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 smaller than
<literal>70</literal> (e.g.
<filename>10-eth0.network
</filename>). Otherwise, the
48 default
<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>Note that any network interfaces that have the
<varname>ID_NET_MANAGED_BY=
</varname> udev property
81 set will never be matched by any .network files – unless the property's value is the string
82 <literal>io.systemd.Network
</literal> – even if the [Match] section would otherwise match. This may be
83 used to exclude specific network interfaces from
<command>systemd-networkd
</command>'s management, while
84 keeping the [Match] section generic. The
<varname>ID_NET_MANAGED_BY=
</varname> property thus declares
85 intended
<emphasis>ownership
</emphasis> of the device, and permits ensuring that concurrent network
86 management implementations do not compete for management of specific devices.
</para>
88 <para>A network file is said to match a network interface if all matches specified by the [Match]
89 section are satisfied. When a network file does not contain valid settings in [Match] section, then
90 the file will match all interfaces and
<command>systemd-networkd
</command> warns about that. Hint:
91 to avoid the warning and to make it clear that all interfaces shall be matched, add the following:
92 <programlisting>Name=*
</programlisting> The following keys are accepted:
</para>
94 <variablelist class='network-directives'
>
95 <xi:include href=
"systemd.link.xml" xpointer=
"mac-address" />
96 <xi:include href=
"systemd.link.xml" xpointer=
"permanent-mac-address" />
97 <xi:include href=
"systemd.link.xml" xpointer=
"path" />
98 <xi:include href=
"systemd.link.xml" xpointer=
"driver" />
99 <xi:include href=
"systemd.link.xml" xpointer=
"type" />
100 <xi:include href=
"systemd.link.xml" xpointer=
"kind" />
101 <xi:include href=
"systemd.link.xml" xpointer=
"property" />
104 <term><varname>Name=
</varname></term>
106 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
107 by the udev property
<literal>INTERFACE
</literal>, or device's alternative names. If the
108 list is prefixed with a
"!", the test is inverted.
</para>
110 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
115 <term><varname>WLANInterfaceType=
</varname></term>
117 <para>A whitespace-separated list of wireless network type. Supported values are
118 <literal>ad-hoc
</literal>,
<literal>station
</literal>,
<literal>ap
</literal>,
119 <literal>ap-vlan
</literal>,
<literal>wds
</literal>,
<literal>monitor
</literal>,
120 <literal>mesh-point
</literal>,
<literal>p2p-client
</literal>,
<literal>p2p-go
</literal>,
121 <literal>p2p-device
</literal>,
<literal>ocb
</literal>, and
<literal>nan
</literal>. If the
122 list is prefixed with a
"!", the test is inverted.
</para>
124 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
129 <term><varname>SSID=
</varname></term>
131 <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
132 connected wireless LAN. If the list is prefixed with a
"!", the test is inverted.
</para>
134 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
139 <term><varname>BSSID=
</varname></term>
141 <para>A whitespace-separated list of hardware address of the currently connected wireless
142 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
143 <varname>MACAddress=
</varname>. This option may appear more than once, in which case the
144 lists are merged. If the empty string is assigned to this option, the list is reset.
</para>
146 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
150 <xi:include href=
"systemd.link.xml" xpointer=
"host" />
151 <xi:include href=
"systemd.link.xml" xpointer=
"virtualization" />
152 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-command-line" />
153 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-version" />
154 <xi:include href=
"systemd.link.xml" xpointer=
"credential" />
155 <xi:include href=
"systemd.link.xml" xpointer=
"architecture" />
156 <xi:include href=
"systemd.link.xml" xpointer=
"firmware" />
161 <title>[Link] Section Options
</title>
163 <para>The [Link] section accepts the following keys:
</para>
165 <variablelist class='network-directives'
>
167 <term><varname>MACAddress=
</varname></term>
169 <para>The hardware address to set for the device.
</para>
171 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
176 <term><varname>MTUBytes=
</varname></term>
178 <para>The maximum transmission unit in bytes to set for the device. The usual suffixes K, M,
179 G, are supported and are understood to the base of
1024.
</para>
180 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen below
1280 (the
181 minimum MTU for IPv6) it will automatically be increased to this value.
</para>
183 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
188 <term><varname>ARP=
</varname></term>
190 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
191 for this interface is enabled. When unset, the kernel's default will be used.
</para>
192 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
193 interfaces atop a single lower-level physical interface, which will then only serve as a
194 link/
"bridge" device aggregating traffic to the same physical link and not participate in
195 the network otherwise. Defaults to unset.
</para>
197 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
202 <term><varname>Multicast=
</varname></term>
204 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults
207 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
212 <term><varname>AllMulticast=
</varname></term>
214 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the
215 network. This happens when multicast routing is enabled. Defaults to unset.
</para>
217 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
222 <term><varname>Promiscuous=
</varname></term>
224 <para>Takes a boolean. If set to true, promiscuous mode of the interface is enabled. Defaults
226 <para>If this is set to false for the underlying link of a
<literal>passthru
</literal> mode
227 MACVLAN/MACVTAP, the virtual interface will be created with the
<literal>nopromisc
</literal>
230 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
235 <term><varname>Unmanaged=
</varname></term>
237 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are made to bring up or
238 configure matching links, equivalent to when there are no matching network files. Defaults to
239 <literal>no
</literal>.
</para>
240 <para>This is useful for preventing later matching network files from interfering with
241 certain interfaces that are fully controlled by other applications.
</para>
243 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
248 <term><varname>Group=
</varname></term>
250 <para>Link groups are similar to port ranges found in managed switches. When network
251 interfaces are added to a numbered group, operations on all the interfaces from that group
252 can be performed at once. Takes an unsigned integer in the range
0…
2147483647. Defaults to
255 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
260 <term><varname>RequiredForOnline=
</varname></term>
262 <para>Takes a boolean or a minimum operational state and an optional maximum operational
264 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
265 for possible operational states. When
<literal>yes
</literal>, the network is deemed required
266 when determining whether the system is online (including when running
267 <command>systemd-networkd-wait-online
</command>). When
<literal>no
</literal>, the network is
268 ignored when determining the online state. When a minimum operational state and an optional
269 maximum operational state are set,
<literal>yes
</literal> is implied, and this controls the
270 minimum and maximum operational state required for the network interface to be considered
273 <para>Defaults to
<literal>yes
</literal> when
<varname>ActivationPolicy=
</varname> is not
274 set, or set to
<literal>up
</literal>,
<literal>always-up
</literal>, or
275 <literal>bound
</literal>. Defaults to
<literal>no
</literal> when
276 <varname>ActivationPolicy=
</varname> is set to
<literal>manual
</literal> or
277 <literal>down
</literal>. This is forced to
<literal>no
</literal> when
278 <varname>ActivationPolicy=
</varname> is set to
<literal>always-down
</literal>.
</para>
280 <para>The network will be brought up normally (as configured by
281 <varname>ActivationPolicy=
</varname>), but in the event that there is no address being
282 assigned by DHCP or the cable is not plugged in, the link will simply remain offline and be
283 skipped automatically by
<command>systemd-networkd-wait-online
</command> if
284 <literal>RequiredForOnline=no
</literal>.
</para>
286 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
291 <term><varname>RequiredFamilyForOnline=
</varname></term>
293 <para>Takes an address family. When specified, an IP address in the given family is deemed
294 required when determining whether the link is online (including when running
295 <command>systemd-networkd-wait-online
</command>). Takes one of
<literal>ipv4
</literal>,
296 <literal>ipv6
</literal>,
<literal>both
</literal>, or
<literal>any
</literal>. Defaults to
297 <literal>any
</literal>. Note that this option has no effect if
298 <literal>RequiredForOnline=no
</literal>, or if
<literal>RequiredForOnline=
</literal>
299 specifies a minimum operational state below
<literal>degraded
</literal>.
</para>
301 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
306 <term><varname>ActivationPolicy=
</varname></term>
308 <para>Specifies the policy for
<command>systemd-networkd
</command> managing the link
309 administrative state. Specifically, this controls how
<command>systemd-networkd
</command>
310 changes the network device's
<literal>IFF_UP
</literal> flag, which is sometimes
311 controlled by system administrators by running e.g.,
312 <command>ip link set dev eth0 up
</command> or
<command>ip link set dev eth0 down
</command>,
313 and can also be changed with
<command>networkctl up eth0
</command> or
314 <command>networkctl down eth0
</command>.
</para>
316 <para>Takes one of
<literal>up
</literal>,
<literal>always-up
</literal>,
317 <literal>manual
</literal>,
<literal>always-down
</literal>,
<literal>down
</literal>,
318 or
<literal>bound
</literal>. When
<literal>manual
</literal>,
319 <command>systemd-networkd
</command> will not change the link's admin state automatically;
320 the system administrator must bring the interface up or down manually, as desired. When
321 <literal>up
</literal> (the default) or
<literal>always-up
</literal>, or
322 <literal>down
</literal> or
<literal>always-down
</literal>,
323 <command>systemd-networkd
</command> will set the link up or down, respectively, when the
324 interface is (re)configured. When
<literal>always-up
</literal> or
325 <literal>always-down
</literal>,
<command>systemd-networkd
</command> will set the link up or
326 down, respectively, any time
<command>systemd-networkd
</command> detects a change in the
327 administrative state. When
<varname>BindCarrier=
</varname> is also set, this is automatically
328 set to
<literal>bound
</literal> and any other value is ignored.
</para>
330 <para>When the policy is set to
<literal>down
</literal> or
<literal>manual
</literal>, the
331 default value of
<varname>RequiredForOnline=
</varname> is
<literal>no
</literal>. When the
332 policy is set to
<literal>always-down
</literal>, the value of
333 <varname>RequiredForOnline=
</varname> forced to
<literal>no
</literal>.
</para>
335 <para>The administrative state is not the same as the carrier state, so using
336 <literal>always-up
</literal> does not mean the link will never lose carrier. The link carrier
337 depends on both the administrative state as well as the network device's physical connection.
338 However, to avoid reconfiguration failures, when using
<literal>always-up
</literal>,
339 <varname>IgnoreCarrierLoss=
</varname> is forced to true.
</para>
341 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
347 <xi:include href=
"systemd.link.xml" xpointer=
"sr-iov" />
350 <title>[Network] Section Options
</title>
352 <para>The [Network] section accepts the following keys:
</para>
354 <variablelist class='network-directives'
>
356 <term><varname>Description=
</varname></term>
358 <para>A description of the device. This is only used for presentation purposes.
</para>
360 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
365 <term><varname>DHCP=
</varname></term>
367 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
<literal>yes
</literal>,
368 <literal>no
</literal>,
<literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults to
369 <literal>no
</literal>.
</para>
371 <para>Note that DHCPv6 will by default be triggered by Router Advertisements, if reception is
372 enabled, regardless of this parameter. By explicitly enabling DHCPv6 support here, the DHCPv6
373 client will be started in the mode specified by the
<varname>WithoutRA=
</varname> setting in the
374 [DHCPv6] section, regardless of the presence of routers on the link, or what flags the routers
375 pass. See
<varname>IPv6AcceptRA=
</varname>.
</para>
377 <para>Furthermore, note that by default the domain name specified through DHCP is not used
378 for name resolution. See option
<option>UseDomains=
</option> below.
</para>
380 <para>See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the
381 DHCP client support.
</para>
383 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
388 <term><varname>DHCPServer=
</varname></term>
390 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started.
391 Defaults to
<literal>no
</literal>. Further settings for the DHCP server may be set in the
392 [DHCPServer] section described below.
</para>
394 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
399 <term><varname>LinkLocalAddressing=
</varname></term>
401 <para>Enables link-local address autoconfiguration. Accepts
<option>yes
</option>,
402 <option>no
</option>,
<option>ipv4
</option>, and
<option>ipv6
</option>. An IPv6 link-local
403 address is configured when
<option>yes
</option> or
<option>ipv6
</option>. An IPv4 link-local
404 address is configured when
<option>yes
</option> or
<option>ipv4
</option> and when DHCPv4
405 autoconfiguration has been unsuccessful for some time. (IPv4 link-local address
406 autoconfiguration will usually happen in parallel with repeated attempts to acquire a DHCPv4
409 <para>Defaults to
<option>no
</option> when
<varname>KeepMaster=
</varname> or
410 <varname>Bridge=
</varname> is set or when the specified
411 <varname>MACVLAN=
</varname>/
<varname>MACVTAP=
</varname> has
<varname>Mode=passthru
</varname>,
412 or
<option>ipv6
</option> otherwise.
</para>
414 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
419 <term><varname>IPv6LinkLocalAddressGenerationMode=
</varname></term>
421 <para>Specifies how IPv6 link-local address is generated. Takes one of
422 <literal>eui64
</literal>,
<literal>none
</literal>,
<literal>stable-privacy
</literal> and
423 <literal>random
</literal>. When unset,
<literal>stable-privacy
</literal> is used if
424 <varname>IPv6StableSecretAddress=
</varname> is specified, and if not,
425 <literal>eui64
</literal> is used. Note that if
<varname>LinkLocalAddressing=
</varname> is
426 <literal>no
</literal> or
<literal>ipv4
</literal>, then
427 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> will be ignored. Also, even if
428 <varname>LinkLocalAddressing=
</varname> is
<literal>yes
</literal> or
<literal>ipv6
</literal>,
429 setting
<varname>IPv6LinkLocalAddressGenerationMode=none
</varname>
430 disables to configure an IPv6 link-local address.
</para>
432 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
437 <term><varname>IPv6StableSecretAddress=
</varname></term>
439 <para>Takes an IPv6 address. The specified address will be used as a stable secret for
440 generating IPv6 link-local address. If this setting is specified, and
441 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> is unset, then
442 <varname>IPv6LinkLocalAddressGenerationMode=stable-privacy
</varname> is implied.
443 If this setting is not specified, and
<literal>stable-privacy
</literal> is set to
444 <varname>IPv6LinkLocalAddressGenerationMode=
</varname>,
445 then a stable secret address will be generated from the local machine ID and the interface
448 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
453 <term><varname>IPv4LLStartAddress=
</varname></term>
455 <para>Specifies the first IPv4 link-local address to try. Takes an IPv4 address for example
456 169.254.1.2, from the link-local address range:
169.254.0.0/
16 except for
169.254.0.0/
24 and
457 169.254.255.0/
24. This setting may be useful if the device should always have the same address
458 as long as there is no address conflict. When unset, a random address will be automatically
459 selected. Defaults to unset.
</para>
461 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
466 <term><varname>IPv4LLRoute=
</varname></term>
468 <para>Takes a boolean. If set to true, sets up the route needed for non-IPv4LL hosts to
469 communicate with IPv4LL-only hosts. Defaults to false.
</para>
471 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
476 <term><varname>DefaultRouteOnDevice=
</varname></term>
478 <para>Takes a boolean. If set to true, sets up the IPv4 default route bound to the interface.
479 Defaults to false. This is useful when creating routes on point-to-point interfaces. This is
480 equivalent to e.g. the following,
481 <programlisting>ip route add default dev veth99
</programlisting>
483 <programlisting>[Route]
484 Gateway=
0.0.0.0</programlisting></para>
485 <para>Currently, there are no way to specify e.g., the table for the route configured by this
486 setting. To configure the default route with such an additional property, please use the
488 <programlisting>[Route]
490 Table=
1234</programlisting></para>
491 <para>If you'd like to create an IPv6 default route bound to the interface, please use the
493 <programlisting>[Route]
495 Table=
1234</programlisting></para>
497 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
502 <term><varname>LLMNR=
</varname></term>
504 <para>Takes a boolean or
<literal>resolve
</literal>. When true, enables
505 <ulink url=
"https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution
</ulink>
506 on the link. When set to
<literal>resolve
</literal>, only resolution is enabled, but not host
507 registration and announcement. Defaults to true. This setting is read by
508 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
511 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
516 <term><varname>MulticastDNS=
</varname></term>
518 <para>Takes a boolean or
<literal>resolve
</literal>. When true, enables
519 <ulink url=
"https://tools.ietf.org/html/rfc6762">Multicast DNS
</ulink> support on the link.
520 When set to
<literal>resolve
</literal>, only resolution is enabled, but not host or service
521 registration and announcement. Defaults to false. This setting is read by
522 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
525 <xi:include href=
"version-info.xml" xpointer=
"v229"/>
530 <term><varname>DNSOverTLS=
</varname></term>
532 <para>Takes a boolean or
<literal>opportunistic
</literal>. When true, enables
533 <ulink url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink> support on the link.
534 When set to
<literal>opportunistic
</literal>, compatibility with non-DNS-over-TLS servers is
535 increased, by automatically turning off DNS-over-TLS servers in this case. This option
536 defines a per-interface setting for
537 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
538 global
<varname>DNSOverTLS=
</varname> option. Defaults to unset, and the global setting will
539 be used. This setting is read by
540 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
543 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
548 <term><varname>DNSSEC=
</varname></term>
550 <para>Takes a boolean or
<literal>allow-downgrade
</literal>. When true, enables
551 <ulink url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink> DNS validation support on the
552 link. When set to
<literal>allow-downgrade
</literal>, compatibility with non-DNSSEC capable
553 networks is increased, by automatically turning off DNSSEC in this case. This option defines
554 a per-interface setting for
555 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
556 global
<varname>DNSSEC=
</varname> option. Defaults to unset, and the global setting will be
557 used. This setting is read by
558 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
561 <xi:include href=
"version-info.xml" xpointer=
"v229"/>
566 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
568 <para>A space-separated list of DNSSEC negative trust anchor domains. If specified and DNSSEC
569 is enabled, look-ups done via the interface's DNS server will be subject to the list of
570 negative trust anchors, and not require authentication for the specified domains, or anything
571 below it. Use this to disable DNSSEC authentication for specific private domains, that cannot
572 be proven valid using the Internet DNS hierarchy. Defaults to the empty list. This setting is
574 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
577 <xi:include href=
"version-info.xml" xpointer=
"v229"/>
582 <term><varname>LLDP=
</varname></term>
584 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol
585 commonly implemented on professional routers and bridges which announces which physical port
586 a system is connected to, as well as other related data. Accepts a boolean or the special
587 value
<literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a
588 database of all LLDP neighbors maintained. If
<literal>routers-only
</literal> is set only
589 LLDP data of various types of routers is collected and LLDP data about other types of devices
590 ignored (such as stations, telephones and others). If false, LLDP reception is disabled.
591 Defaults to
<literal>routers-only
</literal>. Use
592 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
593 to query the collected neighbor data. LLDP is only available on Ethernet links. See
594 <varname>EmitLLDP=
</varname> below for enabling LLDP packet emission from the local system.
597 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
602 <term><varname>EmitLLDP=
</varname></term>
604 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the
605 special values
<literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
606 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission.
607 If not false, a short LLDP packet with information about the local system is sent out in
608 regular intervals on the link. The LLDP packet will contain information about the local
609 hostname, the local machine ID (as stored in
610 <citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
611 and the local interface name, as well as the pretty hostname of the system (as set in
612 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
613 LLDP emission is only available on Ethernet links. Note that this setting passes data
614 suitable for identification of host to the network and should thus not be enabled on
615 untrusted networks, where such identification data should not be made available. Use this
616 option to permit other systems to identify on which interfaces they are connected to this
617 system. The three special values control propagation of the LLDP packets. The
618 <literal>nearest-bridge
</literal> setting permits propagation only to the nearest connected
619 bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays,
620 but not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until
621 a customer bridge is reached. For details about these concepts, see
622 <ulink url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>.
623 Note that configuring this setting to true is equivalent to
624 <literal>nearest-bridge
</literal>, the recommended and most restricted level of propagation.
