2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
6 <refentry id=
"systemd.network" conditional='ENABLE_NETWORKD'
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>systemd.network
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>systemd.network
</refentrytitle>
16 <manvolnum>5</manvolnum>
20 <refname>systemd.network
</refname>
21 <refpurpose>Network configuration
</refpurpose>
25 <para><filename><replaceable>network
</replaceable>.network
</filename></para>
29 <title>Description
</title>
31 <para>A plain ini-style text file that encodes network configuration for matching network interfaces,
33 <citerefentry><refentrytitle>systemd-networkd
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
34 See
<citerefentry><refentrytitle>systemd.syntax
</refentrytitle><manvolnum>7</manvolnum></citerefentry>
35 for a general description of the syntax.
</para>
37 <para>The main network file must have the extension
<filename>.network
</filename>; other
38 extensions are ignored. Networks are applied to links whenever the links appear.
</para>
40 <para>The
<filename>.network
</filename> files are read from the files located in the system network
41 directories
<filename>/usr/lib/systemd/network
</filename> and
42 <filename>/usr/local/lib/systemd/network
</filename>, the volatile runtime network directory
43 <filename>/run/systemd/network
</filename> and the local administration network directory
44 <filename>/etc/systemd/network
</filename>. All configuration files are collectively sorted and 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>
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 merged in the alphanumeric order and parsed
55 after the main file itself has been parsed. This is useful to alter or add configuration settings,
56 without having to modify the main configuration file. Each drop-in file must have appropriate
57 section headers.
</para>
59 <para>In addition to
<filename>/etc/systemd/network
</filename>, drop-in
<literal>.d
</literal>
60 directories can be placed in
<filename>/usr/lib/systemd/network
</filename> or
61 <filename>/run/systemd/network
</filename> directories. Drop-in files in
62 <filename>/etc/
</filename> take precedence over those in
<filename>/run/
</filename> which in turn
63 take precedence over those in
<filename>/usr/lib/
</filename>. Drop-in files under any of these
64 directories take precedence over the main network file wherever located.
</para>
68 <title>[Match] Section Options
</title>
70 <para>The network file contains a [Match] section, which determines if a given network file may be
71 applied to a given device; and a [Network] section specifying how the device should be configured. The
72 first (in lexical order) of the network files that matches a given device is applied, all later files
73 are ignored, even if they match as well.
</para>
75 <para>A network file is said to match a network interface if all matches specified by the [Match]
76 section are satisfied. When a network file does not contain valid settings in [Match] section, then the
77 file will match all interfaces and
<command>systemd-networkd
</command> warns about that. Hint: to avoid
78 the warning and to make it clear that all interfaces shall be matched, add the following:
79 <programlisting>Name=*
</programlisting> The following keys are accepted:
</para>
81 <variablelist class='network-directives'
>
82 <xi:include href=
"systemd.link.xml" xpointer=
"mac-address" />
83 <xi:include href=
"systemd.link.xml" xpointer=
"permanent-mac-address" />
84 <xi:include href=
"systemd.link.xml" xpointer=
"path" />
85 <xi:include href=
"systemd.link.xml" xpointer=
"driver" />
86 <xi:include href=
"systemd.link.xml" xpointer=
"type" />
87 <xi:include href=
"systemd.link.xml" xpointer=
"property" />
90 <term><varname>Name=
</varname></term>
92 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
93 by the udev property
<literal>INTERFACE
</literal>, or device's alternative names. If the
94 list is prefixed with a
"!", the test is inverted.
</para>
99 <term><varname>WLANInterfaceType=
</varname></term>
101 <para>A whitespace-separated list of wireless network type. Supported values are
102 <literal>ad-hoc
</literal>,
<literal>station
</literal>,
<literal>ap
</literal>,
103 <literal>ap-vlan
</literal>,
<literal>wds
</literal>,
<literal>monitor
</literal>,
104 <literal>mesh-point
</literal>,
<literal>p2p-client
</literal>,
<literal>p2p-go
</literal>,
105 <literal>p2p-device
</literal>,
<literal>ocb
</literal>, and
<literal>nan
</literal>. If the
106 list is prefixed with a
"!", the test is inverted.
112 <term><varname>SSID=
</varname></term>
114 <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
115 connected wireless LAN. If the list is prefixed with a
"!", the test is inverted.
121 <term><varname>BSSID=
</varname></term>
123 <para>A whitespace-separated list of hardware address of the currently connected wireless
124 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
125 <varname>MACAddress=
</varname>. This option may appear more than once, in which case the
126 lists are merged. If the empty string is assigned to this option, the list is reset.
</para>
130 <xi:include href=
"systemd.link.xml" xpointer=
"host" />
131 <xi:include href=
"systemd.link.xml" xpointer=
"virtualization" />
132 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-command-line" />
133 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-version" />
134 <xi:include href=
"systemd.link.xml" xpointer=
"architecture" />
140 <title>[Link] Section Options
</title>
142 <para> The [Link] section accepts the following keys:
</para>
144 <variablelist class='network-directives'
>
146 <term><varname>MACAddress=
</varname></term>
148 <para>The hardware address to set for the device.
</para>
152 <term><varname>MTUBytes=
</varname></term>
154 <para>The maximum transmission unit in bytes to set for the
155 device. The usual suffixes K, M, G, are supported and are
156 understood to the base of
1024.
</para>
157 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
158 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
162 <term><varname>ARP=
</varname></term>
164 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
165 for this interface is enabled. When unset, the kernel's default will be used.
</para>
166 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
167 interfaces atop a single lower-level physical interface, which will then only serve as a
168 link/
"bridge" device aggregating traffic to the same physical link and not participate in
169 the network otherwise. Defaults to unset.
</para>
173 <term><varname>Multicast=
</varname></term>
175 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults to unset.
</para>
179 <term><varname>AllMulticast=
</varname></term>
181 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the network.
182 This happens when multicast routing is enabled. Defaults to unset.
</para>
186 <term><varname>Promiscuous=
</varname></term>
188 <para>Takes a boolean. If set to true, promiscuous mode of the interface is enabled.
189 Defaults to unset.
</para>
193 <term><varname>Unmanaged=
</varname></term>
195 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are
196 made to bring up or configure matching links, equivalent to
197 when there are no matching network files. Defaults to
198 <literal>no
</literal>.
</para>
199 <para>This is useful for preventing later matching network
200 files from interfering with certain interfaces that are fully
201 controlled by other applications.
</para>
205 <term><varname>Group=
</varname></term>
207 <para>Link groups are similar to port ranges found in managed switches. When network interfaces
208 are added to a numbered group, operations on all the interfaces from that group can be
209 performed at once. Takes an unsigned integer in the range
0…
4294967295. Defaults to unset.
214 <term><varname>RequiredForOnline=
</varname></term>
216 <para>Takes a boolean or a minimum operational state and an optional maximum operational state.
217 Please see
<citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
218 for possible operational states. When
<literal>yes
</literal>, the network is deemed required when
219 determining whether the system is online (including when running
220 <command>systemd-networkd-wait-online
</command>). When
<literal>no
</literal>, the network is ignored
221 when determining the online state. When a minimum operational state and an optional maximum operational
222 state are set,
<literal>yes
</literal> is implied, and this controls the minimum and maximum
223 operational state required for the network interface to be considered online.
</para>
225 <para>Defaults to
<literal>yes
</literal> when
<varname>ActivationPolicy=
</varname> is not set,
226 or set to
<literal>up
</literal>,
<literal>always-up
</literal>, or
<literal>bound
</literal>.
227 Defaults to
<literal>no
</literal> when
<varname>ActivationPolicy=
</varname> is set to
228 <literal>manual
</literal> or
<literal>down
</literal>. This is forced to
<literal>no
</literal>
229 when
<varname>ActivationPolicy=
</varname> is set to
<literal>always-down
</literal>.
</para>
231 <para>The network will be brought up normally (as configured by
<varname>ActivationPolicy=
</varname>),
232 but in the event that there is no address being assigned by DHCP or the
233 cable is not plugged in, the link will simply remain offline and be
234 skipped automatically by
<command>systemd-networkd-wait-online
</command>
235 if
<literal>RequiredForOnline=no
</literal>.
</para>
239 <term><varname>RequiredFamilyForOnline=
</varname></term>
241 <para>Takes an address family. When specified, an IP address in the given family is deemed required
242 when determining whether the link is online (including when running
243 <command>systemd-networkd-wait-online
</command>). Takes one of
<literal>ipv4
</literal>,
244 <literal>ipv6
</literal>,
<literal>both
</literal>, or
<literal>any
</literal>. Defaults to
245 <literal>any
</literal>. Note that this option has no effect if
246 <literal>RequiredForOnline=no
</literal>, or if
<literal>RequiredForOnline=
</literal> specifies a
247 minimum operational state below
<literal>degraded
</literal>.
</para>
251 <term><varname>ActivationPolicy=
</varname></term>
253 <para>Specifies the policy for
<command>systemd-networkd
</command> managing the link
254 administrative state. Specifically, this controls how
<command>systemd-networkd
</command>
255 changes the network device's
<literal>IFF_UP
</literal> flag, which is sometimes
256 controlled by system administrators by running e.g.,
<command>ip set dev eth0 up
</command>
257 or
<command>ip set dev eth0 down
</command>, and can also be changed with
258 <command>networkctl up eth0
</command> or
<command>networkctl down eth0
</command>.
</para>
260 <para>Takes one of
<literal>up
</literal>,
<literal>always-up
</literal>,
261 <literal>manual
</literal>,
<literal>always-down
</literal>,
<literal>down
</literal>,
262 or
<literal>bound
</literal>. When
<literal>manual
</literal>,
<command>systemd-networkd
</command>
263 will not change the link's admin state automatically; the system administrator must bring the
264 interface up or down manually, as desired. When
<literal>up
</literal> (the default) or
265 <literal>always-up
</literal>, or
<literal>down
</literal> or
<literal>always-down
</literal>,
266 <command>systemd-networkd
</command> will set the link up or down, respectively,
267 when the interface is (re)configured. When
<literal>always-up
</literal> or
268 <literal>always-down
</literal>,
<command>systemd-networkd
</command> will set the link up
269 or down, respectively, any time
<command>systemd-networkd
</command> detects a change in
270 the administrative state. When
<varname>BindCarrier=
</varname> is also set, this is
271 automatically set to
<literal>bound
</literal> and any other value is ignored.
</para>
273 <para>When the policy is set to
<literal>down
</literal> or
<literal>manual
</literal>,
274 the default value of
<varname>RequiredForOnline=
</varname> is
<literal>no
</literal>.
275 When the policy is set to
<literal>always-down
</literal>, the value of
276 <varname>RequiredForOnline=
</varname> forced to
<literal>no
</literal>.
</para>
278 <para>The administrative state is not the same as the carrier state, so using
279 <literal>always-up
</literal> does not mean the link will never lose carrier. The link
280 carrier depends on both the administrative state as well as the network device's physical
281 connection. However, to avoid reconfiguration failures, when using
<literal>always-up
</literal>,
282 <varname>IgnoreCarrierLoss=
</varname> is forced to true.
</para>
289 <title>[SR-IOV] Section Options
</title>
290 <para>The [SR-IOV] section accepts the following keys. Specify several [SR-IOV] sections to configure
291 several SR-IOVs. SR-IOV provides the ability to partition a single physical PCI resource into virtual
292 PCI functions which can then be injected into a VM. In the case of network VFs, SR-IOV improves
293 north-south network performance (that is, traffic with endpoints outside the host machine) by allowing
294 traffic to bypass the host machine’s network stack.
