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1 <?xml version='1.0'?>
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
5
6 <refentry id="systemd.network" conditional='ENABLE_NETWORKD'
7 xmlns:xi="http://www.w3.org/2001/XInclude">
8
9 <refentryinfo>
10 <title>systemd.network</title>
11 <productname>systemd</productname>
12 </refentryinfo>
13
14 <refmeta>
15 <refentrytitle>systemd.network</refentrytitle>
16 <manvolnum>5</manvolnum>
17 </refmeta>
18
19 <refnamediv>
20 <refname>systemd.network</refname>
21 <refpurpose>Network configuration</refpurpose>
22 </refnamediv>
23
24 <refsynopsisdiv>
25 <para><filename><replaceable>network</replaceable>.network</filename></para>
26 </refsynopsisdiv>
27
28 <refsect1>
29 <title>Description</title>
30
31 <para>A plain ini-style text file that encodes network configuration for matching network interfaces,
32 used by
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>
36
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>
39
40 <para>The <filename>.network</filename> files are read from the files located in the system network
41 directories <filename>/usr/lib/systemd/network</filename> and
42 <filename>/usr/local/lib/systemd/network</filename>, the volatile runtime network directory
43 <filename>/run/systemd/network</filename> and the local administration network directory
44 <filename>/etc/systemd/network</filename>. All configuration files are collectively sorted and processed
45 in lexical order, regardless of the directories in which they live. However, files with identical
46 filenames replace each other. Files in <filename>/etc/</filename> have the highest priority, files in
47 <filename>/run/</filename> take precedence over files with the same name under
48 <filename>/usr/</filename>. This can be used to override a system-supplied configuration file with a local
49 file if needed. As a special case, an empty file (file size 0) or symlink with the same name pointing to
50 <filename>/dev/null</filename> disables the configuration file entirely (it is "masked").</para>
51
52 <para>Along with the network file <filename>foo.network</filename>, a "drop-in" directory
53 <filename>foo.network.d/</filename> may exist. All files with the suffix
54 <literal>.conf</literal> from this directory will be parsed after the file itself is
55 parsed. This is useful to alter or add configuration settings, without having to modify the main
56 configuration file. Each drop-in file must have appropriate section headers.</para>
57
58 <para>In addition to <filename>/etc/systemd/network</filename>, drop-in <literal>.d</literal>
59 directories can be placed in <filename>/usr/lib/systemd/network</filename> or
60 <filename>/run/systemd/network</filename> directories. Drop-in files in
61 <filename>/etc/</filename> take precedence over those in <filename>/run/</filename> which in turn
62 take precedence over those in <filename>/usr/lib/</filename>. Drop-in files under any of these
63 directories take precedence over the main network file wherever located.</para>
64 </refsect1>
65
66 <refsect1>
67 <title>[Match] Section Options</title>
68
69 <para>The network file contains a [Match] section, which determines if a given network file may be
70 applied to a given device; and a [Network] section specifying how the device should be configured. The
71 first (in lexical order) of the network files that matches a given device is applied, all later files
72 are ignored, even if they match as well.</para>
73
74 <para>A network file is said to match a network interface if all matches specified by the [Match]
75 section are satisfied. When a network file does not contain valid settings in [Match] section, then the
76 file will match all interfaces and <command>systemd-networkd</command> warns about that. Hint: to avoid
77 the warning and to make it clear that all interfaces shall be matched, add the following:
78 <programlisting>Name=*</programlisting> The following keys are accepted:</para>
79
80 <variablelist class='network-directives'>
81 <xi:include href="systemd.link.xml" xpointer="mac-address" />
82 <xi:include href="systemd.link.xml" xpointer="permanent-mac-address" />
83 <xi:include href="systemd.link.xml" xpointer="path" />
84 <xi:include href="systemd.link.xml" xpointer="driver" />
85 <xi:include href="systemd.link.xml" xpointer="type" />
86 <xi:include href="systemd.link.xml" xpointer="property" />
87
88 <varlistentry>
89 <term><varname>Name=</varname></term>
90 <listitem>
91 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
92 by the udev property <literal>INTERFACE</literal>, or device's alternative names. If the
93 list is prefixed with a "!", the test is inverted.</para>
94 </listitem>
95 </varlistentry>
96
97 <varlistentry>
98 <term><varname>WLANInterfaceType=</varname></term>
99 <listitem>
100 <para>A whitespace-separated list of wireless network type. Supported values are
101 <literal>ad-hoc</literal>, <literal>station</literal>, <literal>ap</literal>,
102 <literal>ap-vlan</literal>, <literal>wds</literal>, <literal>monitor</literal>,
103 <literal>mesh-point</literal>, <literal>p2p-client</literal>, <literal>p2p-go</literal>,
104 <literal>p2p-device</literal>, <literal>ocb</literal>, and <literal>nan</literal>. If the
105 list is prefixed with a "!", the test is inverted.
106 </para>
107 </listitem>
108 </varlistentry>
109
110 <varlistentry>
111 <term><varname>SSID=</varname></term>
112 <listitem>
113 <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
114 connected wireless LAN. If the list is prefixed with a "!", the test is inverted.
115 </para>
116 </listitem>
117 </varlistentry>
118
119 <varlistentry>
120 <term><varname>BSSID=</varname></term>
121 <listitem>
122 <para>A whitespace-separated list of hardware address of the currently connected wireless
123 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
124 <varname>MACAddress=</varname>. This option may appear more than once, in which case the
125 lists are merged. If the empty string is assigned to this option, the list is reset.</para>
126 </listitem>
127 </varlistentry>
128
129 <xi:include href="systemd.link.xml" xpointer="host" />
130 <xi:include href="systemd.link.xml" xpointer="virtualization" />
131 <xi:include href="systemd.link.xml" xpointer="kernel-command-line" />
132 <xi:include href="systemd.link.xml" xpointer="kernel-version" />
133 <xi:include href="systemd.link.xml" xpointer="architecture" />
134 </variablelist>
135
136 </refsect1>
137
138 <refsect1>
139 <title>[Link] Section Options</title>
140
141 <para> The [Link] section accepts the following keys:</para>
142
143 <variablelist class='network-directives'>
144 <varlistentry>
145 <term><varname>MACAddress=</varname></term>
146 <listitem>
147 <para>The hardware address to set for the device.</para>
148 </listitem>
149 </varlistentry>
150 <varlistentry>
151 <term><varname>MTUBytes=</varname></term>
152 <listitem>
153 <para>The maximum transmission unit in bytes to set for the
154 device. The usual suffixes K, M, G, are supported and are
155 understood to the base of 1024.</para>
156 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
157 below 1280 (the minimum MTU for IPv6) it will automatically be increased to this value.</para>
158 </listitem>
159 </varlistentry>
160 <varlistentry>
161 <term><varname>ARP=</varname></term>
162 <listitem>
163 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
164 for this interface is enabled. When unset, the kernel's default will be used.</para>
165 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
166 interfaces atop a single lower-level physical interface, which will then only serve as a
167 link/"bridge" device aggregating traffic to the same physical link and not participate in
168 the network otherwise. Defaults to unset.</para>
169 </listitem>
170 </varlistentry>
171 <varlistentry>
172 <term><varname>Multicast=</varname></term>
173 <listitem>
174 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults to unset.</para>
175 </listitem>
176 </varlistentry>
177 <varlistentry>
178 <term><varname>AllMulticast=</varname></term>
179 <listitem>
180 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the network.
181 This happens when multicast routing is enabled. Defaults to unset.</para>
182 </listitem>
183 </varlistentry>
184 <varlistentry>
185 <term><varname>Promiscuous=</varname></term>
186 <listitem>
187 <para>Takes a boolean. If set to true, promiscuous mode of the interface is enabled.
188 Defaults to unset.</para>
189 </listitem>
190 </varlistentry>
191 <varlistentry>
192 <term><varname>Unmanaged=</varname></term>
193 <listitem>
194 <para>Takes a boolean. When <literal>yes</literal>, no attempts are
195 made to bring up or configure matching links, equivalent to
196 when there are no matching network files. Defaults to
197 <literal>no</literal>.</para>
198 <para>This is useful for preventing later matching network
199 files from interfering with certain interfaces that are fully
200 controlled by other applications.</para>
201 </listitem>
202 </varlistentry>
203 <varlistentry>
204 <term><varname>Group=</varname></term>
205 <listitem>
206 <para>Link groups are similar to port ranges found in managed switches.
207 When network interfaces are added to a numbered group, operations on
208 all the interfaces from that group can be performed at once. An unsigned
209 integer in the range 0…4294967294. Defaults to unset.</para>
210 </listitem>
211 </varlistentry>
212 <varlistentry>
213 <term><varname>RequiredForOnline=</varname></term>
214 <listitem>
215 <para>Takes a boolean or a minimum operational state and an optional maximum operational state.
216 Please see <citerefentry><refentrytitle>networkctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
217 for possible operational states. When <literal>yes</literal>, the network is deemed required when
218 determining whether the system is online when running
219 <command>systemd-networkd-wait-online</command>. When <literal>no</literal>, the network is ignored
220 when checking for online state. When a minimum operational state and an optional maximum operational
221 state are set, <literal>yes</literal> is implied, and this controls the minimum and maximum
222 operational state required for the network interface to be considered online.
223 Defaults to <literal>yes</literal>.</para>
224
225 <para>The network will be brought up normally in all cases, but in
226 the event that there is no address being assigned by DHCP or the
227 cable is not plugged in, the link will simply remain offline and be
228 skipped automatically by <command>systemd-networkd-wait-online</command>
229 if <literal>RequiredForOnline=no</literal>.</para>
230 </listitem>
231 </varlistentry>
232 <varlistentry>
233 <term><varname>RequiredFamilyForOnline=</varname></term>
234 <listitem>
235 <para>Specifies an address family. When specified,
236 <command>systemd-networkd-wait-online</command> waits for at least one routable or link-local
237 IP address in the family should be configured on the link. Takes one of
238 <literal>ipv4</literal>, <literal>ipv6</literal>, <literal>both</literal>, or
239 <literal>any</literal>. Defaults to <literal>any</literal>. Note that this will be used only
240 when <varname>RequiredForOnline=</varname> is true, or its minimum operational state is
241 <literal>degraded</literal> or above. Otherwise, it will be ignored.</para>
242 </listitem>
243 </varlistentry>
244 <varlistentry>
245 <term><varname>ActivationPolicy=</varname></term>
246 <listitem>
247 <para>Specifies the policy for <command>systemd-networkd</command> managing the link
248 administrative state. Specifically, this controls how <command>systemd-networkd</command>
249 changes the network device's <literal>IFF_UP</literal> flag, which is sometimes
250 controlled by system administrators by running e.g., <command>ip set dev eth0 up</command>
251 or <command>ip set dev eth0 down</command>, and can also be changed with
252 <command>networkctl up eth0</command> or <command>networkctl down eth0</command>.</para>
253
254 <para>Takes one of <literal>up</literal>, <literal>always-up</literal>,
255 <literal>manual</literal>, <literal>always-down</literal>, <literal>down</literal>,
256 or <literal>bound</literal>. When <literal>manual</literal>, <command>systemd-networkd</command>
257 will not change the link's admin state automatically; the system administrator must bring the
258 interface up or down manually, as desired. When <literal>up</literal> (the default) or
259 <literal>always-up</literal>, or <literal>down</literal> or <literal>always-down</literal>,
260 <command>systemd-networkd</command> will set the link up or down, respectively,
261 when the interface is (re)configured. When <literal>always-up</literal> or
262 <literal>always-down</literal>, <command>systemd-networkd</command> will set the link up
263 or down, respectively, any time <command>systemd-networkd</command> detects a change in
264 the administrative state. When <varname>BindCarrier=</varname> is also set, this is
265 automatically set to <literal>bound</literal> and any other value is ignored.</para>
266
267 <para>The administrative state is not the same as the carrier state, so using
268 <literal>always-up</literal> does not mean the link will never lose carrier. The link
269 carrier depends on both the administrative state as well as the network device's physical
270 connection. However, to avoid reconfiguration failures, when using <literal>always-up</literal>,
271 <varname>IgnoreCarrierLoss=</varname> is forced to true.</para>
272 </listitem>
273 </varlistentry>
274 </variablelist>
275 </refsect1>
276
277 <refsect1>
278 <title>[SR-IOV] Section Options</title>
279 <para>The [SR-IOV] section accepts the following keys. Specify several [SR-IOV] sections to configure
280 several SR-IOVs. SR-IOV provides the ability to partition a single physical PCI resource into virtual
281 PCI functions which can then be injected into a VM. In the case of network VFs, SR-IOV improves
282 north-south network performance (that is, traffic with endpoints outside the host machine) by allowing
283 traffic to bypass the host machine’s network stack.</para>
284
285 <variablelist class='network-directives'>
286 <varlistentry>
287 <term><varname>VirtualFunction=</varname></term>
288 <listitem>
289 <para>Specifies a Virtual Function (VF), lightweight PCIe function designed solely to move data
290 in and out. Takes an unsigned integer in the range 0…2147483646. This option is compulsory.</para>
291 </listitem>
292 </varlistentry>
293
294 <varlistentry>
295 <term><varname>VLANId=</varname></term>
296 <listitem>
297 <para>Specifies VLAN ID of the virtual function. Takes an unsigned integer in the range 1…4095.</para>
298 </listitem>
299 </varlistentry>
300
301 <varlistentry>
302 <term><varname>QualityOfService=</varname></term>
303 <listitem>
304 <para>Specifies quality of service of the virtual function. Takes an unsigned integer in the range 1…4294967294.</para>
305 </listitem>
306 </varlistentry>
307
308 <varlistentry>
309 <term><varname>VLANProtocol=</varname></term>
310 <listitem>
311 <para>Specifies VLAN protocol of the virtual function. Takes <literal>802.1Q</literal> or
312 <literal>802.1ad</literal>.</para>
313 </listitem>
314 </varlistentry>
315
316 <varlistentry>
317 <term><varname>MACSpoofCheck=</varname></term>
318 <listitem>
319 <para>Takes a boolean. Controls the MAC spoof checking. When unset, the kernel's default will be used.</para>
320 </listitem>
321 </varlistentry>
322
323 <varlistentry>
324 <term><varname>QueryReceiveSideScaling=</varname></term>
325 <listitem>
326 <para>Takes a boolean. Toggle the ability of querying the receive side scaling (RSS)
327 configuration of the virtual function (VF). The VF RSS information like RSS hash key may be
328 considered sensitive on some devices where this information is shared between VF and the
329 physical function (PF). When unset, the kernel's default will be used.</para>
330 </listitem>
331 </varlistentry>
332
333 <varlistentry>
334 <term><varname>Trust=</varname></term>
335 <listitem>
336 <para>Takes a boolean. Allows to set trust mode of the virtual function (VF). When set, VF
337 users can set a specific feature which may impact security and/or performance. When unset,
338 the kernel's default will be used.</para>
339 </listitem>
340 </varlistentry>
341
342 <varlistentry>
343 <term><varname>LinkState=</varname></term>
344 <listitem>
345 <para>Allows to set the link state of the virtual function (VF). Takes a boolean or a
346 special value <literal>auto</literal>. Setting to <literal>auto</literal> means a
347 reflection of the physical function (PF) link state, <literal>yes</literal> lets the VF to
348 communicate with other VFs on this host even if the PF link state is down,
349 <literal>no</literal> causes the hardware to drop any packets sent by the VF. When unset,
350 the kernel's default will be used.</para>
351 </listitem>
352 </varlistentry>
353
354 <varlistentry>
355 <term><varname>MACAddress=</varname></term>
356 <listitem>
357 <para>Specifies the MAC address for the virtual function.</para>
358 </listitem>
359 </varlistentry>
360 </variablelist>
361 </refsect1>
362
363 <refsect1>
364 <title>[Network] Section Options</title>
365
366 <para>The [Network] section accepts the following keys:</para>
367
368 <variablelist class='network-directives'>
369 <varlistentry>
370 <term><varname>Description=</varname></term>
371 <listitem>
372 <para>A description of the device. This is only used for
373 presentation purposes.</para>
374 </listitem>
375 </varlistentry>
376 <varlistentry>
377 <term><varname>DHCP=</varname></term>
378 <listitem>
379 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
380 <literal>yes</literal>, <literal>no</literal>,
381 <literal>ipv4</literal>, or <literal>ipv6</literal>. Defaults
382 to <literal>no</literal>.</para>
383
384 <para>Note that DHCPv6 will by default be triggered by Router
385 Advertisement, if that is enabled, regardless of this parameter.
386 By enabling DHCPv6 support explicitly, the DHCPv6 client will
387 be started regardless of the presence of routers on the link,
388 or what flags the routers pass. See
389 <literal>IPv6AcceptRA=</literal>.</para>
390
391 <para>Furthermore, note that by default the domain name
392 specified through DHCP is not used for name resolution.
393 See option <option>UseDomains=</option> below.</para>
394
395 <para>See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the DHCP
396 client support.</para>
397 </listitem>
398 </varlistentry>
399 <varlistentry>
400 <term><varname>DHCPServer=</varname></term>
401 <listitem>
402 <para>Takes a boolean. If set to <literal>yes</literal>, DHCPv4 server will be started. Defaults
403 to <literal>no</literal>. Further settings for the DHCP server may be set in the [DHCPServer]
404 section described below.</para>
405 </listitem>
406 </varlistentry>
407 <varlistentry>
408 <term><varname>LinkLocalAddressing=</varname></term>
409 <listitem>
410 <para>Enables link-local address autoconfiguration. Accepts <option>yes</option>,
411 <option>no</option>, <option>ipv4</option>, and <option>ipv6</option>. An IPv6 link-local address
412 is configured when <option>yes</option> or <option>ipv6</option>. An IPv4 link-local address is
413 configured when <option>yes</option> or <option>ipv4</option> and when DHCPv4 autoconfiguration
414 has been unsuccessful for some time. (IPv4 link-local address autoconfiguration will usually
415 happen in parallel with repeated attempts to acquire a DHCPv4 lease).</para>
416
417 <para>Defaults to <option>no</option> when <varname>Bridge=yes</varname> is set, and
418 <option>ipv6</option> otherwise.</para>
419 </listitem>
420 </varlistentry>
421 <varlistentry>
422 <term><varname>IPv6LinkLocalAddressGenerationMode=</varname></term>
423 <listitem>
424 <para>Specifies how IPv6 link local address is generated. Takes one of <literal>eui64</literal>,
425 <literal>none</literal>, <literal>stable-privacy</literal> and <literal>random</literal>.
426 When unset, the kernel's default will be used. Note that if <varname>LinkLocalAdressing=</varname>
427 not configured as <literal>ipv6</literal> then <varname>IPv6LinkLocalAddressGenerationMode=</varname>
428 is ignored.</para>
429 </listitem>
430 </varlistentry>
431 <varlistentry>
432 <term><varname>IPv4LLRoute=</varname></term>
433 <listitem>
434 <para>Takes a boolean. If set to true, sets up the route needed for
435 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
436 to false.
437 </para>
438 </listitem>
439 </varlistentry>
440 <varlistentry>
441 <term><varname>DefaultRouteOnDevice=</varname></term>
442 <listitem>
443 <para>Takes a boolean. If set to true, sets up the default route bound to the interface.