625 See
<varname>LLDP=
</varname> above for an option to enable LLDP reception.
</para>
627 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
632 <term><varname>BindCarrier=
</varname></term>
634 <para>A link name or a list of link names. When set, controls the behavior of the current
635 link. When all links in the list are in an operational down state, the current link is
636 brought down. When at least one link has carrier, the current interface is brought up.
</para>
638 <para>This forces
<varname>ActivationPolicy=
</varname> to be set to
<literal>bound
</literal>.
641 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
646 <term><varname>Address=
</varname></term>
648 <para>A static IPv4 or IPv6 address and its prefix length, separated by a
649 <literal>/
</literal> character. Specify this key more than once to configure several
650 addresses. The format of the address must be as described in
651 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
652 This is a short-hand for an [Address] section only containing an Address key (see below).
653 This option may be specified more than once.
</para>
655 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
656 <literal>::
</literal> (for IPv6), a new address range of the requested size is automatically
657 allocated from a system-wide pool of unused ranges. Note that the prefix length must be equal
658 or larger than
8 for IPv4, and
64 for IPv6. The allocated range is checked against all
659 current network interfaces and all known network configuration files to avoid address range
660 conflicts. The default system-wide pool consists of
192.168.0.0/
16,
172.16.0.0/
12 and
661 10.0.0.0/
8 for IPv4, and fd00::/
8 for IPv6. This functionality is useful to manage a large
662 number of dynamically created network interfaces with the same network configuration and
663 automatic address range assignment.
</para>
665 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
670 <term><varname>Gateway=
</varname></term>
672 <para>The gateway address, which must be in the format described in
673 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
674 This is a short-hand for a [Route] section only containing a
<varname>Gateway=
</varname> key.
675 This option may be specified more than once.
</para>
677 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
682 <term><varname>DNS=
</varname></term>
684 <para>A DNS server address, which must be in the format described in
685 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
686 This option may be specified more than once. Each address can optionally take a port number
687 separated with
<literal>:
</literal>, a network interface name or index separated with
688 <literal>%
</literal>, and a Server Name Indication (SNI) separated with
<literal>#
</literal>.
689 When IPv6 address is specified with a port number, then the address must be in the square
690 brackets. That is, the acceptable full formats are
691 <literal>111.222.333.444:
9953%ifname#example.com
</literal> for IPv4 and
692 <literal>[
1111:
2222::
3333]:
9953%ifname#example.com
</literal> for IPv6. If an empty string is
693 assigned, then the all previous assignments are cleared. This setting is read by
694 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
697 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
702 <term><varname>Domains=
</varname></term>
704 <para>A whitespace-separated list of domains which should be resolved using the DNS servers
705 on this link. Each item in the list should be a domain name, optionally prefixed with a tilde
706 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
707 domains without the prefix are called
"search domains" and are first used as search suffixes
708 for extending single-label hostnames (hostnames containing no dots) to become fully qualified
709 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
710 specified search domains are appended to it in turn, converting it into a fully qualified
711 domain name, until one of them may be successfully resolved.
</para>
713 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups
714 for hostnames ending in those domains (hence also single label names, if any
"search domains"
715 are listed), are routed to the DNS servers configured for this interface. The domain routing
716 logic is particularly useful on multi-homed hosts with DNS servers serving particular private
717 DNS zones on each interface.
</para>
719 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a
720 routing domain, the dot referring to the DNS root domain which is the implied suffix of all
721 valid DNS names) has special effect. It causes all DNS traffic which does not match another
722 configured domain routing entry to be routed to DNS servers specified for this interface.
723 This setting is useful to prefer a certain set of DNS servers if a link on which they are
724 connected is available.
</para>
726 <para>This setting is read by
727 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
728 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname>
730 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
731 Domain name routing has no equivalent in the traditional glibc API, which has no concept of
732 domain name servers limited to a specific link.
</para>
734 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
739 <term><varname>DNSDefaultRoute=
</varname></term>
741 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for
742 resolving domain names that do not match any link's configured
<varname>Domains=
</varname>
743 setting. If false, this link's configured DNS servers are never used for such domains, and
744 are exclusively used for resolving names that match at least one of the domains configured on
745 this link. If not specified defaults to an automatic mode: queries not matching any link's
746 configured domains will be routed to this link if it has no routing-only domains configured.
749 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
754 <term><varname>NTP=
</varname></term>
756 <para>An NTP server address (either an IP address, or a hostname). This option may be
757 specified more than once. This setting is read by
758 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
761 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
766 <term><varname>IPForward=
</varname></term>
768 <para>Configures IP packet forwarding for the system. If enabled, incoming packets on any
769 network interface will be forwarded to any other interfaces according to the routing table.
770 Takes a boolean, or the values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>, which only
771 enable IP packet forwarding for the specified address family. This controls the
772 <filename>net.ipv4.ip_forward
</filename> and
<filename>net.ipv6.conf.all.forwarding
</filename>
773 sysctl options of the network interface (see
774 <ulink url=
"https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl
</ulink>
775 for details about sysctl options). Defaults to
<literal>no
</literal>.
</para>
777 <para>Note: this setting controls a global kernel option, and does so one way only: if a
778 network that has this setting enabled is set up the global setting is turned on. However,
779 it is never turned off again, even after all networks with this setting enabled are shut
782 <para>To allow IP packet forwarding only between specific network interfaces use a firewall.
785 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
790 <term><varname>IPMasquerade=
</varname></term>
792 <para>Configures IP masquerading for the network interface. If enabled, packets forwarded
793 from the network interface will be appear as coming from the local host. Takes one of
794 <literal>ipv4
</literal>,
<literal>ipv6
</literal>,
<literal>both
</literal>, or
795 <literal>no
</literal>. Defaults to
<literal>no
</literal>. If enabled, this automatically sets
796 <varname>IPForward=
</varname> to one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal> or
797 <literal>yes
</literal>.
</para>
798 <para>Note. Any positive boolean values such as
<literal>yes
</literal> or
799 <literal>true
</literal> are now deprecated. Please use one of the values in the above.
</para>
801 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
806 <term><varname>IPv6PrivacyExtensions=
</varname></term>
808 <para>Configures use of stateless temporary addresses that change over time (see
809 <ulink url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
810 Privacy Extensions for Stateless Address Autoconfiguration in IPv6). Takes a boolean or the
811 special values
<literal>prefer-public
</literal> and
<literal>kernel
</literal>. When true,
812 enables the privacy extensions and prefers temporary addresses over public addresses. When
813 <literal>prefer-public
</literal>, enables the privacy extensions, but prefers public
814 addresses over temporary addresses. When false, the privacy extensions remain disabled. When
815 <literal>kernel
</literal>, the kernel's default setting will be left in place. When unspecified,
816 the value specified in the same setting in
817 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
818 which defaults to
<literal>no
</literal>, will be used.
</para>
820 <xi:include href=
"version-info.xml" xpointer=
"v222"/>
825 <term><varname>IPv6AcceptRA=
</varname></term>
827 <para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
828 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they
829 may trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or
830 if no routers are found on the link. The default is to disable RA reception for bridge
831 devices or when IP forwarding is enabled, and to enable it otherwise. Cannot be enabled on
832 devices aggregated in a bond device or when link-local addressing is disabled.
</para>
834 <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA]
835 section, see below.
</para>
838 <ulink url=
"https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl
</ulink>
839 in the kernel documentation regarding
<literal>accept_ra
</literal>, but note that systemd's
840 setting of
<constant>1</constant> (i.e. true) corresponds to kernel's setting of
841 <constant>2</constant>.
</para>
843 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
844 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
845 RA protocol is used, and the kernel's own implementation remains disabled, since
846 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
847 and these are not available from the kernel if the kernel's own implementation is used.
850 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
855 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
857 <para>Configures the amount of IPv6 Duplicate Address Detection (DAD) probes to send. When
858 unset, the kernel's default will be used.
</para>
860 <xi:include href=
"version-info.xml" xpointer=
"v228"/>
865 <term><varname>IPv6HopLimit=
</varname></term>
867 <para>Configures IPv6 Hop Limit. Takes an integer in the range
1…
255. For each router that
868 forwards the packet, the hop limit is decremented by
1. When the hop limit field reaches zero, the
869 packet is discarded. When unset, the kernel's default will be used.
</para>
871 <xi:include href=
"version-info.xml" xpointer=
"v228"/>
876 <term><varname>IPv4ReversePathFilter=
</varname></term>
878 <para>Configure IPv4 Reverse Path Filtering. If enabled, when an IPv4 packet is received, the machine will first check
879 whether the
<emphasis>source
</emphasis> of the packet would be routed through the interface it came in. If there is no
880 route to the source on that interface, the machine will drop the packet. Takes one of
881 <literal>no
</literal>,
<literal>strict
</literal>, or
<literal>loose
</literal>. When
<literal>no
</literal>,
882 no source validation will be done. When
<literal>strict
</literal>, mode each incoming packet is tested against the FIB and
883 if the incoming interface is not the best reverse path, the packet check will fail. By default failed packets are discarded.
884 When
<literal>loose
</literal>, mode each incoming packet's source address is tested against the FIB. The packet is dropped
885 only if the source address is not reachable via any interface on that router.
886 See
<ulink url=
"https://tools.ietf.org/html/rfc1027">RFC
3704</ulink>.
887 When unset, the kernel's default will be used.
</para>
889 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
894 <term><varname>IPv4AcceptLocal=
</varname></term>
896 <para>Takes a boolean. Accept packets with local source addresses. In combination with
897 suitable routing, this can be used to direct packets between two local interfaces over the
898 wire and have them accepted properly. When unset, the kernel's default will be used.
</para>
900 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
905 <term><varname>IPv4RouteLocalnet=
</varname></term>
907 <para>Takes a boolean. When true, the kernel does not consider loopback addresses as martian
908 source or destination while routing. This enables the use of
127.0.0.0/
8 for local routing
909 purposes. When unset, the kernel's default will be used.
</para>
911 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
916 <term><varname>IPv4ProxyARP=
</varname></term>
918 <para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one
919 host, usually a router, answers ARP requests intended for another machine. By
"faking" its
920 identity, the router accepts responsibility for routing packets to the
"real" destination.
921 See
<ulink url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>. When unset, the
922 kernel's default will be used.
</para>
924 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
929 <term><varname>IPv6ProxyNDP=
</varname></term>
931 <para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery Protocol)
932 is a technique for IPv6 to allow routing of addresses to a different destination when peers
933 expect them to be present on a certain physical link. In this case a router answers Neighbour
934 Advertisement messages intended for another machine by offering its own MAC address as
935 destination. Unlike proxy ARP for IPv4, it is not enabled globally, but will only send
936 Neighbour Advertisement messages for addresses in the IPv6 neighbor proxy table, which can
937 also be shown by
<command>ip -
6 neighbour show proxy
</command>. systemd-networkd will control
938 the per-interface `proxy_ndp` switch for each configured interface depending on this option.
939 When unset, the kernel's default will be used.
</para>
941 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
946 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
948 <para>An IPv6 address, for which Neighbour Advertisement messages will be proxied. This
949 option may be specified more than once. systemd-networkd will add the
950 <varname>IPv6ProxyNDPAddress=
</varname> entries to the kernel's IPv6 neighbor proxy table.
951 This setting implies
<varname>IPv6ProxyNDP=yes
</varname> but has no effect if
952 <varname>IPv6ProxyNDP=
</varname> has been set to false. When unset, the kernel's default will
955 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
960 <term><varname>IPv6SendRA=
</varname></term>
962 <para>Whether to enable or disable Router Advertisement sending on a link. Takes a boolean
963 value. When enabled, prefixes configured in [IPv6Prefix] sections and routes configured in
964 the [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA] section. If
965 <varname>DHCPPrefixDelegation=
</varname> is enabled, then the delegated prefixes are also
966 distributed. See
<varname>DCHPPrefixDelegation=
</varname> setting and the [IPv6SendRA],
967 [IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation] sections for more configuration
970 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
975 <term><varname>DHCPPrefixDelegation=
</varname></term>
977 <para>Takes a boolean value. When enabled, requests subnet prefixes on another link via the DHCPv6
978 protocol or via the
6RD option in the DHCPv4 protocol. An address within each delegated prefix will
979 be assigned, and the prefixes will be announced through IPv6 Router Advertisement if
980 <varname>IPv6SendRA=
</varname> is enabled. This behaviour can be configured in the
981 [DHCPPrefixDelegation] section. Defaults to disabled.
</para>
983 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
988 <term><varname>IPv6MTUBytes=
</varname></term>
990 <para>Configures IPv6 maximum transmission unit (MTU). An integer greater than or equal to
991 1280 bytes. When unset, the kernel's default will be used.
</para>
993 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
998 <term><varname>KeepMaster=
</varname></term>
1000 <para>Takes a boolean value. When enabled, the current master interface index will not be
1001 changed, and
<varname>BatmanAdvanced=
</varname>,
<varname>Bond=
</varname>,
1002 <varname>Bridge=
</varname>, and
<varname>VRF=
</varname> settings are ignored. This may be
1003 useful when a netdev with a master interface is created by another program, e.g.
1004 <citerefentry><refentrytitle>systemd-nspawn
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
1005 Defaults to false.
</para>
1007 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
1012 <term><varname>BatmanAdvanced=
</varname></term>
1013 <term><varname>Bond=
</varname></term>
1014 <term><varname>Bridge=
</varname></term>
1015 <term><varname>VRF=
</varname></term>
1017 <para>The name of the B.A.T.M.A.N. Advanced, bond, bridge, or VRF interface to add the link
1019 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1022 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1027 <term><varname>IPoIB=
</varname></term>
1028 <term><varname>IPVLAN=
</varname></term>
1029 <term><varname>IPVTAP=
</varname></term>
1030 <term><varname>MACsec=
</varname></term>
1031 <term><varname>MACVLAN=
</varname></term>
1032 <term><varname>MACVTAP=
</varname></term>
1033 <term><varname>Tunnel=
</varname></term>
1034 <term><varname>VLAN=
</varname></term>
1035 <term><varname>VXLAN=
</varname></term>
1036 <term><varname>Xfrm=
</varname></term>
1038 <para>The name of an IPoIB, IPVLAN, IPVTAP, MACsec, MACVLAN, MACVTAP, tunnel, VLAN,
1039 VXLAN, or Xfrm to be created on the link. See
1040 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1041 This option may be specified more than once.
</para>
1043 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1048 <term><varname>ActiveSlave=
</varname></term>
1050 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
1051 option is only valid for following modes:
<literal>active-backup
</literal>,
1052 <literal>balance-alb
</literal>, and
<literal>balance-tlb
</literal>. Defaults to false.
</para>
1054 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1059 <term><varname>PrimarySlave=
</varname></term>
1061 <para>Takes a boolean. Specifies which slave is the primary device. The specified device will
1062 always be the active slave while it is available. Only when the primary is off-line will
1063 alternate devices be used. This is useful when one slave is preferred over another, e.g.
1064 when one slave has higher throughput than another. The
<literal>PrimarySlave=
</literal>
1065 option is only valid for following modes:
<literal>active-backup
</literal>,
1066 <literal>balance-alb
</literal>, and
<literal>balance-tlb
</literal>. Defaults to false.
</para>
1068 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1073 <term><varname>ConfigureWithoutCarrier=
</varname></term>
1075 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no
1076 carrier. Defaults to false. If enabled, and the
<varname>IgnoreCarrierLoss=
</varname> setting
1077 is not explicitly set, then it is enabled as well.
</para>
1079 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1084 <term><varname>IgnoreCarrierLoss=
</varname></term>
1086 <para>Takes a boolean or a timespan. When true,
<command>systemd-networkd
</command> retains
1087 both the static and dynamic configuration of the interface even if its carrier is lost. When
1088 false,
<command>systemd-networkd
</command> drops both the static and dynamic configuration of
1089 the interface. When a timespan is specified,
<command>systemd-networkd
</command> waits for
1090 the specified timespan, and ignores the carrier loss if the link regain its carrier within
1091 the timespan. Setting
0 seconds is equivalent to
<literal>no
</literal>, and
1092 <literal>infinite
</literal> is equivalent to
<literal>yes
</literal>.
</para>
1094 <para>Setting a finite timespan may be useful when e.g. in the following cases:
1097 <para>A wireless interface connecting to a network which has multiple access points with
1098 the same SSID.
</para>
1101 <para>Enslaving a wireless interface to a bond interface, which may disconnect from the
1102 connected access point and causes its carrier to be lost.
</para>
1105 <para>The driver of the interface resets when the MTU is changed.
</para>
1110 <para>When
<varname>Bond=
</varname> is specified to a wireless interface, defaults to
3
1111 seconds. When the DHCPv4 client is enabled and
<varname>UseMTU=
</varname> in the [DHCPv4]
1112 section enabled, defaults to
5 seconds. Otherwise, defaults to the value specified with
1113 <varname>ConfigureWithoutCarrier=
</varname>. When
<varname>ActivationPolicy=
</varname> is set
1114 to
<literal>always-up
</literal>, this is forced to
<literal>yes
</literal>, and ignored any
1115 user specified values.
</para>
1117 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
1122 <term><varname>KeepConfiguration=
</varname></term>
1124 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
1125 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
1126 will not drop static addresses and routes on starting up process. When set to
1127 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
1128 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
1129 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
1130 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
1131 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
1132 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
1133 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
1134 <literal>dhcp-on-stop
</literal> when
<command>systemd-networkd
</command> is running in
1135 initrd,
<literal>yes
</literal> when the root filesystem is a network filesystem, and
1136 <literal>no
</literal> otherwise.
</para>
1138 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
1145 <title>[Address] Section Options
</title>
1147 <para>An [Address] section accepts the following keys. Specify several [Address] sections to
1148 configure several addresses.
</para>
1150 <variablelist class='network-directives'
>
1152 <term><varname>Address=
</varname></term>
1154 <para>As in the [Network] section. This setting is mandatory. Each [Address] section can
1155 contain one
<varname>Address=
</varname> setting.
</para>
1157 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1162 <term><varname>Peer=
</varname></term>
1164 <para>The peer address in a point-to-point connection. Accepts the same format as the
1165 <varname>Address=
</varname> setting.
</para>
1167 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
1172 <term><varname>Broadcast=
</varname></term>
1174 <para>Takes an IPv4 address or boolean value. The address must be in the format described in
1175 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1176 If set to true, then the IPv4 broadcast address will be derived from the
1177 <varname>Address=
</varname> setting. If set to false, then the broadcast address will not be
1178 set. Defaults to true, except for wireguard interfaces, where it default to false.
</para>
1180 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1185 <term><varname>Label=
</varname></term>
1187 <para>Specifies the label for the IPv4 address. The label must be a
7-bit ASCII string with
1188 a length of
1…
15 characters. Defaults to unset.
</para>
1190 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1195 <term><varname>PreferredLifetime=
</varname></term>
1197 <para>Allows the default
"preferred lifetime" of the address to be overridden. Only three
1198 settings are accepted:
<literal>forever
</literal>,
<literal>infinity
</literal>, which is the
1199 default and means that the address never expires, and
<literal>0</literal>, which means that
1200 the address is considered immediately
"expired" and will not be used, unless explicitly
1201 requested. A setting of
<option>PreferredLifetime=
0</option> is useful for addresses which
1202 are added to be used only by a specific application, which is then configured to use them
1205 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
1210 <term><varname>Scope=
</varname></term>
1212 <para>The scope of the address, which can be
<literal>global
</literal> (valid everywhere on
1213 the network, even through a gateway),
<literal>link
</literal> (only valid on this device,
1214 will not traverse a gateway) or
<literal>host
</literal> (only valid within the device itself,
1215 e.g.
