2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/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, a minimum operational state (e.g.,
<literal>carrier
</literal>), or a range
263 of operational state separated with a colon (e.g.,
<literal>degraded:routable
</literal>).
265 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
266 for possible operational states. When
<literal>yes
</literal>, the network is deemed required
267 when determining whether the system is online (including when running
268 <command>systemd-networkd-wait-online
</command>). When
<literal>no
</literal>, the network is
269 ignored when determining the online state. When a minimum operational state and an optional
270 maximum operational state are set,
<command>systemd-networkd-wait-online
</command> deems that the
271 interface is online when the operational state is in the specified range.
</para>
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 <para>The boolean value
<literal>yes
</literal> is translated as follows;
289 <term><option>CAN devices
</option></term>
291 <para><literal>carrier
</literal>,
</para>
292 <xi:include href=
"version-info.xml" xpointer=
"v256"/>
296 <term><option>Master devices, e.g. bond or bridge
</option></term>
298 <para><literal>degraded-carrier
</literal> with
<varname>RequiredFamilyForOnline=any
</varname>,
</para>
299 <xi:include href=
"version-info.xml" xpointer=
"v256"/>
303 <term><option>Bonding port interfaces
</option></term>
305 <para><literal>enslaved
</literal>,
</para>
306 <xi:include href=
"version-info.xml" xpointer=
"v256"/>
310 <term><option>Other interfaces
</option></term>
312 <para><literal>degraded
</literal>.
</para>
313 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
319 <para>This setting can be overridden by the command line option for
320 <command>systemd-networkd-wait-online
</command>. See
321 <citerefentry><refentrytitle>systemd-networkd-wait-online.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
322 for more details.
</para>
324 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
329 <term><varname>RequiredFamilyForOnline=
</varname></term>
331 <para>Takes an address family. When specified, an IP address in the given family is deemed
332 required when determining whether the link is online (including when running
333 <command>systemd-networkd-wait-online
</command>). Takes one of
<literal>ipv4
</literal>,
334 <literal>ipv6
</literal>,
<literal>both
</literal>, or
<literal>any
</literal>. Defaults to
335 <literal>no
</literal>. Note that this option has no effect if
336 <literal>RequiredForOnline=no
</literal>.
</para>
338 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
343 <term><varname>ActivationPolicy=
</varname></term>
345 <para>Specifies the policy for
<command>systemd-networkd
</command> managing the link
346 administrative state. Specifically, this controls how
<command>systemd-networkd
</command>
347 changes the network device's
<literal>IFF_UP
</literal> flag, which is sometimes
348 controlled by system administrators by running e.g.,
349 <command>ip link set dev eth0 up
</command> or
<command>ip link set dev eth0 down
</command>,
350 and can also be changed with
<command>networkctl up eth0
</command> or
351 <command>networkctl down eth0
</command>.
</para>
353 <para>Takes one of
<literal>up
</literal>,
<literal>always-up
</literal>,
354 <literal>manual
</literal>,
<literal>always-down
</literal>,
<literal>down
</literal>,
355 or
<literal>bound
</literal>. When
<literal>manual
</literal>,
356 <command>systemd-networkd
</command> will not change the link's admin state automatically;
357 the system administrator must bring the interface up or down manually, as desired. When
358 <literal>up
</literal> (the default) or
<literal>always-up
</literal>, or
359 <literal>down
</literal> or
<literal>always-down
</literal>,
360 <command>systemd-networkd
</command> will set the link up or down, respectively, when the
361 interface is (re)configured. When
<literal>always-up
</literal> or
362 <literal>always-down
</literal>,
<command>systemd-networkd
</command> will set the link up or
363 down, respectively, any time
<command>systemd-networkd
</command> detects a change in the
364 administrative state. When
<varname>BindCarrier=
</varname> is also set, this is automatically
365 set to
<literal>bound
</literal> and any other value is ignored.
</para>
367 <para>When the policy is set to
<literal>down
</literal> or
<literal>manual
</literal>, the
368 default value of
<varname>RequiredForOnline=
</varname> is
<literal>no
</literal>. When the
369 policy is set to
<literal>always-down
</literal>, the value of
370 <varname>RequiredForOnline=
</varname> forced to
<literal>no
</literal>.
</para>
372 <para>The administrative state is not the same as the carrier state, so using
373 <literal>always-up
</literal> does not mean the link will never lose carrier. The link carrier
374 depends on both the administrative state as well as the network device's physical connection.
375 However, to avoid reconfiguration failures, when using
<literal>always-up
</literal>,
376 <varname>IgnoreCarrierLoss=
</varname> is forced to true.
</para>
378 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
384 <xi:include href=
"systemd.link.xml" xpointer=
"sr-iov" />
387 <title>[Network] Section Options
</title>
389 <para>The [Network] section accepts the following keys:
</para>
391 <variablelist class='network-directives'
>
393 <term><varname>Description=
</varname></term>
395 <para>A description of the device. This is only used for presentation purposes.
</para>
397 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
402 <term><varname>DHCP=
</varname></term>
404 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
<literal>yes
</literal>,
405 <literal>no
</literal>,
<literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults to
406 <literal>no
</literal>.
</para>
408 <para>Note that DHCPv6 will by default be triggered by Router Advertisements, if reception is
409 enabled, regardless of this parameter. By explicitly enabling DHCPv6 support here, the DHCPv6
410 client will be started in the mode specified by the
<varname>WithoutRA=
</varname> setting in the
411 [DHCPv6] section, regardless of the presence of routers on the link, or what flags the routers
412 pass. See
<varname>IPv6AcceptRA=
</varname>.
</para>
414 <para>Furthermore, note that by default the domain name specified through DHCP is not used
415 for name resolution. See option
<option>UseDomains=
</option> below.
</para>
417 <para>See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the
418 DHCP client support.
</para>
420 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
425 <term><varname>DHCPServer=
</varname></term>
427 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started.
428 Defaults to
<literal>no
</literal>. Further settings for the DHCP server may be set in the
429 [DHCPServer] section described below.
</para>
431 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
436 <term><varname>LinkLocalAddressing=
</varname></term>
438 <para>Enables link-local address autoconfiguration. Accepts
<option>yes
</option>,
439 <option>no
</option>,
<option>ipv4
</option>, and
<option>ipv6
</option>. An IPv6 link-local
440 address is configured when
<option>yes
</option> or
<option>ipv6
</option>. An IPv4 link-local
441 address is configured when
<option>yes
</option> or
<option>ipv4
</option> and when DHCPv4
442 autoconfiguration has been unsuccessful for some time. (IPv4 link-local address
443 autoconfiguration will usually happen in parallel with repeated attempts to acquire a DHCPv4
446 <para>Defaults to
<option>no
</option> when
<varname>KeepMaster=
</varname> or
447 <varname>Bridge=
</varname> is set or when the specified
448 <varname>MACVLAN=
</varname>/
<varname>MACVTAP=
</varname> has
<varname>Mode=passthru
</varname>,
449 or
<option>ipv6
</option> otherwise.
</para>
451 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
456 <term><varname>IPv6LinkLocalAddressGenerationMode=
</varname></term>
458 <para>Specifies how IPv6 link-local address is generated. Takes one of
459 <literal>eui64
</literal>,
<literal>none
</literal>,
<literal>stable-privacy
</literal> and
460 <literal>random
</literal>. When unset,
<literal>stable-privacy
</literal> is used if
461 <varname>IPv6StableSecretAddress=
</varname> is specified, and if not,
462 <literal>eui64
</literal> is used. Note that if
<varname>LinkLocalAddressing=
</varname> is
463 <literal>no
</literal> or
<literal>ipv4
</literal>, then
464 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> will be ignored. Also, even if
465 <varname>LinkLocalAddressing=
</varname> is
<literal>yes
</literal> or
<literal>ipv6
</literal>,
466 setting
<varname>IPv6LinkLocalAddressGenerationMode=none
</varname>
467 disables to configure an IPv6 link-local address.
</para>
469 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
474 <term><varname>IPv6StableSecretAddress=
</varname></term>
476 <para>Takes an IPv6 address. The specified address will be used as a stable secret for
477 generating IPv6 link-local address. If this setting is specified, and
478 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> is unset, then
479 <varname>IPv6LinkLocalAddressGenerationMode=stable-privacy
</varname> is implied.
480 If this setting is not specified, and
<literal>stable-privacy
</literal> is set to
481 <varname>IPv6LinkLocalAddressGenerationMode=
</varname>,
482 then a stable secret address will be generated from the local machine ID and the interface
485 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
490 <term><varname>IPv4LLStartAddress=
</varname></term>
492 <para>Specifies the first IPv4 link-local address to try. Takes an IPv4 address for example
493 169.254.1.2, from the link-local address range:
169.254.0.0/
16 except for
169.254.0.0/
24 and
494 169.254.255.0/
24. This setting may be useful if the device should always have the same address
495 as long as there is no address conflict. When unset, a random address will be automatically
496 selected. Defaults to unset.
</para>
498 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
503 <term><varname>IPv4LLRoute=
</varname></term>
505 <para>Takes a boolean. If set to true, sets up the route needed for non-IPv4LL hosts to
506 communicate with IPv4LL-only hosts. Defaults to false.
</para>
508 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
513 <term><varname>DefaultRouteOnDevice=
</varname></term>
515 <para>Takes a boolean. If set to true, sets up the IPv4 default route bound to the interface.
516 Defaults to false. This is useful when creating routes on point-to-point interfaces. This is
517 equivalent to e.g. the following,
518 <programlisting>ip route add default dev veth99
</programlisting>
520 <programlisting>[Route]
521 Gateway=
0.0.0.0</programlisting></para>
522 <para>Currently, there are no way to specify e.g., the table for the route configured by this
523 setting. To configure the default route with such an additional property, please use the
525 <programlisting>[Route]
527 Table=
1234</programlisting></para>
528 <para>If you'd like to create an IPv6 default route bound to the interface, please use the
530 <programlisting>[Route]
532 Table=
1234</programlisting></para>
534 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
539 <term><varname>LLMNR=
</varname></term>
541 <para>Takes a boolean or
<literal>resolve
</literal>. When true, enables
542 <ulink url=
"https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution
</ulink>
543 on the link. When set to
<literal>resolve
</literal>, only resolution is enabled, but not host
544 registration and announcement. Defaults to true. This setting is read by
545 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
548 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
553 <term><varname>MulticastDNS=
</varname></term>
555 <para>Takes a boolean or
<literal>resolve
</literal>. When true, enables
556 <ulink url=
"https://tools.ietf.org/html/rfc6762">Multicast DNS
</ulink> support on the link.
557 When set to
<literal>resolve
</literal>, only resolution is enabled, but not host or service
558 registration and announcement. Defaults to false. This setting is read by
559 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
562 <xi:include href=
"version-info.xml" xpointer=
"v229"/>
567 <term><varname>DNSOverTLS=
</varname></term>
569 <para>Takes a boolean or
<literal>opportunistic
</literal>. When true, enables
570 <ulink url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink> support on the link.
571 When set to
<literal>opportunistic
</literal>, compatibility with non-DNS-over-TLS servers is
572 increased, by automatically turning off DNS-over-TLS servers in this case. This option
573 defines a per-interface setting for
574 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
575 global
<varname>DNSOverTLS=
</varname> option. Defaults to unset, and the global setting will
576 be used. This setting is read by
577 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
580 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
585 <term><varname>DNSSEC=
</varname></term>
587 <para>Takes a boolean or
<literal>allow-downgrade
</literal>. When true, enables
588 <ulink url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink> DNS validation support on the
589 link. When set to
<literal>allow-downgrade
</literal>, compatibility with non-DNSSEC capable
590 networks is increased, by automatically turning off DNSSEC in this case. This option defines
591 a per-interface setting for
592 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
593 global
<varname>DNSSEC=
</varname> option. Defaults to unset, and the global setting will be
594 used. This setting is read by
595 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
598 <xi:include href=
"version-info.xml" xpointer=
"v229"/>
603 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
605 <para>A space-separated list of DNSSEC negative trust anchor domains. If specified and DNSSEC
606 is enabled, look-ups done via the interface's DNS server will be subject to the list of
607 negative trust anchors, and not require authentication for the specified domains, or anything
608 below it. Use this to disable DNSSEC authentication for specific private domains, that cannot
609 be proven valid using the Internet DNS hierarchy. Defaults to the empty list. This setting is
611 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
614 <xi:include href=
"version-info.xml" xpointer=
"v229"/>
619 <term><varname>LLDP=
</varname></term>
621 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol
622 commonly implemented on professional routers and bridges which announces which physical port
623 a system is connected to, as well as other related data. Accepts a boolean or the special
624 value
<literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a
625 database of all LLDP neighbors maintained. If
<literal>routers-only
</literal> is set only
626 LLDP data of various types of routers is collected and LLDP data about other types of devices
627 ignored (such as stations, telephones and others). If false, LLDP reception is disabled.
628 Defaults to
<literal>routers-only
</literal>. Use
629 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
630 to query the collected neighbor data. LLDP is only available on Ethernet links. See
631 <varname>EmitLLDP=
</varname> below for enabling LLDP packet emission from the local system.
634 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
639 <term><varname>EmitLLDP=
</varname></term>
641 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the
642 special values
<literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
643 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission.
644 If not false, a short LLDP packet with information about the local system is sent out in
645 regular intervals on the link. The LLDP packet will contain information about the local
646 hostname, the local machine ID (as stored in
647 <citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
648 and the local interface name, as well as the pretty hostname of the system (as set in
649 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
650 LLDP emission is only available on Ethernet links. Note that this setting passes data
651 suitable for identification of host to the network and should thus not be enabled on
652 untrusted networks, where such identification data should not be made available. Use this
653 option to permit other systems to identify on which interfaces they are connected to this
654 system. The three special values control propagation of the LLDP packets. The
655 <literal>nearest-bridge
</literal> setting permits propagation only to the nearest connected
656 bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays,
657 but not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until
658 a customer bridge is reached. For details about these concepts, see
659 <ulink url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>.
660 Note that configuring this setting to true is equivalent to
661 <literal>nearest-bridge
</literal>, the recommended and most restricted level of propagation.
662 See
<varname>LLDP=
</varname> above for an option to enable LLDP reception.
</para>
664 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
669 <term><varname>BindCarrier=
</varname></term>
671 <para>A link name or a list of link names. When set, controls the behavior of the current
672 link. When all links in the list are in an operational down state, the current link is
673 brought down. When at least one link has carrier, the current interface is brought up.
</para>
675 <para>This forces
<varname>ActivationPolicy=
</varname> to be set to
<literal>bound
</literal>.
678 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
683 <term><varname>Address=
</varname></term>
685 <para>A static IPv4 or IPv6 address and its prefix length, separated by a
686 <literal>/
</literal> character. Specify this key more than once to configure several
687 addresses. The format of the address must be as described in
688 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
689 This is a short-hand for an [Address] section only containing an Address key (see below).
690 This option may be specified more than once.
</para>
692 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
693 <literal>::
</literal> (for IPv6), a new address range of the requested size is automatically
694 allocated from a system-wide pool of unused ranges. Note that the prefix length must be equal
695 or larger than
8 for IPv4, and
64 for IPv6. The allocated range is checked against all
696 current network interfaces and all known network configuration files to avoid address range
697 conflicts. The default system-wide pool consists of
192.168.0.0/
16,
172.16.0.0/
12 and
698 10.0.0.0/
8 for IPv4, and fd00::/
8 for IPv6. This functionality is useful to manage a large
699 number of dynamically created network interfaces with the same network configuration and
700 automatic address range assignment.
</para>
702 <para>If an empty string is specified, then the all previous assignments in both [Network] and
703 [Address] sections are cleared.
</para>
705 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
710 <term><varname>Gateway=
</varname></term>
712 <para>The gateway address, which must be in the format described in
713 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
714 This is a short-hand for a [Route] section only containing a
<varname>Gateway=
</varname> key.
715 This option may be specified more than once.
</para>
717 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
722 <term><varname>DNS=
</varname></term>
724 <para>A DNS server address, which must be in the format described in
725 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
726 This option may be specified more than once. Each address can optionally take a port number
727 separated with
<literal>:
</literal>, a network interface name or index separated with
728 <literal>%
</literal>, and a Server Name Indication (SNI) separated with
<literal>#
</literal>.
729 When IPv6 address is specified with a port number, then the address must be in the square
730 brackets. That is, the acceptable full formats are
731 <literal>111.222.333.444:
9953%ifname#example.com
</literal> for IPv4 and
732 <literal>[
1111:
2222::
3333]:
9953%ifname#example.com
</literal> for IPv6. If an empty string is
733 assigned, then the all previous assignments are cleared. This setting is read by
734 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
737 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
742 <term><varname>Domains=
</varname></term>
744 <para>A whitespace-separated list of domains which should be resolved using the DNS servers
745 on this link. Each item in the list should be a domain name, optionally prefixed with a tilde
746 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
747 domains without the prefix are called
"search domains" and are first used as search suffixes
748 for extending single-label hostnames (hostnames containing no dots) to become fully qualified
749 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
750 specified search domains are appended to it in turn, converting it into a fully qualified
751 domain name, until one of them may be successfully resolved.
</para>
753 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups
754 for hostnames ending in those domains (hence also single label names, if any
"search domains"
755 are listed), are routed to the DNS servers configured for this interface. The domain routing
756 logic is particularly useful on multi-homed hosts with DNS servers serving particular private
757 DNS zones on each interface.
</para>
759 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a
760 routing domain, the dot referring to the DNS root domain which is the implied suffix of all
761 valid DNS names) has special effect. It causes all DNS traffic which does not match another
762 configured domain routing entry to be routed to DNS servers specified for this interface.
763 This setting is useful to prefer a certain set of DNS servers if a link on which they are
764 connected is available.
</para>
766 <para>This setting is read by
767 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
768 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname>
770 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
771 Domain name routing has no equivalent in the traditional glibc API, which has no concept of
772 domain name servers limited to a specific link.
</para>
774 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
779 <term><varname>DNSDefaultRoute=
</varname></term>
781 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for
782 resolving domain names that do not match any link's configured
<varname>Domains=
</varname>
783 setting. If false, this link's configured DNS servers are never used for such domains, and
784 are exclusively used for resolving names that match at least one of the domains configured on
785 this link. If not specified defaults to an automatic mode: queries not matching any link's
786 configured domains will be routed to this link if it has no routing-only domains configured.
789 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
794 <term><varname>NTP=
</varname></term>
796 <para>An NTP server address (either an IP address, or a hostname). This option may be
797 specified more than once. This setting is read by
798 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
801 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
806 <term><varname>IPForward=
</varname></term>
808 <para>Configures IP packet forwarding for the system. If enabled, incoming packets on any
809 network interface will be forwarded to any other interfaces according to the routing table.
810 Takes a boolean, or the values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>, which only
811 enable IP packet forwarding for the specified address family. This controls the
812 <filename>net.ipv4.ip_forward
</filename> and
<filename>net.ipv6.conf.all.forwarding
</filename>
813 sysctl options of the network interface (see
814 <ulink url=
"https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl
</ulink>
815 for details about sysctl options). Defaults to
<literal>no
</literal>.
</para>
817 <para>Note: this setting controls a global kernel option, and does so one way only: if a
818 network that has this setting enabled is set up the global setting is turned on. However,
819 it is never turned off again, even after all networks with this setting enabled are shut
822 <para>To allow IP packet forwarding only between specific network interfaces use a firewall.
825 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
830 <term><varname>IPMasquerade=
</varname></term>
832 <para>Configures IP masquerading for the network interface. If enabled, packets forwarded
833 from the network interface will be appear as coming from the local host. Takes one of
834 <literal>ipv4
</literal>,
<literal>ipv6
</literal>,
<literal>both
</literal>, or
835 <literal>no
</literal>. Defaults to
<literal>no
</literal>. If enabled, this automatically sets
836 <varname>IPForward=
</varname> to one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal> or
837 <literal>yes
</literal>.