444 Defaults to false. This is useful when creating routes on point-to-point interfaces.
445 This is equivalent to e.g. the following.
446 <programlisting>ip route add default dev veth99</programlisting></para>
447 </listitem>
448 </varlistentry>
449 <varlistentry>
450 <term><varname>IPv6Token=</varname></term>
451 <listitem>
452 <para>Specifies an optional address generation mode for the Stateless Address
453 Autoconfiguration (SLAAC). Supported modes are <literal>prefixstable</literal> and
454 <literal>static</literal>.</para>
455
456 <para>When the mode is set to <literal>static</literal>, an IPv6 address must be
457 specified after a colon (<literal>:</literal>), and the lower bits of the supplied
458 address are combined with the upper bits of a prefix received in a Router Advertisement
459 (RA) message to form a complete address. Note that if multiple prefixes are received in an
460 RA message, or in multiple RA messages, addresses will be formed from each of them using
461 the supplied address. This mode implements SLAAC but uses a static interface identifier
462 instead of an identifier generated by using the EUI-64 algorithm. Because the interface
463 identifier is static, if Duplicate Address Detection detects that the computed address is a
464 duplicate (in use by another node on the link), then this mode will fail to provide an
465 address for that prefix. If an IPv6 address without mode is specified, then
466 <literal>static</literal> mode is assumed.</para>
467
468 <para>When the mode is set to <literal>prefixstable</literal> the
469 <ulink url="https://tools.ietf.org/html/rfc7217">RFC 7217</ulink> algorithm for generating
470 interface identifiers will be used. This mode can optionally take an IPv6 address separated
471 with a colon (<literal>:</literal>). If an IPv6 address is specified, then an interface
472 identifier is generated only when a prefix received in an RA message matches the supplied
473 address.</para>
474
475 <para>If no address generation mode is specified (which is the default), or a received
476 prefix does not match any of the addresses provided in <literal>prefixstable</literal>
477 mode, then the EUI-64 algorithm will be used to form an interface identifier for that
478 prefix. This mode is also SLAAC, but with a potentially stable interface identifier which
479 does not directly map to the interface's hardware address.</para>
480
481 <para>Note that the <literal>prefixstable</literal> algorithm uses both the interface
482 name and MAC address as input to the hash to compute the interface identifier, so if either
483 of those are changed the resulting interface identifier (and address) will change, even if
484 the prefix received in the RA message has not changed.</para>
485
486 <para>This setting can be specified multiple times. If an empty string is assigned, then
487 the all previous assignments are cleared.</para>
488
489 <para>Examples:
490 <programlisting>IPv6Token=::1a:2b:3c:4d
491 IPv6Token=static:::1a:2b:3c:4d
492 IPv6Token=prefixstable
493 IPv6Token=prefixstable:2002:da8:1::</programlisting></para>
494 </listitem>
495 </varlistentry>
496 <varlistentry>
497 <term><varname>LLMNR=</varname></term>
498 <listitem>
499 <para>Takes a boolean or <literal>resolve</literal>. When true,
500 enables <ulink
501 url="https://tools.ietf.org/html/rfc4795">Link-Local
502 Multicast Name Resolution</ulink> on the link. When set to
503 <literal>resolve</literal>, only resolution is enabled,
504 but not host registration and announcement. Defaults to
505 true. This setting is read by
506 <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
507 </listitem>
508 </varlistentry>
509 <varlistentry>
510 <term><varname>MulticastDNS=</varname></term>
511 <listitem>
512 <para>Takes a boolean or <literal>resolve</literal>. When true,
513 enables <ulink
514 url="https://tools.ietf.org/html/rfc6762">Multicast
515 DNS</ulink> support on the link. When set to
516 <literal>resolve</literal>, only resolution is enabled,
517 but not host or service registration and
518 announcement. Defaults to false. This setting is read by
519 <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
520 </listitem>
521 </varlistentry>
522 <varlistentry>
523 <term><varname>DNSOverTLS=</varname></term>
524 <listitem>
525 <para>Takes a boolean or <literal>opportunistic</literal>.
526 When true, enables
527 <ulink
528 url="https://tools.ietf.org/html/rfc7858">DNS-over-TLS</ulink>
529 support on the link.
530 When set to <literal>opportunistic</literal>, compatibility with
531 non-DNS-over-TLS servers is increased, by automatically
532 turning off DNS-over-TLS servers in this case.
533 This option defines a per-interface setting for
534 <citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
535 global <varname>DNSOverTLS=</varname> option. Defaults to
536 false. This setting is read by
537 <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
538 </listitem>
539 </varlistentry>
540 <varlistentry>
541 <term><varname>DNSSEC=</varname></term>
542 <listitem>
543 <para>Takes a boolean or <literal>allow-downgrade</literal>. When true, enables
544 <ulink url="https://tools.ietf.org/html/rfc4033">DNSSEC</ulink>
545 DNS validation support on the link. When set to
546 <literal>allow-downgrade</literal>, compatibility with
547 non-DNSSEC capable networks is increased, by automatically
548 turning off DNSSEC in this case. This option defines a
549 per-interface setting for
550 <citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
551 global <varname>DNSSEC=</varname> option. Defaults to
552 false. This setting is read by
553 <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
554 </listitem>
555 </varlistentry>
556 <varlistentry>
557 <term><varname>DNSSECNegativeTrustAnchors=</varname></term>
558 <listitem><para>A space-separated list of DNSSEC negative
559 trust anchor domains. If specified and DNSSEC is enabled,
560 look-ups done via the interface's DNS server will be subject
561 to the list of negative trust anchors, and not require
562 authentication for the specified domains, or anything below
563 it. Use this to disable DNSSEC authentication for specific
564 private domains, that cannot be proven valid using the
565 Internet DNS hierarchy. Defaults to the empty list. This
566 setting is read by
567 <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
568 </listitem>
569 </varlistentry>
570 <varlistentry>
571 <term><varname>LLDP=</varname></term>
572 <listitem>
573 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
574 implemented on professional routers and bridges which announces which physical port a system is connected
575 to, as well as other related data. Accepts a boolean or the special value
576 <literal>routers-only</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
577 neighbors maintained. If <literal>routers-only</literal> is set only LLDP data of various types of routers
578 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
579 others). If false, LLDP reception is disabled. Defaults to <literal>routers-only</literal>. Use
580 <citerefentry><refentrytitle>networkctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
581 collected neighbor data. LLDP is only available on Ethernet links. See <varname>EmitLLDP=</varname> below
582 for enabling LLDP packet emission from the local system.
583 </para>
584 </listitem>
585 </varlistentry>
586 <varlistentry>
587 <term><varname>EmitLLDP=</varname></term>
588 <listitem>
589 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
590 <literal>nearest-bridge</literal>, <literal>non-tpmr-bridge</literal> and
591 <literal>customer-bridge</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
592 a short LLDP packet with information about the local system is sent out in regular intervals on the
593 link. The LLDP packet will contain information about the local hostname, the local machine ID (as stored
594 in <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
595 local interface name, as well as the pretty hostname of the system (as set in
596 <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
597 emission is only available on Ethernet links. Note that this setting passes data suitable for
598 identification of host to the network and should thus not be enabled on untrusted networks, where such
599 identification data should not be made available. Use this option to permit other systems to identify on
600 which interfaces they are connected to this system. The three special values control propagation of the
601 LLDP packets. The <literal>nearest-bridge</literal> setting permits propagation only to the nearest
602 connected bridge, <literal>non-tpmr-bridge</literal> permits propagation across Two-Port MAC Relays, but
603 not any other bridges, and <literal>customer-bridge</literal> permits propagation until a customer bridge
604 is reached. For details about these concepts, see <ulink
605 url="https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE 802.1AB-2016</ulink>. Note that
606 configuring this setting to true is equivalent to <literal>nearest-bridge</literal>, the recommended and
607 most restricted level of propagation. See <varname>LLDP=</varname> above for an option to enable LLDP
608 reception.</para>
609 </listitem>
610 </varlistentry>
611
612 <varlistentry>
613 <term><varname>BindCarrier=</varname></term>
614 <listitem>
615 <para>A link name or a list of link names. When set, controls the behavior of the current
616 link. When all links in the list are in an operational down state, the current link is brought
617 down. When at least one link has carrier, the current interface is brought up.</para>
618
619 <para>This forces <varname>ActivationPolicy=</varname> to be set to <literal>bound</literal>.</para>
620 </listitem>
621 </varlistentry>
622 <varlistentry>
623 <term><varname>Address=</varname></term>
624 <listitem>
625 <para>A static IPv4 or IPv6 address and its prefix length,
626 separated by a <literal>/</literal> character. Specify
627 this key more than once to configure several addresses.
628 The format of the address must be as described in
629 <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
630 This is a short-hand for an [Address] section only
631 containing an Address key (see below). This option may be
632 specified more than once.
633 </para>
634
635 <para>If the specified address is <literal>0.0.0.0</literal> (for IPv4) or <literal>::</literal>
636 (for IPv6), a new address range of the requested size is automatically allocated from a
637 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than 8 for
638 IPv4, and 64 for IPv6. The allocated range is checked against all current network interfaces and
639 all known network configuration files to avoid address range conflicts. The default system-wide
640 pool consists of 192.168.0.0/16, 172.16.0.0/12 and 10.0.0.0/8 for IPv4, and fd00::/8 for IPv6.
641 This functionality is useful to manage a large number of dynamically created network interfaces
642 with the same network configuration and automatic address range assignment.</para>
643
644 </listitem>
645 </varlistentry>
646 <varlistentry>
647 <term><varname>Gateway=</varname></term>
648 <listitem>
649 <para>The gateway address, which must be in the format
650 described in
651 <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
652 This is a short-hand for a [Route] section only containing
653 a Gateway key. This option may be specified more than
654 once.</para>
655 </listitem>
656 </varlistentry>
657 <varlistentry>
658 <term><varname>DNS=</varname></term>
659 <listitem>
660 <para>A DNS server address, which must be in the format described in
661 <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
662 This option may be specified more than once. Each address can optionally take a port number
663 separated with <literal>:</literal>, a network interface name or index separated with
664 <literal>%</literal>, and a Server Name Indication (SNI) separated with <literal>#</literal>.
665 When IPv6 address is specified with a port number, then the address must be in the square
666 brackets. That is, the acceptable full formats are
667 <literal>111.222.333.444:9953%ifname#example.com</literal> for IPv4 and
668 <literal>[1111:2222::3333]:9953%ifname#example.com</literal> for IPv6. If an empty string is
669 assigned, then the all previous assignments are cleared. This setting is read by
670 <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
671 </listitem>
672 </varlistentry>
673 <varlistentry>
674 <term><varname>Domains=</varname></term>
675 <listitem>
676 <para>A whitespace-separated list of domains which should be resolved using the DNS servers on
677 this link. Each item in the list should be a domain name, optionally prefixed with a tilde
678 (<literal>~</literal>). The domains with the prefix are called "routing-only domains". The
679 domains without the prefix are called "search domains" and are first used as search suffixes for
680 extending single-label hostnames (hostnames containing no dots) to become fully qualified
681 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
682 specified search domains are appended to it in turn, converting it into a fully qualified domain
683 name, until one of them may be successfully resolved.</para>
684
685 <para>Both "search" and "routing-only" domains are used for routing of DNS queries: look-ups for hostnames
686 ending in those domains (hence also single label names, if any "search domains" are listed), are routed to
687 the DNS servers configured for this interface. The domain routing logic is particularly useful on
688 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.</para>
689
690 <para>The "routing-only" domain <literal>~.</literal> (the tilde indicating definition of a routing domain,
691 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
692 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
693 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
694 if a link on which they are connected is available.</para>
695
696 <para>This setting is read by
697 <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
698 "Search domains" correspond to the <varname>domain</varname> and <varname>search</varname> entries in
699 <citerefentry project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
700 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
701 name servers limited to a specific link.</para>
702 </listitem>
703 </varlistentry>
704 <varlistentry>
705 <term><varname>DNSDefaultRoute=</varname></term>
706 <listitem>
707 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
708 names that do not match any link's configured <varname>Domains=</varname> setting. If false, this link's
709 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
710 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
711 queries not matching any link's configured domains will be routed to this link if it has no routing-only
712 domains configured.</para>
713 </listitem>
714 </varlistentry>
715 <varlistentry>
716 <term><varname>NTP=</varname></term>
717 <listitem>
718 <para>An NTP server address (either an IP address, or a hostname). This option may be specified more than once. This setting is read by
719 <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
720 </listitem>
721 </varlistentry>
722 <varlistentry>
723 <term><varname>IPForward=</varname></term>
724 <listitem><para>Configures IP packet forwarding for the
725 system. If enabled, incoming packets on any network
726 interface will be forwarded to any other interfaces
727 according to the routing table. Takes a boolean,
728 or the values <literal>ipv4</literal> or
729 <literal>ipv6</literal>, which only enable IP packet
730 forwarding for the specified address family. This controls
731 the <filename>net.ipv4.ip_forward</filename> and
732 <filename>net.ipv6.conf.all.forwarding</filename> sysctl
733 options of the network interface (see <ulink
734 url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink>
735 for details about sysctl options). Defaults to
736 <literal>no</literal>.</para>
737
738 <para>Note: this setting controls a global kernel option,
739 and does so one way only: if a network that has this setting
740 enabled is set up the global setting is turned on. However,
741 it is never turned off again, even after all networks with
742 this setting enabled are shut down again.</para>
743
744 <para>To allow IP packet forwarding only between specific
745 network interfaces use a firewall.</para>
746 </listitem>
747 </varlistentry>
748 <varlistentry>
749 <term><varname>IPMasquerade=</varname></term>
750 <listitem><para>Configures IP masquerading for the network interface. If enabled, packets
751 forwarded from the network interface will be appear as coming from the local host. Takes one
752 of <literal>ipv4</literal>, <literal>ipv6</literal>, <literal>both</literal>, or
753 <literal>no</literal>. Defaults to <literal>no</literal>. If enabled, this automatically sets
754 <varname>IPForward=</varname> to one of <literal>ipv4</literal>, <literal>ipv6</literal> or
755 <literal>yes</literal>.</para>
756 <para>Note. Any positive boolean values such as <literal>yes</literal> or
757 <literal>true</literal> are now deprecated. Please use one of the values in the above.</para>
758 </listitem>
759 </varlistentry>
760 <varlistentry>
761 <term><varname>IPv6PrivacyExtensions=</varname></term>
762 <listitem><para>Configures use of stateless temporary
763 addresses that change over time (see <ulink
764 url="https://tools.ietf.org/html/rfc4941">RFC 4941</ulink>,
765 Privacy Extensions for Stateless Address Autoconfiguration
766 in IPv6). Takes a boolean or the special values
767 <literal>prefer-public</literal> and
768 <literal>kernel</literal>. When true, enables the privacy
769 extensions and prefers temporary addresses over public
770 addresses. When <literal>prefer-public</literal>, enables the
771 privacy extensions, but prefers public addresses over
772 temporary addresses. When false, the privacy extensions
773 remain disabled. When <literal>kernel</literal>, the kernel's
774 default setting will be left in place. Defaults to
775 <literal>no</literal>.</para></listitem>
776 </varlistentry>
777 <varlistentry>
778 <term><varname>IPv6AcceptRA=</varname></term>
779 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
780 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they may
781 trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or if no
782 routers are found on the link. The default is to disable RA reception for bridge devices or when IP
783 forwarding is enabled, and to enable it otherwise. Cannot be enabled on bond devices and when link
784 local addressing is disabled.</para>
785
786 <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA] section, see
787 below.</para>
788
789 <para>Also see <ulink
790 url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink> in the kernel
791 documentation regarding <literal>accept_ra</literal>, but note that systemd's setting of
792 <constant>1</constant> (i.e. true) corresponds to kernel's setting of <constant>2</constant>.</para>
793
794 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
795 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
796 RA protocol is used, and the kernel's own implementation remains disabled, since
797 <command>systemd-networkd</command> needs to know all details supplied in the advertisements,
798 and these are not available from the kernel if the kernel's own implementation is used.</para>
799 </listitem>
800 </varlistentry>
801 <varlistentry>
802 <term><varname>IPv6DuplicateAddressDetection=</varname></term>
803 <listitem><para>Configures the amount of IPv6 Duplicate
804 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
805 </para></listitem>
806 </varlistentry>
807 <varlistentry>
808 <term><varname>IPv6HopLimit=</varname></term>
809 <listitem><para>Configures IPv6 Hop Limit. For each router that
810 forwards the packet, the hop limit is decremented by 1. When the
811 hop limit field reaches zero, the packet is discarded.
812 When unset, the kernel's default will be used.
813 </para></listitem>
814 </varlistentry>
815 <varlistentry>
816 <term><varname>IPv4AcceptLocal=</varname></term>
817 <listitem><para>Takes a boolean. Accept packets with local source addresses. In combination
818 with suitable routing, this can be used to direct packets between two local interfaces over
819 the wire and have them accepted properly. When unset, the kernel's default will be used.
820 </para></listitem>
821 </varlistentry>
822 <varlistentry>
823 <term><varname>IPv4RouteLocalnet=</varname></term>
824 <listitem><para>Takes a boolean. When true, the kernel does not consider loopback addresses as martian source or destination
825 while routing. This enables the use of 127.0.0.0/8 for local routing purposes. When unset, the kernel's default will be used.
826 </para></listitem>
827 </varlistentry>
828 <varlistentry>
829 <term><varname>IPv4ProxyARP=</varname></term>
830 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
831 usually a router, answers ARP requests intended for another machine. By "faking" its identity,
832 the router accepts responsibility for routing packets to the "real" destination. See <ulink
833 url="https://tools.ietf.org/html/rfc1027">RFC 1027</ulink>.
834 When unset, the kernel's default will be used.
835 </para></listitem>
836 </varlistentry>
837 <varlistentry>
838 <term><varname>IPv6ProxyNDP=</varname></term>
839 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
840 Protocol) is a technique for IPv6 to allow routing of addresses to a different
841 destination when peers expect them to be present on a certain physical link.
842 In this case a router answers Neighbour Advertisement messages intended for
843 another machine by offering its own MAC address as destination.
844 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
845 Advertisement messages for addresses in the IPv6 neighbor proxy table,
846 which can also be shown by <command>ip -6 neighbour show proxy</command>.
847 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
848 interface depending on this option.
849 When unset, the kernel's default will be used.
850 </para></listitem>
851 </varlistentry>
852 <varlistentry>
853 <term><varname>IPv6ProxyNDPAddress=</varname></term>
854 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
855 proxied. This option may be specified more than once. systemd-networkd will add the
856 <option>IPv6ProxyNDPAddress=</option> entries to the kernel's IPv6 neighbor proxy table.
857 This option implies <option>IPv6ProxyNDP=yes</option> but has no effect if
858 <option>IPv6ProxyNDP</option> has been set to false. When unset, the kernel's default will be used.