127.0.0.1) or an integer in the range
0…
255. Defaults to
<literal>global
</literal>.
1216 IPv4 only - IPv6 scope is automatically assigned by the kernel and cannot be set manually.
1219 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1224 <term><varname>RouteMetric=
</varname></term>
1226 <para>The metric of the prefix route, which is pointing to the subnet of the configured IP
1227 address, taking the configured prefix length into account. Takes an unsigned integer in the
1228 range
0…
4294967295. When unset or set to
0, the kernel's default value is used. This
1229 setting will be ignored when
<varname>AddPrefixRoute=
</varname> is false.
</para>
1231 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
1236 <term><varname>HomeAddress=
</varname></term>
1238 <para>Takes a boolean. Designates this address the
"home address" as defined in
1239 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>. Supported only on IPv6.
1240 Defaults to false.
</para>
1242 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1247 <term><varname>DuplicateAddressDetection=
</varname></term>
1249 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
<literal>both
</literal>,
1250 or
<literal>none
</literal>. When
<literal>ipv4
</literal>, performs IPv4 Address Conflict
1251 Detection. See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>.
1252 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
1253 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>. Defaults to
1254 <literal>ipv4
</literal> for IPv4 link-local addresses,
<literal>ipv6
</literal> for IPv6
1255 addresses, and
<literal>none
</literal> otherwise.
</para>
1257 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1262 <term><varname>ManageTemporaryAddress=
</varname></term>
1264 <para>Takes a boolean. If true the kernel manage temporary addresses created from this one as
1265 template on behalf of Privacy Extensions
1266 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become active,
1267 the use_tempaddr sysctl setting has to be set to a value greater than zero. The given address
1268 needs to have a prefix length of
64. This flag allows using privacy extensions in a manually
1269 configured network, just like if stateless auto-configuration was active. Defaults to false.
1272 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1277 <term><varname>AddPrefixRoute=
</varname></term>
1279 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
1280 Defaults to true.
</para>
1282 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
1287 <term><varname>AutoJoin=
</varname></term>
1289 <para>Takes a boolean. Joining multicast group on ethernet level via
1290 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
1291 IGMP snooping since the switch would not replicate multicast packets on ports that did not
1292 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
1293 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
1294 that enables them to do the required join. By extending
<command>ip address
</command> command
1295 with option
<literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS)
1296 vxlan interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
1297 Defaults to
<literal>no
</literal>.
</para>
1299 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1304 <term><varname>NetLabel=
</varname><replaceable>label
</replaceable></term>
1307 <para>This setting provides a method for integrating static and dynamic network configuration into
1308 Linux
<ulink url=
"https://docs.kernel.org/netlabel/index.html">NetLabel
</ulink> subsystem rules,
1309 used by
<ulink url=
"https://en.wikipedia.org/wiki/Linux_Security_Modules">Linux Security Modules
1310 (LSMs)
</ulink> for network access control. The label, with suitable LSM rules, can be used to
1311 control connectivity of (for example) a service with peers in the local network. At least with
1312 SELinux, only the ingress can be controlled but not egress. The benefit of using this setting is
1313 that it may be possible to apply interface independent part of NetLabel configuration at very early
1314 stage of system boot sequence, at the time when the network interfaces are not available yet, with
1316 project='man-pages'
><refentrytitle>netlabelctl
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1317 and the per-interface configuration with
<command>systemd-networkd
</command> once the interfaces
1318 appear later. Currently this feature is only implemented for SELinux.
</para>
1320 <para>The option expects a single NetLabel label. The label must conform to lexical restrictions of
1321 LSM labels. When an interface is configured with IP addresses, the addresses and subnetwork masks
1322 will be appended to the
<ulink
1323 url=
"https://github.com/SELinuxProject/selinux-notebook/blob/main/src/network_support.md">NetLabel
1324 Fallback Peer Labeling
</ulink> rules. They will be removed when the interface is
1325 deconfigured. Failures to manage the labels will be ignored.
</para>
1327 <para>Warning: Once labeling is enabled for network traffic, a lot of LSM access control points in
1328 Linux networking stack go from dormant to active. Care should be taken to avoid getting into a
1329 situation where for example remote connectivity is broken, when the security policy hasn't been
1330 updated to consider LSM per-packet access controls and no rules would allow any network
1331 traffic. Also note that additional configuration with
<citerefentry
1332 project='man-pages'
><refentrytitle>netlabelctl
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1336 <programlisting>[Address]
1337 NetLabel=system_u:object_r:localnet_peer_t:s0
</programlisting>
1339 With the example rules applying for interface
<literal>eth0
</literal>, when the interface is
1340 configured with an IPv4 address of
10.0.0.123/
8,
<command>systemd-networkd
</command> performs the
1341 equivalent of
<command>netlabelctl
</command> operation
1343 <programlisting>netlabelctl unlbl add interface eth0 address:
10.0.0.0/
8 label:system_u:object_r:localnet_peer_t:s0
</programlisting>
1345 and the reverse operation when the IPv4 address is deconfigured. The configuration can be used with
1346 LSM rules; in case of SELinux to allow a SELinux domain to receive data from objects of SELinux
1347 <literal>peer
</literal> class. For example:
1349 <programlisting>type localnet_peer_t;
1350 allow my_server_t localnet_peer_t:peer recv;
</programlisting>
1352 The effect of the above configuration and rules (in absence of other rules as may be the case) is
1353 to only allow
<literal>my_server_t
</literal> (and nothing else) to receive data from local subnet
1354 10.0.0.0/
8 of interface
<literal>eth0
</literal>.
1357 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
1362 <term><varname>NFTSet=
</varname><replaceable>source
</replaceable>:
<replaceable>family
</replaceable>:
<replaceable>table
</replaceable>:
<replaceable>set
</replaceable></term>
1364 <para>This setting provides a method for integrating network configuration into firewall rules with
1365 <ulink url=
"https://netfilter.org/projects/nftables/index.html">NFT
</ulink> sets. The benefit of
1366 using the setting is that static network configuration (or dynamically obtained network addresses,
1367 see similar directives in other sections) can be used in firewall rules with the indirection of NFT
1368 set types. For example, access could be granted for hosts in the local subnetwork only. Firewall
1369 rules using IP address of an interface are also instantly updated when the network configuration
1370 changes, for example via DHCP.
</para>
1372 <para>This option expects a whitespace separated list of NFT set definitions. Each definition
1373 consists of a colon-separated tuple of source type (one of
<literal>address
</literal>,
1374 <literal>prefix
</literal> or
<literal>ifindex
</literal>), NFT address family (one of
1375 <literal>arp
</literal>,
<literal>bridge
</literal>,
<literal>inet
</literal>,
<literal>ip
</literal>,
1376 <literal>ip6
</literal>, or
<literal>netdev
</literal>), table name and set name. The names of tables
1377 and sets must conform to lexical restrictions of NFT table names. The type of the element used in
1378 the NFT filter must match the type implied by the directive (
<literal>address
</literal>,
1379 <literal>prefix
</literal> or
<literal>ifindex
</literal>) and address type (IPv4 or IPv6) as shown
1380 in the table below.
</para>
1383 <title>Defined
<varname>source type
</varname> values
</title>
1385 <colspec colname='source type'
/>
1386 <colspec colname='description'
/>
1387 <colspec colname='NFT type name'
/>
1390 <entry>Source type
</entry>
1391 <entry>Description
</entry>
1392 <entry>Corresponding NFT type name
</entry>
1398 <entry><literal>address
</literal></entry>
1399 <entry>host IP address
</entry>
1400 <entry><literal>ipv4_addr
</literal> or
<literal>ipv6_addr
</literal></entry>
1403 <entry><literal>prefix
</literal></entry>
1404 <entry>network prefix
</entry>
1405 <entry><literal>ipv4_addr
</literal> or
<literal>ipv6_addr
</literal>, with
<literal>flags interval
</literal></entry>
1408 <entry><literal>ifindex
</literal></entry>
1409 <entry>interface index
</entry>
1410 <entry><literal>iface_index
</literal></entry>
1416 <para>When an interface is configured with IP addresses, the addresses, subnetwork masks or
1417 interface index will be appended to the NFT sets. The information will be removed when the
1418 interface is deconfigured.
<command>systemd-networkd
</command> only inserts elements to (or removes
1419 from) the sets, so the related NFT rules, tables and sets must be prepared elsewhere in
1420 advance. Failures to manage the sets will be ignored.
</para>
1423 <programlisting>[Address]
1424 NFTSet=prefix:netdev:filter:eth_ipv4_prefix
</programlisting>
1425 Corresponding NFT rules:
1426 <programlisting>table netdev filter {
1427 set eth_ipv4_prefix {
1432 type filter hook ingress device
"eth0" priority filter; policy drop;
1433 ip daddr != @eth_ipv4_prefix drop
1439 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
1446 <title>[Neighbor] Section Options
</title>
1448 <para>A [Neighbor] section accepts the following keys. The neighbor section adds a permanent,
1449 static entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the
1450 links matched for the network. Specify several [Neighbor] sections to configure several static
1453 <variablelist class='network-directives'
>
1455 <term><varname>Address=
</varname></term>
1457 <para>The IP address of the neighbor.
</para>
1459 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1464 <term><varname>LinkLayerAddress=
</varname></term>
1466 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
1468 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
1475 <title>[IPv6AddressLabel] Section Options
</title>
1477 <para>An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel]
1478 sections to configure several address labels. IPv6 address labels are used for address selection.
1479 See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>. Precedence is managed by
1480 userspace, and only the label itself is stored in the kernel.
</para>
1482 <variablelist class='network-directives'
>
1484 <term><varname>Label=
</varname></term>
1486 <para>The label for the prefix, an unsigned integer in the range
0…
4294967294.
0xffffffff is
1487 reserved. This setting is mandatory.
</para>
1489 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1494 <term><varname>Prefix=
</varname></term>
1496 <para>IPv6 prefix is an address with a prefix length, separated by a slash
1497 <literal>/
</literal> character. This setting is mandatory.
</para>
1499 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1506 <title>[RoutingPolicyRule] Section Options
</title>
1508 <para>An [RoutingPolicyRule] section accepts the following settings. Specify several
1509 [RoutingPolicyRule] sections to configure several rules.
</para>
1511 <variablelist class='network-directives'
>
1513 <term><varname>TypeOfService=
</varname></term>
1516 This specifies the Type of Service (ToS) field of packets to match;
1517 it takes an unsigned integer in the range
0…
255.
1518 The field can be used to specify precedence (the first
3 bits) and ToS (the next
3 bits).
1519 The field can be also used to specify Differentiated Services Code Point (DSCP) (the first
6 bits) and
1520 Explicit Congestion Notification (ECN) (the last
2 bits).
1521 See
<ulink url=
"https://en.wikipedia.org/wiki/Type_of_service">Type of Service
</ulink>
1522 and
<ulink url=
"https://en.wikipedia.org/wiki/Differentiated_services">Differentiated services
</ulink>
1526 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1531 <term><varname>From=
</varname></term>
1533 <para>Specifies the source address prefix to match. Possibly followed by a slash and the
1534 prefix length.
</para>
1536 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1541 <term><varname>To=
</varname></term>
1543 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the
1544 prefix length.
</para>
1546 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1551 <term><varname>FirewallMark=
</varname></term>
1553 <para>Specifies the iptables firewall mark value to match (a number in the range
1554 1…
4294967295). Optionally, the firewall mask (also a number between
1…
4294967295) can be
1555 suffixed with a slash (
<literal>/
</literal>), e.g.,
<literal>7/
255</literal>.
</para>
1557 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1562 <term><varname>Table=
</varname></term>
1564 <para>Specifies the routing table identifier to look up if the rule selector matches. Takes
1565 one of predefined names
<literal>default
</literal>,
<literal>main
</literal>, and
1566 <literal>local
</literal>, and names defined in
<varname>RouteTable=
</varname> in
1567 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1568 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1570 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1575 <term><varname>Priority=
</varname></term>
1577 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an integer in the
1578 range
0…
4294967295. Higher number means lower priority, and rules get processed in order of
1579 increasing number. Defaults to unset, and the kernel will pick a value dynamically.
</para>
1581 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1586 <term><varname>IncomingInterface=
</varname></term>
1588 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches
1589 packets originating from this host.
</para>
1591 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
1596 <term><varname>OutgoingInterface=
</varname></term>
1598 <para>Specifies the outgoing device to match. The outgoing interface is only available for
1599 packets originating from local sockets that are bound to a device.
</para>
1601 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
1606 <term><varname>SourcePort=
</varname></term>
1608 <para>Specifies the source IP port or IP port range match in forwarding information base
1609 (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
1610 Defaults to unset.
</para>
1612 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1617 <term><varname>DestinationPort=
</varname></term>
1619 <para>Specifies the destination IP port or IP port range match in forwarding information base
1620 (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
1621 Defaults to unset.
</para>
1623 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1628 <term><varname>IPProtocol=
</varname></term>
1630 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP
1631 protocol name such as
<literal>tcp
</literal>,
<literal>udp
</literal> or
1632 <literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
1633 <literal>tcp
</literal> or
<literal>17</literal> for
<literal>udp
</literal>. Defaults to unset.
1636 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1641 <term><varname>InvertRule=
</varname></term>
1643 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1645 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1650 <term><varname>Family=
</varname></term>
1652 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1653 <literal>both
</literal>. By default, the address family is determined by the address
1654 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1655 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1656 <literal>ipv4
</literal>.
</para>
1658 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
1663 <term><varname>User=
</varname></term>
1665 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1668 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
1673 <term><varname>SuppressPrefixLength=
</varname></term>
1675 <para>Takes a number
<replaceable>N
</replaceable> in the range
0…
128 and rejects routing
1676 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1679 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
1684 <term><varname>SuppressInterfaceGroup=
</varname></term>
1686 <para>Takes an integer in the range
0…
2147483647 and rejects routing decisions that have
1687 an interface with the same group id. It has the same meaning as
1688 <option>suppress_ifgroup
</option> in
<command>ip rule
</command>. Defaults to unset.
</para>
1690 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
1695 <term><varname>Type=
</varname></term>
1697 <para>Specifies Routing Policy Database (RPDB) rule type. Takes one of
1698 <literal>blackhole
</literal>,
<literal>unreachable
</literal> or
<literal>prohibit
</literal>.
1701 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1708 <title>[NextHop] Section Options
</title>
1710 <para>The [NextHop] section is used to manipulate entries in the kernel's
"nexthop" tables. The
1711 [NextHop] section accepts the following settings. Specify several [NextHop] sections to configure
1712 several hops.
</para>
1714 <variablelist class='network-directives'
>
1716 <term><varname>Id=
</varname></term>
1718 <para>The id of the next hop. Takes an integer in the range
1…
4294967295. If unspecified,
1719 then automatically chosen by kernel.
</para>
1721 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
1726 <term><varname>Gateway=
</varname></term>
1728 <para>As in the [Network] section.
</para>
1730 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
1735 <term><varname>Family=
</varname></term>
1737 <para>Takes one of the special values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>.
1738 By default, the family is determined by the address specified in
1739 <varname>Gateway=
</varname>. If
<varname>Gateway=
</varname> is not specified, then defaults
1740 to
<literal>ipv4
</literal>.
</para>
1742 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1747 <term><varname>OnLink=
</varname></term>
1749 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1750 reachable directly by the current machine (i.e., attached to the local network), so that we
1751 can insert the nexthop in the kernel table without it being complained about. Defaults to
1752 <literal>no
</literal>.
</para>
1754 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1759 <term><varname>Blackhole=
</varname></term>
1761 <para>Takes a boolean. If enabled, packets to the corresponding routes are discarded
1762 silently, and
<varname>Gateway=
</varname> cannot be specified. Defaults to
1763 <literal>no
</literal>.
</para>
1765 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1770 <term><varname>Group=
</varname></term>
1772 <para>Takes a whitespace separated list of nexthop IDs. Each ID must be in the range
1773 1…
4294967295. Optionally, each nexthop ID can take a weight after a colon
1774 (
<literal><replaceable>id
</replaceable><optional>:
<replaceable>weight
</replaceable></optional></literal>).
1775 The weight must be in the range
1…
255. If the weight is not specified, then it is assumed
1776 that the weight is
1. This setting cannot be specified with
<varname>Gateway=
</varname>,
1777 <varname>Family=
</varname>,
<varname>Blackhole=
</varname>. This setting can be specified
1778 multiple times. If an empty string is assigned, then the all previous assignments are
1779 cleared. Defaults to unset.
</para>
1781 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
1788 <title>[Route] Section Options
</title>
1790 <para>The [Route] section accepts the following settings. Specify several [Route] sections to
1791 configure several routes.
</para>
1793 <variablelist class='network-directives'
>
1795 <term><varname>Gateway=
</varname></term>
1797 <para>Takes the gateway address or the special values
<literal>_dhcp4
</literal> and
1798 <literal>_ipv6ra
</literal>. If
<literal>_dhcp4
</literal> or
<literal>_ipv6ra
</literal> is
1799 set, then the gateway address provided by DHCPv4 or IPv6 RA is used.
</para>
1801 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1806 <term><varname>GatewayOnLink=
</varname></term>
1808 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1809 reachable directly by the current machine (i.e., attached to the local network), so that we
1810 can insert the route in the kernel table without it being complained about. Defaults to
1811 <literal>no
</literal>.
</para>
1813 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1818 <term><varname>Destination=
</varname></term>
1820 <para>The destination prefix of the route. Possibly followed by a slash and the prefix
1821 length. If omitted, a full-length host route is assumed.
</para>
1823 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1828 <term><varname>Source=
</varname></term>
1830 <para>The source prefix of the route. Possibly followed by a slash and the prefix length. If
1831 omitted, a full-length host route is assumed.
</para>
1833 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
1838 <term><varname>Metric=
</varname></term>
1840 <para>The metric of the route. Takes an unsigned integer in the range
0…
4294967295. Defaults
1841 to unset, and the kernel's default will be used.
</para>
1843 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
1848 <term><varname>IPv6Preference=
</varname></term>
1850 <para>Specifies the route preference as defined in
1851 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink> for Router Discovery
1852 messages. Which can be one of
<literal>low
</literal> the route has a lowest priority,
1853 <literal>medium
</literal> the route has a default priority or
<literal>high
</literal> the
1854 route has a highest priority.
</para>
1856 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1861 <term><varname>Scope=
</varname></term>
1863 <para>The scope of the IPv4 route, which can be
<literal>global
</literal>,
1864 <literal>site
</literal>,
<literal>link
</literal>,
<literal>host
</literal>, or
1865 <literal>nowhere
</literal>:
</para>
1868 <para><literal>global
</literal> means the route can reach hosts more than one hop away.
1873 <para><literal>site
</literal> means an interior route in the local autonomous system.
1878 <para><literal>link
</literal> means the route can only reach hosts on the local network
1879 (one hop away).
</para>
1883 <para><literal>host
</literal> means the route will not leave the local machine (used for
1884 internal addresses like
127.0.0.1).
</para>
1888 <para><literal>nowhere
</literal> means the destination doesn't exist.
</para>
1892 <para>For IPv4 route, defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
1893 <literal>local
</literal> or
<literal>nat
</literal>, and
<literal>link
</literal> if
1894 <varname>Type=
</varname> is
<literal>broadcast
</literal>,
<literal>multicast
</literal>,
1895 <literal>anycast
</literal>, or
<literal>unicast
</literal>. In other cases,
1896 defaults to
<literal>global
</literal>. The value is not used for IPv6.