</para>
296 <variablelist class='network-directives'
>
298 <term><varname>VirtualFunction=
</varname></term>
300 <para>Specifies a Virtual Function (VF), lightweight PCIe function designed solely to move data
301 in and out. Takes an unsigned integer in the range
0…
2147483646. This option is compulsory.
</para>
306 <term><varname>VLANId=
</varname></term>
308 <para>Specifies VLAN ID of the virtual function. Takes an unsigned integer in the range
1…
4095.
</para>
313 <term><varname>QualityOfService=
</varname></term>
315 <para>Specifies quality of service of the virtual function. Takes an unsigned integer in the range
1…
4294967294.
</para>
320 <term><varname>VLANProtocol=
</varname></term>
322 <para>Specifies VLAN protocol of the virtual function. Takes
<literal>802.1Q
</literal> or
323 <literal>802.1ad
</literal>.
</para>
328 <term><varname>MACSpoofCheck=
</varname></term>
330 <para>Takes a boolean. Controls the MAC spoof checking. When unset, the kernel's default will be used.
</para>
335 <term><varname>QueryReceiveSideScaling=
</varname></term>
337 <para>Takes a boolean. Toggle the ability of querying the receive side scaling (RSS)
338 configuration of the virtual function (VF). The VF RSS information like RSS hash key may be
339 considered sensitive on some devices where this information is shared between VF and the
340 physical function (PF). When unset, the kernel's default will be used.
</para>
345 <term><varname>Trust=
</varname></term>
347 <para>Takes a boolean. Allows to set trust mode of the virtual function (VF). When set, VF
348 users can set a specific feature which may impact security and/or performance. When unset,
349 the kernel's default will be used.
</para>
354 <term><varname>LinkState=
</varname></term>
356 <para>Allows to set the link state of the virtual function (VF). Takes a boolean or a
357 special value
<literal>auto
</literal>. Setting to
<literal>auto
</literal> means a
358 reflection of the physical function (PF) link state,
<literal>yes
</literal> lets the VF to
359 communicate with other VFs on this host even if the PF link state is down,
360 <literal>no
</literal> causes the hardware to drop any packets sent by the VF. When unset,
361 the kernel's default will be used.
</para>
366 <term><varname>MACAddress=
</varname></term>
368 <para>Specifies the MAC address for the virtual function.
</para>
375 <title>[Network] Section Options
</title>
377 <para>The [Network] section accepts the following keys:
</para>
379 <variablelist class='network-directives'
>
381 <term><varname>Description=
</varname></term>
383 <para>A description of the device. This is only used for
384 presentation purposes.
</para>
388 <term><varname>DHCP=
</varname></term>
390 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
391 <literal>yes
</literal>,
<literal>no
</literal>,
392 <literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults
393 to
<literal>no
</literal>.
</para>
395 <para>Note that DHCPv6 will by default be triggered by Router
396 Advertisement, if that is enabled, regardless of this parameter.
397 By enabling DHCPv6 support explicitly, the DHCPv6 client will
398 be started regardless of the presence of routers on the link,
399 or what flags the routers pass. See
400 <literal>IPv6AcceptRA=
</literal>.
</para>
402 <para>Furthermore, note that by default the domain name
403 specified through DHCP is not used for name resolution.
404 See option
<option>UseDomains=
</option> below.
</para>
406 <para>See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the DHCP
407 client support.
</para>
411 <term><varname>DHCPServer=
</varname></term>
413 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started. Defaults
414 to
<literal>no
</literal>. Further settings for the DHCP server may be set in the [DHCPServer]
415 section described below.
</para>
419 <term><varname>LinkLocalAddressing=
</varname></term>
421 <para>Enables link-local address autoconfiguration. Accepts
<option>yes
</option>,
422 <option>no
</option>,
<option>ipv4
</option>, and
<option>ipv6
</option>. An IPv6 link-local address
423 is configured when
<option>yes
</option> or
<option>ipv6
</option>. An IPv4 link-local address is
424 configured when
<option>yes
</option> or
<option>ipv4
</option> and when DHCPv4 autoconfiguration
425 has been unsuccessful for some time. (IPv4 link-local address autoconfiguration will usually
426 happen in parallel with repeated attempts to acquire a DHCPv4 lease).
</para>
428 <para>Defaults to
<option>no
</option> when
<varname>Bridge=yes
</varname> is set, and
429 <option>ipv6
</option> otherwise.
</para>
433 <term><varname>IPv6LinkLocalAddressGenerationMode=
</varname></term>
435 <para>Specifies how IPv6 link local address is generated. Takes one of
436 <literal>eui64
</literal>,
<literal>none
</literal>,
<literal>stable-privacy
</literal> and
437 <literal>random
</literal>. When unset,
<literal>stable-privacy
</literal> is used if
438 <varname>IPv6StableSecretAddress=
</varname> is specified, and if not,
439 <literal>eui64
</literal> is used. Note that if
<varname>LinkLocalAddressing=
</varname> is
440 <literal>no
</literal> or
<literal>ipv4
</literal>, then
441 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> will be ignored. Also, even if
442 <varname>LinkLocalAddressing=
</varname> is
<literal>yes
</literal> or
443 <literal>ipv6
</literal>, setting
<varname>IPv6LinkLocalAddressGenerationMode=none
</varname>
444 disables to configure an IPv6 link-local address.
</para>
448 <term><varname>IPv6StableSecretAddress=
</varname></term>
450 <para>Takes an IPv6 address. The specified address will be used as a stable secret for
451 generating IPv6 link-local address. If this setting is specified, and
452 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> is unset, then
453 <varname>IPv6LinkLocalAddressGenerationMode=stable-privacy
</varname> is implied.
454 If this setting is not specified, and
<literal>stable-privacy
</literal> is set to
455 <varname>IPv6LinkLocalAddressGenerationMode=
</varname>,
456 then a stable secret address will be generated from the local machine ID and the interface
461 <term><varname>IPv4LLRoute=
</varname></term>
463 <para>Takes a boolean. If set to true, sets up the route needed for
464 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
470 <term><varname>DefaultRouteOnDevice=
</varname></term>
472 <para>Takes a boolean. If set to true, sets up the default route bound to the interface.
473 Defaults to false. This is useful when creating routes on point-to-point interfaces.
474 This is equivalent to e.g. the following,
475 <programlisting>ip route add default dev veth99
</programlisting>
477 <programlisting>[Route]
478 Gateway=
0.0.0.0</programlisting></para>
479 <para>Currently, there are no way to specify e.g., the table for the route configured by
480 this setting. To configure the default route with such an additional property, please use
481 the following instead:
482 <programlisting>[Route]
484 Table=
1234</programlisting></para>
488 <term><varname>IPv6Token=
</varname></term>
490 <para>Specifies an optional address generation mode for the Stateless Address
491 Autoconfiguration (SLAAC). Supported modes are
<literal>prefixstable
</literal> and
492 <literal>static
</literal>.
</para>
494 <para>When the mode is set to
<literal>static
</literal>, an IPv6 address must be
495 specified after a colon (
<literal>:
</literal>), and the lower bits of the supplied
496 address are combined with the upper bits of a prefix received in a Router Advertisement
497 (RA) message to form a complete address. Note that if multiple prefixes are received in an
498 RA message, or in multiple RA messages, addresses will be formed from each of them using
499 the supplied address. This mode implements SLAAC but uses a static interface identifier
500 instead of an identifier generated by using the EUI-
64 algorithm. Because the interface
501 identifier is static, if Duplicate Address Detection detects that the computed address is a
502 duplicate (in use by another node on the link), then this mode will fail to provide an
503 address for that prefix. If an IPv6 address without mode is specified, then
504 <literal>static
</literal> mode is assumed.
</para>
506 <para>When the mode is set to
<literal>prefixstable
</literal> the
507 <ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink> algorithm for generating
508 interface identifiers will be used. This mode can optionally take an IPv6 address separated
509 with a colon (
<literal>:
</literal>). If an IPv6 address is specified, then an interface
510 identifier is generated only when a prefix received in an RA message matches the supplied
513 <para>If no address generation mode is specified (which is the default), or a received
514 prefix does not match any of the addresses provided in
<literal>prefixstable
</literal>
515 mode, then the EUI-
64 algorithm will be used to form an interface identifier for that
516 prefix. This mode is also SLAAC, but with a potentially stable interface identifier which
517 does not directly map to the interface's hardware address.
</para>
519 <para>Note that the
<literal>prefixstable
</literal> algorithm uses both the interface
520 name and MAC address as input to the hash to compute the interface identifier, so if either
521 of those are changed the resulting interface identifier (and address) will change, even if
522 the prefix received in the RA message has not changed.
</para>
524 <para>This setting can be specified multiple times. If an empty string is assigned, then
525 the all previous assignments are cleared.
</para>
528 <programlisting>IPv6Token=::
1a:
2b:
3c:
4d
529 IPv6Token=static:::
1a:
2b:
3c:
4d
530 IPv6Token=prefixstable
531 IPv6Token=prefixstable:
2002:da8:
1::
</programlisting></para>
535 <term><varname>LLMNR=
</varname></term>
537 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
539 url=
"https://tools.ietf.org/html/rfc4795">Link-Local
540 Multicast Name Resolution
</ulink> on the link. When set to
541 <literal>resolve
</literal>, only resolution is enabled,
542 but not host registration and announcement. Defaults to
543 true. This setting is read by
544 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
548 <term><varname>MulticastDNS=
</varname></term>
550 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
552 url=
"https://tools.ietf.org/html/rfc6762">Multicast
553 DNS
</ulink> support on the link. When set to
554 <literal>resolve
</literal>, only resolution is enabled,
555 but not host or service registration and
556 announcement. Defaults to false. This setting is read by
557 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
561 <term><varname>DNSOverTLS=
</varname></term>
563 <para>Takes a boolean or
<literal>opportunistic
</literal>.
566 url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink>
568 When set to
<literal>opportunistic
</literal>, compatibility with
569 non-DNS-over-TLS servers is increased, by automatically
570 turning off DNS-over-TLS servers in this case.
571 This option defines a per-interface setting for
572 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
573 global
<varname>DNSOverTLS=
</varname> option. Defaults to
574 false. This setting is read by
575 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
579 <term><varname>DNSSEC=
</varname></term>
581 <para>Takes a boolean or
<literal>allow-downgrade
</literal>. When true, enables
582 <ulink url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink>
583 DNS validation support on the link. When set to
584 <literal>allow-downgrade
</literal>, compatibility with
585 non-DNSSEC capable networks is increased, by automatically
586 turning off DNSSEC in this case. This option defines a
587 per-interface setting for
588 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
589 global
<varname>DNSSEC=
</varname> option. Defaults to
590 false. This setting is read by
591 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
595 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
596 <listitem><para>A space-separated list of DNSSEC negative
597 trust anchor domains. If specified and DNSSEC is enabled,
598 look-ups done via the interface's DNS server will be subject
599 to the list of negative trust anchors, and not require
600 authentication for the specified domains, or anything below
601 it. Use this to disable DNSSEC authentication for specific
602 private domains, that cannot be proven valid using the
603 Internet DNS hierarchy. Defaults to the empty list. This
605 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
609 <term><varname>LLDP=
</varname></term>
611 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
612 implemented on professional routers and bridges which announces which physical port a system is connected
613 to, as well as other related data. Accepts a boolean or the special value
614 <literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
615 neighbors maintained. If
<literal>routers-only
</literal> is set only LLDP data of various types of routers
616 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
617 others). If false, LLDP reception is disabled. Defaults to
<literal>routers-only
</literal>. Use
618 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
619 collected neighbor data. LLDP is only available on Ethernet links. See
<varname>EmitLLDP=
</varname> below
620 for enabling LLDP packet emission from the local system.