</para>
838 <para>Note. Any positive boolean values such as
<literal>yes
</literal> or
839 <literal>true
</literal> are now deprecated. Please use one of the values in the above.
</para>
841 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
846 <term><varname>IPv6PrivacyExtensions=
</varname></term>
848 <para>Configures use of stateless temporary addresses that change over time (see
849 <ulink url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
850 Privacy Extensions for Stateless Address Autoconfiguration in IPv6). Takes a boolean or the
851 special values
<literal>prefer-public
</literal> and
<literal>kernel
</literal>. When true,
852 enables the privacy extensions and prefers temporary addresses over public addresses. When
853 <literal>prefer-public
</literal>, enables the privacy extensions, but prefers public
854 addresses over temporary addresses. When false, the privacy extensions remain disabled. When
855 <literal>kernel
</literal>, the kernel's default setting will be left in place. When unspecified,
856 the value specified in the same setting in
857 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
858 which defaults to
<literal>no
</literal>, will be used.
</para>
860 <xi:include href=
"version-info.xml" xpointer=
"v222"/>
865 <term><varname>IPv6AcceptRA=
</varname></term>
867 <para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
868 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they
869 may trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or
870 if no routers are found on the link. The default is to disable RA reception for bridge
871 devices or when IP forwarding is enabled, and to enable it otherwise. Cannot be enabled on
872 devices aggregated in a bond device or when link-local addressing is disabled.
</para>
874 <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA]
875 section, see below.
</para>
878 <ulink url=
"https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl
</ulink>
879 in the kernel documentation regarding
<literal>accept_ra
</literal>, but note that systemd's
880 setting of
<constant>1</constant> (i.e. true) corresponds to kernel's setting of
881 <constant>2</constant>.
</para>
883 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
884 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
885 RA protocol is used, and the kernel's own implementation remains disabled, since
886 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
887 and these are not available from the kernel if the kernel's own implementation is used.
890 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
895 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
897 <para>Configures the amount of IPv6 Duplicate Address Detection (DAD) probes to send. When
898 unset, the kernel's default will be used.
</para>
900 <xi:include href=
"version-info.xml" xpointer=
"v228"/>
905 <term><varname>IPv6HopLimit=
</varname></term>
907 <para>Configures IPv6 Hop Limit. Takes an integer in the range
1…
255. For each router that
908 forwards the packet, the hop limit is decremented by
1. When the hop limit field reaches zero, the
909 packet is discarded. When unset, the kernel's default will be used.
</para>
911 <xi:include href=
"version-info.xml" xpointer=
"v228"/>
916 <term><varname>IPv6RetransmissionTimeSec=
</varname></term>
918 <para>Configures IPv6 Retransmission Time. The time between retransmitted Neighbor
919 Solicitation messages. Used by address resolution and the Neighbor Unreachability
920 Detection algorithm. A value of zero is ignored and the kernel's current value
921 will be used. Defaults to unset, and the kernel's current value will be used.
</para>
923 <xi:include href=
"version-info.xml" xpointer=
"v256"/>
928 <term><varname>IPv4ReversePathFilter=
</varname></term>
930 <para>Configure IPv4 Reverse Path Filtering. If enabled, when an IPv4 packet is received, the machine will first check
931 whether the
<emphasis>source
</emphasis> of the packet would be routed through the interface it came in. If there is no
932 route to the source on that interface, the machine will drop the packet. Takes one of
933 <literal>no
</literal>,
<literal>strict
</literal>, or
<literal>loose
</literal>. When
<literal>no
</literal>,
934 no source validation will be done. When
<literal>strict
</literal>, mode each incoming packet is tested against the FIB and
935 if the incoming interface is not the best reverse path, the packet check will fail. By default failed packets are discarded.
936 When
<literal>loose
</literal>, mode each incoming packet's source address is tested against the FIB. The packet is dropped
937 only if the source address is not reachable via any interface on that router.
938 See
<ulink url=
"https://tools.ietf.org/html/rfc1027">RFC
3704</ulink>.
939 When unset, the kernel's default will be used.
</para>
941 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
946 <term><varname>IPv4AcceptLocal=
</varname></term>
948 <para>Takes a boolean. Accept packets with local source addresses. In combination with
949 suitable routing, this can be used to direct packets between two local interfaces over the
950 wire and have them accepted properly. When unset, the kernel's default will be used.
</para>
952 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
957 <term><varname>IPv4RouteLocalnet=
</varname></term>
959 <para>Takes a boolean. When true, the kernel does not consider loopback addresses as martian
960 source or destination while routing. This enables the use of
127.0.0.0/
8 for local routing
961 purposes. When unset, the kernel's default will be used.
</para>
963 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
968 <term><varname>IPv4ProxyARP=
</varname></term>
970 <para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one
971 host, usually a router, answers ARP requests intended for another machine. By
"faking" its
972 identity, the router accepts responsibility for routing packets to the
"real" destination.
973 See
<ulink url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>. When unset, the
974 kernel's default will be used.
</para>
976 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
981 <term><varname>IPv4ProxyARPPrivateVLAN=
</varname></term>
983 <para>Takes a boolean. Configures proxy ARP private VLAN for IPv4, also known as VLAN aggregation,
984 private VLAN, source-port filtering, port-isolation, or MAC-forced forwarding.
</para>
986 <para>This variant of the ARP proxy technique will allow the ARP proxy to reply back to the same
989 <para>See
<ulink url=
"https://tools.ietf.org/html/rfc3069">RFC
3069</ulink>. When unset,
990 the kernel's default will be used.
</para>
991 <xi:include href=
"version-info.xml" xpointer=
"v256"/>
996 <term><varname>IPv6ProxyNDP=
</varname></term>
998 <para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery Protocol)
999 is a technique for IPv6 to allow routing of addresses to a different destination when peers
1000 expect them to be present on a certain physical link. In this case a router answers Neighbour
1001 Advertisement messages intended for another machine by offering its own MAC address as
1002 destination. Unlike proxy ARP for IPv4, it is not enabled globally, but will only send
1003 Neighbour Advertisement messages for addresses in the IPv6 neighbor proxy table, which can
1004 also be shown by
<command>ip -
6 neighbour show proxy
</command>. systemd-networkd will control
1005 the per-interface `proxy_ndp` switch for each configured interface depending on this option.
1006 When unset, the kernel's default will be used.
</para>
1008 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1013 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
1015 <para>An IPv6 address, for which Neighbour Advertisement messages will be proxied. This
1016 option may be specified more than once. systemd-networkd will add the
1017 <varname>IPv6ProxyNDPAddress=
</varname> entries to the kernel's IPv6 neighbor proxy table.
1018 This setting implies
<varname>IPv6ProxyNDP=yes
</varname> but has no effect if
1019 <varname>IPv6ProxyNDP=
</varname> has been set to false. When unset, the kernel's default will
1022 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
1027 <term><varname>IPv6SendRA=
</varname></term>
1029 <para>Whether to enable or disable Router Advertisement sending on a link. Takes a boolean
1030 value. When enabled, prefixes configured in [IPv6Prefix] sections and routes configured in
1031 the [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA] section. If
1032 <varname>DHCPPrefixDelegation=
</varname> is enabled, then the delegated prefixes are also
1033 distributed. See
<varname>DHCPPrefixDelegation=
</varname> setting and the [IPv6SendRA],
1034 [IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation] sections for more configuration
1037 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
1042 <term><varname>DHCPPrefixDelegation=
</varname></term>
1044 <para>Takes a boolean value. When enabled, requests subnet prefixes on another link via the DHCPv6
1045 protocol or via the
6RD option in the DHCPv4 protocol. An address within each delegated prefix will
1046 be assigned, and the prefixes will be announced through IPv6 Router Advertisement if
1047 <varname>IPv6SendRA=
</varname> is enabled. This behaviour can be configured in the
1048 [DHCPPrefixDelegation] section. Defaults to disabled.
</para>
1050 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
1055 <term><varname>IPv6MTUBytes=
</varname></term>
1057 <para>Configures IPv6 maximum transmission unit (MTU). An integer greater than or equal to
1058 1280 bytes. When unset, the kernel's default will be used.
</para>
1060 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
1065 <term><varname>KeepMaster=
</varname></term>
1067 <para>Takes a boolean value. When enabled, the current master interface index will not be
1068 changed, and
<varname>BatmanAdvanced=
</varname>,
<varname>Bond=
</varname>,
1069 <varname>Bridge=
</varname>, and
<varname>VRF=
</varname> settings are ignored. This may be
1070 useful when a netdev with a master interface is created by another program, e.g.
1071 <citerefentry><refentrytitle>systemd-nspawn
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
1072 Defaults to false.
</para>
1074 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
1079 <term><varname>BatmanAdvanced=
</varname></term>
1080 <term><varname>Bond=
</varname></term>
1081 <term><varname>Bridge=
</varname></term>
1082 <term><varname>VRF=
</varname></term>
1084 <para>The name of the B.A.T.M.A.N. Advanced, bond, bridge, or VRF interface to add the link
1086 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1089 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1094 <term><varname>IPoIB=
</varname></term>
1095 <term><varname>IPVLAN=
</varname></term>
1096 <term><varname>IPVTAP=
</varname></term>
1097 <term><varname>MACsec=
</varname></term>
1098 <term><varname>MACVLAN=
</varname></term>
1099 <term><varname>MACVTAP=
</varname></term>
1100 <term><varname>Tunnel=
</varname></term>
1101 <term><varname>VLAN=
</varname></term>
1102 <term><varname>VXLAN=
</varname></term>
1103 <term><varname>Xfrm=
</varname></term>
1105 <para>The name of an IPoIB, IPVLAN, IPVTAP, MACsec, MACVLAN, MACVTAP, tunnel, VLAN,
1106 VXLAN, or Xfrm to be created on the link. See
1107 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1108 This option may be specified more than once.
</para>
1110 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1115 <term><varname>ActiveSlave=
</varname></term>
1117 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
1118 option is only valid for following modes:
<literal>active-backup
</literal>,
1119 <literal>balance-alb
</literal>, and
<literal>balance-tlb
</literal>. Defaults to false.
</para>
1121 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1126 <term><varname>PrimarySlave=
</varname></term>
1128 <para>Takes a boolean. Specifies which slave is the primary device. The specified device will
1129 always be the active slave while it is available. Only when the primary is off-line will
1130 alternate devices be used. This is useful when one slave is preferred over another, e.g.
1131 when one slave has higher throughput than another. The
<literal>PrimarySlave=
</literal>
1132 option is only valid for following modes:
<literal>active-backup
</literal>,
1133 <literal>balance-alb
</literal>, and
<literal>balance-tlb
</literal>. Defaults to false.
</para>
1135 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1140 <term><varname>ConfigureWithoutCarrier=
</varname></term>
1142 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no
1143 carrier. Defaults to false. If enabled, and the
<varname>IgnoreCarrierLoss=
</varname> setting
1144 is not explicitly set, then it is enabled as well.
</para>
1146 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1151 <term><varname>IgnoreCarrierLoss=
</varname></term>
1153 <para>Takes a boolean or a timespan. When true,
<command>systemd-networkd
</command> retains
1154 both the static and dynamic configuration of the interface even if its carrier is lost. When
1155 false,
<command>systemd-networkd
</command> drops both the static and dynamic configuration of
1156 the interface. When a timespan is specified,
<command>systemd-networkd
</command> waits for
1157 the specified timespan, and ignores the carrier loss if the link regain its carrier within
1158 the timespan. Setting
0 seconds is equivalent to
<literal>no
</literal>, and
1159 <literal>infinite
</literal> is equivalent to
<literal>yes
</literal>.
</para>
1161 <para>Setting a finite timespan may be useful when e.g. in the following cases:
1164 <para>A wireless interface connecting to a network which has multiple access points with
1165 the same SSID.
</para>
1168 <para>Enslaving a wireless interface to a bond interface, which may disconnect from the
1169 connected access point and causes its carrier to be lost.
</para>
1172 <para>The driver of the interface resets when the MTU is changed.
</para>
1177 <para>When
<varname>Bond=
</varname> is specified to a wireless interface, defaults to
3
1178 seconds. When the DHCPv4 client is enabled and
<varname>UseMTU=
</varname> in the [DHCPv4]
1179 section enabled, defaults to
5 seconds. Otherwise, defaults to the value specified with
1180 <varname>ConfigureWithoutCarrier=
</varname>. When
<varname>ActivationPolicy=
</varname> is set
1181 to
<literal>always-up
</literal>, this is forced to
<literal>yes
</literal>, and ignored any
1182 user specified values.
</para>
1184 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
1189 <term><varname>KeepConfiguration=
</varname></term>
1191 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
1192 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
1193 will not drop static addresses and routes on starting up process. When set to
1194 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
1195 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
1196 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
1197 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
1198 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
1199 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
1200 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
1201 <literal>dhcp-on-stop
</literal> when
<command>systemd-networkd
</command> is running in
1202 initrd,
<literal>yes
</literal> when the root filesystem is a network filesystem, and
1203 <literal>no
</literal> otherwise.
</para>
1205 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
1212 <title>[Address] Section Options
</title>
1214 <para>An [Address] section accepts the following keys. Specify several [Address] sections to
1215 configure several addresses.
</para>
1217 <variablelist class='network-directives'
>
1219 <term><varname>Address=
</varname></term>
1221 <para>As in the [Network] section. This setting is mandatory. Each [Address] section can
1222 contain one
<varname>Address=
</varname> setting.
</para>
1224 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1229 <term><varname>Peer=
</varname></term>
1231 <para>The peer address in a point-to-point connection. Accepts the same format as the
1232 <varname>Address=
</varname> setting.
</para>
1234 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
1239 <term><varname>Broadcast=
</varname></term>
1241 <para>Takes an IPv4 address or boolean value. The address must be in the format described in
1242 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1243 If set to true, then the IPv4 broadcast address will be derived from the
1244 <varname>Address=
</varname> setting. If set to false, then the broadcast address will not be
1245 set. Defaults to true, except for wireguard interfaces, where it default to false.
</para>
1247 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1252 <term><varname>Label=
</varname></term>
1254 <para>Specifies the label for the IPv4 address. The label must be a
7-bit ASCII string with
1255 a length of
1…
15 characters. Defaults to unset.
</para>
1257 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1262 <term><varname>PreferredLifetime=
</varname></term>
1264 <para>Allows the default
"preferred lifetime" of the address to be overridden. Only three
1265 settings are accepted:
<literal>forever
</literal>,
<literal>infinity
</literal>, which is the
1266 default and means that the address never expires, and
<literal>0</literal>, which means that
1267 the address is considered immediately
"expired" and will not be used, unless explicitly
1268 requested. A setting of
<option>PreferredLifetime=
0</option> is useful for addresses which
1269 are added to be used only by a specific application, which is then configured to use them
1272 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
1277 <term><varname>Scope=
</varname></term>
1279 <para>The scope of the address, which can be
<literal>global
</literal> (valid everywhere on
1280 the network, even through a gateway),
<literal>link
</literal> (only valid on this device,
1281 will not traverse a gateway) or
<literal>host
</literal> (only valid within the device itself,
1282 e.g.
127.0.0.1) or an integer in the range
0…
255. Defaults to
<literal>global
</literal>.
1283 IPv4 only - IPv6 scope is automatically assigned by the kernel and cannot be set manually.
1286 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1291 <term><varname>RouteMetric=
</varname></term>
1293 <para>The metric of the prefix route, which is pointing to the subnet of the configured IP
1294 address, taking the configured prefix length into account. Takes an unsigned integer in the
1295 range
0…
4294967295. When unset or set to
0, the kernel's default value is used. This
1296 setting will be ignored when
<varname>AddPrefixRoute=
</varname> is false.
</para>
1298 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
1303 <term><varname>HomeAddress=
</varname></term>
1305 <para>Takes a boolean. Designates this address the
"home address" as defined in
1306 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>. Supported only on IPv6.
1307 Defaults to false.
</para>
1309 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1314 <term><varname>DuplicateAddressDetection=
</varname></term>
1316 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
<literal>both
</literal>,
1317 or
<literal>none
</literal>. When
<literal>ipv4
</literal>, performs IPv4 Address Conflict
1318 Detection. See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>.
1319 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
1320 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>. Defaults to
1321 <literal>ipv4
</literal> for IPv4 link-local addresses,
<literal>ipv6
</literal> for IPv6
1322 addresses, and
<literal>none
</literal> otherwise.
</para>
1324 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1329 <term><varname>ManageTemporaryAddress=
</varname></term>
1331 <para>Takes a boolean. If true the kernel manage temporary addresses created from this one as
1332 template on behalf of Privacy Extensions
1333 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become active,
1334 the use_tempaddr sysctl setting has to be set to a value greater than zero. The given address
1335 needs to have a prefix length of
64. This flag allows using privacy extensions in a manually
1336 configured network, just like if stateless auto-configuration was active. Defaults to false.
1339 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1344 <term><varname>AddPrefixRoute=
</varname></term>
1346 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
1347 Defaults to true.
</para>
1349 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
1354 <term><varname>AutoJoin=
</varname></term>
1356 <para>Takes a boolean. Joining multicast group on ethernet level via
1357 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
1358 IGMP snooping since the switch would not replicate multicast packets on ports that did not
1359 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
1360 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
1361 that enables them to do the required join. By extending
<command>ip address
</command> command
1362 with option
<literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS)
1363 vxlan interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
1364 Defaults to
<literal>no
</literal>.
</para>
1366 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
1371 <term><varname>NetLabel=
</varname><replaceable>label
</replaceable></term>
1374 <para>This setting provides a method for integrating static and dynamic network configuration into
1375 Linux
<ulink url=
"https://docs.kernel.org/netlabel/index.html">NetLabel
</ulink> subsystem rules,
1376 used by
<ulink url=
"https://en.wikipedia.org/wiki/Linux_Security_Modules">Linux Security Modules
1377 (LSMs)
</ulink> for network access control. The label, with suitable LSM rules, can be used to
1378 control connectivity of (for example) a service with peers in the local network. At least with
1379 SELinux, only the ingress can be controlled but not egress. The benefit of using this setting is
1380 that it may be possible to apply interface independent part of NetLabel configuration at very early
1381 stage of system boot sequence, at the time when the network interfaces are not available yet, with
1383 project='man-pages'
><refentrytitle>netlabelctl
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1384 and the per-interface configuration with
<command>systemd-networkd
</command> once the interfaces
1385 appear later. Currently this feature is only implemented for SELinux.
</para>
1387 <para>The option expects a single NetLabel label. The label must conform to lexical restrictions of
1388 LSM labels. When an interface is configured with IP addresses, the addresses and subnetwork masks
1389 will be appended to the
<ulink
1390 url=
"https://github.com/SELinuxProject/selinux-notebook/blob/main/src/network_support.md">NetLabel
1391 Fallback Peer Labeling
</ulink> rules. They will be removed when the interface is
1392 deconfigured. Failures to manage the labels will be ignored.