</para>
1898 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
1903 <term><varname>PreferredSource=
</varname></term>
1905 <para>The preferred source address of the route. The address must be in the format described
1907 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1910 <xi:include href=
"version-info.xml" xpointer=
"v227"/>
1915 <term><varname>Table=
</varname></term>
1917 <para>The table identifier for the route. Takes one of predefined names
1918 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
1919 defined in
<varname>RouteTable=
</varname> in
1920 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1921 or a number between
1 and
4294967295. The table can be retrieved using
1922 <command>ip route show table
<replaceable>num
</replaceable></command>. If unset and
1923 <varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1924 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1925 In other cases, defaults to
<literal>main
</literal>.
</para>
1927 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
1932 <term><varname>HopLimit=
</varname></term>
1934 <para>Configures per route hop limit. Takes an integer in the range
1…
255. See also
1935 <varname>IPv6HopLimit=
</varname>.
</para>
1937 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
1942 <term><varname>Protocol=
</varname></term>
1944 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special
1945 values
<literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1946 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1949 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1954 <term><varname>Type=
</varname></term>
1956 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1957 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1958 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1959 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1960 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e.
1961 a route indicating the path to take to a destination network address. If
1962 <literal>blackhole
</literal>, packets to the defined route are discarded silently. If
1963 <literal>unreachable
</literal>, packets to the defined route are discarded and the ICMP
1964 message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets to the
1965 defined route are discarded and the ICMP message
"Communication Administratively Prohibited"
1966 is generated. If
<literal>throw
</literal>, route lookup in the current routing table will
1967 fail and the route selection process will return to Routing Policy Database (RPDB). Defaults
1968 to
<literal>unicast
</literal>.
</para>
1970 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1975 <term><varname>InitialCongestionWindow=
</varname></term>
1977 <para>The TCP initial congestion window is used during the start of a TCP connection.
1978 During the start of a TCP session, when a client requests a resource, the server's initial
1979 congestion window determines how many packets will be sent during the initial burst of data
1980 without waiting for acknowledgement. Takes a number between
1 and
1023. Note that
100 is
1981 considered an extremely large value for this option. When unset, the kernel's default
1982 (typically
10) will be used.
</para>
1984 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
1989 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1991 <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
1992 that can initially be buffered at one time on a connection. The sending host can send only
1993 that amount of data before waiting for an acknowledgment and window update from the
1994 receiving host. Takes a number between
1 and
1023. Note that
100 is considered an extremely
1995 large value for this option. When unset, the kernel's default will be used.
</para>
1997 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
2002 <term><varname>QuickAck=
</varname></term>
2004 <para>Takes a boolean. When true, the TCP quick ACK mode for the route is enabled. When unset,
2005 the kernel's default will be used.
</para>
2007 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
2012 <term><varname>FastOpenNoCookie=
</varname></term>
2014 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
2015 When unset, the kernel's default will be used.
</para>
2017 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2022 <term><varname>TTLPropagate=
</varname></term>
2024 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
2025 When unset, the kernel's default will be used.
</para>
2027 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2032 <term><varname>MTUBytes=
</varname></term>
2034 <para>The maximum transmission unit in bytes to set for the route. The usual suffixes K, M,
2035 G, are supported and are understood to the base of
1024.
</para>
2037 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
2042 <term><varname>TCPAdvertisedMaximumSegmentSize=
</varname></term>
2044 <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G,
2045 are supported and are understood to the base of
1024. An unsigned integer in the range
2046 1…
4294967294. When unset, the kernel's default will be used.
</para>
2048 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2053 <term><varname>TCPCongestionControlAlgorithm=
</varname></term>
2055 <para>Specifies the TCP congestion control algorithm for the route. Takes a name of the algorithm,
2056 e.g.
<literal>bbr
</literal>,
<literal>dctcp
</literal>, or
<literal>vegas
</literal>. When unset,
2057 the kernel's default will be used.
</para>
2059 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2064 <term><varname>TCPRetransmissionTimeoutSec=
</varname></term>
2066 <para>Specifies the TCP Retransmission Timeout (RTO) for the route. Takes time values in seconds.
2067 This value specifies the timeout of an alive TCP connection, when retransmissions remain
2068 unacknowledged. When unset, the kernel's default will be used.
</para>
2070 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2075 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
2077 <para>Configures multipath route. Multipath routing is the technique of using multiple
2078 alternative paths through a network. Takes gateway address. Optionally, takes a network
2079 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for this
2080 multipath route separated with whitespace. This setting can be specified multiple times. If
2081 an empty string is assigned, then the all previous assignments are cleared.
</para>
2083 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2088 <term><varname>NextHop=
</varname></term>
2090 <para>Specifies the nexthop id. Takes an unsigned integer in the range
1…
4294967295. If set,
2091 the corresponding [NextHop] section must be configured. Defaults to unset.
</para>
2093 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2100 <title>[DHCPv4] Section Options
</title>
2102 <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
2103 <varname>DHCP=
</varname> setting described above:
</para>
2105 <variablelist class='network-directives'
>
2107 <!-- DHCP packet contents -->
2110 <term><varname>RequestAddress=
</varname></term>
2112 <para>Takes an IPv4 address. When specified, the Requested IP Address option (option code
50) is
2113 added with it to the initial DHCPDISCOVER message sent by the DHCP client. Defaults to unset, and
2114 an already assigned dynamic address to the interface is automatically picked.
</para>
2116 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2121 <term><varname>SendHostname=
</varname></term>
2123 <para>When true (the default), the machine's hostname (or the value specified with
2124 <varname>Hostname=
</varname>, described below) will be sent to the DHCP server. Note that the
2125 hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and be
2126 formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option
2129 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
2134 <term><varname>Hostname=
</varname></term>
2136 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's
2137 hostname. Note that the specified hostname must consist only of
7-bit ASCII lower-case
2138 characters and no spaces or dots, and be formatted as a valid DNS domain name.
</para>
2140 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
2145 <term><varname>MUDURL=
</varname></term>
2147 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent
2148 to the DHCPv4 server. Takes a URL of length up to
255 characters. A superficial verification
2149 that the string is a valid URL will be performed. DHCPv4 clients are intended to have at most
2150 one MUD URL associated with them. See
2151 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
2153 <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers
2154 to advertise device specifications, including the intended communication patterns for their
2155 device when it connects to the network. The network can then use this to author a
2156 context-specific access policy, so the device functions only within those parameters.
</para>
2158 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2163 <term><varname>ClientIdentifier=
</varname></term>
2165 <para>The DHCPv4 client identifier to use. Takes one of
<option>mac
</option> or
2166 <option>duid
</option>. If set to
<option>mac
</option>, the MAC address of the link is used. If set
2167 to
<option>duid
</option>, an RFC4361-compliant Client ID, which is the combination of IAID and
2168 DUID, is used. IAID can be configured by
<varname>IAID=
</varname>. DUID can be configured by
2169 <varname>DUIDType=
</varname> and
<varname>DUIDRawData=
</varname>. Defaults to
2170 <option>duid
</option>.
</para>
2172 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
2177 <term><varname>VendorClassIdentifier=
</varname></term>
2179 <para>The vendor class identifier used to identify vendor type and configuration.
</para>
2181 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2186 <term><varname>UserClass=
</varname></term>
2188 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or
2189 applications it represents. The information contained in this option is a string that
2190 represents the user class of which the client is a member. Each class sets an identifying
2191 string of information to be used by the DHCP service to classify clients. Takes a
2192 whitespace-separated list of strings.
</para>
2194 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
2199 <term><varname>DUIDType=
</varname></term>
2201 <para>Override the global
<varname>DUIDType=
</varname> setting for this network. See
2202 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2203 for a description of possible values.
</para>
2205 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2210 <term><varname>DUIDRawData=
</varname></term>
2212 <para>Override the global
<varname>DUIDRawData=
</varname> setting for this network. See
2213 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2214 for a description of possible values.
</para>
2216 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2221 <term><varname>IAID=
</varname></term>
2223 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned
2226 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2231 <term><varname>RapidCommit=
</varname></term>
2233 <para>Takes a boolean. The DHCPv4 client can obtain configuration parameters from a DHCPv4 server
2234 through a rapid two-message exchange (discover and ack). When the rapid commit option is set by
2235 both the DHCPv4 client and the DHCPv4 server, the two-message exchange is used. Otherwise, the
2236 four-message exchange (discover, offer, request, and ack) is used. The two-message exchange
2237 provides faster client configuration. See
2238 <ulink url=
"https://tools.ietf.org/html/rfc4039">RFC
4039</ulink> for details.
2239 Defaults to true.
</para>
2241 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2246 <term><varname>Anonymize=
</varname></term>
2248 <para>Takes a boolean. When true, the options sent to the DHCP server will follow the
2249 <ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink> (Anonymity Profiles for
2250 DHCP Clients) to minimize disclosure of identifying information. Defaults to false.
</para>
2252 <para>This option should only be set to true when
<varname>MACAddressPolicy=
</varname> is set
2253 to
<option>random
</option> (see
2254 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
2258 <varname>ClientIdentifier=mac
</varname>,
2259 <varname>SendHostname=no
</varname>,
2260 <varname>Use6RD=no
</varname>,
2261 <varname>UseCaptivePortal=no
</varname>,
2262 <varname>UseMTU=no
</varname>,
2263 <varname>UseNTP=no
</varname>,
2264 <varname>UseSIP=no
</varname>, and
2265 <varname>UseTimezone=no
</varname>
2266 are implied and these settings in the .network file are silently ignored. Also,
2267 <varname>Hostname=
</varname>,
2268 <varname>MUDURL=
</varname>,
2269 <varname>RequestAddress
</varname>,
2270 <varname>RequestOptions=
</varname>,
2271 <varname>SendOption=
</varname>,
2272 <varname>SendVendorOption=
</varname>,
2273 <varname>UserClass=
</varname>, and
2274 <varname>VendorClassIdentifier=
</varname>
2275 are silently ignored.
</para>
2277 <para>With this option enabled DHCP requests will mimic those generated by Microsoft
2278 Windows, in order to reduce the ability to fingerprint and recognize installations. This
2279 means DHCP request sizes will grow and lease data will be more comprehensive than normally,
2280 though most of the requested data is not actually used.
</para>
2282 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
2287 <term><varname>RequestOptions=
</varname></term>
2289 <para>Sets request options to be sent to the server in the DHCPv4 request options list. A
2290 whitespace-separated list of integers in the range
1…
254. Defaults to unset.
</para>
2292 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2297 <term><varname>SendOption=
</varname></term>
2299 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data
2300 type and data separated with a colon
2301 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2302 The option number must be an integer in the range
1…
254. The type takes one of
2303 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
2304 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
2305 string may be escaped using
2306 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2307 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2308 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
2310 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2315 <term><varname>SendVendorOption=
</varname></term>
2317 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data
2318 type and data separated with a colon
2319 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2320 The option number must be an integer in the range
1…
254. The type takes one of
2321 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
2322 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
2323 string may be escaped using
2324 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2325 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2326 then all options specified earlier are cleared. Defaults to unset.
</para>
2328 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2333 <term><varname>IPServiceType=
</varname></term>
2335 <para>Takes one of the special values
<literal>none
</literal>,
<literal>CS6
</literal>, or
2336 <literal>CS4
</literal>. When
<literal>none
</literal> no IP service type is set to the packet
2337 sent from the DHCPv4 client. When
<literal>CS6
</literal> (network control) or
2338 <literal>CS4
</literal> (realtime), the corresponding service type will be set. Defaults to
2339 <literal>CS6
</literal>.
</para>
2341 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2346 <term><varname>SocketPriority=
</varname></term>
2348 <para>The Linux socket option
<constant>SO_PRIORITY
</constant> applied to the raw IP socket used for
2349 initial DHCPv4 messages. Unset by default. Usual values range from
0 to
6.
2350 More details about
<constant>SO_PRIORITY
</constant> socket option in
2351 <citerefentry project='man-pages'
><refentrytitle>socket
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
2352 Can be used in conjunction with [VLAN] section
<varname>EgressQOSMaps=
</varname> setting of .netdev
2353 file to set the
802.1Q VLAN ethernet tagged header priority, see
2354 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2357 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
2361 <!-- How to use the DHCP lease -->
2364 <term><varname>Label=
</varname></term>
2366 <para>Specifies the label for the IPv4 address received from the DHCP server. The label must
2367 be a
7-bit ASCII string with a length of
1…
15 characters. Defaults to unset.
</para>
2369 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2374 <term><varname>UseDNS=
</varname></term>
2376 <para>When true (the default), the DNS servers received from the DHCP server will be used.
2379 <para>This corresponds to the
<option>nameserver
</option> option in
2380 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2383 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2388 <term><varname>RoutesToDNS=
</varname></term>
2390 <para>When true, the routes to the DNS servers received from the DHCP server will be
2391 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored. Defaults to
2394 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2399 <term><varname>UseNTP=
</varname></term>
2401 <para>When true (the default), the NTP servers received from the DHCP server will be used by
2402 <filename>systemd-timesyncd.service
</filename>.
</para>
2404 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
2409 <term><varname>RoutesToNTP=
</varname></term>
2411 <para>When true, the routes to the NTP servers received from the DHCP server will be
2412 configured. When
<varname>UseNTP=
</varname> is disabled, this setting is ignored. Defaults to
2415 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
2420 <term><varname>UseSIP=
</varname></term>
2422 <para>When true (the default), the SIP servers received from the DHCP server will be collected
2423 and made available to client programs.
</para>
2425 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2430 <term><varname>UseCaptivePortal=
</varname></term>
2432 <para>When true (the default), the captive portal advertised by the DHCP server will be recorded
2433 and made available to client programs and displayed in the networkctl status output per-link.
</para>
2435 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
2440 <term><varname>UseMTU=
</varname></term>
2442 <para>When true, the interface maximum transmission unit from the DHCP server will be used on
2443 the current link. If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
2444 Defaults to false.
</para>
2446 <para>Note, some drivers will reset the interfaces if the MTU is changed. For such
2447 interfaces, please try to use
<varname>IgnoreCarrierLoss=
</varname> with a short timespan,
2448 e.g.
<literal>3 seconds
</literal>.
</para>
2450 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2455 <term><varname>UseHostname=
</varname></term>
2457 <para>When true (the default), the hostname received from the DHCP server will be set as the
2458 transient hostname of the system.
</para>
2460 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2465 <term><varname>UseDomains=
</varname></term>
2467 <para>Takes a boolean, or the special value
<option>route
</option>. When true, the domain name
2468 received from the DHCP server will be used as DNS search domain over this link, similarly to the
2469 effect of the
<option>Domains=
</option> setting. If set to
<option>route
</option>, the domain name
2470 received from the DHCP server will be used for routing DNS queries only, but not for searching,
2471 similarly to the effect of the
<option>Domains=
</option> setting when the argument is prefixed with
2472 <literal>~
</literal>. Defaults to false.
</para>
2474 <para>It is recommended to enable this option only on trusted networks, as setting this
2475 affects resolution of all hostnames, in particular of single-label names. It is generally
2476 safer to use the supplied domain only as routing domain, rather than as search domain, in
2477 order to not have it affect local resolution of single-label names.
</para>
2479 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
2480 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2483 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2488 <term><varname>UseRoutes=
</varname></term>
2490 <para>When true (the default), the static routes will be requested from the DHCP server and
2491 added to the routing table with a metric of
1024, and a scope of
<option>global
</option>,
2492 <option>link
</option> or
<option>host
</option>, depending on the route's destination and
2493 gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the link's
2494 own address, the scope will be set to
<option>host
</option>. Otherwise if the gateway is null
2495 (a direct route), a
<option>link
</option> scope will be used. For anything else, scope
2496 defaults to
<option>global
</option>.
</para>
2498 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
2503 <term><varname>RouteMetric=
</varname></term>
2505 <para>Set the routing metric for routes specified by the DHCP server (including the prefix
2506 route added for the specified prefix). Takes an unsigned integer in the range
0…
4294967295.
2507 Defaults to
1024.
</para>
2509 <xi:include href=
"version-info.xml" xpointer=
"v217"/>
2514 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
2516 <para>The table identifier for DHCP routes. Takes one of predefined names
2517 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
2518 defined in
<varname>RouteTable=
</varname> in
2519 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2520 or a number between
1…
4294967295.
</para>
2522 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
2523 used when this parameter is not specified.
</para>
2525 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
2530 <term><varname>RouteMTUBytes=
</varname></term>
2532 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further
2535 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2540 <term><varname>QuickAck=
</varname></term>
2542 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
2543 the acquired DHCPv4 lease. When unset, the kernel's default will be used.
</para>
2545 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
2550 <term><varname>InitialCongestionWindow=
</varname></term>
2552 <para>As in the [Route] section.
</para>
2554 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2559 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
2561 <para>As in the [Route] section.
</para>
2563 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2568 <term><varname>UseGateway=
</varname></term>
2570 <para>When true, and the DHCP server provides a Router option, the default gateway based on the
2571 router address will be configured. Defaults to unset, and the value specified with
2572 <varname>UseRoutes=
</varname> will be used.
</para>
2574 <para>Note, when the server provides both the Router and Classless Static Routes option, and
2575 <varname>UseRoutes=
</varname> is enabled, the Router option is always ignored regardless of this
2576 setting. See
<ulink url=
"https://datatracker.ietf.org/doc/html/rfc3442">RFC
3442</ulink>.
</para>
2578 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2583 <term><varname>UseTimezone=
</varname></term>
2584 <listitem><para>When true, the timezone received from the DHCP server will be set as timezone
2585 of the local system. Defaults to false.
</para>
2587 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
2591 <term><varname>Use6RD=
</varname></term>
2593 <para>When true, subnets of the received IPv6 prefix are assigned to downstream interfaces
2594 which enables
<varname>DHCPPrefixDelegation=
</varname>. See also
2595 <varname>DHCPPrefixDelegation=
</varname> in the [Network] section, the [DHCPPrefixDelegation]
2596 section, and
<ulink url=
"https://tools.ietf.org/html/rfc5969">RFC
5969</ulink>. Defaults to
2599 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2604 <term><varname>IPv6OnlyMode=
</varname></term>
2606 <para>When true, the DHCPv4 configuration will be delayed by the timespan provided by the DHCP
2607 server and skip to configure dynamic IPv4 network connectivity if IPv6 connectivity is provided
2608 within the timespan. See
<ulink url=
"https://tools.ietf.org/html/rfc8925">RFC
8925</ulink>.
2609 Defaults to true when
<varname>IPv6AcceptRA=
</varname> is enabled or DHCPv6 client is enabled
2610 (i.e.,
<varname>DHCP=yes
</varname>), and false otherwise.
</para>
2612 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2617 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
2619 <para>Allows one to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease
2620 lifetime. Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal>. If
2621 specified, the acquired address never expires. Defaults to unset.
</para>
2623 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2627 <!-- How to communicate with the server -->
2630 <term><varname>RequestBroadcast=
</varname></term>
2632 <para>Request the server to use broadcast messages before the IP address has been configured.
2633 This is necessary for devices that cannot receive RAW packets, or that cannot receive packets
2634 at all before an IP address has been configured. On the other hand, this must not be enabled
2635 on networks where broadcasts are filtered out.
</para>
2637 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2642 <term><varname>MaxAttempts=
</varname></term>
2644 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
2645 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>. Note that the
2646 time between retries is increased exponentially, up to approximately one per minute, so the
2647 network will not be overloaded even if this number is high. The default is suitable in most
2648 circumstances.
</para>
2650 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2655 <term><varname>ListenPort=
</varname></term>
2657 <para>Set the port from which the DHCP client packets originate.
</para>
2659 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
2664 <term><varname>DenyList=
</varname></term>
2666 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2667 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are rejected.
2668 Note that if
<varname>AllowList=
</varname> is configured then
<varname>DenyList=
</varname> is
2671 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2676 <term><varname>AllowList=
</varname></term>
2678 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2679 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are accepted.