859 </para></listitem>
860 </varlistentry>
861 <varlistentry>
862 <term><varname>IPv6SendRA=</varname></term>
863 <listitem><para>Whether to enable or disable Router Advertisement sending on a link. Takes a
864 boolean value. When enabled, prefixes configured in [IPv6Prefix] sections and routes
865 configured in [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA]
866 section. If <varname>DHCPv6PrefixDelegation=</varname> is enabled, then the delegated
867 prefixes are also distributed. See <varname>DHCPv6PrefixDelegation=</varname> setting and the
868 [IPv6SendRA], [IPv6Prefix], [IPv6RoutePrefix], and [DHCPv6PrefixDelegation] sections for more
869 configuration options.</para></listitem>
870 </varlistentry>
871 <varlistentry>
872 <term><varname>DHCPv6PrefixDelegation=</varname></term>
873 <listitem><para>Takes a boolean value. When enabled, requests prefixes using a DHCPv6 client
874 configured on another link. By default, an address within each delegated prefix will be
875 assigned, and the prefixes will be announced through IPv6 Router Advertisement when
876 <varname>IPv6SendRA=</varname> is enabled. Such default settings can be configured in
877 [DHCPv6PrefixDelegation] section. Defaults to disabled.</para></listitem>
878 </varlistentry>
879 <varlistentry>
880 <term><varname>IPv6MTUBytes=</varname></term>
881 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
882 An integer greater than or equal to 1280 bytes. When unset, the kernel's default will be used.
883 </para></listitem>
884 </varlistentry>
885 <varlistentry>
886 <term><varname>Bridge=</varname></term>
887 <listitem>
888 <para>The name of the bridge to add the link to. See
889 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
890 </para>
891 </listitem>
892 </varlistentry>
893 <varlistentry>
894 <term><varname>Bond=</varname></term>
895 <listitem>
896 <para>The name of the bond to add the link to. See
897 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
898 </para>
899 </listitem>
900 </varlistentry>
901 <varlistentry>
902 <term><varname>VRF=</varname></term>
903 <listitem>
904 <para>The name of the VRF to add the link to. See
905 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
906 </para>
907 </listitem>
908 </varlistentry>
909 <varlistentry>
910 <term><varname>VLAN=</varname></term>
911 <listitem>
912 <para>The name of a VLAN to create on the link. See
913 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
914 This option may be specified more than once.</para>
915 </listitem>
916 </varlistentry>
917 <varlistentry>
918 <term><varname>IPVLAN=</varname></term>
919 <listitem>
920 <para>The name of a IPVLAN to create on the link. See
921 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
922 This option may be specified more than once.</para>
923 </listitem>
924 </varlistentry>
925 <varlistentry>
926 <term><varname>MACVLAN=</varname></term>
927 <listitem>
928 <para>The name of a MACVLAN to create on the link. See
929 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
930 This option may be specified more than once.</para>
931 </listitem>
932 </varlistentry>
933 <varlistentry>
934 <term><varname>VXLAN=</varname></term>
935 <listitem>
936 <para>The name of a VXLAN to create on the link. See
937 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
938 This option may be specified more than once.</para>
939 </listitem>
940 </varlistentry>
941 <varlistentry>
942 <term><varname>Tunnel=</varname></term>
943 <listitem>
944 <para>The name of a Tunnel to create on the link. See
945 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
946 This option may be specified more than once.</para>
947 </listitem>
948 </varlistentry>
949 <varlistentry>
950 <term><varname>MACsec=</varname></term>
951 <listitem>
952 <para>The name of a MACsec device to create on the link. See
953 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
954 This option may be specified more than once.</para>
955 </listitem>
956 </varlistentry>
957 <varlistentry>
958 <term><varname>ActiveSlave=</varname></term>
959 <listitem>
960 <para>Takes a boolean. Specifies the new active slave. The <literal>ActiveSlave=</literal>
961 option is only valid for following modes:
962 <literal>active-backup</literal>,
963 <literal>balance-alb</literal> and
964 <literal>balance-tlb</literal>. Defaults to false.
965 </para>
966 </listitem>
967 </varlistentry>
968 <varlistentry>
969 <term><varname>PrimarySlave=</varname></term>
970 <listitem>
971 <para>Takes a boolean. Specifies which slave is the primary device. The specified
972 device will always be the active slave while it is available. Only when the
973 primary is off-line will alternate devices be used. This is useful when
974 one slave is preferred over another, e.g. when one slave has higher throughput
975 than another. The <literal>PrimarySlave=</literal> option is only valid for
976 following modes:
977 <literal>active-backup</literal>,
978 <literal>balance-alb</literal> and
979 <literal>balance-tlb</literal>. Defaults to false.
980 </para>
981 </listitem>
982 </varlistentry>
983 <varlistentry>
984 <term><varname>ConfigureWithoutCarrier=</varname></term>
985 <listitem>
986 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
987 Defaults to false. If <option>IgnoreCarrierLoss=</option> is not explicitly set, it will
988 default to this value.
989 </para>
990 </listitem>
991 </varlistentry>
992 <varlistentry>
993 <term><varname>IgnoreCarrierLoss=</varname></term>
994 <listitem>
995 <para>Takes a boolean. Allows networkd to retain both the static and dynamic configuration
996 of the interface even if its carrier is lost. When unset, the value specified with
997 <option>ConfigureWithoutCarrier=</option> is used.
998 </para>
999
1000 <para>When <varname>ActivationPolicy=</varname> is set to <literal>always-up</literal>, this
1001 is forced to <literal>true</literal>.
1002 </para>
1003 </listitem>
1004 </varlistentry>
1005 <varlistentry>
1006 <term><varname>Xfrm=</varname></term>
1007 <listitem>
1008 <para>The name of the xfrm to create on the link. See
1009 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1010 This option may be specified more than once.</para>
1011 </listitem>
1012 </varlistentry>
1013 <varlistentry>
1014 <term><varname>KeepConfiguration=</varname></term>
1015 <listitem>
1016 <para>Takes a boolean or one of <literal>static</literal>, <literal>dhcp-on-stop</literal>,
1017 <literal>dhcp</literal>. When <literal>static</literal>, <command>systemd-networkd</command>
1018 will not drop static addresses and routes on starting up process. When set to
1019 <literal>dhcp-on-stop</literal>, <command>systemd-networkd</command> will not drop addresses
1020 and routes on stopping the daemon. When <literal>dhcp</literal>,
1021 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
1022 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
1023 e.g., the root filesystem relies on this connection. The setting <literal>dhcp</literal>
1024 implies <literal>dhcp-on-stop</literal>, and <literal>yes</literal> implies
1025 <literal>dhcp</literal> and <literal>static</literal>. Defaults to <literal>no</literal>.
1026 </para>
1027 </listitem>
1028 </varlistentry>
1029 <varlistentry>
1030 <term><varname>BatmanAdvanced=</varname></term>
1031 <listitem>
1032 <para>The name of the B.A.T.M.A.N. Advanced interface to add the link to. See
1033 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1034 </para>
1035 </listitem>
1036 </varlistentry>
1037 </variablelist>
1038
1039 </refsect1>
1040
1041 <refsect1>
1042 <title>[Address] Section Options</title>
1043
1044 <para>An [Address] section accepts the following keys. Specify several [Address]
1045 sections to configure several addresses.</para>
1046
1047 <variablelist class='network-directives'>
1048 <varlistentry>
1049 <term><varname>Address=</varname></term>
1050 <listitem>
1051 <para>As in the [Network] section. This key is mandatory. Each [Address] section can contain one
1052 <varname>Address=</varname> setting.</para>
1053 </listitem>
1054 </varlistentry>
1055 <varlistentry>
1056 <term><varname>Peer=</varname></term>
1057 <listitem>
1058 <para>The peer address in a point-to-point connection.
1059 Accepts the same format as the <varname>Address=</varname>
1060 key.</para>
1061 </listitem>
1062 </varlistentry>
1063 <varlistentry>
1064 <term><varname>Broadcast=</varname></term>
1065 <listitem>
1066 <para>Takes an IPv4 address or boolean value. The address must be in the format described in
1067 <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1068 If set to true, then the IPv4 broadcast address will be derived from the
1069 <varname>Address=</varname> setting. If set to false, then the broadcast address will not
1070 be set. Defaults to true, except for wireguard interfaces, where it default to false.
1071 </para>
1072 </listitem>
1073 </varlistentry>
1074 <varlistentry>
1075 <term><varname>Label=</varname></term>
1076 <listitem>
1077 <para>An address label.</para>
1078 </listitem>
1079 </varlistentry>
1080 <varlistentry>
1081 <term><varname>PreferredLifetime=</varname></term>
1082 <listitem>
1083 <para>Allows the default "preferred lifetime" of the address to be overridden. Only three
1084 settings are accepted: <literal>forever</literal>, <literal>infinity</literal>, which is the
1085 default and means that the address never expires, and <literal>0</literal>, which means that the
1086 address is considered immediately "expired" and will not be used, unless explicitly requested. A
1087 setting of <option>PreferredLifetime=0</option> is useful for addresses which are added to be
1088 used only by a specific application, which is then configured to use them explicitly.</para>
1089 </listitem>
1090 </varlistentry>
1091 <varlistentry>
1092 <term><varname>Scope=</varname></term>
1093 <listitem>
1094 <para>The scope of the address, which can be
1095 <literal>global</literal> (valid everywhere on the network, even through a gateway),
1096 <literal>link</literal> (only valid on this device, will not traverse a gateway) or
1097 <literal>host</literal> (only valid within the device itself, e.g. 127.0.0.1)
1098 or an unsigned integer in the range 0…255.
1099 Defaults to <literal>global</literal>.</para>
1100 </listitem>
1101 </varlistentry>
1102 <varlistentry>
1103 <term><varname>HomeAddress=</varname></term>
1104 <listitem>
1105 <para>Takes a boolean. Designates this address the "home address" as defined in
1106 <ulink url="https://tools.ietf.org/html/rfc6275">RFC 6275</ulink>.
1107 Supported only on IPv6. Defaults to false.</para>
1108 </listitem>
1109 </varlistentry>
1110 <varlistentry>
1111 <term><varname>DuplicateAddressDetection=</varname></term>
1112 <listitem>
1113 <para>Takes one of <literal>ipv4</literal>, <literal>ipv6</literal>,
1114 <literal>both</literal>, <literal>none</literal>. When <literal>ipv4</literal>,
1115 performs IPv4 Duplicate Address Detection. See
1116 <ulink url="https://tools.ietf.org/html/rfc5227">RFC 5224</ulink>.
1117 When <literal>ipv6</literal>, performs IPv6 Duplicate Address Detection. See
1118 <ulink url="https://tools.ietf.org/html/rfc4862">RFC 4862</ulink>.
1119 Defaults to <literal>ipv6</literal>.</para>
1120 </listitem>
1121 </varlistentry>
1122 <varlistentry>
1123 <term><varname>ManageTemporaryAddress=</varname></term>
1124 <listitem>
1125 <para>Takes a boolean. If true the kernel manage temporary addresses created
1126 from this one as template on behalf of Privacy Extensions
1127 <ulink url="https://tools.ietf.org/html/rfc3041">RFC 3041</ulink>. For this to become
1128 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
1129 The given address needs to have a prefix length of 64. This flag allows using privacy
1130 extensions in a manually configured network, just like if stateless auto-configuration
1131 was active. Defaults to false.</para>
1132 </listitem>
1133 </varlistentry>
1134 <varlistentry>
1135 <term><varname>AddPrefixRoute=</varname></term>
1136 <listitem>
1137 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
1138 Defaults to true.</para>
1139 </listitem>
1140 </varlistentry>
1141 <varlistentry>
1142 <term><varname>AutoJoin=</varname></term>
1143 <listitem>
1144 <para>Takes a boolean. Joining multicast group on ethernet level via
1145 <command>ip maddr</command> command would not work if we have an Ethernet switch that does
1146 IGMP snooping since the switch would not replicate multicast packets on ports that did not
1147 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
1148 <command>ip link add vxlan</command> or networkd's netdev kind vxlan have the group option
1149 that enables then to do the required join. By extending ip address command with option
1150 <literal>autojoin</literal> we can get similar functionality for openvswitch (OVS) vxlan
1151 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
1152 Defaults to <literal>no</literal>.</para>
1153 </listitem>
1154 </varlistentry>
1155 </variablelist>
1156 </refsect1>
1157
1158 <refsect1>
1159 <title>[Neighbor] Section Options</title>
1160 <para>A [Neighbor] section accepts the following keys. The neighbor section adds a permanent, static
1161 entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the links
1162 matched for the network. Specify several [Neighbor] sections to configure several static neighbors.
1163 </para>
1164
1165 <variablelist class='network-directives'>
1166 <varlistentry>
1167 <term><varname>Address=</varname></term>
1168 <listitem>
1169 <para>The IP address of the neighbor.</para>
1170 </listitem>
1171 </varlistentry>
1172 <varlistentry>
1173 <term><varname>LinkLayerAddress=</varname></term>
1174 <listitem>
1175 <para>The link layer address (MAC address or IP address) of the neighbor.</para>
1176 </listitem>
1177 </varlistentry>
1178 </variablelist>
1179 </refsect1>
1180
1181 <refsect1>
1182 <title>[IPv6AddressLabel] Section Options</title>
1183
1184 <para>An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel]
1185 sections to configure several address labels. IPv6 address labels are used for address selection. See
1186 <ulink url="https://tools.ietf.org/html/rfc3484">RFC 3484</ulink>. Precedence is managed by userspace,
1187 and only the label itself is stored in the kernel.</para>
1188
1189 <variablelist class='network-directives'>
1190 <varlistentry>
1191 <term><varname>Label=</varname></term>
1192 <listitem>
1193 <para>The label for the prefix, an unsigned integer in the range 0–4294967294.
1194 0xffffffff is reserved. This setting is mandatory.</para>
1195 </listitem>
1196 </varlistentry>
1197 <varlistentry>
1198 <term><varname>Prefix=</varname></term>
1199 <listitem>
1200 <para>IPv6 prefix is an address with a prefix length, separated by a slash <literal>/</literal> character.
1201 This key is mandatory. </para>
1202 </listitem>
1203 </varlistentry>
1204 </variablelist>
1205 </refsect1>
1206
1207 <refsect1>
1208 <title>[RoutingPolicyRule] Section Options</title>
1209
1210 <para>An [RoutingPolicyRule] section accepts the following keys. Specify several [RoutingPolicyRule]
1211 sections to configure several rules.</para>
1212
1213 <variablelist class='network-directives'>
1214 <varlistentry>
1215 <term><varname>TypeOfService=</varname></term>
1216 <listitem>
1217 <para>Takes a number between 0 and 255 that specifies the type of service to match.</para>
1218 </listitem>
1219 </varlistentry>
1220 <varlistentry>
1221 <term><varname>From=</varname></term>
1222 <listitem>
1223 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.</para>
1224 </listitem>
1225 </varlistentry>
1226 <varlistentry>
1227 <term><varname>To=</varname></term>
1228 <listitem>
1229 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.</para>
1230 </listitem>
1231 </varlistentry>
1232 <varlistentry>
1233 <term><varname>FirewallMark=</varname></term>
1234 <listitem>
1235 <para>Specifies the iptables firewall mark value to match (a number between 1 and
1236 4294967295). Optionally, the firewall mask (also a number between 1 and 4294967295) can be
1237 suffixed with a slash (<literal>/</literal>), e.g., <literal>7/255</literal>.</para>
1238 </listitem>
1239 </varlistentry>
1240 <varlistentry>
1241 <term><varname>Table=</varname></term>
1242 <listitem>
1243 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes one of predefined names
1244 <literal>default</literal>, <literal>main</literal>, and <literal>local</literal>, and names defined in <varname>RouteTable=</varname>
1245 in <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1246 or a number between 1 and 4294967295. Defaults to <literal>main</literal>.</para>
1247 </listitem>
1248 </varlistentry>
1249 <varlistentry>
1250 <term><varname>Priority=</varname></term>
1251 <listitem>
1252 <para>Specifies the priority of this rule. <varname>Priority=</varname> is an unsigned
1253 integer. Higher number means lower priority, and rules get processed in order of increasing number.</para>
1254 </listitem>
1255 </varlistentry>
1256 <varlistentry>
1257 <term><varname>IncomingInterface=</varname></term>
1258 <listitem>
1259 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.</para>
1260 </listitem>
1261 </varlistentry>
1262 <varlistentry>
1263 <term><varname>OutgoingInterface=</varname></term>
1264 <listitem>
1265 <para>Specifies the outgoing device to match. The outgoing interface is only available for packets originating from local sockets that are bound to a device.</para>
1266 </listitem>
1267 </varlistentry>
1268 <varlistentry>
1269 <term><varname>SourcePort=</varname></term>
1270 <listitem>
1271 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1272 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.</para>
1273 </listitem>
1274 </varlistentry>
1275 <varlistentry>
1276 <term><varname>DestinationPort=</varname></term>
1277 <listitem>
1278 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1279 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.</para>
1280 </listitem>
1281 </varlistentry>
1282 <varlistentry>
1283 <term><varname>IPProtocol=</varname></term>
1284 <listitem>
1285 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as <literal>tcp</literal>,
1286 <literal>udp</literal> or <literal>sctp</literal>, or IP protocol number such as <literal>6</literal> for <literal>tcp</literal> or
1287 <literal>17</literal> for <literal>udp</literal>.
1288 Defaults to unset.</para>
1289 </listitem>
1290 </varlistentry>
1291 <varlistentry>
1292 <term><varname>InvertRule=</varname></term>
1293 <listitem>
1294 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.</para>
1295 </listitem>
1296 </varlistentry>
1297 <varlistentry>
1298 <term><varname>Family=</varname></term>
1299 <listitem>
1300 <para>Takes a special value <literal>ipv4</literal>, <literal>ipv6</literal>, or
1301 <literal>both</literal>. By default, the address family is determined by the address
1302 specified in <varname>To=</varname> or <varname>From=</varname>. If neither
1303 <varname>To=</varname> nor <varname>From=</varname> are specified, then defaults to
1304 <literal>ipv4</literal>.</para>
1305 </listitem>
1306 </varlistentry>
1307 <varlistentry>
1308 <term><varname>User=</varname></term>
1309 <listitem>
1310 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1311 unset.</para>
1312 </listitem>
1313 </varlistentry>
1314 <varlistentry>
1315 <term><varname>SuppressPrefixLength=</varname></term>
1316 <listitem>
1317 <para>Takes a number <replaceable>N</replaceable> in the range 0…128 and rejects routing
1318 decisions that have a prefix length of <replaceable>N</replaceable> or less. Defaults to
1319 unset.</para>
1320 </listitem>
1321 </varlistentry>
1322 <varlistentry>
1323 <term><varname>Type=</varname></term>
1324 <listitem>
1325 <para>Specifies Routing Policy Database (RPDB) rule type. Takes one of <literal>blackhole</literal>,
1326 <literal>unreachable</literal> or <literal>prohibit</literal>.
1327 </para>
1328 </listitem>
1329 </varlistentry>
1330 </variablelist>
1331 </refsect1>
1332
1333 <refsect1>
1334 <title>[NextHop] Section Options</title>
1335 <para>The [NextHop] section is used to manipulate entries in the kernel's "nexthop" tables. The
1336 [NextHop] section accepts the following keys. Specify several [NextHop] sections to configure several
1337 hops.</para>
1338
1339 <variablelist class='network-directives'>
1340 <varlistentry>
1341 <term><varname>Id=</varname></term>
1342 <listitem>
1343 <para>The id of the next hop. Takes an unsigned integer in the range 1…4294967295. If left
1344 unspecified, then automatically chosen by kernel.</para>
1345 </listitem>
1346 </varlistentry>
1347 <varlistentry>
1348 <term><varname>Gateway=</varname></term>
1349 <listitem>
1350 <para>As in the [Network] section.</para>
1351 </listitem>
1352 </varlistentry>
1353 <varlistentry>
1354 <term><varname>Family=</varname></term>
1355 <listitem>
1356 <para>Takes one of the special values <literal>ipv4</literal> or <literal>ipv6</literal>.
