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>DHCPPrefixDelegation=
</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.
1719 This is mandatory if
<varname>ManageForeignNextHops=no
</varname> is specified in
1720 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1721 Otherwise, if unspecified, an unused ID will be automatically picked.
</para>
1723 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
1728 <term><varname>Gateway=
</varname></term>
1730 <para>As in the [Network] section.
</para>
1732 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
1737 <term><varname>Family=
</varname></term>
1739 <para>Takes one of the special values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>.
1740 By default, the family is determined by the address specified in
1741 <varname>Gateway=
</varname>. If
<varname>Gateway=
</varname> is not specified, then defaults
1742 to
<literal>ipv4
</literal>.
</para>
1744 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1749 <term><varname>OnLink=
</varname></term>
1751 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1752 reachable directly by the current machine (i.e., attached to the local network), so that we
1753 can insert the nexthop in the kernel table without it being complained about. Defaults to
1754 <literal>no
</literal>.
</para>
1756 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1761 <term><varname>Blackhole=
</varname></term>
1763 <para>Takes a boolean. If enabled, packets to the corresponding routes are discarded
1764 silently, and
<varname>Gateway=
</varname> cannot be specified. Defaults to
1765 <literal>no
</literal>.
</para>
1767 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1772 <term><varname>Group=
</varname></term>
1774 <para>Takes a whitespace separated list of nexthop IDs. Each ID must be in the range
1775 1…
4294967295. Optionally, each nexthop ID can take a weight after a colon
1776 (
<literal><replaceable>id
</replaceable><optional>:
<replaceable>weight
</replaceable></optional></literal>).
1777 The weight must be in the range
1…
255. If the weight is not specified, then it is assumed
1778 that the weight is
1. This setting cannot be specified with
<varname>Gateway=
</varname>,
1779 <varname>Family=
</varname>,
<varname>Blackhole=
</varname>. This setting can be specified
1780 multiple times. If an empty string is assigned, then the all previous assignments are
1781 cleared. Defaults to unset.
</para>
1783 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
1790 <title>[Route] Section Options
</title>
1792 <para>The [Route] section accepts the following settings. Specify several [Route] sections to
1793 configure several routes.
</para>
1795 <variablelist class='network-directives'
>
1797 <term><varname>Gateway=
</varname></term>
1799 <para>Takes the gateway address or the special values
<literal>_dhcp4
</literal> and
1800 <literal>_ipv6ra
</literal>. If
<literal>_dhcp4
</literal> or
<literal>_ipv6ra
</literal> is
1801 set, then the gateway address provided by DHCPv4 or IPv6 RA is used.
</para>
1803 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1808 <term><varname>GatewayOnLink=
</varname></term>
1810 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1811 reachable directly by the current machine (i.e., attached to the local network), so that we
1812 can insert the route in the kernel table without it being complained about. Defaults to
1813 <literal>no
</literal>.
</para>
1815 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1820 <term><varname>Destination=
</varname></term>
1822 <para>The destination prefix of the route. Possibly followed by a slash and the prefix
1823 length. If omitted, a full-length host route is assumed.
</para>
1825 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1830 <term><varname>Source=
</varname></term>
1832 <para>The source prefix of the route. Possibly followed by a slash and the prefix length. If
1833 omitted, a full-length host route is assumed.
</para>
1835 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
1840 <term><varname>Metric=
</varname></term>
1842 <para>The metric of the route. Takes an unsigned integer in the range
0…
4294967295. Defaults
1843 to unset, and the kernel's default will be used.
</para>
1845 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
1850 <term><varname>IPv6Preference=
</varname></term>
1852 <para>Specifies the route preference as defined in
1853 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink> for Router Discovery
1854 messages. Which can be one of
<literal>low
</literal> the route has a lowest priority,
1855 <literal>medium
</literal> the route has a default priority or
<literal>high
</literal> the
1856 route has a highest priority.
</para>
1858 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1863 <term><varname>Scope=
</varname></term>
1865 <para>The scope of the IPv4 route, which can be
<literal>global
</literal>,
1866 <literal>site
</literal>,
<literal>link
</literal>,
<literal>host
</literal>, or
1867 <literal>nowhere
</literal>:
</para>
1870 <para><literal>global
</literal> means the route can reach hosts more than one hop away.
1875 <para><literal>site
</literal> means an interior route in the local autonomous system.
1880 <para><literal>link
</literal> means the route can only reach hosts on the local network
1881 (one hop away).
</para>
1885 <para><literal>host
</literal> means the route will not leave the local machine (used for
1886 internal addresses like
127.0.0.1).
</para>
1890 <para><literal>nowhere
</literal> means the destination doesn't exist.
</para>
1894 <para>For IPv4 route, defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
1895 <literal>local
</literal> or
<literal>nat
</literal>, and
<literal>link
</literal> if
1896 <varname>Type=
</varname> is
<literal>broadcast
</literal>,
<literal>multicast
</literal>,
1897 <literal>anycast
</literal>, or
<literal>unicast
</literal>. In other cases,
1898 defaults to
<literal>global
</literal>. The value is not used for IPv6.
</para>
1900 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
1905 <term><varname>PreferredSource=
</varname></term>
1907 <para>The preferred source address of the route. The address must be in the format described
1909 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1912 <xi:include href=
"version-info.xml" xpointer=
"v227"/>
1917 <term><varname>Table=
</varname></term>
1919 <para>The table identifier for the route. Takes one of predefined names
1920 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
1921 defined in
<varname>RouteTable=
</varname> in
1922 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1923 or a number between
1 and
4294967295. The table can be retrieved using
1924 <command>ip route show table
<replaceable>num
</replaceable></command>. If unset and
1925 <varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1926 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1927 In other cases, defaults to
<literal>main
</literal>.
</para>
1929 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
1934 <term><varname>HopLimit=
</varname></term>
1936 <para>Configures per route hop limit. Takes an integer in the range
1…
255. See also
1937 <varname>IPv6HopLimit=
</varname>.
</para>
1939 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
1944 <term><varname>Protocol=
</varname></term>
1946 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special
1947 values
<literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1948 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1951 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1956 <term><varname>Type=
</varname></term>
1958 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1959 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1960 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1961 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1962 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e.
1963 a route indicating the path to take to a destination network address. If
1964 <literal>blackhole
</literal>, packets to the defined route are discarded silently. If
1965 <literal>unreachable
</literal>, packets to the defined route are discarded and the ICMP
1966 message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets to the
1967 defined route are discarded and the ICMP message
"Communication Administratively Prohibited"
1968 is generated. If
<literal>throw
</literal>, route lookup in the current routing table will
1969 fail and the route selection process will return to Routing Policy Database (RPDB). Defaults
1970 to
<literal>unicast
</literal>.
</para>
1972 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1977 <term><varname>InitialCongestionWindow=
</varname></term>
1979 <para>The TCP initial congestion window is used during the start of a TCP connection.
1980 During the start of a TCP session, when a client requests a resource, the server's initial
1981 congestion window determines how many packets will be sent during the initial burst of data
1982 without waiting for acknowledgement. Takes a number between
1 and
1023. Note that
100 is
1983 considered an extremely large value for this option. When unset, the kernel's default
1984 (typically
10) will be used.
</para>
1986 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
1991 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1993 <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
1994 that can initially be buffered at one time on a connection. The sending host can send only
1995 that amount of data before waiting for an acknowledgment and window update from the
1996 receiving host. Takes a number between
1 and
1023. Note that
100 is considered an extremely
1997 large value for this option. When unset, the kernel's default will be used.
</para>
1999 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
2004 <term><varname>QuickAck=
</varname></term>
2006 <para>Takes a boolean. When true, the TCP quick ACK mode for the route is enabled. When unset,
2007 the kernel's default will be used.
</para>
2009 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
2014 <term><varname>FastOpenNoCookie=
</varname></term>
2016 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
2017 When unset, the kernel's default will be used.
</para>
2019 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2024 <term><varname>TTLPropagate=
</varname></term>
2026 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
2027 When unset, the kernel's default will be used.
</para>
2029 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2034 <term><varname>MTUBytes=
</varname></term>
2036 <para>The maximum transmission unit in bytes to set for the route. The usual suffixes K, M,
2037 G, are supported and are understood to the base of
1024.
</para>
2039 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
2044 <term><varname>TCPAdvertisedMaximumSegmentSize=
</varname></term>
2046 <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G,
2047 are supported and are understood to the base of
1024. An unsigned integer in the range
2048 1…
4294967294. When unset, the kernel's default will be used.
</para>
2050 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2055 <term><varname>TCPCongestionControlAlgorithm=
</varname></term>
2057 <para>Specifies the TCP congestion control algorithm for the route. Takes a name of the algorithm,
2058 e.g.
<literal>bbr
</literal>,
<literal>dctcp
</literal>, or
<literal>vegas
</literal>. When unset,
2059 the kernel's default will be used.
</para>
2061 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2066 <term><varname>TCPRetransmissionTimeoutSec=
</varname></term>
2068 <para>Specifies the TCP Retransmission Timeout (RTO) for the route. Takes time values in seconds.
2069 This value specifies the timeout of an alive TCP connection, when retransmissions remain
2070 unacknowledged. When unset, the kernel's default will be used.
</para>
2072 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2077 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
2079 <para>Configures multipath route. Multipath routing is the technique of using multiple
2080 alternative paths through a network. Takes gateway address. Optionally, takes a network
2081 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for this
2082 multipath route separated with whitespace. This setting can be specified multiple times. If
2083 an empty string is assigned, then the all previous assignments are cleared.
</para>
2085 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2090 <term><varname>NextHop=
</varname></term>
2092 <para>Specifies the nexthop id. Takes an unsigned integer in the range
1…
4294967295. If set,
2093 the corresponding [NextHop] section must be configured. Defaults to unset.
</para>
2095 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2102 <title>[DHCPv4] Section Options
</title>
2104 <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
2105 <varname>DHCP=
</varname> setting described above:
</para>
2107 <variablelist class='network-directives'
>
2109 <!-- DHCP packet contents -->
2112 <term><varname>RequestAddress=
</varname></term>
2114 <para>Takes an IPv4 address. When specified, the Requested IP Address option (option code
50) is
2115 added with it to the initial DHCPDISCOVER message sent by the DHCP client. Defaults to unset, and
2116 an already assigned dynamic address to the interface is automatically picked.
</para>
2118 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2123 <term><varname>SendHostname=
</varname></term>
2125 <para>When true (the default), the machine's hostname (or the value specified with
2126 <varname>Hostname=
</varname>, described below) will be sent to the DHCP server. Note that the
2127 hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and be
2128 formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option
2131 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
2136 <term><varname>Hostname=
</varname></term>
2138 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's
2139 hostname. Note that the specified hostname must consist only of
7-bit ASCII lower-case
2140 characters and no spaces or dots, and be formatted as a valid DNS domain name.
</para>
2142 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
2147 <term><varname>MUDURL=
</varname></term>
2149 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent
2150 to the DHCPv4 server. Takes a URL of length up to
255 characters. A superficial verification
2151 that the string is a valid URL will be performed. DHCPv4 clients are intended to have at most
2152 one MUD URL associated with them. See
2153 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
2155 <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers
2156 to advertise device specifications, including the intended communication patterns for their
2157 device when it connects to the network. The network can then use this to author a
2158 context-specific access policy, so the device functions only within those parameters.
</para>
2160 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2165 <term><varname>ClientIdentifier=
</varname></term>
2167 <para>The DHCPv4 client identifier to use. Takes one of
<option>mac
</option> or
2168 <option>duid
</option>. If set to
<option>mac
</option>, the MAC address of the link is used. If set
2169 to
<option>duid
</option>, an RFC4361-compliant Client ID, which is the combination of IAID and
2170 DUID, is used. IAID can be configured by
<varname>IAID=
</varname>. DUID can be configured by
2171 <varname>DUIDType=
</varname> and
<varname>DUIDRawData=
</varname>. Defaults to
2172 <option>duid
</option>.
</para>
2174 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
2179 <term><varname>VendorClassIdentifier=
</varname></term>
2181 <para>The vendor class identifier used to identify vendor type and configuration.
</para>
2183 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2188 <term><varname>UserClass=
</varname></term>
2190 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or
2191 applications it represents. The information contained in this option is a string that
2192 represents the user class of which the client is a member. Each class sets an identifying
2193 string of information to be used by the DHCP service to classify clients. Takes a
2194 whitespace-separated list of strings.
</para>
2196 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
2201 <term><varname>DUIDType=
</varname></term>
2203 <para>Override the global
<varname>DUIDType=
</varname> setting for this network. See
2204 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2205 for a description of possible values.
</para>
2207 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2212 <term><varname>DUIDRawData=
</varname></term>
2214 <para>Override the global
<varname>DUIDRawData=
</varname> setting for this network. See
2215 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2216 for a description of possible values.
</para>
2218 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2223 <term><varname>IAID=
</varname></term>
2225 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned
2228 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2233 <term><varname>RapidCommit=
</varname></term>
2235 <para>Takes a boolean. The DHCPv4 client can obtain configuration parameters from a DHCPv4 server
2236 through a rapid two-message exchange (discover and ack). When the rapid commit option is set by
2237 both the DHCPv4 client and the DHCPv4 server, the two-message exchange is used. Otherwise, the
2238 four-message exchange (discover, offer, request, and ack) is used. The two-message exchange
2239 provides faster client configuration. See
2240 <ulink url=
"https://tools.ietf.org/html/rfc4039">RFC
4039</ulink> for details.