2682 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2687 <term><varname>SendRelease=
</varname></term>
2689 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops. Defaults to
2692 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2697 <term><varname>SendDecline=
</varname></term>
2699 <para>A boolean. When true,
<command>systemd-networkd
</command> performs IPv4 Duplicate
2700 Address Detection to the acquired address by the DHCPv4 client. If duplicate is detected,
2701 the DHCPv4 client rejects the address by sending a
<constant>DHCPDECLINE
</constant> packet to
2702 the DHCP server, and tries to obtain an IP address again. See
2703 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>. Defaults to false.
</para>
2705 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2710 <term><varname>NetLabel=
</varname></term>
2712 <para>This applies the NetLabel for the addresses received with DHCP, like
2713 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
2714 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
2716 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2721 <term><varname>NFTSet=
</varname></term>
2723 <para>This applies the NFT set for the network configuration received with DHCP, like
2724 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
2725 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
2726 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
2727 <literal>ipv4_addr
</literal>.
</para>
2729 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2736 <title>[DHCPv6] Section Options
</title>
2738 <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
2739 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
2742 <variablelist class='network-directives'
>
2744 <!-- DHCP packet contents -->
2747 <term><varname>MUDURL=
</varname></term>
2748 <term><varname>IAID=
</varname></term>
2749 <term><varname>DUIDType=
</varname></term>
2750 <term><varname>DUIDRawData=
</varname></term>
2751 <term><varname>RequestOptions=
</varname></term>
2753 <para>As in the [DHCPv4] section.
</para>
2755 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2760 <term><varname>SendOption=
</varname></term>
2762 <para>As in the [DHCPv4] section, however because DHCPv6 uses
16-bit fields to store option
2763 numbers, the option number is an integer in the range
1…
65536.
</para>
2765 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2770 <term><varname>SendVendorOption=
</varname></term>
2772 <para>Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier,
2773 DHCP option number, data type, and data separated with a colon
2774 (
<literal><replaceable>enterprise identifier
</replaceable>:
<replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2775 Enterprise identifier is an unsigned integer in the range
1…
4294967294. The option number
2776 must be an integer in the range
1…
254. Data type takes one of
<literal>uint8
</literal>,
2777 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
2778 <literal>ipv6address
</literal>, or
<literal>string
</literal>. Special characters in the data
2779 string may be escaped using
2780 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2781 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2782 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
2784 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2789 <term><varname>UserClass=
</varname></term>
2791 <para>A DHCPv6 client can use User Class option to identify the type or category of user or
2792 applications it represents. The information contained in this option is a string that
2793 represents the user class of which the client is a member. Each class sets an identifying
2794 string of information to be used by the DHCP service to classify clients. Special characters
2795 in the data string may be escaped using
2796 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2797 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2798 specified, then all options specified earlier are cleared. Takes a whitespace-separated list
2799 of strings. Note that currently
<constant>NUL
</constant> bytes are not allowed.
</para>
2801 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2806 <term><varname>VendorClass=
</varname></term>
2808 <para>A DHCPv6 client can use VendorClass option to identify the vendor that manufactured the
2809 hardware on which the client is running. The information contained in the data area of this
2810 option is contained in one or more opaque fields that identify details of the hardware
2811 configuration. Takes a whitespace-separated list of strings.
</para>
2813 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2818 <term><varname>PrefixDelegationHint=
</varname></term>
2820 <para>Takes an IPv6 address with prefix length in the same format as the
2821 <varname>Address=
</varname> in the [Network] section. The DHCPv6 client will include a prefix
2822 hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
2823 1…
128. Defaults to unset.
</para>
2825 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2830 <term><varname>RapidCommit=
</varname></term>
2832 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server
2833 through a rapid two-message exchange (solicit and reply). When the rapid commit option is set by
2834 both the DHCPv6 client and the DHCPv6 server, the two-message exchange is used. Otherwise, the
2835 four-message exchange (solicit, advertise, request, and reply) is used. The two-message exchange
2836 provides faster client configuration. See
2837 <ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
2838 Defaults to true, and the two-message exchange will be used if the server support it.
</para>
2840 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2845 <term><varname>SendHostname=
</varname></term>
2847 <para>When true (the default), the machine's hostname (or the value specified with
2848 <varname>Hostname=
</varname>, described below) will be sent to the DHCPv6 server. Note that the
2849 hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and be
2850 formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option
2853 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2858 <term><varname>Hostname=
</varname></term>
2860 <para>Use this value for the hostname which is sent to the DHCPv6 server, instead of machine's
2861 hostname. Note that the specified hostname must consist only of
7-bit ASCII lower-case
2862 characters and no spaces or dots, and be formatted as a valid DNS domain name.
</para>
2864 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2868 <!-- How to use the DHCP lease -->
2871 <term><varname>UseAddress=
</varname></term>
2873 <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
2876 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2881 <term><varname>UseCaptivePortal=
</varname></term>
2883 <para>When true (the default), the captive portal advertised by the DHCPv6 server will be recorded
2884 and made available to client programs and displayed in the networkctl status output per-link.
</para>
2886 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
2891 <term><varname>UseDelegatedPrefix=
</varname></term>
2893 <para>When true (the default), the client will request the DHCPv6 server to delegate
2894 prefixes. If the server provides prefixes to be delegated, then subnets of the prefixes are
2895 assigned to the interfaces that have
<varname>DHCPPrefixDelegation=yes
</varname>.
2896 See also the
<varname>DHCPPrefixDelegation=
</varname> setting in the [Network] section,
2897 settings in the [DHCPPrefixDelegation] section, and
2898 <ulink url=
"https://www.rfc-editor.org/rfc/rfc8415.html#section-6.3">RFC
8415</ulink>.
2901 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2906 <term><varname>UseDNS=
</varname></term>
2907 <term><varname>UseNTP=
</varname></term>
2908 <term><varname>UseHostname=
</varname></term>
2909 <term><varname>UseDomains=
</varname></term>
2910 <term><varname>NetLabel=
</varname></term>
2911 <term><varname>SendRelease=
</varname></term>
2913 <para>As in the [DHCPv4] section.
</para>
2915 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2920 <term><varname>NFTSet=
</varname></term>
2922 <para>This applies the NFT set for the network configuration received with DHCP, like
2923 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
2924 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal>
2925 or
<literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
2926 <literal>ipv6_addr
</literal>.
</para>
2928 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2932 <!-- How to communicate with the server -->
2935 <term><varname>WithoutRA=
</varname></term>
2937 <para>Allows DHCPv6 client to start without router advertisements's
2938 <literal>managed
</literal> or
<literal>other configuration
</literal> flag. Takes one of
2939 <literal>no
</literal>,
<literal>solicit
</literal>, or
2940 <literal>information-request
</literal>. If this is not specified,
2941 <literal>solicit
</literal> is used when
<varname>DHCPPrefixDelegation=
</varname> is enabled
2942 and
<varname>UplinkInterface=:self
</varname> is specified in the [DHCPPrefixDelegation]
2943 section. Otherwise, defaults to
<literal>no
</literal>, and the DHCPv6 client will be started
2944 when an RA is received. See also the
<varname>DHCPv6Client=
</varname> setting in the
2945 [IPv6AcceptRA] section.
</para>
2947 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2954 <title>[DHCPPrefixDelegation] Section Options
</title>
2955 <para>The [DHCPPrefixDelegation] section configures subnet prefixes of the delegated prefixes
2956 acquired by a DHCPv6 client or by a DHCPv4 client through the
6RD option on another interface.
2957 The settings in this section are used only when the
<varname>DHCPPrefixDelegation=
</varname>
2958 setting in the [Network] section is enabled.
</para>
2960 <variablelist class='network-directives'
>
2962 <term><varname>UplinkInterface=
</varname></term>
2964 <para>Specifies the name or the index of the uplink interface, or one of the special values
2965 <literal>:self
</literal> and
<literal>:auto
</literal>. When
<literal>:self
</literal>, the
2966 interface itself is considered the uplink interface, and
2967 <varname>WithoutRA=solicit
</varname> is implied if the setting is not explicitly specified.
2968 When
<literal>:auto
</literal>, the first link which acquired prefixes to be delegated from
2969 the DHCPv6 or DHCPv4 server is selected. Defaults to
<literal>:auto
</literal>.
</para>
2971 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2976 <term><varname>SubnetId=
</varname></term>
2978 <para>Configure a specific subnet ID on the interface from a (previously) received prefix
2979 delegation. You can either set
"auto" (the default) or a specific subnet ID (as defined in
2980 <ulink url=
"https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC
4291</ulink>, section
2981 2.5.4), in which case the allowed value is hexadecimal, from
0 to
0x7fffffffffffffff
2984 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2989 <term><varname>Announce=
</varname></term>
2991 <para>Takes a boolean. When enabled, and
<varname>IPv6SendRA=
</varname> in [Network] section
2992 is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
2993 This setting will be ignored when the
<varname>DHCPPrefixDelegation=
</varname> setting is
2994 enabled on the upstream interface. Defaults to yes.
</para>
2996 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
3001 <term><varname>Assign=
</varname></term>
3003 <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
3004 are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
3005 interface), the EUI-
64 algorithm will be used by default to form an interface identifier from
3006 the delegated prefixes. See also
<varname>Token=
</varname> setting below. Defaults to yes.
3009 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3014 <term><varname>Token=
</varname></term>
3016 <para>Specifies an optional address generation mode for assigning an address in each
3017 delegated prefix. This accepts the same syntax as
<varname>Token=
</varname> in the
3018 [IPv6AcceptRA] section. If
<varname>Assign=
</varname> is set to false, then this setting will
3019 be ignored. Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
3021 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3026 <term><varname>ManageTemporaryAddress=
</varname></term>
3028 <para>As in the [Address] section, but defaults to true.
</para>
3030 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3035 <term><varname>RouteMetric=
</varname></term>
3037 <para>The metric of the route to the delegated prefix subnet. Takes an unsigned integer in
3038 the range
0…
4294967295. When set to
0, the kernel's default value is used. Defaults to
256.
3041 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3046 <term><varname>NetLabel=
</varname></term>
3048 <para>This applies the NetLabel for the addresses received with DHCP, like
3049 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
3050 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
3052 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
3057 <term><varname>NFTSet=
</varname></term>
3059 <para>This applies the NFT set for the network configuration received with DHCP, like
3060 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
3061 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
3062 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
3063 <literal>ipv6_addr
</literal>.
</para>
3065 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3072 <title>[IPv6AcceptRA] Section Options
</title>
3073 <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
3074 with the
<varname>IPv6AcceptRA=
</varname> setting described above:
</para>
3076 <variablelist class='network-directives'
>
3078 <term><varname>Token=
</varname></term>
3080 <para>Specifies an optional address generation mode for the Stateless Address
3081 Autoconfiguration (SLAAC). The following values are supported:
</para>
3085 <term><option>eui64
</option></term>
3088 The EUI-
64 algorithm will be used to generate an address for that prefix. Only
3089 supported by Ethernet or InfiniBand interfaces.
3092 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3096 <term><option>static:
<replaceable>ADDRESS
</replaceable></option></term>
3099 An IPv6 address must be specified after a colon (
<literal>:
</literal>), and the
3100 lower bits of the supplied address are combined with the upper bits of a prefix
3101 received in a Router Advertisement (RA) message to form a complete address. Note
3102 that if multiple prefixes are received in an RA message, or in multiple RA messages,
3103 addresses will be formed from each of them using the supplied address. This mode
3104 implements SLAAC but uses a static interface identifier instead of an identifier
3105 generated by using the EUI-
64 algorithm. Because the interface identifier is static,
3106 if Duplicate Address Detection detects that the computed address is a duplicate
3107 (in use by another node on the link), then this mode will fail to provide an address
3108 for that prefix. If an IPv6 address without mode is specified, then
3109 <literal>static
</literal> mode is assumed.
3112 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3116 <term><option>prefixstable[:
<replaceable>ADDRESS
</replaceable>][,
<replaceable>UUID
</replaceable>]
</option></term>
3119 The algorithm specified in
3120 <ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink> will be used to
3121 generate interface identifiers. This mode can optionally take an IPv6 address
3122 separated with a colon (
<literal>:
</literal>). If an IPv6 address is specified,
3123 then an interface identifier is generated only when a prefix received in an RA
3124 message matches the supplied address.
3127 This mode can also optionally take a non-null UUID in the format which
3128 <function>sd_id128_from_string()
</function> accepts, e.g.
3129 <literal>86b123b969ba4b7eb8b3d8605123525a
</literal> or
3130 <literal>86b123b9-
69ba-
4b7e-b8b3-d8605123525a
</literal>. If a UUID is specified, the
3131 value is used as the secret key to generate interface identifiers. If not specified,
3132 then an application specific ID generated with the system's machine-ID will be used
3133 as the secret key. See
3134 <citerefentry><refentrytitle>sd-id128
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
3135 <citerefentry><refentrytitle>sd_id128_from_string
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
3137 <citerefentry><refentrytitle>sd_id128_get_machine
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
3140 Note that the
<literal>prefixstable
</literal> algorithm uses both the interface
3141 name and MAC address as input to the hash to compute the interface identifier, so
3142 if either of those are changed the resulting interface identifier (and address)
3143 will be changed, even if the prefix received in the RA message has not been
3147 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3152 <para>If no address generation mode is specified (which is the default), or a received
3153 prefix does not match any of the addresses provided in
<literal>prefixstable
</literal>
3154 mode, then the EUI-
64 algorithm will be used for Ethernet or InfiniBand interfaces,
3155 otherwise
<literal>prefixstable
</literal> will be used to form an interface identifier for
3158 <para>This setting can be specified multiple times. If an empty string is assigned, then
3159 the all previous assignments are cleared.
</para>
3162 <programlisting>Token=eui64
3164 Token=static:::
1a:
2b:
3c:
4d
3166 Token=prefixstable:
2002:da8:
1::
</programlisting></para>
3168 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3173 <term><varname>UseDNS=
</varname></term>
3175 <para>When true (the default), the DNS servers received in the Router Advertisement will be used.
</para>
3177 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
3178 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3180 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
3185 <term><varname>UseDomains=
</varname></term>
3187 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
3188 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link,
3189 similarly to the effect of the
<option>Domains=
</option> setting. If set to
3190 <literal>route
</literal>, the domain name received via IPv6 RA will be used for routing DNS queries
3191 only, but not for searching, similarly to the effect of the
<option>Domains=
</option> setting when
3192 the argument is prefixed with
<literal>~
</literal>. Defaults to false.
</para>
3194 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
3195 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
3196 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
3197 single-label names.
</para>
3199 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
3200 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3202 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
3207 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
3209 <para>The table identifier for the routes received in the Router Advertisement. Takes one of
3210 predefined names
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
3211 and names defined in
<varname>RouteTable=
</varname> in
3212 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3213 or a number between
1…
4294967295.
</para>
3215 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
3216 used when this parameter is not specified.
</para>
3218 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
3223 <term><varname>RouteMetric=
</varname></term>
3225 <para>Set the routing metric for the routes received in the Router Advertisement. Takes an unsigned
3226 integer in the range
0…
4294967295, or three unsigned integer separated with
<literal>:
</literal>,
3227 in that case the first one is used when the router preference is high, the second is for medium
3228 preference, and the last is for low preference
3229 (
<literal><replaceable>high
</replaceable>:
<replaceable>medium
</replaceable>:
<replaceable>low
</replaceable></literal>).
3230 Defaults to
<literal>512:
1024:
2048</literal>.
</para>
3232 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3237 <term><varname>QuickAck=
</varname></term>
3239 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
3240 the received RAs. When unset, the kernel's default will be used.
</para>
3242 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
3247 <term><varname>UseMTU=
</varname></term>
3249 <para>Takes a boolean. When true, the MTU received in the Router Advertisement will be
3250 used. Defaults to true.
</para>
3252 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3257 <term><varname>UseHopLimit=
</varname></term>
3259 <para>Takes a boolean. When true, the hop limit received in the Router Advertisement will be set to routes
3260 configured based on the advertisement. See also
<varname>IPv6HopLimit=
</varname>. Defaults to true.
</para>
3262 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3267 <term><varname>UseICMP6RateLimit=
</varname></term>
3269 <para>Takes a boolean. When true, the ICMP6 rate limit received in the Router Advertisement will be set to ICMP6
3270 rate limit based on the advertisement. Defaults to true.
</para>
3272 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3277 <term><varname>UseGateway=
</varname></term>
3279 <para>When true (the default), the router address will be configured as the default gateway.
3282 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3287 <term><varname>UseRoutePrefix=
</varname></term>
3289 <para>When true (the default), the routes corresponding to the route prefixes received in
3290 the Router Advertisement will be configured.
</para>
3292 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3297 <term><varname>UseCaptivePortal=
</varname></term>
3299 <para>When true (the default), the captive portal received in the Router Advertisement will be recorded
3300 and made available to client programs and displayed in the networkctl status output per-link.
</para>
3302 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
3307 <term><varname>UsePREF64=
</varname></term>
3309 <para>When true, the IPv6 PREF64 (or NAT64) prefixes received in the Router Advertisement will be recorded
3310 and made available to client programs and displayed in the
<command>networkctl
</command> status output per-link.
3311 See
<ulink url=
"https://tools.ietf.org/html/rfc8781">RFC
8781</ulink>. Defaults to false.
</para>
3313 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3318 <term><varname>UseAutonomousPrefix=
</varname></term>
3320 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
3321 precedence over any statically configured ones.
</para>
3323 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
3328 <term><varname>UseOnLinkPrefix=
</varname></term>
3330 <para>When true (the default), the onlink prefix received in the Router Advertisement will be
3331 used and takes precedence over any statically configured ones.
</para>
3333 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
3338 <term><varname>RouterDenyList=
</varname></term>
3340 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
3341 take a prefix length after
<literal>/
</literal>. Any information advertised by the listed
3342 router is ignored.
</para>
3344 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3349 <term><varname>RouterAllowList=
</varname></term>
3351 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
3352 take a prefix length after
<literal>/
</literal>. Only information advertised by the listed
3353 router is accepted. Note that if
<varname>RouterAllowList=
</varname> is configured then
3354 <varname>RouterDenyList=
</varname> is ignored.
</para>
3356 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3361 <term><varname>PrefixDenyList=
</varname></term>
3363 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
3364 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
3365 in the list are ignored.
</para>
3367 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3372 <term><varname>PrefixAllowList=
</varname></term>
3374 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
3375 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
3376 in the list are allowed. Note that if
<varname>PrefixAllowList=
</varname> is configured
3377 then
<varname>PrefixDenyList=
</varname> is ignored.
</para>
3379 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3384 <term><varname>RouteDenyList=
</varname></term>
3386 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
3387 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
3388 advertisements in the list are ignored.
</para>
3390 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3395 <term><varname>RouteAllowList=
</varname></term>
3397 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
3398 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
3399 advertisements in the list are allowed. Note that if
<varname>RouteAllowList=
</varname> is
3400 configured then
<varname>RouteDenyList=
</varname> is ignored.
</para>
3402 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3407 <term><varname>DHCPv6Client=
</varname></term>
3409 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true, the
3410 DHCPv6 client will be started in
<literal>solicit
</literal> mode if the RA has the
3411 <literal>managed
</literal> flag or
<literal>information-request
</literal> mode if the RA
3412 lacks the
<literal>managed
</literal> flag but has the
3413 <literal>other configuration
</literal> flag. If set to
<literal>always
</literal>, the
3414 DHCPv6 client will be started in
<literal>solicit
</literal> mode when an RA is received,
3415 even if neither the
<literal>managed
</literal> nor the
3416 <literal>other configuration
</literal> flag is set in the RA. This will be ignored when
3417 <varname>WithoutRA=
</varname> in the [DHCPv6] section is enabled, or
3418 <varname>UplinkInterface=:self
</varname> in the [DHCPPrefixDelegation] section is
3419 specified. Defaults to true.