1357 By default, the family is determined by the address specified in
1358 <varname>Gateway=</varname>. If <varname>Gateway=</varname> is not specified, then defaults
1359 to <literal>ipv4</literal>.</para>
1360 </listitem>
1361 </varlistentry>
1362 <varlistentry>
1363 <term><varname>OnLink=</varname></term>
1364 <listitem>
1365 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1366 reachable directly by the current machine (i.e., attached to the local network), so that we
1367 can insert the nexthop in the kernel table without it being complained about. Defaults to
1368 <literal>no</literal>.</para>
1369 </listitem>
1370 </varlistentry>
1371 <varlistentry>
1372 <term><varname>Blackhole=</varname></term>
1373 <listitem>
1374 <para>Takes a boolean. If enabled, packets to the corresponding routes are discarded
1375 silently, and <varname>Gateway=</varname> cannot be specified. Defaults to
1376 <literal>no</literal>.</para>
1377 </listitem>
1378 </varlistentry>
1379 </variablelist>
1380 </refsect1>
1381
1382 <refsect1>
1383 <title>[Route] Section Options</title>
1384 <para>The [Route] section accepts the following keys. Specify several [Route] sections to configure
1385 several routes.</para>
1386
1387 <variablelist class='network-directives'>
1388 <varlistentry>
1389 <term><varname>Gateway=</varname></term>
1390 <listitem>
1391 <para>Takes the gateway address or the special values <literal>_dhcp4</literal> and
1392 <literal>_ipv6ra</literal>. If <literal>_dhcp4</literal> or <literal>_ipv6ra</literal> is
1393 set, then the gateway address provided by DHCPv4 or IPv6 RA is used.</para>
1394 </listitem>
1395 </varlistentry>
1396 <varlistentry>
1397 <term><varname>GatewayOnLink=</varname></term>
1398 <listitem>
1399 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1400 reachable directly by the current machine (i.e., attached to the local network), so that we
1401 can insert the route in the kernel table without it being complained about. Defaults to
1402 <literal>no</literal>.</para>
1403 </listitem>
1404 </varlistentry>
1405 <varlistentry>
1406 <term><varname>Destination=</varname></term>
1407 <listitem>
1408 <para>The destination prefix of the route. Possibly
1409 followed by a slash and the prefix length. If omitted, a
1410 full-length host route is assumed.</para>
1411 </listitem>
1412 </varlistentry>
1413 <varlistentry>
1414 <term><varname>Source=</varname></term>
1415 <listitem>
1416 <para>The source prefix of the route. Possibly followed by
1417 a slash and the prefix length. If omitted, a full-length
1418 host route is assumed.</para>
1419 </listitem>
1420 </varlistentry>
1421 <varlistentry>
1422 <term><varname>Metric=</varname></term>
1423 <listitem>
1424 <para>The metric of the route (an unsigned integer).</para>
1425 </listitem>
1426 </varlistentry>
1427 <varlistentry>
1428 <term><varname>IPv6Preference=</varname></term>
1429 <listitem>
1430 <para>Specifies the route preference as defined in <ulink
1431 url="https://tools.ietf.org/html/rfc4191">RFC 4191</ulink> for Router Discovery messages. Which
1432 can be one of <literal>low</literal> the route has a lowest priority, <literal>medium</literal>
1433 the route has a default priority or <literal>high</literal> the route has a highest priority.
1434 </para>
1435 </listitem>
1436 </varlistentry>
1437 <varlistentry>
1438 <term><varname>Scope=</varname></term>
1439 <listitem>
1440 <para>The scope of the IPv4 route, which can be <literal>global</literal>, <literal>site</literal>,
1441 <literal>link</literal>, <literal>host</literal>, or
1442 <literal>nowhere</literal>:</para>
1443 <itemizedlist>
1444 <listitem><para><literal>global</literal> means the route can reach
1445 hosts more than one hop away.</para></listitem>
1446
1447 <listitem><para><literal>site</literal> means an interior route in
1448 the local autonomous system.</para></listitem>
1449
1450 <listitem><para><literal>link</literal> means the route can only
1451 reach hosts on the local network (one hop away).</para></listitem>
1452
1453 <listitem><para><literal>host</literal> means the route will not
1454 leave the local machine (used for internal addresses like
1455 127.0.0.1).</para></listitem>
1456
1457 <listitem><para><literal>nowhere</literal> means the destination
1458 doesn't exist.</para></listitem>
1459 </itemizedlist>
1460 <para>For IPv4 route, defaults to <literal>host</literal> if <varname>Type=</varname> is
1461 <literal>local</literal> or <literal>nat</literal>,
1462 and <literal>link</literal> if <varname>Type=</varname> is
1463 <literal>broadcast</literal>, <literal>multicast</literal>, or <literal>anycast</literal>.
1464 In other cases, defaults to <literal>global</literal>. The value is
1465 not used for IPv6.</para>
1466 </listitem>
1467 </varlistentry>
1468 <varlistentry>
1469 <term><varname>PreferredSource=</varname></term>
1470 <listitem>
1471 <para>The preferred source address of the route. The address
1472 must be in the format described in
1473 <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
1474 </listitem>
1475 </varlistentry>
1476 <varlistentry>
1477 <term><varname>Table=</varname></term>
1478 <listitem>
1479 <para>The table identifier for the route. Takes one of predefined names <literal>default</literal>, <literal>main</literal>,
1480 and <literal>local</literal>, and names defined in <varname>RouteTable=</varname> in <citerefentry><refentrytitle>networkd.conf</refentrytitle>
1481 <manvolnum>5</manvolnum></citerefentry>, or a number between 1 and 4294967295. The table can be retrieved using
1482 <command>ip route show table <replaceable>num</replaceable></command>. If unset and <varname>Type=</varname> is <literal>local</literal>,
1483 <literal>broadcast</literal>, <literal>anycast</literal>, or <literal>nat</literal>, then <literal>local</literal> is used.
1484 In other cases, defaults to <literal>main</literal>.
1485 </para>
1486 </listitem>
1487 </varlistentry>
1488 <varlistentry>
1489 <term><varname>Protocol=</varname></term>
1490 <listitem>
1491 <para>The protocol identifier for the route. Takes a number between 0 and 255 or the special values
1492 <literal>kernel</literal>, <literal>boot</literal>, <literal>static</literal>,
1493 <literal>ra</literal> and <literal>dhcp</literal>. Defaults to <literal>static</literal>.
1494 </para>
1495 </listitem>
1496 </varlistentry>
1497 <varlistentry>
1498 <term><varname>Type=</varname></term>
1499 <listitem>
1500 <para>Specifies the type for the route. Takes one of <literal>unicast</literal>,
1501 <literal>local</literal>, <literal>broadcast</literal>, <literal>anycast</literal>,
1502 <literal>multicast</literal>, <literal>blackhole</literal>, <literal>unreachable</literal>,
1503 <literal>prohibit</literal>, <literal>throw</literal>, <literal>nat</literal>, and
1504 <literal>xresolve</literal>. If <literal>unicast</literal>, a regular route is defined, i.e. a
1505 route indicating the path to take to a destination network address. If <literal>blackhole</literal>, packets
1506 to the defined route are discarded silently. If <literal>unreachable</literal>, packets to the defined route
1507 are discarded and the ICMP message "Host Unreachable" is generated. If <literal>prohibit</literal>, packets
1508 to the defined route are discarded and the ICMP message "Communication Administratively Prohibited" is
1509 generated. If <literal>throw</literal>, route lookup in the current routing table will fail and the route
1510 selection process will return to Routing Policy Database (RPDB). Defaults to <literal>unicast</literal>.
1511 </para>
1512 </listitem>
1513 </varlistentry>
1514 <varlistentry>
1515 <term><varname>InitialCongestionWindow=</varname></term>
1516 <listitem>
1517 <para>The TCP initial congestion window is used during the start of a TCP connection.
1518 During the start of a TCP session, when a client requests a resource, the server's initial
1519 congestion window determines how many packets will be sent during the initial burst of data
1520 without waiting for acknowledgement. Takes a number between 1 and 1023. Note that 100 is
1521 considered an extremely large value for this option. When unset, the kernel's default
1522 (typically 10) will be used.</para>
1523 </listitem>
1524 </varlistentry>
1525 <varlistentry>
1526 <term><varname>InitialAdvertisedReceiveWindow=</varname></term>
1527 <listitem>
1528 <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
1529 that can initially be buffered at one time on a connection. The sending host can send only
1530 that amount of data before waiting for an acknowledgment and window update from the
1531 receiving host. Takes a number between 1 and 1023. Note that 100 is considered an extremely
1532 large value for this option. When unset, the kernel's default will be used.</para>
1533 </listitem>
1534 </varlistentry>
1535 <varlistentry>
1536 <term><varname>QuickAck=</varname></term>
1537 <listitem>
1538 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1539 </para>
1540 </listitem>
1541 </varlistentry>
1542 <varlistentry>
1543 <term><varname>FastOpenNoCookie=</varname></term>
1544 <listitem>
1545 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1546 When unset, the kernel's default will be used.
1547 </para>
1548 </listitem>
1549 </varlistentry>
1550 <varlistentry>
1551 <term><varname>TTLPropagate=</varname></term>
1552 <listitem>
1553 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1554 When unset, the kernel's default will be used.
1555 </para>
1556 </listitem>
1557 </varlistentry>
1558 <varlistentry>
1559 <term><varname>MTUBytes=</varname></term>
1560 <listitem>
1561 <para>The maximum transmission unit in bytes to set for the
1562 route. The usual suffixes K, M, G, are supported and are
1563 understood to the base of 1024.</para>
1564 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1565 below 1280 (the minimum MTU for IPv6) it will automatically be increased to this value.</para>
1566 </listitem>
1567 </varlistentry>
1568 <varlistentry>
1569 <term><varname>IPServiceType=</varname></term>
1570 <listitem>
1571 <para>Takes string; <literal>CS6</literal> or <literal>CS4</literal>. Used to set IP
1572 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.</para>
1573 </listitem>
1574 </varlistentry>
1575 <varlistentry>
1576 <term><varname>TCPAdvertisedMaximumSegmentSize=</varname></term>
1577 <listitem>
1578 <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G, are
1579 supported and are understood to the base of 1024. An unsigned integer in the range 1–4294967294.
1580 When unset, the kernel's default will be used.</para>
1581 </listitem>
1582 </varlistentry>
1583 <varlistentry>
1584 <term><varname>MultiPathRoute=<replaceable>address</replaceable>[@<replaceable>name</replaceable>] [<replaceable>weight</replaceable>]</varname></term>
1585 <listitem>
1586 <para>Configures multipath route. Multipath routing is the technique of using multiple
1587 alternative paths through a network. Takes gateway address. Optionally, takes a network
1588 interface name or index separated with <literal>@</literal>, and a weight in 1..256 for
1589 this multipath route separated with whitespace. This setting can be specified multiple
1590 times. If an empty string is assigned, then the all previous assignments are cleared.</para>
1591 </listitem>
1592 </varlistentry>
1593 <varlistentry>
1594 <term><varname>NextHop=</varname></term>
1595 <listitem>
1596 <para>Specifies the nexthop id. Takes an unsigned integer in the range 1…4294967295.
1597 If set, the corresponding [NextHop] section must be configured. Defaults to unset.</para>
1598 </listitem>
1599 </varlistentry>
1600 </variablelist>
1601 </refsect1>
1602
1603 <refsect1>
1604 <title>[DHCPv4] Section Options</title>
1605 <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
1606 <varname>DHCP=</varname> setting described above:</para>
1607
1608 <variablelist class='network-directives'>
1609 <varlistentry>
1610 <term><varname>UseDNS=</varname></term>
1611 <listitem>
1612 <para>When true (the default), the DNS servers received from the DHCP server will be used.</para>
1613
1614 <para>This corresponds to the <option>nameserver</option>
1615 option in <citerefentry
1616 project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
1617 </listitem>
1618 </varlistentry>
1619 <varlistentry>
1620 <term><varname>RoutesToDNS=</varname></term>
1621 <listitem>
1622 <para>When true, the routes to the DNS servers received from the DHCP server will be
1623 configured. When <varname>UseDNS=</varname> is disabled, this setting is ignored.
1624 Defaults to false.</para>
1625 </listitem>
1626 </varlistentry>
1627 <varlistentry>
1628 <term><varname>UseNTP=</varname></term>
1629 <listitem>
1630 <para>When true (the default), the NTP servers received from the DHCP server will be used by
1631 <filename>systemd-timesyncd.service</filename>.</para>
1632 </listitem>
1633 </varlistentry>
1634 <varlistentry>
1635 <term><varname>UseSIP=</varname></term>
1636 <listitem>
1637 <para>When true (the default), the SIP servers received from the DHCP server will be collected
1638 and made available to client programs.</para>
1639 </listitem>
1640 </varlistentry>
1641
1642 <varlistentry>
1643 <term><varname>UseMTU=</varname></term>
1644 <listitem>
1645 <para>When true, the interface maximum transmission unit
1646 from the DHCP server will be used on the current link.
1647 If <varname>MTUBytes=</varname> is set, then this setting is ignored.
1648 Defaults to false.</para>
1649 </listitem>
1650 </varlistentry>
1651 <varlistentry>
1652 <term><varname>Anonymize=</varname></term>
1653 <listitem>
1654 <para>Takes a boolean. When true, the options sent to the DHCP server will follow the
1655 <ulink url="https://tools.ietf.org/html/rfc7844">RFC 7844</ulink> (Anonymity Profiles for
1656 DHCP Clients) to minimize disclosure of identifying information. Defaults to false.</para>
1657
1658 <para>This option should only be set to true when <varname>MACAddressPolicy=</varname> is
1659 set to <literal>random</literal> (see
1660 <citerefentry project='man-pages'><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
1661 </para>
1662
1663 <para>When true, <varname>SendHostname=</varname>, <varname>ClientIdentifier=</varname>,
1664 <varname>VendorClassIdentifier=</varname>, <varname>UserClass=</varname>,
1665 <varname>RequestOptions=</varname>, <varname>SendOption=</varname>,
1666 <varname>SendVendorOption=</varname>, and <varname>MUDURL=</varname> are ignored.</para>
1667
1668 <para>With this option enabled DHCP requests will mimic those generated by Microsoft
1669 Windows, in order to reduce the ability to fingerprint and recognize installations. This
1670 means DHCP request sizes will grow and lease data will be more comprehensive than normally,
1671 though most of the requested data is not actually used.</para>
1672 </listitem>
1673 </varlistentry>
1674 <varlistentry>
1675 <term><varname>SendHostname=</varname></term>
1676 <listitem>
1677 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1678 Note that the machine's hostname must consist only of 7-bit ASCII lower-case characters and
1679 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1680 sent even if this is set to true.</para>
1681 </listitem>
1682 </varlistentry>
1683
1684 <varlistentry>
1685 <term><varname>MUDURL=</varname></term>
1686 <listitem>
1687 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent to the
1688 DHCPv4 server. Takes a URL of length up to 255 characters. A superficial verification that the
1689 string is a valid URL will be performed. DHCPv4 clients are intended to have at most one MUD URL
1690 associated with them. See <ulink url="https://tools.ietf.org/html/rfc8520">RFC 8520</ulink>.
1691 </para>
1692
1693 <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers to
1694 advertise device specifications, including the intended communication patterns for their device
1695 when it connects to the network. The network can then use this to author a context-specific
1696 access policy, so the device functions only within those parameters.</para>
1697 </listitem>
1698 </varlistentry>
1699
1700 <varlistentry>
1701 <term><varname>UseHostname=</varname></term>
1702 <listitem>
1703 <para>When true (the default), the hostname received from
1704 the DHCP server will be set as the transient hostname of the system.
1705 </para>
1706 </listitem>
1707 </varlistentry>
1708 <varlistentry>
1709 <term><varname>Hostname=</varname></term>
1710 <listitem>
1711 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1712 Note that the specified hostname must consist only of 7-bit ASCII lower-case characters and
1713 no spaces or dots, and be formatted as a valid DNS domain name.</para>
1714 </listitem>
1715 </varlistentry>
1716 <varlistentry>
1717 <term><varname>UseDomains=</varname></term>
1718 <listitem>
1719 <para>Takes a boolean, or the special value <literal>route</literal>. When true, the domain name
1720 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1721 the <option>Domains=</option> setting. If set to <literal>route</literal>, the domain name received from
1722 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1723 the <option>Domains=</option> setting when the argument is prefixed with <literal>~</literal>. Defaults to
1724 false.</para>
1725
1726 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1727 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
1728 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1729 single-label names.</para>
1730
1731 <para>When set to true, this setting corresponds to the <option>domain</option> option in <citerefentry
1732 project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
1733 </listitem>
1734 </varlistentry>
1735 <varlistentry>
1736 <term><varname>UseRoutes=</varname></term>
1737 <listitem>
1738 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1739 routing table with a metric of 1024, and a scope of "global", "link" or "host", depending on the route's
1740 destination and gateway. If the destination is on the local host, e.g., 127.x.x.x, or the same as the
1741 link's own address, the scope will be set to "host". Otherwise if the gateway is null (a direct route), a
1742 "link" scope will be used. For anything else, scope defaults to "global".</para>
1743 </listitem>
1744 </varlistentry>
1745 <varlistentry>
1746 <term><varname>UseGateway=</varname></term>
1747 <listitem>
1748 <para>When true, the gateway will be requested from the DHCP server and added to the routing table with a
1749 metric of 1024, and a scope of "link". When unset, the value specified with <option>UseRoutes=</option>
1750 is used.</para>
1751 </listitem>
1752 </varlistentry>
1753 <varlistentry>
1754 <term><varname>UseTimezone=</varname></term>
1755 <listitem><para>When true, the timezone received from the
1756 DHCP server will be set as timezone of the local
1757 system. Defaults to <literal>no</literal>.</para></listitem>
1758 </varlistentry>
1759
1760 <varlistentry>
1761 <term><varname>ClientIdentifier=</varname></term>
1762 <listitem>
1763 <para>The DHCPv4 client identifier to use. Takes one of <literal>mac</literal>, <literal>duid</literal> or <literal>duid-only</literal>.
1764 If set to <literal>mac</literal>, the MAC address of the link is used.
1765 If set to <literal>duid</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1766 If set to <literal>duid-only</literal>, only DUID is used, this may not be RFC compliant, but some setups may require to use this.
1767 Defaults to <literal>duid</literal>.</para>
1768 </listitem>
1769 </varlistentry>
1770
1771 <varlistentry>
1772 <term><varname>VendorClassIdentifier=</varname></term>
1773 <listitem>
1774 <para>The vendor class identifier used to identify vendor
1775 type and configuration.</para>
1776 </listitem>
1777 </varlistentry>
1778
1779 <varlistentry>
1780 <term><varname>UserClass=</varname></term>
1781 <listitem>
1782 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1783 it represents. The information contained in this option is a string that represents the user class of which
1784 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1785 service to classify clients. Takes a whitespace-separated list of strings.</para>
1786 </listitem>
1787 </varlistentry>
1788
1789 <varlistentry>
1790 <term><varname>MaxAttempts=</varname></term>
1791 <listitem>
1792 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1793 number or <literal>infinity</literal>. Defaults to <literal>infinity</literal>. Note that the
1794 time between retries is increased exponentially, up to approximately one per minute, so the
1795 network will not be overloaded even if this number is high. The default is suitable in most
1796 circumstances.</para>
1797 </listitem>
1798 </varlistentry>
1799
1800 <varlistentry>
1801 <term><varname>DUIDType=</varname></term>
1802 <listitem>
1803 <para>Override the global <varname>DUIDType</varname> setting for this network. See
1804 <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1805 for a description of possible values.</para>
1806 </listitem>
1807 </varlistentry>
1808
1809 <varlistentry>
1810 <term><varname>DUIDRawData=</varname></term>
1811 <listitem>
1812 <para>Override the global <varname>DUIDRawData</varname> setting for this network. See
1813 <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1814 for a description of possible values.</para>
1815 </listitem>
1816 </varlistentry>
1817
1818 <varlistentry>
1819 <term><varname>IAID=</varname></term>
1820 <listitem>
1821 <para>The DHCP Identity Association Identifier (IAID) for the interface, a 32-bit unsigned integer.</para>
1822 </listitem>
1823 </varlistentry>
1824
1825 <varlistentry>
1826 <term><varname>RequestBroadcast=</varname></term>
1827 <listitem>
1828 <para>Request the server to use broadcast messages before
1829 the IP address has been configured. This is necessary for
1830 devices that cannot receive RAW packets, or that cannot
1831 receive packets at all before an IP address has been
1832 configured. On the other hand, this must not be enabled on
1833 networks where broadcasts are filtered out.</para>
1834 </listitem>
1835 </varlistentry>
1836
1837 <varlistentry>
1838 <term><varname>RouteMetric=</varname></term>
1839 <listitem>
1840 <para>Set the routing metric for routes specified by the DHCP server. Defaults to 1024.</para>
1841 </listitem>
1842 </varlistentry>
1843
1844 <varlistentry>
1845 <term><varname>RouteTable=<replaceable>num</replaceable></varname></term>
1846 <listitem>
1847 <para>The table identifier for DHCP routes (a number between 1 and 4294967295, or 0 to unset).