625 <term><varname>EmitLLDP=
</varname></term>
627 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
628 <literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
629 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
630 a short LLDP packet with information about the local system is sent out in regular intervals on the
631 link. The LLDP packet will contain information about the local hostname, the local machine ID (as stored
632 in
<citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
633 local interface name, as well as the pretty hostname of the system (as set in
634 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
635 emission is only available on Ethernet links. Note that this setting passes data suitable for
636 identification of host to the network and should thus not be enabled on untrusted networks, where such
637 identification data should not be made available. Use this option to permit other systems to identify on
638 which interfaces they are connected to this system. The three special values control propagation of the
639 LLDP packets. The
<literal>nearest-bridge
</literal> setting permits propagation only to the nearest
640 connected bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays, but
641 not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until a customer bridge
642 is reached. For details about these concepts, see
<ulink
643 url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>. Note that
644 configuring this setting to true is equivalent to
<literal>nearest-bridge
</literal>, the recommended and
645 most restricted level of propagation. See
<varname>LLDP=
</varname> above for an option to enable LLDP
651 <term><varname>BindCarrier=
</varname></term>
653 <para>A link name or a list of link names. When set, controls the behavior of the current
654 link. When all links in the list are in an operational down state, the current link is brought
655 down. When at least one link has carrier, the current interface is brought up.
</para>
657 <para>This forces
<varname>ActivationPolicy=
</varname> to be set to
<literal>bound
</literal>.
</para>
661 <term><varname>Address=
</varname></term>
663 <para>A static IPv4 or IPv6 address and its prefix length,
664 separated by a
<literal>/
</literal> character. Specify
665 this key more than once to configure several addresses.
666 The format of the address must be as described in
667 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
668 This is a short-hand for an [Address] section only
669 containing an Address key (see below). This option may be
670 specified more than once.
673 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
674 (for IPv6), a new address range of the requested size is automatically allocated from a
675 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
676 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
677 all known network configuration files to avoid address range conflicts. The default system-wide
678 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.
679 This functionality is useful to manage a large number of dynamically created network interfaces
680 with the same network configuration and automatic address range assignment.
</para>
685 <term><varname>Gateway=
</varname></term>
687 <para>The gateway address, which must be in the format
689 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
690 This is a short-hand for a [Route] section only containing
691 a Gateway key. This option may be specified more than
696 <term><varname>DNS=
</varname></term>
698 <para>A DNS server address, which must be in the format described in
699 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
700 This option may be specified more than once. Each address can optionally take a port number
701 separated with
<literal>:
</literal>, a network interface name or index separated with
702 <literal>%
</literal>, and a Server Name Indication (SNI) separated with
<literal>#
</literal>.
703 When IPv6 address is specified with a port number, then the address must be in the square
704 brackets. That is, the acceptable full formats are
705 <literal>111.222.333.444:
9953%ifname#example.com
</literal> for IPv4 and
706 <literal>[
1111:
2222::
3333]:
9953%ifname#example.com
</literal> for IPv6. If an empty string is
707 assigned, then the all previous assignments are cleared. This setting is read by
708 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
712 <term><varname>Domains=
</varname></term>
714 <para>A whitespace-separated list of domains which should be resolved using the DNS servers on
715 this link. Each item in the list should be a domain name, optionally prefixed with a tilde
716 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
717 domains without the prefix are called
"search domains" and are first used as search suffixes for
718 extending single-label hostnames (hostnames containing no dots) to become fully qualified
719 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
720 specified search domains are appended to it in turn, converting it into a fully qualified domain
721 name, until one of them may be successfully resolved.
</para>
723 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for hostnames
724 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
725 the DNS servers configured for this interface. The domain routing logic is particularly useful on
726 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
728 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
729 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
730 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
731 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
732 if a link on which they are connected is available.
</para>
734 <para>This setting is read by
735 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
736 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
737 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
738 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
739 name servers limited to a specific link.
</para>
743 <term><varname>DNSDefaultRoute=
</varname></term>
745 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
746 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
747 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
748 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
749 queries not matching any link's configured domains will be routed to this link if it has no routing-only
750 domains configured.
</para>
754 <term><varname>NTP=
</varname></term>
756 <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
757 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
761 <term><varname>IPForward=
</varname></term>
762 <listitem><para>Configures IP packet forwarding for the
763 system. If enabled, incoming packets on any network
764 interface will be forwarded to any other interfaces
765 according to the routing table. Takes a boolean,
766 or the values
<literal>ipv4
</literal> or
767 <literal>ipv6
</literal>, which only enable IP packet
768 forwarding for the specified address family. This controls
769 the
<filename>net.ipv4.ip_forward
</filename> and
770 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
771 options of the network interface (see
<ulink
772 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
773 for details about sysctl options). Defaults to
774 <literal>no
</literal>.
</para>
776 <para>Note: this setting controls a global kernel option,
777 and does so one way only: if a network that has this setting
778 enabled is set up the global setting is turned on. However,
779 it is never turned off again, even after all networks with
780 this setting enabled are shut down again.
</para>
782 <para>To allow IP packet forwarding only between specific
783 network interfaces use a firewall.
</para>
787 <term><varname>IPMasquerade=
</varname></term>
788 <listitem><para>Configures IP masquerading for the network interface. If enabled, packets
789 forwarded from the network interface will be appear as coming from the local host. Takes one
790 of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
<literal>both
</literal>, or
791 <literal>no
</literal>. Defaults to
<literal>no
</literal>. If enabled, this automatically sets
792 <varname>IPForward=
</varname> to one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal> or
793 <literal>yes
</literal>.
</para>
794 <para>Note. Any positive boolean values such as
<literal>yes
</literal> or
795 <literal>true
</literal> are now deprecated. Please use one of the values in the above.
</para>
799 <term><varname>IPv6PrivacyExtensions=
</varname></term>
800 <listitem><para>Configures use of stateless temporary
801 addresses that change over time (see
<ulink
802 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
803 Privacy Extensions for Stateless Address Autoconfiguration
804 in IPv6). Takes a boolean or the special values
805 <literal>prefer-public
</literal> and
806 <literal>kernel
</literal>. When true, enables the privacy
807 extensions and prefers temporary addresses over public
808 addresses. When
<literal>prefer-public
</literal>, enables the
809 privacy extensions, but prefers public addresses over
810 temporary addresses. When false, the privacy extensions
811 remain disabled. When
<literal>kernel
</literal>, the kernel's
812 default setting will be left in place. Defaults to
813 <literal>no
</literal>.
</para></listitem>
816 <term><varname>IPv6AcceptRA=
</varname></term>
817 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
818 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they may
819 trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or if no
820 routers are found on the link. The default is to disable RA reception for bridge devices or when IP
821 forwarding is enabled, and to enable it otherwise. Cannot be enabled on bond devices and when link
822 local addressing is disabled.
</para>
824 <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA] section, see
827 <para>Also see
<ulink
828 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink> in the kernel
829 documentation regarding
<literal>accept_ra
</literal>, but note that systemd's setting of
830 <constant>1</constant> (i.e. true) corresponds to kernel's setting of
<constant>2</constant>.
</para>
832 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
833 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
834 RA protocol is used, and the kernel's own implementation remains disabled, since
835 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
836 and these are not available from the kernel if the kernel's own implementation is used.
</para>
840 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
841 <listitem><para>Configures the amount of IPv6 Duplicate
842 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
846 <term><varname>IPv6HopLimit=
</varname></term>
847 <listitem><para>Configures IPv6 Hop Limit. For each router that
848 forwards the packet, the hop limit is decremented by
1. When the
849 hop limit field reaches zero, the packet is discarded.
850 When unset, the kernel's default will be used.
854 <term><varname>IPv4AcceptLocal=
</varname></term>
855 <listitem><para>Takes a boolean. Accept packets with local source addresses. In combination
856 with suitable routing, this can be used to direct packets between two local interfaces over
857 the wire and have them accepted properly. When unset, the kernel's default will be used.
861 <term><varname>IPv4RouteLocalnet=
</varname></term>
862 <listitem><para>Takes a boolean. When true, the kernel does not consider loopback addresses as martian source or destination
863 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.
867 <term><varname>IPv4ProxyARP=
</varname></term>
868 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
869 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
870 the router accepts responsibility for routing packets to the
"real" destination. See
<ulink
871 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
872 When unset, the kernel's default will be used.
876 <term><varname>IPv6ProxyNDP=
</varname></term>
877 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
878 Protocol) is a technique for IPv6 to allow routing of addresses to a different
879 destination when peers expect them to be present on a certain physical link.
880 In this case a router answers Neighbour Advertisement messages intended for
881 another machine by offering its own MAC address as destination.
882 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
883 Advertisement messages for addresses in the IPv6 neighbor proxy table,
884 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
885 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
886 interface depending on this option.
887 When unset, the kernel's default will be used.
891 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
892 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
893 proxied. This option may be specified more than once. systemd-networkd will add the
894 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
895 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
896 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
900 <term><varname>IPv6SendRA=
</varname></term>
901 <listitem><para>Whether to enable or disable Router Advertisement sending on a link. Takes a
902 boolean value. When enabled, prefixes configured in [IPv6Prefix] sections and routes
903 configured in [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA]
904 section. If
<varname>DHCPv6PrefixDelegation=
</varname> is enabled, then the delegated
905 prefixes are also distributed. See
<varname>DHCPv6PrefixDelegation=
</varname> setting and the
906 [IPv6SendRA], [IPv6Prefix], [IPv6RoutePrefix], and [DHCPv6PrefixDelegation] sections for more
907 configuration options.
</para></listitem>
910 <term><varname>DHCPv6PrefixDelegation=
</varname></term>
911 <listitem><para>Takes a boolean value. When enabled, requests prefixes using a DHCPv6 client
912 configured on another link. By default, an address within each delegated prefix will be
913 assigned, and the prefixes will be announced through IPv6 Router Advertisement when
914 <varname>IPv6SendRA=
</varname> is enabled. Such default settings can be configured in
915 [DHCPv6PrefixDelegation] section. Defaults to disabled.
</para></listitem>
918 <term><varname>IPv6MTUBytes=
</varname></term>
919 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
920 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
924 <term><varname>BatmanAdvanced=
</varname></term>
925 <term><varname>Bond=
</varname></term>
926 <term><varname>Bridge=
</varname></term>
927 <term><varname>VRF=
</varname></term>
929 <para>The name of the B.A.T.M.A.N. Advanced, bond, bridge, or VRF interface to add the link
931 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
936 <term><varname>IPVLAN=
</varname></term>
937 <term><varname>IPVTAP=
</varname></term>
938 <term><varname>L2TP=
</varname></term>
939 <term><varname>MACsec=
</varname></term>
940 <term><varname>MACVLAN=
</varname></term>
941 <term><varname>MACVTAP=
</varname></term>
942 <term><varname>Tunnel=
</varname></term>
943 <term><varname>VLAN=
</varname></term>
944 <term><varname>VXLAN=
</varname></term>
945 <term><varname>Xfrm=
</varname></term>
947 <para>The name of an IPVLAN, IPVTAP, L2TP, MACsec, MACVLAN, MACVTAP, tunnel, VLAN, VXLAN, or
948 Xfrm to be created on the link. See
949 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
950 This option may be specified more than once.
</para>
954 <term><varname>ActiveSlave=
</varname></term>
956 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
957 option is only valid for following modes:
958 <literal>active-backup
</literal>,
959 <literal>balance-alb
</literal> and
960 <literal>balance-tlb
</literal>. Defaults to false.
