=
</varname></term>
1569 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an integer in the
1570 range
0…
4294967295. Higher number means lower priority, and rules get processed in order of
1571 increasing number. Defaults to unset, and the kernel will pick a value dynamically.
</para>
1573 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1578 <term><varname>IncomingInterface=
</varname></term>
1580 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches
1581 packets originating from this host.
</para>
1583 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
1588 <term><varname>OutgoingInterface=
</varname></term>
1590 <para>Specifies the outgoing device to match. The outgoing interface is only available for
1591 packets originating from local sockets that are bound to a device.
</para>
1593 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
1598 <term><varname>SourcePort=
</varname></term>
1600 <para>Specifies the source IP port or IP port range match in forwarding information base
1601 (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
1602 Defaults to unset.
</para>
1604 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1609 <term><varname>DestinationPort=
</varname></term>
1611 <para>Specifies the destination IP port or IP port range match in forwarding information base
1612 (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
1613 Defaults to unset.
</para>
1615 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1620 <term><varname>IPProtocol=
</varname></term>
1622 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP
1623 protocol name such as
<literal>tcp
</literal>,
<literal>udp
</literal> or
1624 <literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
1625 <literal>tcp
</literal> or
<literal>17</literal> for
<literal>udp
</literal>. Defaults to unset.
1628 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1633 <term><varname>InvertRule=
</varname></term>
1635 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1637 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1642 <term><varname>Family=
</varname></term>
1644 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1645 <literal>both
</literal>. By default, the address family is determined by the address
1646 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1647 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1648 <literal>ipv4
</literal>.
</para>
1650 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
1655 <term><varname>User=
</varname></term>
1657 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1660 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
1665 <term><varname>SuppressPrefixLength=
</varname></term>
1667 <para>Takes a number
<replaceable>N
</replaceable> in the range
0…
128 and rejects routing
1668 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1671 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
1676 <term><varname>SuppressInterfaceGroup=
</varname></term>
1678 <para>Takes an integer in the range
0…
2147483647 and rejects routing decisions that have
1679 an interface with the same group id. It has the same meaning as
1680 <option>suppress_ifgroup
</option> in
<command>ip rule
</command>. Defaults to unset.
</para>
1682 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
1687 <term><varname>Type=
</varname></term>
1689 <para>Specifies Routing Policy Database (RPDB) rule type. Takes one of
1690 <literal>blackhole
</literal>,
<literal>unreachable
</literal> or
<literal>prohibit
</literal>.
1693 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1700 <title>[NextHop] Section Options
</title>
1702 <para>The [NextHop] section is used to manipulate entries in the kernel's
"nexthop" tables. The
1703 [NextHop] section accepts the following settings. Specify several [NextHop] sections to configure
1704 several hops.
</para>
1706 <variablelist class='network-directives'
>
1708 <term><varname>Id=
</varname></term>
1710 <para>The id of the next hop. Takes an integer in the range
1…
4294967295. If unspecified,
1711 then automatically chosen by kernel.
</para>
1713 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
1718 <term><varname>Gateway=
</varname></term>
1720 <para>As in the [Network] section.
</para>
1722 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
1727 <term><varname>Family=
</varname></term>
1729 <para>Takes one of the special values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>.
1730 By default, the family is determined by the address specified in
1731 <varname>Gateway=
</varname>. If
<varname>Gateway=
</varname> is not specified, then defaults
1732 to
<literal>ipv4
</literal>.
</para>
1734 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1739 <term><varname>OnLink=
</varname></term>
1741 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1742 reachable directly by the current machine (i.e., attached to the local network), so that we
1743 can insert the nexthop in the kernel table without it being complained about. Defaults to
1744 <literal>no
</literal>.
</para>
1746 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1751 <term><varname>Blackhole=
</varname></term>
1753 <para>Takes a boolean. If enabled, packets to the corresponding routes are discarded
1754 silently, and
<varname>Gateway=
</varname> cannot be specified. Defaults to
1755 <literal>no
</literal>.
</para>
1757 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1762 <term><varname>Group=
</varname></term>
1764 <para>Takes a whitespace separated list of nexthop IDs. Each ID must be in the range
1765 1…
4294967295. Optionally, each nexthop ID can take a weight after a colon
1766 (
<literal><replaceable>id
</replaceable><optional>:
<replaceable>weight
</replaceable></optional></literal>).
1767 The weight must be in the range
1…
255. If the weight is not specified, then it is assumed
1768 that the weight is
1. This setting cannot be specified with
<varname>Gateway=
</varname>,
1769 <varname>Family=
</varname>,
<varname>Blackhole=
</varname>. This setting can be specified
1770 multiple times. If an empty string is assigned, then the all previous assignments are
1771 cleared. Defaults to unset.
</para>
1773 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
1780 <title>[Route] Section Options
</title>
1782 <para>The [Route] section accepts the following settings. Specify several [Route] sections to
1783 configure several routes.
</para>
1785 <variablelist class='network-directives'
>
1787 <term><varname>Gateway=
</varname></term>
1789 <para>Takes the gateway address or the special values
<literal>_dhcp4
</literal> and
1790 <literal>_ipv6ra
</literal>. If
<literal>_dhcp4
</literal> or
<literal>_ipv6ra
</literal> is
1791 set, then the gateway address provided by DHCPv4 or IPv6 RA is used.
</para>
1793 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1798 <term><varname>GatewayOnLink=
</varname></term>
1800 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1801 reachable directly by the current machine (i.e., attached to the local network), so that we
1802 can insert the route in the kernel table without it being complained about. Defaults to
1803 <literal>no
</literal>.
</para>
1805 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1810 <term><varname>Destination=
</varname></term>
1812 <para>The destination prefix of the route. Possibly followed by a slash and the prefix
1813 length. If omitted, a full-length host route is assumed.
</para>
1815 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1820 <term><varname>Source=
</varname></term>
1822 <para>The source prefix of the route. Possibly followed by a slash and the prefix length. If
1823 omitted, a full-length host route is assumed.
</para>
1825 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
1830 <term><varname>Metric=
</varname></term>
1832 <para>The metric of the route. Takes an unsigned integer in the range
0…
4294967295. Defaults
1833 to unset, and the kernel's default will be used.
</para>
1835 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
1840 <term><varname>IPv6Preference=
</varname></term>
1842 <para>Specifies the route preference as defined in
1843 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink> for Router Discovery
1844 messages. Which can be one of
<literal>low
</literal> the route has a lowest priority,
1845 <literal>medium
</literal> the route has a default priority or
<literal>high
</literal> the
1846 route has a highest priority.
</para>
1848 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1853 <term><varname>Scope=
</varname></term>
1855 <para>The scope of the IPv4 route, which can be
<literal>global
</literal>,
1856 <literal>site
</literal>,
<literal>link
</literal>,
<literal>host
</literal>, or
1857 <literal>nowhere
</literal>:
</para>
1860 <para><literal>global
</literal> means the route can reach hosts more than one hop away.
1865 <para><literal>site
</literal> means an interior route in the local autonomous system.
1870 <para><literal>link
</literal> means the route can only reach hosts on the local network
1871 (one hop away).
</para>
1875 <para><literal>host
</literal> means the route will not leave the local machine (used for
1876 internal addresses like
127.0.0.1).
</para>
1880 <para><literal>nowhere
</literal> means the destination doesn't exist.
</para>
1884 <para>For IPv4 route, defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
1885 <literal>local
</literal> or
<literal>nat
</literal>, and
<literal>link
</literal> if
1886 <varname>Type=
</varname> is
<literal>broadcast
</literal>,
<literal>multicast
</literal>,
1887 <literal>anycast
</literal>, or
<literal>unicast
</literal>. In other cases,
1888 defaults to
<literal>global
</literal>. The value is not used for IPv6.
</para>
1890 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
1895 <term><varname>PreferredSource=
</varname></term>
1897 <para>The preferred source address of the route. The address must be in the format described
1899 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1902 <xi:include href=
"version-info.xml" xpointer=
"v227"/>
1907 <term><varname>Table=
</varname></term>
1909 <para>The table identifier for the route. Takes one of predefined names
1910 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
1911 defined in
<varname>RouteTable=
</varname> in
1912 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1913 or a number between
1 and
4294967295. The table can be retrieved using
1914 <command>ip route show table
<replaceable>num
</replaceable></command>. If unset and
1915 <varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1916 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1917 In other cases, defaults to
<literal>main
</literal>.
</para>
1919 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
1924 <term><varname>HopLimit=
</varname></term>
1926 <para>Configures per route hop limit. Takes an integer in the range
1…
255. See also
1927 <varname>IPv6HopLimit=
</varname>.
</para>
1929 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
1934 <term><varname>Protocol=
</varname></term>
1936 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special
1937 values
<literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1938 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1941 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1946 <term><varname>Type=
</varname></term>
1948 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1949 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1950 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1951 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1952 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e.
1953 a route indicating the path to take to a destination network address. If
1954 <literal>blackhole
</literal>, packets to the defined route are discarded silently. If
1955 <literal>unreachable
</literal>, packets to the defined route are discarded and the ICMP
1956 message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets to the
1957 defined route are discarded and the ICMP message
"Communication Administratively Prohibited"
1958 is generated. If
<literal>throw
</literal>, route lookup in the current routing table will
1959 fail and the route selection process will return to Routing Policy Database (RPDB). Defaults
1960 to
<literal>unicast
</literal>.
</para>
1962 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1967 <term><varname>InitialCongestionWindow=
</varname></term>
1969 <para>The TCP initial congestion window is used during the start of a TCP connection.
1970 During the start of a TCP session, when a client requests a resource, the server's initial
1971 congestion window determines how many packets will be sent during the initial burst of data
1972 without waiting for acknowledgement. Takes a number between
1 and
1023. Note that
100 is
1973 considered an extremely large value for this option. When unset, the kernel's default
1974 (typically
10) will be used.
</para>
1976 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
1981 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1983 <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
1984 that can initially be buffered at one time on a connection. The sending host can send only
1985 that amount of data before waiting for an acknowledgment and window update from the
1986 receiving host. Takes a number between
1 and
1023. Note that
100 is considered an extremely
1987 large value for this option. When unset, the kernel's default will be used.
</para>
1989 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
1994 <term><varname>QuickAck=
</varname></term>
1996 <para>Takes a boolean. When true, the TCP quick ACK mode for the route is enabled. When unset,
1997 the kernel's default will be used.
</para>
1999 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
2004 <term><varname>FastOpenNoCookie=
</varname></term>
2006 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
2007 When unset, the kernel's default will be used.
</para>
2009 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2014 <term><varname>TTLPropagate=
</varname></term>
2016 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
2017 When unset, the kernel's default will be used.
</para>
2019 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2024 <term><varname>MTUBytes=
</varname></term>
2026 <para>The maximum transmission unit in bytes to set for the route. The usual suffixes K, M,
2027 G, are supported and are understood to the base of
1024.
</para>
2029 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
2034 <term><varname>TCPAdvertisedMaximumSegmentSize=
</varname></term>
2036 <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G,
2037 are supported and are understood to the base of
1024. An unsigned integer in the range
2038 1…
4294967294. When unset, the kernel's default will be used.
</para>
2040 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2045 <term><varname>TCPCongestionControlAlgorithm=
</varname></term>
2047 <para>Specifies the TCP congestion control algorithm for the route. Takes a name of the algorithm,
2048 e.g.
<literal>bbr
</literal>,
<literal>dctcp
</literal>, or
<literal>vegas
</literal>. When unset,
2049 the kernel's default will be used.
</para>
2051 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2056 <term><varname>TCPRetransmissionTimeoutSec=
</varname></term>
2058 <para>Specifies the TCP Retransmission Timeout (RTO) for the route. Takes time values in seconds.
2059 This value specifies the timeout of an alive TCP connection, when retransmissions remain
2060 unacknowledged. When unset, the kernel's default will be used.
</para>
2062 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2067 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
2069 <para>Configures multipath route. Multipath routing is the technique of using multiple
2070 alternative paths through a network. Takes gateway address. Optionally, takes a network
2071 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for this
2072 multipath route separated with whitespace. This setting can be specified multiple times. If
2073 an empty string is assigned, then the all previous assignments are cleared.
</para>
2075 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2080 <term><varname>NextHop=
</varname></term>
2082 <para>Specifies the nexthop id. Takes an unsigned integer in the range
1…
4294967295. If set,
2083 the corresponding [NextHop] section must be configured. Defaults to unset.
</para>
2085 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2092 <title>[DHCPv4] Section Options
</title>
2094 <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
2095 <varname>DHCP=
</varname> setting described above:
</para>
2097 <variablelist class='network-directives'
>
2099 <!-- DHCP packet contents -->
2102 <term><varname>RequestAddress=
</varname></term>
2104 <para>Takes an IPv4 address. When specified, the Requested IP Address option (option code
50) is
2105 added with it to the initial DHCPDISCOVER message sent by the DHCP client. Defaults to unset, and
2106 an already assigned dynamic address to the interface is automatically picked.