1848 The table can be retrieved using <command>ip route show table <replaceable>num</replaceable></command>.
1849 </para>
1850 <para>When used in combination with <varname>VRF=</varname>, the
1851 VRF's routing table is used when this parameter is not specified.
1852 </para>
1853 </listitem>
1854 </varlistentry>
1855
1856 <varlistentry>
1857 <term><varname>RouteMTUBytes=</varname></term>
1858 <listitem>
1859 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.</para>
1860 </listitem>
1861 </varlistentry>
1862
1863 <varlistentry>
1864 <term><varname>ListenPort=</varname></term>
1865 <listitem>
1866 <para>Allow setting custom port for the DHCP client to listen on.</para>
1867 </listitem>
1868 </varlistentry>
1869
1870 <varlistentry>
1871 <term><varname>FallbackLeaseLifetimeSec=</varname></term>
1872 <listitem>
1873 <para>Allows to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease lifetime.
1874 Takes one of <literal>forever</literal> or <literal>infinity</literal> means that the address
1875 never expires. Defaults to unset.</para>
1876 </listitem>
1877 </varlistentry>
1878
1879 <varlistentry>
1880 <term><varname>SendRelease=</varname></term>
1881 <listitem>
1882 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops.
1883 Defaults to true.</para>
1884 </listitem>
1885 </varlistentry>
1886
1887 <varlistentry>
1888 <term><varname>SendDecline=</varname></term>
1889 <listitem>
1890 <para>A boolean. When <literal>true</literal>, the DHCPv4 client receives the IP address from the
1891 DHCP server. After a new IP is received, the DHCPv4 client performs IPv4 Duplicate Address
1892 Detection. If duplicate use is detected, the DHCPv4 client rejects the IP by sending a
1893 DHCPDECLINE packet and tries to obtain an IP address again. See <ulink
1894 url="https://tools.ietf.org/html/rfc5227">RFC 5224</ulink>. Defaults to
1895 <literal>unset</literal>.</para>
1896 </listitem>
1897 </varlistentry>
1898
1899 <varlistentry>
1900 <term><varname>DenyList=</varname></term>
1901 <listitem>
1902 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are rejected. Note that
1903 if <varname>AllowList=</varname> is configured then <varname>DenyList=</varname> is ignored.</para>
1904 </listitem>
1905 </varlistentry>
1906
1907 <varlistentry>
1908 <term><varname>AllowList=</varname></term>
1909 <listitem>
1910 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are accepted.</para>
1911 </listitem>
1912 </varlistentry>
1913
1914 <varlistentry>
1915 <term><varname>RequestOptions=</varname></term>
1916 <listitem>
1917 <para>Sets request options to be sent to the server in the DHCPv4 request options list. A
1918 whitespace-separated list of integers in the range 1…254. Defaults to unset.</para>
1919 </listitem>
1920 </varlistentry>
1921
1922 <varlistentry>
1923 <term><varname>SendOption=</varname></term>
1924 <listitem>
1925 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data type
1926 and data separated with a colon
1927 (<literal><replaceable>option</replaceable>:<replaceable>type</replaceable>:<replaceable>value</replaceable></literal>).
1928 The option number must be an integer in the range 1…254. The type takes one of
1929 <literal>uint8</literal>, <literal>uint16</literal>, <literal>uint32</literal>,
1930 <literal>ipv4address</literal>, or <literal>string</literal>. Special characters in the data
1931 string may be escaped using <ulink
1932 url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1933 escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
1934 then all options specified earlier are cleared. Defaults to unset.</para>
1935 </listitem>
1936 </varlistentry>
1937
1938 <varlistentry>
1939 <term><varname>SendVendorOption=</varname></term>
1940 <listitem>
1941 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data
1942 type and data separated with a colon
1943 (<literal><replaceable>option</replaceable>:<replaceable>type</replaceable>:<replaceable>value</replaceable></literal>).
1944 The option number must be an integer in the range 1…254. The type takes one of
1945 <literal>uint8</literal>, <literal>uint16</literal>, <literal>uint32</literal>,
1946 <literal>ipv4address</literal>, or <literal>string</literal>. Special characters in the data
1947 string may be escaped using <ulink
1948 url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1949 escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
1950 then all options specified earlier are cleared. Defaults to unset.</para>
1951 </listitem>
1952 </varlistentry>
1953 </variablelist>
1954 </refsect1>
1955
1956 <refsect1>
1957 <title>[DHCPv6] Section Options</title>
1958 <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
1959 <varname>DHCP=</varname> setting described above, or invoked by the IPv6 Router Advertisement:</para>
1960
1961 <variablelist class='network-directives'>
1962 <varlistentry>
1963 <term><varname>UseAddress=</varname></term>
1964 <listitem>
1965 <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
1966 assigned.</para>
1967 </listitem>
1968 </varlistentry>
1969
1970 <varlistentry>
1971 <term><varname>UseDNS=</varname></term>
1972 <term><varname>UseNTP=</varname></term>
1973 <term><varname>UseHostname=</varname></term>
1974 <term><varname>UseDomains=</varname></term>
1975 <listitem>
1976 <para>As in the [DHCPv4] section.</para>
1977 </listitem>
1978 </varlistentry>
1979
1980 <varlistentry>
1981 <term><varname>RouteMetric=</varname></term>
1982 <listitem>
1983 <para>Set the routing metric for routes specified by the DHCP server. Defaults to 1024.</para>
1984 </listitem>
1985 </varlistentry>
1986
1987 <varlistentry>
1988 <term><varname>RapidCommit=</varname></term>
1989 <listitem>
1990 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1991 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1992 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1993 four-message exchange (solicit, advertise, request, and reply). The two-message exchange provides
1994 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1995 See <ulink url="https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC 3315</ulink> for details.
1996 Defaults to true.</para>
1997 </listitem>
1998 </varlistentry>
1999
2000 <varlistentry>
2001 <term><varname>MUDURL=</varname></term>
2002 <listitem>
2003 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent to
2004 the DHCPv6 server. The syntax and semantics are the same as for <varname>MUDURL=</varname> in the
2005 [DHCPv4] section described above.</para>
2006 </listitem>
2007 </varlistentry>
2008
2009 <varlistentry>
2010 <term><varname>RequestOptions=</varname></term>
2011 <listitem>
2012 <para>When configured, allows to set arbitrary request options in the DHCPv6 request options list
2013 that will be sent to the DHCPv6 server. A whitespace-separated list of integers in the range
2014 1…254. Defaults to unset.</para>
2015 </listitem>
2016 </varlistentry>
2017
2018 <varlistentry>
2019 <term><varname>SendVendorOption=</varname></term>
2020 <listitem>
2021 <para>Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier, DHCP
2022 option number, data type, and data separated with a colon (<literal><replaceable>enterprise
2023 identifier</replaceable>:<replaceable>option</replaceable>:<replaceable>type</replaceable>:
2024 <replaceable>value</replaceable></literal>). Enterprise identifier is an unsigned integer in the
2025 range 1–4294967294. The option number must be an integer in the range 1–254. Data type takes one
2026 of <literal>uint8</literal>, <literal>uint16</literal>, <literal>uint32</literal>,
2027 <literal>ipv4address</literal>, <literal>ipv6address</literal>, or
2028 <literal>string</literal>. Special characters in the data string may be escaped using <ulink
2029 url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2030 escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
2031 then all options specified earlier are cleared. Defaults to unset.</para>
2032 </listitem>
2033 </varlistentry>
2034
2035 <varlistentry>
2036 <term><varname>ForceDHCPv6PDOtherInformation=</varname></term>
2037 <listitem>
2038 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
2039 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
2040 makes DHCPv6 request network information in a stateless manner using a two-message Information
2041 Request and Information Reply message exchange.
2042 <ulink url="https://tools.ietf.org/html/rfc7084">RFC 7084</ulink>, requirement WPD-4, updates
2043 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
2044 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
2045 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
2046 By default this option is set to 'false', enable it if no prefixes are delegated when the device
2047 should be acting as a CE router.</para>
2048 </listitem>
2049 </varlistentry>
2050
2051 <varlistentry>
2052 <term><varname>PrefixDelegationHint=</varname></term>
2053 <listitem>
2054 <para>Takes an IPv6 address with prefix length in the same format as the
2055 <varname>Address=</varname> in the [Network] section. The DHCPv6 client will include a prefix
2056 hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
2057 1–128. Defaults to unset.</para>
2058 </listitem>
2059 </varlistentry>
2060
2061 <varlistentry>
2062 <term><varname>WithoutRA=</varname></term>
2063 <listitem>
2064 <para>Allows DHCPv6 client to start without router advertisements's managed or other address
2065 configuration flag. Takes one of <literal>solicit</literal> or
2066 <literal>information-request</literal>. Defaults to unset.</para>
2067 </listitem>
2068 </varlistentry>
2069
2070 <varlistentry>
2071 <term><varname>SendOption=</varname></term>
2072 <listitem>
2073 <para>As in the [DHCPv4] section, however because DHCPv6 uses 16-bit fields to store
2074 option numbers, the option number is an integer in the range 1…65536.</para>
2075 </listitem>
2076 </varlistentry>
2077
2078 <varlistentry>
2079 <term><varname>UserClass=</varname></term>
2080 <listitem>
2081 <para>A DHCPv6 client can use User Class option to identify the type or category of user or applications
2082 it represents. The information contained in this option is a string that represents the user class of which
2083 the client is a member. Each class sets an identifying string of information to be used by the DHCP
2084 service to classify clients. Special characters in the data string may be escaped using
2085 <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2086 escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
2087 then all options specified earlier are cleared. Takes a whitespace-separated list of strings. Note that
2088 currently <constant>NUL</constant> bytes are not allowed.</para>
2089 </listitem>
2090 </varlistentry>
2091
2092 <varlistentry>
2093 <term><varname>VendorClass=</varname></term>
2094 <listitem>
2095 <para>A DHCPv6 client can use VendorClass option to identify the vendor that
2096 manufactured the hardware on which the client is running. The information
2097 contained in the data area of this option is contained in one or more opaque
2098 fields that identify details of the hardware configuration. Takes a
2099 whitespace-separated list of strings.</para>
2100 </listitem>
2101 </varlistentry>
2102 </variablelist>
2103 </refsect1>
2104
2105 <refsect1>
2106 <title>[DHCPv6PrefixDelegation] Section Options</title>
2107 <para>The [DHCPv6PrefixDelegation] section configures delegated prefixes assigned by DHCPv6 server.
2108 The settings in this section are used only when <varname>DHCPv6PrefixDelegation=</varname> setting
2109 is enabled.</para>
2110
2111 <variablelist class='network-directives'>
2112 <varlistentry>
2113 <term><varname>SubnetId=</varname></term>
2114 <listitem>
2115 <para>Configure a specific subnet ID on the interface from a (previously) received prefix
2116 delegation. You can either set "auto" (the default) or a specific subnet ID (as defined in
2117 <ulink url="https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC 4291</ulink>, section
2118 2.5.4), in which case the allowed value is hexadecimal, from 0 to 0x7fffffffffffffff
2119 inclusive.</para>
2120 </listitem>
2121 </varlistentry>
2122
2123 <varlistentry>
2124 <term><varname>Announce=</varname></term>
2125 <listitem>
2126 <para>Takes a boolean. When enabled, and <varname>IPv6SendRA=</varname> in [Network] section
2127 is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
2128 Defaults to yes.</para>
2129 </listitem>
2130 </varlistentry>
2131
2132 <varlistentry>
2133 <term><varname>Assign=</varname></term>
2134 <listitem>
2135 <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
2136 are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
2137 interfce), the EUI-64 algorithm will be used by default to form an interface identifier from
2138 the delegated prefixes. See also <varname>Token=</varname> setting below. Defaults to yes.
2139 </para>
2140 </listitem>
2141 </varlistentry>
2142
2143 <varlistentry>
2144 <term><varname>Token=</varname></term>
2145 <listitem>
2146 <para>Specifies an optional address generation mode for assigning an address in each
2147 delegated prefix. Takes an IPv6 address. When set, the lower bits of the supplied address is
2148 combined with the upper bits of each delegatad prefix received from the WAN interface by the
2149 DHCPv6 Prefix Delegation to form a complete address. When <varname>Assign=</varname> is
2150 disabled, this setting is ignored. When unset, the EUI-64 algorithm will be used to form
2151 addresses. Defaults to unset.</para>
2152 </listitem>
2153 </varlistentry>
2154
2155 <varlistentry>
2156 <term><varname>ManageTemporaryAddress=</varname></term>
2157 <listitem>
2158 <para>As in the [Address] section, but defaults to true.</para>
2159 </listitem>
2160 </varlistentry>
2161 </variablelist>
2162 </refsect1>
2163
2164 <refsect1>
2165 <title>[IPv6AcceptRA] Section Options</title>
2166 <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
2167 with the <varname>IPv6AcceptRA=</varname> setting described above:</para>
2168
2169 <variablelist class='network-directives'>
2170 <varlistentry>
2171 <term><varname>UseDNS=</varname></term>
2172 <listitem>
2173 <para>When true (the default), the DNS servers received in the Router Advertisement will be used.</para>
2174
2175 <para>This corresponds to the <option>nameserver</option> option in <citerefentry
2176 project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
2177 </listitem>
2178 </varlistentry>
2179
2180 <varlistentry>
2181 <term><varname>UseDomains=</varname></term>
2182 <listitem>
2183 <para>Takes a boolean, or the special value <literal>route</literal>. When true, the domain name
2184 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
2185 the effect of the <option>Domains=</option> setting. If set to <literal>route</literal>, the domain name
2186 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
2187 effect of the <option>Domains=</option> setting when the argument is prefixed with
2188 <literal>~</literal>. Defaults to false.</para>
2189
2190 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
2191 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
2192 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
2193 single-label names.</para>
2194
2195 <para>When set to true, this setting corresponds to the <option>domain</option> option in <citerefentry
2196 project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
2197 </listitem>
2198 </varlistentry>
2199
2200 <varlistentry>
2201 <term><varname>RouteTable=<replaceable>num</replaceable></varname></term>
2202 <listitem>
2203 <para>The table identifier for the routes received in the Router Advertisement
2204 (a number between 1 and 4294967295, or 0 to unset).
2205 The table can be retrieved using <command>ip route show table <replaceable>num</replaceable></command>.
2206 </para>
2207 </listitem>
2208 </varlistentry>
2209
2210 <varlistentry>
2211 <term><varname>UseAutonomousPrefix=</varname></term>
2212 <listitem>
2213 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
2214 precedence over any statically configured ones.</para>
2215 </listitem>
2216 </varlistentry>
2217
2218 <varlistentry>
2219 <term><varname>UseOnLinkPrefix=</varname></term>
2220 <listitem>
2221 <para>When true (the default), the onlink prefix received in the Router Advertisement will be
2222 used and takes precedence over any statically configured ones.</para>
2223 </listitem>
2224 </varlistentry>
2225
2226 <varlistentry>
2227 <term><varname>RouterDenyList=</varname></term>
2228 <listitem>
2229 <para>A whitespace-separated list of IPv6 router addresses. Any information advertised by
2230 the listed router is ignored.</para>
2231 </listitem>
2232 </varlistentry>
2233
2234 <varlistentry>
2235 <term><varname>RouterAllowList=</varname></term>
2236 <listitem>
2237 <para>A whitespace-separated list of IPv6 router addresses. Only information advertised by
2238 the listed router is accepted. Note that if <varname>RouterAllowList=</varname> is
2239 configured then <varname>RouterDenyList=</varname> is ignored.</para>
2240 </listitem>
2241 </varlistentry>
2242
2243 <varlistentry>
2244 <term><varname>PrefixDenyList=</varname></term>
2245 <listitem>
2246 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router
2247 advertisements in the list are ignored.</para>
2248 </listitem>
2249 </varlistentry>
2250
2251 <varlistentry>
2252 <term><varname>PrefixAllowList=</varname></term>
2253 <listitem>
2254 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router
2255 advertisements in the list are allowed. Note that if <varname>PrefixAllowList=</varname> is
2256 configured then <varname>PrefixDenyList=</varname> is ignored.</para>
2257 </listitem>
2258 </varlistentry>
2259
2260 <varlistentry>
2261 <term><varname>RouteDenyList=</varname></term>
2262 <listitem>
2263 <para>A whitespace-separated list of IPv6 route prefixes. IPv6 route prefixes supplied via
2264 router advertisements in the list are ignored.</para>
2265 </listitem>
2266 </varlistentry>
2267
2268 <varlistentry>
2269 <term><varname>RouteAllowList=</varname></term>
2270 <listitem>
2271 <para>A whitespace-separated list of IPv6 route prefixes. IPv6 route prefixes supplied via
2272 router advertisements in the list are allowed. Note that if <varname>RouteAllowList=</varname> is
2273 configured then <varname>RouteDenyList=</varname> is ignored.</para>
2274 </listitem>
2275 </varlistentry>
2276
2277 <varlistentry>
2278 <term><varname>DHCPv6Client=</varname></term>
2279 <listitem>
2280 <para>Takes a boolean, or the special value <literal>always</literal>. When true or
2281 <literal>always</literal>, the DHCPv6 client will be started when the RA has the managed or
2282 other information flag. If set to <literal>always</literal>, the DHCPv6 client will also be
2283 started in managed mode when neither managed nor other information flag is set in the RA.
2284 Defaults to true.</para>
2285 </listitem>
2286 </varlistentry>
2287 </variablelist>
2288 </refsect1>
2289
2290 <refsect1>
2291 <title>[DHCPServer] Section Options</title>
2292 <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
2293 <varname>DHCPServer=</varname> option described above:</para>
2294
2295 <variablelist class='network-directives'>
2296
2297 <varlistentry>
2298 <term><varname>RelayTarget=</varname></term>
2299 <listitem>
2300 <para>Takes an IPv4 address, which must be in the format
2301 described in
2302 <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
2303 Turns this DHCP server into a DHCP relay agent. See <ulink url="https://tools.ietf.org/html/rfc1542">RFC 1542</ulink>.
2304 The address is the address of DHCP server or another relay agent to forward DHCP messages to and from.</para>
2305 Check also BindToInterface= option. Turning it off is required for relaying messages outside.
2306 </listitem>
2307 </varlistentry>
2308 <varlistentry>
2309 <term><varname>PoolOffset=</varname></term>
2310 <term><varname>PoolSize=</varname></term>
2311
2312 <listitem><para>Configures the pool of addresses to hand out. The pool
2313 is a contiguous sequence of IP addresses in the subnet configured for
2314 the server address, which does not include the subnet nor the broadcast
2315 address. <varname>PoolOffset=</varname> takes the offset of the pool
2316 from the start of subnet, or zero to use the default value.