965 <term><varname>PrimarySlave=
</varname></term>
967 <para>Takes a boolean. Specifies which slave is the primary device. The specified
968 device will always be the active slave while it is available. Only when the
969 primary is off-line will alternate devices be used. This is useful when
970 one slave is preferred over another, e.g. when one slave has higher throughput
971 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
973 <literal>active-backup
</literal>,
974 <literal>balance-alb
</literal> and
975 <literal>balance-tlb
</literal>. Defaults to false.
980 <term><varname>ConfigureWithoutCarrier=
</varname></term>
982 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
983 Defaults to false. If
<option>IgnoreCarrierLoss=
</option> is not explicitly set, it will
984 default to this value.
989 <term><varname>IgnoreCarrierLoss=
</varname></term>
991 <para>Takes a boolean. Allows networkd to retain both the static and dynamic configuration
992 of the interface even if its carrier is lost. When unset, the value specified with
993 <option>ConfigureWithoutCarrier=
</option> is used.
996 <para>When
<varname>ActivationPolicy=
</varname> is set to
<literal>always-up
</literal>, this
997 is forced to
<literal>true
</literal>.
1002 <term><varname>KeepConfiguration=
</varname></term>
1004 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
1005 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
1006 will not drop static addresses and routes on starting up process. When set to
1007 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
1008 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
1009 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
1010 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
1011 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
1012 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
1013 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
<literal>no
</literal>.
1021 <title>[Address] Section Options
</title>
1023 <para>An [Address] section accepts the following keys. Specify several [Address]
1024 sections to configure several addresses.
</para>
1026 <variablelist class='network-directives'
>
1028 <term><varname>Address=
</varname></term>
1030 <para>As in the [Network] section. This key is mandatory. Each [Address] section can contain one
1031 <varname>Address=
</varname> setting.
</para>
1035 <term><varname>Peer=
</varname></term>
1037 <para>The peer address in a point-to-point connection.
1038 Accepts the same format as the
<varname>Address=
</varname>
1043 <term><varname>Broadcast=
</varname></term>
1045 <para>Takes an IPv4 address or boolean value. The address must be in the format described in
1046 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1047 If set to true, then the IPv4 broadcast address will be derived from the
1048 <varname>Address=
</varname> setting. If set to false, then the broadcast address will not
1049 be set. Defaults to true, except for wireguard interfaces, where it default to false.
1054 <term><varname>Label=
</varname></term>
1056 <para>An address label.
</para>
1060 <term><varname>PreferredLifetime=
</varname></term>
1062 <para>Allows the default
"preferred lifetime" of the address to be overridden. Only three
1063 settings are accepted:
<literal>forever
</literal>,
<literal>infinity
</literal>, which is the
1064 default and means that the address never expires, and
<literal>0</literal>, which means that the
1065 address is considered immediately
"expired" and will not be used, unless explicitly requested. A
1066 setting of
<option>PreferredLifetime=
0</option> is useful for addresses which are added to be
1067 used only by a specific application, which is then configured to use them explicitly.
</para>
1071 <term><varname>Scope=
</varname></term>
1073 <para>The scope of the address, which can be
1074 <literal>global
</literal> (valid everywhere on the network, even through a gateway),
1075 <literal>link
</literal> (only valid on this device, will not traverse a gateway) or
1076 <literal>host
</literal> (only valid within the device itself, e.g.
127.0.0.1)
1077 or an unsigned integer in the range
0…
255.
1078 Defaults to
<literal>global
</literal>.
</para>
1082 <term><varname>RouteMetric=
</varname></term>
1084 <para>The metric of the prefix route, which is pointing to the subnet of the configured IP
1085 address, taking the configured prefix length into account. Takes an unsigned integer in the
1086 range
0…
4294967295. When unset or set to
0, the kernel's default value is used. This
1087 setting will be ignored when
<varname>AddPrefixRoute=
</varname> is false.
</para>
1091 <term><varname>HomeAddress=
</varname></term>
1093 <para>Takes a boolean. Designates this address the
"home address" as defined in
1094 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
1095 Supported only on IPv6. Defaults to false.
</para>
1099 <term><varname>DuplicateAddressDetection=
</varname></term>
1101 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
1102 <literal>both
</literal>,
<literal>none
</literal>. When
<literal>ipv4
</literal>,
1103 performs IPv4 Address Conflict Detection. See
1104 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>.
1105 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
1106 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>.
1107 Defaults to
<literal>ipv6
</literal>.
</para>
1111 <term><varname>ManageTemporaryAddress=
</varname></term>
1113 <para>Takes a boolean. If true the kernel manage temporary addresses created
1114 from this one as template on behalf of Privacy Extensions
1115 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
1116 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
1117 The given address needs to have a prefix length of
64. This flag allows using privacy
1118 extensions in a manually configured network, just like if stateless auto-configuration
1119 was active. Defaults to false.
</para>
1123 <term><varname>AddPrefixRoute=
</varname></term>
1125 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
1126 Defaults to true.
</para>
1130 <term><varname>AutoJoin=
</varname></term>
1132 <para>Takes a boolean. Joining multicast group on ethernet level via
1133 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
1134 IGMP snooping since the switch would not replicate multicast packets on ports that did not
1135 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
1136 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
1137 that enables then to do the required join. By extending ip address command with option
1138 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
1139 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
1140 Defaults to
<literal>no
</literal>.
</para>
1147 <title>[Neighbor] Section Options
</title>
1148 <para>A [Neighbor] section accepts the following keys. The neighbor section adds a permanent, static
1149 entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the links
1150 matched for the network. Specify several [Neighbor] sections to configure several static neighbors.
1153 <variablelist class='network-directives'
>
1155 <term><varname>Address=
</varname></term>
1157 <para>The IP address of the neighbor.
</para>
1161 <term><varname>LinkLayerAddress=
</varname></term>
1163 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
1170 <title>[IPv6AddressLabel] Section Options
</title>
1172 <para>An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel]
1173 sections to configure several address labels. IPv6 address labels are used for address selection. See
1174 <ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>. Precedence is managed by userspace,
1175 and only the label itself is stored in the kernel.
</para>
1177 <variablelist class='network-directives'
>
1179 <term><varname>Label=
</varname></term>
1181 <para>The label for the prefix, an unsigned integer in the range
0–
4294967294.
1182 0xffffffff is reserved. This setting is mandatory.
</para>
1186 <term><varname>Prefix=
</varname></term>
1188 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
1189 This key is mandatory.
</para>
1196 <title>[RoutingPolicyRule] Section Options
</title>
1198 <para>An [RoutingPolicyRule] section accepts the following keys. Specify several [RoutingPolicyRule]
1199 sections to configure several rules.
</para>
1201 <variablelist class='network-directives'
>
1203 <term><varname>TypeOfService=
</varname></term>
1205 <para>Takes a number between
0 and
255 that specifies the type of service to match.
</para>
1209 <term><varname>From=
</varname></term>
1211 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1215 <term><varname>To=
</varname></term>
1217 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1221 <term><varname>FirewallMark=
</varname></term>
1223 <para>Specifies the iptables firewall mark value to match (a number between
1 and
1224 4294967295). Optionally, the firewall mask (also a number between
1 and
4294967295) can be
1225 suffixed with a slash (
<literal>/
</literal>), e.g.,
<literal>7/
255</literal>.
</para>
1229 <term><varname>Table=
</varname></term>
1231 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes one of predefined names
1232 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names defined in
<varname>RouteTable=
</varname>
1233 in
<citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1234 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1238 <term><varname>Priority=
</varname></term>
1240 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1241 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1245 <term><varname>IncomingInterface=
</varname></term>
1247 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1251 <term><varname>OutgoingInterface=
</varname></term>
1253 <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>
1257 <term><varname>SourcePort=
</varname></term>
1259 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1260 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1264 <term><varname>DestinationPort=
</varname></term>
1266 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1267 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1271 <term><varname>IPProtocol=
</varname></term>
1273 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1274 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1275 <literal>17</literal> for
<literal>udp
</literal>.
1276 Defaults to unset.
</para>
1280 <term><varname>InvertRule=
</varname></term>
1282 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1286 <term><varname>Family=
</varname></term>
1288 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1289 <literal>both
</literal>. By default, the address family is determined by the address
1290 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1291 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1292 <literal>ipv4
</literal>.
</para>
1296 <term><varname>User=
</varname></term>
1298 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1303 <term><varname>SuppressPrefixLength=
</varname></term>
1305 <para>Takes a number
<replaceable>N
</replaceable> in the range
0…
128 and rejects routing
1306 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1311 <term><varname>Type=
</varname></term>
1313 <para>Specifies Routing Policy Database (RPDB) rule type. Takes one of
<literal>blackhole
</literal>,
1314 <literal>unreachable
</literal> or
<literal>prohibit
</literal>.
1322 <title>[NextHop] Section Options
</title>
1323 <para>The [NextHop] section is used to manipulate entries in the kernel's
"nexthop" tables. The
1324 [NextHop] section accepts the following keys. Specify several [NextHop] sections to configure several
1327 <variablelist class='network-directives'
>
1329 <term><varname>Id=
</varname></term>
1331 <para>The id of the next hop. Takes an unsigned integer in the range
1…
4294967295. If left
1332 unspecified, then automatically chosen by kernel.
</para>
1336 <term><varname>Gateway=
</varname></term>
1338 <para>As in the [Network] section.
</para>
1342 <term><varname>Family=
</varname></term>
1344 <para>Takes one of the special values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>.
1345 By default, the family is determined by the address specified in
1346 <varname>Gateway=
</varname>. If
<varname>Gateway=
</varname> is not specified, then defaults
1347 to
<literal>ipv4
</literal>.
</para>
1351 <term><varname>OnLink=
</varname></term>
1353 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1354 reachable directly by the current machine (i.e., attached to the local network), so that we
1355 can insert the nexthop in the kernel table without it being complained about. Defaults to
1356 <literal>no
</literal>.
</para>
1360 <term><varname>Blackhole=
</varname></term>
1362 <para>Takes a boolean. If enabled, packets to the corresponding routes are discarded
1363 silently, and
<varname>Gateway=
</varname> cannot be specified. Defaults to
1364 <literal>no
</literal>.
</para>
1368 <term><varname>Group=
</varname></term>
1370 <para>Takes a whitespace separated list of nexthop IDs. Each ID must be in the range
1371 1…
4294967295. Optionally, each nexthop ID can take a weight after a colon
1372 (
<literal><replaceable>id
</replaceable><optional>:
<replaceable>weight
</replaceable></optional></literal>).
1373 The weight must be in the range
1…
255. If the weight is not specified, then it is assumed
1374 that the weight is
1. This setting cannot be specified with
<varname>Gateway=
</varname>,
1375 <varname>Family=
</varname>,
<varname>Blackhole=
</varname>. This setting can be specified
1376 multiple times. If an empty string is assigned, then the all previous assignments are
1377 cleared. Defaults to unset.
</para>
1384 <title>[Route] Section Options
</title>
1385 <para>The [Route] section accepts the following keys. Specify several [Route] sections to configure
1386 several routes.
</para>
1388 <variablelist class='network-directives'
>
1390 <term><varname>Gateway=
</varname></term>
1392 <para>Takes the gateway address or the special values
<literal>_dhcp4
</literal> and
1393 <literal>_ipv6ra
</literal>. If
<literal>_dhcp4
</literal> or
<literal>_ipv6ra
</literal> is
1394 set, then the gateway address provided by DHCPv4 or IPv6 RA is used.