</para>
1395 <para>Once labeling is enabled for network traffic, a lot of LSM access control points in
1396 Linux networking stack go from dormant to active. Care should be taken to avoid getting into a
1397 situation where for example remote connectivity is broken, when the security policy hasn't been
1398 updated to consider LSM per-packet access controls and no rules would allow any network
1399 traffic. Also note that additional configuration with
<citerefentry
1400 project='man-pages'
><refentrytitle>netlabelctl
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1405 <programlisting>[Address]
1406 NetLabel=system_u:object_r:localnet_peer_t:s0
</programlisting>
1408 With the example rules applying for interface
<literal>eth0
</literal>, when the interface is
1409 configured with an IPv4 address of
10.0.0.123/
8,
<command>systemd-networkd
</command> performs the
1410 equivalent of
<command>netlabelctl
</command> operation
1412 <programlisting>netlabelctl unlbl add interface eth0 address:
10.0.0.0/
8 label:system_u:object_r:localnet_peer_t:s0
</programlisting>
1414 and the reverse operation when the IPv4 address is deconfigured. The configuration can be used with
1415 LSM rules; in case of SELinux to allow a SELinux domain to receive data from objects of SELinux
1416 <literal>peer
</literal> class. For example:
1418 <programlisting>type localnet_peer_t;
1419 allow my_server_t localnet_peer_t:peer recv;
</programlisting>
1421 The effect of the above configuration and rules (in absence of other rules as may be the case) is
1422 to only allow
<literal>my_server_t
</literal> (and nothing else) to receive data from local subnet
1423 10.0.0.0/
8 of interface
<literal>eth0
</literal>.
1426 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
1431 <term><varname>NFTSet=
</varname><replaceable>source
</replaceable>:
<replaceable>family
</replaceable>:
<replaceable>table
</replaceable>:
<replaceable>set
</replaceable></term>
1433 <para>This setting provides a method for integrating network configuration into firewall rules with
1434 <ulink url=
"https://netfilter.org/projects/nftables/index.html">NFT
</ulink> sets. The benefit of
1435 using the setting is that static network configuration (or dynamically obtained network addresses,
1436 see similar directives in other sections) can be used in firewall rules with the indirection of NFT
1437 set types. For example, access could be granted for hosts in the local subnetwork only. Firewall
1438 rules using IP address of an interface are also instantly updated when the network configuration
1439 changes, for example via DHCP.
</para>
1441 <para>This option expects a whitespace separated list of NFT set definitions. Each definition
1442 consists of a colon-separated tuple of source type (one of
<literal>address
</literal>,
1443 <literal>prefix
</literal> or
<literal>ifindex
</literal>), NFT address family (one of
1444 <literal>arp
</literal>,
<literal>bridge
</literal>,
<literal>inet
</literal>,
<literal>ip
</literal>,
1445 <literal>ip6
</literal>, or
<literal>netdev
</literal>), table name and set name. The names of tables
1446 and sets must conform to lexical restrictions of NFT table names. The type of the element used in
1447 the NFT filter must match the type implied by the directive (
<literal>address
</literal>,
1448 <literal>prefix
</literal> or
<literal>ifindex
</literal>) and address type (IPv4 or IPv6) as shown
1449 in the table below.
</para>
1452 <title>Defined
<varname>source type
</varname> values
</title>
1454 <colspec colname='source type'
/>
1455 <colspec colname='description'
/>
1456 <colspec colname='NFT type name'
/>
1459 <entry>Source type
</entry>
1460 <entry>Description
</entry>
1461 <entry>Corresponding NFT type name
</entry>
1467 <entry><literal>address
</literal></entry>
1468 <entry>host IP address
</entry>
1469 <entry><literal>ipv4_addr
</literal> or
<literal>ipv6_addr
</literal></entry>
1472 <entry><literal>prefix
</literal></entry>
1473 <entry>network prefix
</entry>
1474 <entry><literal>ipv4_addr
</literal> or
<literal>ipv6_addr
</literal>, with
<literal>flags interval
</literal></entry>
1477 <entry><literal>ifindex
</literal></entry>
1478 <entry>interface index
</entry>
1479 <entry><literal>iface_index
</literal></entry>
1485 <para>When an interface is configured with IP addresses, the addresses, subnetwork masks or
1486 interface index will be appended to the NFT sets. The information will be removed when the
1487 interface is deconfigured.
<command>systemd-networkd
</command> only inserts elements to (or removes
1488 from) the sets, so the related NFT rules, tables and sets must be prepared elsewhere in
1489 advance. Failures to manage the sets will be ignored.
</para>
1492 <programlisting>[Address]
1493 NFTSet=prefix:netdev:filter:eth_ipv4_prefix
</programlisting>
1494 Corresponding NFT rules:
1495 <programlisting>table netdev filter {
1496 set eth_ipv4_prefix {
1501 type filter hook ingress device
"eth0" priority filter; policy drop;
1502 ip daddr != @eth_ipv4_prefix drop
1508 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
1515 <title>[Neighbor] Section Options
</title>
1517 <para>A [Neighbor] section accepts the following keys. The neighbor section adds a permanent,
1518 static entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the
1519 links matched for the network. Specify several [Neighbor] sections to configure several static
1522 <variablelist class='network-directives'
>
1524 <term><varname>Address=
</varname></term>
1526 <para>The IP address of the neighbor.
</para>
1528 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1533 <term><varname>LinkLayerAddress=
</varname></term>
1535 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
1537 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
1544 <title>[IPv6AddressLabel] Section Options
</title>
1546 <para>An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel]
1547 sections to configure several address labels. IPv6 address labels are used for address selection.
1548 See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>. Precedence is managed by
1549 userspace, and only the label itself is stored in the kernel.
</para>
1551 <variablelist class='network-directives'
>
1553 <term><varname>Label=
</varname></term>
1555 <para>The label for the prefix, an unsigned integer in the range
0…
4294967294.
0xffffffff is
1556 reserved. This setting is mandatory.
</para>
1558 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1563 <term><varname>Prefix=
</varname></term>
1565 <para>IPv6 prefix is an address with a prefix length, separated by a slash
1566 <literal>/
</literal> character. This setting is mandatory.
</para>
1568 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1575 <title>[RoutingPolicyRule] Section Options
</title>
1577 <para>An [RoutingPolicyRule] section accepts the following settings. Specify several
1578 [RoutingPolicyRule] sections to configure several rules.
</para>
1580 <variablelist class='network-directives'
>
1582 <term><varname>TypeOfService=
</varname></term>
1585 This specifies the Type of Service (ToS) field of packets to match;
1586 it takes an unsigned integer in the range
0…
255.
1587 The field can be used to specify precedence (the first
3 bits) and ToS (the next
3 bits).
1588 The field can be also used to specify Differentiated Services Code Point (DSCP) (the first
6 bits) and
1589 Explicit Congestion Notification (ECN) (the last
2 bits).
1590 See
<ulink url=
"https://en.wikipedia.org/wiki/Type_of_service">Type of Service
</ulink>
1591 and
<ulink url=
"https://en.wikipedia.org/wiki/Differentiated_services">Differentiated services
</ulink>
1595 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1600 <term><varname>From=
</varname></term>
1602 <para>Specifies the source address prefix to match. Possibly followed by a slash and the
1603 prefix length.
</para>
1605 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1610 <term><varname>To=
</varname></term>
1612 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the
1613 prefix length.
</para>
1615 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1620 <term><varname>FirewallMark=
</varname></term>
1622 <para>Specifies the iptables firewall mark value to match (a number in the range
1623 1…
4294967295). Optionally, the firewall mask (also a number between
1…
4294967295) can be
1624 suffixed with a slash (
<literal>/
</literal>), e.g.,
<literal>7/
255</literal>.
</para>
1626 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1631 <term><varname>Table=
</varname></term>
1633 <para>Specifies the routing table identifier to look up if the rule selector matches. Takes
1634 one of predefined names
<literal>default
</literal>,
<literal>main
</literal>, and
1635 <literal>local
</literal>, and names defined in
<varname>RouteTable=
</varname> in
1636 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1637 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1639 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1644 <term><varname>Priority=
</varname></term>
1646 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an integer in the
1647 range
0…
4294967295. Higher number means lower priority, and rules get processed in order of
1648 increasing number. Defaults to unset, and the kernel will pick a value dynamically.
</para>
1650 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
1655 <term><varname>IncomingInterface=
</varname></term>
1657 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches
1658 packets originating from this host.
</para>
1660 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
1665 <term><varname>OutgoingInterface=
</varname></term>
1667 <para>Specifies the outgoing device to match. The outgoing interface is only available for
1668 packets originating from local sockets that are bound to a device.
</para>
1670 <xi:include href=
"version-info.xml" xpointer=
"v236"/>
1675 <term><varname>L3MasterDevice=
</varname></term>
1677 <para>A boolean. Specifies whether the rule is to direct lookups to the tables associated with
1678 level
3 master devices (also known as Virtual Routing and Forwarding or VRF devices).
1679 For further details see
<ulink url=
"https://docs.kernel.org/networking/vrf.html">
1680 Virtual Routing and Forwarding (VRF)
</ulink>. Defaults to false.
</para>
1682 <xi:include href=
"version-info.xml" xpointer=
"v256"/>
1687 <term><varname>SourcePort=
</varname></term>
1689 <para>Specifies the source IP port or IP port range match in forwarding information base
1690 (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
1691 Defaults to unset.
</para>
1693 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1698 <term><varname>DestinationPort=
</varname></term>
1700 <para>Specifies the destination IP port or IP port range match in forwarding information base
1701 (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
1702 Defaults to unset.
</para>
1704 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1709 <term><varname>IPProtocol=
</varname></term>
1711 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP
1712 protocol name such as
<literal>tcp
</literal>,
<literal>udp
</literal> or
1713 <literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
1714 <literal>tcp
</literal> or
<literal>17</literal> for
<literal>udp
</literal>. Defaults to unset.
1717 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1722 <term><varname>InvertRule=
</varname></term>
1724 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1726 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
1731 <term><varname>Family=
</varname></term>
1733 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1734 <literal>both
</literal>. By default, the address family is determined by the address
1735 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1736 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1737 <literal>ipv4
</literal>.
</para>
1739 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
1744 <term><varname>User=
</varname></term>
1746 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1749 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
1754 <term><varname>SuppressPrefixLength=
</varname></term>
1756 <para>Takes a number
<replaceable>N
</replaceable> in the range
0…
128 and rejects routing
1757 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1760 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
1765 <term><varname>SuppressInterfaceGroup=
</varname></term>
1767 <para>Takes an integer in the range
0…
2147483647 and rejects routing decisions that have
1768 an interface with the same group id. It has the same meaning as
1769 <option>suppress_ifgroup
</option> in
<command>ip rule
</command>. Defaults to unset.
</para>
1771 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
1776 <term><varname>Type=
</varname></term>
1778 <para>Specifies Routing Policy Database (RPDB) rule type. Takes one of
1779 <literal>blackhole
</literal>,
<literal>unreachable
</literal> or
<literal>prohibit
</literal>.
1782 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1789 <title>[NextHop] Section Options
</title>
1791 <para>The [NextHop] section is used to manipulate entries in the kernel's
"nexthop" tables. The
1792 [NextHop] section accepts the following settings. Specify several [NextHop] sections to configure
1793 several hops.
</para>
1795 <variablelist class='network-directives'
>
1797 <term><varname>Id=
</varname></term>
1799 <para>The id of the next hop. Takes an integer in the range
1…
4294967295.
1800 This is mandatory if
<varname>ManageForeignNextHops=no
</varname> is specified in
1801 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1802 Otherwise, if unspecified, an unused ID will be automatically picked.
</para>
1804 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
1809 <term><varname>Gateway=
</varname></term>
1811 <para>As in the [Network] section.
</para>
1813 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
1818 <term><varname>Family=
</varname></term>
1820 <para>Takes one of the special values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>.
1821 By default, the family is determined by the address specified in
1822 <varname>Gateway=
</varname>. If
<varname>Gateway=
</varname> is not specified, then defaults
1823 to
<literal>ipv4
</literal>.
</para>
1825 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1830 <term><varname>OnLink=
</varname></term>
1832 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1833 reachable directly by the current machine (i.e., attached to the local network), so that we
1834 can insert the nexthop in the kernel table without it being complained about. Defaults to
1835 <literal>no
</literal>.
</para>
1837 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1842 <term><varname>Blackhole=
</varname></term>
1844 <para>Takes a boolean. If enabled, packets to the corresponding routes are discarded
1845 silently, and
<varname>Gateway=
</varname> cannot be specified. Defaults to
1846 <literal>no
</literal>.
</para>
1848 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
1853 <term><varname>Group=
</varname></term>
1855 <para>Takes a whitespace separated list of nexthop IDs. Each ID must be in the range
1856 1…
4294967295. Optionally, each nexthop ID can take a weight after a colon
1857 (
<literal><replaceable>id
</replaceable><optional>:
<replaceable>weight
</replaceable></optional></literal>).
1858 The weight must be in the range
1…
255. If the weight is not specified, then it is assumed
1859 that the weight is
1. This setting cannot be specified with
<varname>Gateway=
</varname>,
1860 <varname>Family=
</varname>,
<varname>Blackhole=
</varname>. This setting can be specified
1861 multiple times. If an empty string is assigned, then the all previous assignments are
1862 cleared. Defaults to unset.
</para>
1864 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
1871 <title>[Route] Section Options
</title>
1873 <para>The [Route] section accepts the following settings. Specify several [Route] sections to
1874 configure several routes.
</para>
1876 <variablelist class='network-directives'
>
1878 <term><varname>Gateway=
</varname></term>
1880 <para>Takes the gateway address or the special values
<literal>_dhcp4
</literal> and
1881 <literal>_ipv6ra
</literal>. If
<literal>_dhcp4
</literal> or
<literal>_ipv6ra
</literal> is
1882 set, then the gateway address provided by DHCPv4 or IPv6 RA is used.
</para>
1884 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1889 <term><varname>GatewayOnLink=
</varname></term>
1891 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1892 reachable directly by the current machine (i.e., attached to the local network), so that we
1893 can insert the route in the kernel table without it being complained about. Defaults to
1894 <literal>no
</literal>.
</para>
1896 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1901 <term><varname>Destination=
</varname></term>
1903 <para>The destination prefix of the route. Possibly followed by a slash and the prefix
1904 length. If omitted, a full-length host route is assumed.
</para>
1906 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
1911 <term><varname>Source=
</varname></term>
1913 <para>The source prefix of the route. Possibly followed by a slash and the prefix length. If
1914 omitted, a full-length host route is assumed.
</para>
1916 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
1921 <term><varname>Metric=
</varname></term>
1923 <para>The metric of the route. Takes an unsigned integer in the range
0…
4294967295. Defaults
1924 to unset, and the kernel's default will be used.
</para>
1926 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
1931 <term><varname>IPv6Preference=
</varname></term>
1933 <para>Specifies the route preference as defined in
1934 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink> for Router Discovery
1935 messages. Which can be one of
<literal>low
</literal> the route has a lowest priority,
1936 <literal>medium
</literal> the route has a default priority or
<literal>high
</literal> the
1937 route has a highest priority.
</para>
1939 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
1944 <term><varname>Scope=
</varname></term>
1946 <para>The scope of the IPv4 route, which can be
<literal>global
</literal>,
1947 <literal>site
</literal>,
<literal>link
</literal>,
<literal>host
</literal>, or
1948 <literal>nowhere
</literal>:
</para>
1951 <para><literal>global
</literal> means the route can reach hosts more than one hop away.
1956 <para><literal>site
</literal> means an interior route in the local autonomous system.
1961 <para><literal>link
</literal> means the route can only reach hosts on the local network
1962 (one hop away).
</para>
1966 <para><literal>host
</literal> means the route will not leave the local machine (used for
1967 internal addresses like
127.0.0.1).
</para>
1971 <para><literal>nowhere
</literal> means the destination doesn't exist.
</para>
1975 <para>For IPv4 route, defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
1976 <literal>local
</literal> or
<literal>nat
</literal>, and
<literal>link
</literal> if
1977 <varname>Type=
</varname> is
<literal>broadcast
</literal>,
<literal>multicast
</literal>,
1978 <literal>anycast
</literal>, or
<literal>unicast
</literal>. In other cases,
1979 defaults to
<literal>global
</literal>. The value is not used for IPv6.
</para>
1981 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
1986 <term><varname>PreferredSource=
</varname></term>
1988 <para>The preferred source address of the route. The address must be in the format described
1990 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1993 <xi:include href=
"version-info.xml" xpointer=
"v227"/>
1998 <term><varname>Table=
</varname></term>
2000 <para>The table identifier for the route. Takes one of predefined names
2001 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
2002 defined in
<varname>RouteTable=
</varname> in
2003 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2004 or a number between
1 and
4294967295. The table can be retrieved using
2005 <command>ip route show table
<replaceable>num
</replaceable></command>. If unset and
2006 <varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
2007 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
2008 In other cases, defaults to
<literal>main
</literal>. Ignored if
<varname>L3MasterDevice=
</varname> is true.
</para>
2010 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2015 <term><varname>HopLimit=
</varname></term>
2017 <para>Configures per route hop limit. Takes an integer in the range
1…
255. See also
2018 <varname>IPv6HopLimit=
</varname>.
</para>
2020 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2025 <term><varname>Protocol=
</varname></term>
2027 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special
2028 values
<literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
2029 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
2032 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
2037 <term><varname>Type=
</varname></term>
2039 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
2040 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
2041 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
2042 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
2043 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e.
2044 a route indicating the path to take to a destination network address. If
2045 <literal>blackhole
</literal>, packets to the defined route are discarded silently. If
2046 <literal>unreachable
</literal>, packets to the defined route are discarded and the ICMP
2047 message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets to the
2048 defined route are discarded and the ICMP message
"Communication Administratively Prohibited"
2049 is generated. If
<literal>throw
</literal>, route lookup in the current routing table will
2050 fail and the route selection process will return to Routing Policy Database (RPDB). Defaults
2051 to
<literal>unicast
</literal>.
</para>
2053 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
2058 <term><varname>InitialCongestionWindow=
</varname></term>
2060 <para>The TCP initial congestion window is used during the start of a TCP connection.
2061 During the start of a TCP session, when a client requests a resource, the server's initial
2062 congestion window determines how many packets will be sent during the initial burst of data
2063 without waiting for acknowledgement. Takes a number between
1 and
1023. Note that
100 is
2064 considered an extremely large value for this option. When unset, the kernel's default
2065 (typically
10) will be used.
</para>
2067 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
2072 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
2074 <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
2075 that can initially be buffered at one time on a connection. The sending host can send only
2076 that amount of data before waiting for an acknowledgment and window update from the
2077 receiving host. Takes a number between
1 and
1023. Note that
100 is considered an extremely
2078 large value for this option. When unset, the kernel's default will be used.
</para>
2080 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
2085 <term><varname>QuickAck=
</varname></term>
2087 <para>Takes a boolean. When true, the TCP quick ACK mode for the route is enabled. When unset,
2088 the kernel's default will be used.
</para>
2090 <xi:include href=
"version-info.xml" xpointer=
"v237"/>
2095 <term><varname>FastOpenNoCookie=
</varname></term>
2097 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
2098 When unset, the kernel's default will be used.
</para>
2100 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2105 <term><varname>MTUBytes=
</varname></term>
2107 <para>The maximum transmission unit in bytes to set for the route. The usual suffixes K, M,
2108 G, are supported and are understood to the base of
1024.
</para>
2110 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
2115 <term><varname>TCPAdvertisedMaximumSegmentSize=
</varname></term>
2117 <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G,
2118 are supported and are understood to the base of
1024. An unsigned integer in the range
2119 1…
4294967294. When unset, the kernel's default will be used.
</para>
2121 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2126 <term><varname>TCPCongestionControlAlgorithm=
</varname></term>
2128 <para>Specifies the TCP congestion control algorithm for the route. Takes a name of the algorithm,
2129 e.g.
<literal>bbr
</literal>,
<literal>dctcp
</literal>, or
<literal>vegas
</literal>. When unset,
2130 the kernel's default will be used.
</para>
2132 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2137 <term><varname>TCPRetransmissionTimeoutSec=
</varname></term>
2139 <para>Specifies the TCP Retransmission Timeout (RTO) for the route. Takes time values in seconds.