2317 <varname>PoolSize=</varname> takes the number of IP addresses in the
2318 pool or zero to use the default value. By default, the pool starts at
2319 the first address after the subnet address and takes up the rest of
2320 the subnet, excluding the broadcast address. If the pool includes
2321 the server address (the default), this is reserved and not handed
2322 out to clients.</para></listitem>
2323 </varlistentry>
2324
2325 <varlistentry>
2326 <term><varname>DefaultLeaseTimeSec=</varname></term>
2327 <term><varname>MaxLeaseTimeSec=</varname></term>
2328
2329 <listitem><para>Control the default and maximum DHCP lease
2330 time to pass to clients. These settings take time values in seconds or
2331 another common time unit, depending on the suffix. The default
2332 lease time is used for clients that did not ask for a specific
2333 lease time. If a client asks for a lease time longer than the
2334 maximum lease time, it is automatically shortened to the
2335 specified time. The default lease time defaults to 1h, the
2336 maximum lease time to 12h. Shorter lease times are beneficial
2337 if the configuration data in DHCP leases changes frequently
2338 and clients shall learn the new settings with shorter
2339 latencies. Longer lease times reduce the generated DHCP
2340 network traffic.</para></listitem>
2341 </varlistentry>
2342
2343 <varlistentry>
2344 <term><varname>EmitDNS=</varname></term>
2345 <term><varname>DNS=</varname></term>
2346
2347 <listitem><para><varname>EmitDNS=</varname> takes a boolean. Configures whether the DHCP leases
2348 handed out to clients shall contain DNS server information. Defaults to <literal>yes</literal>. The
2349 DNS servers to pass to clients may be configured with the <varname>DNS=</varname> option, which takes
2350 a list of IPv4 addresses. If the <varname>EmitDNS=</varname> option is enabled but no servers
2351 configured, the servers are automatically propagated from an "uplink" interface that has appropriate
2352 servers set. The "uplink" interface is determined by the default route of the system with the highest
2353 priority. Note that this information is acquired at the time the lease is handed out, and does not
2354 take uplink interfaces into account that acquire DNS server information at a later point. If no
2355 suitable uplink interface is found the DNS server data from <filename>/etc/resolv.conf</filename> is
2356 used. Also, note that the leases are not refreshed if the uplink network configuration changes. To
2357 ensure clients regularly acquire the most current uplink DNS server information, it is thus advisable
2358 to shorten the DHCP lease time via <varname>MaxLeaseTimeSec=</varname> described
2359 above.</para></listitem>
2360 </varlistentry>
2361
2362 <varlistentry>
2363 <term><varname>EmitNTP=</varname></term>
2364 <term><varname>NTP=</varname></term>
2365 <term><varname>EmitSIP=</varname></term>
2366 <term><varname>SIP=</varname></term>
2367 <term><varname>EmitPOP3=</varname></term>
2368 <term><varname>POP3=</varname></term>
2369 <term><varname>EmitSMTP=</varname></term>
2370 <term><varname>SMTP=</varname></term>
2371 <term><varname>EmitLPR=</varname></term>
2372 <term><varname>LPR=</varname></term>
2373
2374 <listitem><para>Similar to the <varname>EmitDNS=</varname> and <varname>DNS=</varname> settings
2375 described above, these settings configure whether and what server information for the indicate
2376 protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
2377 defaults apply as for <varname>EmitDNS=</varname> and <varname>DNS=</varname>.</para></listitem>
2378 </varlistentry>
2379
2380 <varlistentry>
2381 <term><varname>EmitRouter=</varname></term>
2382
2383 <listitem><para>Similar to the <varname>EmitDNS=</varname>
2384 setting described above, this setting configures whether the
2385 DHCP lease should contain the router option. The same syntax,
2386 propagation semantics and defaults apply as for
2387 <varname>EmitDNS=</varname>.</para></listitem>
2388 </varlistentry>
2389
2390 <varlistentry>
2391 <term><varname>EmitTimezone=</varname></term>
2392 <term><varname>Timezone=</varname></term>
2393
2394 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
2395 to clients shall contain timezone information. Defaults to <literal>yes</literal>. The
2396 <varname>Timezone=</varname> setting takes a timezone string
2397 (such as <literal>Europe/Berlin</literal> or
2398 <literal>UTC</literal>) to pass to clients. If no explicit
2399 timezone is set, the system timezone of the local host is
2400 propagated, as determined by the
2401 <filename>/etc/localtime</filename> symlink.</para></listitem>
2402 </varlistentry>
2403
2404 <varlistentry>
2405 <term><varname>SendOption=</varname></term>
2406 <listitem>
2407 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
2408 and data (<literal><replaceable>option</replaceable>:<replaceable>type</replaceable>:<replaceable>value</replaceable></literal>).
2409 The option number is an integer in the range 1…254. The type takes one of <literal>uint8</literal>,
2410 <literal>uint16</literal>, <literal>uint32</literal>, <literal>ipv4address</literal>, <literal>ipv6address</literal>, or
2411 <literal>string</literal>. Special characters in the data string may be escaped using
2412 <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2413 escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
2414 then all options specified earlier are cleared. Defaults to unset.</para>
2415 </listitem>
2416 </varlistentry>
2417
2418 <varlistentry>
2419 <term><varname>SendVendorOption=</varname></term>
2420 <listitem>
2421 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
2422 and data (<literal><replaceable>option</replaceable>:<replaceable>type</replaceable>:<replaceable>value</replaceable></literal>).
2423 The option number is an integer in the range 1…254. The type takes one of <literal>uint8</literal>,
2424 <literal>uint16</literal>, <literal>uint32</literal>, <literal>ipv4address</literal>, or
2425 <literal>string</literal>. Special characters in the data string may be escaped using
2426 <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2427 escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
2428 then all options specified earlier are cleared. Defaults to unset.</para>
2429 </listitem>
2430 </varlistentry>
2431 <varlistentry>
2432 <term><varname>BindToInterface=</varname></term>
2433 <listitem>Takes a boolean value. When <literal>yes</literal>, DHCP server socket will be bound
2434 to its network interface and all socket communication will be restricted to this interface.
2435 Defaults to <literal>yes</literal>.
2436 </listitem>
2437 </varlistentry>
2438
2439 </variablelist>
2440 </refsect1>
2441
2442 <refsect1>
2443 <title>[IPv6SendRA] Section Options</title>
2444 <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
2445 to act as a router, if enabled via the <varname>IPv6SendRA=</varname> option described above. IPv6
2446 network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
2447 </para>
2448
2449 <variablelist class='network-directives'>
2450
2451 <varlistentry>
2452 <term><varname>Managed=</varname></term>
2453 <term><varname>OtherInformation=</varname></term>
2454
2455 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
2456 addresses on the network link when <varname>Managed=</varname>
2457 is set to <literal>true</literal> or if only additional network
2458 information can be obtained via DHCPv6 for the network link when
2459 <varname>OtherInformation=</varname> is set to
2460 <literal>true</literal>. Both settings default to
2461 <literal>false</literal>, which means that a DHCPv6 server is not being
2462 used.</para></listitem>
2463 </varlistentry>
2464
2465 <varlistentry>
2466 <term><varname>RouterLifetimeSec=</varname></term>
2467
2468 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. When set to
2469 0, the host is not acting as a router. Defaults to 30 minutes.</para>
2470 </listitem>
2471 </varlistentry>
2472
2473 <varlistentry>
2474 <term><varname>RouterPreference=</varname></term>
2475
2476 <listitem><para>Configures IPv6 router preference if
2477 <varname>RouterLifetimeSec=</varname> is non-zero. Valid values are
2478 <literal>high</literal>, <literal>medium</literal> and
2479 <literal>low</literal>, with <literal>normal</literal> and
2480 <literal>default</literal> added as synonyms for
2481 <literal>medium</literal> just to make configuration easier. See
2482 <ulink url="https://tools.ietf.org/html/rfc4191">RFC 4191</ulink>
2483 for details. Defaults to <literal>medium</literal>.</para></listitem>
2484 </varlistentry>
2485
2486 <varlistentry>
2487 <term><varname>EmitDNS=</varname></term>
2488 <term><varname>DNS=</varname></term>
2489
2490 <listitem><para><varname>DNS=</varname> specifies a list of recursive DNS server IPv6 addresses that
2491 are distributed via Router Advertisement messages when <varname>EmitDNS=</varname> is
2492 true. <varname>DNS=</varname> also takes special value <literal>_link_local</literal>; in that case
2493 the IPv6 link local address is distributed. If <varname>DNS=</varname> is empty, DNS servers are read
2494 from the [Network] section. If the [Network] section does not contain any DNS servers either, DNS
2495 servers from the uplink with the highest priority default route are used. When
2496 <varname>EmitDNS=</varname> is false, no DNS server information is sent in Router Advertisement
2497 messages. <varname>EmitDNS=</varname> defaults to true.</para></listitem>
2498 </varlistentry>
2499
2500 <varlistentry>
2501 <term><varname>EmitDomains=</varname></term>
2502 <term><varname>Domains=</varname></term>
2503
2504 <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
2505 <varname>EmitDomains=</varname> is true. If <varname>Domains=</varname> is empty, DNS search domains
2506 are read from the [Network] section. If the [Network] section does not contain any DNS search domains
2507 either, DNS search domains from the uplink with the highest priority default route are used. When
2508 <varname>EmitDomains=</varname> is false, no DNS search domain information is sent in Router
2509 Advertisement messages. <varname>EmitDomains=</varname> defaults to true.</para></listitem>
2510 </varlistentry>
2511
2512 <varlistentry>
2513 <term><varname>DNSLifetimeSec=</varname></term>
2514
2515 <listitem><para>Lifetime in seconds for the DNS server addresses listed
2516 in <varname>DNS=</varname> and search domains listed in
2517 <varname>Domains=</varname>.</para></listitem>
2518 </varlistentry>
2519
2520 </variablelist>
2521 </refsect1>
2522
2523 <refsect1>
2524 <title>[IPv6Prefix] Section Options</title>
2525 <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
2526 Advertisements. See <ulink url="https://tools.ietf.org/html/rfc4861">RFC 4861</ulink> for further
2527 details.</para>
2528
2529 <variablelist class='network-directives'>
2530
2531 <varlistentry>
2532 <term><varname>AddressAutoconfiguration=</varname></term>
2533 <term><varname>OnLink=</varname></term>
2534
2535 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
2536 autoconfigured with this prefix and whether the prefix can be used for
2537 onlink determination. Both settings default to <literal>true</literal>
2538 in order to ease configuration.
2539 </para></listitem>
2540 </varlistentry>
2541
2542 <varlistentry>
2543 <term><varname>Prefix=</varname></term>
2544
2545 <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
2546 IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
2547 <literal>/</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
2548 prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
2549 prefix to another.</para></listitem>
2550 </varlistentry>
2551
2552 <varlistentry>
2553 <term><varname>PreferredLifetimeSec=</varname></term>
2554 <term><varname>ValidLifetimeSec=</varname></term>
2555
2556 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2557 seconds. <varname>PreferredLifetimeSec=</varname> defaults to 604800
2558 seconds (one week) and <varname>ValidLifetimeSec=</varname> defaults
2559 to 2592000 seconds (30 days).</para></listitem>
2560 </varlistentry>
2561
2562 <varlistentry>
2563 <term><varname>Assign=</varname></term>
2564 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
2565 </para></listitem>
2566 </varlistentry>
2567 </variablelist>
2568 </refsect1>
2569
2570 <refsect1>
2571 <title>[IPv6RoutePrefix] Section Options</title>
2572 <para>One or more [IPv6RoutePrefix] sections contain the IPv6
2573 prefix routes that are announced via Router Advertisements. See
2574 <ulink url="https://tools.ietf.org/html/rfc4191">RFC 4191</ulink>
2575 for further details.</para>
2576
2577 <variablelist class='network-directives'>
2578
2579 <varlistentry>
2580 <term><varname>Route=</varname></term>
2581
2582 <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
2583 IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
2584 separated by a <literal>/</literal> character. Use multiple [IPv6PrefixRoutes] sections to configure
2585 multiple IPv6 prefix routes.</para></listitem>
2586 </varlistentry>
2587
2588 <varlistentry>
2589 <term><varname>LifetimeSec=</varname></term>
2590
2591 <listitem><para>Lifetime for the route prefix measured in
2592 seconds. <varname>LifetimeSec=</varname> defaults to 604800 seconds (one week).
2593 </para></listitem>
2594 </varlistentry>
2595
2596 </variablelist>
2597 </refsect1>
2598
2599 <refsect1>
2600 <title>[Bridge] Section Options</title>
2601 <para>The [Bridge] section accepts the following keys:</para>
2602 <variablelist class='network-directives'>
2603 <varlistentry>
2604 <term><varname>UnicastFlood=</varname></term>
2605 <listitem>
2606 <para>Takes a boolean. Controls whether the bridge should flood
2607 traffic for which an FDB entry is missing and the destination
2608 is unknown through this port. When unset, the kernel's default will be used.
2609 </para>
2610 </listitem>
2611 </varlistentry>
2612 <varlistentry>
2613 <term><varname>MulticastFlood=</varname></term>
2614 <listitem>
2615 <para>Takes a boolean. Controls whether the bridge should flood
2616 traffic for which an MDB entry is missing and the destination
2617 is unknown through this port. When unset, the kernel's default will be used.
2618 </para>
2619 </listitem>
2620 </varlistentry>
2621 <varlistentry>
2622 <term><varname>MulticastToUnicast=</varname></term>
2623 <listitem>
2624 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2625 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2626 When unset, the kernel's default will be used.
2627 </para>
2628 </listitem>
2629 </varlistentry>
2630 <varlistentry>
2631 <term><varname>NeighborSuppression=</varname></term>
2632 <listitem>
2633 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2634 this port. When unset, the kernel's default will be used.
2635 </para>
2636 </listitem>
2637 </varlistentry>
2638 <varlistentry>
2639 <term><varname>Learning=</varname></term>
2640 <listitem>
2641 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2642 this port. When unset, the kernel's default will be used.
2643 </para>
2644 </listitem>
2645 </varlistentry>
2646 <varlistentry>
2647 <term><varname>HairPin=</varname></term>
2648 <listitem>
2649 <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
2650 was received. When this flag is false, then the bridge will not forward traffic back out of the
2651 receiving port. When unset, the kernel's default will be used.</para>
2652 </listitem>
2653 </varlistentry>
2654 <varlistentry>
2655 <term><varname>UseBPDU=</varname></term>
2656 <listitem>
2657 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2658 processed by the bridge port. When unset, the kernel's default will be used.</para>
2659 </listitem>
2660 </varlistentry>
2661 <varlistentry>
2662 <term><varname>FastLeave=</varname></term>
2663 <listitem>
2664 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2665 traffic on a port that receives an IGMP Leave message. It is only used with
2666 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.</para>
2667 </listitem>
2668 </varlistentry>
2669 <varlistentry>
2670 <term><varname>AllowPortToBeRoot=</varname></term>
2671 <listitem>
2672 <para>Takes a boolean. Configures whether a given port is allowed to
2673 become a root port. Only used when STP is enabled on the bridge.
2674 When unset, the kernel's default will be used.</para>
2675 </listitem>
2676 </varlistentry>
2677 <varlistentry>
2678 <term><varname>ProxyARP=</varname></term>
2679 <listitem>
2680 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2681 When unset, the kernel's default will be used.</para>
2682 </listitem>
2683 </varlistentry>
2684 <varlistentry>
2685 <term><varname>ProxyARPWiFi=</varname></term>
2686 <listitem>
2687 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2688 which meets extended requirements by IEEE 802.11 and Hotspot 2.0 specifications.
2689 When unset, the kernel's default will be used.</para>
2690 </listitem>
2691 </varlistentry>
2692 <varlistentry>
2693 <term><varname>MulticastRouter=</varname></term>
2694 <listitem>
2695 <para>Configures this port for having multicast routers attached. A port with a multicast
2696 router will receive all multicast traffic. Takes one of <literal>no</literal>
2697 to disable multicast routers on this port, <literal>query</literal> to let the system detect
2698 the presence of routers, <literal>permanent</literal> to permanently enable multicast traffic
2699 forwarding on this port, or <literal>temporary</literal> to enable multicast routers temporarily
2700 on this port, not depending on incoming queries. When unset, the kernel's default will be used.</para>
2701 </listitem>
2702 </varlistentry>
2703 <varlistentry>
2704 <term><varname>Cost=</varname></term>
2705 <listitem>
2706 <para>Sets the "cost" of sending packets of this interface.
2707 Each port in a bridge may have a different speed and the cost
2708 is used to decide which link to use. Faster interfaces
2709 should have lower costs. It is an integer value between 1 and
2710 65535.</para>
2711 </listitem>
2712 </varlistentry>
2713 <varlistentry>
2714 <term><varname>Priority=</varname></term>
2715 <listitem>
2716 <para>Sets the "priority" of sending packets on this interface.
2717 Each port in a bridge may have a different priority which is used
2718 to decide which link to use. Lower value means higher priority.
2719 It is an integer value between 0 to 63. Networkd does not set any
2720 default, meaning the kernel default value of 32 is used.</para>
2721 </listitem>
2722 </varlistentry>
2723 </variablelist>
2724 </refsect1>
2725 <refsect1>
2726 <title>[BridgeFDB] Section Options</title>
2727 <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
2728 keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.</para>
2729
2730 <variablelist class='network-directives'>
2731 <varlistentry>
2732 <term><varname>MACAddress=</varname></term>
2733 <listitem>
2734 <para>As in the [Network] section. This key is mandatory.</para>
2735 </listitem>
2736 </varlistentry>
2737 <varlistentry>
2738 <term><varname>Destination=</varname></term>
2739 <listitem>
2740 <para>Takes an IP address of the destination VXLAN tunnel endpoint.</para>
2741 </listitem>
2742 </varlistentry>
2743 <varlistentry>
2744 <term><varname>VLANId=</varname></term>
2745 <listitem>
2746 <para>The VLAN ID for the new static MAC table entry. If
2747 omitted, no VLAN ID information is appended to the new static MAC
2748 table entry.</para>
2749 </listitem>
2750 </varlistentry>
2751 <varlistentry>
2752 <term><varname>VNI=</varname></term>
2753 <listitem>
2754 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2755 the remote VXLAN tunnel endpoint. Takes a number in the range 1…16777215.
2756 Defaults to unset.</para>
2757 </listitem>
2758 </varlistentry>
2759 <varlistentry>
2760 <term><varname>AssociatedWith=</varname></term>
2761 <listitem>
2762 <para>Specifies where the address is associated with. Takes one of <literal>use</literal>,
2763 <literal>self</literal>, <literal>master</literal> or <literal>router</literal>.