</para>
1398 <term><varname>GatewayOnLink=
</varname></term>
1400 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1401 reachable directly by the current machine (i.e., attached to the local network), so that we
1402 can insert the route in the kernel table without it being complained about. Defaults to
1403 <literal>no
</literal>.
</para>
1407 <term><varname>Destination=
</varname></term>
1409 <para>The destination prefix of the route. Possibly
1410 followed by a slash and the prefix length. If omitted, a
1411 full-length host route is assumed.
</para>
1415 <term><varname>Source=
</varname></term>
1417 <para>The source prefix of the route. Possibly followed by
1418 a slash and the prefix length. If omitted, a full-length
1419 host route is assumed.
</para>
1423 <term><varname>Metric=
</varname></term>
1425 <para>The metric of the route. Takes an unsigned integer in the range
0…
4294967295.
1426 Defaults to unset, and the kernel's default will be used.
</para>
1430 <term><varname>IPv6Preference=
</varname></term>
1432 <para>Specifies the route preference as defined in
<ulink
1433 url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink> for Router Discovery messages. Which
1434 can be one of
<literal>low
</literal> the route has a lowest priority,
<literal>medium
</literal>
1435 the route has a default priority or
<literal>high
</literal> the route has a highest priority.
1440 <term><varname>Scope=
</varname></term>
1442 <para>The scope of the IPv4 route, which can be
<literal>global
</literal>,
<literal>site
</literal>,
1443 <literal>link
</literal>,
<literal>host
</literal>, or
1444 <literal>nowhere
</literal>:
</para>
1446 <listitem><para><literal>global
</literal> means the route can reach
1447 hosts more than one hop away.
</para></listitem>
1449 <listitem><para><literal>site
</literal> means an interior route in
1450 the local autonomous system.
</para></listitem>
1452 <listitem><para><literal>link
</literal> means the route can only
1453 reach hosts on the local network (one hop away).
</para></listitem>
1455 <listitem><para><literal>host
</literal> means the route will not
1456 leave the local machine (used for internal addresses like
1457 127.0.0.1).
</para></listitem>
1459 <listitem><para><literal>nowhere
</literal> means the destination
1460 doesn't exist.
</para></listitem>
1462 <para>For IPv4 route, defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
1463 <literal>local
</literal> or
<literal>nat
</literal>,
1464 and
<literal>link
</literal> if
<varname>Type=
</varname> is
1465 <literal>broadcast
</literal>,
<literal>multicast
</literal>, or
<literal>anycast
</literal>.
1466 In other cases, defaults to
<literal>global
</literal>. The value is
1467 not used for IPv6.
</para>
1471 <term><varname>PreferredSource=
</varname></term>
1473 <para>The preferred source address of the route. The address
1474 must be in the format described in
1475 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1479 <term><varname>Table=
</varname></term>
1481 <para>The table identifier for the route. Takes one of predefined names
<literal>default
</literal>,
<literal>main
</literal>,
1482 and
<literal>local
</literal>, and names defined in
<varname>RouteTable=
</varname> in
<citerefentry><refentrytitle>networkd.conf
</refentrytitle>
1483 <manvolnum>5</manvolnum></citerefentry>, or a number between
1 and
4294967295. The table can be retrieved using
1484 <command>ip route show table
<replaceable>num
</replaceable></command>. If unset and
<varname>Type=
</varname> is
<literal>local
</literal>,
1485 <literal>broadcast
</literal>,
<literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1486 In other cases, defaults to
<literal>main
</literal>.
1491 <term><varname>Protocol=
</varname></term>
1493 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1494 <literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1495 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1500 <term><varname>Type=
</varname></term>
1502 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1503 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1504 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1505 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1506 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1507 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1508 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1509 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1510 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1511 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1512 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1517 <term><varname>InitialCongestionWindow=
</varname></term>
1519 <para>The TCP initial congestion window is used during the start of a TCP connection.
1520 During the start of a TCP session, when a client requests a resource, the server's initial
1521 congestion window determines how many packets will be sent during the initial burst of data
1522 without waiting for acknowledgement. Takes a number between
1 and
1023. Note that
100 is
1523 considered an extremely large value for this option. When unset, the kernel's default
1524 (typically
10) will be used.
</para>
1528 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1530 <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
1531 that can initially be buffered at one time on a connection. The sending host can send only
1532 that amount of data before waiting for an acknowledgment and window update from the
1533 receiving host. Takes a number between
1 and
1023. Note that
100 is considered an extremely
1534 large value for this option. When unset, the kernel's default will be used.
</para>
1538 <term><varname>QuickAck=
</varname></term>
1540 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1545 <term><varname>FastOpenNoCookie=
</varname></term>
1547 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1548 When unset, the kernel's default will be used.
1553 <term><varname>TTLPropagate=
</varname></term>
1555 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1556 When unset, the kernel's default will be used.
1561 <term><varname>MTUBytes=
</varname></term>
1563 <para>The maximum transmission unit in bytes to set for the
1564 route. The usual suffixes K, M, G, are supported and are
1565 understood to the base of
1024.
</para>
1566 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1567 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1571 <term><varname>IPServiceType=
</varname></term>
1573 <para>Takes string;
<literal>CS6
</literal> or
<literal>CS4
</literal>. Used to set IP
1574 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.
</para>
1578 <term><varname>TCPAdvertisedMaximumSegmentSize=
</varname></term>
1580 <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G, are
1581 supported and are understood to the base of
1024. An unsigned integer in the range
1–
4294967294.
1582 When unset, the kernel's default will be used.
</para>
1586 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1588 <para>Configures multipath route. Multipath routing is the technique of using multiple
1589 alternative paths through a network. Takes gateway address. Optionally, takes a network
1590 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for
1591 this multipath route separated with whitespace. This setting can be specified multiple
1592 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
1596 <term><varname>NextHop=
</varname></term>
1598 <para>Specifies the nexthop id. Takes an unsigned integer in the range
1…
4294967295.
1599 If set, the corresponding [NextHop] section must be configured. Defaults to unset.
</para>
1606 <title>[DHCPv4] Section Options
</title>
1607 <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
1608 <varname>DHCP=
</varname> setting described above:
</para>
1610 <variablelist class='network-directives'
>
1612 <!-- DHCP packet contents -->
1615 <term><varname>SendHostname=
</varname></term>
1617 <para>When true (the default), the machine's hostname (or the value specified with
1618 <varname>Hostname=
</varname>, described below) will be sent to the DHCP server. Note that the
1619 hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and be
1620 formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option is
1626 <term><varname>Hostname=
</varname></term>
1628 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1629 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1630 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1635 <term><varname>MUDURL=
</varname></term>
1637 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent to the
1638 DHCPv4 server. Takes a URL of length up to
255 characters. A superficial verification that the
1639 string is a valid URL will be performed. DHCPv4 clients are intended to have at most one MUD URL
1640 associated with them. See
<ulink url=
"https://tools.ietf.org/html/rfc8520">RFCÂ
8520</ulink>.
1643 <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers to
1644 advertise device specifications, including the intended communication patterns for their device
1645 when it connects to the network. The network can then use this to author a context-specific
1646 access policy, so the device functions only within those parameters.
</para>
1651 <term><varname>ClientIdentifier=
</varname></term>
1653 <para>The DHCPv4 client identifier to use. Takes one of
<option>mac
</option>,
1654 <option>duid
</option> or
<option>duid-only
</option>. If set to
<option>mac
</option>, the
1655 MAC address of the link is used. If set to
<option>duid
</option>, an RFC4361-compliant Client
1656 ID, which is the combination of IAID and DUID (see below), is used. If set to
1657 <option>duid-only
</option>, only DUID is used, this may not be RFC compliant, but some setups
1658 may require to use this. Defaults to
<option>duid
</option>.
</para>
1663 <term><varname>VendorClassIdentifier=
</varname></term>
1665 <para>The vendor class identifier used to identify vendor
1666 type and configuration.
</para>
1671 <term><varname>UserClass=
</varname></term>
1673 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or
1674 applications it represents. The information contained in this option is a string that represents
1675 the user class of which the client is a member. Each class sets an identifying string of
1676 information to be used by the DHCP service to classify clients. Takes a whitespace-separated list
1682 <term><varname>DUIDType=
</varname></term>
1684 <para>Override the global
<varname>DUIDType=
</varname> setting for this network. See
1685 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1686 for a description of possible values.
</para>
1691 <term><varname>DUIDRawData=
</varname></term>
1693 <para>Override the global
<varname>DUIDRawData=
</varname> setting for this network. See
1694 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1695 for a description of possible values.
</para>
1700 <term><varname>IAID=
</varname></term>
1702 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned
1708 <term><varname>Anonymize=
</varname></term>
1710 <para>Takes a boolean. When true, the options sent to the DHCP server will follow the
1711 <ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink> (Anonymity Profiles for
1712 DHCP Clients) to minimize disclosure of identifying information. Defaults to false.
</para>
1714 <para>This option should only be set to true when
<varname>MACAddressPolicy=
</varname> is
1715 set to
<option>random
</option> (see
1716 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
1719 <para>When true,
<varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1720 <varname>VendorClassIdentifier=
</varname>,
<varname>UserClass=
</varname>,
1721 <varname>RequestOptions=
</varname>,
<varname>SendOption=
</varname>,
1722 <varname>SendVendorOption=
</varname>, and
<varname>MUDURL=
</varname> are ignored.
</para>
1724 <para>With this option enabled DHCP requests will mimic those generated by Microsoft
1725 Windows, in order to reduce the ability to fingerprint and recognize installations. This
1726 means DHCP request sizes will grow and lease data will be more comprehensive than normally,
1727 though most of the requested data is not actually used.
</para>
1732 <term><varname>RequestOptions=
</varname></term>
1734 <para>Sets request options to be sent to the server in the DHCPv4 request options list. A
1735 whitespace-separated list of integers in the range
1…
254. Defaults to unset.
</para>
1740 <term><varname>SendOption=
</varname></term>
1742 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data type
1743 and data separated with a colon
1744 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1745 The option number must be an integer in the range
1…
254. The type takes one of
1746 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
1747 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
1748 string may be escaped using
<ulink
1749 url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1750 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1751 then all options specified earlier are cleared. Defaults to unset.
</para>
1756 <term><varname>SendVendorOption=
</varname></term>
1758 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data
1759 type and data separated with a colon
1760 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1761 The option number must be an integer in the range
1…
254. The type takes one of
1762 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
1763 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
1764 string may be escaped using
<ulink
1765 url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1766 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1767 then all options specified earlier are cleared. Defaults to unset.
</para>
1771 <!-- How to use the DHCP lease -->
1774 <term><varname>UseDNS=
</varname></term>
1776 <para>When true (the default), the DNS servers received from the DHCP server will be used.
</para>
1778 <para>This corresponds to the
<option>nameserver
</option>
1779 option in
<citerefentry
1780 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1785 <term><varname>RoutesToDNS=
</varname></term>
1787 <para>When true, the routes to the DNS servers received from the DHCP server will be
1788 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored.
1789 Defaults to true.
</para>
1794 <term><varname>UseNTP=
</varname></term>
1796 <para>When true (the default), the NTP servers received from the DHCP server will be used by
1797 <filename>systemd-timesyncd.service
</filename>.
</para>
1802 <term><varname>RoutesToNTP=
</varname></term>
1804 <para>When true, the routes to the NTP servers received from the DHCP server will be
1805 configured. When
<varname>UseNTP=
</varname> is disabled, this setting is ignored.
1806 Defaults to true.
</para>
1811 <term><varname>UseSIP=
</varname></term>
1813 <para>When true (the default), the SIP servers received from the DHCP server will be collected
1814 and made available to client programs.