2241 Defaults to true when
<varname>Anonymize=no
</varname> and neither
<varname>AllowList=
</varname>
2242 nor
<varname>DenyList=
</varname> is specified, and false otherwise.
</para>
2244 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2249 <term><varname>Anonymize=
</varname></term>
2251 <para>Takes a boolean. When true, the options sent to the DHCP server will follow the
2252 <ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink> (Anonymity Profiles for
2253 DHCP Clients) to minimize disclosure of identifying information. Defaults to false.
</para>
2255 <para>This option should only be set to true when
<varname>MACAddressPolicy=
</varname> is set
2256 to
<option>random
</option> (see
2257 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
2261 <varname>ClientIdentifier=mac
</varname>,
2262 <varname>RapidCommit=no
</varname>,
2263 <varname>SendHostname=no
</varname>,
2264 <varname>Use6RD=no
</varname>,
2265 <varname>UseCaptivePortal=no
</varname>,
2266 <varname>UseMTU=no
</varname>,
2267 <varname>UseNTP=no
</varname>,
2268 <varname>UseSIP=no
</varname>, and
2269 <varname>UseTimezone=no
</varname>
2270 are implied and these settings in the .network file are silently ignored. Also,
2271 <varname>Hostname=
</varname>,
2272 <varname>MUDURL=
</varname>,
2273 <varname>RequestAddress
</varname>,
2274 <varname>RequestOptions=
</varname>,
2275 <varname>SendOption=
</varname>,
2276 <varname>SendVendorOption=
</varname>,
2277 <varname>UserClass=
</varname>, and
2278 <varname>VendorClassIdentifier=
</varname>
2279 are silently ignored.
</para>
2281 <para>With this option enabled DHCP requests will mimic those generated by Microsoft
2282 Windows, in order to reduce the ability to fingerprint and recognize installations. This
2283 means DHCP request sizes will grow and lease data will be more comprehensive than normally,
2284 though most of the requested data is not actually used.
</para>
2286 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
2291 <term><varname>RequestOptions=
</varname></term>
2293 <para>Sets request options to be sent to the server in the DHCPv4 request options list. A
2294 whitespace-separated list of integers in the range
1…
254. Defaults to unset.
</para>
2296 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2301 <term><varname>SendOption=
</varname></term>
2303 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data
2304 type and data separated with a colon
2305 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2306 The option number must be an integer in the range
1…
254. The type takes one of
2307 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
2308 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
2309 string may be escaped using
2310 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2311 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2312 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
2314 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2319 <term><varname>SendVendorOption=
</varname></term>
2321 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data
2322 type and data separated with a colon
2323 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2324 The option number must be an integer in the range
1…
254. The type takes one of
2325 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
2326 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
2327 string may be escaped using
2328 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2329 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2330 then all options specified earlier are cleared. Defaults to unset.
</para>
2332 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2337 <term><varname>IPServiceType=
</varname></term>
2339 <para>Takes one of the special values
<literal>none
</literal>,
<literal>CS6
</literal>, or
2340 <literal>CS4
</literal>. When
<literal>none
</literal> no IP service type is set to the packet
2341 sent from the DHCPv4 client. When
<literal>CS6
</literal> (network control) or
2342 <literal>CS4
</literal> (realtime), the corresponding service type will be set. Defaults to
2343 <literal>CS6
</literal>.
</para>
2345 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2350 <term><varname>SocketPriority=
</varname></term>
2352 <para>The Linux socket option
<constant>SO_PRIORITY
</constant> applied to the raw IP socket used for
2353 initial DHCPv4 messages. Unset by default. Usual values range from
0 to
6.
2354 More details about
<constant>SO_PRIORITY
</constant> socket option in
2355 <citerefentry project='man-pages'
><refentrytitle>socket
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
2356 Can be used in conjunction with [VLAN] section
<varname>EgressQOSMaps=
</varname> setting of .netdev
2357 file to set the
802.1Q VLAN ethernet tagged header priority, see
2358 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2361 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
2365 <!-- How to use the DHCP lease -->
2368 <term><varname>Label=
</varname></term>
2370 <para>Specifies the label for the IPv4 address received from the DHCP server. The label must
2371 be a
7-bit ASCII string with a length of
1…
15 characters. Defaults to unset.
</para>
2373 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2378 <term><varname>UseDNS=
</varname></term>
2380 <para>When true (the default), the DNS servers received from the DHCP server will be used.
2383 <para>This corresponds to the
<option>nameserver
</option> option in
2384 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2387 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2392 <term><varname>RoutesToDNS=
</varname></term>
2394 <para>When true, the routes to the DNS servers received from the DHCP server will be
2395 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored. Defaults to
2398 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2403 <term><varname>UseNTP=
</varname></term>
2405 <para>When true (the default), the NTP servers received from the DHCP server will be used by
2406 <filename>systemd-timesyncd.service
</filename>.
</para>
2408 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
2413 <term><varname>RoutesToNTP=
</varname></term>
2415 <para>When true, the routes to the NTP servers received from the DHCP server will be
2416 configured. When
<varname>UseNTP=
</varname> is disabled, this setting is ignored. Defaults to
2419 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
2424 <term><varname>UseSIP=
</varname></term>
2426 <para>When true (the default), the SIP servers received from the DHCP server will be collected
2427 and made available to client programs.
</para>
2429 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2434 <term><varname>UseCaptivePortal=
</varname></term>
2436 <para>When true (the default), the captive portal advertised by the DHCP server will be recorded
2437 and made available to client programs and displayed in the
2438 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
2439 status output per-link.
</para>
2441 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
2446 <term><varname>UseMTU=
</varname></term>
2448 <para>When true, the interface maximum transmission unit from the DHCP server will be used on
2449 the current link. If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
2450 Defaults to false.
</para>
2452 <para>Note, some drivers will reset the interfaces if the MTU is changed. For such
2453 interfaces, please try to use
<varname>IgnoreCarrierLoss=
</varname> with a short timespan,
2454 e.g.
<literal>3 seconds
</literal>.
</para>
2456 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2461 <term><varname>UseHostname=
</varname></term>
2463 <para>When true (the default), the hostname received from the DHCP server will be set as the
2464 transient hostname of the system.
</para>
2466 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2471 <term><varname>UseDomains=
</varname></term>
2473 <para>Takes a boolean, or the special value
<option>route
</option>. When true, the domain name
2474 received from the DHCP server will be used as DNS search domain over this link, similarly to the
2475 effect of the
<option>Domains=
</option> setting. If set to
<option>route
</option>, the domain name
2476 received from the DHCP server will be used for routing DNS queries only, but not for searching,
2477 similarly to the effect of the
<option>Domains=
</option> setting when the argument is prefixed with
2478 <literal>~
</literal>. Defaults to false.
</para>
2480 <para>It is recommended to enable this option only on trusted networks, as setting this
2481 affects resolution of all hostnames, in particular of single-label names. It is generally
2482 safer to use the supplied domain only as routing domain, rather than as search domain, in
2483 order to not have it affect local resolution of single-label names.
</para>
2485 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
2486 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2489 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2494 <term><varname>UseRoutes=
</varname></term>
2496 <para>When true (the default), the static routes will be requested from the DHCP server and
2497 added to the routing table with a metric of
1024, and a scope of
<option>global
</option>,
2498 <option>link
</option> or
<option>host
</option>, depending on the route's destination and
2499 gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the link's
2500 own address, the scope will be set to
<option>host
</option>. Otherwise if the gateway is null
2501 (a direct route), a
<option>link
</option> scope will be used. For anything else, scope
2502 defaults to
<option>global
</option>.
</para>
2504 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
2509 <term><varname>RouteMetric=
</varname></term>
2511 <para>Set the routing metric for routes specified by the DHCP server (including the prefix
2512 route added for the specified prefix). Takes an unsigned integer in the range
0…
4294967295.
2513 Defaults to
1024.
</para>
2515 <xi:include href=
"version-info.xml" xpointer=
"v217"/>
2520 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
2522 <para>The table identifier for DHCP routes. Takes one of predefined names
2523 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
2524 defined in
<varname>RouteTable=
</varname> in
2525 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2526 or a number between
1…
4294967295.
</para>
2528 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
2529 used when this parameter is not specified.
</para>
2531 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
2536 <term><varname>RouteMTUBytes=
</varname></term>
2538 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further
2541 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2546 <term><varname>QuickAck=
</varname></term>
2548 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
2549 the acquired DHCPv4 lease. When unset, the kernel's default will be used.
</para>
2551 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
2556 <term><varname>InitialCongestionWindow=
</varname></term>
2558 <para>As in the [Route] section.
</para>
2560 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2565 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
2567 <para>As in the [Route] section.
</para>
2569 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2574 <term><varname>UseGateway=
</varname></term>
2576 <para>When true, and the DHCP server provides a Router option, the default gateway based on the
2577 router address will be configured. Defaults to unset, and the value specified with
2578 <varname>UseRoutes=
</varname> will be used.
</para>
2580 <para>Note, when the server provides both the Router and Classless Static Routes option, and
2581 <varname>UseRoutes=
</varname> is enabled, the Router option is always ignored regardless of this
2582 setting. See
<ulink url=
"https://datatracker.ietf.org/doc/html/rfc3442">RFC
3442</ulink>.
</para>
2584 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2589 <term><varname>UseTimezone=
</varname></term>
2590 <listitem><para>When true, the timezone received from the DHCP server will be set as timezone
2591 of the local system. Defaults to false.
</para>
2593 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
2597 <term><varname>Use6RD=
</varname></term>
2599 <para>When true, subnets of the received IPv6 prefix are assigned to downstream interfaces
2600 which enables
<varname>DHCPPrefixDelegation=
</varname>. See also
2601 <varname>DHCPPrefixDelegation=
</varname> in the [Network] section, the [DHCPPrefixDelegation]
2602 section, and
<ulink url=
"https://tools.ietf.org/html/rfc5969">RFC
5969</ulink>. Defaults to
2605 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2610 <term><varname>IPv6OnlyMode=
</varname></term>
2612 <para>When true, the DHCPv4 configuration will be delayed by the timespan provided by the DHCP
2613 server and skip to configure dynamic IPv4 network connectivity if IPv6 connectivity is provided
2614 within the timespan. See
<ulink url=
"https://tools.ietf.org/html/rfc8925">RFC
8925</ulink>.
2615 Defaults to true when
<varname>IPv6AcceptRA=
</varname> is enabled or DHCPv6 client is enabled
2616 (i.e.,
<varname>DHCP=yes
</varname>), and false otherwise.
</para>
2618 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2623 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
2625 <para>Allows one to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease
2626 lifetime. Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal>. If
2627 specified, the acquired address never expires. Defaults to unset.
</para>
2629 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2633 <!-- How to communicate with the server -->
2636 <term><varname>RequestBroadcast=
</varname></term>
2638 <para>Request the server to use broadcast messages before the IP address has been configured.
2639 This is necessary for devices that cannot receive RAW packets, or that cannot receive packets
2640 at all before an IP address has been configured. On the other hand, this must not be enabled
2641 on networks where broadcasts are filtered out.
</para>
2643 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2648 <term><varname>MaxAttempts=
</varname></term>
2650 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
2651 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>. Note that the
2652 time between retries is increased exponentially, up to approximately one per minute, so the
2653 network will not be overloaded even if this number is high. The default is suitable in most
2654 circumstances.
</para>
2656 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2661 <term><varname>ListenPort=
</varname></term>
2663 <para>Set the port from which the DHCP client packets originate.
</para>
2665 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
2670 <term><varname>DenyList=
</varname></term>
2672 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2673 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are rejected.
2674 Note that if
<varname>AllowList=
</varname> is configured then
<varname>DenyList=
</varname> is
2676 <para>Note that this filters only DHCP offers, so the filtering may not work when
2677 <varname>RapidCommit=
</varname> is enabled. See also
<varname>RapidCommit=
</varname> in the above.
2680 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2685 <term><varname>AllowList=
</varname></term>
2687 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2688 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are accepted.
2690 <para>Note that this filters only DHCP offers, so the filtering may not work when
2691 <varname>RapidCommit=
</varname> is enabled. See also
<varname>RapidCommit=
</varname> in the above.
2694 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2699 <term><varname>SendRelease=
</varname></term>
2701 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops. Defaults to
2704 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2709 <term><varname>SendDecline=
</varname></term>
2711 <para>A boolean. When true,
<command>systemd-networkd
</command> performs IPv4 Duplicate
2712 Address Detection to the acquired address by the DHCPv4 client. If duplicate is detected,
2713 the DHCPv4 client rejects the address by sending a
<constant>DHCPDECLINE
</constant> packet to
2714 the DHCP server, and tries to obtain an IP address again. See
2715 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>. Defaults to false.
</para>
2717 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2722 <term><varname>NetLabel=
</varname></term>
2724 <para>This applies the NetLabel for the addresses received with DHCP, like
2725 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
2726 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
2728 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2733 <term><varname>NFTSet=
</varname></term>
2735 <para>This applies the NFT set for the network configuration received with DHCP, like
2736 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
2737 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
2738 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
2739 <literal>ipv4_addr
</literal>.