2140 This value specifies the timeout of an alive TCP connection, when retransmissions remain
2141 unacknowledged. When unset, the kernel's default will be used.
</para>
2143 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2148 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
2150 <para>Configures multipath route. Multipath routing is the technique of using multiple
2151 alternative paths through a network. Takes gateway address. Optionally, takes a network
2152 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for this
2153 multipath route separated with whitespace. This setting can be specified multiple times. If
2154 an empty string is assigned, then the all previous assignments are cleared.
</para>
2156 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2161 <term><varname>NextHop=
</varname></term>
2163 <para>Specifies the nexthop id. Takes an unsigned integer in the range
1…
4294967295. If set,
2164 the corresponding [NextHop] section must be configured. Defaults to unset.
</para>
2166 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2173 <title>[DHCPv4] Section Options
</title>
2175 <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
2176 <varname>DHCP=
</varname> setting described above:
</para>
2178 <variablelist class='network-directives'
>
2180 <!-- DHCP packet contents -->
2183 <term><varname>RequestAddress=
</varname></term>
2185 <para>Takes an IPv4 address. When specified, the Requested IP Address option (option code
50) is
2186 added with it to the initial DHCPDISCOVER message sent by the DHCP client. Defaults to unset, and
2187 an already assigned dynamic address to the interface is automatically picked.
</para>
2189 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2194 <term><varname>SendHostname=
</varname></term>
2196 <para>When true (the default), the machine's hostname (or the value specified with
2197 <varname>Hostname=
</varname>, described below) will be sent to the DHCP server. Note that the
2198 hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and be
2199 formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option
2202 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
2207 <term><varname>Hostname=
</varname></term>
2209 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's
2210 hostname. Note that the specified hostname must consist only of
7-bit ASCII lower-case
2211 characters and no spaces or dots, and be formatted as a valid DNS domain name.
</para>
2213 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
2218 <term><varname>MUDURL=
</varname></term>
2220 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent
2221 to the DHCPv4 server. Takes a URL of length up to
255 characters. A superficial verification
2222 that the string is a valid URL will be performed. DHCPv4 clients are intended to have at most
2223 one MUD URL associated with them. See
2224 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
2226 <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers
2227 to advertise device specifications, including the intended communication patterns for their
2228 device when it connects to the network. The network can then use this to author a
2229 context-specific access policy, so the device functions only within those parameters.
</para>
2231 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2236 <term><varname>ClientIdentifier=
</varname></term>
2238 <para>The DHCPv4 client identifier to use. Takes one of
<option>mac
</option> or
2239 <option>duid
</option>. If set to
<option>mac
</option>, the MAC address of the link is used. If set
2240 to
<option>duid
</option>, an RFC4361-compliant Client ID, which is the combination of IAID and
2241 DUID, is used. IAID can be configured by
<varname>IAID=
</varname>. DUID can be configured by
2242 <varname>DUIDType=
</varname> and
<varname>DUIDRawData=
</varname>. Defaults to
2243 <option>duid
</option>.
</para>
2245 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
2250 <term><varname>VendorClassIdentifier=
</varname></term>
2252 <para>The vendor class identifier used to identify vendor type and configuration.
</para>
2254 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2259 <term><varname>UserClass=
</varname></term>
2261 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or
2262 applications it represents. The information contained in this option is a string that
2263 represents the user class of which the client is a member. Each class sets an identifying
2264 string of information to be used by the DHCP service to classify clients. Takes a
2265 whitespace-separated list of strings.
</para>
2267 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
2272 <term><varname>DUIDType=
</varname></term>
2274 <para>Override the global
<varname>DUIDType=
</varname> setting for this network. See
2275 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2276 for a description of possible values.
</para>
2278 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2283 <term><varname>DUIDRawData=
</varname></term>
2285 <para>Override the global
<varname>DUIDRawData=
</varname> setting for this network. See
2286 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
2287 for a description of possible values.
</para>
2289 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2294 <term><varname>IAID=
</varname></term>
2296 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned
2299 <xi:include href=
"version-info.xml" xpointer=
"v230"/>
2304 <term><varname>RapidCommit=
</varname></term>
2306 <para>Takes a boolean. The DHCPv4 client can obtain configuration parameters from a DHCPv4 server
2307 through a rapid two-message exchange (discover and ack). When the rapid commit option is set by
2308 both the DHCPv4 client and the DHCPv4 server, the two-message exchange is used. Otherwise, the
2309 four-message exchange (discover, offer, request, and ack) is used. The two-message exchange
2310 provides faster client configuration. See
2311 <ulink url=
"https://tools.ietf.org/html/rfc4039">RFC
4039</ulink> for details.
2312 Defaults to true when
<varname>Anonymize=no
</varname> and neither
<varname>AllowList=
</varname>
2313 nor
<varname>DenyList=
</varname> is specified, and false otherwise.
</para>
2315 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2320 <term><varname>Anonymize=
</varname></term>
2322 <para>Takes a boolean. When true, the options sent to the DHCP server will follow the
2323 <ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink> (Anonymity Profiles for
2324 DHCP Clients) to minimize disclosure of identifying information. Defaults to false.
</para>
2326 <para>This option should only be set to true when
<varname>MACAddressPolicy=
</varname> is set
2327 to
<option>random
</option> (see
2328 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
2332 <varname>ClientIdentifier=mac
</varname>,
2333 <varname>RapidCommit=no
</varname>,
2334 <varname>SendHostname=no
</varname>,
2335 <varname>Use6RD=no
</varname>,
2336 <varname>UseCaptivePortal=no
</varname>,
2337 <varname>UseMTU=no
</varname>,
2338 <varname>UseNTP=no
</varname>,
2339 <varname>UseSIP=no
</varname>, and
2340 <varname>UseTimezone=no
</varname>
2341 are implied and these settings in the .network file are silently ignored. Also,
2342 <varname>Hostname=
</varname>,
2343 <varname>MUDURL=
</varname>,
2344 <varname>RequestAddress
</varname>,
2345 <varname>RequestOptions=
</varname>,
2346 <varname>SendOption=
</varname>,
2347 <varname>SendVendorOption=
</varname>,
2348 <varname>UserClass=
</varname>, and
2349 <varname>VendorClassIdentifier=
</varname>
2350 are silently ignored.
</para>
2352 <para>With this option enabled DHCP requests will mimic those generated by Microsoft
2353 Windows, in order to reduce the ability to fingerprint and recognize installations. This
2354 means DHCP request sizes will grow and lease data will be more comprehensive than normally,
2355 though most of the requested data is not actually used.
</para>
2357 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
2362 <term><varname>RequestOptions=
</varname></term>
2364 <para>Sets request options to be sent to the server in the DHCPv4 request options list. A
2365 whitespace-separated list of integers in the range
1…
254. Defaults to unset.
</para>
2367 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2372 <term><varname>SendOption=
</varname></term>
2374 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data
2375 type and data separated with a colon
2376 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2377 The option number must be an integer in the range
1…
254. The type takes one of
2378 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
2379 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
2380 string may be escaped using
2381 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2382 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2383 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
2385 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2390 <term><varname>SendVendorOption=
</varname></term>
2392 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data
2393 type and data separated with a colon
2394 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2395 The option number must be an integer in the range
1…
254. The type takes one of
2396 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
2397 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
2398 string may be escaped using
2399 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2400 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2401 then all options specified earlier are cleared. Defaults to unset.
</para>
2403 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2408 <term><varname>IPServiceType=
</varname></term>
2410 <para>Takes one of the special values
<literal>none
</literal>,
<literal>CS6
</literal>, or
2411 <literal>CS4
</literal>. When
<literal>none
</literal> no IP service type is set to the packet
2412 sent from the DHCPv4 client. When
<literal>CS6
</literal> (network control) or
2413 <literal>CS4
</literal> (realtime), the corresponding service type will be set. Defaults to
2414 <literal>CS6
</literal>.
</para>
2416 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2421 <term><varname>SocketPriority=
</varname></term>
2423 <para>The Linux socket option
<constant>SO_PRIORITY
</constant> applied to the raw IP socket used for
2424 initial DHCPv4 messages. Unset by default. Usual values range from
0 to
6.
2425 More details about
<constant>SO_PRIORITY
</constant> socket option in
2426 <citerefentry project='man-pages'
><refentrytitle>socket
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
2427 Can be used in conjunction with [VLAN] section
<varname>EgressQOSMaps=
</varname> setting of .netdev
2428 file to set the
802.1Q VLAN ethernet tagged header priority, see
2429 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2432 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
2436 <!-- How to use the DHCP lease -->
2439 <term><varname>Label=
</varname></term>
2441 <para>Specifies the label for the IPv4 address received from the DHCP server. The label must
2442 be a
7-bit ASCII string with a length of
1…
15 characters. Defaults to unset.
</para>
2444 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2449 <term><varname>UseDNS=
</varname></term>
2451 <para>When true (the default), the DNS servers received from the DHCP server will be used.
2454 <para>This corresponds to the
<option>nameserver
</option> option in
2455 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2458 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2463 <term><varname>RoutesToDNS=
</varname></term>
2465 <para>When true, the routes to the DNS servers received from the DHCP server will be
2466 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored. Defaults to
2469 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2474 <term><varname>UseNTP=
</varname></term>
2476 <para>When true (the default), the NTP servers received from the DHCP server will be used by
2477 <filename>systemd-timesyncd.service
</filename>.
</para>
2479 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
2484 <term><varname>RoutesToNTP=
</varname></term>
2486 <para>When true, the routes to the NTP servers received from the DHCP server will be
2487 configured. When
<varname>UseNTP=
</varname> is disabled, this setting is ignored. Defaults to
2490 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
2495 <term><varname>UseSIP=
</varname></term>
2497 <para>When true (the default), the SIP servers received from the DHCP server will be collected
2498 and made available to client programs.
</para>
2500 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2505 <term><varname>UseCaptivePortal=
</varname></term>
2507 <para>When true (the default), the captive portal advertised by the DHCP server will be recorded
2508 and made available to client programs and displayed in the
2509 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
2510 status output per-link.
</para>
2512 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
2517 <term><varname>UseMTU=
</varname></term>
2519 <para>When true, the interface maximum transmission unit from the DHCP server will be used on
2520 the current link. If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
2521 Defaults to false.
</para>
2523 <para>Note, some drivers will reset the interfaces if the MTU is changed. For such
2524 interfaces, please try to use
<varname>IgnoreCarrierLoss=
</varname> with a short timespan,
2525 e.g.
<literal>3 seconds
</literal>.
</para>
2527 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2532 <term><varname>UseHostname=
</varname></term>
2534 <para>When true (the default), the hostname received from the DHCP server will be set as the
2535 transient hostname of the system.
</para>
2537 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
2542 <term><varname>UseDomains=
</varname></term>
2544 <para>Takes a boolean, or the special value
<option>route
</option>. When true, the domain name
2545 received from the DHCP server will be used as DNS search domain over this link, similarly to the
2546 effect of the
<option>Domains=
</option> setting. If set to
<option>route
</option>, the domain name
2547 received from the DHCP server will be used for routing DNS queries only, but not for searching,
2548 similarly to the effect of the
<option>Domains=
</option> setting when the argument is prefixed with
2549 <literal>~
</literal>. Defaults to false.
</para>
2551 <para>It is recommended to enable this option only on trusted networks, as setting this
2552 affects resolution of all hostnames, in particular of single-label names. It is generally
2553 safer to use the supplied domain only as routing domain, rather than as search domain, in
2554 order to not have it affect local resolution of single-label names.
</para>
2556 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
2557 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2560 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2565 <term><varname>UseRoutes=
</varname></term>
2567 <para>When true (the default), the static routes will be requested from the DHCP server and
2568 added to the routing table with a metric of
1024, and a scope of
<option>global
</option>,
2569 <option>link
</option> or
<option>host
</option>, depending on the route's destination and
2570 gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the link's
2571 own address, the scope will be set to
<option>host
</option>. Otherwise if the gateway is null
2572 (a direct route), a
<option>link
</option> scope will be used. For anything else, scope
2573 defaults to
<option>global
</option>.
</para>
2575 <xi:include href=
"version-info.xml" xpointer=
"v215"/>
2580 <term><varname>RouteMetric=
</varname></term>
2582 <para>Set the routing metric for routes specified by the DHCP server (including the prefix
2583 route added for the specified prefix). Takes an unsigned integer in the range
0…
4294967295.
2584 Defaults to
1024.
</para>
2586 <xi:include href=
"version-info.xml" xpointer=
"v217"/>
2591 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
2593 <para>The table identifier for DHCP routes. Takes one of predefined names
2594 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
2595 defined in
<varname>RouteTable=
</varname> in
2596 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2597 or a number between
1…
4294967295.
</para>
2599 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
2600 used when this parameter is not specified.
</para>
2602 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
2607 <term><varname>RouteMTUBytes=
</varname></term>
2609 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further
2612 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2617 <term><varname>QuickAck=
</varname></term>
2619 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
2620 the acquired DHCPv4 lease. When unset, the kernel's default will be used.
</para>
2622 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
2627 <term><varname>InitialCongestionWindow=
</varname></term>
2629 <para>As in the [Route] section.
</para>
2631 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2636 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
2638 <para>As in the [Route] section.
</para>
2640 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2645 <term><varname>UseGateway=
</varname></term>
2647 <para>When true, and the DHCP server provides a Router option, the default gateway based on the
2648 router address will be configured. Defaults to unset, and the value specified with
2649 <varname>UseRoutes=
</varname> will be used.
</para>
2651 <para>Note, when the server provides both the Router and Classless Static Routes option, and
2652 <varname>UseRoutes=
</varname> is enabled, the Router option is always ignored regardless of this
2653 setting. See
<ulink url=
"https://datatracker.ietf.org/doc/html/rfc3442">RFC
3442</ulink>.
</para>
2655 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2660 <term><varname>UseTimezone=
</varname></term>
2661 <listitem><para>When true, the timezone received from the DHCP server will be set as timezone
2662 of the local system. Defaults to false.
</para>
2664 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
2668 <term><varname>Use6RD=
</varname></term>
2670 <para>When true, subnets of the received IPv6 prefix are assigned to downstream interfaces
2671 which enables
<varname>DHCPPrefixDelegation=
</varname>. See also
2672 <varname>DHCPPrefixDelegation=
</varname> in the [Network] section, the [DHCPPrefixDelegation]
2673 section, and
<ulink url=
"https://tools.ietf.org/html/rfc5969">RFC
5969</ulink>. Defaults to
2676 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2681 <term><varname>IPv6OnlyMode=
</varname></term>
2683 <para>When true, the DHCPv4 configuration will be delayed by the timespan provided by the DHCP
2684 server and skip to configure dynamic IPv4 network connectivity if IPv6 connectivity is provided
2685 within the timespan. See
<ulink url=
"https://tools.ietf.org/html/rfc8925">RFC
8925</ulink>.
2686 Defaults to false.
</para>
2688 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2693 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
2695 <para>Allows one to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease
2696 lifetime. Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal>. If
2697 specified, the acquired address never expires. Defaults to unset.
</para>
2699 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2703 <!-- How to communicate with the server -->
2706 <term><varname>RequestBroadcast=
</varname></term>
2708 <para>Request the server to use broadcast messages before the IP address has been configured.
2709 This is necessary for devices that cannot receive RAW packets, or that cannot receive packets
2710 at all before an IP address has been configured. On the other hand, this must not be enabled
2711 on networks where broadcasts are filtered out.
</para>
2713 <xi:include href=
"version-info.xml" xpointer=
"v216"/>
2718 <term><varname>MaxAttempts=
</varname></term>
2720 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
2721 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>. Note that the
2722 time between retries is increased exponentially, up to approximately one per minute, so the
2723 network will not be overloaded even if this number is high. The default is suitable in most
2724 circumstances.
</para>
2726 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2731 <term><varname>ListenPort=
</varname></term>
2733 <para>Set the port from which the DHCP client packets originate.
</para>
2735 <xi:include href=
"version-info.xml" xpointer=
"v233"/>
2740 <term><varname>DenyList=
</varname></term>
2742 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2743 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are rejected.
2744 Note that if
<varname>AllowList=
</varname> is configured then
<varname>DenyList=
</varname> is
2746 <para>Note that this filters only DHCP offers, so the filtering may not work when
2747 <varname>RapidCommit=
</varname> is enabled. See also
<varname>RapidCommit=
</varname> in the above.
2750 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2755 <term><varname>AllowList=
</varname></term>
2757 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2758 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are accepted.
2760 <para>Note that this filters only DHCP offers, so the filtering may not work when
2761 <varname>RapidCommit=
</varname> is enabled. See also
<varname>RapidCommit=
</varname> in the above.
2764 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2769 <term><varname>SendRelease=
</varname></term>
2771 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops. Defaults to
2774 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
2779 <term><varname>SendDecline=
</varname></term>
2781 <para>A boolean. When true,
<command>systemd-networkd
</command> performs IPv4 Duplicate
2782 Address Detection to the acquired address by the DHCPv4 client. If duplicate is detected,
2783 the DHCPv4 client rejects the address by sending a
<constant>DHCPDECLINE
</constant> packet to
2784 the DHCP server, and tries to obtain an IP address again. See
2785 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>. Defaults to false.
</para>
2787 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
2792 <term><varname>NetLabel=
</varname></term>
2794 <para>This applies the NetLabel for the addresses received with DHCP, like
2795 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
2796 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
2798 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2803 <term><varname>NFTSet=
</varname></term>
2805 <para>This applies the NFT set for the network configuration received with DHCP, like
2806 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
2807 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
2808 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
2809 <literal>ipv4_addr
</literal>.
</para>
2811 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2818 <title>[DHCPv6] Section Options
</title>
2820 <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
2821 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
2824 <variablelist class='network-directives'
>
2826 <!-- DHCP packet contents -->
2829 <term><varname>MUDURL=
</varname></term>
2830 <term><varname>IAID=
</varname></term>
2831 <term><varname>DUIDType=
</varname></term>
2832 <term><varname>DUIDRawData=
</varname></term>
2833 <term><varname>RequestOptions=
</varname></term>
2835 <para>As in the [DHCPv4] section.
</para>
2837 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2842 <term><varname>SendOption=
</varname></term>
2844 <para>As in the [DHCPv4] section, however because DHCPv6 uses
16-bit fields to store option
2845 numbers, the option number is an integer in the range
1…
65536.
</para>
2847 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2852 <term><varname>SendVendorOption=
</varname></term>
2854 <para>Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier,
2855 DHCP option number, data type, and data separated with a colon
2856 (
<literal><replaceable>enterprise identifier
</replaceable>:
<replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2857 Enterprise identifier is an unsigned integer in the range
1…
4294967294. The option number
2858 must be an integer in the range
1…
254. Data type takes one of
<literal>uint8
</literal>,
2859 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
2860 <literal>ipv6address
</literal>, or
<literal>string
</literal>. Special characters in the data
2861 string may be escaped using
2862 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2863 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2864 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
2866 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2871 <term><varname>UserClass=
</varname></term>
2873 <para>A DHCPv6 client can use User Class option to identify the type or category of user or
2874 applications it represents. The information contained in this option is a string that
2875 represents the user class of which the client is a member. Each class sets an identifying
2876 string of information to be used by the DHCP service to classify clients. Special characters
2877 in the data string may be escaped using
2878 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2879 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2880 specified, then all options specified earlier are cleared. Takes a whitespace-separated list
2881 of strings. Note that currently
<constant>NUL
</constant> bytes are not allowed.
</para>
2883 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2888 <term><varname>VendorClass=
</varname></term>
2890 <para>A DHCPv6 client can use VendorClass option to identify the vendor that manufactured the
2891 hardware on which the client is running. The information contained in the data area of this
2892 option is contained in one or more opaque fields that identify details of the hardware
2893 configuration. Takes a whitespace-separated list of strings.