</para>
1819 <term><varname>UseMTU=
</varname></term>
1821 <para>When true, the interface maximum transmission unit from the DHCP server will be used on the
1822 current link. If
<varname>MTUBytes=
</varname> is set, then this setting is ignored. Defaults to
1828 <term><varname>UseHostname=
</varname></term>
1830 <para>When true (the default), the hostname received from the DHCP server will be set as the
1831 transient hostname of the system.
</para>
1836 <term><varname>UseDomains=
</varname></term>
1838 <para>Takes a boolean, or the special value
<option>route
</option>. When true, the domain name
1839 received from the DHCP server will be used as DNS search domain over this link, similar to the
1840 effect of the
<option>Domains=
</option> setting. If set to
<option>route
</option>, the domain
1841 name received from the DHCP server will be used for routing DNS queries only, but not for
1842 searching, similar to the effect of the
<option>Domains=
</option> setting when the argument is
1843 prefixed with
<literal>~
</literal>. Defaults to false.
</para>
1845 <para>It is recommended to enable this option only on trusted networks, as setting this affects
1846 resolution of all hostnames, in particular of single-label names. It is generally safer to use
1847 the supplied domain only as routing domain, rather than as search domain, in order to not have it
1848 affect local resolution of single-label names.
</para>
1850 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
1851 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1857 <term><varname>UseRoutes=
</varname></term>
1859 <para>When true (the default), the static routes will be requested from the DHCP server and added
1860 to the routing table with a metric of
1024, and a scope of
<option>global
</option>,
1861 <option>link
</option> or
<option>host
</option>, depending on the route's destination and
1862 gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the link's own
1863 address, the scope will be set to
<option>host
</option>. Otherwise if the gateway is null (a
1864 direct route), a
<option>link
</option> scope will be used. For anything else, scope defaults to
1865 <option>global
</option>.
</para>
1870 <term><varname>RouteMetric=
</varname></term>
1872 <para>Set the routing metric for routes specified by the DHCP server. Takes an unsigned
1873 integer in the range
0…
4294967295. Defaults to
1024.
</para>
1878 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1880 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1881 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1883 <para>When used in combination with
<varname>VRF=
</varname>, the
1884 VRF's routing table is used when this parameter is not specified.
1890 <term><varname>RouteMTUBytes=
</varname></term>
1892 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.
</para>
1897 <term><varname>UseGateway=
</varname></term>
1899 <para>When true, the gateway will be requested from the DHCP server and added to the routing
1900 table with a metric of
1024, and a scope of
<option>link
</option>. When unset, the value specified
1901 with
<varname>UseRoutes=
</varname> is used.
</para>
1906 <term><varname>UseTimezone=
</varname></term>
1907 <listitem><para>When true, the timezone received from the DHCP server will be set as timezone of
1908 the local system. Defaults to false.
</para></listitem>
1912 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
1914 <para>Allows to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease lifetime.
1915 Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal>. The latter means that the
1916 address never expires. Defaults to unset.
</para>
1920 <!-- How to communicate with the server -->
1923 <term><varname>RequestBroadcast=
</varname></term>
1925 <para>Request the server to use broadcast messages before the IP address has been configured.
1926 This is necessary for devices that cannot receive RAW packets, or that cannot receive packets at
1927 all before an IP address has been configured. On the other hand, this must not be enabled on
1928 networks where broadcasts are filtered out.
</para>
1933 <term><varname>MaxAttempts=
</varname></term>
1935 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1936 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>. Note that the
1937 time between retries is increased exponentially, up to approximately one per minute, so the
1938 network will not be overloaded even if this number is high. The default is suitable in most
1939 circumstances.
</para>
1944 <term><varname>ListenPort=
</varname></term>
1946 <para>Set the port from which the DHCP client packets originate.
</para>
1951 <term><varname>DenyList=
</varname></term>
1953 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are
1954 rejected. Note that if
<varname>AllowList=
</varname> is configured then
1955 <varname>DenyList=
</varname> is ignored.
</para>
1960 <term><varname>AllowList=
</varname></term>
1962 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are
1968 <term><varname>SendRelease=
</varname></term>
1970 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops. Defaults to
1976 <term><varname>SendDecline=
</varname></term>
1978 <para>A boolean. When
<literal>true
</literal>, the DHCPv4 client receives the IP address from the
1979 DHCP server. After a new IP is received, the DHCPv4 client performs IPv4 Duplicate Address
1980 Detection. If duplicate use is detected, the DHCPv4 client rejects the IP by sending a
1981 <constant>DHCPDECLINE
</constant> packet and tries to obtain an IP address again. See
<ulink
1982 url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>. Defaults to
1983 <literal>unset
</literal>.
</para>
1991 <title>[DHCPv6] Section Options
</title>
1992 <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
1993 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
</para>
1995 <variablelist class='network-directives'
>
1997 <!-- DHCP packet contents -->
2000 <term><varname>MUDURL=
</varname></term>
2001 <term><varname>IAID=
</varname></term>
2002 <term><varname>DUIDType=
</varname></term>
2003 <term><varname>DUIDRawData=
</varname></term>
2004 <term><varname>RequestOptions=
</varname></term>
2006 <para>As in the [DHCPv4] section.
</para>
2011 <term><varname>SendOption=
</varname></term>
2013 <para>As in the [DHCPv4] section, however because DHCPv6 uses
16-bit fields to store option
2014 numbers, the option number is an integer in the range
1…
65536.
</para>
2019 <term><varname>SendVendorOption=
</varname></term>
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>:
<replaceable>value
</replaceable></literal>).
2024 Enterprise identifier is an unsigned integer in the range
1…
4294967294. The option number must be
2025 an integer in the range
1…
254. Data type takes one of
<literal>uint8
</literal>,
2026 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
2027 <literal>ipv6address
</literal>, or
<literal>string
</literal>. Special characters in the data
2028 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>
2036 <term><varname>UserClass=
</varname></term>
2038 <para>A DHCPv6 client can use User Class option to identify the type or category of user or
2039 applications it represents. The information contained in this option is a string that represents
2040 the user class of which the client is a member. Each class sets an identifying string of
2041 information to be used by the DHCP service to classify clients. Special characters in the data
2042 string may be escaped using
<ulink
2043 url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2044 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2045 then all options specified earlier are cleared. Takes a whitespace-separated list of
2046 strings. Note that currently
<constant>NUL
</constant> bytes are not allowed.
</para>
2051 <term><varname>VendorClass=
</varname></term>
2053 <para>A DHCPv6 client can use VendorClass option to identify the vendor that manufactured the
2054 hardware on which the client is running. The information contained in the data area of this
2055 option is contained in one or more opaque fields that identify details of the hardware
2056 configuration. Takes a whitespace-separated list of strings.
</para>
2061 <term><varname>PrefixDelegationHint=
</varname></term>
2063 <para>Takes an IPv6 address with prefix length in the same format as the
2064 <varname>Address=
</varname> in the [Network] section. The DHCPv6 client will include a prefix
2065 hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
2066 1–
128. Defaults to unset.
</para>
2070 <!-- How to use the DHCP lease -->
2073 <term><varname>UseAddress=
</varname></term>
2075 <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
2081 <term><varname>UseDNS=
</varname></term>
2082 <term><varname>UseNTP=
</varname></term>
2083 <term><varname>UseHostname=
</varname></term>
2084 <term><varname>UseDomains=
</varname></term>
2086 <para>As in the [DHCPv4] section.
</para>
2090 <!-- How to communicate with the server -->
2093 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
2095 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
2096 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
2097 makes DHCPv6 request network information in a stateless manner using a two-message Information
2098 Request and Information Reply message exchange.
2099 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
2100 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
2101 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
2102 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
2103 By default this option is set to false, enable it if no prefixes are delegated when the device
2104 should be acting as a CE router.
</para>
2109 <term><varname>WithoutRA=
</varname></term>
2111 <para>Allows DHCPv6 client to start without router advertisements's managed or other address
2112 configuration flag. Takes one of
<literal>solicit
</literal> or
2113 <literal>information-request
</literal>. Defaults to unset.
</para>
2118 <term><varname>RapidCommit=
</varname></term>
2120 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
2121 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
2122 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
2123 four-message exchange (solicit, advertise, request, and reply). The two-message exchange provides
2124 faster client configuration and is beneficial in environments in which networks are under a heavy load.
2125 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
2126 Defaults to true.
</para>
2133 <title>[DHCPv6PrefixDelegation] Section Options
</title>
2134 <para>The [DHCPv6PrefixDelegation] section configures delegated prefixes assigned by DHCPv6 server.
2135 The settings in this section are used only when
<varname>DHCPv6PrefixDelegation=
</varname> setting
2138 <variablelist class='network-directives'
>
2140 <term><varname>SubnetId=
</varname></term>
2142 <para>Configure a specific subnet ID on the interface from a (previously) received prefix
2143 delegation. You can either set
"auto" (the default) or a specific subnet ID (as defined in
2144 <ulink url=
"https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC
4291</ulink>, section
2145 2.5.4), in which case the allowed value is hexadecimal, from
0 to
0x7fffffffffffffff
2151 <term><varname>Announce=
</varname></term>
2153 <para>Takes a boolean. When enabled, and
<varname>IPv6SendRA=
</varname> in [Network] section
2154 is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
2155 Defaults to yes.
</para>
2160 <term><varname>Assign=
</varname></term>
2162 <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
2163 are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
2164 interfce), the EUI-
64 algorithm will be used by default to form an interface identifier from
2165 the delegated prefixes. See also
<varname>Token=
</varname> setting below. Defaults to yes.
2171 <term><varname>Token=
</varname></term>
2173 <para>Specifies an optional address generation mode for assigning an address in each
2174 delegated prefix. Takes an IPv6 address. When set, the lower bits of the supplied address is
2175 combined with the upper bits of each delegatad prefix received from the WAN interface by the
2176 DHCPv6 Prefix Delegation to form a complete address. When
<varname>Assign=
</varname> is
2177 disabled, this setting is ignored. When unset, the EUI-
64 algorithm will be used to form
2178 addresses. Defaults to unset.
</para>
2183 <term><varname>ManageTemporaryAddress=
</varname></term>
2185 <para>As in the [Address] section, but defaults to true.
</para>
2190 <term><varname>RouteMetric=
</varname></term>
2192 <para>The metric of the route to the delegated prefix subnet. Takes an unsigned integer in
2193 the range
0…
4294967295. When unset or set to
0, the kernel's default value is used.
</para>
2200 <title>[IPv6AcceptRA] Section Options
</title>
2201 <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
2202 with the
<varname>IPv6AcceptRA=
</varname> setting described above:
</para>
2204 <variablelist class='network-directives'
>
2206 <term><varname>UseDNS=
</varname></term>
2208 <para>When true (the default), the DNS servers received in the Router Advertisement will be used.
</para>
2210 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
2211 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2216 <term><varname>UseDomains=
</varname></term>
2218 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
2219 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
2220 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
2221 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
2222 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
2223 <literal>~
</literal>. Defaults to false.
</para>
2225 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
2226 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
2227 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
2228 single-label names.
</para>
2230 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
2231 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2236 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
2238 <para>The table identifier for the routes received in the Router Advertisement
2239 (a number between
1 and
4294967295, or
0 to unset).
2240 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
2246 <term><varname>RouteMetric=
</varname></term>
2248 <para>Set the routing metric for the routes received in the Router Advertisement. Takes an
2249 unsigned integer in the range
0…
4294967295. Defaults to
1024.
</para>
2254 <term><varname>UseAutonomousPrefix=
</varname></term>
2256 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
2257 precedence over any statically configured ones.