</para>
2741 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2748 <title>[DHCPv6] Section Options
</title>
2750 <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
2751 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
2754 <variablelist class='network-directives'
>
2756 <!-- DHCP packet contents -->
2759 <term><varname>MUDURL=
</varname></term>
2760 <term><varname>IAID=
</varname></term>
2761 <term><varname>DUIDType=
</varname></term>
2762 <term><varname>DUIDRawData=
</varname></term>
2763 <term><varname>RequestOptions=
</varname></term>
2765 <para>As in the [DHCPv4] section.
</para>
2767 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2772 <term><varname>SendOption=
</varname></term>
2774 <para>As in the [DHCPv4] section, however because DHCPv6 uses
16-bit fields to store option
2775 numbers, the option number is an integer in the range
1…
65536.
</para>
2777 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2782 <term><varname>SendVendorOption=
</varname></term>
2784 <para>Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier,
2785 DHCP option number, data type, and data separated with a colon
2786 (
<literal><replaceable>enterprise identifier
</replaceable>:
<replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2787 Enterprise identifier is an unsigned integer in the range
1…
4294967294. The option number
2788 must be an integer in the range
1…
254. Data type takes one of
<literal>uint8
</literal>,
2789 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
2790 <literal>ipv6address
</literal>, or
<literal>string
</literal>. Special characters in the data
2791 string may be escaped using
2792 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2793 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2794 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
2796 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2801 <term><varname>UserClass=
</varname></term>
2803 <para>A DHCPv6 client can use User Class option to identify the type or category of user or
2804 applications it represents. The information contained in this option is a string that
2805 represents the user class of which the client is a member. Each class sets an identifying
2806 string of information to be used by the DHCP service to classify clients. Special characters
2807 in the data string may be escaped using
2808 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2809 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2810 specified, then all options specified earlier are cleared. Takes a whitespace-separated list
2811 of strings. Note that currently
<constant>NUL
</constant> bytes are not allowed.
</para>
2813 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2818 <term><varname>VendorClass=
</varname></term>
2820 <para>A DHCPv6 client can use VendorClass option to identify the vendor that manufactured the
2821 hardware on which the client is running. The information contained in the data area of this
2822 option is contained in one or more opaque fields that identify details of the hardware
2823 configuration. Takes a whitespace-separated list of strings.
</para>
2825 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2830 <term><varname>PrefixDelegationHint=
</varname></term>
2832 <para>Takes an IPv6 address with prefix length in the same format as the
2833 <varname>Address=
</varname> in the [Network] section. The DHCPv6 client will include a prefix
2834 hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
2835 1…
128. Defaults to unset.
</para>
2837 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2842 <term><varname>RapidCommit=
</varname></term>
2844 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server
2845 through a rapid two-message exchange (solicit and reply). When the rapid commit option is set by
2846 both the DHCPv6 client and the DHCPv6 server, the two-message exchange is used. Otherwise, the
2847 four-message exchange (solicit, advertise, request, and reply) is used. The two-message exchange
2848 provides faster client configuration. See
2849 <ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
2850 Defaults to true, and the two-message exchange will be used if the server support it.
</para>
2852 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2857 <term><varname>SendHostname=
</varname></term>
2859 <para>When true (the default), the machine's hostname (or the value specified with
2860 <varname>Hostname=
</varname>, described below) will be sent to the DHCPv6 server. Note that the
2861 hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and be
2862 formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option
2865 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2870 <term><varname>Hostname=
</varname></term>
2872 <para>Use this value for the hostname which is sent to the DHCPv6 server, instead of machine's
2873 hostname. Note that the specified hostname must consist only of
7-bit ASCII lower-case
2874 characters and no spaces or dots, and be formatted as a valid DNS domain name.
</para>
2876 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2880 <!-- How to use the DHCP lease -->
2883 <term><varname>UseAddress=
</varname></term>
2885 <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
2888 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2893 <term><varname>UseCaptivePortal=
</varname></term>
2895 <para>When true (the default), the captive portal advertised by the DHCPv6 server will be recorded
2896 and made available to client programs and displayed in the
2897 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
2898 status output per-link.
</para>
2900 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
2905 <term><varname>UseDelegatedPrefix=
</varname></term>
2907 <para>When true (the default), the client will request the DHCPv6 server to delegate
2908 prefixes. If the server provides prefixes to be delegated, then subnets of the prefixes are
2909 assigned to the interfaces that have
<varname>DHCPPrefixDelegation=yes
</varname>.
2910 See also the
<varname>DHCPPrefixDelegation=
</varname> setting in the [Network] section,
2911 settings in the [DHCPPrefixDelegation] section, and
2912 <ulink url=
"https://www.rfc-editor.org/rfc/rfc8415.html#section-6.3">RFC
8415</ulink>.
2915 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2920 <term><varname>UseDNS=
</varname></term>
2921 <term><varname>UseNTP=
</varname></term>
2922 <term><varname>UseHostname=
</varname></term>
2923 <term><varname>UseDomains=
</varname></term>
2924 <term><varname>NetLabel=
</varname></term>
2925 <term><varname>SendRelease=
</varname></term>
2927 <para>As in the [DHCPv4] section.
</para>
2929 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2934 <term><varname>NFTSet=
</varname></term>
2936 <para>This applies the NFT set for the network configuration received with DHCP, like
2937 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
2938 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal>
2939 or
<literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
2940 <literal>ipv6_addr
</literal>.
</para>
2942 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2946 <!-- How to communicate with the server -->
2949 <term><varname>WithoutRA=
</varname></term>
2951 <para>Allows DHCPv6 client to start without router advertisements's
2952 <literal>managed
</literal> or
<literal>other configuration
</literal> flag. Takes one of
2953 <literal>no
</literal>,
<literal>solicit
</literal>, or
2954 <literal>information-request
</literal>. If this is not specified,
2955 <literal>solicit
</literal> is used when
<varname>DHCPPrefixDelegation=
</varname> is enabled
2956 and
<varname>UplinkInterface=:self
</varname> is specified in the [DHCPPrefixDelegation]
2957 section. Otherwise, defaults to
<literal>no
</literal>, and the DHCPv6 client will be started
2958 when an RA is received. See also the
<varname>DHCPv6Client=
</varname> setting in the
2959 [IPv6AcceptRA] section.
</para>
2961 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2968 <title>[DHCPPrefixDelegation] Section Options
</title>
2969 <para>The [DHCPPrefixDelegation] section configures subnet prefixes of the delegated prefixes
2970 acquired by a DHCPv6 client or by a DHCPv4 client through the
6RD option on another interface.
2971 The settings in this section are used only when the
<varname>DHCPPrefixDelegation=
</varname>
2972 setting in the [Network] section is enabled.
</para>
2974 <variablelist class='network-directives'
>
2976 <term><varname>UplinkInterface=
</varname></term>
2978 <para>Specifies the name or the index of the uplink interface, or one of the special values
2979 <literal>:self
</literal> and
<literal>:auto
</literal>. When
<literal>:self
</literal>, the
2980 interface itself is considered the uplink interface, and
2981 <varname>WithoutRA=solicit
</varname> is implied if the setting is not explicitly specified.
2982 When
<literal>:auto
</literal>, the first link which acquired prefixes to be delegated from
2983 the DHCPv6 or DHCPv4 server is selected. Defaults to
<literal>:auto
</literal>.
</para>
2985 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2990 <term><varname>SubnetId=
</varname></term>
2992 <para>Configure a specific subnet ID on the interface from a (previously) received prefix
2993 delegation. You can either set
"auto" (the default) or a specific subnet ID (as defined in
2994 <ulink url=
"https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC
4291</ulink>, section
2995 2.5.4), in which case the allowed value is hexadecimal, from
0 to
0x7fffffffffffffff
2998 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3003 <term><varname>Announce=
</varname></term>
3005 <para>Takes a boolean. When enabled, and
<varname>IPv6SendRA=
</varname> in [Network] section
3006 is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
3007 This setting will be ignored when the
<varname>DHCPPrefixDelegation=
</varname> setting is
3008 enabled on the upstream interface. Defaults to yes.
</para>
3010 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
3015 <term><varname>Assign=
</varname></term>
3017 <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
3018 are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
3019 interface), the EUI-
64 algorithm will be used by default to form an interface identifier from
3020 the delegated prefixes. See also
<varname>Token=
</varname> setting below. Defaults to yes.
3023 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3028 <term><varname>Token=
</varname></term>
3030 <para>Specifies an optional address generation mode for assigning an address in each
3031 delegated prefix. This accepts the same syntax as
<varname>Token=
</varname> in the
3032 [IPv6AcceptRA] section. If
<varname>Assign=
</varname> is set to false, then this setting will
3033 be ignored. Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
3035 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3040 <term><varname>ManageTemporaryAddress=
</varname></term>
3042 <para>As in the [Address] section, but defaults to true.
</para>
3044 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3049 <term><varname>RouteMetric=
</varname></term>
3051 <para>The metric of the route to the delegated prefix subnet. Takes an unsigned integer in
3052 the range
0…
4294967295. When set to
0, the kernel's default value is used. Defaults to
256.
3055 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3060 <term><varname>NetLabel=
</varname></term>
3062 <para>This applies the NetLabel for the addresses received with DHCP, like
3063 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
3064 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
3066 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
3071 <term><varname>NFTSet=
</varname></term>
3073 <para>This applies the NFT set for the network configuration received with DHCP, like
3074 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
3075 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
3076 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
3077 <literal>ipv6_addr
</literal>.
</para>
3079 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3086 <title>[IPv6AcceptRA] Section Options
</title>
3087 <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
3088 with the
<varname>IPv6AcceptRA=
</varname> setting described above:
</para>
3090 <variablelist class='network-directives'
>
3092 <term><varname>Token=
</varname></term>
3094 <para>Specifies an optional address generation mode for the Stateless Address
3095 Autoconfiguration (SLAAC). The following values are supported:
</para>
3099 <term><option>eui64
</option></term>
3102 The EUI-
64 algorithm will be used to generate an address for that prefix. Only
3103 supported by Ethernet or InfiniBand interfaces.
3106 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3110 <term><option>static:
<replaceable>ADDRESS
</replaceable></option></term>
3113 An IPv6 address must be specified after a colon (
<literal>:
</literal>), and the
3114 lower bits of the supplied address are combined with the upper bits of a prefix
3115 received in a Router Advertisement (RA) message to form a complete address. Note
3116 that if multiple prefixes are received in an RA message, or in multiple RA messages,
3117 addresses will be formed from each of them using the supplied address. This mode
3118 implements SLAAC but uses a static interface identifier instead of an identifier
3119 generated by using the EUI-
64 algorithm. Because the interface identifier is static,
3120 if Duplicate Address Detection detects that the computed address is a duplicate
3121 (in use by another node on the link), then this mode will fail to provide an address
3122 for that prefix. If an IPv6 address without mode is specified, then
3123 <literal>static
</literal> mode is assumed.
3126 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3130 <term><option>prefixstable[:
<replaceable>ADDRESS
</replaceable>][,
<replaceable>UUID
</replaceable>]
</option></term>
3133 The algorithm specified in
3134 <ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink> will be used to
3135 generate interface identifiers. This mode can optionally take an IPv6 address
3136 separated with a colon (
<literal>:
</literal>). If an IPv6 address is specified,
3137 then an interface identifier is generated only when a prefix received in an RA
3138 message matches the supplied address.
3141 This mode can also optionally take a non-null UUID in the format which
3142 <function>sd_id128_from_string()
</function> accepts, e.g.
3143 <literal>86b123b969ba4b7eb8b3d8605123525a
</literal> or
3144 <literal>86b123b9-
69ba-
4b7e-b8b3-d8605123525a
</literal>. If a UUID is specified, the
3145 value is used as the secret key to generate interface identifiers. If not specified,
3146 then an application specific ID generated with the system's machine-ID will be used
3147 as the secret key. See
3148 <citerefentry><refentrytitle>sd-id128
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
3149 <citerefentry><refentrytitle>sd_id128_from_string
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
3151 <citerefentry><refentrytitle>sd_id128_get_machine
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
3154 Note that the
<literal>prefixstable
</literal> algorithm uses both the interface
3155 name and MAC address as input to the hash to compute the interface identifier, so
3156 if either of those are changed the resulting interface identifier (and address)
3157 will be changed, even if the prefix received in the RA message has not been
3161 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3166 <para>If no address generation mode is specified (which is the default), or a received
3167 prefix does not match any of the addresses provided in
<literal>prefixstable
</literal>
3168 mode, then the EUI-
64 algorithm will be used for Ethernet or InfiniBand interfaces,
3169 otherwise
<literal>prefixstable
</literal> will be used to form an interface identifier for
3172 <para>This setting can be specified multiple times. If an empty string is assigned, then
3173 the all previous assignments are cleared.
</para>
3176 <programlisting>Token=eui64
3178 Token=static:::
1a:
2b:
3c:
4d
3180 Token=prefixstable:
2002:da8:
1::
</programlisting></para>
3182 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3187 <term><varname>UseDNS=
</varname></term>
3189 <para>When true (the default), the DNS servers received in the Router Advertisement will be used.