</para>
2108 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2113 <term><varname>SendHostname=
</varname></term>
2115 <para>When true (the default), the machine's hostname (or the value specified with
2116 <varname>Hostname=
</varname>, described below) will be sent to the DHCP server. Note that the
2117 hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and be
2118 formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option
2121 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
2126 <term><varname>Hostname=
</varname></term>
2128 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's
2129 hostname. Note that the specified hostname must consist only of
7-bit ASCII lower-case
2130 characters and no spaces or dots, and be formatted as a valid DNS domain name.
</para>
2132 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
2137 <term><varname>MUDURL=
</varname></term>
2139 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent
2140 to the DHCPv4 server. Takes a URL of length up to
255 characters. A superficial verification
2141 that the string is a valid URL will be performed. DHCPv4 clients are intended to have at most
2142 one MUD URL associated with them. See
2143 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
2145 <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers
2146 to advertise device specifications, including the intended communication patterns for their
2147 device when it connects to the network. The network can then use this to author a
2148 context-specific access policy, so the device functions only within those parameters.
</para>
2150 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2155 <term><varname>ClientIdentifier=
</varname></term>
2157 <para>The DHCPv4 client identifier to use. Takes one of
<option>mac
</option> or
2158 <option>duid
</option>. If set to
<option>mac
</option>, the MAC address of the link is used. If set
2159 to
<option>duid
</option>, an RFC4361-compliant Client ID, which is the combination of IAID and
2160 DUID, is used. IAID can be configured by
<varname>IAID=
</varname>. DUID can be configured by
2161 <varname>DUIDType=
</varname> and
<varname>DUIDRawData=
</varname>. Defaults to
2162 <option>duid
</option>.
</para>
2164 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
2169 <term><varname>VendorClassIdentifier=
</varname></term>
2171 <para>The vendor class identifier used to identify vendor type and configuration.
</para>
2173 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2178 <term><varname>UserClass=
</varname></term>
2180 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or
2181 applications it represents. The information contained in this option is a string that
2182 represents the user class of which the client is a member. Each class sets an identifying
2183 string of information to be used by the DHCP service to classify clients. Takes a
2184 whitespace-separated list of strings.
</para>
2186 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
2191 <term><varname>DUIDType=
</varname></term>
2193 <para>Override the global
<varname>DUIDType=
</varname> setting for this network. See
2194 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2195 for a description of possible values.
</para>
2197 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2202 <term><varname>DUIDRawData=
</varname></term>
2204 <para>Override the global
<varname>DUIDRawData=
</varname> setting for this network. See
2205 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2206 for a description of possible values.
</para>
2208 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2213 <term><varname>IAID=
</varname></term>
2215 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned
2218 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2223 <term><varname>Anonymize=
</varname></term>
2225 <para>Takes a boolean. When true, the options sent to the DHCP server will follow the
2226 <ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink> (Anonymity Profiles for
2227 DHCP Clients) to minimize disclosure of identifying information. Defaults to false.
</para>
2229 <para>This option should only be set to true when
<varname>MACAddressPolicy=
</varname> is set
2230 to
<option>random
</option> (see
2231 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
2235 <varname>ClientIdentifier=mac
</varname>,
2236 <varname>SendHostname=no
</varname>,
2237 <varname>Use6RD=no
</varname>,
2238 <varname>UseCaptivePortal=no
</varname>,
2239 <varname>UseMTU=no
</varname>,
2240 <varname>UseNTP=no
</varname>,
2241 <varname>UseSIP=no
</varname>, and
2242 <varname>UseTimezone=no
</varname>
2243 are implied and these settings in the .network file are silently ignored. Also,
2244 <varname>Hostname=
</varname>,
2245 <varname>MUDURL=
</varname>,
2246 <varname>RequestAddress
</varname>,
2247 <varname>RequestOptions=
</varname>,
2248 <varname>SendOption=
</varname>,
2249 <varname>SendVendorOption=
</varname>,
2250 <varname>UserClass=
</varname>, and
2251 <varname>VendorClassIdentifier=
</varname>
2252 are silently ignored.
</para>
2254 <para>With this option enabled DHCP requests will mimic those generated by Microsoft
2255 Windows, in order to reduce the ability to fingerprint and recognize installations. This
2256 means DHCP request sizes will grow and lease data will be more comprehensive than normally,
2257 though most of the requested data is not actually used.
</para>
2259 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
2264 <term><varname>RequestOptions=
</varname></term>
2266 <para>Sets request options to be sent to the server in the DHCPv4 request options list. A
2267 whitespace-separated list of integers in the range
1…
254. Defaults to unset.
</para>
2269 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2274 <term><varname>SendOption=
</varname></term>
2276 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data
2277 type and data separated with a colon
2278 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2279 The option number must be an integer in the range
1…
254. The type takes one of
2280 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
2281 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
2282 string may be escaped using
2283 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2284 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2285 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
2287 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2292 <term><varname>SendVendorOption=
</varname></term>
2294 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data
2295 type and data separated with a colon
2296 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2297 The option number must be an integer in the range
1…
254. The type takes one of
2298 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
2299 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
2300 string may be escaped using
2301 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2302 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2303 then all options specified earlier are cleared. Defaults to unset.
</para>
2305 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2310 <term><varname>IPServiceType=
</varname></term>
2312 <para>Takes one of the special values
<literal>none
</literal>,
<literal>CS6
</literal>, or
2313 <literal>CS4
</literal>. When
<literal>none
</literal> no IP service type is set to the packet
2314 sent from the DHCPv4 client. When
<literal>CS6
</literal> (network control) or
2315 <literal>CS4
</literal> (realtime), the corresponding service type will be set. Defaults to
2316 <literal>CS6
</literal>.
</para>
2318 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2323 <term><varname>SocketPriority=
</varname></term>
2325 <para>The Linux socket option
<constant>SO_PRIORITY
</constant> applied to the raw IP socket used for
2326 initial DHCPv4 messages. Unset by default. Usual values range from
0 to
6.
2327 More details about
<constant>SO_PRIORITY
</constant> socket option in
2328 <citerefentry project='man-pages'
><refentrytitle>socket
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
2329 Can be used in conjunction with [VLAN] section
<varname>EgressQOSMaps=
</varname> setting of .netdev
2330 file to set the
802.1Q VLAN ethernet tagged header priority, see
2331 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2334 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
2338 <!-- How to use the DHCP lease -->
2341 <term><varname>Label=
</varname></term>
2343 <para>Specifies the label for the IPv4 address received from the DHCP server. The label must
2344 be a
7-bit ASCII string with a length of
1…
15 characters. Defaults to unset.
</para>
2346 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2351 <term><varname>UseDNS=
</varname></term>
2353 <para>When true (the default), the DNS servers received from the DHCP server will be used.
2356 <para>This corresponds to the
<option>nameserver
</option> option in
2357 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2360 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2365 <term><varname>RoutesToDNS=
</varname></term>
2367 <para>When true, the routes to the DNS servers received from the DHCP server will be
2368 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored. Defaults to
2371 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2376 <term><varname>UseNTP=
</varname></term>
2378 <para>When true (the default), the NTP servers received from the DHCP server will be used by
2379 <filename>systemd-timesyncd.service
</filename>.
</para>
2381 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
2386 <term><varname>RoutesToNTP=
</varname></term>
2388 <para>When true, the routes to the NTP servers received from the DHCP server will be
2389 configured. When
<varname>UseNTP=
</varname> is disabled, this setting is ignored. Defaults to
2392 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
2397 <term><varname>UseSIP=
</varname></term>
2399 <para>When true (the default), the SIP servers received from the DHCP server will be collected
2400 and made available to client programs.
</para>
2402 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2407 <term><varname>UseCaptivePortal=
</varname></term>
2409 <para>When true (the default), the captive portal advertised by the DHCP server will be recorded
2410 and made available to client programs and displayed in the networkctl status output per-link.
</para>
2412 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
2417 <term><varname>UseMTU=
</varname></term>
2419 <para>When true, the interface maximum transmission unit from the DHCP server will be used on
2420 the current link. If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
2421 Defaults to false.
</para>
2423 <para>Note, some drivers will reset the interfaces if the MTU is changed. For such
2424 interfaces, please try to use
<varname>IgnoreCarrierLoss=
</varname> with a short timespan,
2425 e.g.
<literal>3 seconds
</literal>.
</para>
2427 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2432 <term><varname>UseHostname=
</varname></term>
2434 <para>When true (the default), the hostname received from the DHCP server will be set as the
2435 transient hostname of the system.
</para>
2437 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2442 <term><varname>UseDomains=
</varname></term>
2444 <para>Takes a boolean, or the special value
<option>route
</option>. When true, the domain name
2445 received from the DHCP server will be used as DNS search domain over this link, similarly to the
2446 effect of the
<option>Domains=
</option> setting. If set to
<option>route
</option>, the domain name
2447 received from the DHCP server will be used for routing DNS queries only, but not for searching,
2448 similarly to the effect of the
<option>Domains=
</option> setting when the argument is prefixed with
2449 <literal>~
</literal>. Defaults to false.
</para>
2451 <para>It is recommended to enable this option only on trusted networks, as setting this
2452 affects resolution of all hostnames, in particular of single-label names. It is generally
2453 safer to use the supplied domain only as routing domain, rather than as search domain, in
2454 order to not have it affect local resolution of single-label names.
</para>
2456 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
2457 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2460 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2465 <term><varname>UseRoutes=
</varname></term>
2467 <para>When true (the default), the static routes will be requested from the DHCP server and
2468 added to the routing table with a metric of
1024, and a scope of
<option>global
</option>,
2469 <option>link
</option> or
<option>host
</option>, depending on the route's destination and
2470 gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the link's
2471 own address, the scope will be set to
<option>host
</option>. Otherwise if the gateway is null
2472 (a direct route), a
<option>link
</option> scope will be used. For anything else, scope
2473 defaults to
<option>global
</option>.
</para>
2475 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
2480 <term><varname>RouteMetric=
</varname></term>
2482 <para>Set the routing metric for routes specified by the DHCP server (including the prefix
2483 route added for the specified prefix). Takes an unsigned integer in the range
0…
4294967295.
2484 Defaults to
1024.
</para>
2486 <xi:include href=
"version-info.xml" xpointer=
"v217"/>
2491 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
2493 <para>The table identifier for DHCP routes. Takes one of predefined names
2494 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
2495 defined in
<varname>RouteTable=
</varname> in
2496 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2497 or a number between
1…
4294967295.
</para>
2499 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
2500 used when this parameter is not specified.
</para>
2502 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
2507 <term><varname>RouteMTUBytes=
</varname></term>
2509 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further
2512 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2517 <term><varname>QuickAck=
</varname></term>
2519 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
2520 the acquired DHCPv4 lease. When unset, the kernel's default will be used.
</para>
2522 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
2527 <term><varname>InitialCongestionWindow=
</varname></term>
2529 <para>As in the [Route] section.
</para>
2531 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2536 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
2538 <para>As in the [Route] section.
</para>
2540 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2545 <term><varname>UseGateway=
</varname></term>
2547 <para>When true, the gateway will be requested from the DHCP server and added to the routing
2548 table with a metric of
1024, and a scope of
<option>link
</option>. When unset, the value
2549 specified with
<varname>UseRoutes=
</varname> is used.
</para>
2551 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2556 <term><varname>UseTimezone=
</varname></term>
2557 <listitem><para>When true, the timezone received from the DHCP server will be set as timezone
2558 of the local system. Defaults to false.
</para>
2560 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
2564 <term><varname>Use6RD=
</varname></term>
2566 <para>When true, subnets of the received IPv6 prefix are assigned to downstream interfaces
2567 which enables
<varname>DHCPPrefixDelegation=
</varname>. See also
2568 <varname>DHCPPrefixDelegation=
</varname> in the [Network] section, the [DHCPPrefixDelegation]
2569 section, and
<ulink url=
"https://tools.ietf.org/html/rfc5969">RFC
5969</ulink>. Defaults to
2572 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2577 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
2579 <para>Allows one to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease
2580 lifetime. Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal>. If
2581 specified, the acquired address never expires. Defaults to unset.
</para>
2583 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2587 <!-- How to communicate with the server -->
2590 <term><varname>RequestBroadcast=
</varname></term>
2592 <para>Request the server to use broadcast messages before the IP address has been configured.
2593 This is necessary for devices that cannot receive RAW packets, or that cannot receive packets
2594 at all before an IP address has been configured. On the other hand, this must not be enabled
2595 on networks where broadcasts are filtered out.
</para>
2597 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2602 <term><varname>MaxAttempts=
</varname></term>
2604 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
2605 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>. Note that the
2606 time between retries is increased exponentially, up to approximately one per minute, so the
2607 network will not be overloaded even if this number is high. The default is suitable in most
2608 circumstances.
</para>
2610 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2615 <term><varname>ListenPort=
</varname></term>
2617 <para>Set the port from which the DHCP client packets originate.
</para>
2619 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
2624 <term><varname>DenyList=
</varname></term>
2626 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2627 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are rejected.
2628 Note that if
<varname>AllowList=
</varname> is configured then
<varname>DenyList=
</varname> is
2631 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2636 <term><varname>AllowList=
</varname></term>
2638 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2639 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are accepted.