</para>
3421 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3426 <term><varname>NetLabel=
</varname></term>
3428 <para>This applies the NetLabel for the addresses received with RA, like
3429 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
3430 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
3432 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
3437 <term><varname>NFTSet=
</varname></term>
3439 <para>This applies the NFT set for the network configuration received with RA, like
3440 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
3441 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
3442 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
3443 <literal>ipv6_addr
</literal>.
</para>
3445 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3452 <title>[DHCPServer] Section Options
</title>
3453 <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
3454 <varname>DHCPServer=
</varname> option described above:
</para>
3456 <variablelist class='network-directives'
>
3459 <term><varname>ServerAddress=
</varname></term>
3461 <para>Specifies the server address for the DHCP server. Takes an IPv4 address with prefix length
3462 separated with a slash, e.g.
<literal>192.168.0.1/
24</literal>. Defaults to unset, and one of
3463 static IPv4 addresses configured in [Network] or [Address] section will be automatically selected.
3464 This setting may be useful when the interface on which the DHCP server is running has multiple
3465 static IPv4 addresses.
</para>
3466 <para>This implies
<varname>Address=
</varname> in [Network] or [Address] section with the same
3467 address and prefix length. That is,
3468 <programlisting>[Network]
3470 Address=
192.168.0.1/
24
3471 Address=
192.168.0.2/
24
3473 ServerAddress=
192.168.0.1/
24</programlisting>
3475 <programlisting>[Network]
3478 Address=
192.168.0.1/
24
3480 Address=
192.168.0.2/
24
3482 ServerAddress=
192.168.0.1/
24</programlisting>
3483 are equivalent to the following.
3484 <programlisting>[Network]
3486 Address=
192.168.0.2/
24
3488 ServerAddress=
192.168.0.1/
24</programlisting>
3490 <para>Since version
255, like the
<varname>Address=
</varname> setting in [Network] or [Address]
3491 section, this also supports a null address, e.g.
<literal>0.0.0.0/
24</literal>, and an unused
3492 address will be automatically selected. For more details about the automatic address selection,
3493 see
<varname>Address=
</varname> setting in [Network] section in the above.
</para>
3495 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3500 <term><varname>PoolOffset=
</varname></term>
3501 <term><varname>PoolSize=
</varname></term>
3503 <listitem><para>Configures the pool of addresses to hand out. The pool
3504 is a contiguous sequence of IP addresses in the subnet configured for
3505 the server address, which does not include the subnet nor the broadcast
3506 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
3507 from the start of subnet, or zero to use the default value.
3508 <varname>PoolSize=
</varname> takes the number of IP addresses in the
3509 pool or zero to use the default value. By default, the pool starts at
3510 the first address after the subnet address and takes up the rest of
3511 the subnet, excluding the broadcast address. If the pool includes
3512 the server address (the default), this is reserved and not handed
3513 out to clients.
</para>
3515 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3519 <term><varname>DefaultLeaseTimeSec=
</varname></term>
3520 <term><varname>MaxLeaseTimeSec=
</varname></term>
3522 <listitem><para>Control the default and maximum DHCP lease
3523 time to pass to clients. These settings take time values in seconds or
3524 another common time unit, depending on the suffix. The default
3525 lease time is used for clients that did not ask for a specific
3526 lease time. If a client asks for a lease time longer than the
3527 maximum lease time, it is automatically shortened to the
3528 specified time. The default lease time defaults to
1h, the
3529 maximum lease time to
12h. Shorter lease times are beneficial
3530 if the configuration data in DHCP leases changes frequently
3531 and clients shall learn the new settings with shorter
3532 latencies. Longer lease times reduce the generated DHCP
3533 network traffic.
</para>
3535 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3539 <term><varname>UplinkInterface=
</varname></term>
3540 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
3541 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS, NTP, or SIP
3542 servers is enabled but no servers are specified, the servers configured in the uplink interface
3543 will be emitted. When
<literal>:auto
</literal>, the link which has a default gateway with the
3544 highest priority will be automatically selected. When
<literal>:none
</literal>, no uplink
3545 interface will be selected. Defaults to
<literal>:auto
</literal>.
</para>
3547 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3551 <term><varname>EmitDNS=
</varname></term>
3552 <term><varname>DNS=
</varname></term>
3554 <listitem><para><varname>EmitDNS=
</varname> takes a boolean. Configures whether the DHCP leases
3555 handed out to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
3556 The DNS servers to pass to clients may be configured with the
<varname>DNS=
</varname> option,
3557 which takes a list of IPv4 addresses, or special value
<literal>_server_address
</literal> which
3558 will be converted to the address used by the DHCP server.
</para>
3560 <para>If the
<varname>EmitDNS=
</varname> option is enabled but no servers configured, the
3561 servers are automatically propagated from an
"uplink" interface that has appropriate servers
3562 set. The
"uplink" interface is determined by the default route of the system with the highest
3563 priority. Note that this information is acquired at the time the lease is handed out, and does
3564 not take uplink interfaces into account that acquire DNS server information at a later point.
3565 If no suitable uplink interface is found the DNS server data from
3566 <filename>/etc/resolv.conf
</filename> is used. Also, note that the leases are not refreshed if
3567 the uplink network configuration changes. To ensure clients regularly acquire the most current
3568 uplink DNS server information, it is thus advisable to shorten the DHCP lease time via
3569 <varname>MaxLeaseTimeSec=
</varname> described above.
</para>
3571 <para>This setting can be specified multiple times. If an empty string is specified, then all
3572 DNS servers specified earlier are cleared.
</para>
3574 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3578 <term><varname>EmitNTP=
</varname></term>
3579 <term><varname>NTP=
</varname></term>
3580 <term><varname>EmitSIP=
</varname></term>
3581 <term><varname>SIP=
</varname></term>
3582 <term><varname>EmitPOP3=
</varname></term>
3583 <term><varname>POP3=
</varname></term>
3584 <term><varname>EmitSMTP=
</varname></term>
3585 <term><varname>SMTP=
</varname></term>
3586 <term><varname>EmitLPR=
</varname></term>
3587 <term><varname>LPR=
</varname></term>
3589 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname> settings
3590 described above, these settings configure whether and what server information for the indicate
3591 protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
3592 defaults apply as for
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname>.
</para>
3594 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3598 <term><varname>EmitRouter=
</varname></term>
3599 <term><varname>Router=
</varname></term>
3601 <listitem><para>The
<varname>EmitRouter=
</varname> setting takes a boolean value, and configures
3602 whether the DHCP lease should contain the router option. The
<varname>Router=
</varname> setting
3603 takes an IPv4 address, and configures the router address to be emitted. When the
3604 <varname>Router=
</varname> setting is not specified, then the server address will be used for
3605 the router option. When the
<varname>EmitRouter=
</varname> setting is disabled, the
3606 <varname>Router=
</varname> setting will be ignored. The
<varname>EmitRouter=
</varname> setting
3607 defaults to true, and the
<varname>Router=
</varname> setting defaults to unset.
3610 <xi:include href=
"version-info.xml" xpointer=
"v230"/></listitem>
3614 <term><varname>EmitTimezone=
</varname></term>
3615 <term><varname>Timezone=
</varname></term>
3617 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
3618 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
3619 <varname>Timezone=
</varname> setting takes a timezone string
3620 (such as
<literal>Europe/Berlin
</literal> or
3621 <literal>UTC
</literal>) to pass to clients. If no explicit
3622 timezone is set, the system timezone of the local host is
3623 propagated, as determined by the
3624 <filename>/etc/localtime
</filename> symlink.
</para>
3626 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3630 <term><varname>BootServerAddress=
</varname></term>
3633 <para>Takes an IPv4 address of the boot server used by e.g. PXE boot systems. When specified, this
3634 address is sent in the
<option>siaddr
</option> field of the DHCP message header. See
<ulink
3635 url=
"https://www.rfc-editor.org/rfc/rfc2131.html">RFC
2131</ulink> for more details. Defaults to
3638 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3643 <term><varname>BootServerName=
</varname></term>
3646 <para>Takes a name of the boot server used by e.g. PXE boot systems. When specified, this name is
3647 sent in the DHCP option
66 (
"TFTP server name"). See
<ulink
3648 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
3651 <para>Note that typically setting one of
<varname>BootServerName=
</varname> or
3652 <varname>BootServerAddress=
</varname> is sufficient, but both can be set too, if desired.
</para>
3654 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3659 <term><varname>BootFilename=
</varname></term>
3662 <para>Takes a path or URL to a file loaded by e.g. a PXE boot loader. When specified, this path is
3663 sent in the DHCP option
67 (
"Bootfile name"). See
<ulink
3664 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
3667 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3672 <term><varname>IPv6OnlyPreferredSec=
</varname></term>
3675 <para>Takes a timespan. Controls the
3676 <ulink url=
"https://tools.ietf.org/html/rfc8925">RFC
8925</ulink> IPv6-Only Preferred option.
3677 Specifies the DHCPv4 option to indicate that a host supports an IPv6-only mode and is willing to
3678 forgo obtaining an IPv4 address if the network provides IPv6 connectivity. Defaults to unset, and
3679 not send the option. The minimum allowed value is
300 seconds.
</para>
3681 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3686 <term><varname>SendOption=
</varname></term>
3688 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
3689 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
3690 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
3691 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
3692 <literal>string
</literal>. Special characters in the data string may be escaped using
3693 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
3694 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
3695 then all options specified earlier are cleared. Defaults to unset.
</para>
3697 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
3702 <term><varname>SendVendorOption=
</varname></term>
3704 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
3705 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
3706 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
3707 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
3708 <literal>string
</literal>. Special characters in the data string may be escaped using
3709 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
3710 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
3711 then all options specified earlier are cleared. Defaults to unset.
</para>
3713 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3717 <term><varname>BindToInterface=
</varname></term>
3719 <para>Takes a boolean value. When
<literal>yes
</literal>, DHCP server socket will be bound
3720 to its network interface and all socket communication will be restricted to this interface.
3721 Defaults to
<literal>yes
</literal>, except if
<varname>RelayTarget=
</varname> is used (see below),
3722 in which case it defaults to
<literal>no
</literal>.
</para>
3724 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3728 <term><varname>RelayTarget=
</varname></term>
3730 <para>Takes an IPv4 address, which must be in the format described in
3731 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
3732 Turns this DHCP server into a DHCP relay agent. See
<ulink url=
"https://tools.ietf.org/html/rfc1542">RFC
1542</ulink>.
3733 The address is the address of DHCP server or another relay agent to forward DHCP messages to and from.
</para>
3735 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3739 <term><varname>RelayAgentCircuitId=
</varname></term>
3741 <para>Specifies value for Agent Circuit ID suboption of Relay Agent Information option.
3742 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
3743 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
3744 Defaults to unset (means no Agent Circuit ID suboption is generated).
3745 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3747 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3751 <term><varname>RelayAgentRemoteId=
</varname></term>
3753 <para>Specifies value for Agent Remote ID suboption of Relay Agent Information option.
3754 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
3755 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
3756 Defaults to unset (means no Agent Remote ID suboption is generated).
3757 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3759 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3767 <title>[DHCPServerStaticLease] Section Options
</title>
3768 <para>The
<literal>[DHCPServerStaticLease]
</literal> section configures a static DHCP lease to assign a
3769 fixed IPv4 address to a specific device based on its MAC address. This section can be specified multiple
3772 <variablelist class='network-directives'
>
3774 <term><varname>MACAddress=
</varname></term>
3776 <listitem><para>The hardware address of a device to match. This key is mandatory.
</para>
3778 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3782 <term><varname>Address=
</varname></term>
3784 <listitem><para>The IPv4 address that should be assigned to the device that was matched with
3785 <varname>MACAddress=
</varname>. This key is mandatory.
</para>
3787 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3793 <title>[IPv6SendRA] Section Options
</title>
3794 <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
3795 to act as a router, if enabled via the
<varname>IPv6SendRA=
</varname> option described above. IPv6
3796 network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
3799 <variablelist class='network-directives'
>
3802 <term><varname>Managed=
</varname></term>
3803 <term><varname>OtherInformation=
</varname></term>
3805 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
3806 addresses on the network link when
<varname>Managed=
</varname>
3807 is set to
<literal>true
</literal> or if only additional network
3808 information can be obtained via DHCPv6 for the network link when
3809 <varname>OtherInformation=
</varname> is set to
3810 <literal>true
</literal>. Both settings default to
3811 <literal>false
</literal>, which means that a DHCPv6 server is not being
3814 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3818 <term><varname>RouterLifetimeSec=
</varname></term>
3820 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. The value must be
0
3821 seconds, or between
4 seconds and
9000 seconds. When set to
0, the host is not acting as a router.
3822 Defaults to
1800 seconds (
30 minutes).
</para>
3824 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
3829 <term><varname>RetransmitSec=
</varname></term>
3831 <listitem><para>Takes a timespan. Configures the retransmit time, used by clients to retransmit Neighbor
3832 Solicitation messages on address resolution and the Neighbor Unreachability Detection algorithm.
3833 An integer the default unit of seconds, in the range
0…
4294967295 msec. Defaults to
0.
</para>
3835 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3840 <term><varname>RouterPreference=
</varname></term>
3842 <listitem><para>Configures IPv6 router preference if
3843 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
3844 <literal>high
</literal>,
<literal>medium
</literal> and
3845 <literal>low
</literal>, with
<literal>normal
</literal> and
3846 <literal>default
</literal> added as synonyms for
3847 <literal>medium
</literal> just to make configuration easier. See
3848 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
3849 for details. Defaults to
<literal>medium
</literal>.
</para>
3851 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3855 <term><varname>HopLimit=
</varname></term>
3857 <para>Configures hop limit. Takes an integer in the range
0…
255. See also
3858 <varname>IPv6HopLimit=
</varname>.
</para>
3860 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3865 <term><varname>UplinkInterface=
</varname></term>
3866 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
3867 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS servers or
3868 search domains is enabled but no servers are specified, the servers configured in the uplink
3869 interface will be emitted. When
<literal>:auto
</literal>, the value specified to the same
3870 setting in the [DHCPPrefixDelegation] section will be used if
3871 <varname>DHCPPrefixDelegation=
</varname> is enabled, otherwise the link which has a default
3872 gateway with the highest priority will be automatically selected. When
<literal>:none
</literal>,
3873 no uplink interface will be selected. Defaults to
<literal>:auto
</literal>.
</para>
3875 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
3879 <term><varname>EmitDNS=
</varname></term>
3880 <term><varname>DNS=
</varname></term>
3882 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
3883 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is true.
3884 <varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that case
3885 the IPv6 link-local address is distributed. If
<varname>DNS=
</varname> is empty, DNS servers are
3886 read from the [Network] section. If the [Network] section does not contain any DNS servers
3887 either, DNS servers from the uplink interface specified in
<varname>UplinkInterface=
</varname>
3888 will be used. When
<varname>EmitDNS=
</varname> is false, no DNS server information is sent in
3889 Router Advertisement messages.
<varname>EmitDNS=
</varname> defaults to true.
</para>
3891 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3895 <term><varname>EmitDomains=
</varname></term>
3896 <term><varname>Domains=
</varname></term>
3898 <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
3899 <varname>EmitDomains=
</varname> is true. If
<varname>Domains=
</varname> is empty, DNS search
3900 domains are read from the [Network] section. If the [Network] section does not contain any DNS
3901 search domains either, DNS search domains from the uplink interface specified in
3902 <varname>UplinkInterface=
</varname> will be used. When
<varname>EmitDomains=
</varname> is false,
3903 no DNS search domain information is sent in Router Advertisement messages.
3904 <varname>EmitDomains=
</varname> defaults to true.
</para>
3906 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3910 <term><varname>DNSLifetimeSec=
</varname></term>
3912 <listitem><para>Lifetime in seconds for the DNS server addresses listed in
3913 <varname>DNS=
</varname> and search domains listed in
<varname>Domains=
</varname>. Defaults to
3914 3600 seconds (one hour).
</para>
3916 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3920 <term><varname>HomeAgent=
</varname></term>
3922 <listitem><para>Takes a boolean. Specifies that IPv6 router advertisements which indicates to hosts that
3923 the router acts as a Home Agent and includes a Home Agent Option. Defaults to false. See
3924 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink> for further details.
</para>
3926 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3931 <term><varname>HomeAgentLifetimeSec=
</varname></term>
3933 <listitem><para>Takes a timespan. Specifies the lifetime of the Home Agent. An integer the default unit of seconds,
3934 in the range
1…
65535. Defaults to the value set to
<varname>RouterLifetimeSec=
</varname>.
</para>
3936 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3941 <term><varname>HomeAgentPreference=
</varname></term>
3943 <listitem><para>Configures IPv6 Home Agent preference. Takes an integer in the range
0…
65535.
3944 Defaults to
0.
</para>
3946 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3954 <title>[IPv6Prefix] Section Options
</title>
3955 <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
3956 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink> for further
3959 <variablelist class='network-directives'
>
3962 <term><varname>AddressAutoconfiguration=
</varname></term>
3963 <term><varname>OnLink=
</varname></term>
3965 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
3966 autoconfigured with this prefix and whether the prefix can be used for
3967 onlink determination. Both settings default to
<literal>true
</literal>
3968 in order to ease configuration.
3971 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3975 <term><varname>Prefix=
</varname></term>
3977 <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
3978 IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
3979 <literal>/
</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
3980 prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
3981 prefix to another.
</para>
3983 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3987 <term><varname>PreferredLifetimeSec=
</varname></term>
3988 <term><varname>ValidLifetimeSec=
</varname></term>
3990 <listitem><para>Preferred and valid lifetimes for the prefix measured in seconds.
3991 <varname>PreferredLifetimeSec=
</varname> defaults to
1800 seconds (
30 minutes) and
3992 <varname>ValidLifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para>
3994 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3998 <term><varname>Assign=
</varname></term>
3999 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
4002 <xi:include href=
"version-info.xml" xpointer=
"v246"/></listitem>
4006 <term><varname>Token=
</varname></term>
4008 <para>Specifies an optional address generation mode for assigning an address in each
4009 prefix. This accepts the same syntax as
<varname>Token=
</varname> in the [IPv6AcceptRA]
4010 section. If
<varname>Assign=
</varname> is set to false, then this setting will be ignored.
4011 Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
4013 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4018 <term><varname>RouteMetric=
</varname></term>
4020 <para>The metric of the prefix route. Takes an unsigned integer in the range
0…
4294967295.
4021 When unset or set to
0, the kernel's default value is used. This setting is ignored when
4022 <varname>Assign=
</varname> is false.
</para>
4024 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
4031 <title>[IPv6RoutePrefix] Section Options
</title>
4032 <para>One or more [IPv6RoutePrefix] sections contain the IPv6
4033 prefix routes that are announced via Router Advertisements. See
4034 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
4035 for further details.
</para>
4037 <variablelist class='network-directives'
>
4040 <term><varname>Route=
</varname></term>
4042 <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
4043 IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
4044 separated by a
<literal>/
</literal> character. Use multiple [IPv6RoutePrefix] sections to configure
4045 multiple IPv6 prefix routes.
</para>
4047 <xi:include href=
"version-info.xml" xpointer=
"v244"/></listitem>
4051 <term><varname>LifetimeSec=
</varname></term>
4053 <listitem><para>Lifetime for the route prefix measured in seconds.