</para>
2262 <term><varname>UseOnLinkPrefix=
</varname></term>
2264 <para>When true (the default), the onlink prefix received in the Router Advertisement will be
2265 used and takes precedence over any statically configured ones.
</para>
2270 <term><varname>RouterDenyList=
</varname></term>
2272 <para>A whitespace-separated list of IPv6 router addresses. Any information advertised by
2273 the listed router is ignored.
</para>
2278 <term><varname>RouterAllowList=
</varname></term>
2280 <para>A whitespace-separated list of IPv6 router addresses. Only information advertised by
2281 the listed router is accepted. Note that if
<varname>RouterAllowList=
</varname> is
2282 configured then
<varname>RouterDenyList=
</varname> is ignored.
</para>
2287 <term><varname>PrefixDenyList=
</varname></term>
2289 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router
2290 advertisements in the list are ignored.
</para>
2295 <term><varname>PrefixAllowList=
</varname></term>
2297 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router
2298 advertisements in the list are allowed. Note that if
<varname>PrefixAllowList=
</varname> is
2299 configured then
<varname>PrefixDenyList=
</varname> is ignored.
</para>
2304 <term><varname>RouteDenyList=
</varname></term>
2306 <para>A whitespace-separated list of IPv6 route prefixes. IPv6 route prefixes supplied via
2307 router advertisements in the list are ignored.
</para>
2312 <term><varname>RouteAllowList=
</varname></term>
2314 <para>A whitespace-separated list of IPv6 route prefixes. IPv6 route prefixes supplied via
2315 router advertisements in the list are allowed. Note that if
<varname>RouteAllowList=
</varname> is
2316 configured then
<varname>RouteDenyList=
</varname> is ignored.
</para>
2321 <term><varname>DHCPv6Client=
</varname></term>
2323 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true or
2324 <literal>always
</literal>, the DHCPv6 client will be started when the RA has the managed or
2325 other information flag. If set to
<literal>always
</literal>, the DHCPv6 client will also be
2326 started in managed mode when neither managed nor other information flag is set in the RA.
2327 Defaults to true.
</para>
2334 <title>[DHCPServer] Section Options
</title>
2335 <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
2336 <varname>DHCPServer=
</varname> option described above:
</para>
2338 <variablelist class='network-directives'
>
2341 <term><varname>ServerAddress=
</varname></term>
2342 <listitem><para>Specifies server address for the DHCP server. Takes an IPv4 address with prefix
2343 length, for example
<literal>192.168.0.1/
24</literal>. This setting may be useful when the link on
2344 which the DHCP server is running has multiple static addresses. When unset, one of static addresses
2345 in the link will be automatically selected. Defaults to unset.
</para></listitem>
2349 <term><varname>PoolOffset=
</varname></term>
2350 <term><varname>PoolSize=
</varname></term>
2352 <listitem><para>Configures the pool of addresses to hand out. The pool
2353 is a contiguous sequence of IP addresses in the subnet configured for
2354 the server address, which does not include the subnet nor the broadcast
2355 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
2356 from the start of subnet, or zero to use the default value.
2357 <varname>PoolSize=
</varname> takes the number of IP addresses in the
2358 pool or zero to use the default value. By default, the pool starts at
2359 the first address after the subnet address and takes up the rest of
2360 the subnet, excluding the broadcast address. If the pool includes
2361 the server address (the default), this is reserved and not handed
2362 out to clients.
</para></listitem>
2366 <term><varname>DefaultLeaseTimeSec=
</varname></term>
2367 <term><varname>MaxLeaseTimeSec=
</varname></term>
2369 <listitem><para>Control the default and maximum DHCP lease
2370 time to pass to clients. These settings take time values in seconds or
2371 another common time unit, depending on the suffix. The default
2372 lease time is used for clients that did not ask for a specific
2373 lease time. If a client asks for a lease time longer than the
2374 maximum lease time, it is automatically shortened to the
2375 specified time. The default lease time defaults to
1h, the
2376 maximum lease time to
12h. Shorter lease times are beneficial
2377 if the configuration data in DHCP leases changes frequently
2378 and clients shall learn the new settings with shorter
2379 latencies. Longer lease times reduce the generated DHCP
2380 network traffic.
</para></listitem>
2384 <term><varname>UplinkInterface=
</varname></term>
2385 <listitem><para>Specifies name or index of uplink interface, or one of the special values
2386 <literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS, NTP, or SIP servers
2387 are enabled but no servers are specified, the servers configured in the uplink interface will
2388 be emitted. When
<literal>:auto
</literal>, the link which has default gateway with higher
2389 priority will be automatically selected. When
<literal>:none
</literal>, no uplink interface
2390 will be selected. Defaults to
<literal>:auto
</literal>.
</para></listitem>
2394 <term><varname>EmitDNS=
</varname></term>
2395 <term><varname>DNS=
</varname></term>
2397 <listitem><para><varname>EmitDNS=
</varname> takes a boolean. Configures whether the DHCP leases
2398 handed out to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>. The
2399 DNS servers to pass to clients may be configured with the
<varname>DNS=
</varname> option, which takes
2400 a list of IPv4 addresses. If the
<varname>EmitDNS=
</varname> option is enabled but no servers
2401 configured, the servers are automatically propagated from an
"uplink" interface that has appropriate
2402 servers set. The
"uplink" interface is determined by the default route of the system with the highest
2403 priority. Note that this information is acquired at the time the lease is handed out, and does not
2404 take uplink interfaces into account that acquire DNS server information at a later point. If no
2405 suitable uplink interface is found the DNS server data from
<filename>/etc/resolv.conf
</filename> is
2406 used. Also, note that the leases are not refreshed if the uplink network configuration changes. To
2407 ensure clients regularly acquire the most current uplink DNS server information, it is thus advisable
2408 to shorten the DHCP lease time via
<varname>MaxLeaseTimeSec=
</varname> described
2409 above.
</para></listitem>
2413 <term><varname>EmitNTP=
</varname></term>
2414 <term><varname>NTP=
</varname></term>
2415 <term><varname>EmitSIP=
</varname></term>
2416 <term><varname>SIP=
</varname></term>
2417 <term><varname>EmitPOP3=
</varname></term>
2418 <term><varname>POP3=
</varname></term>
2419 <term><varname>EmitSMTP=
</varname></term>
2420 <term><varname>SMTP=
</varname></term>
2421 <term><varname>EmitLPR=
</varname></term>
2422 <term><varname>LPR=
</varname></term>
2424 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname> settings
2425 described above, these settings configure whether and what server information for the indicate
2426 protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
2427 defaults apply as for
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname>.
</para></listitem>
2431 <term><varname>EmitRouter=
</varname></term>
2433 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
2434 setting described above, this setting configures whether the
2435 DHCP lease should contain the router option. The same syntax,
2436 propagation semantics and defaults apply as for
2437 <varname>EmitDNS=
</varname>.
</para></listitem>
2441 <term><varname>EmitTimezone=
</varname></term>
2442 <term><varname>Timezone=
</varname></term>
2444 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
2445 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
2446 <varname>Timezone=
</varname> setting takes a timezone string
2447 (such as
<literal>Europe/Berlin
</literal> or
2448 <literal>UTC
</literal>) to pass to clients. If no explicit
2449 timezone is set, the system timezone of the local host is
2450 propagated, as determined by the
2451 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
2455 <term><varname>SendOption=
</varname></term>
2457 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
2458 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2459 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
2460 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
2461 <literal>string
</literal>. Special characters in the data string may be escaped using
2462 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2463 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2464 then all options specified earlier are cleared. Defaults to unset.
</para>
2469 <term><varname>SendVendorOption=
</varname></term>
2471 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
2472 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2473 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
2474 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
2475 <literal>string
</literal>. Special characters in the data string may be escaped using
2476 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2477 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2478 then all options specified earlier are cleared. Defaults to unset.
</para>
2482 <term><varname>BindToInterface=
</varname></term>
2484 <para>Takes a boolean value. When
<literal>yes
</literal>, DHCP server socket will be bound
2485 to its network interface and all socket communication will be restricted to this interface.
2486 Defaults to
<literal>yes
</literal>, except if
<varname>RelayTarget=
</varname> is used (see below),
2487 in which case it defaults defaults to
<literal>no
</literal>.
</para>
2491 <term><varname>RelayTarget=
</varname></term>
2493 <para>Takes an IPv4 address, which must be in the format described in
2494 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
2495 Turns this DHCP server into a DHCP relay agent. See
<ulink url=
"https://tools.ietf.org/html/rfc1542">RFC
1542</ulink>.
2496 The address is the address of DHCP server or another relay agent to forward DHCP messages to and from.
</para>
2500 <term><varname>RelayAgentCircuitId=
</varname></term>
2502 <para>Specifies value for Agent Circuit ID suboption of Relay Agent Information option.
2503 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
2504 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
2505 Defaults to unset (means no Agent Circuit ID suboption is generated).
2506 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
2510 <term><varname>RelayAgentRemoteId=
</varname></term>
2512 <para>Specifies value for Agent Remote ID suboption of Relay Agent Information option.
2513 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
2514 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
2515 Defaults to unset (means no Agent Remote ID suboption is generated).
2516 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
2524 <title>[DHCPServerStaticLease] Section Options
</title>
2525 <para>The
<literal>[DHCPServerStaticLease]
</literal> section configures a static DHCP lease to assign a
2526 fixed IPv4 address to a specific device based on its MAC address. This section can be specified multiple
2529 <variablelist class='network-directives'
>
2531 <term><varname>MACAddress=
</varname></term>
2533 <listitem><para>The hardware address of a device to match. This key is mandatory.
</para></listitem>
2537 <term><varname>Address=
</varname></term>
2539 <listitem><para>The IPv4 address that should be assigned to the device that was matched with
2540 <varname>MACAddress=
</varname>. This key is mandatory.
</para></listitem>
2546 <title>[IPv6SendRA] Section Options
</title>
2547 <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
2548 to act as a router, if enabled via the
<varname>IPv6SendRA=
</varname> option described above. IPv6
2549 network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
2552 <variablelist class='network-directives'
>
2555 <term><varname>Managed=
</varname></term>
2556 <term><varname>OtherInformation=
</varname></term>
2558 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
2559 addresses on the network link when
<varname>Managed=
</varname>
2560 is set to
<literal>true
</literal> or if only additional network
2561 information can be obtained via DHCPv6 for the network link when
2562 <varname>OtherInformation=
</varname> is set to
2563 <literal>true
</literal>. Both settings default to
2564 <literal>false
</literal>, which means that a DHCPv6 server is not being
2565 used.
</para></listitem>
2569 <term><varname>RouterLifetimeSec=
</varname></term>
2571 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. When set to
2572 0, the host is not acting as a router. Defaults to
30 minutes.
</para>
2577 <term><varname>RouterPreference=
</varname></term>
2579 <listitem><para>Configures IPv6 router preference if
2580 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
2581 <literal>high
</literal>,
<literal>medium
</literal> and
2582 <literal>low
</literal>, with
<literal>normal
</literal> and
2583 <literal>default
</literal> added as synonyms for
2584 <literal>medium
</literal> just to make configuration easier. See
2585 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2586 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
2590 <term><varname>EmitDNS=
</varname></term>
2591 <term><varname>DNS=
</varname></term>
2593 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses that
2594 are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is
2595 true.
<varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that case
2596 the IPv6 link local address is distributed. If
<varname>DNS=
</varname> is empty, DNS servers are read
2597 from the [Network] section. If the [Network] section does not contain any DNS servers either, DNS
2598 servers from the uplink with the highest priority default route are used. When
2599 <varname>EmitDNS=
</varname> is false, no DNS server information is sent in Router Advertisement
2600 messages.