2642 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2647 <term><varname>SendRelease=
</varname></term>
2649 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops. Defaults to
2652 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2657 <term><varname>SendDecline=
</varname></term>
2659 <para>A boolean. When true,
<command>systemd-networkd
</command> performs IPv4 Duplicate
2660 Address Detection to the acquired address by the DHCPv4 client. If duplicate is detected,
2661 the DHCPv4 client rejects the address by sending a
<constant>DHCPDECLINE
</constant> packet to
2662 the DHCP server, and tries to obtain an IP address again. See
2663 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>. Defaults to false.
</para>
2665 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2670 <term><varname>NetLabel=
</varname></term>
2672 <para>This applies the NetLabel for the addresses received with DHCP, like
2673 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
2674 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
2676 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2681 <term><varname>NFTSet=
</varname></term>
2683 <para>This applies the NFT set for the network configuration received with DHCP, like
2684 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
2685 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
2686 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
2687 <literal>ipv4_addr
</literal>.
</para>
2689 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2696 <title>[DHCPv6] Section Options
</title>
2698 <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
2699 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
2702 <variablelist class='network-directives'
>
2704 <!-- DHCP packet contents -->
2707 <term><varname>MUDURL=
</varname></term>
2708 <term><varname>IAID=
</varname></term>
2709 <term><varname>DUIDType=
</varname></term>
2710 <term><varname>DUIDRawData=
</varname></term>
2711 <term><varname>RequestOptions=
</varname></term>
2713 <para>As in the [DHCPv4] section.
</para>
2715 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2720 <term><varname>SendOption=
</varname></term>
2722 <para>As in the [DHCPv4] section, however because DHCPv6 uses
16-bit fields to store option
2723 numbers, the option number is an integer in the range
1…
65536.
</para>
2725 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2730 <term><varname>SendVendorOption=
</varname></term>
2732 <para>Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier,
2733 DHCP option number, data type, and data separated with a colon
2734 (
<literal><replaceable>enterprise identifier
</replaceable>:
<replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2735 Enterprise identifier is an unsigned integer in the range
1…
4294967294. The option number
2736 must be an integer in the range
1…
254. Data type takes one of
<literal>uint8
</literal>,
2737 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
2738 <literal>ipv6address
</literal>, or
<literal>string
</literal>. Special characters in the data
2739 string may be escaped using
2740 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2741 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2742 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
2744 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2749 <term><varname>UserClass=
</varname></term>
2751 <para>A DHCPv6 client can use User Class option to identify the type or category of user or
2752 applications it represents. The information contained in this option is a string that
2753 represents the user class of which the client is a member. Each class sets an identifying
2754 string of information to be used by the DHCP service to classify clients. Special characters
2755 in the data string may be escaped using
2756 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2757 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2758 specified, then all options specified earlier are cleared. Takes a whitespace-separated list
2759 of strings. Note that currently
<constant>NUL
</constant> bytes are not allowed.
</para>
2761 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2766 <term><varname>VendorClass=
</varname></term>
2768 <para>A DHCPv6 client can use VendorClass option to identify the vendor that manufactured the
2769 hardware on which the client is running. The information contained in the data area of this
2770 option is contained in one or more opaque fields that identify details of the hardware
2771 configuration. Takes a whitespace-separated list of strings.
</para>
2773 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2778 <term><varname>PrefixDelegationHint=
</varname></term>
2780 <para>Takes an IPv6 address with prefix length in the same format as the
2781 <varname>Address=
</varname> in the [Network] section. The DHCPv6 client will include a prefix
2782 hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
2783 1…
128. Defaults to unset.
</para>
2785 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2790 <term><varname>RapidCommit=
</varname></term>
2792 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server
2793 through a rapid two-message exchange (solicit and reply). When the rapid commit option is set by
2794 both the DHCPv6 client and the DHCPv6 server, the two-message exchange is used. Otherwise, the
2795 four-message exchange (solicit, advertise, request, and reply) is used. The two-message exchange
2796 provides faster client configuration. See
2797 <ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
2798 Defaults to true, and the two-message exchange will be used if the server support it.
</para>
2800 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2804 <!-- How to use the DHCP lease -->
2807 <term><varname>UseAddress=
</varname></term>
2809 <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
2812 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2817 <term><varname>UseCaptivePortal=
</varname></term>
2819 <para>When true (the default), the captive portal advertised by the DHCPv6 server will be recorded
2820 and made available to client programs and displayed in the networkctl status output per-link.
</para>
2822 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
2827 <term><varname>UseDelegatedPrefix=
</varname></term>
2829 <para>When true (the default), the client will request the DHCPv6 server to delegate
2830 prefixes. If the server provides prefixes to be delegated, then subnets of the prefixes are
2831 assigned to the interfaces that have
<varname>DHCPPrefixDelegation=yes
</varname>.
2832 See also the
<varname>DHCPPrefixDelegation=
</varname> setting in the [Network] section,
2833 settings in the [DHCPPrefixDelegation] section, and
2834 <ulink url=
"https://www.rfc-editor.org/rfc/rfc8415.html#section-6.3">RFC
8415</ulink>.
2837 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2842 <term><varname>UseDNS=
</varname></term>
2843 <term><varname>UseNTP=
</varname></term>
2844 <term><varname>UseHostname=
</varname></term>
2845 <term><varname>UseDomains=
</varname></term>
2846 <term><varname>NetLabel=
</varname></term>
2847 <term><varname>SendRelease=
</varname></term>
2849 <para>As in the [DHCPv4] section.
</para>
2851 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2856 <term><varname>NFTSet=
</varname></term>
2858 <para>This applies the NFT set for the network configuration received with DHCP, like
2859 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
2860 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal>
2861 or
<literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
2862 <literal>ipv6_addr
</literal>.
</para>
2864 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2868 <!-- How to communicate with the server -->
2871 <term><varname>WithoutRA=
</varname></term>
2873 <para>Allows DHCPv6 client to start without router advertisements's
2874 <literal>managed
</literal> or
<literal>other configuration
</literal> flag. Takes one of
2875 <literal>no
</literal>,
<literal>solicit
</literal>, or
2876 <literal>information-request
</literal>. If this is not specified,
2877 <literal>solicit
</literal> is used when
<varname>DHCPPrefixDelegation=
</varname> is enabled
2878 and
<varname>UplinkInterface=:self
</varname> is specified in the [DHCPPrefixDelegation]
2879 section. Otherwise, defaults to
<literal>no
</literal>, and the DHCPv6 client will be started
2880 when an RA is received. See also the
<varname>DHCPv6Client=
</varname> setting in the
2881 [IPv6AcceptRA] section.
</para>
2883 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2890 <title>[DHCPPrefixDelegation] Section Options
</title>
2891 <para>The [DHCPPrefixDelegation] section configures subnet prefixes of the delegated prefixes
2892 acquired by a DHCPv6 client or by a DHCPv4 client through the
6RD option on another interface.
2893 The settings in this section are used only when the
<varname>DHCPPrefixDelegation=
</varname>
2894 setting in the [Network] section is enabled.
</para>
2896 <variablelist class='network-directives'
>
2898 <term><varname>UplinkInterface=
</varname></term>
2900 <para>Specifies the name or the index of the uplink interface, or one of the special values
2901 <literal>:self
</literal> and
<literal>:auto
</literal>. When
<literal>:self
</literal>, the
2902 interface itself is considered the uplink interface, and
2903 <varname>WithoutRA=solicit
</varname> is implied if the setting is not explicitly specified.
2904 When
<literal>:auto
</literal>, the first link which acquired prefixes to be delegated from
2905 the DHCPv6 or DHCPv4 server is selected. Defaults to
<literal>:auto
</literal>.
</para>
2907 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2912 <term><varname>SubnetId=
</varname></term>
2914 <para>Configure a specific subnet ID on the interface from a (previously) received prefix
2915 delegation. You can either set
"auto" (the default) or a specific subnet ID (as defined in
2916 <ulink url=
"https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC
4291</ulink>, section
2917 2.5.4), in which case the allowed value is hexadecimal, from
0 to
0x7fffffffffffffff
2920 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2925 <term><varname>Announce=
</varname></term>
2927 <para>Takes a boolean. When enabled, and
<varname>IPv6SendRA=
</varname> in [Network] section
2928 is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
2929 This setting will be ignored when the
<varname>DHCPPrefixDelegation=
</varname> setting is
2930 enabled on the upstream interface. Defaults to yes.
</para>
2932 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
2937 <term><varname>Assign=
</varname></term>
2939 <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
2940 are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
2941 interface), the EUI-
64 algorithm will be used by default to form an interface identifier from
2942 the delegated prefixes. See also
<varname>Token=
</varname> setting below. Defaults to yes.
2945 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2950 <term><varname>Token=
</varname></term>
2952 <para>Specifies an optional address generation mode for assigning an address in each
2953 delegated prefix. This accepts the same syntax as
<varname>Token=
</varname> in the
2954 [IPv6AcceptRA] section. If
<varname>Assign=
</varname> is set to false, then this setting will
2955 be ignored. Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
2957 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2962 <term><varname>ManageTemporaryAddress=
</varname></term>
2964 <para>As in the [Address] section, but defaults to true.
</para>
2966 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2971 <term><varname>RouteMetric=
</varname></term>
2973 <para>The metric of the route to the delegated prefix subnet. Takes an unsigned integer in
2974 the range
0…
4294967295. When set to
0, the kernel's default value is used. Defaults to
256.
2977 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
2982 <term><varname>NetLabel=
</varname></term>
2984 <para>This applies the NetLabel for the addresses received with DHCP, like
2985 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
2986 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
2988 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2993 <term><varname>NFTSet=
</varname></term>
2995 <para>This applies the NFT set for the network configuration received with DHCP, like
2996 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
2997 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
2998 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
2999 <literal>ipv6_addr
</literal>.
</para>
3001 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3008 <title>[IPv6AcceptRA] Section Options
</title>
3009 <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
3010 with the
<varname>IPv6AcceptRA=
</varname> setting described above:
</para>
3012 <variablelist class='network-directives'
>
3014 <term><varname>Token=
</varname></term>
3016 <para>Specifies an optional address generation mode for the Stateless Address
3017 Autoconfiguration (SLAAC). The following values are supported:
</para>
3021 <term><option>eui64
</option></term>
3024 The EUI-
64 algorithm will be used to generate an address for that prefix. Only
3025 supported by Ethernet or InfiniBand interfaces.
3028 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3032 <term><option>static:
<replaceable>ADDRESS
</replaceable></option></term>
3035 An IPv6 address must be specified after a colon (
<literal>:
</literal>), and the
3036 lower bits of the supplied address are combined with the upper bits of a prefix
3037 received in a Router Advertisement (RA) message to form a complete address. Note
3038 that if multiple prefixes are received in an RA message, or in multiple RA messages,
3039 addresses will be formed from each of them using the supplied address. This mode
3040 implements SLAAC but uses a static interface identifier instead of an identifier
3041 generated by using the EUI-
64 algorithm. Because the interface identifier is static,
3042 if Duplicate Address Detection detects that the computed address is a duplicate
3043 (in use by another node on the link), then this mode will fail to provide an address
3044 for that prefix. If an IPv6 address without mode is specified, then
3045 <literal>static
</literal> mode is assumed.
3048 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3052 <term><option>prefixstable[:
<replaceable>ADDRESS
</replaceable>][,
<replaceable>UUID
</replaceable>]
</option></term>
3055 The algorithm specified in
3056 <ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink> will be used to
3057 generate interface identifiers. This mode can optionally take an IPv6 address
3058 separated with a colon (
<literal>:
</literal>). If an IPv6 address is specified,
3059 then an interface identifier is generated only when a prefix received in an RA
3060 message matches the supplied address.
3063 This mode can also optionally take a non-null UUID in the format which
3064 <function>sd_id128_from_string()
</function> accepts, e.g.
3065 <literal>86b123b969ba4b7eb8b3d8605123525a
</literal> or
3066 <literal>86b123b9-
69ba-
4b7e-b8b3-d8605123525a
</literal>. If a UUID is specified, the
3067 value is used as the secret key to generate interface identifiers. If not specified,
3068 then an application specific ID generated with the system's machine-ID will be used
3069 as the secret key. See
3070 <citerefentry><refentrytitle>sd-id128
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
3071 <citerefentry><refentrytitle>sd_id128_from_string
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
3073 <citerefentry><refentrytitle>sd_id128_get_machine
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
3076 Note that the
<literal>prefixstable
</literal> algorithm uses both the interface
3077 name and MAC address as input to the hash to compute the interface identifier, so
3078 if either of those are changed the resulting interface identifier (and address)
3079 will be changed, even if the prefix received in the RA message has not been
3083 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3088 <para>If no address generation mode is specified (which is the default), or a received
3089 prefix does not match any of the addresses provided in
<literal>prefixstable
</literal>
3090 mode, then the EUI-
64 algorithm will be used for Ethernet or InfiniBand interfaces,
3091 otherwise
<literal>prefixstable
</literal> will be used to form an interface identifier for
3094 <para>This setting can be specified multiple times. If an empty string is assigned, then
3095 the all previous assignments are cleared.