</para>
2895 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
2900 <term><varname>PrefixDelegationHint=
</varname></term>
2902 <para>Takes an IPv6 address with prefix length in the same format as the
2903 <varname>Address=
</varname> in the [Network] section. The DHCPv6 client will include a prefix
2904 hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
2905 1…
128. Defaults to unset.
</para>
2907 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
2912 <term><varname>RapidCommit=
</varname></term>
2914 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server
2915 through a rapid two-message exchange (solicit and reply). When the rapid commit option is set by
2916 both the DHCPv6 client and the DHCPv6 server, the two-message exchange is used. Otherwise, the
2917 four-message exchange (solicit, advertise, request, and reply) is used. The two-message exchange
2918 provides faster client configuration. See
2919 <ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
2920 Defaults to true, and the two-message exchange will be used if the server support it.
</para>
2922 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
2927 <term><varname>SendHostname=
</varname></term>
2929 <para>When true (the default), the machine's hostname (or the value specified with
2930 <varname>Hostname=
</varname>, described below) will be sent to the DHCPv6 server. Note that the
2931 hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and be
2932 formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option
2935 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2940 <term><varname>Hostname=
</varname></term>
2942 <para>Use this value for the hostname which is sent to the DHCPv6 server, instead of machine's
2943 hostname. Note that the specified hostname must consist only of
7-bit ASCII lower-case
2944 characters and no spaces or dots, and be formatted as a valid DNS domain name.
</para>
2946 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
2950 <!-- How to use the DHCP lease -->
2953 <term><varname>UseAddress=
</varname></term>
2955 <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
2958 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
2963 <term><varname>UseCaptivePortal=
</varname></term>
2965 <para>When true (the default), the captive portal advertised by the DHCPv6 server will be recorded
2966 and made available to client programs and displayed in the
2967 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
2968 status output per-link.
</para>
2970 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
2975 <term><varname>UseDelegatedPrefix=
</varname></term>
2977 <para>When true (the default), the client will request the DHCPv6 server to delegate
2978 prefixes. If the server provides prefixes to be delegated, then subnets of the prefixes are
2979 assigned to the interfaces that have
<varname>DHCPPrefixDelegation=yes
</varname>.
2980 See also the
<varname>DHCPPrefixDelegation=
</varname> setting in the [Network] section,
2981 settings in the [DHCPPrefixDelegation] section, and
2982 <ulink url=
"https://www.rfc-editor.org/rfc/rfc8415.html#section-6.3">RFC
8415</ulink>.
2985 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
2990 <term><varname>UseDNS=
</varname></term>
2991 <term><varname>UseNTP=
</varname></term>
2992 <term><varname>UseHostname=
</varname></term>
2993 <term><varname>UseDomains=
</varname></term>
2994 <term><varname>NetLabel=
</varname></term>
2995 <term><varname>SendRelease=
</varname></term>
2997 <para>As in the [DHCPv4] section.
</para>
2999 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
3004 <term><varname>NFTSet=
</varname></term>
3006 <para>This applies the NFT set for the network configuration received with DHCP, like
3007 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
3008 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal>
3009 or
<literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
3010 <literal>ipv6_addr
</literal>.
</para>
3012 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3016 <!-- How to communicate with the server -->
3019 <term><varname>WithoutRA=
</varname></term>
3021 <para>Allows DHCPv6 client to start without router advertisements's
3022 <literal>managed
</literal> or
<literal>other configuration
</literal> flag. Takes one of
3023 <literal>no
</literal>,
<literal>solicit
</literal>, or
3024 <literal>information-request
</literal>. If this is not specified,
3025 <literal>solicit
</literal> is used when
<varname>DHCPPrefixDelegation=
</varname> is enabled
3026 and
<varname>UplinkInterface=:self
</varname> is specified in the [DHCPPrefixDelegation]
3027 section. Otherwise, defaults to
<literal>no
</literal>, and the DHCPv6 client will be started
3028 when an RA is received. See also the
<varname>DHCPv6Client=
</varname> setting in the
3029 [IPv6AcceptRA] section.
</para>
3031 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3038 <title>[DHCPPrefixDelegation] Section Options
</title>
3039 <para>The [DHCPPrefixDelegation] section configures subnet prefixes of the delegated prefixes
3040 acquired by a DHCPv6 client or by a DHCPv4 client through the
6RD option on another interface.
3041 The settings in this section are used only when the
<varname>DHCPPrefixDelegation=
</varname>
3042 setting in the [Network] section is enabled.
</para>
3044 <variablelist class='network-directives'
>
3046 <term><varname>UplinkInterface=
</varname></term>
3048 <para>Specifies the name or the index of the uplink interface, or one of the special values
3049 <literal>:self
</literal> and
<literal>:auto
</literal>. When
<literal>:self
</literal>, the
3050 interface itself is considered the uplink interface, and
3051 <varname>WithoutRA=solicit
</varname> is implied if the setting is not explicitly specified.
3052 When
<literal>:auto
</literal>, the first link which acquired prefixes to be delegated from
3053 the DHCPv6 or DHCPv4 server is selected. Defaults to
<literal>:auto
</literal>.
</para>
3055 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3060 <term><varname>SubnetId=
</varname></term>
3062 <para>Configure a specific subnet ID on the interface from a (previously) received prefix
3063 delegation. You can either set
"auto" (the default) or a specific subnet ID (as defined in
3064 <ulink url=
"https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC
4291</ulink>, section
3065 2.5.4), in which case the allowed value is hexadecimal, from
0 to
0x7fffffffffffffff
3068 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3073 <term><varname>Announce=
</varname></term>
3075 <para>Takes a boolean. When enabled, and
<varname>IPv6SendRA=
</varname> in [Network] section
3076 is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
3077 This setting will be ignored when the
<varname>DHCPPrefixDelegation=
</varname> setting is
3078 enabled on the upstream interface. Defaults to yes.
</para>
3080 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
3085 <term><varname>Assign=
</varname></term>
3087 <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
3088 are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
3089 interface), the EUI-
64 algorithm will be used by default to form an interface identifier from
3090 the delegated prefixes. See also
<varname>Token=
</varname> setting below. Defaults to yes.
3093 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3098 <term><varname>Token=
</varname></term>
3100 <para>Specifies an optional address generation mode for assigning an address in each
3101 delegated prefix. This accepts the same syntax as
<varname>Token=
</varname> in the
3102 [IPv6AcceptRA] section. If
<varname>Assign=
</varname> is set to false, then this setting will
3103 be ignored. Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
3105 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3110 <term><varname>ManageTemporaryAddress=
</varname></term>
3112 <para>As in the [Address] section, but defaults to true.
</para>
3114 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3119 <term><varname>RouteMetric=
</varname></term>
3121 <para>The metric of the route to the delegated prefix subnet. Takes an unsigned integer in
3122 the range
0…
4294967295. When set to
0, the kernel's default value is used. Defaults to
256.
3125 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3130 <term><varname>NetLabel=
</varname></term>
3132 <para>This applies the NetLabel for the addresses received with DHCP, like
3133 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
3134 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
3136 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
3141 <term><varname>NFTSet=
</varname></term>
3143 <para>This applies the NFT set for the network configuration received with DHCP, like
3144 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
3145 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
3146 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
3147 <literal>ipv6_addr
</literal>.
</para>
3149 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3156 <title>[IPv6AcceptRA] Section Options
</title>
3157 <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
3158 with the
<varname>IPv6AcceptRA=
</varname> setting described above:
</para>
3160 <variablelist class='network-directives'
>
3162 <term><varname>Token=
</varname></term>
3164 <para>Specifies an optional address generation mode for the Stateless Address
3165 Autoconfiguration (SLAAC). The following values are supported:
</para>
3169 <term><option>eui64
</option></term>
3172 The EUI-
64 algorithm will be used to generate an address for that prefix. Only
3173 supported by Ethernet or InfiniBand interfaces.
3176 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3180 <term><option>static:
<replaceable>ADDRESS
</replaceable></option></term>
3183 An IPv6 address must be specified after a colon (
<literal>:
</literal>), and the
3184 lower bits of the supplied address are combined with the upper bits of a prefix
3185 received in a Router Advertisement (RA) message to form a complete address. Note
3186 that if multiple prefixes are received in an RA message, or in multiple RA messages,
3187 addresses will be formed from each of them using the supplied address. This mode
3188 implements SLAAC but uses a static interface identifier instead of an identifier
3189 generated by using the EUI-
64 algorithm. Because the interface identifier is static,
3190 if Duplicate Address Detection detects that the computed address is a duplicate
3191 (in use by another node on the link), then this mode will fail to provide an address
3192 for that prefix. If an IPv6 address without mode is specified, then
3193 <literal>static
</literal> mode is assumed.
3196 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3200 <term><option>prefixstable[:
<replaceable>ADDRESS
</replaceable>][,
<replaceable>UUID
</replaceable>]
</option></term>
3203 The algorithm specified in
3204 <ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink> will be used to
3205 generate interface identifiers. This mode can optionally take an IPv6 address
3206 separated with a colon (
<literal>:
</literal>). If an IPv6 address is specified,
3207 then an interface identifier is generated only when a prefix received in an RA
3208 message matches the supplied address.
3211 This mode can also optionally take a non-null UUID in the format which
3212 <function>sd_id128_from_string()
</function> accepts, e.g.
3213 <literal>86b123b969ba4b7eb8b3d8605123525a
</literal> or
3214 <literal>86b123b9-
69ba-
4b7e-b8b3-d8605123525a
</literal>. If a UUID is specified, the
3215 value is used as the secret key to generate interface identifiers. If not specified,
3216 then an application specific ID generated with the system's machine-ID will be used
3217 as the secret key. See
3218 <citerefentry><refentrytitle>sd-id128
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
3219 <citerefentry><refentrytitle>sd_id128_from_string
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
3221 <citerefentry><refentrytitle>sd_id128_get_machine
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
3224 Note that the
<literal>prefixstable
</literal> algorithm uses both the interface
3225 name and MAC address as input to the hash to compute the interface identifier, so
3226 if either of those are changed the resulting interface identifier (and address)
3227 will be changed, even if the prefix received in the RA message has not been
3231 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3236 <para>If no address generation mode is specified (which is the default), or a received
3237 prefix does not match any of the addresses provided in
<literal>prefixstable
</literal>
3238 mode, then the EUI-
64 algorithm will be used for Ethernet or InfiniBand interfaces,
3239 otherwise
<literal>prefixstable
</literal> will be used to form an interface identifier for
3242 <para>This setting can be specified multiple times. If an empty string is assigned, then
3243 the all previous assignments are cleared.
</para>
3246 <programlisting>Token=eui64
3248 Token=static:::
1a:
2b:
3c:
4d
3250 Token=prefixstable:
2002:da8:
1::
</programlisting></para>
3252 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3257 <term><varname>UseDNS=
</varname></term>
3259 <para>When true (the default), the DNS servers received in the Router Advertisement will be used.
</para>
3261 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
3262 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3264 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
3269 <term><varname>UseDomains=
</varname></term>
3271 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
3272 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link,
3273 similarly to the effect of the
<option>Domains=
</option> setting. If set to
3274 <literal>route
</literal>, the domain name received via IPv6 RA will be used for routing DNS queries
3275 only, but not for searching, similarly to the effect of the
<option>Domains=
</option> setting when
3276 the argument is prefixed with
<literal>~
</literal>. Defaults to false.
</para>
3278 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
3279 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
3280 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
3281 single-label names.
</para>
3283 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
3284 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3286 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
3291 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
3293 <para>The table identifier for the routes received in the Router Advertisement. Takes one of
3294 predefined names
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
3295 and names defined in
<varname>RouteTable=
</varname> in
3296 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3297 or a number between
1…
4294967295.
</para>
3299 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
3300 used when this parameter is not specified.
</para>
3302 <xi:include href=
"version-info.xml" xpointer=
"v232"/>
3307 <term><varname>RouteMetric=
</varname></term>
3309 <para>Set the routing metric for the routes received in the Router Advertisement. Takes an unsigned
3310 integer in the range
0…
4294967295, or three unsigned integer separated with
<literal>:
</literal>,
3311 in that case the first one is used when the router preference is high, the second is for medium
3312 preference, and the last is for low preference
3313 (
<literal><replaceable>high
</replaceable>:
<replaceable>medium
</replaceable>:
<replaceable>low
</replaceable></literal>).
3314 Defaults to
<literal>512:
1024:
2048</literal>.
</para>
3316 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3321 <term><varname>QuickAck=
</varname></term>
3323 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
3324 the received RAs. When unset, the kernel's default will be used.
</para>
3326 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
3331 <term><varname>UseMTU=
</varname></term>
3333 <para>Takes a boolean. When true, the MTU received in the Router Advertisement will be
3334 used. Defaults to true.
</para>
3336 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3341 <term><varname>UseHopLimit=
</varname></term>
3343 <para>Takes a boolean. When true, the hop limit received in the Router Advertisement will be set to routes
3344 configured based on the advertisement. See also
<varname>IPv6HopLimit=
</varname>. Defaults to true.
</para>
3346 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3351 <term><varname>UseRetransmissionTime=
</varname></term>
3353 <para>Takes a boolean. When true, the retransmission time received in the Router Advertisement will be set
3354 on the interface receiving the advertisement. It is used as the time between retransmissions of Neighbor
3355 Solicitation messages to a neighbor when resolving the address or when probing the reachability of a neighbor.
3356 Defaults to true.
</para>
3358 <xi:include href=
"version-info.xml" xpointer=
"v256"/>
3363 <term><varname>UseICMP6RateLimit=
</varname></term>
3365 <para>Takes a boolean. When true, the ICMP6 rate limit received in the Router Advertisement will be set to ICMP6
3366 rate limit based on the advertisement. Defaults to true.
</para>
3368 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3373 <term><varname>UseGateway=
</varname></term>
3375 <para>When true (the default), the router address will be configured as the default gateway.
3378 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3383 <term><varname>UseRoutePrefix=
</varname></term>
3385 <para>When true (the default), the routes corresponding to the route prefixes received in
3386 the Router Advertisement will be configured.
</para>
3388 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
3393 <term><varname>UseCaptivePortal=
</varname></term>
3395 <para>When true (the default), the captive portal received in the Router Advertisement will be recorded
3396 and made available to client programs and displayed in the
3397 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
3398 status output per-link.
</para>
3400 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
3405 <term><varname>UsePREF64=
</varname></term>
3407 <para>When true, the IPv6 PREF64 (or NAT64) prefixes received in the Router Advertisement will be
3408 recorded and made available to client programs and displayed in the
3409 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
3410 status output per-link. See
<ulink url=
"https://tools.ietf.org/html/rfc8781">RFC
8781</ulink>.
3411 Defaults to false.
</para>
3413 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3418 <term><varname>UseAutonomousPrefix=
</varname></term>
3420 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
3421 precedence over any statically configured ones.
</para>
3423 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
3428 <term><varname>UseOnLinkPrefix=
</varname></term>
3430 <para>When true (the default), the onlink prefix received in the Router Advertisement will be
3431 used and takes precedence over any statically configured ones.
</para>
3433 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
3438 <term><varname>RouterDenyList=
</varname></term>
3440 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
3441 take a prefix length after
<literal>/
</literal>. Any information advertised by the listed
3442 router is ignored.
</para>
3444 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3449 <term><varname>RouterAllowList=
</varname></term>
3451 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
3452 take a prefix length after
<literal>/
</literal>. Only information advertised by the listed
3453 router is accepted. Note that if
<varname>RouterAllowList=
</varname> is configured then
3454 <varname>RouterDenyList=
</varname> is ignored.
</para>
3456 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3461 <term><varname>PrefixDenyList=
</varname></term>
3463 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
3464 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
3465 in the list are ignored.
</para>
3467 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3472 <term><varname>PrefixAllowList=
</varname></term>
3474 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
3475 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
3476 in the list are allowed. Note that if
<varname>PrefixAllowList=
</varname> is configured
3477 then
<varname>PrefixDenyList=
</varname> is ignored.
</para>
3479 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3484 <term><varname>RouteDenyList=
</varname></term>
3486 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
3487 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
3488 advertisements in the list are ignored.
</para>
3490 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3495 <term><varname>RouteAllowList=
</varname></term>
3497 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
3498 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
3499 advertisements in the list are allowed. Note that if
<varname>RouteAllowList=
</varname> is
3500 configured then
<varname>RouteDenyList=
</varname> is ignored.
</para>
3502 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
3507 <term><varname>DHCPv6Client=
</varname></term>
3509 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true, the
3510 DHCPv6 client will be started in
<literal>solicit
</literal> mode if the RA has the
3511 <literal>managed
</literal> flag or
<literal>information-request
</literal> mode if the RA
3512 lacks the
<literal>managed
</literal> flag but has the
3513 <literal>other configuration
</literal> flag. If set to
<literal>always
</literal>, the
3514 DHCPv6 client will be started in
<literal>solicit
</literal> mode when an RA is received,
3515 even if neither the
<literal>managed
</literal> nor the
3516 <literal>other configuration
</literal> flag is set in the RA. This will be ignored when
3517 <varname>WithoutRA=
</varname> in the [DHCPv6] section is enabled, or
3518 <varname>UplinkInterface=:self
</varname> in the [DHCPPrefixDelegation] section is
3519 specified. Defaults to true.
</para>
3521 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3526 <term><varname>NetLabel=
</varname></term>
3528 <para>This applies the NetLabel for the addresses received with RA, like
3529 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
3530 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
3532 <xi:include href=
"version-info.xml" xpointer=
"v252"/>
3537 <term><varname>NFTSet=
</varname></term>
3539 <para>This applies the NFT set for the network configuration received with RA, like
3540 <varname>NFTSet=
</varname> in [Address] section applies it to static configuration. See
3541 <varname>NFTSet=
</varname> in [Address] section for more details. For
<literal>address
</literal> or
3542 <literal>prefix
</literal> source types, the type of the element used in the NFT filter must be
3543 <literal>ipv6_addr
</literal>.
</para>
3545 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3552 <title>[DHCPServer] Section Options
</title>
3553 <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
3554 <varname>DHCPServer=
</varname> option described above:
</para>
3556 <variablelist class='network-directives'
>
3559 <term><varname>ServerAddress=
</varname></term>
3561 <para>Specifies the server address for the DHCP server. Takes an IPv4 address with prefix length
3562 separated with a slash, e.g.
<literal>192.168.0.1/
24</literal>. Defaults to unset, and one of
3563 static IPv4 addresses configured in [Network] or [Address] section will be automatically selected.
3564 This setting may be useful when the interface on which the DHCP server is running has multiple
3565 static IPv4 addresses.
</para>
3566 <para>This implies
<varname>Address=
</varname> in [Network] or [Address] section with the same
3567 address and prefix length. That is,
3568 <programlisting>[Network]
3570 Address=
192.168.0.1/
24
3571 Address=
192.168.0.2/
24
3573 ServerAddress=
192.168.0.1/
24</programlisting>
3575 <programlisting>[Network]
3578 Address=
192.168.0.1/
24
3580 Address=
192.168.0.2/
24
3582 ServerAddress=
192.168.0.1/
24</programlisting>
3583 are equivalent to the following.
3584 <programlisting>[Network]
3586 Address=
192.168.0.2/
24
3588 ServerAddress=
192.168.0.1/
24</programlisting>
3590 <para>Since version
255, like the
<varname>Address=
</varname> setting in [Network] or [Address]
3591 section, this also supports a null address, e.g.
<literal>0.0.0.0/
24</literal>, and an unused
3592 address will be automatically selected. For more details about the automatic address selection,
3593 see
<varname>Address=
</varname> setting in [Network] section in the above.