</para>
3191 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
3192 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3194 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
3199 <term><varname>UseDomains=
</varname></term>
3201 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
3202 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link,
3203 similarly to the effect of the
<option>Domains=
</option> setting. If set to
3204 <literal>route
</literal>, the domain name received via IPv6 RA will be used for routing DNS queries
3205 only, but not for searching, similarly to the effect of the
<option>Domains=
</option> setting when
3206 the argument is prefixed with
<literal>~
</literal>. Defaults to false.
</para>
3208 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
3209 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
3210 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
3211 single-label names.
</para>
3213 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
3214 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3216 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
3221 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
3223 <para>The table identifier for the routes received in the Router Advertisement. Takes one of
3224 predefined names
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
3225 and names defined in
<varname>RouteTable=
</varname> in
3226 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3227 or a number between
1…
4294967295.
</para>
3229 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
3230 used when this parameter is not specified.
</para>
3232 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
3237 <term><varname>RouteMetric=
</varname></term>
3239 <para>Set the routing metric for the routes received in the Router Advertisement. Takes an unsigned
3240 integer in the range
0…
4294967295, or three unsigned integer separated with
<literal>:
</literal>,
3241 in that case the first one is used when the router preference is high, the second is for medium
3242 preference, and the last is for low preference
3243 (
<literal><replaceable>high
</replaceable>:
<replaceable>medium
</replaceable>:
<replaceable>low
</replaceable></literal>).
3244 Defaults to
<literal>512:
1024:
2048</literal>.
</para>
3246 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3251 <term><varname>QuickAck=
</varname></term>
3253 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
3254 the received RAs. When unset, the kernel's default will be used.
</para>
3256 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
3261 <term><varname>UseMTU=
</varname></term>
3263 <para>Takes a boolean. When true, the MTU received in the Router Advertisement will be
3264 used. Defaults to true.
</para>
3266 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3271 <term><varname>UseHopLimit=
</varname></term>
3273 <para>Takes a boolean. When true, the hop limit received in the Router Advertisement will be set to routes
3274 configured based on the advertisement. See also
<varname>IPv6HopLimit=
</varname>. Defaults to true.
</para>
3276 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3281 <term><varname>UseICMP6RateLimit=
</varname></term>
3283 <para>Takes a boolean. When true, the ICMP6 rate limit received in the Router Advertisement will be set to ICMP6
3284 rate limit based on the advertisement. Defaults to true.
</para>
3286 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3291 <term><varname>UseGateway=
</varname></term>
3293 <para>When true (the default), the router address will be configured as the default gateway.
3296 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3301 <term><varname>UseRoutePrefix=
</varname></term>
3303 <para>When true (the default), the routes corresponding to the route prefixes received in
3304 the Router Advertisement will be configured.
</para>
3306 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3311 <term><varname>UseCaptivePortal=
</varname></term>
3313 <para>When true (the default), the captive portal received in the Router Advertisement will be recorded
3314 and made available to client programs and displayed in the
3315 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
3316 status output per-link.
</para>
3318 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
3323 <term><varname>UsePREF64=
</varname></term>
3325 <para>When true, the IPv6 PREF64 (or NAT64) prefixes received in the Router Advertisement will be
3326 recorded and made available to client programs and displayed in the
3327 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
3328 status output per-link. See
<ulink url=
"https://tools.ietf.org/html/rfc8781">RFC
8781</ulink>.
3329 Defaults to false.
</para>
3331 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3336 <term><varname>UseAutonomousPrefix=
</varname></term>
3338 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
3339 precedence over any statically configured ones.
</para>
3341 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
3346 <term><varname>UseOnLinkPrefix=
</varname></term>
3348 <para>When true (the default), the onlink prefix received in the Router Advertisement will be
3349 used and takes precedence over any statically configured ones.
</para>
3351 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
3356 <term><varname>RouterDenyList=
</varname></term>
3358 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
3359 take a prefix length after
<literal>/
</literal>. Any information advertised by the listed
3360 router is ignored.
</para>
3362 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3367 <term><varname>RouterAllowList=
</varname></term>
3369 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
3370 take a prefix length after
<literal>/
</literal>. Only information advertised by the listed
3371 router is accepted. Note that if
<varname>RouterAllowList=
</varname> is configured then
3372 <varname>RouterDenyList=
</varname> is ignored.
</para>
3374 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3379 <term><varname>PrefixDenyList=
</varname></term>
3381 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
3382 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
3383 in the list are ignored.
</para>
3385 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3390 <term><varname>PrefixAllowList=
</varname></term>
3392 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
3393 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
3394 in the list are allowed. Note that if
<varname>PrefixAllowList=
</varname> is configured
3395 then
<varname>PrefixDenyList=
</varname> is ignored.
</para>
3397 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3402 <term><varname>RouteDenyList=
</varname></term>
3404 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
3405 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
3406 advertisements in the list are ignored.
</para>
3408 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3413 <term><varname>RouteAllowList=
</varname></term>
3415 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
3416 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
3417 advertisements in the list are allowed. Note that if
<varname>RouteAllowList=
</varname> is
3418 configured then
<varname>RouteDenyList=
</varname> is ignored.
</para>
3420 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3425 <term><varname>DHCPv6Client=
</varname></term>
3427 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true, the
3428 DHCPv6 client will be started in
<literal>solicit
</literal> mode if the RA has the
3429 <literal>managed
</literal> flag or
<literal>information-request
</literal> mode if the RA
3430 lacks the
<literal>managed
</literal> flag but has the
3431 <literal>other configuration
</literal> flag. If set to
<literal>always
</literal>, the
3432 DHCPv6 client will be started in
<literal>solicit
</literal> mode when an RA is received,
3433 even if neither the
<literal>managed
</literal> nor the
3434 <literal>other configuration
</literal> flag is set in the RA. This will be ignored when
3435 <varname>WithoutRA=
</varname> in the [DHCPv6] section is enabled, or
3436 <varname>UplinkInterface=:self
</varname> in the [DHCPPrefixDelegation] section is
3437 specified. Defaults to true.
</para>
3439 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3444 <term><varname>NetLabel=
</varname></term>
3446 <para>This applies the NetLabel for the addresses received with RA, like
3447 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
3448 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
3450 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
3455 <term><varname>NFTSet=
</varname></term>
3457 <para>This applies the NFT set for the network configuration received with RA, like
3458 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
3459 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
3460 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
3461 <literal>ipv6_addr
</literal>.
</para>
3463 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3470 <title>[DHCPServer] Section Options
</title>
3471 <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
3472 <varname>DHCPServer=
</varname> option described above:
</para>
3474 <variablelist class='network-directives'
>
3477 <term><varname>ServerAddress=
</varname></term>
3479 <para>Specifies the server address for the DHCP server. Takes an IPv4 address with prefix length
3480 separated with a slash, e.g.
<literal>192.168.0.1/
24</literal>. Defaults to unset, and one of
3481 static IPv4 addresses configured in [Network] or [Address] section will be automatically selected.
3482 This setting may be useful when the interface on which the DHCP server is running has multiple
3483 static IPv4 addresses.
</para>
3484 <para>This implies
<varname>Address=
</varname> in [Network] or [Address] section with the same
3485 address and prefix length. That is,
3486 <programlisting>[Network]
3488 Address=
192.168.0.1/
24
3489 Address=
192.168.0.2/
24
3491 ServerAddress=
192.168.0.1/
24</programlisting>
3493 <programlisting>[Network]
3496 Address=
192.168.0.1/
24
3498 Address=
192.168.0.2/
24
3500 ServerAddress=
192.168.0.1/
24</programlisting>
3501 are equivalent to the following.
3502 <programlisting>[Network]
3504 Address=
192.168.0.2/
24
3506 ServerAddress=
192.168.0.1/
24</programlisting>
3508 <para>Since version
255, like the
<varname>Address=
</varname> setting in [Network] or [Address]
3509 section, this also supports a null address, e.g.
<literal>0.0.0.0/
24</literal>, and an unused
3510 address will be automatically selected. For more details about the automatic address selection,
3511 see
<varname>Address=
</varname> setting in [Network] section in the above.
</para>
3513 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3518 <term><varname>PoolOffset=
</varname></term>
3519 <term><varname>PoolSize=
</varname></term>
3521 <listitem><para>Configures the pool of addresses to hand out. The pool
3522 is a contiguous sequence of IP addresses in the subnet configured for
3523 the server address, which does not include the subnet nor the broadcast
3524 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
3525 from the start of subnet, or zero to use the default value.
3526 <varname>PoolSize=
</varname> takes the number of IP addresses in the
3527 pool or zero to use the default value. By default, the pool starts at
3528 the first address after the subnet address and takes up the rest of
3529 the subnet, excluding the broadcast address. If the pool includes
3530 the server address (the default), this is reserved and not handed
3531 out to clients.
</para>
3533 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3537 <term><varname>DefaultLeaseTimeSec=
</varname></term>
3538 <term><varname>MaxLeaseTimeSec=
</varname></term>
3540 <listitem><para>Control the default and maximum DHCP lease
3541 time to pass to clients. These settings take time values in seconds or
3542 another common time unit, depending on the suffix. The default
3543 lease time is used for clients that did not ask for a specific
3544 lease time. If a client asks for a lease time longer than the
3545 maximum lease time, it is automatically shortened to the
3546 specified time. The default lease time defaults to
1h, the
3547 maximum lease time to
12h. Shorter lease times are beneficial
3548 if the configuration data in DHCP leases changes frequently
3549 and clients shall learn the new settings with shorter
3550 latencies. Longer lease times reduce the generated DHCP
3551 network traffic.
</para>
3553 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3557 <term><varname>UplinkInterface=
</varname></term>
3558 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
3559 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS, NTP, or SIP
3560 servers is enabled but no servers are specified, the servers configured in the uplink interface
3561 will be emitted. When
<literal>:auto
</literal>, the link which has a default gateway with the
3562 highest priority will be automatically selected. When
<literal>:none
</literal>, no uplink
3563 interface will be selected. Defaults to
<literal>:auto
</literal>.
</para>
3565 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3569 <term><varname>EmitDNS=
</varname></term>
3570 <term><varname>DNS=
</varname></term>
3572 <listitem><para><varname>EmitDNS=
</varname> takes a boolean. Configures whether the DHCP leases
3573 handed out to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
3574 The DNS servers to pass to clients may be configured with the
<varname>DNS=
</varname> option,
3575 which takes a list of IPv4 addresses, or special value
<literal>_server_address
</literal> which
3576 will be converted to the address used by the DHCP server.
</para>
3578 <para>If the
<varname>EmitDNS=
</varname> option is enabled but no servers configured, the
3579 servers are automatically propagated from an
"uplink" interface that has appropriate servers
3580 set. The
"uplink" interface is determined by the default route of the system with the highest
3581 priority. Note that this information is acquired at the time the lease is handed out, and does
3582 not take uplink interfaces into account that acquire DNS server information at a later point.
3583 If no suitable uplink interface is found the DNS server data from
3584 <filename>/etc/resolv.conf
</filename> is used. Also, note that the leases are not refreshed if
3585 the uplink network configuration changes. To ensure clients regularly acquire the most current
3586 uplink DNS server information, it is thus advisable to shorten the DHCP lease time via
3587 <varname>MaxLeaseTimeSec=
</varname> described above.
</para>
3589 <para>This setting can be specified multiple times. If an empty string is specified, then all
3590 DNS servers specified earlier are cleared.
</para>
3592 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3596 <term><varname>EmitNTP=
</varname></term>
3597 <term><varname>NTP=
</varname></term>
3598 <term><varname>EmitSIP=
</varname></term>
3599 <term><varname>SIP=
</varname></term>
3600 <term><varname>EmitPOP3=
</varname></term>
3601 <term><varname>POP3=
</varname></term>
3602 <term><varname>EmitSMTP=
</varname></term>
3603 <term><varname>SMTP=
</varname></term>
3604 <term><varname>EmitLPR=
</varname></term>
3605 <term><varname>LPR=
</varname></term>
3607 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname> settings
3608 described above, these settings configure whether and what server information for the indicate
3609 protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
3610 defaults apply as for
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname>.
</para>
3612 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3616 <term><varname>EmitRouter=
</varname></term>
3617 <term><varname>Router=
</varname></term>
3619 <listitem><para>The
<varname>EmitRouter=
</varname> setting takes a boolean value, and configures
3620 whether the DHCP lease should contain the router option. The
<varname>Router=
</varname> setting
3621 takes an IPv4 address, and configures the router address to be emitted. When the
3622 <varname>Router=
</varname> setting is not specified, then the server address will be used for
3623 the router option. When the
<varname>EmitRouter=
</varname> setting is disabled, the
3624 <varname>Router=
</varname> setting will be ignored. The
<varname>EmitRouter=
</varname> setting
3625 defaults to true, and the
<varname>Router=
</varname> setting defaults to unset.
3628 <xi:include href=
"version-info.xml" xpointer=
"v230"/></listitem>
3632 <term><varname>EmitTimezone=
</varname></term>
3633 <term><varname>Timezone=
</varname></term>
3635 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
3636 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
3637 <varname>Timezone=
</varname> setting takes a timezone string
3638 (such as
<literal>Europe/Berlin
</literal> or
3639 <literal>UTC
</literal>) to pass to clients. If no explicit
3640 timezone is set, the system timezone of the local host is
3641 propagated, as determined by the
3642 <filename>/etc/localtime
</filename> symlink.