</para>
3098 <programlisting>Token=eui64
3100 Token=static:::
1a:
2b:
3c:
4d
3102 Token=prefixstable:
2002:da8:
1::
</programlisting></para>
3104 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3109 <term><varname>UseDNS=
</varname></term>
3111 <para>When true (the default), the DNS servers received in the Router Advertisement will be used.
</para>
3113 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
3114 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3116 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
3121 <term><varname>UseDomains=
</varname></term>
3123 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
3124 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link,
3125 similarly to the effect of the
<option>Domains=
</option> setting. If set to
3126 <literal>route
</literal>, the domain name received via IPv6 RA will be used for routing DNS queries
3127 only, but not for searching, similarly to the effect of the
<option>Domains=
</option> setting when
3128 the argument is prefixed with
<literal>~
</literal>. Defaults to false.
</para>
3130 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
3131 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
3132 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
3133 single-label names.
</para>
3135 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
3136 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3138 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
3143 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
3145 <para>The table identifier for the routes received in the Router Advertisement. Takes one of
3146 predefined names
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
3147 and names defined in
<varname>RouteTable=
</varname> in
3148 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3149 or a number between
1…
4294967295.
</para>
3151 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
3152 used when this parameter is not specified.
</para>
3154 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
3159 <term><varname>RouteMetric=
</varname></term>
3161 <para>Set the routing metric for the routes received in the Router Advertisement. Takes an unsigned
3162 integer in the range
0…
4294967295, or three unsigned integer separated with
<literal>:
</literal>,
3163 in that case the first one is used when the router preference is high, the second is for medium
3164 preference, and the last is for low preference
3165 (
<literal><replaceable>high
</replaceable>:
<replaceable>medium
</replaceable>:
<replaceable>low
</replaceable></literal>).
3166 Defaults to
<literal>512:
1024:
2048</literal>.
</para>
3168 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3173 <term><varname>QuickAck=
</varname></term>
3175 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
3176 the received RAs. When unset, the kernel's default will be used.
</para>
3178 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
3183 <term><varname>UseMTU=
</varname></term>
3185 <para>Takes a boolean. When true, the MTU received in the Router Advertisement will be
3186 used. Defaults to true.
</para>
3188 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3193 <term><varname>UseHopLimit=
</varname></term>
3195 <para>Takes a boolean. When true, the hop limit received in the Router Advertisement will be set to routes
3196 configured based on the advertisement. See also
<varname>IPv6HopLimit=
</varname>. Defaults to true.
</para>
3198 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3203 <term><varname>UseICMP6RateLimit=
</varname></term>
3205 <para>Takes a boolean. When true, the ICMP6 rate limit received in the Router Advertisement will be set to ICMP6
3206 rate limit based on the advertisement. Defaults to true.
</para>
3208 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3213 <term><varname>UseGateway=
</varname></term>
3215 <para>When true (the default), the router address will be configured as the default gateway.
3218 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3223 <term><varname>UseRoutePrefix=
</varname></term>
3225 <para>When true (the default), the routes corresponding to the route prefixes received in
3226 the Router Advertisement will be configured.
</para>
3228 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3233 <term><varname>UseCaptivePortal=
</varname></term>
3235 <para>When true (the default), the captive portal received in the Router Advertisement will be recorded
3236 and made available to client programs and displayed in the networkctl status output per-link.
</para>
3238 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
3243 <term><varname>UsePREF64=
</varname></term>
3245 <para>When true, the IPv6 PREF64 (or NAT64) prefixes received in the Router Advertisement will be recorded
3246 and made available to client programs and displayed in the
<command>networkctl
</command> status output per-link.
3247 See
<ulink url=
"https://tools.ietf.org/html/rfc8781">RFC
8781</ulink>. Defaults to false.
</para>
3249 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3254 <term><varname>UseAutonomousPrefix=
</varname></term>
3256 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
3257 precedence over any statically configured ones.
</para>
3259 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
3264 <term><varname>UseOnLinkPrefix=
</varname></term>
3266 <para>When true (the default), the onlink prefix received in the Router Advertisement will be
3267 used and takes precedence over any statically configured ones.
</para>
3269 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
3274 <term><varname>RouterDenyList=
</varname></term>
3276 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
3277 take a prefix length after
<literal>/
</literal>. Any information advertised by the listed
3278 router is ignored.
</para>
3280 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3285 <term><varname>RouterAllowList=
</varname></term>
3287 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
3288 take a prefix length after
<literal>/
</literal>. Only information advertised by the listed
3289 router is accepted. Note that if
<varname>RouterAllowList=
</varname> is configured then
3290 <varname>RouterDenyList=
</varname> is ignored.
</para>
3292 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3297 <term><varname>PrefixDenyList=
</varname></term>
3299 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
3300 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
3301 in the list are ignored.
</para>
3303 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3308 <term><varname>PrefixAllowList=
</varname></term>
3310 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
3311 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
3312 in the list are allowed. Note that if
<varname>PrefixAllowList=
</varname> is configured
3313 then
<varname>PrefixDenyList=
</varname> is ignored.
</para>
3315 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3320 <term><varname>RouteDenyList=
</varname></term>
3322 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
3323 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
3324 advertisements in the list are ignored.
</para>
3326 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3331 <term><varname>RouteAllowList=
</varname></term>
3333 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
3334 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
3335 advertisements in the list are allowed. Note that if
<varname>RouteAllowList=
</varname> is
3336 configured then
<varname>RouteDenyList=
</varname> is ignored.
</para>
3338 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3343 <term><varname>DHCPv6Client=
</varname></term>
3345 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true, the
3346 DHCPv6 client will be started in
<literal>solicit
</literal> mode if the RA has the
3347 <literal>managed
</literal> flag or
<literal>information-request
</literal> mode if the RA
3348 lacks the
<literal>managed
</literal> flag but has the
3349 <literal>other configuration
</literal> flag. If set to
<literal>always
</literal>, the
3350 DHCPv6 client will be started in
<literal>solicit
</literal> mode when an RA is received,
3351 even if neither the
<literal>managed
</literal> nor the
3352 <literal>other configuration
</literal> flag is set in the RA. This will be ignored when
3353 <varname>WithoutRA=
</varname> in the [DHCPv6] section is enabled, or
3354 <varname>UplinkInterface=:self
</varname> in the [DHCPPrefixDelegation] section is
3355 specified. Defaults to true.
</para>
3357 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3362 <term><varname>NetLabel=
</varname></term>
3364 <para>This applies the NetLabel for the addresses received with RA, like
3365 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
3366 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
3368 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
3373 <term><varname>NFTSet=
</varname></term>
3375 <para>This applies the NFT set for the network configuration received with RA, like
3376 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
3377 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
3378 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
3379 <literal>ipv6_addr
</literal>.
</para>
3381 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3388 <title>[DHCPServer] Section Options
</title>
3389 <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
3390 <varname>DHCPServer=
</varname> option described above:
</para>
3392 <variablelist class='network-directives'
>
3395 <term><varname>ServerAddress=
</varname></term>
3397 <para>Specifies the server address for the DHCP server. Takes an IPv4 address with prefix length
3398 separated with a slash, e.g.
<literal>192.168.0.1/
24</literal>. Defaults to unset, and one of
3399 static IPv4 addresses configured in [Network] or [Address] section will be automatically selected.
3400 This setting may be useful when the interface on which the DHCP server is running has multiple
3401 static IPv4 addresses.
</para>
3402 <para>This implies
<varname>Address=
</varname> in [Network] or [Address] section with the same
3403 address and prefix length. That is,
3404 <programlisting>[Network]
3406 Address=
192.168.0.1/
24
3407 Address=
192.168.0.2/
24
3409 ServerAddress=
192.168.0.1/
24</programlisting>
3411 <programlisting>[Network]
3414 Address=
192.168.0.1/
24
3416 Address=
192.168.0.2/
24
3418 ServerAddress=
192.168.0.1/
24</programlisting>
3419 are equivalent to the following.
3420 <programlisting>[Network]
3422 Address=
192.168.0.2/
24
3424 ServerAddress=
192.168.0.1/
24</programlisting>
3426 <para>Since version
255, like the
<varname>Address=
</varname> setting in [Network] or [Address]
3427 section, this also supports a null address, e.g.
<literal>0.0.0.0/
24</literal>, and an unused
3428 address will be automatically selected. For more details about the automatic address selection,
3429 see
<varname>Address=
</varname> setting in [Network] section in the above.
</para>
3431 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3436 <term><varname>PoolOffset=
</varname></term>
3437 <term><varname>PoolSize=
</varname></term>
3439 <listitem><para>Configures the pool of addresses to hand out. The pool
3440 is a contiguous sequence of IP addresses in the subnet configured for
3441 the server address, which does not include the subnet nor the broadcast
3442 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
3443 from the start of subnet, or zero to use the default value.
3444 <varname>PoolSize=
</varname> takes the number of IP addresses in the
3445 pool or zero to use the default value. By default, the pool starts at
3446 the first address after the subnet address and takes up the rest of
3447 the subnet, excluding the broadcast address. If the pool includes
3448 the server address (the default), this is reserved and not handed
3449 out to clients.
</para>
3451 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3455 <term><varname>DefaultLeaseTimeSec=
</varname></term>
3456 <term><varname>MaxLeaseTimeSec=
</varname></term>
3458 <listitem><para>Control the default and maximum DHCP lease
3459 time to pass to clients. These settings take time values in seconds or
3460 another common time unit, depending on the suffix. The default
3461 lease time is used for clients that did not ask for a specific
3462 lease time. If a client asks for a lease time longer than the
3463 maximum lease time, it is automatically shortened to the
3464 specified time. The default lease time defaults to
1h, the
3465 maximum lease time to
12h. Shorter lease times are beneficial
3466 if the configuration data in DHCP leases changes frequently
3467 and clients shall learn the new settings with shorter
3468 latencies. Longer lease times reduce the generated DHCP
3469 network traffic.
</para>
3471 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3475 <term><varname>UplinkInterface=
</varname></term>
3476 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
3477 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS, NTP, or SIP
3478 servers is enabled but no servers are specified, the servers configured in the uplink interface
3479 will be emitted. When
<literal>:auto
</literal>, the link which has a default gateway with the
3480 highest priority will be automatically selected. When
<literal>:none
</literal>, no uplink
3481 interface will be selected. Defaults to
<literal>:auto
</literal>.
</para>
3483 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3487 <term><varname>EmitDNS=
</varname></term>
3488 <term><varname>DNS=
</varname></term>
3490 <listitem><para><varname>EmitDNS=
</varname> takes a boolean. Configures whether the DHCP leases
3491 handed out to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
3492 The DNS servers to pass to clients may be configured with the
<varname>DNS=
</varname> option,
3493 which takes a list of IPv4 addresses, or special value
<literal>_server_address
</literal> which
3494 will be converted to the address used by the DHCP server.
</para>
3496 <para>If the
<varname>EmitDNS=
</varname> option is enabled but no servers configured, the
3497 servers are automatically propagated from an
"uplink" interface that has appropriate servers
3498 set. The
"uplink" interface is determined by the default route of the system with the highest
3499 priority. Note that this information is acquired at the time the lease is handed out, and does
3500 not take uplink interfaces into account that acquire DNS server information at a later point.
3501 If no suitable uplink interface is found the DNS server data from
3502 <filename>/etc/resolv.conf
</filename> is used. Also, note that the leases are not refreshed if
3503 the uplink network configuration changes. To ensure clients regularly acquire the most current
3504 uplink DNS server information, it is thus advisable to shorten the DHCP lease time via
3505 <varname>MaxLeaseTimeSec=
</varname> described above.
</para>
3507 <para>This setting can be specified multiple times. If an empty string is specified, then all
3508 DNS servers specified earlier are cleared.
</para>
3510 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3514 <term><varname>EmitNTP=
</varname></term>
3515 <term><varname>NTP=
</varname></term>
3516 <term><varname>EmitSIP=
</varname></term>
3517 <term><varname>SIP=
</varname></term>
3518 <term><varname>EmitPOP3=
</varname></term>
3519 <term><varname>POP3=
</varname></term>
3520 <term><varname>EmitSMTP=
</varname></term>
3521 <term><varname>SMTP=
</varname></term>
3522 <term><varname>EmitLPR=
</varname></term>
3523 <term><varname>LPR=
</varname></term>
3525 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname> settings
3526 described above, these settings configure whether and what server information for the indicate
3527 protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
3528 defaults apply as for
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname>.
</para>
3530 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3534 <term><varname>EmitRouter=
</varname></term>
3535 <term><varname>Router=
</varname></term>
3537 <listitem><para>The
<varname>EmitRouter=
</varname> setting takes a boolean value, and configures
3538 whether the DHCP lease should contain the router option. The
<varname>Router=
</varname> setting
3539 takes an IPv4 address, and configures the router address to be emitted. When the
3540 <varname>Router=
</varname> setting is not specified, then the server address will be used for
3541 the router option. When the
<varname>EmitRouter=
</varname> setting is disabled, the
3542 <varname>Router=
</varname> setting will be ignored. The
<varname>EmitRouter=
</varname> setting
3543 defaults to true, and the
<varname>Router=
</varname> setting defaults to unset.