</para>
3595 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3600 <term><varname>PoolOffset=
</varname></term>
3601 <term><varname>PoolSize=
</varname></term>
3603 <listitem><para>Configures the pool of addresses to hand out. The pool
3604 is a contiguous sequence of IP addresses in the subnet configured for
3605 the server address, which does not include the subnet nor the broadcast
3606 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
3607 from the start of subnet, or zero to use the default value.
3608 <varname>PoolSize=
</varname> takes the number of IP addresses in the
3609 pool or zero to use the default value. By default, the pool starts at
3610 the first address after the subnet address and takes up the rest of
3611 the subnet, excluding the broadcast address. If the pool includes
3612 the server address (the default), this is reserved and not handed
3613 out to clients.
</para>
3615 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3619 <term><varname>DefaultLeaseTimeSec=
</varname></term>
3620 <term><varname>MaxLeaseTimeSec=
</varname></term>
3622 <listitem><para>Control the default and maximum DHCP lease
3623 time to pass to clients. These settings take time values in seconds or
3624 another common time unit, depending on the suffix. The default
3625 lease time is used for clients that did not ask for a specific
3626 lease time. If a client asks for a lease time longer than the
3627 maximum lease time, it is automatically shortened to the
3628 specified time. The default lease time defaults to
1h, the
3629 maximum lease time to
12h. Shorter lease times are beneficial
3630 if the configuration data in DHCP leases changes frequently
3631 and clients shall learn the new settings with shorter
3632 latencies. Longer lease times reduce the generated DHCP
3633 network traffic.
</para>
3635 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3639 <term><varname>UplinkInterface=
</varname></term>
3640 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
3641 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS, NTP, or SIP
3642 servers is enabled but no servers are specified, the servers configured in the uplink interface
3643 will be emitted. When
<literal>:auto
</literal>, the link which has a default gateway with the
3644 highest priority will be automatically selected. When
<literal>:none
</literal>, no uplink
3645 interface will be selected. Defaults to
<literal>:auto
</literal>.
</para>
3647 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3651 <term><varname>EmitDNS=
</varname></term>
3652 <term><varname>DNS=
</varname></term>
3654 <listitem><para><varname>EmitDNS=
</varname> takes a boolean. Configures whether the DHCP leases
3655 handed out to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
3656 The DNS servers to pass to clients may be configured with the
<varname>DNS=
</varname> option,
3657 which takes a list of IPv4 addresses, or special value
<literal>_server_address
</literal> which
3658 will be converted to the address used by the DHCP server.
</para>
3660 <para>If the
<varname>EmitDNS=
</varname> option is enabled but no servers configured, the
3661 servers are automatically propagated from an
"uplink" interface that has appropriate servers
3662 set. The
"uplink" interface is determined by the default route of the system with the highest
3663 priority. Note that this information is acquired at the time the lease is handed out, and does
3664 not take uplink interfaces into account that acquire DNS server information at a later point.
3665 If no suitable uplink interface is found the DNS server data from
3666 <filename>/etc/resolv.conf
</filename> is used. Also, note that the leases are not refreshed if
3667 the uplink network configuration changes. To ensure clients regularly acquire the most current
3668 uplink DNS server information, it is thus advisable to shorten the DHCP lease time via
3669 <varname>MaxLeaseTimeSec=
</varname> described above.
</para>
3671 <para>This setting can be specified multiple times. If an empty string is specified, then all
3672 DNS servers specified earlier are cleared.
</para>
3674 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3678 <term><varname>EmitNTP=
</varname></term>
3679 <term><varname>NTP=
</varname></term>
3680 <term><varname>EmitSIP=
</varname></term>
3681 <term><varname>SIP=
</varname></term>
3682 <term><varname>EmitPOP3=
</varname></term>
3683 <term><varname>POP3=
</varname></term>
3684 <term><varname>EmitSMTP=
</varname></term>
3685 <term><varname>SMTP=
</varname></term>
3686 <term><varname>EmitLPR=
</varname></term>
3687 <term><varname>LPR=
</varname></term>
3689 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname> settings
3690 described above, these settings configure whether and what server information for the indicate
3691 protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
3692 defaults apply as for
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname>.
</para>
3694 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3698 <term><varname>EmitRouter=
</varname></term>
3699 <term><varname>Router=
</varname></term>
3701 <listitem><para>The
<varname>EmitRouter=
</varname> setting takes a boolean value, and configures
3702 whether the DHCP lease should contain the router option. The
<varname>Router=
</varname> setting
3703 takes an IPv4 address, and configures the router address to be emitted. When the
3704 <varname>Router=
</varname> setting is not specified, then the server address will be used for
3705 the router option. When the
<varname>EmitRouter=
</varname> setting is disabled, the
3706 <varname>Router=
</varname> setting will be ignored. The
<varname>EmitRouter=
</varname> setting
3707 defaults to true, and the
<varname>Router=
</varname> setting defaults to unset.
3710 <xi:include href=
"version-info.xml" xpointer=
"v230"/></listitem>
3714 <term><varname>EmitTimezone=
</varname></term>
3715 <term><varname>Timezone=
</varname></term>
3717 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
3718 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
3719 <varname>Timezone=
</varname> setting takes a timezone string
3720 (such as
<literal>Europe/Berlin
</literal> or
3721 <literal>UTC
</literal>) to pass to clients. If no explicit
3722 timezone is set, the system timezone of the local host is
3723 propagated, as determined by the
3724 <filename>/etc/localtime
</filename> symlink.
</para>
3726 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
3730 <term><varname>BootServerAddress=
</varname></term>
3733 <para>Takes an IPv4 address of the boot server used by e.g. PXE boot systems. When specified, this
3734 address is sent in the
<option>siaddr
</option> field of the DHCP message header. See
<ulink
3735 url=
"https://www.rfc-editor.org/rfc/rfc2131.html">RFC
2131</ulink> for more details. Defaults to
3738 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3743 <term><varname>BootServerName=
</varname></term>
3746 <para>Takes a name of the boot server used by e.g. PXE boot systems. When specified, this name is
3747 sent in the DHCP option
66 (
"TFTP server name"). See
<ulink
3748 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
3751 <para>Note that typically setting one of
<varname>BootServerName=
</varname> or
3752 <varname>BootServerAddress=
</varname> is sufficient, but both can be set too, if desired.
</para>
3754 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3759 <term><varname>BootFilename=
</varname></term>
3762 <para>Takes a path or URL to a file loaded by e.g. a PXE boot loader. When specified, this path is
3763 sent in the DHCP option
67 (
"Bootfile name"). See
<ulink
3764 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
3767 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
3772 <term><varname>IPv6OnlyPreferredSec=
</varname></term>
3775 <para>Takes a timespan. Controls the
3776 <ulink url=
"https://tools.ietf.org/html/rfc8925">RFC
8925</ulink> IPv6-Only Preferred option.
3777 Specifies the DHCPv4 option to indicate that a host supports an IPv6-only mode and is willing to
3778 forgo obtaining an IPv4 address if the network provides IPv6 connectivity. Defaults to unset, and
3779 not send the option. The minimum allowed value is
300 seconds.
</para>
3781 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3786 <term><varname>SendOption=
</varname></term>
3788 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
3789 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
3790 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
3791 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
3792 <literal>string
</literal>. Special characters in the data string may be escaped using
3793 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
3794 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
3795 then all options specified earlier are cleared. Defaults to unset.
</para>
3797 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
3802 <term><varname>SendVendorOption=
</varname></term>
3804 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
3805 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
3806 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
3807 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
3808 <literal>string
</literal>. Special characters in the data string may be escaped using
3809 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
3810 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
3811 then all options specified earlier are cleared. Defaults to unset.
</para>
3813 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
3817 <term><varname>BindToInterface=
</varname></term>
3819 <para>Takes a boolean value. When
<literal>yes
</literal>, DHCP server socket will be bound
3820 to its network interface and all socket communication will be restricted to this interface.
3821 Defaults to
<literal>yes
</literal>, except if
<varname>RelayTarget=
</varname> is used (see below),
3822 in which case it defaults to
<literal>no
</literal>.
</para>
3824 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3828 <term><varname>RelayTarget=
</varname></term>
3830 <para>Takes an IPv4 address, which must be in the format described in
3831 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
3832 Turns this DHCP server into a DHCP relay agent. See
<ulink url=
"https://tools.ietf.org/html/rfc1542">RFC
1542</ulink>.
3833 The address is the address of DHCP server or another relay agent to forward DHCP messages to and from.
</para>
3835 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3839 <term><varname>RelayAgentCircuitId=
</varname></term>
3841 <para>Specifies value for Agent Circuit ID suboption of Relay Agent Information option.
3842 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
3843 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
3844 Defaults to unset (means no Agent Circuit ID suboption is generated).
3845 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3847 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3851 <term><varname>RelayAgentRemoteId=
</varname></term>
3853 <para>Specifies value for Agent Remote ID suboption of Relay Agent Information option.
3854 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
3855 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
3856 Defaults to unset (means no Agent Remote ID suboption is generated).
3857 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3859 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
3864 <term><varname>RapidCommit=
</varname></term>
3866 <para>Takes a boolean. When true, the server supports
3867 <ulink url=
"https://datatracker.ietf.org/doc/html/rfc4039">RFC
4039</ulink>. When a client sends
3868 a DHCPDISCOVER message with the Rapid Commit option to the server, then the server will reply with
3869 a DHCPACK message to the client, instead of DHCPOFFER. Defaults to true.
</para>
3871 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3879 <title>[DHCPServerStaticLease] Section Options
</title>
3880 <para>The
<literal>[DHCPServerStaticLease]
</literal> section configures a static DHCP lease to assign a
3881 fixed IPv4 address to a specific device based on its MAC address. This section can be specified multiple
3884 <variablelist class='network-directives'
>
3886 <term><varname>MACAddress=
</varname></term>
3888 <listitem><para>The hardware address of a device to match. This key is mandatory.
</para>
3890 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3894 <term><varname>Address=
</varname></term>
3896 <listitem><para>The IPv4 address that should be assigned to the device that was matched with
3897 <varname>MACAddress=
</varname>. This key is mandatory.
</para>
3899 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
3905 <title>[IPv6SendRA] Section Options
</title>
3906 <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
3907 to act as a router, if enabled via the
<varname>IPv6SendRA=
</varname> option described above. IPv6
3908 network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
3911 <variablelist class='network-directives'
>
3914 <term><varname>Managed=
</varname></term>
3915 <term><varname>OtherInformation=
</varname></term>
3917 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
3918 addresses on the network link when
<varname>Managed=
</varname>
3919 is set to
<literal>true
</literal> or if only additional network
3920 information can be obtained via DHCPv6 for the network link when
3921 <varname>OtherInformation=
</varname> is set to
3922 <literal>true
</literal>. Both settings default to
3923 <literal>false
</literal>, which means that a DHCPv6 server is not being
3926 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3930 <term><varname>RouterLifetimeSec=
</varname></term>
3932 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. The value must be
0
3933 seconds, or between
4 seconds and
9000 seconds. When set to
0, the host is not acting as a router.
3934 Defaults to
1800 seconds (
30 minutes).
</para>
3936 <xi:include href=
"version-info.xml" xpointer=
"v235"/>
3941 <term><varname>RetransmitSec=
</varname></term>
3943 <listitem><para>Takes a timespan. Configures the retransmit time, used by clients to retransmit Neighbor
3944 Solicitation messages on address resolution and the Neighbor Unreachability Detection algorithm.
3945 An integer the default unit of seconds, in the range
0…
4294967295 msec. Defaults to
0.
</para>
3947 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3952 <term><varname>RouterPreference=
</varname></term>
3954 <listitem><para>Configures IPv6 router preference if
3955 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
3956 <literal>high
</literal>,
<literal>medium
</literal> and
3957 <literal>low
</literal>, with
<literal>normal
</literal> and
3958 <literal>default
</literal> added as synonyms for
3959 <literal>medium
</literal> just to make configuration easier. See
3960 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
3961 for details. Defaults to
<literal>medium
</literal>.
</para>
3963 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
3967 <term><varname>HopLimit=
</varname></term>
3969 <para>Configures hop limit. Takes an integer in the range
0…
255. See also
3970 <varname>IPv6HopLimit=
</varname>.
</para>
3972 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
3977 <term><varname>UplinkInterface=
</varname></term>
3978 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
3979 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS servers or
3980 search domains is enabled but no servers are specified, the servers configured in the uplink
3981 interface will be emitted. When
<literal>:auto
</literal>, the value specified to the same
3982 setting in the [DHCPPrefixDelegation] section will be used if
3983 <varname>DHCPPrefixDelegation=
</varname> is enabled, otherwise the link which has a default
3984 gateway with the highest priority will be automatically selected. When
<literal>:none
</literal>,
3985 no uplink interface will be selected. Defaults to
<literal>:auto
</literal>.
</para>
3987 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
3991 <term><varname>EmitDNS=
</varname></term>
3992 <term><varname>DNS=
</varname></term>
3994 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
3995 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is true.
3996 <varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that case
3997 the IPv6 link-local address is distributed. If
<varname>DNS=
</varname> is empty, DNS servers are
3998 read from the [Network] section. If the [Network] section does not contain any DNS servers
3999 either, DNS servers from the uplink interface specified in
<varname>UplinkInterface=
</varname>
4000 will be used. When
<varname>EmitDNS=
</varname> is false, no DNS server information is sent in
4001 Router Advertisement messages.
<varname>EmitDNS=
</varname> defaults to true.
</para>
4003 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
4007 <term><varname>EmitDomains=
</varname></term>
4008 <term><varname>Domains=
</varname></term>
4010 <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
4011 <varname>EmitDomains=
</varname> is true. If
<varname>Domains=
</varname> is empty, DNS search
4012 domains are read from the [Network] section. If the [Network] section does not contain any DNS
4013 search domains either, DNS search domains from the uplink interface specified in
4014 <varname>UplinkInterface=
</varname> will be used. When
<varname>EmitDomains=
</varname> is false,
4015 no DNS search domain information is sent in Router Advertisement messages.
4016 <varname>EmitDomains=
</varname> defaults to true.
</para>
4018 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
4022 <term><varname>DNSLifetimeSec=
</varname></term>
4024 <listitem><para>Lifetime in seconds for the DNS server addresses listed in
4025 <varname>DNS=
</varname> and search domains listed in
<varname>Domains=
</varname>. Defaults to
4026 3600 seconds (one hour).
</para>
4028 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
4032 <term><varname>HomeAgent=
</varname></term>
4034 <listitem><para>Takes a boolean. Specifies that IPv6 router advertisements which indicates to hosts that
4035 the router acts as a Home Agent and includes a Home Agent Option. Defaults to false. See
4036 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink> for further details.
</para>
4038 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
4043 <term><varname>HomeAgentLifetimeSec=
</varname></term>
4045 <listitem><para>Takes a timespan. Specifies the lifetime of the Home Agent. An integer the default unit of seconds,
4046 in the range
1…
65535. Defaults to the value set to
<varname>RouterLifetimeSec=
</varname>.
</para>
4048 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
4053 <term><varname>HomeAgentPreference=
</varname></term>
4055 <listitem><para>Configures IPv6 Home Agent preference. Takes an integer in the range
0…
65535.
4056 Defaults to
0.
</para>
4058 <xi:include href=
"version-info.xml" xpointer=
"v255"/>
4066 <title>[IPv6Prefix] Section Options
</title>
4067 <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
4068 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink> for further
4071 <variablelist class='network-directives'
>
4074 <term><varname>AddressAutoconfiguration=
</varname></term>
4075 <term><varname>OnLink=
</varname></term>
4077 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
4078 autoconfigured with this prefix and whether the prefix can be used for
4079 onlink determination. Both settings default to
<literal>true
</literal>
4080 in order to ease configuration.
4083 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
4087 <term><varname>Prefix=
</varname></term>
4089 <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
4090 IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
4091 <literal>/
</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
4092 prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
4093 prefix to another.
</para>
4095 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
4099 <term><varname>PreferredLifetimeSec=
</varname></term>
4100 <term><varname>ValidLifetimeSec=
</varname></term>
4102 <listitem><para>Preferred and valid lifetimes for the prefix measured in seconds.
4103 <varname>PreferredLifetimeSec=
</varname> defaults to
1800 seconds (
30 minutes) and
4104 <varname>ValidLifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para>
4106 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
4110 <term><varname>Assign=
</varname></term>
4111 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
4114 <xi:include href=
"version-info.xml" xpointer=
"v246"/></listitem>
4118 <term><varname>Token=
</varname></term>
4120 <para>Specifies an optional address generation mode for assigning an address in each
4121 prefix. This accepts the same syntax as
<varname>Token=
</varname> in the [IPv6AcceptRA]
4122 section. If
<varname>Assign=
</varname> is set to false, then this setting will be ignored.
4123 Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
4125 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4130 <term><varname>RouteMetric=
</varname></term>
4132 <para>The metric of the prefix route. Takes an unsigned integer in the range
0…
4294967295.
4133 When unset or set to
0, the kernel's default value is used. This setting is ignored when
4134 <varname>Assign=
</varname> is false.
</para>
4136 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
4143 <title>[IPv6RoutePrefix] Section Options
</title>
4144 <para>One or more [IPv6RoutePrefix] sections contain the IPv6
4145 prefix routes that are announced via Router Advertisements. See
4146 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
4147 for further details.
</para>
4149 <variablelist class='network-directives'
>
4152 <term><varname>Route=
</varname></term>
4154 <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
4155 IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
4156 separated by a
<literal>/
</literal> character. Use multiple [IPv6RoutePrefix] sections to configure
4157 multiple IPv6 prefix routes.
</para>
4159 <xi:include href=
"version-info.xml" xpointer=
"v244"/></listitem>
4163 <term><varname>LifetimeSec=
</varname></term>
4165 <listitem><para>Lifetime for the route prefix measured in seconds.
4166 <varname>LifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para>
4168 <xi:include href=
"version-info.xml" xpointer=
"v244"/></listitem>
4175 <title>[IPv6PREF64Prefix] Section Options
</title>
4176 <para>One or more [IPv6PREF64Prefix] sections contain the IPv6 PREF64 (or NAT64) prefixes that are announced via Router
4177 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc8781">RFC
8781</ulink> for further
4180 <variablelist class='network-directives'
>
4183 <term><varname>Prefix=
</varname></term>
4185 <listitem><para>The IPv6 PREF64 (or NAT64) prefix that is to be distributed to hosts. The setting holds
4186 an IPv6 prefix that should be set up for NAT64 translation (PLAT) to allow
464XLAT on the network segment.
4187 Use multiple [IPv6PREF64Prefix] sections to configure multiple IPv6 prefixes since prefix lifetime may differ
4188 from one prefix to another. The prefix is an address with a prefix length, separated by a slash
4189 <literal>/
</literal> character. Valid NAT64 prefix length are
96,
64,
56,
48,
40, and
32 bits.
</para>
4191 <xi:include href=
"version-info.xml" xpointer=
"v255"/></listitem></varlistentry>
4194 <term><varname>LifetimeSec=
</varname></term>
4195 <listitem><para>Lifetime for the prefix measured in seconds. Should be greater than or equal to
<varname>RouterLifetimeSec=
</varname>.
4196 <varname>LifetimeSec=
</varname> defaults to
1800 seconds.
</para>
4198 <xi:include href=
"version-info.xml" xpointer=
"v255"/></listitem>
4204 <title>[Bridge] Section Options
</title>
4205 <para>The [Bridge] section accepts the following keys:
</para>
4207 <variablelist class='network-directives'
>
4209 <term><varname>UnicastFlood=
</varname></term>
4211 <para>Takes a boolean. Controls whether the bridge should flood
4212 traffic for which an FDB entry is missing and the destination
4213 is unknown through this port. When unset, the kernel's default will be used.