4054 <varname>LifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para>
4056 <xi:include href=
"version-info.xml" xpointer=
"v244"/></listitem>
4063 <title>[IPv6PREF64Prefix] Section Options
</title>
4064 <para>One or more [IPv6PREF64Prefix] sections contain the IPv6 PREF64 (or NAT64) prefixes that are announced via Router
4065 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc8781">RFC
8781</ulink> for further
4068 <variablelist class='network-directives'
>
4071 <term><varname>Prefix=
</varname></term>
4073 <listitem><para>The IPv6 PREF64 (or NAT64) prefix that is to be distributed to hosts. The setting holds
4074 an IPv6 prefix that should be set up for NAT64 translation (PLAT) to allow
464XLAT on the network segment.
4075 Use multiple [IPv6PREF64Prefix] sections to configure multiple IPv6 prefixes since prefix lifetime may differ
4076 from one prefix to another. The prefix is an address with a prefix length, separated by a slash
4077 <literal>/
</literal> character. Valid NAT64 prefix length are
96,
64,
56,
48,
40, and
32 bits.
</para>
4079 <xi:include href=
"version-info.xml" xpointer=
"v255"/></listitem></varlistentry>
4082 <term><varname>LifetimeSec=
</varname></term>
4083 <listitem><para>Lifetime for the prefix measured in seconds. Should be greater than or equal to
<varname>RouterLifetimeSec=
</varname>.
4084 <varname>LifetimeSec=
</varname> defaults to
1800 seconds.
</para>
4086 <xi:include href=
"version-info.xml" xpointer=
"v255"/></listitem>
4092 <title>[Bridge] Section Options
</title>
4093 <para>The [Bridge] section accepts the following keys:
</para>
4094 <variablelist class='network-directives'
>
4096 <term><varname>UnicastFlood=
</varname></term>
4098 <para>Takes a boolean. Controls whether the bridge should flood
4099 traffic for which an FDB entry is missing and the destination
4100 is unknown through this port. When unset, the kernel's default will be used.
4103 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4107 <term><varname>MulticastFlood=
</varname></term>
4109 <para>Takes a boolean. Controls whether the bridge should flood
4110 traffic for which an MDB entry is missing and the destination
4111 is unknown through this port. When unset, the kernel's default will be used.
4114 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4118 <term><varname>MulticastToUnicast=
</varname></term>
4120 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
4121 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
4122 When unset, the kernel's default will be used.
4125 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
4129 <term><varname>NeighborSuppression=
</varname></term>
4131 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
4132 this port. When unset, the kernel's default will be used.
4135 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4139 <term><varname>Learning=
</varname></term>
4141 <para>Takes a boolean. Configures whether MAC address learning is enabled for
4142 this port. When unset, the kernel's default will be used.
4145 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4149 <term><varname>HairPin=
</varname></term>
4151 <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
4152 was received. When this flag is false, then the bridge will not forward traffic back out of the
4153 receiving port. When unset, the kernel's default will be used.
</para>
4155 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4159 <term><varname>Isolated=
</varname></term>
4161 <para>Takes a boolean. Configures whether this port is isolated or not. Within a bridge,
4162 isolated ports can only communicate with non-isolated ports. When set to true, this port can only
4163 communicate with other ports whose Isolated setting is false. When set to false, this port
4164 can communicate with any other ports. When unset, the kernel's default will be used.
</para>
4166 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
4170 <term><varname>UseBPDU=
</varname></term>
4172 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
4173 processed by the bridge port. When unset, the kernel's default will be used.
</para>
4175 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4179 <term><varname>FastLeave=
</varname></term>
4181 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
4182 traffic on a port that receives an IGMP Leave message. It is only used with
4183 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
4185 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4189 <term><varname>AllowPortToBeRoot=
</varname></term>
4191 <para>Takes a boolean. Configures whether a given port is allowed to
4192 become a root port. Only used when STP is enabled on the bridge.
4193 When unset, the kernel's default will be used.
</para>
4195 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4199 <term><varname>ProxyARP=
</varname></term>
4201 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
4202 When unset, the kernel's default will be used.
</para>
4204 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4208 <term><varname>ProxyARPWiFi=
</varname></term>
4210 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
4211 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
4212 When unset, the kernel's default will be used.
</para>
4214 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4218 <term><varname>MulticastRouter=
</varname></term>
4220 <para>Configures this port for having multicast routers attached. A port with a multicast
4221 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
4222 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
4223 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
4224 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
4225 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
4227 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4231 <term><varname>Cost=
</varname></term>
4233 <para>Sets the
"cost" of sending packets of this interface.
4234 Each port in a bridge may have a different speed and the cost
4235 is used to decide which link to use. Faster interfaces
4236 should have lower costs. It is an integer value between
1 and
4239 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
4243 <term><varname>Priority=
</varname></term>
4245 <para>Sets the
"priority" of sending packets on this interface.
4246 Each port in a bridge may have a different priority which is used
4247 to decide which link to use. Lower value means higher priority.
4248 It is an integer value between
0 to
63. Networkd does not set any
4249 default, meaning the kernel default value of
32 is used.
</para>
4251 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
4257 <title>[BridgeFDB] Section Options
</title>
4258 <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
4259 keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.
</para>
4261 <variablelist class='network-directives'
>
4263 <term><varname>MACAddress=
</varname></term>
4265 <para>As in the [Network] section. This key is mandatory.
</para>
4267 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
4271 <term><varname>Destination=
</varname></term>
4273 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
4275 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4279 <term><varname>VLANId=
</varname></term>
4281 <para>The VLAN ID for the new static MAC table entry. If
4282 omitted, no VLAN ID information is appended to the new static MAC
4285 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
4289 <term><varname>VNI=
</varname></term>
4291 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
4292 the remote VXLAN tunnel endpoint. Takes a number in the range
1…
16777215.
4293 Defaults to unset.
</para>
4295 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4299 <term><varname>AssociatedWith=
</varname></term>
4301 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
4302 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
4303 <literal>use
</literal> means the address is in use. User space can use this option to
4304 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
4305 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
4306 means the address is associated with master devices fdb.
<literal>router
</literal> means
4307 the destination address is associated with a router. Note that it's valid if the referenced
4308 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
4310 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4314 <term><varname>OutgoingInterface=
</varname></term>
4316 <para>Specifies the name or index of the outgoing interface for the VXLAN device driver to
4317 reach the remote VXLAN tunnel endpoint. Defaults to unset.
</para>
4319 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
4325 <title>[BridgeMDB] Section Options
</title>
4326 <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
4327 keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.
</para>
4329 <variablelist class='network-directives'
>
4331 <term><varname>MulticastGroupAddress=
</varname></term>
4333 <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.
</para>
4335 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4339 <term><varname>VLANId=
</varname></term>
4341 <para>The VLAN ID for the new entry. Valid ranges are
0 (no VLAN) to
4094. Optional, defaults to
0.
</para>
4343 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4350 <title>[LLDP] Section Options
</title>
4351 <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
4353 <variablelist class='network-directives'
>
4355 <term><varname>MUDURL=
</varname></term>
4357 <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
4358 LLDP packets. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
4359 [DHCPv4] section described above.
</para>
4361 <para>The MUD URLs received via LLDP packets are saved and can be read using the
4362 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
4364 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4371 <title>[CAN] Section Options
</title>
4372 <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
4373 following keys:
</para>
4374 <variablelist class='network-directives'
>
4376 <term><varname>BitRate=
</varname></term>
4378 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
4379 be used here. Takes a number in the range
1…
4294967295.
</para>
4381 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4385 <term><varname>SamplePoint=
</varname></term>
4387 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
4388 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>). This will be ignored when
4389 <varname>BitRate=
</varname> is unspecified.
</para>
4391 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4395 <term><varname>TimeQuantaNSec=
</varname></term>
4396 <term><varname>PropagationSegment=
</varname></term>
4397 <term><varname>PhaseBufferSegment1=
</varname></term>
4398 <term><varname>PhaseBufferSegment2=
</varname></term>
4399 <term><varname>SyncJumpWidth=
</varname></term>
4401 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
4402 synchronization jump width, which allow one to define the CAN bit-timing in a hardware
4403 independent format as proposed by the Bosch CAN
2.0 Specification.
4404 <varname>TimeQuantaNSec=
</varname> takes a timespan in nanoseconds.
4405 <varname>PropagationSegment=
</varname>,
<varname>PhaseBufferSegment1=
</varname>,
4406 <varname>PhaseBufferSegment2=
</varname>, and
<varname>SyncJumpWidth=
</varname> take number
4407 of time quantum specified in
<varname>TimeQuantaNSec=
</varname> and must be an unsigned
4408 integer in the range
0…
4294967295. These settings except for
4409 <varname>SyncJumpWidth=
</varname> will be ignored when
<varname>BitRate=
</varname> is
4412 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4416 <term><varname>DataBitRate=
</varname></term>
4417 <term><varname>DataSamplePoint=
</varname></term>
4419 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
4420 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
4422 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4426 <term><varname>DataTimeQuantaNSec=
</varname></term>
4427 <term><varname>DataPropagationSegment=
</varname></term>
4428 <term><varname>DataPhaseBufferSegment1=
</varname></term>
4429 <term><varname>DataPhaseBufferSegment2=
</varname></term>
4430 <term><varname>DataSyncJumpWidth=
</varname></term>
4432 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
4433 synchronization jump width for the data phase, if CAN-FD is used. These settings are
4434 analogous to the
<varname>TimeQuantaNSec=
</varname> or related settings.
</para>
4436 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4440 <term><varname>FDMode=
</varname></term>
4442 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
4443 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
4444 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys, or
4445 <varname>DataTimeQuanta=
</varname> and related settings.
</para>
4447 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4451 <term><varname>FDNonISO=
</varname></term>
4453 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
4454 interface. When unset, the kernel's default will be used.
</para>
4456 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4460 <term><varname>RestartSec=
</varname></term>
4462 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
4463 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
4464 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
4465 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
4466 automatic restart off. By default automatic restart is disabled.
</para>
4468 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4472 <term><varname>Termination=
</varname></term>
4474 <para>Takes a boolean or a termination resistor value in ohm in the range
0…
65535. When
4475 <literal>yes
</literal>, the termination resistor is set to
120 ohm. When
4476 <literal>no
</literal> or
<literal>0</literal> is set, the termination resistor is disabled.
4477 When unset, the kernel's default will be used.
</para>
4479 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4483 <term><varname>TripleSampling=
</varname></term>
4485 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
4486 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
4488 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4492 <term><varname>BusErrorReporting=
</varname></term>
4494 <para>Takes a boolean. When
<literal>yes
</literal>, reporting of CAN bus errors is activated
4495 (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
4496 unable to send recessive bit, bus overload, active error announcement, error occurred on
4497 transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
4498 single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.
</para>
4500 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
4504 <term><varname>ListenOnly=
</varname></term>
4506 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
4507 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
4508 bit. Listen-only mode is important to debug CAN networks without interfering with the
4509 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
4512 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4516 <term><varname>Loopback=
</varname></term>
4518 <para>Takes a boolean. When
<literal>yes
</literal>, loopback mode is enabled. When the
4519 loopback mode is enabled, the interface treats messages transmitted by itself as received
4520 messages. The loopback mode is important to debug CAN networks. When unset, the kernel's
4521 default will be used.
</para>
4523 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4527 <term><varname>OneShot=
</varname></term>
4529 <para>Takes a boolean. When
<literal>yes
</literal>, one-shot mode is enabled. When unset,
4530 the kernel's default will be used.
</para>
4532 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4536 <term><varname>PresumeAck=
</varname></term>
4538 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will ignore missing CAN
4539 ACKs. When unset, the kernel's default will be used.
</para>
4541 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4545 <term><varname>ClassicDataLengthCode=
</varname></term>
4547 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will handle the
4bit data
4548 length code (DLC). When unset, the kernel's default will be used.
</para>
4550 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4557 <title>[IPoIB] Section Options
</title>
4558 <para>The [IPoIB] section manages the IP over Infiniband and accepts the following keys:
</para>
4559 <variablelist class='network-directives'
>
4560 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_mode" />
4561 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_umcast" />
4566 <title>[QDisc] Section Options
</title>
4567 <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).
</para>
4569 <variablelist class='network-directives'
>
4571 <term><varname>Parent=
</varname></term>
4573 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
4574 or
<literal>ingress
</literal>. This is mandatory.
</para>
4576 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
4580 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4585 <title>[NetworkEmulator] Section Options
</title>
4586 <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
4587 can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
4588 applications, or limit the bandwidth usage of a particular service to simulate internet connections.
4591 <variablelist class='network-directives'
>
4592 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4593 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4596 <term><varname>DelaySec=
</varname></term>
4598 <para>Specifies the fixed amount of delay to be added to all packets going out of the
4599 interface. Defaults to unset.
</para>
4601 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4606 <term><varname>DelayJitterSec=
</varname></term>
4608 <para>Specifies the chosen delay to be added to the packets outgoing to the network
4609 interface. Defaults to unset.
</para>
4611 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4616 <term><varname>PacketLimit=
</varname></term>
4618 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
4619 An unsigned integer in the range
0…
4294967294. Defaults to
1000.
</para>
4621 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4626 <term><varname>LossRate=
</varname></term>
4628 <para>Specifies an independent loss probability to be added to the packets outgoing from the
4629 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
4631 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4636 <term><varname>DuplicateRate=
</varname></term>
4638 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
4639 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
4641 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4648 <title>[TokenBucketFilter] Section Options
</title>
4649 <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
4652 <variablelist class='network-directives'
>
4653 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4654 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4657 <term><varname>LatencySec=
</varname></term>
4659 <para>Specifies the latency parameter, which specifies the maximum amount of time a
4660 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
4662 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4667 <term><varname>LimitBytes=
</varname></term>
4669 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
4670 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
4671 respectively, to the base of
1024. Defaults to unset.
</para>
4673 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4678 <term><varname>BurstBytes=
</varname></term>
4680 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
4681 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
4682 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to
4685 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4690 <term><varname>Rate=
</varname></term>
4692 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
4693 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
4694 Defaults to unset.
</para>
4696 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4701 <term><varname>MPUBytes=
</varname></term>
4703 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
4704 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
4705 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to zero.
</para>
4707 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4712 <term><varname>PeakRate=
</varname></term>
4714 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
4715 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
4716 1000. Defaults to unset.
</para>
4718 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4723 <term><varname>MTUBytes=
</varname></term>
4725 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
4726 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
4727 Defaults to unset.
</para>
4729 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4736 <title>[PIE] Section Options
</title>
4737 <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
4738 controller-Enhanced (PIE).
</para>
4740 <variablelist class='network-directives'
>
4741 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4742 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4745 <term><varname>PacketLimit=
</varname></term>
4747 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4748 incoming packets are dropped. An unsigned integer in the range
1…
4294967294. Defaults to unset and
4749 kernel's default is used.
</para>
4751 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4758 <title>[FlowQueuePIE] Section Options
</title>
4759 <para>The
<literal>[FlowQueuePIE]
</literal> section manages the queueing discipline
4760 (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).
</para>
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>PacketLimit=
</varname></term>
4769 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4770 incoming packets are dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and
4771 kernel's default is used.
</para>
4773 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4780 <title>[StochasticFairBlue] Section Options
</title>
4781 <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
4784 <variablelist class='network-directives'
>
4785 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4786 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4789 <term><varname>PacketLimit=
</varname></term>
4791 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4792 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
4793 kernel's default is used.
</para>
4795 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4802 <title>[StochasticFairnessQueueing] Section Options
</title>
4803 <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
4804 fairness queueing (sfq).
</para>
4806 <variablelist class='network-directives'
>
4807 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4808 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4811 <term><varname>PerturbPeriodSec=
</varname></term>
4813 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
4815 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4822 <title>[BFIFO] Section Options
</title>
4823 <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
4826 <variablelist class='network-directives'
>
4827 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4828 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4831 <term><varname>LimitBytes=
</varname></term>
4833 <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
4834 in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
4835 reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
4836 as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
4837 kernel default is used.
</para>
4839 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4846 <title>[PFIFO] Section Options
</title>
4847 <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
4850 <variablelist class='network-directives'
>
4851 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4852 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4855 <term><varname>PacketLimit=
</varname></term>
4857 <para>Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents
4858 overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this
4859 limit is reached, incoming packets are dropped. An unsigned integer in the range
4860 0…
4294967294. Defaults to unset and kernel's default is used.
</para>
4862 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4869 <title>[PFIFOHeadDrop] Section Options
</title>
4870 <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
4871 Head Drop (pfifo_head_drop).
</para>
4873 <variablelist class='network-directives'
>
4874 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4875 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4878 <term><varname>PacketLimit=
</varname></term>
4880 <para>As in [PFIFO] section.
</para>
4882 <xi:include href=
"version-info.xml" xpointer=
"v246"/></listitem>
4888 <title>[PFIFOFast] Section Options
</title>
4889 <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
4890 (pfifo_fast).
</para>
4892 <variablelist class='network-directives'
>
4893 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4894 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4899 <title>[CAKE] Section Options
</title>
4900 <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
4903 <variablelist class='network-directives'
>
4904 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4905 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4908 <term><varname>Bandwidth=
</varname></term>
4910 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
4911 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
4912 unset and kernel's default is used.
</para>
4914 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4919 <term><varname>AutoRateIngress=
</varname></term>
4921 <para>Takes a boolean value. Enables automatic capacity estimation based on traffic arriving
4922 at this qdisc. This is most likely to be useful with cellular links, which tend to change
4923 quality randomly. If this setting is enabled, the
<varname>Bandwidth=
</varname> setting is
4924 used as an initial estimate. Defaults to unset, and the kernel's default is used.
</para>
4926 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4931 <term><varname>OverheadBytes=
</varname></term>
4933 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative.
4934 Takes an integer in the range -
64…
256. Defaults to unset and kernel's default is used.
4937 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4942 <term><varname>MPUBytes=
</varname></term>
4944 <para>Rounds each packet (including overhead) up to the specified bytes. Takes an integer in
4945 the range
1…
256. Defaults to unset and kernel's default is used.
</para>
4947 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4952 <term><varname>CompensationMode=
</varname></term>
4954 <para>Takes one of
<literal>none
</literal>,
<literal>atm
</literal>, or
<literal>ptm
</literal>.
4955 Specifies the compensation mode for overhead calculation. When
<literal>none
</literal>, no
4956 compensation is taken into account. When
<literal>atm
</literal>, enables the compensation for
4957 ATM cell framing, which is normally found on ADSL links. When
<literal>ptm
</literal>, enables
4958 the compensation for PTM encoding, which is normally found on VDSL2 links and uses a
64b/
65b
4959 encoding scheme. Defaults to unset and the kernel's default is used.
</para>
4961 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4966 <term><varname>UseRawPacketSize=
</varname></term>
4968 <para>Takes a boolean value. When true, the packet size reported by the Linux kernel will be
4969 used, instead of the underlying IP packet size. Defaults to unset, and the kernel's default
4972 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4977 <term><varname>FlowIsolationMode=
</varname></term>
4979 <para>CAKE places packets from different flows into different queues, then packets from each
4980 queue are delivered fairly. This specifies whether the fairness is based on source address,
4981 destination address, individual flows, or any combination of those. The available values are:
4986 <term><option>none
</option></term>
4988 The flow isolation is disabled, and all traffic passes through a single queue.
4991 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
4994 <term><option>src-host
</option></term>
4996 Flows are defined only by source address. Equivalent to the
<literal>srchost
</literal>
4997 option for
<command>tc qdisc
</command> command. See also
4998 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5001 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5004 <term><option>dst-host
</option></term>
5006 Flows are defined only by destination address. Equivalent to the
5007 <literal>dsthost
</literal> option for
<command>tc qdisc
</command> command. See also
5008 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5011 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5014 <term><option>hosts
</option></term>
5016 Flows are defined by source-destination host pairs. Equivalent to the same option for
5017 <command>tc qdisc
</command> command. See also
5018 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5021 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5024 <term><option>flows
</option></term>
5026 Flows are defined by the entire
5-tuple of source address, destination address,
5027 transport protocol, source port and destination port. Equivalent to the same option for
5028 <command>tc qdisc
</command> command. See also
5029 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5032 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5035 <term><option>dual-src-host
</option></term>
5037 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
5038 fairness is applied first over source addresses, then over individual flows. Equivalent
5039 to the
<literal>dual-srchost
</literal> option for
<command>tc qdisc
</command> command.