</para>
3644 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3648 <term><varname>BootServerAddress=
</varname></term>
3651 <para>Takes an IPv4 address of the boot server used by e.g. PXE boot systems. When specified, this
3652 address is sent in the
<option>siaddr
</option> field of the DHCP message header. See
<ulink
3653 url=
"https://www.rfc-editor.org/rfc/rfc2131.html">RFC
2131</ulink> for more details. Defaults to
3656 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3661 <term><varname>BootServerName=
</varname></term>
3664 <para>Takes a name of the boot server used by e.g. PXE boot systems. When specified, this name is
3665 sent in the DHCP option
66 (
"TFTP server name"). See
<ulink
3666 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
3669 <para>Note that typically setting one of
<varname>BootServerName=
</varname> or
3670 <varname>BootServerAddress=
</varname> is sufficient, but both can be set too, if desired.
</para>
3672 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3677 <term><varname>BootFilename=
</varname></term>
3680 <para>Takes a path or URL to a file loaded by e.g. a PXE boot loader. When specified, this path is
3681 sent in the DHCP option
67 (
"Bootfile name"). See
<ulink
3682 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
3685 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3690 <term><varname>IPv6OnlyPreferredSec=
</varname></term>
3693 <para>Takes a timespan. Controls the
3694 <ulink url=
"https://tools.ietf.org/html/rfc8925">RFC
8925</ulink> IPv6-Only Preferred option.
3695 Specifies the DHCPv4 option to indicate that a host supports an IPv6-only mode and is willing to
3696 forgo obtaining an IPv4 address if the network provides IPv6 connectivity. Defaults to unset, and
3697 not send the option. The minimum allowed value is
300 seconds.
</para>
3699 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3704 <term><varname>SendOption=
</varname></term>
3706 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
3707 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
3708 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
3709 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
3710 <literal>string
</literal>. Special characters in the data string may be escaped using
3711 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
3712 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
3713 then all options specified earlier are cleared. Defaults to unset.
</para>
3715 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
3720 <term><varname>SendVendorOption=
</varname></term>
3722 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
3723 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
3724 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
3725 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
3726 <literal>string
</literal>. Special characters in the data string may be escaped using
3727 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
3728 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
3729 then all options specified earlier are cleared. Defaults to unset.
</para>
3731 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3735 <term><varname>BindToInterface=
</varname></term>
3737 <para>Takes a boolean value. When
<literal>yes
</literal>, DHCP server socket will be bound
3738 to its network interface and all socket communication will be restricted to this interface.
3739 Defaults to
<literal>yes
</literal>, except if
<varname>RelayTarget=
</varname> is used (see below),
3740 in which case it defaults to
<literal>no
</literal>.
</para>
3742 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3746 <term><varname>RelayTarget=
</varname></term>
3748 <para>Takes an IPv4 address, which must be in the format described in
3749 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
3750 Turns this DHCP server into a DHCP relay agent. See
<ulink url=
"https://tools.ietf.org/html/rfc1542">RFC
1542</ulink>.
3751 The address is the address of DHCP server or another relay agent to forward DHCP messages to and from.
</para>
3753 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3757 <term><varname>RelayAgentCircuitId=
</varname></term>
3759 <para>Specifies value for Agent Circuit ID suboption of Relay Agent Information option.
3760 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
3761 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
3762 Defaults to unset (means no Agent Circuit ID suboption is generated).
3763 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3765 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3769 <term><varname>RelayAgentRemoteId=
</varname></term>
3771 <para>Specifies value for Agent Remote ID suboption of Relay Agent Information option.
3772 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
3773 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
3774 Defaults to unset (means no Agent Remote ID suboption is generated).
3775 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3777 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3782 <term><varname>RapidCommit=
</varname></term>
3784 <para>Takes a boolean. When true, the server supports
3785 <ulink url=
"https://datatracker.ietf.org/doc/html/rfc4039">RFC
4039</ulink>. When a client sends
3786 a DHCPDISCOVER message with the Rapid Commit option to the server, then the server will reply with
3787 a DHCPACK message to the client, instead of DHCPOFFER. Defaults to true.
</para>
3789 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3797 <title>[DHCPServerStaticLease] Section Options
</title>
3798 <para>The
<literal>[DHCPServerStaticLease]
</literal> section configures a static DHCP lease to assign a
3799 fixed IPv4 address to a specific device based on its MAC address. This section can be specified multiple
3802 <variablelist class='network-directives'
>
3804 <term><varname>MACAddress=
</varname></term>
3806 <listitem><para>The hardware address of a device to match. This key is mandatory.
</para>
3808 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3812 <term><varname>Address=
</varname></term>
3814 <listitem><para>The IPv4 address that should be assigned to the device that was matched with
3815 <varname>MACAddress=
</varname>. This key is mandatory.
</para>
3817 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3823 <title>[IPv6SendRA] Section Options
</title>
3824 <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
3825 to act as a router, if enabled via the
<varname>IPv6SendRA=
</varname> option described above. IPv6
3826 network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
3829 <variablelist class='network-directives'
>
3832 <term><varname>Managed=
</varname></term>
3833 <term><varname>OtherInformation=
</varname></term>
3835 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
3836 addresses on the network link when
<varname>Managed=
</varname>
3837 is set to
<literal>true
</literal> or if only additional network
3838 information can be obtained via DHCPv6 for the network link when
3839 <varname>OtherInformation=
</varname> is set to
3840 <literal>true
</literal>. Both settings default to
3841 <literal>false
</literal>, which means that a DHCPv6 server is not being
3844 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3848 <term><varname>RouterLifetimeSec=
</varname></term>
3850 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. The value must be
0
3851 seconds, or between
4 seconds and
9000 seconds. When set to
0, the host is not acting as a router.
3852 Defaults to
1800 seconds (
30 minutes).
</para>
3854 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
3859 <term><varname>RetransmitSec=
</varname></term>
3861 <listitem><para>Takes a timespan. Configures the retransmit time, used by clients to retransmit Neighbor
3862 Solicitation messages on address resolution and the Neighbor Unreachability Detection algorithm.
3863 An integer the default unit of seconds, in the range
0…
4294967295 msec. Defaults to
0.
</para>
3865 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3870 <term><varname>RouterPreference=
</varname></term>
3872 <listitem><para>Configures IPv6 router preference if
3873 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
3874 <literal>high
</literal>,
<literal>medium
</literal> and
3875 <literal>low
</literal>, with
<literal>normal
</literal> and
3876 <literal>default
</literal> added as synonyms for
3877 <literal>medium
</literal> just to make configuration easier. See
3878 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
3879 for details. Defaults to
<literal>medium
</literal>.
</para>
3881 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3885 <term><varname>HopLimit=
</varname></term>
3887 <para>Configures hop limit. Takes an integer in the range
0…
255. See also
3888 <varname>IPv6HopLimit=
</varname>.
</para>
3890 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3895 <term><varname>UplinkInterface=
</varname></term>
3896 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
3897 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS servers or
3898 search domains is enabled but no servers are specified, the servers configured in the uplink
3899 interface will be emitted. When
<literal>:auto
</literal>, the value specified to the same
3900 setting in the [DHCPPrefixDelegation] section will be used if
3901 <varname>DHCPPrefixDelegation=
</varname> is enabled, otherwise the link which has a default
3902 gateway with the highest priority will be automatically selected. When
<literal>:none
</literal>,
3903 no uplink interface will be selected. Defaults to
<literal>:auto
</literal>.
</para>
3905 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
3909 <term><varname>EmitDNS=
</varname></term>
3910 <term><varname>DNS=
</varname></term>
3912 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
3913 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is true.
3914 <varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that case
3915 the IPv6 link-local address is distributed. If
<varname>DNS=
</varname> is empty, DNS servers are
3916 read from the [Network] section. If the [Network] section does not contain any DNS servers
3917 either, DNS servers from the uplink interface specified in
<varname>UplinkInterface=
</varname>
3918 will be used. When
<varname>EmitDNS=
</varname> is false, no DNS server information is sent in
3919 Router Advertisement messages.
<varname>EmitDNS=
</varname> defaults to true.
</para>
3921 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3925 <term><varname>EmitDomains=
</varname></term>
3926 <term><varname>Domains=
</varname></term>
3928 <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
3929 <varname>EmitDomains=
</varname> is true. If
<varname>Domains=
</varname> is empty, DNS search
3930 domains are read from the [Network] section. If the [Network] section does not contain any DNS
3931 search domains either, DNS search domains from the uplink interface specified in
3932 <varname>UplinkInterface=
</varname> will be used. When
<varname>EmitDomains=
</varname> is false,
3933 no DNS search domain information is sent in Router Advertisement messages.
3934 <varname>EmitDomains=
</varname> defaults to true.
</para>
3936 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3940 <term><varname>DNSLifetimeSec=
</varname></term>
3942 <listitem><para>Lifetime in seconds for the DNS server addresses listed in
3943 <varname>DNS=
</varname> and search domains listed in
<varname>Domains=
</varname>. Defaults to
3944 3600 seconds (one hour).
</para>
3946 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3950 <term><varname>HomeAgent=
</varname></term>
3952 <listitem><para>Takes a boolean. Specifies that IPv6 router advertisements which indicates to hosts that
3953 the router acts as a Home Agent and includes a Home Agent Option. Defaults to false. See
3954 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink> for further details.
</para>
3956 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3961 <term><varname>HomeAgentLifetimeSec=
</varname></term>
3963 <listitem><para>Takes a timespan. Specifies the lifetime of the Home Agent. An integer the default unit of seconds,
3964 in the range
1…
65535. Defaults to the value set to
<varname>RouterLifetimeSec=
</varname>.
</para>
3966 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3971 <term><varname>HomeAgentPreference=
</varname></term>
3973 <listitem><para>Configures IPv6 Home Agent preference. Takes an integer in the range
0…
65535.
3974 Defaults to
0.
</para>
3976 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3984 <title>[IPv6Prefix] Section Options
</title>
3985 <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
3986 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink> for further
3989 <variablelist class='network-directives'
>
3992 <term><varname>AddressAutoconfiguration=
</varname></term>
3993 <term><varname>OnLink=
</varname></term>
3995 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
3996 autoconfigured with this prefix and whether the prefix can be used for
3997 onlink determination. Both settings default to
<literal>true
</literal>
3998 in order to ease configuration.
4001 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
4005 <term><varname>Prefix=
</varname></term>
4007 <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
4008 IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
4009 <literal>/
</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
4010 prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
4011 prefix to another.
</para>
4013 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
4017 <term><varname>PreferredLifetimeSec=
</varname></term>
4018 <term><varname>ValidLifetimeSec=
</varname></term>
4020 <listitem><para>Preferred and valid lifetimes for the prefix measured in seconds.
4021 <varname>PreferredLifetimeSec=
</varname> defaults to
1800 seconds (
30 minutes) and
4022 <varname>ValidLifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para>
4024 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
4028 <term><varname>Assign=
</varname></term>
4029 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
4032 <xi:include href=
"version-info.xml" xpointer=
"v246"/></listitem>
4036 <term><varname>Token=
</varname></term>
4038 <para>Specifies an optional address generation mode for assigning an address in each
4039 prefix. This accepts the same syntax as
<varname>Token=
</varname> in the [IPv6AcceptRA]
4040 section. If
<varname>Assign=
</varname> is set to false, then this setting will be ignored.
4041 Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
4043 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4048 <term><varname>RouteMetric=
</varname></term>
4050 <para>The metric of the prefix route. Takes an unsigned integer in the range
0…
4294967295.
4051 When unset or set to
0, the kernel's default value is used. This setting is ignored when
4052 <varname>Assign=
</varname> is false.
</para>
4054 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
4061 <title>[IPv6RoutePrefix] Section Options
</title>
4062 <para>One or more [IPv6RoutePrefix] sections contain the IPv6
4063 prefix routes that are announced via Router Advertisements. See
4064 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
4065 for further details.
</para>
4067 <variablelist class='network-directives'
>
4070 <term><varname>Route=
</varname></term>
4072 <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
4073 IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
4074 separated by a
<literal>/
</literal> character. Use multiple [IPv6RoutePrefix] sections to configure
4075 multiple IPv6 prefix routes.
</para>
4077 <xi:include href=
"version-info.xml" xpointer=
"v244"/></listitem>
4081 <term><varname>LifetimeSec=
</varname></term>
4083 <listitem><para>Lifetime for the route prefix measured in seconds.
4084 <varname>LifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para>
4086 <xi:include href=
"version-info.xml" xpointer=
"v244"/></listitem>
4093 <title>[IPv6PREF64Prefix] Section Options
</title>
4094 <para>One or more [IPv6PREF64Prefix] sections contain the IPv6 PREF64 (or NAT64) prefixes that are announced via Router
4095 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc8781">RFC
8781</ulink> for further
4098 <variablelist class='network-directives'
>
4101 <term><varname>Prefix=
</varname></term>
4103 <listitem><para>The IPv6 PREF64 (or NAT64) prefix that is to be distributed to hosts. The setting holds
4104 an IPv6 prefix that should be set up for NAT64 translation (PLAT) to allow
464XLAT on the network segment.