2764 <literal>use</literal> means the address is in use. User space can use this option to
2765 indicate to the kernel that the fdb entry is in use. <literal>self</literal> means
2766 the address is associated with the port drivers fdb. Usually hardware. <literal>master</literal>
2767 means the address is associated with master devices fdb. <literal>router</literal> means
2768 the destination address is associated with a router. Note that it's valid if the referenced
2769 device is a VXLAN type device and has route shortcircuit enabled. Defaults to <literal>self</literal>.</para>
2770 </listitem>
2771 </varlistentry>
2772 </variablelist>
2773 </refsect1>
2774 <refsect1>
2775 <title>[BridgeMDB] Section Options</title>
2776 <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
2777 keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.</para>
2778
2779 <variablelist class='network-directives'>
2780 <varlistentry>
2781 <term><varname>MulticastGroupAddress=</varname></term>
2782 <listitem>
2783 <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.</para>
2784 </listitem>
2785 </varlistentry>
2786 <varlistentry>
2787 <term><varname>VLANId=</varname></term>
2788 <listitem>
2789 <para>The VLAN ID for the new entry. Valid ranges are 0 (no VLAN) to 4094. Optional, defaults to 0.</para>
2790 </listitem>
2791 </varlistentry>
2792 </variablelist>
2793 </refsect1>
2794
2795 <refsect1>
2796 <title>[LLDP] Section Options</title>
2797 <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
2798 keys:</para>
2799 <variablelist class='network-directives'>
2800 <varlistentry>
2801 <term><varname>MUDURL=</varname></term>
2802 <listitem>
2803 <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
2804 LLDP packets. The syntax and semantics are the same as for <varname>MUDURL=</varname> in the
2805 [DHCPv4] section described above.</para>
2806
2807 <para>The MUD URLs received via LLDP packets are saved and can be read using the
2808 <function>sd_lldp_neighbor_get_mud_url()</function> function.</para>
2809 </listitem>
2810 </varlistentry>
2811 </variablelist>
2812 </refsect1>
2813
2814 <refsect1>
2815 <title>[CAN] Section Options</title>
2816 <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
2817 following keys:</para>
2818 <variablelist class='network-directives'>
2819 <varlistentry>
2820 <term><varname>BitRate=</varname></term>
2821 <listitem>
2822 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of 1000 can
2823 be used here. Takes a number in the range 1…4294967295.</para>
2824 </listitem>
2825 </varlistentry>
2826 <varlistentry>
2827 <term><varname>SamplePoint=</varname></term>
2828 <listitem>
2829 <para>Optional sample point in percent with one decimal (e.g. <literal>75%</literal>,
2830 <literal>87.5%</literal>) or permille (e.g. <literal>875‰</literal>).</para>
2831 </listitem>
2832 </varlistentry>
2833 <varlistentry>
2834 <term><varname>DataBitRate=</varname></term>
2835 <term><varname>DataSamplePoint=</varname></term>
2836 <listitem>
2837 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
2838 analogous to the <varname>BitRate=</varname> and <varname>SamplePoint=</varname> keys.</para>
2839 </listitem>
2840 </varlistentry>
2841 <varlistentry>
2842 <term><varname>FDMode=</varname></term>
2843 <listitem>
2844 <para>Takes a boolean. When <literal>yes</literal>, CAN-FD mode is enabled for the interface.
2845 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
2846 the <varname>DataBitRate=</varname> and <varname>DataSamplePoint=</varname> keys.</para>
2847 </listitem>
2848 </varlistentry>
2849 <varlistentry>
2850 <term><varname>FDNonISO=</varname></term>
2851 <listitem>
2852 <para>Takes a boolean. When <literal>yes</literal>, non-ISO CAN-FD mode is enabled for the
2853 interface. When unset, the kernel's default will be used.</para>
2854 </listitem>
2855 </varlistentry>
2856 <varlistentry>
2857 <term><varname>RestartSec=</varname></term>
2858 <listitem>
2859 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2860 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2861 be specified using decimals (e.g. <literal>0.1s</literal>) or a <literal>ms</literal> or
2862 <literal>us</literal> postfix. Using <literal>infinity</literal> or <literal>0</literal> will turn the
2863 automatic restart off. By default automatic restart is disabled.</para>
2864 </listitem>
2865 </varlistentry>
2866 <varlistentry>
2867 <term><varname>Termination=</varname></term>
2868 <listitem>
2869 <para>Takes a boolean. When <literal>yes</literal>, the termination resistor will be selected for
2870 the bias network. When unset, the kernel's default will be used.</para>
2871 </listitem>
2872 </varlistentry>
2873 <varlistentry>
2874 <term><varname>TripleSampling=</varname></term>
2875 <listitem>
2876 <para>Takes a boolean. When <literal>yes</literal>, three samples (instead of one) are used to determine
2877 the value of a received bit by majority rule. When unset, the kernel's default will be used.</para>
2878 </listitem>
2879 </varlistentry>
2880 <varlistentry>
2881 <term><varname>BusErrorReporting=</varname></term>
2882 <listitem>
2883 <para>Takes a boolean. When <literal>yes</literal>, reporting of CAN bus errors is activated
2884 (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
2885 unable to send recessive bit, bus overload, active error announcement, error occurred on
2886 transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
2887 single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.</para>
2888 </listitem>
2889 </varlistentry>
2890 <varlistentry>
2891 <term><varname>ListenOnly=</varname></term>
2892 <listitem>
2893 <para>Takes a boolean. When <literal>yes</literal>, listen-only mode is enabled. When the
2894 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
2895 bit. Listen-only mode is important to debug CAN networks without interfering with the
2896 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
2897 </para>
2898 </listitem>
2899 </varlistentry>
2900 </variablelist>
2901 </refsect1>
2902
2903 <refsect1>
2904 <title>[QDisc] Section Options</title>
2905 <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).</para>
2906
2907 <variablelist class='network-directives'>
2908 <varlistentry>
2909 <term><varname>Parent=</varname></term>
2910 <listitem>
2911 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of <literal>clsact</literal>
2912 or <literal>ingress</literal>. This is mandatory.</para>
2913 </listitem>
2914 </varlistentry>
2915
2916 <xi:include href="tc.xml" xpointer="qdisc-handle" />
2917 </variablelist>
2918 </refsect1>
2919
2920 <refsect1>
2921 <title>[NetworkEmulator] Section Options</title>
2922 <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
2923 can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
2924 applications, or limit the bandwidth usage of a particular service to simulate internet connections.
2925 </para>
2926
2927 <variablelist class='network-directives'>
2928 <xi:include href="tc.xml" xpointer="qdisc-parent" />
2929 <xi:include href="tc.xml" xpointer="qdisc-handle" />
2930
2931 <varlistentry>
2932 <term><varname>DelaySec=</varname></term>
2933 <listitem>
2934 <para>Specifies the fixed amount of delay to be added to all packets going out of the
2935 interface. Defaults to unset.</para>
2936 </listitem>
2937 </varlistentry>
2938
2939 <varlistentry>
2940 <term><varname>DelayJitterSec=</varname></term>
2941 <listitem>
2942 <para>Specifies the chosen delay to be added to the packets outgoing to the network
2943 interface. Defaults to unset.</para>
2944 </listitem>
2945 </varlistentry>
2946
2947 <varlistentry>
2948 <term><varname>PacketLimit=</varname></term>
2949 <listitem>
2950 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
2951 An unsigned integer in the range 0–4294967294. Defaults to 1000.</para>
2952 </listitem>
2953 </varlistentry>
2954
2955 <varlistentry>
2956 <term><varname>LossRate=</varname></term>
2957 <listitem>
2958 <para>Specifies an independent loss probability to be added to the packets outgoing from the
2959 network interface. Takes a percentage value, suffixed with "%". Defaults to unset.</para>
2960 </listitem>
2961 </varlistentry>
2962
2963 <varlistentry>
2964 <term><varname>DuplicateRate=</varname></term>
2965 <listitem>
2966 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
2967 Takes a percentage value, suffixed with "%". Defaults to unset.</para>
2968 </listitem>
2969 </varlistentry>
2970 </variablelist>
2971 </refsect1>
2972
2973 <refsect1>
2974 <title>[TokenBucketFilter] Section Options</title>
2975 <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
2976 (tbf).</para>
2977
2978 <variablelist class='network-directives'>
2979 <xi:include href="tc.xml" xpointer="qdisc-parent" />
2980 <xi:include href="tc.xml" xpointer="qdisc-handle" />
2981
2982 <varlistentry>
2983 <term><varname>LatencySec=</varname></term>
2984 <listitem>
2985 <para>Specifies the latency parameter, which specifies the maximum amount of time a
2986 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.</para>
2987 </listitem>
2988 </varlistentry>
2989
2990 <varlistentry>
2991 <term><varname>LimitBytes=</varname></term>
2992 <listitem>
2993 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
2994 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
2995 respectively, to the base of 1024. Defaults to unset.</para>
2996 </listitem>
2997 </varlistentry>
2998
2999 <varlistentry>
3000 <term><varname>BurstBytes=</varname></term>
3001 <listitem>
3002 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
3003 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
3004 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to
3005 unset.</para>
3006 </listitem>
3007 </varlistentry>
3008
3009 <varlistentry>
3010 <term><varname>Rate=</varname></term>
3011 <listitem>
3012 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
3013 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of 1000.
3014 Defaults to unset.</para>
3015 </listitem>
3016 </varlistentry>
3017
3018 <varlistentry>
3019 <term><varname>MPUBytes=</varname></term>
3020 <listitem>
3021 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
3022 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3023 Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to zero.</para>
3024 </listitem>
3025 </varlistentry>
3026
3027 <varlistentry>
3028 <term><varname>PeakRate=</varname></term>
3029 <listitem>
3030 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
3031 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
3032 1000. Defaults to unset.</para>
3033 </listitem>
3034 </varlistentry>
3035
3036 <varlistentry>
3037 <term><varname>MTUBytes=</varname></term>
3038 <listitem>
3039 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
3040 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024.
3041 Defaults to unset.</para>
3042 </listitem>
3043 </varlistentry>
3044 </variablelist>
3045 </refsect1>
3046
3047 <refsect1>
3048 <title>[PIE] Section Options</title>
3049 <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
3050 controller-Enhanced (PIE).</para>
3051
3052 <variablelist class='network-directives'>
3053 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3054 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3055
3056 <varlistentry>
3057 <term><varname>PacketLimit=</varname></term>
3058 <listitem>
3059 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3060 incoming packets are dropped. An unsigned integer in the range 1…4294967294. Defaults to unset and
3061 kernel's default is used.</para>
3062 </listitem>
3063 </varlistentry>
3064 </variablelist>
3065 </refsect1>
3066
3067 <refsect1>
3068 <title>[FlowQueuePIE] Section Options</title>
3069 <para>The <literal>[FlowQueuePIE]</literal> section manages the queueing discipline
3070 (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).</para>
3071
3072 <variablelist class='network-directives'>
3073 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3074 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3075
3076 <varlistentry>
3077 <term><varname>PacketLimit=</varname></term>
3078 <listitem>
3079 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3080 incoming packets are dropped. An unsigned integer ranges 1 to 4294967294. Defaults to unset and
3081 kernel's default is used.</para>
3082 </listitem>
3083 </varlistentry>
3084 </variablelist>
3085 </refsect1>
3086
3087 <refsect1>
3088 <title>[StochasticFairBlue] Section Options</title>
3089 <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
3090 (sfb).</para>
3091
3092 <variablelist class='network-directives'>
3093 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3094 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3095
3096 <varlistentry>
3097 <term><varname>PacketLimit=</varname></term>
3098 <listitem>
3099 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3100 incoming packets are dropped. An unsigned integer in the range 0–4294967294. Defaults to unset and
3101 kernel's default is used.</para>
3102 </listitem>
3103 </varlistentry>
3104 </variablelist>
3105 </refsect1>
3106
3107 <refsect1>
3108 <title>[StochasticFairnessQueueing] Section Options</title>
3109 <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
3110 fairness queueing (sfq).</para>
3111
3112 <variablelist class='network-directives'>
3113 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3114 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3115
3116 <varlistentry>
3117 <term><varname>PerturbPeriodSec=</varname></term>
3118 <listitem>
3119 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.</para>
3120 </listitem>
3121 </varlistentry>
3122 </variablelist>
3123 </refsect1>
3124
3125 <refsect1>
3126 <title>[BFIFO] Section Options</title>
3127 <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
3128 Out (bfifo).</para>
3129
3130 <variablelist class='network-directives'>
3131 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3132 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3133
3134 <varlistentry>
3135 <term><varname>LimitBytes=</varname></term>
3136 <listitem>
3137 <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
3138 in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
3139 reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
3140 as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and
3141 kernel default is used.</para>
3142 </listitem>
3143 </varlistentry>
3144 </variablelist>
3145 </refsect1>
3146
3147 <refsect1>
3148 <title>[PFIFO] Section Options</title>
3149 <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
3150 (pfifo).</para>
3151
3152 <variablelist class='network-directives'>
3153 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3154 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3155
3156 <varlistentry>
3157 <term><varname>PacketLimit=</varname></term>
3158 <listitem>
3159 <para>Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents
3160 overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this
3161 limit is reached, incoming packets are dropped. An unsigned integer in the range
3162 0–4294967294. Defaults to unset and kernel's default is used.</para>
3163 </listitem>
3164 </varlistentry>
3165 </variablelist>
3166 </refsect1>
3167
3168 <refsect1>
3169 <title>[PFIFOHeadDrop] Section Options</title>
3170 <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
3171 Head Drop (pfifo_head_drop).</para>
3172
3173 <variablelist class='network-directives'>
3174 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3175 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3176
3177 <varlistentry>
3178 <term><varname>PacketLimit=</varname></term>
3179 <listitem>
3180 <para>As in [PFIFO] section.</para></listitem>
3181 </varlistentry>
3182 </variablelist>
3183 </refsect1>
3184
3185 <refsect1>
3186 <title>[PFIFOFast] Section Options</title>
3187 <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
3188 (pfifo_fast).</para>
3189
3190 <variablelist class='network-directives'>
3191 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3192 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3193 </variablelist>
3194 </refsect1>
3195
3196 <refsect1>
3197 <title>[CAKE] Section Options</title>
3198 <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
3199 (CAKE).</para>
3200
3201 <variablelist class='network-directives'>
3202 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3203 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3204
3205 <varlistentry>
3206 <term><varname>OverheadBytes=</varname></term>
3207 <listitem>
3208 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative. Takes
3209 an integer in the range from -64 to 256. Defaults to unset and kernel's default is used.</para>
3210 </listitem>
3211 </varlistentry>
3212
3213 <varlistentry>
3214 <term><varname>Bandwidth=</varname></term>
3215 <listitem>
3216 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
3217 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of 1000. Defaults to
3218 unset and kernel's default is used.</para>
3219 </listitem>
3220 </varlistentry>
3221 </variablelist>
3222 </refsect1>
3223
3224 <refsect1>
3225 <title>[ControlledDelay] Section Options</title>
3226 <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
3227 controlled delay (CoDel).</para>
3228
3229 <variablelist class='network-directives'>
3230 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3231 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3232
3233 <varlistentry>
3234 <term><varname>PacketLimit=</varname></term>
3235 <listitem>
3236 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3237 incoming packets are dropped. An unsigned integer in the range 0–4294967294. Defaults to unset and
3238 kernel's default is used.</para>
3239 </listitem>
3240 </varlistentry>
3241
3242 <varlistentry>
3243 <term><varname>TargetSec=</varname></term>
3244 <listitem>
3245 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
3246 Defaults to unset and kernel's default is used.</para>
3247 </listitem>
3248 </varlistentry>
3249
3250 <varlistentry>
3251 <term><varname>IntervalSec=</varname></term>
3252 <listitem>
3253 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
3254 become too stale. Defaults to unset and kernel's default is used.</para>
3255 </listitem>
3256 </varlistentry>
3257
3258 <varlistentry>
3259 <term><varname>ECN=</varname></term>
3260 <listitem>
3261 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3262 unset and kernel's default is used.</para>
3263 </listitem>
3264 </varlistentry>
3265
3266 <varlistentry>
3267 <term><varname>CEThresholdSec=</varname></term>
3268 <listitem>
3269 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3270 Congestion Experienced (CE). Defaults to unset and kernel's default is used.</para>
3271 </listitem>
3272 </varlistentry>
3273 </variablelist>
3274 </refsect1>
3275
3276 <refsect1>
3277 <title>[DeficitRoundRobinScheduler] Section Options</title>
3278 <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
3279 Robin Scheduler (DRR).</para>
3280
3281 <variablelist class='network-directives'>
3282 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3283 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3284 </variablelist>
3285 </refsect1>
3286
3287 <refsect1>
3288 <title>[DeficitRoundRobinSchedulerClass] Section Options</title>
3289 <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
3290 Robin Scheduler (DRR).</para>
3291
3292 <variablelist class='network-directives'>
3293 <xi:include href="tc.xml" xpointer="tclass-parent" />
3294 <xi:include href="tc.xml" xpointer="tclass-classid" />
3295
3296 <varlistentry>
3297 <term><varname>QuantumBytes=</varname></term>
3298 <listitem>
3299 <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
3300 to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3301 Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to the MTU of the
3302 interface.</para>
3303 </listitem>
3304 </varlistentry>
3305
3306 </variablelist>
3307 </refsect1>
3308
3309 <refsect1>
3310 <title>[EnhancedTransmissionSelection] Section Options</title>
3311 <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
3312 Transmission Selection (ETS).</para>
3313
3314 <variablelist class='network-directives'>
3315 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3316 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3317
3318 <varlistentry>
3319 <term><varname>Bands=</varname></term>
3320 <listitem>
3321 <para>Specifies the number of bands. An unsigned integer in the range 1–16. This value has to be at
3322 least large enough to cover the strict bands specified through the <varname>StrictBands=</varname>
3323 and bandwidth-sharing bands specified in <varname>QuantumBytes=</varname>.</para>
3324 </listitem>
3325 </varlistentry>
3326
3327 <varlistentry>
3328 <term><varname>StrictBands=</varname></term>
3329 <listitem>
3330 <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
3331 the range 1–16.</para>
3332 </listitem>
3333 </varlistentry>
3334
3335 <varlistentry>
3336 <term><varname>QuantumBytes=</varname></term>
3337 <listitem>
3338 <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
3339 suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3340 respectively, to the base of 1024. This setting can be specified multiple times. If an empty
3341 string is assigned, then the all previous assignments are cleared.</para>
3342 </listitem>
3343 </varlistentry>
3344
3345 <varlistentry>
3346 <term><varname>PriorityMap=</varname></term>
3347 <listitem>
3348 <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
3349 separated list of numbers. The first number indicates which band the packets with priority 0 should
3350 be put to, the second is for priority 1, and so on. There can be up to 16 numbers in the list. If
3351 there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
3352 the last one. Each band number must be in the range 0…255. This setting can be specified multiple
3353 times. If an empty string is assigned, then the all previous assignments are cleared.</para>
3354 </listitem>
3355 </varlistentry>
3356 </variablelist>
3357 </refsect1>
3358
3359 <refsect1>
3360 <title>[GenericRandomEarlyDetection] Section Options</title>
3361 <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
3362 Early Detection (GRED).</para>
3363
3364 <variablelist class='network-directives'>
3365 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3366 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3367
3368 <varlistentry>
3369 <term><varname>VirtualQueues=</varname></term>
3370 <listitem>
3371 <para>Specifies the number of virtual queues. Takes a integer in the range 1…16. Defaults to unset
3372 and kernel's default is used.</para>
3373 </listitem>
3374 </varlistentry>
3375
3376 <varlistentry>
3377 <term><varname>DefaultVirtualQueue=</varname></term>
3378 <listitem>
3379 <para>Specifies the number of default virtual queue. This must be less than <varname>VirtualQueue=</varname>.