3546 <xi:include href=
"version-info.xml" xpointer=
"v230"/></listitem>
3550 <term><varname>EmitTimezone=
</varname></term>
3551 <term><varname>Timezone=
</varname></term>
3553 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
3554 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
3555 <varname>Timezone=
</varname> setting takes a timezone string
3556 (such as
<literal>Europe/Berlin
</literal> or
3557 <literal>UTC
</literal>) to pass to clients. If no explicit
3558 timezone is set, the system timezone of the local host is
3559 propagated, as determined by the
3560 <filename>/etc/localtime
</filename> symlink.
</para>
3562 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3566 <term><varname>BootServerAddress=
</varname></term>
3569 <para>Takes an IPv4 address of the boot server used by e.g. PXE boot systems. When specified, this
3570 address is sent in the
<option>siaddr
</option> field of the DHCP message header. See
<ulink
3571 url=
"https://www.rfc-editor.org/rfc/rfc2131.html">RFC
2131</ulink> for more details. Defaults to
3574 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3579 <term><varname>BootServerName=
</varname></term>
3582 <para>Takes a name of the boot server used by e.g. PXE boot systems. When specified, this name is
3583 sent in the DHCP option
66 (
"TFTP server name"). See
<ulink
3584 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
3587 <para>Note that typically setting one of
<varname>BootServerName=
</varname> or
3588 <varname>BootServerAddress=
</varname> is sufficient, but both can be set too, if desired.
</para>
3590 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3595 <term><varname>BootFilename=
</varname></term>
3598 <para>Takes a path or URL to a file loaded by e.g. a PXE boot loader. When specified, this path is
3599 sent in the DHCP option
67 (
"Bootfile name"). See
<ulink
3600 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
3603 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3608 <term><varname>IPv6OnlyPreferredSec=
</varname></term>
3611 <para>Takes a timespan. Controls the
3612 <ulink url=
"https://tools.ietf.org/html/rfc8925">RFC
8925</ulink> IPv6-Only Preferred option.
3613 Specifies the DHCPv4 option to indicate that a host supports an IPv6-only mode and is willing to
3614 forgo obtaining an IPv4 address if the network provides IPv6 connectivity. Defaults to unset, and
3615 not send the option. The minimum allowed value is
300 seconds.
</para>
3617 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3622 <term><varname>SendOption=
</varname></term>
3624 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
3625 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
3626 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
3627 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
3628 <literal>string
</literal>. Special characters in the data string may be escaped using
3629 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
3630 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
3631 then all options specified earlier are cleared. Defaults to unset.
</para>
3633 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
3638 <term><varname>SendVendorOption=
</varname></term>
3640 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
3641 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
3642 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
3643 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
3644 <literal>string
</literal>. Special characters in the data string may be escaped using
3645 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
3646 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
3647 then all options specified earlier are cleared. Defaults to unset.
</para>
3649 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3653 <term><varname>BindToInterface=
</varname></term>
3655 <para>Takes a boolean value. When
<literal>yes
</literal>, DHCP server socket will be bound
3656 to its network interface and all socket communication will be restricted to this interface.
3657 Defaults to
<literal>yes
</literal>, except if
<varname>RelayTarget=
</varname> is used (see below),
3658 in which case it defaults to
<literal>no
</literal>.
</para>
3660 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3664 <term><varname>RelayTarget=
</varname></term>
3666 <para>Takes an IPv4 address, which must be in the format described in
3667 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
3668 Turns this DHCP server into a DHCP relay agent. See
<ulink url=
"https://tools.ietf.org/html/rfc1542">RFC
1542</ulink>.
3669 The address is the address of DHCP server or another relay agent to forward DHCP messages to and from.
</para>
3671 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3675 <term><varname>RelayAgentCircuitId=
</varname></term>
3677 <para>Specifies value for Agent Circuit ID suboption of Relay Agent Information option.
3678 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
3679 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
3680 Defaults to unset (means no Agent Circuit ID suboption is generated).
3681 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3683 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3687 <term><varname>RelayAgentRemoteId=
</varname></term>
3689 <para>Specifies value for Agent Remote ID suboption of Relay Agent Information option.
3690 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
3691 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
3692 Defaults to unset (means no Agent Remote ID suboption is generated).
3693 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3695 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3703 <title>[DHCPServerStaticLease] Section Options
</title>
3704 <para>The
<literal>[DHCPServerStaticLease]
</literal> section configures a static DHCP lease to assign a
3705 fixed IPv4 address to a specific device based on its MAC address. This section can be specified multiple
3708 <variablelist class='network-directives'
>
3710 <term><varname>MACAddress=
</varname></term>
3712 <listitem><para>The hardware address of a device to match. This key is mandatory.
</para>
3714 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3718 <term><varname>Address=
</varname></term>
3720 <listitem><para>The IPv4 address that should be assigned to the device that was matched with
3721 <varname>MACAddress=
</varname>. This key is mandatory.
</para>
3723 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3729 <title>[IPv6SendRA] Section Options
</title>
3730 <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
3731 to act as a router, if enabled via the
<varname>IPv6SendRA=
</varname> option described above. IPv6
3732 network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
3735 <variablelist class='network-directives'
>
3738 <term><varname>Managed=
</varname></term>
3739 <term><varname>OtherInformation=
</varname></term>
3741 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
3742 addresses on the network link when
<varname>Managed=
</varname>
3743 is set to
<literal>true
</literal> or if only additional network
3744 information can be obtained via DHCPv6 for the network link when
3745 <varname>OtherInformation=
</varname> is set to
3746 <literal>true
</literal>. Both settings default to
3747 <literal>false
</literal>, which means that a DHCPv6 server is not being
3750 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3754 <term><varname>RouterLifetimeSec=
</varname></term>
3756 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. The value must be
0
3757 seconds, or between
4 seconds and
9000 seconds. When set to
0, the host is not acting as a router.
3758 Defaults to
1800 seconds (
30 minutes).
</para>
3760 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
3765 <term><varname>RetransmitSec=
</varname></term>
3767 <listitem><para>Takes a timespan. Configures the retransmit time, used by clients to retransmit Neighbor
3768 Solicitation messages on address resolution and the Neighbor Unreachability Detection algorithm.
3769 An integer the default unit of seconds, in the range
0…
4294967295 msec. Defaults to
0.
</para>
3771 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3776 <term><varname>RouterPreference=
</varname></term>
3778 <listitem><para>Configures IPv6 router preference if
3779 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
3780 <literal>high
</literal>,
<literal>medium
</literal> and
3781 <literal>low
</literal>, with
<literal>normal
</literal> and
3782 <literal>default
</literal> added as synonyms for
3783 <literal>medium
</literal> just to make configuration easier. See
3784 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
3785 for details. Defaults to
<literal>medium
</literal>.
</para>
3787 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3791 <term><varname>HopLimit=
</varname></term>
3793 <para>Configures hop limit. Takes an integer in the range
0…
255. See also
3794 <varname>IPv6HopLimit=
</varname>.
</para>
3796 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3801 <term><varname>UplinkInterface=
</varname></term>
3802 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
3803 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS servers or
3804 search domains is enabled but no servers are specified, the servers configured in the uplink
3805 interface will be emitted. When
<literal>:auto
</literal>, the value specified to the same
3806 setting in the [DHCPPrefixDelegation] section will be used if
3807 <varname>DHCPPrefixDelegation=
</varname> is enabled, otherwise the link which has a default
3808 gateway with the highest priority will be automatically selected. When
<literal>:none
</literal>,
3809 no uplink interface will be selected. Defaults to
<literal>:auto
</literal>.
</para>
3811 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
3815 <term><varname>EmitDNS=
</varname></term>
3816 <term><varname>DNS=
</varname></term>
3818 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
3819 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is true.
3820 <varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that case
3821 the IPv6 link-local address is distributed. If
<varname>DNS=
</varname> is empty, DNS servers are
3822 read from the [Network] section. If the [Network] section does not contain any DNS servers
3823 either, DNS servers from the uplink interface specified in
<varname>UplinkInterface=
</varname>
3824 will be used. When
<varname>EmitDNS=
</varname> is false, no DNS server information is sent in
3825 Router Advertisement messages.
<varname>EmitDNS=
</varname> defaults to true.
</para>
3827 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3831 <term><varname>EmitDomains=
</varname></term>
3832 <term><varname>Domains=
</varname></term>
3834 <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
3835 <varname>EmitDomains=
</varname> is true. If
<varname>Domains=
</varname> is empty, DNS search
3836 domains are read from the [Network] section. If the [Network] section does not contain any DNS
3837 search domains either, DNS search domains from the uplink interface specified in
3838 <varname>UplinkInterface=
</varname> will be used. When
<varname>EmitDomains=
</varname> is false,
3839 no DNS search domain information is sent in Router Advertisement messages.
3840 <varname>EmitDomains=
</varname> defaults to true.
</para>
3842 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3846 <term><varname>DNSLifetimeSec=
</varname></term>
3848 <listitem><para>Lifetime in seconds for the DNS server addresses listed in
3849 <varname>DNS=
</varname> and search domains listed in
<varname>Domains=
</varname>. Defaults to
3850 3600 seconds (one hour).
</para>
3852 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3856 <term><varname>HomeAgent=
</varname></term>
3858 <listitem><para>Takes a boolean. Specifies that IPv6 router advertisements which indicates to hosts that
3859 the router acts as a Home Agent and includes a Home Agent Option. Defaults to false. See
3860 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink> for further details.
</para>
3862 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3867 <term><varname>HomeAgentLifetimeSec=
</varname></term>
3869 <listitem><para>Takes a timespan. Specifies the lifetime of the Home Agent. An integer the default unit of seconds,
3870 in the range
1…
65535. Defaults to the value set to
<varname>RouterLifetimeSec=
</varname>.
</para>
3872 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3877 <term><varname>HomeAgentPreference=
</varname></term>
3879 <listitem><para>Configures IPv6 Home Agent preference. Takes an integer in the range
0…
65535.
3880 Defaults to
0.
</para>
3882 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3890 <title>[IPv6Prefix] Section Options
</title>
3891 <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
3892 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink> for further
3895 <variablelist class='network-directives'
>
3898 <term><varname>AddressAutoconfiguration=
</varname></term>
3899 <term><varname>OnLink=
</varname></term>
3901 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
3902 autoconfigured with this prefix and whether the prefix can be used for
3903 onlink determination. Both settings default to
<literal>true
</literal>
3904 in order to ease configuration.
3907 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3911 <term><varname>Prefix=
</varname></term>
3913 <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
3914 IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
3915 <literal>/
</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
3916 prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
3917 prefix to another.
</para>
3919 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3923 <term><varname>PreferredLifetimeSec=
</varname></term>
3924 <term><varname>ValidLifetimeSec=
</varname></term>
3926 <listitem><para>Preferred and valid lifetimes for the prefix measured in seconds.
3927 <varname>PreferredLifetimeSec=
</varname> defaults to
1800 seconds (
30 minutes) and
3928 <varname>ValidLifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para>
3930 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3934 <term><varname>Assign=
</varname></term>
3935 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
3938 <xi:include href=
"version-info.xml" xpointer=
"v246"/></listitem>
3942 <term><varname>Token=
</varname></term>
3944 <para>Specifies an optional address generation mode for assigning an address in each
3945 prefix. This accepts the same syntax as
<varname>Token=
</varname> in the [IPv6AcceptRA]
3946 section. If
<varname>Assign=
</varname> is set to false, then this setting will be ignored.
3947 Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
3949 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3954 <term><varname>RouteMetric=
</varname></term>
3956 <para>The metric of the prefix route. Takes an unsigned integer in the range
0…
4294967295.
3957 When unset or set to
0, the kernel's default value is used. This setting is ignored when
3958 <varname>Assign=
</varname> is false.
</para>
3960 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3967 <title>[IPv6RoutePrefix] Section Options
</title>
3968 <para>One or more [IPv6RoutePrefix] sections contain the IPv6
3969 prefix routes that are announced via Router Advertisements. See
3970 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
3971 for further details.
</para>
3973 <variablelist class='network-directives'
>
3976 <term><varname>Route=
</varname></term>
3978 <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
3979 IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
3980 separated by a
<literal>/
</literal> character. Use multiple [IPv6RoutePrefix] sections to configure
3981 multiple IPv6 prefix routes.
</para>
3983 <xi:include href=
"version-info.xml" xpointer=
"v244"/></listitem>
3987 <term><varname>LifetimeSec=
</varname></term>
3989 <listitem><para>Lifetime for the route prefix measured in seconds.
3990 <varname>LifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para>
3992 <xi:include href=
"version-info.xml" xpointer=
"v244"/></listitem>
3999 <title>[IPv6PREF64Prefix] Section Options
</title>
4000 <para>One or more [IPv6PREF64Prefix] sections contain the IPv6 PREF64 (or NAT64) prefixes that are announced via Router
4001 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc8781">RFC
8781</ulink> for further
4004 <variablelist class='network-directives'
>
4007 <term><varname>Prefix=
</varname></term>
4009 <listitem><para>The IPv6 PREF64 (or NAT64) prefix that is to be distributed to hosts. The setting holds
4010 an IPv6 prefix that should be set up for NAT64 translation (PLAT) to allow
464XLAT on the network segment.