4105 Use multiple [IPv6PREF64Prefix] sections to configure multiple IPv6 prefixes since prefix lifetime may differ
4106 from one prefix to another. The prefix is an address with a prefix length, separated by a slash
4107 <literal>/
</literal> character. Valid NAT64 prefix length are
96,
64,
56,
48,
40, and
32 bits.
</para>
4109 <xi:include href=
"version-info.xml" xpointer=
"v255"/></listitem></varlistentry>
4112 <term><varname>LifetimeSec=
</varname></term>
4113 <listitem><para>Lifetime for the prefix measured in seconds. Should be greater than or equal to
<varname>RouterLifetimeSec=
</varname>.
4114 <varname>LifetimeSec=
</varname> defaults to
1800 seconds.
</para>
4116 <xi:include href=
"version-info.xml" xpointer=
"v255"/></listitem>
4122 <title>[Bridge] Section Options
</title>
4123 <para>The [Bridge] section accepts the following keys:
</para>
4125 <variablelist class='network-directives'
>
4127 <term><varname>UnicastFlood=
</varname></term>
4129 <para>Takes a boolean. Controls whether the bridge should flood
4130 traffic for which an FDB entry is missing and the destination
4131 is unknown through this port. When unset, the kernel's default will be used.
4134 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4138 <term><varname>MulticastFlood=
</varname></term>
4140 <para>Takes a boolean. Controls whether the bridge should flood
4141 traffic for which an MDB entry is missing and the destination
4142 is unknown through this port. When unset, the kernel's default will be used.
4145 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4149 <term><varname>MulticastToUnicast=
</varname></term>
4151 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
4152 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
4153 When unset, the kernel's default will be used.
4156 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
4160 <term><varname>NeighborSuppression=
</varname></term>
4162 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
4163 this port. When unset, the kernel's default will be used.
4166 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4170 <term><varname>Learning=
</varname></term>
4172 <para>Takes a boolean. Configures whether MAC address learning is enabled for
4173 this port. When unset, the kernel's default will be used.
4176 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4180 <term><varname>HairPin=
</varname></term>
4182 <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
4183 was received. When this flag is false, then the bridge will not forward traffic back out of the
4184 receiving port. When unset, the kernel's default will be used.
</para>
4186 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4190 <term><varname>Isolated=
</varname></term>
4192 <para>Takes a boolean. Configures whether this port is isolated or not. Within a bridge,
4193 isolated ports can only communicate with non-isolated ports. When set to true, this port can only
4194 communicate with other ports whose Isolated setting is false. When set to false, this port
4195 can communicate with any other ports. When unset, the kernel's default will be used.
</para>
4197 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
4201 <term><varname>UseBPDU=
</varname></term>
4203 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
4204 processed by the bridge port. When unset, the kernel's default will be used.
</para>
4206 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4210 <term><varname>FastLeave=
</varname></term>
4212 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
4213 traffic on a port that receives an IGMP Leave message. It is only used with
4214 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
4216 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4220 <term><varname>AllowPortToBeRoot=
</varname></term>
4222 <para>Takes a boolean. Configures whether a given port is allowed to
4223 become a root port. Only used when STP is enabled on the bridge.
4224 When unset, the kernel's default will be used.
</para>
4226 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4230 <term><varname>ProxyARP=
</varname></term>
4232 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
4233 When unset, the kernel's default will be used.
</para>
4235 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4239 <term><varname>ProxyARPWiFi=
</varname></term>
4241 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
4242 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
4243 When unset, the kernel's default will be used.
</para>
4245 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4249 <term><varname>MulticastRouter=
</varname></term>
4251 <para>Configures this port for having multicast routers attached. A port with a multicast
4252 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
4253 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
4254 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
4255 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
4256 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
4258 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4262 <term><varname>Cost=
</varname></term>
4264 <para>Sets the
"cost" of sending packets of this interface.
4265 Each port in a bridge may have a different speed and the cost
4266 is used to decide which link to use. Faster interfaces
4267 should have lower costs. It is an integer value between
1 and
4270 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
4274 <term><varname>Priority=
</varname></term>
4276 <para>Sets the
"priority" of sending packets on this interface.
4277 Each port in a bridge may have a different priority which is used
4278 to decide which link to use. Lower value means higher priority.
4279 It is an integer value between
0 to
63. Networkd does not set any
4280 default, meaning the kernel default value of
32 is used.
</para>
4282 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
4289 <title>[BridgeFDB] Section Options
</title>
4291 <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
4292 keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.
</para>
4294 <variablelist class='network-directives'
>
4296 <term><varname>MACAddress=
</varname></term>
4298 <para>As in the [Network] section. This key is mandatory.
</para>
4300 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
4304 <term><varname>Destination=
</varname></term>
4306 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
4308 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4312 <term><varname>VLANId=
</varname></term>
4314 <para>The VLAN ID for the new static MAC table entry. If
4315 omitted, no VLAN ID information is appended to the new static MAC
4318 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
4322 <term><varname>VNI=
</varname></term>
4324 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
4325 the remote VXLAN tunnel endpoint. Takes a number in the range
1…
16777215.
4326 Defaults to unset.
</para>
4328 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4332 <term><varname>AssociatedWith=
</varname></term>
4334 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
4335 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
4336 <literal>use
</literal> means the address is in use. User space can use this option to
4337 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
4338 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
4339 means the address is associated with master devices fdb.
<literal>router
</literal> means
4340 the destination address is associated with a router. Note that it's valid if the referenced
4341 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
4343 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4347 <term><varname>OutgoingInterface=
</varname></term>
4349 <para>Specifies the name or index of the outgoing interface for the VXLAN device driver to
4350 reach the remote VXLAN tunnel endpoint. Defaults to unset.
</para>
4352 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
4359 <title>[BridgeMDB] Section Options
</title>
4360 <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
4361 keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.
</para>
4363 <variablelist class='network-directives'
>
4365 <term><varname>MulticastGroupAddress=
</varname></term>
4367 <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.
</para>
4369 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4373 <term><varname>VLANId=
</varname></term>
4375 <para>The VLAN ID for the new entry. Valid ranges are
0 (no VLAN) to
4094. Optional, defaults to
0.
</para>
4377 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4384 <title>[LLDP] Section Options
</title>
4385 <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
4388 <variablelist class='network-directives'
>
4390 <term><varname>MUDURL=
</varname></term>
4392 <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
4393 LLDP packets. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
4394 [DHCPv4] section described above.
</para>
4396 <para>The MUD URLs received via LLDP packets are saved and can be read using the
4397 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
4399 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4406 <title>[CAN] Section Options
</title>
4407 <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
4408 following keys:
</para>
4409 <variablelist class='network-directives'
>
4411 <term><varname>BitRate=
</varname></term>
4413 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
4414 be used here. Takes a number in the range
1…
4294967295.
</para>
4416 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4420 <term><varname>SamplePoint=
</varname></term>
4422 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
4423 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>). This will be ignored when
4424 <varname>BitRate=
</varname> is unspecified.
</para>
4426 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4430 <term><varname>TimeQuantaNSec=
</varname></term>
4431 <term><varname>PropagationSegment=
</varname></term>
4432 <term><varname>PhaseBufferSegment1=
</varname></term>
4433 <term><varname>PhaseBufferSegment2=
</varname></term>
4434 <term><varname>SyncJumpWidth=
</varname></term>
4436 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
4437 synchronization jump width, which allow one to define the CAN bit-timing in a hardware
4438 independent format as proposed by the Bosch CAN
2.0 Specification.
4439 <varname>TimeQuantaNSec=
</varname> takes a timespan in nanoseconds.
4440 <varname>PropagationSegment=
</varname>,
<varname>PhaseBufferSegment1=
</varname>,
4441 <varname>PhaseBufferSegment2=
</varname>, and
<varname>SyncJumpWidth=
</varname> take number
4442 of time quantum specified in
<varname>TimeQuantaNSec=
</varname> and must be an unsigned
4443 integer in the range
0…
4294967295. These settings except for
4444 <varname>SyncJumpWidth=
</varname> will be ignored when
<varname>BitRate=
</varname> is
4447 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4451 <term><varname>DataBitRate=
</varname></term>
4452 <term><varname>DataSamplePoint=
</varname></term>
4454 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
4455 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
4457 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4461 <term><varname>DataTimeQuantaNSec=
</varname></term>
4462 <term><varname>DataPropagationSegment=
</varname></term>
4463 <term><varname>DataPhaseBufferSegment1=
</varname></term>
4464 <term><varname>DataPhaseBufferSegment2=
</varname></term>
4465 <term><varname>DataSyncJumpWidth=
</varname></term>
4467 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
4468 synchronization jump width for the data phase, if CAN-FD is used. These settings are
4469 analogous to the
<varname>TimeQuantaNSec=
</varname> or related settings.
</para>
4471 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4475 <term><varname>FDMode=
</varname></term>
4477 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
4478 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
4479 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys, or
4480 <varname>DataTimeQuanta=
</varname> and related settings.
</para>
4482 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4486 <term><varname>FDNonISO=
</varname></term>
4488 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
4489 interface. When unset, the kernel's default will be used.
</para>
4491 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4495 <term><varname>RestartSec=
</varname></term>
4497 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
4498 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
4499 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
4500 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
4501 automatic restart off. By default automatic restart is disabled.
</para>
4503 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4507 <term><varname>Termination=
</varname></term>
4509 <para>Takes a boolean or a termination resistor value in ohm in the range
0…
65535. When
4510 <literal>yes
</literal>, the termination resistor is set to
120 ohm. When
4511 <literal>no
</literal> or
<literal>0</literal> is set, the termination resistor is disabled.
4512 When unset, the kernel's default will be used.
</para>
4514 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4518 <term><varname>TripleSampling=
</varname></term>
4520 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
4521 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
4523 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4527 <term><varname>BusErrorReporting=
</varname></term>
4529 <para>Takes a boolean. When
<literal>yes
</literal>, reporting of CAN bus errors is activated
4530 (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
4531 unable to send recessive bit, bus overload, active error announcement, error occurred on
4532 transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
4533 single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.
</para>
4535 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
4539 <term><varname>ListenOnly=
</varname></term>
4541 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
4542 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
4543 bit. Listen-only mode is important to debug CAN networks without interfering with the
4544 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
4547 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4551 <term><varname>Loopback=
</varname></term>
4553 <para>Takes a boolean. When
<literal>yes
</literal>, loopback mode is enabled. When the
4554 loopback mode is enabled, the interface treats messages transmitted by itself as received
4555 messages. The loopback mode is important to debug CAN networks. When unset, the kernel's
4556 default will be used.
</para>
4558 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4562 <term><varname>OneShot=
</varname></term>
4564 <para>Takes a boolean. When
<literal>yes
</literal>, one-shot mode is enabled. When unset,
4565 the kernel's default will be used.
</para>
4567 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4571 <term><varname>PresumeAck=
</varname></term>
4573 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will ignore missing CAN
4574 ACKs. When unset, the kernel's default will be used.
</para>
4576 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4580 <term><varname>ClassicDataLengthCode=
</varname></term>
4582 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will handle the
4bit data
4583 length code (DLC). When unset, the kernel's default will be used.
</para>
4585 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4592 <title>[IPoIB] Section Options
</title>
4593 <para>The [IPoIB] section manages the IP over Infiniband and accepts the following keys:
</para>
4595 <variablelist class='network-directives'
>
4596 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_mode" />
4597 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_umcast" />
4602 <title>[QDisc] Section Options
</title>
4603 <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).
</para>
4605 <variablelist class='network-directives'
>
4607 <term><varname>Parent=
</varname></term>
4609 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
4610 or
<literal>ingress
</literal>. This is mandatory.
</para>
4612 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
4616 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4621 <title>[NetworkEmulator] Section Options
</title>
4622 <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
4623 can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
4624 applications, or limit the bandwidth usage of a particular service to simulate internet connections.
4627 <variablelist class='network-directives'
>
4628 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4629 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4632 <term><varname>DelaySec=
</varname></term>
4634 <para>Specifies the fixed amount of delay to be added to all packets going out of the
4635 interface. Defaults to unset.
</para>
4637 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4642 <term><varname>DelayJitterSec=
</varname></term>
4644 <para>Specifies the chosen delay to be added to the packets outgoing to the network
4645 interface. Defaults to unset.
</para>
4647 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4652 <term><varname>PacketLimit=
</varname></term>
4654 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
4655 An unsigned integer in the range
0…
4294967294. Defaults to
1000.
</para>
4657 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4662 <term><varname>LossRate=
</varname></term>
4664 <para>Specifies an independent loss probability to be added to the packets outgoing from the
4665 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
4667 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4672 <term><varname>DuplicateRate=
</varname></term>
4674 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
4675 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
4677 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4684 <title>[TokenBucketFilter] Section Options
</title>
4685 <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
4688 <variablelist class='network-directives'
>
4689 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4690 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4693 <term><varname>LatencySec=
</varname></term>
4695 <para>Specifies the latency parameter, which specifies the maximum amount of time a
4696 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
4698 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4703 <term><varname>LimitBytes=
</varname></term>
4705 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
4706 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
4707 respectively, to the base of
1024. Defaults to unset.
</para>
4709 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4714 <term><varname>BurstBytes=
</varname></term>
4716 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
4717 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
4718 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to
4721 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4726 <term><varname>Rate=
</varname></term>
4728 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
4729 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
4730 Defaults to unset.
</para>
4732 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4737 <term><varname>MPUBytes=
</varname></term>
4739 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
4740 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
4741 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to zero.