4216 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4220 <term><varname>MulticastFlood=
</varname></term>
4222 <para>Takes a boolean. Controls whether the bridge should flood
4223 traffic for which an MDB entry is missing and the destination
4224 is unknown through this port. When unset, the kernel's default will be used.
4227 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4231 <term><varname>MulticastToUnicast=
</varname></term>
4233 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
4234 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
4235 When unset, the kernel's default will be used.
4238 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
4242 <term><varname>NeighborSuppression=
</varname></term>
4244 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
4245 this port. When unset, the kernel's default will be used.
4248 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4252 <term><varname>Learning=
</varname></term>
4254 <para>Takes a boolean. Configures whether MAC address learning is enabled for
4255 this port. When unset, the kernel's default will be used.
4258 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4262 <term><varname>HairPin=
</varname></term>
4264 <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
4265 was received. When this flag is false, then the bridge will not forward traffic back out of the
4266 receiving port. When unset, the kernel's default will be used.
</para>
4268 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4272 <term><varname>Isolated=
</varname></term>
4274 <para>Takes a boolean. Configures whether this port is isolated or not. Within a bridge,
4275 isolated ports can only communicate with non-isolated ports. When set to true, this port can only
4276 communicate with other ports whose Isolated setting is false. When set to false, this port
4277 can communicate with any other ports. When unset, the kernel's default will be used.
</para>
4279 <xi:include href=
"version-info.xml" xpointer=
"v251"/>
4283 <term><varname>UseBPDU=
</varname></term>
4285 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
4286 processed by the bridge port. When unset, the kernel's default will be used.
</para>
4288 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4292 <term><varname>FastLeave=
</varname></term>
4294 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
4295 traffic on a port that receives an IGMP Leave message. It is only used with
4296 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
4298 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4302 <term><varname>AllowPortToBeRoot=
</varname></term>
4304 <para>Takes a boolean. Configures whether a given port is allowed to
4305 become a root port. Only used when STP is enabled on the bridge.
4306 When unset, the kernel's default will be used.
</para>
4308 <xi:include href=
"version-info.xml" xpointer=
"v223"/>
4312 <term><varname>ProxyARP=
</varname></term>
4314 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
4315 When unset, the kernel's default will be used.
</para>
4317 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4321 <term><varname>ProxyARPWiFi=
</varname></term>
4323 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
4324 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
4325 When unset, the kernel's default will be used.
</para>
4327 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4331 <term><varname>MulticastRouter=
</varname></term>
4333 <para>Configures this port for having multicast routers attached. A port with a multicast
4334 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
4335 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
4336 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
4337 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
4338 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
4340 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4344 <term><varname>Cost=
</varname></term>
4346 <para>Sets the
"cost" of sending packets of this interface.
4347 Each port in a bridge may have a different speed and the cost
4348 is used to decide which link to use. Faster interfaces
4349 should have lower costs. It is an integer value between
1 and
4352 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
4356 <term><varname>Priority=
</varname></term>
4358 <para>Sets the
"priority" of sending packets on this interface.
4359 Each port in a bridge may have a different priority which is used
4360 to decide which link to use. Lower value means higher priority.
4361 It is an integer value between
0 to
63. Networkd does not set any
4362 default, meaning the kernel default value of
32 is used.
</para>
4364 <xi:include href=
"version-info.xml" xpointer=
"v234"/>
4371 <title>[BridgeFDB] Section Options
</title>
4373 <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
4374 keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.
</para>
4376 <variablelist class='network-directives'
>
4378 <term><varname>MACAddress=
</varname></term>
4380 <para>As in the [Network] section. This key is mandatory.
</para>
4382 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
4386 <term><varname>Destination=
</varname></term>
4388 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
4390 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4394 <term><varname>VLANId=
</varname></term>
4396 <para>The VLAN ID for the new static MAC table entry. If
4397 omitted, no VLAN ID information is appended to the new static MAC
4400 <xi:include href=
"version-info.xml" xpointer=
"v219"/>
4404 <term><varname>VNI=
</varname></term>
4406 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
4407 the remote VXLAN tunnel endpoint. Takes a number in the range
1…
16777215.
4408 Defaults to unset.
</para>
4410 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4414 <term><varname>AssociatedWith=
</varname></term>
4416 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
4417 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
4418 <literal>use
</literal> means the address is in use. User space can use this option to
4419 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
4420 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
4421 means the address is associated with master devices fdb.
<literal>router
</literal> means
4422 the destination address is associated with a router. Note that it's valid if the referenced
4423 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
4425 <xi:include href=
"version-info.xml" xpointer=
"v243"/>
4429 <term><varname>OutgoingInterface=
</varname></term>
4431 <para>Specifies the name or index of the outgoing interface for the VXLAN device driver to
4432 reach the remote VXLAN tunnel endpoint. Defaults to unset.
</para>
4434 <xi:include href=
"version-info.xml" xpointer=
"v249"/>
4441 <title>[BridgeMDB] Section Options
</title>
4442 <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
4443 keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.
</para>
4445 <variablelist class='network-directives'
>
4447 <term><varname>MulticastGroupAddress=
</varname></term>
4449 <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.
</para>
4451 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4455 <term><varname>VLANId=
</varname></term>
4457 <para>The VLAN ID for the new entry. Valid ranges are
0 (no VLAN) to
4094. Optional, defaults to
0.
</para>
4459 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4466 <title>[LLDP] Section Options
</title>
4467 <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
4470 <variablelist class='network-directives'
>
4472 <term><varname>MUDURL=
</varname></term>
4474 <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
4475 LLDP packets. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
4476 [DHCPv4] section described above.
</para>
4478 <para>The MUD URLs received via LLDP packets are saved and can be read using the
4479 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
4481 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4488 <title>[CAN] Section Options
</title>
4489 <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
4490 following keys:
</para>
4491 <variablelist class='network-directives'
>
4493 <term><varname>BitRate=
</varname></term>
4495 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
4496 be used here. Takes a number in the range
1…
4294967295.
</para>
4498 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4502 <term><varname>SamplePoint=
</varname></term>
4504 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
4505 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>). This will be ignored when
4506 <varname>BitRate=
</varname> is unspecified.
</para>
4508 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4512 <term><varname>TimeQuantaNSec=
</varname></term>
4513 <term><varname>PropagationSegment=
</varname></term>
4514 <term><varname>PhaseBufferSegment1=
</varname></term>
4515 <term><varname>PhaseBufferSegment2=
</varname></term>
4516 <term><varname>SyncJumpWidth=
</varname></term>
4518 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
4519 synchronization jump width, which allow one to define the CAN bit-timing in a hardware
4520 independent format as proposed by the Bosch CAN
2.0 Specification.
4521 <varname>TimeQuantaNSec=
</varname> takes a timespan in nanoseconds.
4522 <varname>PropagationSegment=
</varname>,
<varname>PhaseBufferSegment1=
</varname>,
4523 <varname>PhaseBufferSegment2=
</varname>, and
<varname>SyncJumpWidth=
</varname> take number
4524 of time quantum specified in
<varname>TimeQuantaNSec=
</varname> and must be an unsigned
4525 integer in the range
0…
4294967295. These settings except for
4526 <varname>SyncJumpWidth=
</varname> will be ignored when
<varname>BitRate=
</varname> is
4529 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4533 <term><varname>DataBitRate=
</varname></term>
4534 <term><varname>DataSamplePoint=
</varname></term>
4536 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
4537 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
4539 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4543 <term><varname>DataTimeQuantaNSec=
</varname></term>
4544 <term><varname>DataPropagationSegment=
</varname></term>
4545 <term><varname>DataPhaseBufferSegment1=
</varname></term>
4546 <term><varname>DataPhaseBufferSegment2=
</varname></term>
4547 <term><varname>DataSyncJumpWidth=
</varname></term>
4549 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
4550 synchronization jump width for the data phase, if CAN-FD is used. These settings are
4551 analogous to the
<varname>TimeQuantaNSec=
</varname> or related settings.
</para>
4553 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4557 <term><varname>FDMode=
</varname></term>
4559 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
4560 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
4561 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys, or
4562 <varname>DataTimeQuanta=
</varname> and related settings.
</para>
4564 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4568 <term><varname>FDNonISO=
</varname></term>
4570 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
4571 interface. When unset, the kernel's default will be used.
</para>
4573 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4577 <term><varname>RestartSec=
</varname></term>
4579 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
4580 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
4581 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
4582 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
4583 automatic restart off. By default automatic restart is disabled.
</para>
4585 <xi:include href=
"version-info.xml" xpointer=
"v239"/>
4589 <term><varname>Termination=
</varname></term>
4591 <para>Takes a boolean or a termination resistor value in ohm in the range
0…
65535. When
4592 <literal>yes
</literal>, the termination resistor is set to
120 ohm. When
4593 <literal>no
</literal> or
<literal>0</literal> is set, the termination resistor is disabled.
4594 When unset, the kernel's default will be used.
</para>
4596 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4600 <term><varname>TripleSampling=
</varname></term>
4602 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
4603 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
4605 <xi:include href=
"version-info.xml" xpointer=
"v242"/>
4609 <term><varname>BusErrorReporting=
</varname></term>
4611 <para>Takes a boolean. When
<literal>yes
</literal>, reporting of CAN bus errors is activated
4612 (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
4613 unable to send recessive bit, bus overload, active error announcement, error occurred on
4614 transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
4615 single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.
</para>
4617 <xi:include href=
"version-info.xml" xpointer=
"v248"/>
4621 <term><varname>ListenOnly=
</varname></term>
4623 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
4624 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
4625 bit. Listen-only mode is important to debug CAN networks without interfering with the
4626 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
4629 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4633 <term><varname>Loopback=
</varname></term>
4635 <para>Takes a boolean. When
<literal>yes
</literal>, loopback mode is enabled. When the
4636 loopback mode is enabled, the interface treats messages transmitted by itself as received
4637 messages. The loopback mode is important to debug CAN networks. When unset, the kernel's
4638 default will be used.
</para>
4640 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4644 <term><varname>OneShot=
</varname></term>
4646 <para>Takes a boolean. When
<literal>yes
</literal>, one-shot mode is enabled. When unset,
4647 the kernel's default will be used.
</para>
4649 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4653 <term><varname>PresumeAck=
</varname></term>
4655 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will ignore missing CAN
4656 ACKs. When unset, the kernel's default will be used.
</para>
4658 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4662 <term><varname>ClassicDataLengthCode=
</varname></term>
4664 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will handle the
4bit data
4665 length code (DLC). When unset, the kernel's default will be used.
</para>
4667 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
4674 <title>[IPoIB] Section Options
</title>
4675 <para>The [IPoIB] section manages the IP over Infiniband and accepts the following keys:
</para>
4677 <variablelist class='network-directives'
>
4678 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_mode" />
4679 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_umcast" />
4684 <title>[QDisc] Section Options
</title>
4685 <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).
</para>
4687 <variablelist class='network-directives'
>
4689 <term><varname>Parent=
</varname></term>
4691 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
4692 or
<literal>ingress
</literal>. This is mandatory.
</para>
4694 <xi:include href=
"version-info.xml" xpointer=
"v244"/>
4698 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4703 <title>[NetworkEmulator] Section Options
</title>
4704 <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
4705 can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
4706 applications, or limit the bandwidth usage of a particular service to simulate internet connections.
4709 <variablelist class='network-directives'
>
4710 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4711 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4714 <term><varname>DelaySec=
</varname></term>
4716 <para>Specifies the fixed amount of delay to be added to all packets going out of the
4717 interface. Defaults to unset.
</para>
4719 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4724 <term><varname>DelayJitterSec=
</varname></term>
4726 <para>Specifies the chosen delay to be added to the packets outgoing to the network
4727 interface. Defaults to unset.
</para>
4729 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4734 <term><varname>PacketLimit=
</varname></term>
4736 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
4737 An unsigned integer in the range
0…
4294967294. Defaults to
1000.
</para>
4739 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4744 <term><varname>LossRate=
</varname></term>
4746 <para>Specifies an independent loss probability to be added to the packets outgoing from the
4747 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
4749 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4754 <term><varname>DuplicateRate=
</varname></term>
4756 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
4757 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
4759 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4766 <title>[TokenBucketFilter] Section Options
</title>
4767 <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
4770 <variablelist class='network-directives'
>
4771 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4772 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4775 <term><varname>LatencySec=
</varname></term>
4777 <para>Specifies the latency parameter, which specifies the maximum amount of time a
4778 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
4780 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4785 <term><varname>LimitBytes=
</varname></term>
4787 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
4788 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
4789 respectively, to the base of
1024. Defaults to unset.
</para>
4791 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4796 <term><varname>BurstBytes=
</varname></term>
4798 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
4799 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
4800 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to
4803 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4808 <term><varname>Rate=
</varname></term>
4810 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
4811 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
4812 Defaults to unset.
</para>
4814 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4819 <term><varname>MPUBytes=
</varname></term>
4821 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
4822 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
4823 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to zero.
</para>
4825 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4830 <term><varname>PeakRate=
</varname></term>
4832 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
4833 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
4834 1000. Defaults to unset.
</para>
4836 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4841 <term><varname>MTUBytes=
</varname></term>
4843 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
4844 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
4845 Defaults to unset.
</para>
4847 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4854 <title>[PIE] Section Options
</title>
4855 <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
4856 controller-Enhanced (PIE).
</para>
4858 <variablelist class='network-directives'
>
4859 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4860 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4863 <term><varname>PacketLimit=
</varname></term>
4865 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4866 incoming packets are dropped. An unsigned integer in the range
1…
4294967294. Defaults to unset and
4867 kernel's default is used.
</para>
4869 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4876 <title>[FlowQueuePIE] Section Options
</title>
4877 <para>The
<literal>[FlowQueuePIE]
</literal> section manages the queueing discipline
4878 (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).
</para>
4880 <variablelist class='network-directives'
>
4881 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4882 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4885 <term><varname>PacketLimit=
</varname></term>
4887 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4888 incoming packets are dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and
4889 kernel's default is used.
</para>
4891 <xi:include href=
"version-info.xml" xpointer=
"v247"/>
4898 <title>[StochasticFairBlue] Section Options
</title>
4899 <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
4902 <variablelist class='network-directives'
>
4903 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4904 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4907 <term><varname>PacketLimit=
</varname></term>
4909 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4910 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
4911 kernel's default is used.
</para>
4913 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4920 <title>[StochasticFairnessQueueing] Section Options
</title>
4921 <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
4922 fairness queueing (sfq).
</para>
4924 <variablelist class='network-directives'
>
4925 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4926 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4929 <term><varname>PerturbPeriodSec=
</varname></term>
4931 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
4933 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
4940 <title>[BFIFO] Section Options
</title>
4941 <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
4944 <variablelist class='network-directives'
>
4945 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4946 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4949 <term><varname>LimitBytes=
</varname></term>
4951 <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
4952 in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
4953 reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
4954 as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
4955 kernel default is used.
</para>
4957 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4964 <title>[PFIFO] Section Options
</title>
4965 <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
4968 <variablelist class='network-directives'
>
4969 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4970 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4973 <term><varname>PacketLimit=
</varname></term>
4975 <para>Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents
4976 overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this
4977 limit is reached, incoming packets are dropped. An unsigned integer in the range
4978 0…
4294967294. Defaults to unset and kernel's default is used.
</para>
4980 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
4987 <title>[PFIFOHeadDrop] Section Options
</title>
4988 <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
4989 Head Drop (pfifo_head_drop).
</para>
4991 <variablelist class='network-directives'
>
4992 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4993 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4996 <term><varname>PacketLimit=
</varname></term>
4998 <para>As in [PFIFO] section.
</para>
5000 <xi:include href=
"version-info.xml" xpointer=
"v246"/></listitem>
5006 <title>[PFIFOFast] Section Options
</title>
5007 <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
5008 (pfifo_fast).
</para>
5010 <variablelist class='network-directives'
>
5011 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5012 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5017 <title>[CAKE] Section Options
</title>
5018 <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
5021 <variablelist class='network-directives'
>
5022 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5023 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5026 <term><varname>Bandwidth=
</varname></term>
5028 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
5029 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
5030 unset and kernel's default is used.
</para>
5032 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5037 <term><varname>AutoRateIngress=
</varname></term>
5039 <para>Takes a boolean value. Enables automatic capacity estimation based on traffic arriving
5040 at this qdisc. This is most likely to be useful with cellular links, which tend to change
5041 quality randomly. If this setting is enabled, the
<varname>Bandwidth=
</varname> setting is
5042 used as an initial estimate. Defaults to unset, and the kernel's default is used.
</para>
5044 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5049 <term><varname>OverheadBytes=
</varname></term>
5051 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative.
5052 Takes an integer in the range -
64…
256. Defaults to unset and kernel's default is used.
5055 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5060 <term><varname>MPUBytes=
</varname></term>
5062 <para>Rounds each packet (including overhead) up to the specified bytes. Takes an integer in
5063 the range
1…
256. Defaults to unset and kernel's default is used.
</para>
5065 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5070 <term><varname>CompensationMode=
</varname></term>
5072 <para>Takes one of
<literal>none
</literal>,
<literal>atm
</literal>, or
<literal>ptm
</literal>.
5073 Specifies the compensation mode for overhead calculation. When
<literal>none
</literal>, no
5074 compensation is taken into account. When
<literal>atm
</literal>, enables the compensation for
5075 ATM cell framing, which is normally found on ADSL links. When
<literal>ptm
</literal>, enables
5076 the compensation for PTM encoding, which is normally found on VDSL2 links and uses a
64b/
65b
5077 encoding scheme. Defaults to unset and the kernel's default is used.
</para>
5079 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5084 <term><varname>UseRawPacketSize=
</varname></term>
5086 <para>Takes a boolean value. When true, the packet size reported by the Linux kernel will be
5087 used, instead of the underlying IP packet size. Defaults to unset, and the kernel's default
5090 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5095 <term><varname>FlowIsolationMode=
</varname></term>
5097 <para>CAKE places packets from different flows into different queues, then packets from each
5098 queue are delivered fairly. This specifies whether the fairness is based on source address,
5099 destination address, individual flows, or any combination of those. The available values are:
5104 <term><option>none
</option></term>
5106 The flow isolation is disabled, and all traffic passes through a single queue.
5109 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5112 <term><option>src-host
</option></term>
5114 Flows are defined only by source address. Equivalent to the
<literal>srchost
</literal>
5115 option for
<command>tc qdisc
</command> command. See also
5116 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5119 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5122 <term><option>dst-host
</option></term>
5124 Flows are defined only by destination address. Equivalent to the
5125 <literal>dsthost
</literal> option for
<command>tc qdisc
</command> command. See also
5126 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5129 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5132 <term><option>hosts
</option></term>
5134 Flows are defined by source-destination host pairs. Equivalent to the same option for
5135 <command>tc qdisc
</command> command. See also
5136 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5139 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5142 <term><option>flows
</option></term>
5144 Flows are defined by the entire
5-tuple of source address, destination address,
5145 transport protocol, source port and destination port. Equivalent to the same option for
5146 <command>tc qdisc
</command> command. See also
5147 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5150 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5153 <term><option>dual-src-host
</option></term>
5155 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
5156 fairness is applied first over source addresses, then over individual flows. Equivalent
5157 to the
<literal>dual-srchost
</literal> option for
<command>tc qdisc
</command> command.
5159 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5162 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5165 <term><option>dual-dst-host
</option></term>
5167 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
5168 fairness is applied first over destination addresses, then over individual flows.
5169 Equivalent to the
<literal>dual-dsthost
</literal> option for
5170 <command>tc qdisc
</command> command. See also
5171 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5174 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5177 <term><option>triple
</option></term>
5179 Flows are defined by the
5-tuple (see
<literal>flows
</literal>), and fairness is
5180 applied over source and destination addresses, and also over individual flows.