4011 Use multiple [IPv6PREF64Prefix] sections to configure multiple IPv6 prefixes since prefix lifetime may differ
4012 from one prefix to another. The prefix is an address with a prefix length, separated by a slash
4013 <literal>/
</literal> character. Valid NAT64 prefix length are
96,
64,
56,
48,
40, and
32 bits.
</para>
4015 <xi:include href=
"version-info.xml" xpointer=
"v255"/></listitem></varlistentry>
4018 <term><varname>LifetimeSec=
</varname></term>
4019 <listitem><para>Lifetime for the prefix measured in seconds. Should be greater than or equal to
<varname>RouterLifetimeSec=
</varname>.
4020 <varname>LifetimeSec=
</varname> defaults to
1800 seconds.
</para>
4022 <xi:include href=
"version-info.xml" xpointer=
"v255"/></listitem>
4028 <title>[Bridge] Section Options
</title>
4029 <para>The [Bridge] section accepts the following keys:
</para>
4030 <variablelist class='network-directives'
>
4032 <term><varname>UnicastFlood=
</varname></term>
4034 <para>Takes a boolean. Controls whether the bridge should flood
4035 traffic for which an FDB entry is missing and the destination
4036 is unknown through this port. When unset, the kernel's default will be used.
4039 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4043 <term><varname>MulticastFlood=
</varname></term>
4045 <para>Takes a boolean. Controls whether the bridge should flood
4046 traffic for which an MDB entry is missing and the destination
4047 is unknown through this port. When unset, the kernel's default will be used.
4050 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4054 <term><varname>MulticastToUnicast=
</varname></term>
4056 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
4057 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
4058 When unset, the kernel's default will be used.
4061 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
4065 <term><varname>NeighborSuppression=
</varname></term>
4067 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
4068 this port. When unset, the kernel's default will be used.
4071 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4075 <term><varname>Learning=
</varname></term>
4077 <para>Takes a boolean. Configures whether MAC address learning is enabled for
4078 this port. When unset, the kernel's default will be used.
4081 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4085 <term><varname>HairPin=
</varname></term>
4087 <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
4088 was received. When this flag is false, then the bridge will not forward traffic back out of the
4089 receiving port. When unset, the kernel's default will be used.
</para>
4091 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4095 <term><varname>Isolated=
</varname></term>
4097 <para>Takes a boolean. Configures whether this port is isolated or not. Within a bridge,
4098 isolated ports can only communicate with non-isolated ports. When set to true, this port can only
4099 communicate with other ports whose Isolated setting is false. When set to false, this port
4100 can communicate with any other ports. When unset, the kernel's default will be used.
</para>
4102 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
4106 <term><varname>UseBPDU=
</varname></term>
4108 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
4109 processed by the bridge port. When unset, the kernel's default will be used.
</para>
4111 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4115 <term><varname>FastLeave=
</varname></term>
4117 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
4118 traffic on a port that receives an IGMP Leave message. It is only used with
4119 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
4121 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4125 <term><varname>AllowPortToBeRoot=
</varname></term>
4127 <para>Takes a boolean. Configures whether a given port is allowed to
4128 become a root port. Only used when STP is enabled on the bridge.
4129 When unset, the kernel's default will be used.
</para>
4131 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4135 <term><varname>ProxyARP=
</varname></term>
4137 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
4138 When unset, the kernel's default will be used.
</para>
4140 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4144 <term><varname>ProxyARPWiFi=
</varname></term>
4146 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
4147 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
4148 When unset, the kernel's default will be used.
</para>
4150 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4154 <term><varname>MulticastRouter=
</varname></term>
4156 <para>Configures this port for having multicast routers attached. A port with a multicast
4157 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
4158 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
4159 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
4160 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
4161 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
4163 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4167 <term><varname>Cost=
</varname></term>
4169 <para>Sets the
"cost" of sending packets of this interface.
4170 Each port in a bridge may have a different speed and the cost
4171 is used to decide which link to use. Faster interfaces
4172 should have lower costs. It is an integer value between
1 and
4175 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
4179 <term><varname>Priority=
</varname></term>
4181 <para>Sets the
"priority" of sending packets on this interface.
4182 Each port in a bridge may have a different priority which is used
4183 to decide which link to use. Lower value means higher priority.
4184 It is an integer value between
0 to
63. Networkd does not set any
4185 default, meaning the kernel default value of
32 is used.
</para>
4187 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
4193 <title>[BridgeFDB] Section Options
</title>
4194 <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
4195 keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.
</para>
4197 <variablelist class='network-directives'
>
4199 <term><varname>MACAddress=
</varname></term>
4201 <para>As in the [Network] section. This key is mandatory.
</para>
4203 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
4207 <term><varname>Destination=
</varname></term>
4209 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
4211 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4215 <term><varname>VLANId=
</varname></term>
4217 <para>The VLAN ID for the new static MAC table entry. If
4218 omitted, no VLAN ID information is appended to the new static MAC
4221 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
4225 <term><varname>VNI=
</varname></term>
4227 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
4228 the remote VXLAN tunnel endpoint. Takes a number in the range
1…
16777215.
4229 Defaults to unset.
</para>
4231 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4235 <term><varname>AssociatedWith=
</varname></term>
4237 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
4238 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
4239 <literal>use
</literal> means the address is in use. User space can use this option to
4240 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
4241 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
4242 means the address is associated with master devices fdb.
<literal>router
</literal> means
4243 the destination address is associated with a router. Note that it's valid if the referenced
4244 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
4246 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4250 <term><varname>OutgoingInterface=
</varname></term>
4252 <para>Specifies the name or index of the outgoing interface for the VXLAN device driver to
4253 reach the remote VXLAN tunnel endpoint. Defaults to unset.
</para>
4255 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
4261 <title>[BridgeMDB] Section Options
</title>
4262 <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
4263 keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.
</para>
4265 <variablelist class='network-directives'
>
4267 <term><varname>MulticastGroupAddress=
</varname></term>
4269 <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.
</para>
4271 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4275 <term><varname>VLANId=
</varname></term>
4277 <para>The VLAN ID for the new entry. Valid ranges are
0 (no VLAN) to
4094. Optional, defaults to
0.
</para>
4279 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4286 <title>[LLDP] Section Options
</title>
4287 <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
4289 <variablelist class='network-directives'
>
4291 <term><varname>MUDURL=
</varname></term>
4293 <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
4294 LLDP packets. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
4295 [DHCPv4] section described above.
</para>
4297 <para>The MUD URLs received via LLDP packets are saved and can be read using the
4298 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
4300 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4307 <title>[CAN] Section Options
</title>
4308 <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
4309 following keys:
</para>
4310 <variablelist class='network-directives'
>
4312 <term><varname>BitRate=
</varname></term>
4314 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
4315 be used here. Takes a number in the range
1…
4294967295.
</para>
4317 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4321 <term><varname>SamplePoint=
</varname></term>
4323 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
4324 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>). This will be ignored when
4325 <varname>BitRate=
</varname> is unspecified.
</para>
4327 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4331 <term><varname>TimeQuantaNSec=
</varname></term>
4332 <term><varname>PropagationSegment=
</varname></term>
4333 <term><varname>PhaseBufferSegment1=
</varname></term>
4334 <term><varname>PhaseBufferSegment2=
</varname></term>
4335 <term><varname>SyncJumpWidth=
</varname></term>
4337 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
4338 synchronization jump width, which allow one to define the CAN bit-timing in a hardware
4339 independent format as proposed by the Bosch CAN
2.0 Specification.
4340 <varname>TimeQuantaNSec=
</varname> takes a timespan in nanoseconds.
4341 <varname>PropagationSegment=
</varname>,
<varname>PhaseBufferSegment1=
</varname>,
4342 <varname>PhaseBufferSegment2=
</varname>, and
<varname>SyncJumpWidth=
</varname> take number
4343 of time quantum specified in
<varname>TimeQuantaNSec=
</varname> and must be an unsigned
4344 integer in the range
0…
4294967295. These settings except for
4345 <varname>SyncJumpWidth=
</varname> will be ignored when
<varname>BitRate=
</varname> is
4348 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4352 <term><varname>DataBitRate=
</varname></term>
4353 <term><varname>DataSamplePoint=
</varname></term>
4355 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
4356 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
4358 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4362 <term><varname>DataTimeQuantaNSec=
</varname></term>
4363 <term><varname>DataPropagationSegment=
</varname></term>
4364 <term><varname>DataPhaseBufferSegment1=
</varname></term>
4365 <term><varname>DataPhaseBufferSegment2=
</varname></term>
4366 <term><varname>DataSyncJumpWidth=
</varname></term>
4368 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
4369 synchronization jump width for the data phase, if CAN-FD is used. These settings are
4370 analogous to the
<varname>TimeQuantaNSec=
</varname> or related settings.
</para>
4372 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4376 <term><varname>FDMode=
</varname></term>
4378 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
4379 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
4380 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys, or
4381 <varname>DataTimeQuanta=
</varname> and related settings.
</para>
4383 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4387 <term><varname>FDNonISO=
</varname></term>
4389 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
4390 interface. When unset, the kernel's default will be used.
</para>
4392 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4396 <term><varname>RestartSec=
</varname></term>
4398 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
4399 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
4400 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
4401 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
4402 automatic restart off. By default automatic restart is disabled.
</para>
4404 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4408 <term><varname>Termination=
</varname></term>
4410 <para>Takes a boolean or a termination resistor value in ohm in the range
0…
65535. When
4411 <literal>yes
</literal>, the termination resistor is set to
120 ohm. When
4412 <literal>no
</literal> or
<literal>0</literal> is set, the termination resistor is disabled.
4413 When unset, the kernel's default will be used.
</para>
4415 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4419 <term><varname>TripleSampling=
</varname></term>
4421 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
4422 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
4424 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4428 <term><varname>BusErrorReporting=
</varname></term>
4430 <para>Takes a boolean. When
<literal>yes
</literal>, reporting of CAN bus errors is activated
4431 (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
4432 unable to send recessive bit, bus overload, active error announcement, error occurred on
4433 transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
4434 single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.
</para>
4436 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
4440 <term><varname>ListenOnly=
</varname></term>
4442 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
4443 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
4444 bit. Listen-only mode is important to debug CAN networks without interfering with the
4445 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
4448 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4452 <term><varname>Loopback=
</varname></term>
4454 <para>Takes a boolean. When
<literal>yes
</literal>, loopback mode is enabled. When the
4455 loopback mode is enabled, the interface treats messages transmitted by itself as received
4456 messages. The loopback mode is important to debug CAN networks. When unset, the kernel's
4457 default will be used.
</para>
4459 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4463 <term><varname>OneShot=
</varname></term>
4465 <para>Takes a boolean. When
<literal>yes
</literal>, one-shot mode is enabled. When unset,
4466 the kernel's default will be used.
</para>
4468 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4472 <term><varname>PresumeAck=
</varname></term>
4474 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will ignore missing CAN
4475 ACKs. When unset, the kernel's default will be used.
</para>
4477 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4481 <term><varname>ClassicDataLengthCode=
</varname></term>
4483 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will handle the
4bit data
4484 length code (DLC). When unset, the kernel's default will be used.
</para>
4486 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4493 <title>[IPoIB] Section Options
</title>
4494 <para>The [IPoIB] section manages the IP over Infiniband and accepts the following keys:
</para>
4495 <variablelist class='network-directives'
>
4496 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_mode" />
4497 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_umcast" />
4502 <title>[QDisc] Section Options
</title>
4503 <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).
</para>
4505 <variablelist class='network-directives'
>
4507 <term><varname>Parent=
</varname></term>
4509 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
4510 or
<literal>ingress
</literal>. This is mandatory.
</para>
4512 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
4516 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4521 <title>[NetworkEmulator] Section Options
</title>
4522 <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
4523 can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
4524 applications, or limit the bandwidth usage of a particular service to simulate internet connections.
4527 <variablelist class='network-directives'
>
4528 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4529 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4532 <term><varname>DelaySec=
</varname></term>
4534 <para>Specifies the fixed amount of delay to be added to all packets going out of the
4535 interface. Defaults to unset.
</para>
4537 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4542 <term><varname>DelayJitterSec=
</varname></term>
4544 <para>Specifies the chosen delay to be added to the packets outgoing to the network
4545 interface. Defaults to unset.
</para>
4547 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4552 <term><varname>PacketLimit=
</varname></term>
4554 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
4555 An unsigned integer in the range
0…
4294967294. Defaults to
1000.