5041 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5044 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5047 <term><option>dual-dst-host
</option></term>
5049 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
5050 fairness is applied first over destination addresses, then over individual flows.
5051 Equivalent to the
<literal>dual-dsthost
</literal> option for
5052 <command>tc qdisc
</command> command. See also
5053 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5056 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5059 <term><option>triple
</option></term>
5061 Flows are defined by the
5-tuple (see
<literal>flows
</literal>), and fairness is
5062 applied over source and destination addresses, and also over individual flows.
5063 Equivalent to the
<literal>triple-isolate
</literal> option for
5064 <command>tc qdisc
</command> command. See also
5065 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5068 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5072 <para>Defaults to unset and the kernel's default is used.
</para>
5074 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5079 <term><varname>NAT=
</varname></term>
5081 <para>Takes a boolean value. When true, CAKE performs a NAT lookup before applying
5082 flow-isolation rules, to determine the true addresses and port numbers of the packet, to
5083 improve fairness between hosts inside the NAT. This has no practical effect when
5084 <varname>FlowIsolationMode=
</varname> is
<literal>none
</literal> or
<literal>flows
</literal>,
5085 or if NAT is performed on a different host. Defaults to unset, and the kernel's default is
5088 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5093 <term><varname>PriorityQueueingPreset=
</varname></term>
5095 <para>CAKE divides traffic into
<literal>tins
</literal>, and each tin has its own independent
5096 set of flow-isolation queues, bandwidth threshold, and priority. This specifies the preset of
5097 tin profiles. The available values are:
</para>
5101 <term><option>besteffort
</option></term>
5103 Disables priority queueing by placing all traffic in one tin.
5106 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5109 <term><option>precedence
</option></term>
5111 Enables priority queueing based on the legacy interpretation of TOS
5112 <literal>Precedence
</literal> field. Use of this preset on the modern Internet is
5116 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5119 <term><option>diffserv8
</option></term>
5121 Enables priority queueing based on the Differentiated Service
5122 (
<literal>DiffServ
</literal>) field with eight tins: Background Traffic, High
5123 Throughput, Best Effort, Video Streaming, Low Latency Transactions, Interactive Shell,
5124 Minimum Latency, and Network Control.
5127 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5130 <term><option>diffserv4
</option></term>
5132 Enables priority queueing based on the Differentiated Service
5133 (
<literal>DiffServ
</literal>) field with four tins: Background Traffic, Best Effort,
5134 Streaming Media, and Latency Sensitive.
5137 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5140 <term><option>diffserv3
</option></term>
5142 Enables priority queueing based on the Differentiated Service
5143 (
<literal>DiffServ
</literal>) field with three tins: Background Traffic, Best Effort,
5144 and Latency Sensitive.
5147 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5151 <para>Defaults to unset, and the kernel's default is used.
</para>
5153 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5158 <term><varname>FirewallMark=
</varname></term>
5160 <para>Takes an integer in the range
1…
4294967295. When specified, firewall-mark-based
5161 overriding of CAKE's tin selection is enabled. Defaults to unset, and the kernel's default is
5164 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5169 <term><varname>Wash=
</varname></term>
5171 <para>Takes a boolean value. When true, CAKE clears the DSCP fields, except for ECN bits, of
5172 any packet passing through CAKE. Defaults to unset, and the kernel's default is used.
</para>
5174 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5179 <term><varname>SplitGSO=
</varname></term>
5181 <para>Takes a boolean value. When true, CAKE will split General Segmentation Offload (GSO)
5182 super-packets into their on-the-wire components and dequeue them individually. Defaults to
5183 unset, and the kernel's default is used.
</para>
5185 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5190 <term><varname>RTTSec=
</varname></term>
5192 <para>Specifies the RTT for the filter. Takes a timespan. Typical values are e.g.
100us for
5193 extremely high-performance
10GigE+ networks like datacentre,
1ms for non-WiFi LAN connections,
5194 100ms for typical internet connections. Defaults to unset, and the kernel's default will be used.
5197 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
5202 <term><varname>AckFilter=
</varname></term>
5204 <para>Takes a boolean value, or special value
<literal>aggressive
</literal>. If enabled, ACKs in
5205 each flow are queued and redundant ACKs to the upstream are dropped. If yes, the filter will always
5206 keep at least two redundant ACKs in the queue, while in
<literal>aggressive
</literal> mode, it will
5207 filter down to a single ACK. This may improve download throughput on links with very asymmetrical
5208 rate limits. Defaults to unset, and the kernel's default will be used.
</para>
5210 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
5218 <title>[ControlledDelay] Section Options
</title>
5219 <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
5220 controlled delay (CoDel).
</para>
5222 <variablelist class='network-directives'
>
5223 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5224 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5227 <term><varname>PacketLimit=
</varname></term>
5229 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
5230 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
5231 kernel's default is used.
</para>
5233 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5238 <term><varname>TargetSec=
</varname></term>
5240 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
5241 Defaults to unset and kernel's default is used.
</para>
5243 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5248 <term><varname>IntervalSec=
</varname></term>
5250 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
5251 become too stale. Defaults to unset and kernel's default is used.
</para>
5253 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5258 <term><varname>ECN=
</varname></term>
5260 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
5261 unset and kernel's default is used.
</para>
5263 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5268 <term><varname>CEThresholdSec=
</varname></term>
5270 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5271 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5273 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5280 <title>[DeficitRoundRobinScheduler] Section Options
</title>
5281 <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
5282 Robin Scheduler (DRR).
</para>
5284 <variablelist class='network-directives'
>
5285 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5286 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5291 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
5292 <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
5293 Robin Scheduler (DRR).
</para>
5295 <variablelist class='network-directives'
>
5296 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5297 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5300 <term><varname>QuantumBytes=
</varname></term>
5302 <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
5303 to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5304 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to the MTU of the
5307 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5315 <title>[EnhancedTransmissionSelection] Section Options
</title>
5316 <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
5317 Transmission Selection (ETS).
</para>
5319 <variablelist class='network-directives'
>
5320 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5321 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5324 <term><varname>Bands=
</varname></term>
5326 <para>Specifies the number of bands. An unsigned integer in the range
1…
16. This value has to be at
5327 least large enough to cover the strict bands specified through the
<varname>StrictBands=
</varname>
5328 and bandwidth-sharing bands specified in
<varname>QuantumBytes=
</varname>.
</para>
5330 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5335 <term><varname>StrictBands=
</varname></term>
5337 <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
5338 the range
1…
16.
</para>
5340 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5345 <term><varname>QuantumBytes=
</varname></term>
5347 <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
5348 suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5349 respectively, to the base of
1024. This setting can be specified multiple times. If an empty
5350 string is assigned, then the all previous assignments are cleared.
</para>
5352 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5357 <term><varname>PriorityMap=
</varname></term>
5359 <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
5360 separated list of numbers. The first number indicates which band the packets with priority
0 should
5361 be put to, the second is for priority
1, and so on. There can be up to
16 numbers in the list. If
5362 there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
5363 the last one. Each band number must be in the range
0…
255. This setting can be specified multiple
5364 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
5366 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5373 <title>[GenericRandomEarlyDetection] Section Options
</title>
5374 <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
5375 Early Detection (GRED).
</para>
5377 <variablelist class='network-directives'
>
5378 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5379 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5382 <term><varname>VirtualQueues=
</varname></term>
5384 <para>Specifies the number of virtual queues. Takes an integer in the range
1…
16. Defaults to unset
5385 and kernel's default is used.
</para>
5387 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5392 <term><varname>DefaultVirtualQueue=
</varname></term>
5394 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
5395 Defaults to unset and kernel's default is used.
</para>
5397 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5402 <term><varname>GenericRIO=
</varname></term>
5404 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
5405 unset and kernel's default is used.
</para>
5407 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5414 <title>[FairQueueingControlledDelay] Section Options
</title>
5415 <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
5416 controlled delay (FQ-CoDel).
</para>
5418 <variablelist class='network-directives'
>
5419 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5420 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5423 <term><varname>PacketLimit=
</varname></term>
5425 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
5426 dropped. Defaults to unset and kernel's default is used.
</para>
5428 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5433 <term><varname>MemoryLimitBytes=
</varname></term>
5435 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
5436 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5437 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
5439 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5444 <term><varname>Flows=
</varname></term>
5446 <para>Specifies the number of flows into which the incoming packets are classified.
5447 Defaults to unset and kernel's default is used.
</para>
5449 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5454 <term><varname>TargetSec=
</varname></term>
5456 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
5457 Defaults to unset and kernel's default is used.
</para>
5459 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5464 <term><varname>IntervalSec=
</varname></term>
5466 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
5467 become too stale. Defaults to unset and kernel's default is used.
</para>
5469 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5474 <term><varname>QuantumBytes=
</varname></term>
5476 <para>Specifies the number of bytes used as the
"deficit" in the fair queuing algorithm timespan.
5477 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5478 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
5480 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5485 <term><varname>ECN=
</varname></term>
5487 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
5488 unset and kernel's default is used.
</para>
5490 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5495 <term><varname>CEThresholdSec=
</varname></term>
5497 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5498 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5500 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5507 <title>[FairQueueing] Section Options
</title>
5508 <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
5511 <variablelist class='network-directives'
>
5512 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5513 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5516 <term><varname>PacketLimit=
</varname></term>
5518 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
5519 dropped. Defaults to unset and kernel's default is used.
</para>
5521 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5526 <term><varname>FlowLimit=
</varname></term>
5528 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
5529 unset and kernel's default is used.
</para>
5531 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5536 <term><varname>QuantumBytes=
</varname></term>
5538 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
5539 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5540 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
5541 default is used.
</para>
5543 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5548 <term><varname>InitialQuantumBytes=
</varname></term>
5550 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
5551 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
5552 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
5553 kernel's default is used.
</para>
5555 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5560 <term><varname>MaximumRate=
</varname></term>
5562 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
5563 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
5564 1000. Defaults to unset and kernel's default is used.
</para>
5566 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5571 <term><varname>Buckets=
</varname></term>
5573 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
5574 kernel's default is used.
</para>
5576 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5581 <term><varname>OrphanMask=
</varname></term>
5583 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
5584 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
5585 kernel's default is used.
</para>
5587 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5592 <term><varname>Pacing=
</varname></term>
5594 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
5595 default is used.
</para>
5597 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5602 <term><varname>CEThresholdSec=
</varname></term>
5604 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5605 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5607 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5614 <title>[TrivialLinkEqualizer] Section Options
</title>
5615 <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
5616 equalizer (teql).
</para>
5618 <variablelist class='network-directives'
>
5619 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5620 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5623 <term><varname>Id=
</varname></term>
5625 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
5626 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
5627 <constant>max_equalizers=N+
1</constant> option must be loaded before
5628 <command>systemd-networkd
</command> is started.
</para>
5630 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5637 <title>[HierarchyTokenBucket] Section Options
</title>
5638 <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
5639 bucket (htb).
</para>
5641 <variablelist class='network-directives'
>
5642 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5643 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5646 <term><varname>DefaultClass=
</varname></term>
5648 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
5649 to the class. Defaults to unset.
</para>
5651 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5656 <term><varname>RateToQuantum=
</varname></term>
5658 <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
5659 configured in
<varname>Rate=
</varname> by
<varname>RateToQuantum=
</varname>.
</para>
5661 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5668 <title>[HierarchyTokenBucketClass] Section Options
</title>
5669 <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
5672 <variablelist class='network-directives'
>
5673 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5674 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5677 <term><varname>Priority=
</varname></term>
5679 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
5680 priority field are tried for packets first.
</para>
5682 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5687 <term><varname>QuantumBytes=
</varname></term>
5689 <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
5690 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
5693 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5698 <term><varname>MTUBytes=
</varname></term>
5700 <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
5701 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
5703 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5708 <term><varname>OverheadBytes=
</varname></term>
5710 <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
5711 computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5712 Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
5714 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5719 <term><varname>Rate=
</varname></term>
5721 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
5722 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
5723 to the base of
1000. This setting is mandatory.
</para>
5725 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5730 <term><varname>CeilRate=
</varname></term>
5732 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
5733 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
5734 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
5737 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5742 <term><varname>BufferBytes=
</varname></term>
5744 <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
5745 with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
5746 to the base of
1024.
</para>
5748 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5753 <term><varname>CeilBufferBytes=
</varname></term>
5755 <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
5756 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5757 respectively, to the base of
1024.
</para>
5759 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5766 <title>[HeavyHitterFilter] Section Options
</title>
5767 <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
5770 <variablelist class='network-directives'
>
5771 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5772 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5775 <term><varname>PacketLimit=
</varname></term>
5777 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
5778 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
5779 kernel's default is used.
</para>
5781 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5788 <title>[QuickFairQueueing] Section Options
</title>
5789 <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
5792 <variablelist class='network-directives'
>
5793 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5794 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5799 <title>[QuickFairQueueingClass] Section Options
</title>
5800 <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
5803 <variablelist class='network-directives'
>
5804 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5805 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5808 <term><varname>Weight=
</varname></term>
5810 <para>Specifies the weight of the class. Takes an integer in the range
1…
1023. Defaults to
5811 unset in which case the kernel default is used.
</para>
5813 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5818 <term><varname>MaxPacketBytes=
</varname></term>
5820 <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the
5821 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
5822 1024. When unset, the kernel default is used.
</para>
5824 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5831 <title>[BridgeVLAN] Section Options
</title>
5832 <para>The [BridgeVLAN] section manages the VLAN ID configuration of a bridge port and accepts the
5833 following keys. Specify several [BridgeVLAN] sections to configure several VLAN entries. The
5834 <varname>VLANFiltering=
</varname> option has to be enabled, see the [Bridge] section in
5835 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
5837 <variablelist class='network-directives'
>
5839 <term><varname>VLAN=
</varname></term>
5841 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. Takes
5842 an integer in the range
1…
4094.
</para>
5844 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5848 <term><varname>EgressUntagged=
</varname></term>
5850 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
5851 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
5852 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
5854 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5858 <term><varname>PVID=
</varname></term>
5860 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
5861 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
5862 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
5864 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5871 <title>Examples
</title>
5873 <title>Static network configuration
</title>
5875 <programlisting># /etc/systemd/network/
50-static.network
5880 Address=
192.168.0.15/
24
5881 Gateway=
192.168.0.1</programlisting>
5883 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
5884 specified gateway will be used for a default route.
</para>
5888 <title>DHCP on ethernet links
</title>
5890 <programlisting># /etc/systemd/network/
80-dhcp.network
5895 DHCP=yes
</programlisting>
5897 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
5898 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
5902 <title>IPv6 Prefix Delegation (DHCPv6 PD)
</title>
5904 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-upstream.network
5911 # The below setting is optional, to also assign an address in the delegated prefix
5912 # to the upstream interface. If not necessary, then comment out the line below and
5913 # the [DHCPPrefixDelegation] section.
5914 DHCPPrefixDelegation=yes
5916 # If the upstream network provides Router Advertisement with Managed bit set,
5917 # then comment out the line below and WithoutRA= setting in the [DHCPv6] section.
5923 [DHCPPrefixDelegation]
5924 UplinkInterface=:self
5926 Announce=no
</programlisting>
5928 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-downstream.network
5933 DHCPPrefixDelegation=yes
5936 # It is expected that the host is acting as a router. So, usually it is not
5937 # necessary to receive Router Advertisement from other hosts in the downstream network.
5940 [DHCPPrefixDelegation]
5941 UplinkInterface=enp1s0
5943 Announce=yes
</programlisting>
5945 <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
5946 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
5947 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
5952 <title>IPv6 Prefix Delegation (DHCPv4
6RD)
</title>
5954 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-upstream.network
5961 # When DHCPv4-
6RD is used, the upstream network does not support IPv6.
5962 # Hence, it is not necessary to wait for Router Advertisement, which is enabled by default.
5966 Use6RD=yes
</programlisting>
5968 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-downstream.network
5973 DHCPPrefixDelegation=yes
5976 # It is expected that the host is acting as a router. So, usually it is not
5977 # necessary to receive Router Advertisement from other hosts in the downstream network.
5980 [DHCPPrefixDelegation]
5981 UplinkInterface=enp1s0
5983 Announce=yes
</programlisting>
5985 <para>This will enable DHCPv4-
6RD on the interface enp1s0 as an upstream interface where the
5986 DHCPv4 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
5987 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
5992 <title>A bridge with two enslaved links
</title>
5994 <programlisting># /etc/systemd/network/
25-bridge-static.netdev
5997 Kind=bridge
</programlisting>
5999 <programlisting># /etc/systemd/network/
25-bridge-static.network
6004 Address=
192.168.0.15/
24
6006 DNS=
192.168.0.1</programlisting>
6008 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
6013 Bridge=bridge0
</programlisting>
6015 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
6020 Bridge=bridge0
</programlisting>
6022 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
6023 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
6024 and network assigned, and a default route via the specified gateway will be
6025 added. The specified DNS server will be added to the global list of DNS resolvers.
6030 <title>Bridge port with VLAN forwarding
</title>
6033 # /etc/systemd/network/
25-bridge-slave-interface-
1.network
6049 EgressUntagged=
300-
400</programlisting>
6051 <para>This overrides the configuration specified in the previous example for the
6052 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
6053 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
6054 untagged when they leave on this interface. Untagged packets which arrive on this
6055 interface will be assigned VLAN ID
42.
</para>
6059 <title>Various tunnels
</title>
6061 <programlisting>/etc/systemd/network/
25-tunnels.network
6072 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
6078 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
6084 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
6090 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
6096 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
6097 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
6101 <title>A bond device
</title>
6103 <programlisting># /etc/systemd/network/
30-bond1.network
6111 <programlisting># /etc/systemd/network/
30-bond1.netdev
6117 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
6119 MACAddress=
52:
54:
00:e9:
64:
41
6125 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
6127 MACAddress=
52:
54:
00:e9:
64:
42
6133 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
6134 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
6135 will be used to acquire an address.
</para>
6139 <title>Virtual Routing and Forwarding (VRF)
</title>
6140 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
6141 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
6142 within the routing table defined during VRF creation. For kernels before
4.8 traffic
6143 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
6145 <programlisting># /etc/systemd/network/
25-vrf.network
6155 <title>MacVTap
</title>
6156 <para>This brings up a network interface
<literal>macvtap-test
</literal>
6157 and attaches it to
<literal>enp0s25
</literal>.
</para>
6158 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
6163 MACVTAP=macvtap-test
6168 <title>A Xfrm interface with physical underlying device.
</title>
6170 <programlisting># /etc/systemd/network/
27-xfrm.netdev
6176 InterfaceId=
7</programlisting>
6178 <programlisting># /etc/systemd/network/
27-eth0.network
6183 Xfrm=xfrm0
</programlisting>
6185 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
6186 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
6187 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
6193 <title>See Also
</title>
6195 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
6196 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
6197 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
6198 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
6199 <citerefentry><refentrytitle>systemd-network-generator.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
6200 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>