3380 Defaults to unset and kernel's default is used.</para>
3381 </listitem>
3382 </varlistentry>
3383
3384 <varlistentry>
3385 <term><varname>GenericRIO=</varname></term>
3386 <listitem>
3387 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
3388 unset and kernel's default is used.</para>
3389 </listitem>
3390 </varlistentry>
3391 </variablelist>
3392 </refsect1>
3393
3394 <refsect1>
3395 <title>[FairQueueingControlledDelay] Section Options</title>
3396 <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
3397 controlled delay (FQ-CoDel).</para>
3398
3399 <variablelist class='network-directives'>
3400 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3401 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3402
3403 <varlistentry>
3404 <term><varname>PacketLimit=</varname></term>
3405 <listitem>
3406 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3407 dropped. Defaults to unset and kernel's default is used.</para>
3408 </listitem>
3409 </varlistentry>
3410
3411 <varlistentry>
3412 <term><varname>MemoryLimitBytes=</varname></term>
3413 <listitem>
3414 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
3415 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3416 respectively, to the base of 1024. Defaults to unset and kernel's default is used.</para>
3417 </listitem>
3418 </varlistentry>
3419
3420 <varlistentry>
3421 <term><varname>Flows=</varname></term>
3422 <listitem>
3423 <para>Specifies the number of flows into which the incoming packets are classified.
3424 Defaults to unset and kernel's default is used.</para>
3425 </listitem>
3426 </varlistentry>
3427
3428 <varlistentry>
3429 <term><varname>TargetSec=</varname></term>
3430 <listitem>
3431 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
3432 Defaults to unset and kernel's default is used.</para>
3433 </listitem>
3434 </varlistentry>
3435
3436 <varlistentry>
3437 <term><varname>IntervalSec=</varname></term>
3438 <listitem>
3439 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
3440 become too stale. Defaults to unset and kernel's default is used.</para>
3441 </listitem>
3442 </varlistentry>
3443
3444 <varlistentry>
3445 <term><varname>QuantumBytes=</varname></term>
3446 <listitem>
3447 <para>Specifies the number of bytes used as the "deficit" in the fair queuing algorithm timespan.
3448 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3449 respectively, to the base of 1024. Defaults to unset and kernel's default is used.</para>
3450 </listitem>
3451 </varlistentry>
3452
3453 <varlistentry>
3454 <term><varname>ECN=</varname></term>
3455 <listitem>
3456 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3457 unset and kernel's default is used.</para>
3458 </listitem>
3459 </varlistentry>
3460
3461 <varlistentry>
3462 <term><varname>CEThresholdSec=</varname></term>
3463 <listitem>
3464 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3465 Congestion Experienced (CE). Defaults to unset and kernel's default is used.</para>
3466 </listitem>
3467 </varlistentry>
3468 </variablelist>
3469 </refsect1>
3470
3471 <refsect1>
3472 <title>[FairQueueing] Section Options</title>
3473 <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
3474 (FQ).</para>
3475
3476 <variablelist class='network-directives'>
3477 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3478 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3479
3480 <varlistentry>
3481 <term><varname>PacketLimit=</varname></term>
3482 <listitem>
3483 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3484 dropped. Defaults to unset and kernel's default is used.</para>
3485 </listitem>
3486 </varlistentry>
3487
3488 <varlistentry>
3489 <term><varname>FlowLimit=</varname></term>
3490 <listitem>
3491 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
3492 unset and kernel's default is used.</para>
3493 </listitem>
3494 </varlistentry>
3495
3496 <varlistentry>
3497 <term><varname>QuantumBytes=</varname></term>
3498 <listitem>
3499 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
3500 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3501 Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and kernel's
3502 default is used.</para>
3503 </listitem>
3504 </varlistentry>
3505
3506 <varlistentry>
3507 <term><varname>InitialQuantumBytes=</varname></term>
3508 <listitem>
3509 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
3510 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
3511 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and
3512 kernel's default is used.</para>
3513 </listitem>
3514 </varlistentry>
3515
3516 <varlistentry>
3517 <term><varname>MaximumRate=</varname></term>
3518 <listitem>
3519 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
3520 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
3521 1000. Defaults to unset and kernel's default is used.</para>
3522 </listitem>
3523 </varlistentry>
3524
3525 <varlistentry>
3526 <term><varname>Buckets=</varname></term>
3527 <listitem>
3528 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
3529 kernel's default is used.</para>
3530 </listitem>
3531 </varlistentry>
3532
3533 <varlistentry>
3534 <term><varname>OrphanMask=</varname></term>
3535 <listitem>
3536 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
3537 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
3538 kernel's default is used.</para>
3539 </listitem>
3540 </varlistentry>
3541
3542 <varlistentry>
3543 <term><varname>Pacing=</varname></term>
3544 <listitem>
3545 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
3546 default is used.</para>
3547 </listitem>
3548 </varlistentry>
3549
3550 <varlistentry>
3551 <term><varname>CEThresholdSec=</varname></term>
3552 <listitem>
3553 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3554 Congestion Experienced (CE). Defaults to unset and kernel's default is used.</para>
3555 </listitem>
3556 </varlistentry>
3557 </variablelist>
3558 </refsect1>
3559
3560 <refsect1>
3561 <title>[TrivialLinkEqualizer] Section Options</title>
3562 <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
3563 equalizer (teql).</para>
3564
3565 <variablelist class='network-directives'>
3566 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3567 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3568
3569 <varlistentry>
3570 <term><varname>Id=</varname></term>
3571 <listitem>
3572 <para>Specifies the interface ID <literal>N</literal> of teql. Defaults to <literal>0</literal>.
3573 Note that when teql is used, currently, the module <constant>sch_teql</constant> with
3574 <constant>max_equalizers=N+1</constant> option must be loaded before
3575 <command>systemd-networkd</command> is started.</para>
3576 </listitem>
3577 </varlistentry>
3578 </variablelist>
3579 </refsect1>
3580
3581 <refsect1>
3582 <title>[HierarchyTokenBucket] Section Options</title>
3583 <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
3584 bucket (htb).</para>
3585
3586 <variablelist class='network-directives'>
3587 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3588 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3589
3590 <varlistentry>
3591 <term><varname>DefaultClass=</varname></term>
3592 <listitem>
3593 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
3594 to the class. Defaults to unset.</para>
3595 </listitem>
3596 </varlistentry>
3597
3598 <varlistentry>
3599 <term><varname>RateToQuantum=</varname></term>
3600 <listitem>
3601 <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
3602 configured in <varname>Rate=</varname> by <varname>RateToQuantum=</varname>.</para>
3603 </listitem>
3604 </varlistentry>
3605 </variablelist>
3606 </refsect1>
3607
3608 <refsect1>
3609 <title>[HierarchyTokenBucketClass] Section Options</title>
3610 <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
3611 (htb).</para>
3612
3613 <variablelist class='network-directives'>
3614 <xi:include href="tc.xml" xpointer="tclass-parent" />
3615 <xi:include href="tc.xml" xpointer="tclass-classid" />
3616
3617 <varlistentry>
3618 <term><varname>Priority=</varname></term>
3619 <listitem>
3620 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
3621 priority field are tried for packets first.</para>
3622 </listitem>
3623 </varlistentry>
3624
3625 <varlistentry>
3626 <term><varname>QuantumBytes=</varname></term>
3627 <listitem>
3628 <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
3629 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
3630 1024.</para>
3631 </listitem>
3632 </varlistentry>
3633
3634 <varlistentry>
3635 <term><varname>MTUBytes=</varname></term>
3636 <listitem>
3637 <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
3638 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024.</para>
3639 </listitem>
3640 </varlistentry>
3641
3642 <varlistentry>
3643 <term><varname>OverheadBytes=</varname></term>
3644 <listitem>
3645 <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
3646 computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3647 Megabytes, or Gigabytes, respectively, to the base of 1024.</para>
3648 </listitem>
3649 </varlistentry>
3650
3651 <varlistentry>
3652 <term><varname>Rate=</varname></term>
3653 <listitem>
3654 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
3655 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
3656 to the base of 1000. This setting is mandatory.</para>
3657 </listitem>
3658 </varlistentry>
3659
3660 <varlistentry>
3661 <term><varname>CeilRate=</varname></term>
3662 <listitem>
3663 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
3664 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
3665 respectively, to the base of 1000. When unset, the value specified with <varname>Rate=</varname>
3666 is used.</para>
3667 </listitem>
3668 </varlistentry>
3669
3670 <varlistentry>
3671 <term><varname>BufferBytes=</varname></term>
3672 <listitem>
3673 <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
3674 with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
3675 to the base of 1024.</para>
3676 </listitem>
3677 </varlistentry>
3678
3679 <varlistentry>
3680 <term><varname>CeilBufferBytes=</varname></term>
3681 <listitem>
3682 <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
3683 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3684 respectively, to the base of 1024.</para>
3685 </listitem>
3686 </varlistentry>
3687 </variablelist>
3688 </refsect1>
3689
3690 <refsect1>
3691 <title>[HeavyHitterFilter] Section Options</title>
3692 <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
3693 (hhf).</para>
3694
3695 <variablelist class='network-directives'>
3696 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3697 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3698
3699 <varlistentry>
3700 <term><varname>PacketLimit=</varname></term>
3701 <listitem>
3702 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3703 incoming packets are dropped. An unsigned integer in the range 0–4294967294. Defaults to unset and
3704 kernel's default is used.</para>
3705 </listitem>
3706 </varlistentry>
3707 </variablelist>
3708 </refsect1>
3709
3710 <refsect1>
3711 <title>[QuickFairQueueing] Section Options</title>
3712 <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
3713 (QFQ).</para>
3714
3715 <variablelist class='network-directives'>
3716 <xi:include href="tc.xml" xpointer="qdisc-parent" />
3717 <xi:include href="tc.xml" xpointer="qdisc-handle" />
3718 </variablelist>
3719 </refsect1>
3720
3721 <refsect1>
3722 <title>[QuickFairQueueingClass] Section Options</title>
3723 <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
3724 (qfq).</para>
3725
3726 <variablelist class='network-directives'>
3727 <xi:include href="tc.xml" xpointer="tclass-parent" />
3728 <xi:include href="tc.xml" xpointer="tclass-classid" />
3729
3730 <varlistentry>
3731 <term><varname>Weight=</varname></term>
3732 <listitem>
3733 <para>Specifies the weight of the class. Takes an integer in the range 1…1023. Defaults to
3734 unset in which case the kernel default is used.</para>
3735 </listitem>
3736 </varlistentry>
3737
3738 <varlistentry>
3739 <term><varname>MaxPacketBytes=</varname></term>
3740 <listitem>
3741 <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the
3742 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
3743 1024. When unset, the kernel default is used.</para>
3744 </listitem>
3745 </varlistentry>
3746 </variablelist>
3747 </refsect1>
3748
3749 <refsect1>
3750 <title>[BridgeVLAN] Section Options</title>
3751 <para>The [BridgeVLAN] section manages the VLAN ID configuration of a bridge port and accepts the
3752 following keys. Specify several [BridgeVLAN] sections to configure several VLAN entries. The
3753 <varname>VLANFiltering=</varname> option has to be enabled, see the [Bridge] section in
3754 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
3755
3756 <variablelist class='network-directives'>
3757 <varlistentry>
3758 <term><varname>VLAN=</varname></term>
3759 <listitem>
3760 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
3761 from 1 to 4094.</para>
3762 </listitem>
3763 </varlistentry>
3764 <varlistentry>
3765 <term><varname>EgressUntagged=</varname></term>
3766 <listitem>
3767 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
3768 <varname>EgressUntagged=</varname> implicates the use of <varname>VLAN=</varname> above and will enable the
3769 VLAN ID for ingress as well. This can be either a single ID or a range M-N.</para>
3770 </listitem>
3771 </varlistentry>
3772 <varlistentry>
3773 <term><varname>PVID=</varname></term>
3774 <listitem>
3775 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
3776 <varname>PVID=</varname> can be used only once. Configuring <varname>PVID=</varname> implicates the use of
3777 <varname>VLAN=</varname> above and will enable the VLAN ID for ingress as well.</para>
3778 </listitem>
3779 </varlistentry>
3780 </variablelist>
3781 </refsect1>
3782
3783 <refsect1>
3784 <title>Examples</title>
3785 <example>
3786 <title>Static network configuration</title>
3787
3788 <programlisting># /etc/systemd/network/50-static.network
3789 [Match]
3790 Name=enp2s0
3791
3792 [Network]
3793 Address=192.168.0.15/24
3794 Gateway=192.168.0.1</programlisting>
3795
3796 <para>This brings interface <literal>enp2s0</literal> up with a static address. The
3797 specified gateway will be used for a default route.</para>
3798 </example>
3799
3800 <example>
3801 <title>DHCP on ethernet links</title>
3802
3803 <programlisting># /etc/systemd/network/80-dhcp.network
3804 [Match]
3805 Name=en*
3806
3807 [Network]
3808 DHCP=yes</programlisting>
3809
3810 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
3811 <literal>en</literal> (i.e. ethernet interfaces).</para>
3812 </example>
3813
3814 <example>
3815 <title>IPv6 Prefix Delegation</title>
3816
3817 <programlisting># /etc/systemd/network/55-ipv6-pd-upstream.network
3818 [Match]
3819 Name=enp1s0
3820
3821 [Network]
3822 DHCP=ipv6</programlisting>
3823
3824 <programlisting># /etc/systemd/network/56-ipv6-pd-downstream.network
3825 [Match]
3826 Name=enp2s0
3827
3828 [Network]
3829 IPv6SendRA=yes
3830 DHCPv6PrefixDelegation=yes</programlisting>
3831
3832 <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
3833 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
3834 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
3835 </para>
3836 </example>
3837
3838 <example>
3839 <title>A bridge with two enslaved links</title>
3840
3841 <programlisting># /etc/systemd/network/25-bridge-static.network
3842 [Match]
3843 Name=bridge0
3844
3845 [Network]
3846 Address=192.168.0.15/24
3847 Gateway=192.168.0.1
3848 DNS=192.168.0.1</programlisting>
3849
3850 <programlisting># /etc/systemd/network/25-bridge-slave-interface-1.network
3851 [Match]
3852 Name=enp2s0
3853
3854 [Network]
3855 Bridge=bridge0</programlisting>
3856
3857 <programlisting># /etc/systemd/network/25-bridge-slave-interface-2.network
3858 [Match]
3859 Name=wlp3s0
3860
3861 [Network]
3862 Bridge=bridge0</programlisting>
3863
3864 <para>This creates a bridge and attaches devices <literal>enp2s0</literal> and
3865 <literal>wlp3s0</literal> to it. The bridge will have the specified static address
3866 and network assigned, and a default route via the specified gateway will be
3867 added. The specified DNS server will be added to the global list of DNS resolvers.
3868 </para>
3869 </example>
3870
3871 <example>
3872 <title></title>
3873
3874 <programlisting>
3875 # /etc/systemd/network/20-bridge-slave-interface-vlan.network
3876 [Match]
3877 Name=enp2s0
3878
3879 [Network]
3880 Bridge=bridge0
3881
3882 [BridgeVLAN]
3883 VLAN=1-32
3884 PVID=42
3885 EgressUntagged=42
3886
3887 [BridgeVLAN]
3888 VLAN=100-200
3889
3890 [BridgeVLAN]
3891 EgressUntagged=300-400</programlisting>
3892
3893 <para>This overrides the configuration specified in the previous example for the
3894 interface <literal>enp2s0</literal>, and enables VLAN on that bridge port. VLAN IDs
3895 1-32, 42, 100-400 will be allowed. Packets tagged with VLAN IDs 42, 300-400 will be
3896 untagged when they leave on this interface. Untagged packets which arrive on this
3897 interface will be assigned VLAN ID 42.</para>
3898 </example>
3899
3900 <example>
3901 <title>Various tunnels</title>
3902
3903 <programlisting>/etc/systemd/network/25-tunnels.network
3904 [Match]
3905 Name=ens1
3906
3907 [Network]
3908 Tunnel=ipip-tun
3909 Tunnel=sit-tun
3910 Tunnel=gre-tun
3911 Tunnel=vti-tun
3912 </programlisting>
3913
3914 <programlisting>/etc/systemd/network/25-tunnel-ipip.netdev
3915 [NetDev]
3916 Name=ipip-tun
3917 Kind=ipip
3918 </programlisting>
3919
3920 <programlisting>/etc/systemd/network/25-tunnel-sit.netdev
3921 [NetDev]
3922 Name=sit-tun
3923 Kind=sit
3924 </programlisting>
3925
3926 <programlisting>/etc/systemd/network/25-tunnel-gre.netdev
3927 [NetDev]
3928 Name=gre-tun
3929 Kind=gre
3930 </programlisting>
3931
3932 <programlisting>/etc/systemd/network/25-tunnel-vti.netdev
3933 [NetDev]
3934 Name=vti-tun
3935 Kind=vti
3936 </programlisting>
3937
3938 <para>This will bring interface <literal>ens1</literal> up and create an IPIP tunnel,
3939 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.</para>
3940 </example>
3941
3942 <example>
3943 <title>A bond device</title>
3944
3945 <programlisting># /etc/systemd/network/30-bond1.network
3946 [Match]
3947 Name=bond1
3948
3949 [Network]
3950 DHCP=ipv6
3951 </programlisting>
3952
3953 <programlisting># /etc/systemd/network/30-bond1.netdev
3954 [NetDev]
3955 Name=bond1
3956 Kind=bond
3957 </programlisting>
3958
3959 <programlisting># /etc/systemd/network/30-bond1-dev1.network
3960 [Match]
3961 MACAddress=52:54:00:e9:64:41
3962
3963 [Network]
3964 Bond=bond1
3965 </programlisting>
3966
3967 <programlisting># /etc/systemd/network/30-bond1-dev2.network
3968 [Match]
3969 MACAddress=52:54:00:e9:64:42
3970
3971 [Network]
3972 Bond=bond1
3973 </programlisting>
3974
3975 <para>This will create a bond device <literal>bond1</literal> and enslave the two
3976 devices with MAC addresses 52:54:00:e9:64:41 and 52:54:00:e9:64:42 to it. IPv6 DHCP
3977 will be used to acquire an address.</para>
3978 </example>
3979
3980 <example>
3981 <title>Virtual Routing and Forwarding (VRF)</title>
3982 <para>Add the <literal>bond1</literal> interface to the VRF master interface
3983 <literal>vrf1</literal>. This will redirect routes generated on this interface to be
3984 within the routing table defined during VRF creation. For kernels before 4.8 traffic
3985 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
3986 </para>
3987 <programlisting># /etc/systemd/network/25-vrf.network
3988 [Match]
3989 Name=bond1
3990
3991 [Network]
3992 VRF=vrf1
3993 </programlisting>
3994 </example>
3995
3996 <example>
3997 <title>MacVTap</title>
3998 <para>This brings up a network interface <literal>macvtap-test</literal>
3999 and attaches it to <literal>enp0s25</literal>.</para>
4000 <programlisting># /usr/lib/systemd/network/25-macvtap.network
4001 [Match]
4002 Name=enp0s25
4003
4004 [Network]
4005 MACVTAP=macvtap-test
4006 </programlisting>
4007 </example>
4008
4009 <example>
4010 <title>A Xfrm interface with physical underlying device.</title>
4011
4012 <programlisting># /etc/systemd/network/27-xfrm.netdev
4013 [NetDev]
4014 Name=xfrm0
4015
4016 [Xfrm]
4017 InterfaceId=7</programlisting>
4018
4019 <programlisting># /etc/systemd/network/27-eth0.network
4020 [Match]
4021 Name=eth0
4022
4023 [Network]
4024 Xfrm=xfrm0</programlisting>
4025
4026 <para>This creates a <literal>xfrm0</literal> interface and binds it to the <literal>eth0</literal> device.
4027 This allows hardware based ipsec offloading to the <literal>eth0</literal> nic.
4028 If offloading is not needed, xfrm interfaces can be assigned to the <literal>lo</literal> device.
4029 </para>
4030 </example>
4031 </refsect1>
4032
4033 <refsect1>
4034 <title>See Also</title>
4035 <para>
4036 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
4037 <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
4038 <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
4039 <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
4040 <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
4041 </para>
4042 </refsect1>
4043
4044 </refentry>