</para>
4557 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4562 <term><varname>LossRate=
</varname></term>
4564 <para>Specifies an independent loss probability to be added to the packets outgoing from the
4565 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
4567 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4572 <term><varname>DuplicateRate=
</varname></term>
4574 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
4575 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
4577 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4584 <title>[TokenBucketFilter] Section Options
</title>
4585 <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
4588 <variablelist class='network-directives'
>
4589 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4590 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4593 <term><varname>LatencySec=
</varname></term>
4595 <para>Specifies the latency parameter, which specifies the maximum amount of time a
4596 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
4598 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4603 <term><varname>LimitBytes=
</varname></term>
4605 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
4606 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
4607 respectively, to the base of
1024. Defaults to unset.
</para>
4609 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4614 <term><varname>BurstBytes=
</varname></term>
4616 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
4617 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
4618 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to
4621 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4626 <term><varname>Rate=
</varname></term>
4628 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
4629 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
4630 Defaults to unset.
</para>
4632 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4637 <term><varname>MPUBytes=
</varname></term>
4639 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
4640 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
4641 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to zero.
</para>
4643 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4648 <term><varname>PeakRate=
</varname></term>
4650 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
4651 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
4652 1000. Defaults to unset.
</para>
4654 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4659 <term><varname>MTUBytes=
</varname></term>
4661 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
4662 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
4663 Defaults to unset.
</para>
4665 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4672 <title>[PIE] Section Options
</title>
4673 <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
4674 controller-Enhanced (PIE).
</para>
4676 <variablelist class='network-directives'
>
4677 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4678 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4681 <term><varname>PacketLimit=
</varname></term>
4683 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4684 incoming packets are dropped. An unsigned integer in the range
1…
4294967294. Defaults to unset and
4685 kernel's default is used.
</para>
4687 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4694 <title>[FlowQueuePIE] Section Options
</title>
4695 <para>The
<literal>[FlowQueuePIE]
</literal> section manages the queueing discipline
4696 (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).
</para>
4698 <variablelist class='network-directives'
>
4699 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4700 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4703 <term><varname>PacketLimit=
</varname></term>
4705 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4706 incoming packets are dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and
4707 kernel's default is used.
</para>
4709 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4716 <title>[StochasticFairBlue] Section Options
</title>
4717 <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
4720 <variablelist class='network-directives'
>
4721 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4722 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4725 <term><varname>PacketLimit=
</varname></term>
4727 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4728 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
4729 kernel's default is used.
</para>
4731 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4738 <title>[StochasticFairnessQueueing] Section Options
</title>
4739 <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
4740 fairness queueing (sfq).
</para>
4742 <variablelist class='network-directives'
>
4743 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4744 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4747 <term><varname>PerturbPeriodSec=
</varname></term>
4749 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
4751 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4758 <title>[BFIFO] Section Options
</title>
4759 <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
4762 <variablelist class='network-directives'
>
4763 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4764 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4767 <term><varname>LimitBytes=
</varname></term>
4769 <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
4770 in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
4771 reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
4772 as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
4773 kernel default is used.
</para>
4775 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4782 <title>[PFIFO] Section Options
</title>
4783 <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
4786 <variablelist class='network-directives'
>
4787 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4788 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4791 <term><varname>PacketLimit=
</varname></term>
4793 <para>Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents
4794 overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this
4795 limit is reached, incoming packets are dropped. An unsigned integer in the range
4796 0…
4294967294. Defaults to unset and kernel's default is used.
</para>
4798 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4805 <title>[PFIFOHeadDrop] Section Options
</title>
4806 <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
4807 Head Drop (pfifo_head_drop).
</para>
4809 <variablelist class='network-directives'
>
4810 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4811 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4814 <term><varname>PacketLimit=
</varname></term>
4816 <para>As in [PFIFO] section.
</para>
4818 <xi:include href=
"version-info.xml" xpointer=
"v246"/></listitem>
4824 <title>[PFIFOFast] Section Options
</title>
4825 <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
4826 (pfifo_fast).
</para>
4828 <variablelist class='network-directives'
>
4829 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4830 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4835 <title>[CAKE] Section Options
</title>
4836 <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
4839 <variablelist class='network-directives'
>
4840 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4841 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4844 <term><varname>Bandwidth=
</varname></term>
4846 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
4847 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
4848 unset and kernel's default is used.
</para>
4850 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4855 <term><varname>AutoRateIngress=
</varname></term>
4857 <para>Takes a boolean value. Enables automatic capacity estimation based on traffic arriving
4858 at this qdisc. This is most likely to be useful with cellular links, which tend to change
4859 quality randomly. If this setting is enabled, the
<varname>Bandwidth=
</varname> setting is
4860 used as an initial estimate. Defaults to unset, and the kernel's default is used.
</para>
4862 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4867 <term><varname>OverheadBytes=
</varname></term>
4869 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative.
4870 Takes an integer in the range -
64…
256. Defaults to unset and kernel's default is used.
4873 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4878 <term><varname>MPUBytes=
</varname></term>
4880 <para>Rounds each packet (including overhead) up to the specified bytes. Takes an integer in
4881 the range
1…
256. Defaults to unset and kernel's default is used.
</para>
4883 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4888 <term><varname>CompensationMode=
</varname></term>
4890 <para>Takes one of
<literal>none
</literal>,
<literal>atm
</literal>, or
<literal>ptm
</literal>.
4891 Specifies the compensation mode for overhead calculation. When
<literal>none
</literal>, no
4892 compensation is taken into account. When
<literal>atm
</literal>, enables the compensation for
4893 ATM cell framing, which is normally found on ADSL links. When
<literal>ptm
</literal>, enables
4894 the compensation for PTM encoding, which is normally found on VDSL2 links and uses a
64b/
65b
4895 encoding scheme. Defaults to unset and the kernel's default is used.
</para>
4897 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4902 <term><varname>UseRawPacketSize=
</varname></term>
4904 <para>Takes a boolean value. When true, the packet size reported by the Linux kernel will be
4905 used, instead of the underlying IP packet size. Defaults to unset, and the kernel's default
4908 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4913 <term><varname>FlowIsolationMode=
</varname></term>
4915 <para>CAKE places packets from different flows into different queues, then packets from each
4916 queue are delivered fairly. This specifies whether the fairness is based on source address,
4917 destination address, individual flows, or any combination of those. The available values are:
4922 <term><option>none
</option></term>
4924 The flow isolation is disabled, and all traffic passes through a single queue.
4927 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
4930 <term><option>src-host
</option></term>
4932 Flows are defined only by source address. Equivalent to the
<literal>srchost
</literal>
4933 option for
<command>tc qdisc
</command> command. See also
4934 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4937 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
4940 <term><option>dst-host
</option></term>
4942 Flows are defined only by destination address. Equivalent to the
4943 <literal>dsthost
</literal> option for
<command>tc qdisc
</command> command. See also
4944 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4947 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
4950 <term><option>hosts
</option></term>
4952 Flows are defined by source-destination host pairs. Equivalent to the same option for
4953 <command>tc qdisc
</command> command. See also
4954 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4957 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
4960 <term><option>flows
</option></term>
4962 Flows are defined by the entire
5-tuple of source address, destination address,
4963 transport protocol, source port and destination port. Equivalent to the same option for
4964 <command>tc qdisc
</command> command. See also
4965 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4968 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
4971 <term><option>dual-src-host
</option></term>
4973 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
4974 fairness is applied first over source addresses, then over individual flows. Equivalent
4975 to the
<literal>dual-srchost
</literal> option for
<command>tc qdisc
</command> command.
4977 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4980 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
4983 <term><option>dual-dst-host
</option></term>
4985 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
4986 fairness is applied first over destination addresses, then over individual flows.
4987 Equivalent to the
<literal>dual-dsthost
</literal> option for
4988 <command>tc qdisc
</command> command. See also
4989 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4992 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
4995 <term><option>triple
</option></term>
4997 Flows are defined by the
5-tuple (see
<literal>flows
</literal>), and fairness is
4998 applied over source and destination addresses, and also over individual flows.
4999 Equivalent to the
<literal>triple-isolate
</literal> option for
5000 <command>tc qdisc
</command> command. See also
5001 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5004 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5008 <para>Defaults to unset and the kernel's default is used.
</para>
5010 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5015 <term><varname>NAT=
</varname></term>
5017 <para>Takes a boolean value. When true, CAKE performs a NAT lookup before applying
5018 flow-isolation rules, to determine the true addresses and port numbers of the packet, to
5019 improve fairness between hosts inside the NAT. This has no practical effect when
5020 <varname>FlowIsolationMode=
</varname> is
<literal>none
</literal> or
<literal>flows
</literal>,
5021 or if NAT is performed on a different host. Defaults to unset, and the kernel's default is
5024 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5029 <term><varname>PriorityQueueingPreset=
</varname></term>
5031 <para>CAKE divides traffic into
<literal>tins
</literal>, and each tin has its own independent
5032 set of flow-isolation queues, bandwidth threshold, and priority. This specifies the preset of
5033 tin profiles. The available values are:
</para>
5037 <term><option>besteffort
</option></term>
5039 Disables priority queueing by placing all traffic in one tin.
5042 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5045 <term><option>precedence
</option></term>
5047 Enables priority queueing based on the legacy interpretation of TOS
5048 <literal>Precedence
</literal> field. Use of this preset on the modern Internet is
5052 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5055 <term><option>diffserv8
</option></term>
5057 Enables priority queueing based on the Differentiated Service
5058 (
<literal>DiffServ
</literal>) field with eight tins: Background Traffic, High
5059 Throughput, Best Effort, Video Streaming, Low Latency Transactions, Interactive Shell,
5060 Minimum Latency, and Network Control.
5063 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5066 <term><option>diffserv4
</option></term>
5068 Enables priority queueing based on the Differentiated Service
5069 (
<literal>DiffServ
</literal>) field with four tins: Background Traffic, Best Effort,
5070 Streaming Media, and Latency Sensitive.
5073 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5076 <term><option>diffserv3
</option></term>
5078 Enables priority queueing based on the Differentiated Service
5079 (
<literal>DiffServ
</literal>) field with three tins: Background Traffic, Best Effort,
5080 and Latency Sensitive.
5083 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5087 <para>Defaults to unset, and the kernel's default is used.
</para>
5089 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5094 <term><varname>FirewallMark=
</varname></term>
5096 <para>Takes an integer in the range
1…
4294967295. When specified, firewall-mark-based
5097 overriding of CAKE's tin selection is enabled. Defaults to unset, and the kernel's default is
5100 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5105 <term><varname>Wash=
</varname></term>
5107 <para>Takes a boolean value. When true, CAKE clears the DSCP fields, except for ECN bits, of
5108 any packet passing through CAKE. Defaults to unset, and the kernel's default is used.
</para>
5110 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5115 <term><varname>SplitGSO=
</varname></term>
5117 <para>Takes a boolean value. When true, CAKE will split General Segmentation Offload (GSO)
5118 super-packets into their on-the-wire components and dequeue them individually. Defaults to
5119 unset, and the kernel's default is used.
</para>
5121 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5126 <term><varname>RTTSec=
</varname></term>
5128 <para>Specifies the RTT for the filter. Takes a timespan. Typical values are e.g.
100us for
5129 extremely high-performance
10GigE+ networks like datacentre,
1ms for non-WiFi LAN connections,
5130 100ms for typical internet connections. Defaults to unset, and the kernel's default will be used.
5133 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
5138 <term><varname>AckFilter=
</varname></term>
5140 <para>Takes a boolean value, or special value
<literal>aggressive
</literal>. If enabled, ACKs in
5141 each flow are queued and redundant ACKs to the upstream are dropped. If yes, the filter will always
5142 keep at least two redundant ACKs in the queue, while in
<literal>aggressive
</literal> mode, it will
5143 filter down to a single ACK. This may improve download throughput on links with very asymmetrical
5144 rate limits. Defaults to unset, and the kernel's default will be used.
</para>
5146 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
5154 <title>[ControlledDelay] Section Options
</title>
5155 <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
5156 controlled delay (CoDel).
</para>
5158 <variablelist class='network-directives'
>
5159 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5160 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5163 <term><varname>PacketLimit=
</varname></term>
5165 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
5166 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
5167 kernel's default is used.
</para>
5169 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5174 <term><varname>TargetSec=
</varname></term>
5176 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
5177 Defaults to unset and kernel's default is used.
</para>
5179 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5184 <term><varname>IntervalSec=
</varname></term>
5186 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
5187 become too stale. Defaults to unset and kernel's default is used.
</para>
5189 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5194 <term><varname>ECN=
</varname></term>
5196 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
5197 unset and kernel's default is used.
</para>
5199 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5204 <term><varname>CEThresholdSec=
</varname></term>
5206 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5207 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5209 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5216 <title>[DeficitRoundRobinScheduler] Section Options
</title>
5217 <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
5218 Robin Scheduler (DRR).
</para>
5220 <variablelist class='network-directives'
>
5221 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5222 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5227 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
5228 <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
5229 Robin Scheduler (DRR).
</para>
5231 <variablelist class='network-directives'
>
5232 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5233 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5236 <term><varname>QuantumBytes=
</varname></term>
5238 <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
5239 to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5240 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to the MTU of the
5243 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5251 <title>[EnhancedTransmissionSelection] Section Options
</title>
5252 <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
5253 Transmission Selection (ETS).
</para>
5255 <variablelist class='network-directives'
>
5256 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5257 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5260 <term><varname>Bands=
</varname></term>
5262 <para>Specifies the number of bands. An unsigned integer in the range
1…
16. This value has to be at
5263 least large enough to cover the strict bands specified through the
<varname>StrictBands=
</varname>
5264 and bandwidth-sharing bands specified in
<varname>QuantumBytes=
</varname>.