5181 Equivalent to the
<literal>triple-isolate
</literal> option for
5182 <command>tc qdisc
</command> command. See also
5183 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
5186 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5190 <para>Defaults to unset and the kernel's default is used.
</para>
5192 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5197 <term><varname>NAT=
</varname></term>
5199 <para>Takes a boolean value. When true, CAKE performs a NAT lookup before applying
5200 flow-isolation rules, to determine the true addresses and port numbers of the packet, to
5201 improve fairness between hosts inside the NAT. This has no practical effect when
5202 <varname>FlowIsolationMode=
</varname> is
<literal>none
</literal> or
<literal>flows
</literal>,
5203 or if NAT is performed on a different host. Defaults to unset, and the kernel's default is
5206 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5211 <term><varname>PriorityQueueingPreset=
</varname></term>
5213 <para>CAKE divides traffic into
<literal>tins
</literal>, and each tin has its own independent
5214 set of flow-isolation queues, bandwidth threshold, and priority. This specifies the preset of
5215 tin profiles. The available values are:
</para>
5219 <term><option>besteffort
</option></term>
5221 Disables priority queueing by placing all traffic in one tin.
5224 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5227 <term><option>precedence
</option></term>
5229 Enables priority queueing based on the legacy interpretation of TOS
5230 <literal>Precedence
</literal> field. Use of this preset on the modern Internet is
5234 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5237 <term><option>diffserv8
</option></term>
5239 Enables priority queueing based on the Differentiated Service
5240 (
<literal>DiffServ
</literal>) field with eight tins: Background Traffic, High
5241 Throughput, Best Effort, Video Streaming, Low Latency Transactions, Interactive Shell,
5242 Minimum Latency, and Network Control.
5245 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5248 <term><option>diffserv4
</option></term>
5250 Enables priority queueing based on the Differentiated Service
5251 (
<literal>DiffServ
</literal>) field with four tins: Background Traffic, Best Effort,
5252 Streaming Media, and Latency Sensitive.
5255 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5258 <term><option>diffserv3
</option></term>
5260 Enables priority queueing based on the Differentiated Service
5261 (
<literal>DiffServ
</literal>) field with three tins: Background Traffic, Best Effort,
5262 and Latency Sensitive.
5265 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
5269 <para>Defaults to unset, and the kernel's default is used.
</para>
5271 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5276 <term><varname>FirewallMark=
</varname></term>
5278 <para>Takes an integer in the range
1…
4294967295. When specified, firewall-mark-based
5279 overriding of CAKE's tin selection is enabled. Defaults to unset, and the kernel's default is
5282 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5287 <term><varname>Wash=
</varname></term>
5289 <para>Takes a boolean value. When true, CAKE clears the DSCP fields, except for ECN bits, of
5290 any packet passing through CAKE. Defaults to unset, and the kernel's default is used.
</para>
5292 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5297 <term><varname>SplitGSO=
</varname></term>
5299 <para>Takes a boolean value. When true, CAKE will split General Segmentation Offload (GSO)
5300 super-packets into their on-the-wire components and dequeue them individually. Defaults to
5301 unset, and the kernel's default is used.
</para>
5303 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
5308 <term><varname>RTTSec=
</varname></term>
5310 <para>Specifies the RTT for the filter. Takes a timespan. Typical values are e.g.
100us for
5311 extremely high-performance
10GigE+ networks like datacentre,
1ms for non-WiFi LAN connections,
5312 100ms for typical internet connections. Defaults to unset, and the kernel's default will be used.
5315 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
5320 <term><varname>AckFilter=
</varname></term>
5322 <para>Takes a boolean value, or special value
<literal>aggressive
</literal>. If enabled, ACKs in
5323 each flow are queued and redundant ACKs to the upstream are dropped. If yes, the filter will always
5324 keep at least two redundant ACKs in the queue, while in
<literal>aggressive
</literal> mode, it will
5325 filter down to a single ACK. This may improve download throughput on links with very asymmetrical
5326 rate limits. Defaults to unset, and the kernel's default will be used.
</para>
5328 <xi:include href=
"version-info.xml" xpointer=
"v253"/>
5336 <title>[ControlledDelay] Section Options
</title>
5337 <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
5338 controlled delay (CoDel).
</para>
5340 <variablelist class='network-directives'
>
5341 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5342 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5345 <term><varname>PacketLimit=
</varname></term>
5347 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
5348 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
5349 kernel's default is used.
</para>
5351 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5356 <term><varname>TargetSec=
</varname></term>
5358 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
5359 Defaults to unset and kernel's default is used.
</para>
5361 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5366 <term><varname>IntervalSec=
</varname></term>
5368 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
5369 become too stale. Defaults to unset and kernel's default is used.
</para>
5371 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5376 <term><varname>ECN=
</varname></term>
5378 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
5379 unset and kernel's default is used.
</para>
5381 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5386 <term><varname>CEThresholdSec=
</varname></term>
5388 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5389 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5391 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5398 <title>[DeficitRoundRobinScheduler] Section Options
</title>
5399 <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
5400 Robin Scheduler (DRR).
</para>
5402 <variablelist class='network-directives'
>
5403 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5404 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5409 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
5410 <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
5411 Robin Scheduler (DRR).
</para>
5413 <variablelist class='network-directives'
>
5414 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5415 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5418 <term><varname>QuantumBytes=
</varname></term>
5420 <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
5421 to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5422 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to the MTU of the
5425 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5433 <title>[EnhancedTransmissionSelection] Section Options
</title>
5434 <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
5435 Transmission Selection (ETS).
</para>
5437 <variablelist class='network-directives'
>
5438 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5439 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5442 <term><varname>Bands=
</varname></term>
5444 <para>Specifies the number of bands. An unsigned integer in the range
1…
16. This value has to be at
5445 least large enough to cover the strict bands specified through the
<varname>StrictBands=
</varname>
5446 and bandwidth-sharing bands specified in
<varname>QuantumBytes=
</varname>.
</para>
5448 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5453 <term><varname>StrictBands=
</varname></term>
5455 <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
5456 the range
1…
16.
</para>
5458 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5463 <term><varname>QuantumBytes=
</varname></term>
5465 <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
5466 suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5467 respectively, to the base of
1024. This setting can be specified multiple times. If an empty
5468 string is assigned, then the all previous assignments are cleared.
</para>
5470 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5475 <term><varname>PriorityMap=
</varname></term>
5477 <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
5478 separated list of numbers. The first number indicates which band the packets with priority
0 should
5479 be put to, the second is for priority
1, and so on. There can be up to
16 numbers in the list. If
5480 there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
5481 the last one. Each band number must be in the range
0…
255. This setting can be specified multiple
5482 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
5484 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5491 <title>[GenericRandomEarlyDetection] Section Options
</title>
5492 <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
5493 Early Detection (GRED).
</para>
5495 <variablelist class='network-directives'
>
5496 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5497 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5500 <term><varname>VirtualQueues=
</varname></term>
5502 <para>Specifies the number of virtual queues. Takes an integer in the range
1…
16. Defaults to unset
5503 and kernel's default is used.
</para>
5505 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5510 <term><varname>DefaultVirtualQueue=
</varname></term>
5512 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
5513 Defaults to unset and kernel's default is used.
</para>
5515 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5520 <term><varname>GenericRIO=
</varname></term>
5522 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
5523 unset and kernel's default is used.
</para>
5525 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5532 <title>[FairQueueingControlledDelay] Section Options
</title>
5533 <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
5534 controlled delay (FQ-CoDel).
</para>
5536 <variablelist class='network-directives'
>
5537 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5538 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5541 <term><varname>PacketLimit=
</varname></term>
5543 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
5544 dropped. Defaults to unset and kernel's default is used.
</para>
5546 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5551 <term><varname>MemoryLimitBytes=
</varname></term>
5553 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
5554 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5555 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
5557 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5562 <term><varname>Flows=
</varname></term>
5564 <para>Specifies the number of flows into which the incoming packets are classified.
5565 Defaults to unset and kernel's default is used.
</para>
5567 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5572 <term><varname>TargetSec=
</varname></term>
5574 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
5575 Defaults to unset and kernel's default is used.
</para>
5577 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5582 <term><varname>IntervalSec=
</varname></term>
5584 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
5585 become too stale. Defaults to unset and kernel's default is used.
</para>
5587 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5592 <term><varname>QuantumBytes=
</varname></term>
5594 <para>Specifies the number of bytes used as the
"deficit" in the fair queuing algorithm timespan.
5595 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5596 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
5598 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5603 <term><varname>ECN=
</varname></term>
5605 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
5606 unset and kernel's default is used.
</para>
5608 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5613 <term><varname>CEThresholdSec=
</varname></term>
5615 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5616 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5618 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5625 <title>[FairQueueing] Section Options
</title>
5626 <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
5629 <variablelist class='network-directives'
>
5630 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5631 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5634 <term><varname>PacketLimit=
</varname></term>
5636 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
5637 dropped. Defaults to unset and kernel's default is used.
</para>
5639 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5644 <term><varname>FlowLimit=
</varname></term>
5646 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
5647 unset and kernel's default is used.
</para>
5649 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5654 <term><varname>QuantumBytes=
</varname></term>
5656 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
5657 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5658 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
5659 default is used.
</para>
5661 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5666 <term><varname>InitialQuantumBytes=
</varname></term>
5668 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
5669 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
5670 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
5671 kernel's default is used.
</para>
5673 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5678 <term><varname>MaximumRate=
</varname></term>
5680 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
5681 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
5682 1000. Defaults to unset and kernel's default is used.
</para>
5684 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5689 <term><varname>Buckets=
</varname></term>
5691 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
5692 kernel's default is used.
</para>
5694 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5699 <term><varname>OrphanMask=
</varname></term>
5701 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
5702 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
5703 kernel's default is used.
</para>
5705 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5710 <term><varname>Pacing=
</varname></term>
5712 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
5713 default is used.
</para>
5715 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5720 <term><varname>CEThresholdSec=
</varname></term>
5722 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
5723 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
5725 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5732 <title>[TrivialLinkEqualizer] Section Options
</title>
5733 <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
5734 equalizer (teql).
</para>
5736 <variablelist class='network-directives'
>
5737 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5738 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5741 <term><varname>Id=
</varname></term>
5743 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
5744 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
5745 <constant>max_equalizers=N+
1</constant> option must be loaded before
5746 <command>systemd-networkd
</command> is started.
</para>
5748 <xi:include href=
"version-info.xml" xpointer=
"v245"/>
5755 <title>[HierarchyTokenBucket] Section Options
</title>
5756 <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
5757 bucket (htb).
</para>
5759 <variablelist class='network-directives'
>
5760 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5761 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5764 <term><varname>DefaultClass=
</varname></term>
5766 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
5767 to the class. Defaults to unset.
</para>
5769 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5774 <term><varname>RateToQuantum=
</varname></term>
5776 <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
5777 configured in
<varname>Rate=
</varname> by
<varname>RateToQuantum=
</varname>.
</para>
5779 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5786 <title>[HierarchyTokenBucketClass] Section Options
</title>
5787 <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
5790 <variablelist class='network-directives'
>
5791 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5792 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5795 <term><varname>Priority=
</varname></term>
5797 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
5798 priority field are tried for packets first.
</para>
5800 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5805 <term><varname>QuantumBytes=
</varname></term>
5807 <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
5808 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
5811 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5816 <term><varname>MTUBytes=
</varname></term>
5818 <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
5819 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
5821 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5826 <term><varname>OverheadBytes=
</varname></term>
5828 <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
5829 computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
5830 Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
5832 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5837 <term><varname>Rate=
</varname></term>
5839 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
5840 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
5841 to the base of
1000. This setting is mandatory.
</para>
5843 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5848 <term><varname>CeilRate=
</varname></term>
5850 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
5851 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
5852 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
5855 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5860 <term><varname>BufferBytes=
</varname></term>
5862 <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
5863 with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
5864 to the base of
1024.
</para>
5866 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5871 <term><varname>CeilBufferBytes=
</varname></term>
5873 <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
5874 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
5875 respectively, to the base of
1024.
</para>
5877 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5884 <title>[HeavyHitterFilter] Section Options
</title>
5885 <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
5888 <variablelist class='network-directives'
>
5889 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5890 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5893 <term><varname>PacketLimit=
</varname></term>
5895 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
5896 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
5897 kernel's default is used.
</para>
5899 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5906 <title>[QuickFairQueueing] Section Options
</title>
5907 <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
5910 <variablelist class='network-directives'
>
5911 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
5912 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
5917 <title>[QuickFairQueueingClass] Section Options
</title>
5918 <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
5921 <variablelist class='network-directives'
>
5922 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
5923 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
5926 <term><varname>Weight=
</varname></term>
5928 <para>Specifies the weight of the class. Takes an integer in the range
1…
1023. Defaults to
5929 unset in which case the kernel default is used.
</para>
5931 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5936 <term><varname>MaxPacketBytes=
</varname></term>
5938 <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the
5939 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
5940 1024. When unset, the kernel default is used.
</para>
5942 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
5949 <title>[BridgeVLAN] Section Options
</title>
5951 The [BridgeVLAN] section manages the VLAN ID configurations of a bridge master or port, and accepts the
5952 following keys. To make the settings in this section take an effect,
5953 <varname>VLANFiltering=
</varname> option has to be enabled on the bridge master, see the [Bridge]
5955 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
5956 If at least one valid settings specified in this section in a .network file for an interface, all
5957 assigned VLAN IDs on the interface that are not configured in the .network file will be removed. If
5958 VLAN IDs on an interface need to be managed by other tools, then the settings in this section cannot
5959 be used in the matching .network file.
5962 <variablelist class='network-directives'
>
5964 <term><varname>VLAN=
</varname></term>
5966 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. Takes an
5967 integer in the range
1…
4094. This setting can be specified multiple times. If an empty string is
5968 assigned, then the all previous assignments are cleared.
</para>
5970 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5974 <term><varname>EgressUntagged=
</varname></term>
5976 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
5977 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will
5978 enable the VLAN ID for ingress as well. This can be either a single ID or a range M-N. This
5979 setting can be specified multiple times. If an empty string is assigned, then the all previous
5980 assignments are cleared.
</para>
5982 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
5986 <term><varname>PVID=
</varname></term>
5988 <para>The port VLAN ID specified here is assigned to all untagged frames at ingress. Takes an
5989 VLAN ID or negative boolean value (e.g.
<literal>no
</literal>). When false, the currently
5990 assigned port VLAN ID will be dropped. Configuring
<varname>PVID=
</varname> implicates the use of
5991 <varname>VLAN=
</varname> setting in the above and will enable the VLAN ID for ingress as well.
5992 Defaults to unset, and will keep the assigned port VLAN ID if exists.
</para>
5994 <xi:include href=
"version-info.xml" xpointer=
"v231"/>
6001 <title>Examples
</title>
6003 <title>Static network configuration
</title>
6005 <programlisting># /etc/systemd/network/
50-static.network
6010 Address=
192.168.0.15/
24
6011 Gateway=
192.168.0.1</programlisting>
6013 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
6014 specified gateway will be used for a default route.
</para>
6018 <title>DHCP on ethernet links
</title>
6020 <programlisting># /etc/systemd/network/
80-dhcp.network
6025 DHCP=yes
</programlisting>
6027 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
6028 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
6032 <title>IPv6 Prefix Delegation (DHCPv6 PD)
</title>
6034 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-upstream.network
6041 # The below setting is optional, to also assign an address in the delegated prefix
6042 # to the upstream interface. If not necessary, then comment out the line below and
6043 # the [DHCPPrefixDelegation] section.
6044 DHCPPrefixDelegation=yes
6046 # If the upstream network provides Router Advertisement with Managed bit set,
6047 # then comment out the line below and WithoutRA= setting in the [DHCPv6] section.
6053 [DHCPPrefixDelegation]
6054 UplinkInterface=:self
6056 Announce=no
</programlisting>
6058 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-downstream.network
6063 DHCPPrefixDelegation=yes
6066 # It is expected that the host is acting as a router. So, usually it is not
6067 # necessary to receive Router Advertisement from other hosts in the downstream network.
6070 [DHCPPrefixDelegation]
6071 UplinkInterface=enp1s0
6073 Announce=yes
</programlisting>
6075 <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
6076 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
6077 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
6082 <title>IPv6 Prefix Delegation (DHCPv4
6RD)
</title>
6084 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-upstream.network
6091 # When DHCPv4-
6RD is used, the upstream network does not support IPv6.
6092 # Hence, it is not necessary to wait for Router Advertisement, which is enabled by default.
6096 Use6RD=yes
</programlisting>
6098 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-downstream.network
6103 DHCPPrefixDelegation=yes
6106 # It is expected that the host is acting as a router. So, usually it is not
6107 # necessary to receive Router Advertisement from other hosts in the downstream network.
6110 [DHCPPrefixDelegation]
6111 UplinkInterface=enp1s0
6113 Announce=yes
</programlisting>
6115 <para>This will enable DHCPv4-
6RD on the interface enp1s0 as an upstream interface where the
6116 DHCPv4 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
6117 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
6122 <title>A bridge with two enslaved links
</title>
6124 <programlisting># /etc/systemd/network/
25-bridge-static.netdev
6127 Kind=bridge
</programlisting>
6129 <programlisting># /etc/systemd/network/
25-bridge-static.network
6134 Address=
192.168.0.15/
24
6136 DNS=
192.168.0.1</programlisting>
6138 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
6143 Bridge=bridge0
</programlisting>
6145 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
6150 Bridge=bridge0
</programlisting>
6152 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
6153 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
6154 and network assigned, and a default route via the specified gateway will be
6155 added. The specified DNS server will be added to the global list of DNS resolvers.
6160 <title>Bridge port with VLAN forwarding
</title>
6163 # /etc/systemd/network/
25-bridge-slave-interface-
1.network
6179 EgressUntagged=
300-
400</programlisting>
6181 <para>This overrides the configuration specified in the previous example for the
6182 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
6183 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
6184 untagged when they leave on this interface. Untagged packets which arrive on this
6185 interface will be assigned VLAN ID
42.
</para>
6189 <title>Various tunnels
</title>
6191 <programlisting>/etc/systemd/network/
25-tunnels.network
6202 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
6208 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
6214 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
6220 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
6226 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
6227 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
6231 <title>A bond device
</title>
6233 <programlisting># /etc/systemd/network/
30-bond1.network
6241 <programlisting># /etc/systemd/network/
30-bond1.netdev
6247 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
6249 MACAddress=
52:
54:
00:e9:
64:
41
6255 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
6257 MACAddress=
52:
54:
00:e9:
64:
42
6263 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
6264 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
6265 will be used to acquire an address.
</para>
6269 <title>Virtual Routing and Forwarding (VRF)
</title>
6270 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
6271 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
6272 within the routing table defined during VRF creation. For kernels before
4.8 traffic
6273 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
6275 <programlisting># /etc/systemd/network/
25-vrf.network
6285 <title>MacVTap
</title>
6286 <para>This brings up a network interface
<literal>macvtap-test
</literal>
6287 and attaches it to
<literal>enp0s25
</literal>.
</para>
6288 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
6293 MACVTAP=macvtap-test
6298 <title>A Xfrm interface with physical underlying device.
</title>
6300 <programlisting># /etc/systemd/network/
27-xfrm.netdev
6306 InterfaceId=
7</programlisting>
6308 <programlisting># /etc/systemd/network/
27-eth0.network
6313 Xfrm=xfrm0
</programlisting>
6315 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
6316 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
6317 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
6323 <title>See Also
</title>
6324 <para><simplelist type=
"inline">
6325 <member><citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
6326 <member><citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
6327 <member><citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
6328 <member><citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
6329 <member><citerefentry><refentrytitle>systemd-network-generator.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
6330 <member><citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
6331 </simplelist></para>