</para>
4743 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4748 <term><varname>PeakRate=
</varname></term>
4750 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
4751 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
4752 1000. Defaults to unset.
</para>
4754 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4759 <term><varname>MTUBytes=
</varname></term>
4761 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
4762 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
4763 Defaults to unset.
</para>
4765 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4772 <title>[PIE] Section Options
</title>
4773 <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
4774 controller-Enhanced (PIE).
</para>
4776 <variablelist class='network-directives'
>
4777 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4778 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4781 <term><varname>PacketLimit=
</varname></term>
4783 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4784 incoming packets are dropped. An unsigned integer in the range
1…
4294967294. Defaults to unset and
4785 kernel's default is used.
</para>
4787 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4794 <title>[FlowQueuePIE] Section Options
</title>
4795 <para>The
<literal>[FlowQueuePIE]
</literal> section manages the queueing discipline
4796 (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).
</para>
4798 <variablelist class='network-directives'
>
4799 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4800 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4803 <term><varname>PacketLimit=
</varname></term>
4805 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4806 incoming packets are dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and
4807 kernel's default is used.
</para>
4809 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4816 <title>[StochasticFairBlue] Section Options
</title>
4817 <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
4820 <variablelist class='network-directives'
>
4821 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4822 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4825 <term><varname>PacketLimit=
</varname></term>
4827 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4828 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
4829 kernel's default is used.
</para>
4831 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4838 <title>[StochasticFairnessQueueing] Section Options
</title>
4839 <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
4840 fairness queueing (sfq).
</para>
4842 <variablelist class='network-directives'
>
4843 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4844 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4847 <term><varname>PerturbPeriodSec=
</varname></term>
4849 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
4851 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4858 <title>[BFIFO] Section Options
</title>
4859 <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
4862 <variablelist class='network-directives'
>
4863 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4864 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4867 <term><varname>LimitBytes=
</varname></term>
4869 <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
4870 in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
4871 reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
4872 as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
4873 kernel default is used.
</para>
4875 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4882 <title>[PFIFO] Section Options
</title>
4883 <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
4886 <variablelist class='network-directives'
>
4887 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4888 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4891 <term><varname>PacketLimit=
</varname></term>
4893 <para>Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents
4894 overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this
4895 limit is reached, incoming packets are dropped. An unsigned integer in the range
4896 0…
4294967294. Defaults to unset and kernel's default is used.
</para>
4898 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4905 <title>[PFIFOHeadDrop] Section Options
</title>
4906 <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
4907 Head Drop (pfifo_head_drop).
</para>
4909 <variablelist class='network-directives'
>
4910 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4911 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4914 <term><varname>PacketLimit=
</varname></term>
4916 <para>As in [PFIFO] section.
</para>
4918 <xi:include href=
"version-info.xml" xpointer=
"v246"/></listitem>
4924 <title>[PFIFOFast] Section Options
</title>
4925 <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
4926 (pfifo_fast).
</para>
4928 <variablelist class='network-directives'
>
4929 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4930 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4935 <title>[CAKE] Section Options
</title>
4936 <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
4939 <variablelist class='network-directives'
>
4940 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4941 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4944 <term><varname>Bandwidth=
</varname></term>
4946 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
4947 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
4948 unset and kernel's default is used.
</para>
4950 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4955 <term><varname>AutoRateIngress=
</varname></term>
4957 <para>Takes a boolean value. Enables automatic capacity estimation based on traffic arriving
4958 at this qdisc. This is most likely to be useful with cellular links, which tend to change
4959 quality randomly. If this setting is enabled, the
<varname>Bandwidth=
</varname> setting is
4960 used as an initial estimate. Defaults to unset, and the kernel's default is used.
</para>
4962 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4967 <term><varname>OverheadBytes=
</varname></term>
4969 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative.
4970 Takes an integer in the range -
64…
256. Defaults to unset and kernel's default is used.
4973 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4978 <term><varname>MPUBytes=
</varname></term>
4980 <para>Rounds each packet (including overhead) up to the specified bytes. Takes an integer in
4981 the range
1…
256. Defaults to unset and kernel's default is used.
</para>
4983 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4988 <term><varname>CompensationMode=
</varname></term>
4990 <para>Takes one of
<literal>none
</literal>,
<literal>atm
</literal>, or
<literal>ptm
</literal>.
4991 Specifies the compensation mode for overhead calculation. When
<literal>none
</literal>, no
4992 compensation is taken into account. When
<literal>atm
</literal>, enables the compensation for
4993 ATM cell framing, which is normally found on ADSL links. When
<literal>ptm
</literal>, enables
4994 the compensation for PTM encoding, which is normally found on VDSL2 links and uses a
64b/
65b
4995 encoding scheme. Defaults to unset and the kernel's default is used.
</para>
4997 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5002 <term><varname>UseRawPacketSize=
</varname></term>
5004 <para>Takes a boolean value. When true, the packet size reported by the Linux kernel will be
5005 used, instead of the underlying IP packet size. Defaults to unset, and the kernel's default
5008 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5013 <term><varname>FlowIsolationMode=
</varname></term>
5015 <para>CAKE places packets from different flows into different queues, then packets from each
5016 queue are delivered fairly. This specifies whether the fairness is based on source address,
5017 destination address, individual flows, or any combination of those. The available values are:
5022 <term><option>none
</option></term>
5024 The flow isolation is disabled, and all traffic passes through a single queue.
5027 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5030 <term><option>src-host
</option></term>
5032 Flows are defined only by source address. Equivalent to the
<literal>srchost
</literal>
5033 option for
<command>tc qdisc
</command> command. See also
5034 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5037 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5040 <term><option>dst-host
</option></term>
5042 Flows are defined only by destination address. Equivalent to the
5043 <literal>dsthost
</literal> option for
<command>tc qdisc
</command> command. See also
5044 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5047 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5050 <term><option>hosts
</option></term>
5052 Flows are defined by source-destination host pairs. Equivalent to the same option for
5053 <command>tc qdisc
</command> command. See also
5054 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5057 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5060 <term><option>flows
</option></term>
5062 Flows are defined by the entire
5-tuple of source address, destination address,
5063 transport protocol, source port and destination port. Equivalent to the same 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>
5071 <term><option>dual-src-host
</option></term>
5073 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
5074 fairness is applied first over source addresses, then over individual flows. Equivalent
5075 to the
<literal>dual-srchost
</literal> option for
<command>tc qdisc
</command> command.
5077 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5080 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5083 <term><option>dual-dst-host
</option></term>
5085 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
5086 fairness is applied first over destination addresses, then over individual flows.
5087 Equivalent to the
<literal>dual-dsthost
</literal> option for
5088 <command>tc qdisc
</command> command. See also
5089 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5092 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5095 <term><option>triple
</option></term>
5097 Flows are defined by the
5-tuple (see
<literal>flows
</literal>), and fairness is
5098 applied over source and destination addresses, and also over individual flows.
5099 Equivalent to the
<literal>triple-isolate
</literal> option for
5100 <command>tc qdisc
</command> command. See also
5101 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5104 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5108 <para>Defaults to unset and the kernel's default is used.
</para>
5110 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5115 <term><varname>NAT=
</varname></term>
5117 <para>Takes a boolean value. When true, CAKE performs a NAT lookup before applying
5118 flow-isolation rules, to determine the true addresses and port numbers of the packet, to
5119 improve fairness between hosts inside the NAT. This has no practical effect when
5120 <varname>FlowIsolationMode=
</varname> is
<literal>none
</literal> or
<literal>flows
</literal>,
5121 or if NAT is performed on a different host. Defaults to unset, and the kernel's default is
5124 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5129 <term><varname>PriorityQueueingPreset=
</varname></term>
5131 <para>CAKE divides traffic into
<literal>tins
</literal>, and each tin has its own independent
5132 set of flow-isolation queues, bandwidth threshold, and priority. This specifies the preset of
5133 tin profiles. The available values are:
</para>
5137 <term><option>besteffort
</option></term>
5139 Disables priority queueing by placing all traffic in one tin.
5142 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5145 <term><option>precedence
</option></term>
5147 Enables priority queueing based on the legacy interpretation of TOS
5148 <literal>Precedence
</literal> field. Use of this preset on the modern Internet is
5152 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5155 <term><option>diffserv8
</option></term>
5157 Enables priority queueing based on the Differentiated Service
5158 (
<literal>DiffServ
</literal>) field with eight tins: Background Traffic, High
5159 Throughput, Best Effort, Video Streaming, Low Latency Transactions, Interactive Shell,
5160 Minimum Latency, and Network Control.
5163 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5166 <term><option>diffserv4
</option></term>
5168 Enables priority queueing based on the Differentiated Service
5169 (
<literal>DiffServ
</literal>) field with four tins: Background Traffic, Best Effort,
5170 Streaming Media, and Latency Sensitive.
5173 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5176 <term><option>diffserv3
</option></term>
5178 Enables priority queueing based on the Differentiated Service
5179 (
<literal>DiffServ
</literal>) field with three tins: Background Traffic, Best Effort,
5180 and Latency Sensitive.
5183 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5187 <para>Defaults to unset, and the kernel's default is used.
</para>
5189 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5194 <term><varname>FirewallMark=
</varname></term>
5196 <para>Takes an integer in the range
1…
4294967295. When specified, firewall-mark-based
5197 overriding of CAKE's tin selection is enabled. Defaults to unset, and the kernel's default is
5200 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5205 <term><varname>Wash=
</varname></term>
5207 <para>Takes a boolean value. When true, CAKE clears the DSCP fields, except for ECN bits, of
5208 any packet passing through CAKE. Defaults to unset, and the kernel's default is used.
</para>
5210 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5215 <term><varname>SplitGSO=
</varname></term>
5217 <para>Takes a boolean value. When true, CAKE will split General Segmentation Offload (GSO)
5218 super-packets into their on-the-wire components and dequeue them individually. Defaults to
5219 unset, and the kernel's default is used.
</para>
5221 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5226 <term><varname>RTTSec=
</varname></term>
5228 <para>Specifies the RTT for the filter. Takes a timespan. Typical values are e.g.
100us for
5229 extremely high-performance
10GigE+ networks like datacentre,
1ms for non-WiFi LAN connections,
5230 100ms for typical internet connections. Defaults to unset, and the kernel's default will be used.
5233 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
5238 <term><varname>AckFilter=
</varname></term>
5240 <para>Takes a boolean value, or special value
<literal>aggressive
</literal>. If enabled, ACKs in
5241 each flow are queued and redundant ACKs to the upstream are dropped. If yes, the filter will always
5242 keep at least two redundant ACKs in the queue, while in
<literal>aggressive
</literal> mode, it will
5243 filter down to a single ACK. This may improve download throughput on links with very asymmetrical
5244 rate limits. Defaults to unset, and the kernel's default will be used.
</para>
5246 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
5254 <title>[ControlledDelay] Section Options
</title>
5255 <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
5256 controlled delay (CoDel).
</para>
5258 <variablelist class='network-directives'
>
5259 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5260 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5263 <term><varname>PacketLimit=
</varname></term>
5265 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
5266 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
5267 kernel's default is used.
</para>
5269 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5274 <term><varname>TargetSec=
</varname></term>
5276 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
5277 Defaults to unset and kernel's default is used.
</para>
5279 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5284 <term><varname>IntervalSec=
</varname></term>
5286 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
5287 become too stale. Defaults to unset and kernel's default is used.
</para>
5289 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5294 <term><varname>ECN=
</varname></term>
5296 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
5297 unset and kernel's default is used.
</para>
5299 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5304 <term><varname>CEThresholdSec=
</varname></term>
5306 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5307 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5309 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5316 <title>[DeficitRoundRobinScheduler] Section Options
</title>
5317 <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
5318 Robin Scheduler (DRR).
</para>
5320 <variablelist class='network-directives'
>
5321 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5322 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5327 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
5328 <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
5329 Robin Scheduler (DRR).
</para>
5331 <variablelist class='network-directives'
>
5332 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5333 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5336 <term><varname>QuantumBytes=
</varname></term>
5338 <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
5339 to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5340 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to the MTU of the
5343 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5351 <title>[EnhancedTransmissionSelection] Section Options
</title>
5352 <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
5353 Transmission Selection (ETS).
</para>
5355 <variablelist class='network-directives'
>
5356 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5357 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5360 <term><varname>Bands=
</varname></term>
5362 <para>Specifies the number of bands. An unsigned integer in the range
1…
16. This value has to be at
5363 least large enough to cover the strict bands specified through the
<varname>StrictBands=
</varname>
5364 and bandwidth-sharing bands specified in
<varname>QuantumBytes=
</varname>.
</para>
5366 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5371 <term><varname>StrictBands=
</varname></term>
5373 <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
5374 the range
1…
16.
</para>
5376 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5381 <term><varname>QuantumBytes=
</varname></term>
5383 <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
5384 suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5385 respectively, to the base of
1024. This setting can be specified multiple times. If an empty
5386 string is assigned, then the all previous assignments are cleared.