</para>
5266 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5271 <term><varname>StrictBands=
</varname></term>
5273 <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
5274 the range
1…
16.
</para>
5276 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5281 <term><varname>QuantumBytes=
</varname></term>
5283 <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
5284 suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5285 respectively, to the base of
1024. This setting can be specified multiple times. If an empty
5286 string is assigned, then the all previous assignments are cleared.
</para>
5288 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5293 <term><varname>PriorityMap=
</varname></term>
5295 <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
5296 separated list of numbers. The first number indicates which band the packets with priority
0 should
5297 be put to, the second is for priority
1, and so on. There can be up to
16 numbers in the list. If
5298 there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
5299 the last one. Each band number must be in the range
0…
255. This setting can be specified multiple
5300 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
5302 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5309 <title>[GenericRandomEarlyDetection] Section Options
</title>
5310 <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
5311 Early Detection (GRED).
</para>
5313 <variablelist class='network-directives'
>
5314 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5315 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5318 <term><varname>VirtualQueues=
</varname></term>
5320 <para>Specifies the number of virtual queues. Takes an integer in the range
1…
16. Defaults to unset
5321 and kernel's default is used.
</para>
5323 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5328 <term><varname>DefaultVirtualQueue=
</varname></term>
5330 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
5331 Defaults to unset and kernel's default is used.
</para>
5333 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5338 <term><varname>GenericRIO=
</varname></term>
5340 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
5341 unset and kernel's default is used.
</para>
5343 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5350 <title>[FairQueueingControlledDelay] Section Options
</title>
5351 <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
5352 controlled delay (FQ-CoDel).
</para>
5354 <variablelist class='network-directives'
>
5355 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5356 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5359 <term><varname>PacketLimit=
</varname></term>
5361 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
5362 dropped. Defaults to unset and kernel's default is used.
</para>
5364 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5369 <term><varname>MemoryLimitBytes=
</varname></term>
5371 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
5372 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5373 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
5375 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5380 <term><varname>Flows=
</varname></term>
5382 <para>Specifies the number of flows into which the incoming packets are classified.
5383 Defaults to unset and kernel's default is used.
</para>
5385 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5390 <term><varname>TargetSec=
</varname></term>
5392 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
5393 Defaults to unset and kernel's default is used.
</para>
5395 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5400 <term><varname>IntervalSec=
</varname></term>
5402 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
5403 become too stale. Defaults to unset and kernel's default is used.
</para>
5405 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5410 <term><varname>QuantumBytes=
</varname></term>
5412 <para>Specifies the number of bytes used as the
"deficit" in the fair queuing algorithm timespan.
5413 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5414 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
5416 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5421 <term><varname>ECN=
</varname></term>
5423 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
5424 unset and kernel's default is used.
</para>
5426 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5431 <term><varname>CEThresholdSec=
</varname></term>
5433 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5434 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5436 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5443 <title>[FairQueueing] Section Options
</title>
5444 <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
5447 <variablelist class='network-directives'
>
5448 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5449 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5452 <term><varname>PacketLimit=
</varname></term>
5454 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
5455 dropped. Defaults to unset and kernel's default is used.
</para>
5457 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5462 <term><varname>FlowLimit=
</varname></term>
5464 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
5465 unset and kernel's default is used.
</para>
5467 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5472 <term><varname>QuantumBytes=
</varname></term>
5474 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
5475 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5476 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
5477 default is used.
</para>
5479 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5484 <term><varname>InitialQuantumBytes=
</varname></term>
5486 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
5487 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
5488 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
5489 kernel's default is used.
</para>
5491 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5496 <term><varname>MaximumRate=
</varname></term>
5498 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
5499 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
5500 1000. Defaults to unset and kernel's default is used.
</para>
5502 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5507 <term><varname>Buckets=
</varname></term>
5509 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
5510 kernel's default is used.
</para>
5512 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5517 <term><varname>OrphanMask=
</varname></term>
5519 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
5520 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
5521 kernel's default is used.
</para>
5523 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5528 <term><varname>Pacing=
</varname></term>
5530 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
5531 default is used.
</para>
5533 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5538 <term><varname>CEThresholdSec=
</varname></term>
5540 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5541 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5543 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5550 <title>[TrivialLinkEqualizer] Section Options
</title>
5551 <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
5552 equalizer (teql).
</para>
5554 <variablelist class='network-directives'
>
5555 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5556 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5559 <term><varname>Id=
</varname></term>
5561 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
5562 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
5563 <constant>max_equalizers=N+
1</constant> option must be loaded before
5564 <command>systemd-networkd
</command> is started.
</para>
5566 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5573 <title>[HierarchyTokenBucket] Section Options
</title>
5574 <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
5575 bucket (htb).
</para>
5577 <variablelist class='network-directives'
>
5578 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5579 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5582 <term><varname>DefaultClass=
</varname></term>
5584 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
5585 to the class. Defaults to unset.
</para>
5587 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5592 <term><varname>RateToQuantum=
</varname></term>
5594 <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
5595 configured in
<varname>Rate=
</varname> by
<varname>RateToQuantum=
</varname>.
</para>
5597 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5604 <title>[HierarchyTokenBucketClass] Section Options
</title>
5605 <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
5608 <variablelist class='network-directives'
>
5609 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5610 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5613 <term><varname>Priority=
</varname></term>
5615 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
5616 priority field are tried for packets first.
</para>
5618 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5623 <term><varname>QuantumBytes=
</varname></term>
5625 <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
5626 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
5629 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5634 <term><varname>MTUBytes=
</varname></term>
5636 <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
5637 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
5639 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5644 <term><varname>OverheadBytes=
</varname></term>
5646 <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
5647 computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5648 Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
5650 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5655 <term><varname>Rate=
</varname></term>
5657 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
5658 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
5659 to the base of
1000. This setting is mandatory.
</para>
5661 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5666 <term><varname>CeilRate=
</varname></term>
5668 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
5669 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
5670 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
5673 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5678 <term><varname>BufferBytes=
</varname></term>
5680 <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
5681 with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
5682 to the base of
1024.
</para>
5684 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5689 <term><varname>CeilBufferBytes=
</varname></term>
5691 <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
5692 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5693 respectively, to the base of
1024.
</para>
5695 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5702 <title>[HeavyHitterFilter] Section Options
</title>
5703 <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
5706 <variablelist class='network-directives'
>
5707 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5708 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5711 <term><varname>PacketLimit=
</varname></term>
5713 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
5714 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
5715 kernel's default is used.
</para>
5717 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5724 <title>[QuickFairQueueing] Section Options
</title>
5725 <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
5728 <variablelist class='network-directives'
>
5729 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5730 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5735 <title>[QuickFairQueueingClass] Section Options
</title>
5736 <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
5739 <variablelist class='network-directives'
>
5740 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5741 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5744 <term><varname>Weight=
</varname></term>
5746 <para>Specifies the weight of the class. Takes an integer in the range
1…
1023. Defaults to
5747 unset in which case the kernel default is used.
</para>
5749 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5754 <term><varname>MaxPacketBytes=
</varname></term>
5756 <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the
5757 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
5758 1024. When unset, the kernel default is used.
</para>
5760 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5767 <title>[BridgeVLAN] Section Options
</title>
5768 <para>The [BridgeVLAN] section manages the VLAN ID configuration of a bridge port and accepts the
5769 following keys. Specify several [BridgeVLAN] sections to configure several VLAN entries. The
5770 <varname>VLANFiltering=
</varname> option has to be enabled, see the [Bridge] section in
5771 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
5773 <variablelist class='network-directives'
>
5775 <term><varname>VLAN=
</varname></term>
5777 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. Takes
5778 an integer in the range
1…
4094.
</para>
5780 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5784 <term><varname>EgressUntagged=
</varname></term>
5786 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
5787 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
5788 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
5790 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5794 <term><varname>PVID=
</varname></term>
5796 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
5797 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
5798 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
5800 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5807 <title>Examples
</title>
5809 <title>Static network configuration
</title>
5811 <programlisting># /etc/systemd/network/
50-static.network
5816 Address=
192.168.0.15/
24
5817 Gateway=
192.168.0.1</programlisting>
5819 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
5820 specified gateway will be used for a default route.
</para>
5824 <title>DHCP on ethernet links
</title>
5826 <programlisting># /etc/systemd/network/
80-dhcp.network
5831 DHCP=yes
</programlisting>
5833 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
5834 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
5838 <title>IPv6 Prefix Delegation (DHCPv6 PD)
</title>
5840 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-upstream.network
5847 # The below setting is optional, to also assign an address in the delegated prefix
5848 # to the upstream interface. If not necessary, then comment out the line below and
5849 # the [DHCPPrefixDelegation] section.
5850 DHCPPrefixDelegation=yes
5852 # If the upstream network provides Router Advertisement with Managed bit set,
5853 # then comment out the line below and WithoutRA= setting in the [DHCPv6] section.
5859 [DHCPPrefixDelegation]
5860 UplinkInterface=:self
5862 Announce=no
</programlisting>
5864 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-downstream.network
5869 DHCPPrefixDelegation=yes
5872 # It is expected that the host is acting as a router. So, usually it is not
5873 # necessary to receive Router Advertisement from other hosts in the downstream network.
5876 [DHCPPrefixDelegation]
5877 UplinkInterface=enp1s0
5879 Announce=yes
</programlisting>
5881 <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
5882 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
5883 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
5888 <title>IPv6 Prefix Delegation (DHCPv4
6RD)
</title>
5890 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-upstream.network
5897 # When DHCPv4-
6RD is used, the upstream network does not support IPv6.
5898 # Hence, it is not necessary to wait for Router Advertisement, which is enabled by default.
5902 Use6RD=yes
</programlisting>
5904 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-downstream.network
5909 DHCPPrefixDelegation=yes
5912 # It is expected that the host is acting as a router. So, usually it is not
5913 # necessary to receive Router Advertisement from other hosts in the downstream network.
5916 [DHCPPrefixDelegation]
5917 UplinkInterface=enp1s0
5919 Announce=yes
</programlisting>
5921 <para>This will enable DHCPv4-
6RD on the interface enp1s0 as an upstream interface where the
5922 DHCPv4 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
5923 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
5928 <title>A bridge with two enslaved links
</title>
5930 <programlisting># /etc/systemd/network/
25-bridge-static.netdev
5933 Kind=bridge
</programlisting>
5935 <programlisting># /etc/systemd/network/
25-bridge-static.network
5940 Address=
192.168.0.15/
24
5942 DNS=
192.168.0.1</programlisting>
5944 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
5949 Bridge=bridge0
</programlisting>
5951 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
5956 Bridge=bridge0
</programlisting>
5958 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
5959 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
5960 and network assigned, and a default route via the specified gateway will be
5961 added. The specified DNS server will be added to the global list of DNS resolvers.
5966 <title>Bridge port with VLAN forwarding
</title>
5969 # /etc/systemd/network/
25-bridge-slave-interface-
1.network
5985 EgressUntagged=
300-
400</programlisting>
5987 <para>This overrides the configuration specified in the previous example for the
5988 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
5989 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
5990 untagged when they leave on this interface. Untagged packets which arrive on this
5991 interface will be assigned VLAN ID
42.
</para>
5995 <title>Various tunnels
</title>
5997 <programlisting>/etc/systemd/network/
25-tunnels.network
6008 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
6014 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
6020 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
6026 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
6032 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
6033 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
6037 <title>A bond device
</title>
6039 <programlisting># /etc/systemd/network/
30-bond1.network
6047 <programlisting># /etc/systemd/network/
30-bond1.netdev
6053 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
6055 MACAddress=
52:
54:
00:e9:
64:
41
6061 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
6063 MACAddress=
52:
54:
00:e9:
64:
42
6069 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
6070 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
6071 will be used to acquire an address.
</para>
6075 <title>Virtual Routing and Forwarding (VRF)
</title>
6076 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
6077 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
6078 within the routing table defined during VRF creation. For kernels before
4.8 traffic
6079 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
6081 <programlisting># /etc/systemd/network/
25-vrf.network
6091 <title>MacVTap
</title>
6092 <para>This brings up a network interface
<literal>macvtap-test
</literal>
6093 and attaches it to
<literal>enp0s25
</literal>.
</para>
6094 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
6099 MACVTAP=macvtap-test
6104 <title>A Xfrm interface with physical underlying device.
</title>
6106 <programlisting># /etc/systemd/network/
27-xfrm.netdev
6112 InterfaceId=
7</programlisting>
6114 <programlisting># /etc/systemd/network/
27-eth0.network
6119 Xfrm=xfrm0
</programlisting>
6121 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
6122 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
6123 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
6129 <title>See Also
</title>
6131 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
6132 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
6133 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
6134 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
6135 <citerefentry><refentrytitle>systemd-network-generator.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
6136 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>