</para>
5388 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5393 <term><varname>PriorityMap=
</varname></term>
5395 <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
5396 separated list of numbers. The first number indicates which band the packets with priority
0 should
5397 be put to, the second is for priority
1, and so on. There can be up to
16 numbers in the list. If
5398 there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
5399 the last one. Each band number must be in the range
0…
255. This setting can be specified multiple
5400 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
5402 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5409 <title>[GenericRandomEarlyDetection] Section Options
</title>
5410 <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
5411 Early Detection (GRED).
</para>
5413 <variablelist class='network-directives'
>
5414 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5415 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5418 <term><varname>VirtualQueues=
</varname></term>
5420 <para>Specifies the number of virtual queues. Takes an integer in the range
1…
16. Defaults to unset
5421 and kernel's default is used.
</para>
5423 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5428 <term><varname>DefaultVirtualQueue=
</varname></term>
5430 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
5431 Defaults to unset and kernel's default is used.
</para>
5433 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5438 <term><varname>GenericRIO=
</varname></term>
5440 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
5441 unset and kernel's default is used.
</para>
5443 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5450 <title>[FairQueueingControlledDelay] Section Options
</title>
5451 <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
5452 controlled delay (FQ-CoDel).
</para>
5454 <variablelist class='network-directives'
>
5455 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5456 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5459 <term><varname>PacketLimit=
</varname></term>
5461 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
5462 dropped. Defaults to unset and kernel's default is used.
</para>
5464 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5469 <term><varname>MemoryLimitBytes=
</varname></term>
5471 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
5472 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5473 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
5475 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5480 <term><varname>Flows=
</varname></term>
5482 <para>Specifies the number of flows into which the incoming packets are classified.
5483 Defaults to unset and kernel's default is used.
</para>
5485 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5490 <term><varname>TargetSec=
</varname></term>
5492 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
5493 Defaults to unset and kernel's default is used.
</para>
5495 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5500 <term><varname>IntervalSec=
</varname></term>
5502 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
5503 become too stale. Defaults to unset and kernel's default is used.
</para>
5505 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5510 <term><varname>QuantumBytes=
</varname></term>
5512 <para>Specifies the number of bytes used as the
"deficit" in the fair queuing algorithm timespan.
5513 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5514 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
5516 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5521 <term><varname>ECN=
</varname></term>
5523 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
5524 unset and kernel's default is used.
</para>
5526 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5531 <term><varname>CEThresholdSec=
</varname></term>
5533 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5534 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5536 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5543 <title>[FairQueueing] Section Options
</title>
5544 <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
5547 <variablelist class='network-directives'
>
5548 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5549 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5552 <term><varname>PacketLimit=
</varname></term>
5554 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
5555 dropped. Defaults to unset and kernel's default is used.
</para>
5557 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5562 <term><varname>FlowLimit=
</varname></term>
5564 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
5565 unset and kernel's default is used.
</para>
5567 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5572 <term><varname>QuantumBytes=
</varname></term>
5574 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
5575 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5576 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
5577 default is used.
</para>
5579 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5584 <term><varname>InitialQuantumBytes=
</varname></term>
5586 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
5587 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
5588 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
5589 kernel's default is used.
</para>
5591 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5596 <term><varname>MaximumRate=
</varname></term>
5598 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
5599 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
5600 1000. Defaults to unset and kernel's default is used.
</para>
5602 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5607 <term><varname>Buckets=
</varname></term>
5609 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
5610 kernel's default is used.
</para>
5612 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5617 <term><varname>OrphanMask=
</varname></term>
5619 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
5620 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
5621 kernel's default is used.
</para>
5623 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5628 <term><varname>Pacing=
</varname></term>
5630 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
5631 default is used.
</para>
5633 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5638 <term><varname>CEThresholdSec=
</varname></term>
5640 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5641 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5643 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5650 <title>[TrivialLinkEqualizer] Section Options
</title>
5651 <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
5652 equalizer (teql).
</para>
5654 <variablelist class='network-directives'
>
5655 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5656 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5659 <term><varname>Id=
</varname></term>
5661 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
5662 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
5663 <constant>max_equalizers=N+
1</constant> option must be loaded before
5664 <command>systemd-networkd
</command> is started.
</para>
5666 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5673 <title>[HierarchyTokenBucket] Section Options
</title>
5674 <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
5675 bucket (htb).
</para>
5677 <variablelist class='network-directives'
>
5678 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5679 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5682 <term><varname>DefaultClass=
</varname></term>
5684 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
5685 to the class. Defaults to unset.
</para>
5687 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5692 <term><varname>RateToQuantum=
</varname></term>
5694 <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
5695 configured in
<varname>Rate=
</varname> by
<varname>RateToQuantum=
</varname>.
</para>
5697 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5704 <title>[HierarchyTokenBucketClass] Section Options
</title>
5705 <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
5708 <variablelist class='network-directives'
>
5709 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5710 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5713 <term><varname>Priority=
</varname></term>
5715 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
5716 priority field are tried for packets first.
</para>
5718 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5723 <term><varname>QuantumBytes=
</varname></term>
5725 <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
5726 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
5729 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5734 <term><varname>MTUBytes=
</varname></term>
5736 <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
5737 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
5739 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5744 <term><varname>OverheadBytes=
</varname></term>
5746 <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
5747 computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5748 Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
5750 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5755 <term><varname>Rate=
</varname></term>
5757 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
5758 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
5759 to the base of
1000. This setting is mandatory.
</para>
5761 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5766 <term><varname>CeilRate=
</varname></term>
5768 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
5769 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
5770 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
5773 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5778 <term><varname>BufferBytes=
</varname></term>
5780 <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
5781 with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
5782 to the base of
1024.
</para>
5784 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5789 <term><varname>CeilBufferBytes=
</varname></term>
5791 <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
5792 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5793 respectively, to the base of
1024.
</para>
5795 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5802 <title>[HeavyHitterFilter] Section Options
</title>
5803 <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
5806 <variablelist class='network-directives'
>
5807 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5808 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5811 <term><varname>PacketLimit=
</varname></term>
5813 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
5814 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
5815 kernel's default is used.
</para>
5817 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5824 <title>[QuickFairQueueing] Section Options
</title>
5825 <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
5828 <variablelist class='network-directives'
>
5829 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5830 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5835 <title>[QuickFairQueueingClass] Section Options
</title>
5836 <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
5839 <variablelist class='network-directives'
>
5840 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5841 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5844 <term><varname>Weight=
</varname></term>
5846 <para>Specifies the weight of the class. Takes an integer in the range
1…
1023. Defaults to
5847 unset in which case the kernel default is used.
</para>
5849 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5854 <term><varname>MaxPacketBytes=
</varname></term>
5856 <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the
5857 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
5858 1024. When unset, the kernel default is used.
</para>
5860 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5867 <title>[BridgeVLAN] Section Options
</title>
5869 The [BridgeVLAN] section manages the VLAN ID configurations of a bridge master or port, and accepts the
5870 following keys. To make the settings in this section take an effect,
5871 <varname>VLANFiltering=
</varname> option has to be enabled on the bridge master, see the [Bridge]
5873 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
5874 If at least one valid settings specified in this section in a .network file for an interface, all
5875 assigned VLAN IDs on the interface that are not configured in the .network file will be removed. If
5876 VLAN IDs on an interface need to be managed by other tools, then the settings in this section cannot
5877 be used in the matching .network file.
5880 <variablelist class='network-directives'
>
5882 <term><varname>VLAN=
</varname></term>
5884 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. Takes an
5885 integer in the range
1…
4094. This setting can be specified multiple times. If an empty string is
5886 assigned, then the all previous assignments are cleared.
</para>
5888 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5892 <term><varname>EgressUntagged=
</varname></term>
5894 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
5895 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will
5896 enable the VLAN ID for ingress as well. This can be either a single ID or a range M-N. This
5897 setting can be specified multiple times. If an empty string is assigned, then the all previous
5898 assignments are cleared.
</para>
5900 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5904 <term><varname>PVID=
</varname></term>
5906 <para>The port VLAN ID specified here is assigned to all untagged frames at ingress. Takes an
5907 VLAN ID or negative boolean value (e.g.
<literal>no
</literal>). When false, the currently
5908 assigned port VLAN ID will be dropped. Configuring
<varname>PVID=
</varname> implicates the use of
5909 <varname>VLAN=
</varname> setting in the above and will enable the VLAN ID for ingress as well.
5910 Defaults to unset, and will keep the assigned port VLAN ID if exists.
</para>
5912 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5919 <title>Examples
</title>
5921 <title>Static network configuration
</title>
5923 <programlisting># /etc/systemd/network/
50-static.network
5928 Address=
192.168.0.15/
24
5929 Gateway=
192.168.0.1</programlisting>
5931 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
5932 specified gateway will be used for a default route.
</para>
5936 <title>DHCP on ethernet links
</title>
5938 <programlisting># /etc/systemd/network/
80-dhcp.network
5943 DHCP=yes
</programlisting>
5945 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
5946 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
5950 <title>IPv6 Prefix Delegation (DHCPv6 PD)
</title>
5952 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-upstream.network
5959 # The below setting is optional, to also assign an address in the delegated prefix
5960 # to the upstream interface. If not necessary, then comment out the line below and
5961 # the [DHCPPrefixDelegation] section.
5962 DHCPPrefixDelegation=yes
5964 # If the upstream network provides Router Advertisement with Managed bit set,
5965 # then comment out the line below and WithoutRA= setting in the [DHCPv6] section.
5971 [DHCPPrefixDelegation]
5972 UplinkInterface=:self
5974 Announce=no
</programlisting>
5976 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-downstream.network
5981 DHCPPrefixDelegation=yes
5984 # It is expected that the host is acting as a router. So, usually it is not
5985 # necessary to receive Router Advertisement from other hosts in the downstream network.
5988 [DHCPPrefixDelegation]
5989 UplinkInterface=enp1s0
5991 Announce=yes
</programlisting>
5993 <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
5994 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
5995 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
6000 <title>IPv6 Prefix Delegation (DHCPv4
6RD)
</title>
6002 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-upstream.network
6009 # When DHCPv4-
6RD is used, the upstream network does not support IPv6.
6010 # Hence, it is not necessary to wait for Router Advertisement, which is enabled by default.
6014 Use6RD=yes
</programlisting>
6016 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-downstream.network
6021 DHCPPrefixDelegation=yes
6024 # It is expected that the host is acting as a router. So, usually it is not
6025 # necessary to receive Router Advertisement from other hosts in the downstream network.
6028 [DHCPPrefixDelegation]
6029 UplinkInterface=enp1s0
6031 Announce=yes
</programlisting>
6033 <para>This will enable DHCPv4-
6RD on the interface enp1s0 as an upstream interface where the
6034 DHCPv4 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
6035 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
6040 <title>A bridge with two enslaved links
</title>
6042 <programlisting># /etc/systemd/network/
25-bridge-static.netdev
6045 Kind=bridge
</programlisting>
6047 <programlisting># /etc/systemd/network/
25-bridge-static.network
6052 Address=
192.168.0.15/
24
6054 DNS=
192.168.0.1</programlisting>
6056 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
6061 Bridge=bridge0
</programlisting>
6063 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
6068 Bridge=bridge0
</programlisting>
6070 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
6071 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
6072 and network assigned, and a default route via the specified gateway will be
6073 added. The specified DNS server will be added to the global list of DNS resolvers.
6078 <title>Bridge port with VLAN forwarding
</title>
6081 # /etc/systemd/network/
25-bridge-slave-interface-
1.network
6097 EgressUntagged=
300-
400</programlisting>
6099 <para>This overrides the configuration specified in the previous example for the
6100 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
6101 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
6102 untagged when they leave on this interface. Untagged packets which arrive on this
6103 interface will be assigned VLAN ID
42.
</para>
6107 <title>Various tunnels
</title>
6109 <programlisting>/etc/systemd/network/
25-tunnels.network
6120 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
6126 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
6132 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
6138 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
6144 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
6145 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
6149 <title>A bond device
</title>
6151 <programlisting># /etc/systemd/network/
30-bond1.network
6159 <programlisting># /etc/systemd/network/
30-bond1.netdev
6165 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
6167 MACAddress=
52:
54:
00:e9:
64:
41
6173 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
6175 MACAddress=
52:
54:
00:e9:
64:
42
6181 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
6182 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
6183 will be used to acquire an address.
</para>
6187 <title>Virtual Routing and Forwarding (VRF)
</title>
6188 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
6189 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
6190 within the routing table defined during VRF creation. For kernels before
4.8 traffic
6191 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
6193 <programlisting># /etc/systemd/network/
25-vrf.network
6203 <title>MacVTap
</title>
6204 <para>This brings up a network interface
<literal>macvtap-test
</literal>
6205 and attaches it to
<literal>enp0s25
</literal>.
</para>
6206 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
6211 MACVTAP=macvtap-test
6216 <title>A Xfrm interface with physical underlying device.
</title>
6218 <programlisting># /etc/systemd/network/
27-xfrm.netdev
6224 InterfaceId=
7</programlisting>
6226 <programlisting># /etc/systemd/network/
27-eth0.network
6231 Xfrm=xfrm0
</programlisting>
6233 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
6234 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
6235 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
6241 <title>See Also
</title>
6243 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
6244 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
6245 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
6246 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
6247 <citerefentry><refentrytitle>systemd-network-generator.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
6248 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>