<varname>EmitDNS=
</varname> defaults to true.
</para></listitem>
2604 <term><varname>EmitDomains=
</varname></term>
2605 <term><varname>Domains=
</varname></term>
2607 <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
2608 <varname>EmitDomains=
</varname> is true. If
<varname>Domains=
</varname> is empty, DNS search domains
2609 are read from the [Network] section. If the [Network] section does not contain any DNS search domains
2610 either, DNS search domains from the uplink with the highest priority default route are used. When
2611 <varname>EmitDomains=
</varname> is false, no DNS search domain information is sent in Router
2612 Advertisement messages.
<varname>EmitDomains=
</varname> defaults to true.
</para></listitem>
2616 <term><varname>DNSLifetimeSec=
</varname></term>
2618 <listitem><para>Lifetime in seconds for the DNS server addresses listed
2619 in
<varname>DNS=
</varname> and search domains listed in
2620 <varname>Domains=
</varname>.
</para></listitem>
2627 <title>[IPv6Prefix] Section Options
</title>
2628 <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
2629 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink> for further
2632 <variablelist class='network-directives'
>
2635 <term><varname>AddressAutoconfiguration=
</varname></term>
2636 <term><varname>OnLink=
</varname></term>
2638 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
2639 autoconfigured with this prefix and whether the prefix can be used for
2640 onlink determination. Both settings default to
<literal>true
</literal>
2641 in order to ease configuration.
2646 <term><varname>Prefix=
</varname></term>
2648 <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
2649 IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
2650 <literal>/
</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
2651 prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
2652 prefix to another.
</para></listitem>
2656 <term><varname>PreferredLifetimeSec=
</varname></term>
2657 <term><varname>ValidLifetimeSec=
</varname></term>
2659 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2660 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
2661 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
2662 to
2592000 seconds (
30 days).
</para></listitem>
2666 <term><varname>Assign=
</varname></term>
2667 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
2672 <term><varname>RouteMetric=
</varname></term>
2674 <para>The metric of the prefix route. Takes an unsigned integer in the range
0…
4294967295.
2675 When unset or set to
0, the kernel's default value is used. This setting is ignored when
2676 <varname>Assign=
</varname> is false.
</para>
2683 <title>[IPv6RoutePrefix] Section Options
</title>
2684 <para>One or more [IPv6RoutePrefix] sections contain the IPv6
2685 prefix routes that are announced via Router Advertisements. See
2686 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2687 for further details.
</para>
2689 <variablelist class='network-directives'
>
2692 <term><varname>Route=
</varname></term>
2694 <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
2695 IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
2696 separated by a
<literal>/
</literal> character. Use multiple [IPv6PrefixRoutes] sections to configure
2697 multiple IPv6 prefix routes.
</para></listitem>
2701 <term><varname>LifetimeSec=
</varname></term>
2703 <listitem><para>Lifetime for the route prefix measured in
2704 seconds.
<varname>LifetimeSec=
</varname> defaults to
604800 seconds (one week).
2712 <title>[Bridge] Section Options
</title>
2713 <para>The [Bridge] section accepts the following keys:
</para>
2714 <variablelist class='network-directives'
>
2716 <term><varname>UnicastFlood=
</varname></term>
2718 <para>Takes a boolean. Controls whether the bridge should flood
2719 traffic for which an FDB entry is missing and the destination
2720 is unknown through this port. When unset, the kernel's default will be used.
2725 <term><varname>MulticastFlood=
</varname></term>
2727 <para>Takes a boolean. Controls whether the bridge should flood
2728 traffic for which an MDB entry is missing and the destination
2729 is unknown through this port. When unset, the kernel's default will be used.
2734 <term><varname>MulticastToUnicast=
</varname></term>
2736 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2737 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2738 When unset, the kernel's default will be used.
2743 <term><varname>NeighborSuppression=
</varname></term>
2745 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2746 this port. When unset, the kernel's default will be used.
2751 <term><varname>Learning=
</varname></term>
2753 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2754 this port. When unset, the kernel's default will be used.
2759 <term><varname>HairPin=
</varname></term>
2761 <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
2762 was received. When this flag is false, then the bridge will not forward traffic back out of the
2763 receiving port. When unset, the kernel's default will be used.
</para>
2767 <term><varname>UseBPDU=
</varname></term>
2769 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2770 processed by the bridge port. When unset, the kernel's default will be used.
</para>
2774 <term><varname>FastLeave=
</varname></term>
2776 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2777 traffic on a port that receives an IGMP Leave message. It is only used with
2778 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
2782 <term><varname>AllowPortToBeRoot=
</varname></term>
2784 <para>Takes a boolean. Configures whether a given port is allowed to
2785 become a root port. Only used when STP is enabled on the bridge.
2786 When unset, the kernel's default will be used.
</para>
2790 <term><varname>ProxyARP=
</varname></term>
2792 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2793 When unset, the kernel's default will be used.
</para>
2797 <term><varname>ProxyARPWiFi=
</varname></term>
2799 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2800 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
2801 When unset, the kernel's default will be used.
</para>
2805 <term><varname>MulticastRouter=
</varname></term>
2807 <para>Configures this port for having multicast routers attached. A port with a multicast
2808 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
2809 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
2810 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
2811 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
2812 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
2816 <term><varname>Cost=
</varname></term>
2818 <para>Sets the
"cost" of sending packets of this interface.
2819 Each port in a bridge may have a different speed and the cost
2820 is used to decide which link to use. Faster interfaces
2821 should have lower costs. It is an integer value between
1 and
2826 <term><varname>Priority=
</varname></term>
2828 <para>Sets the
"priority" of sending packets on this interface.
2829 Each port in a bridge may have a different priority which is used
2830 to decide which link to use. Lower value means higher priority.
2831 It is an integer value between
0 to
63. Networkd does not set any
2832 default, meaning the kernel default value of
32 is used.
</para>
2838 <title>[BridgeFDB] Section Options
</title>
2839 <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
2840 keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.
</para>
2842 <variablelist class='network-directives'
>
2844 <term><varname>MACAddress=
</varname></term>
2846 <para>As in the [Network] section. This key is mandatory.
</para>
2850 <term><varname>Destination=
</varname></term>
2852 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
2856 <term><varname>VLANId=
</varname></term>
2858 <para>The VLAN ID for the new static MAC table entry. If
2859 omitted, no VLAN ID information is appended to the new static MAC
2864 <term><varname>VNI=
</varname></term>
2866 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2867 the remote VXLAN tunnel endpoint. Takes a number in the range
1…
16777215.
2868 Defaults to unset.
</para>
2872 <term><varname>AssociatedWith=
</varname></term>
2874 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
2875 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
2876 <literal>use
</literal> means the address is in use. User space can use this option to
2877 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
2878 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
2879 means the address is associated with master devices fdb.
<literal>router
</literal> means
2880 the destination address is associated with a router. Note that it's valid if the referenced
2881 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
2885 <term><varname>OutgoingInterface=
</varname></term>
2887 <para>Specifies the name or index of the outgoing interface for the VXLAN device driver to
2888 reach the remote VXLAN tunnel endpoint. Defaults to unset.
</para>
2894 <title>[BridgeMDB] Section Options
</title>
2895 <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
2896 keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.
</para>
2898 <variablelist class='network-directives'
>
2900 <term><varname>MulticastGroupAddress=
</varname></term>
2902 <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.
</para>
2906 <term><varname>VLANId=
</varname></term>
2908 <para>The VLAN ID for the new entry. Valid ranges are
0 (no VLAN) to
4094. Optional, defaults to
0.
</para>
2915 <title>[LLDP] Section Options
</title>
2916 <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
2918 <variablelist class='network-directives'
>
2920 <term><varname>MUDURL=
</varname></term>
2922 <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
2923 LLDP packets. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
2924 [DHCPv4] section described above.
</para>
2926 <para>The MUD URLs received via LLDP packets are saved and can be read using the
2927 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
2934 <title>[CAN] Section Options
</title>
2935 <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
2936 following keys:
</para>
2937 <variablelist class='network-directives'
>
2939 <term><varname>BitRate=
</varname></term>
2941 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
2942 be used here. Takes a number in the range
1…
4294967295.
</para>
2946 <term><varname>SamplePoint=
</varname></term>
2948 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2949 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2953 <term><varname>DataBitRate=
</varname></term>
2954 <term><varname>DataSamplePoint=
</varname></term>
2956 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
2957 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
2961 <term><varname>FDMode=
</varname></term>
2963 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
2964 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
2965 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys.
</para>
2969 <term><varname>FDNonISO=
</varname></term>
2971 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
2972 interface. When unset, the kernel's default will be used.
</para>
2976 <term><varname>RestartSec=
</varname></term>
2978 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2979 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2980 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2981 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2982 automatic restart off. By default automatic restart is disabled.
</para>
2986 <term><varname>Termination=
</varname></term>
2988 <para>Takes a boolean. When
<literal>yes
</literal>, the termination resistor will be selected for
2989 the bias network. When unset, the kernel's default will be used.
</para>
2993 <term><varname>TripleSampling=
</varname></term>
2995 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2996 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
3000 <term><varname>BusErrorReporting=
</varname></term>
3002 <para>Takes a boolean. When
<literal>yes
</literal>, reporting of CAN bus errors is activated
3003 (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
3004 unable to send recessive bit, bus overload, active error announcement, error occurred on
3005 transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
3006 single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.
</para>
3010 <term><varname>ListenOnly=
</varname></term>
3012 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
3013 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
3014 bit. Listen-only mode is important to debug CAN networks without interfering with the
3015 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
3023 <title>[QDisc] Section Options
</title>
3024 <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).
</para>
3026 <variablelist class='network-directives'
>
3028 <term><varname>Parent=
</varname></term>
3030 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
3031 or
<literal>ingress
</literal>. This is mandatory.
</para>
3035 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3040 <title>[NetworkEmulator] Section Options
</title>
3041 <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
3042 can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
3043 applications, or limit the bandwidth usage of a particular service to simulate internet connections.
3046 <variablelist class='network-directives'
>
3047 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3048 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3051 <term><varname>DelaySec=
</varname></term>
3053 <para>Specifies the fixed amount of delay to be added to all packets going out of the
3054 interface. Defaults to unset.
</para>
3059 <term><varname>DelayJitterSec=
</varname></term>
3061 <para>Specifies the chosen delay to be added to the packets outgoing to the network
3062 interface. Defaults to unset.
</para>
3067 <term><varname>PacketLimit=
</varname></term>
3069 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
3070 An unsigned integer in the range
0–
4294967294. Defaults to
1000.
</para>
3075 <term><varname>LossRate=
</varname></term>
3077 <para>Specifies an independent loss probability to be added to the packets outgoing from the
3078 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
3083 <term><varname>DuplicateRate=
</varname></term>
3085 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
3086 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
3093 <title>[TokenBucketFilter] Section Options
</title>
3094 <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
3097 <variablelist class='network-directives'
>
3098 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3099 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3102 <term><varname>LatencySec=
</varname></term>
3104 <para>Specifies the latency parameter, which specifies the maximum amount of time a
3105 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
3110 <term><varname>LimitBytes=
</varname></term>
3112 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
3113 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
3114 respectively, to the base of
1024. Defaults to unset.
</para>
3119 <term><varname>BurstBytes=
</varname></term>
3121 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
3122 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
3123 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to
3129 <term><varname>Rate=
</varname></term>
3131 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
3132 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
3133 Defaults to unset.
</para>
3138 <term><varname>MPUBytes=
</varname></term>
3140 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
3141 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3142 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to zero.
</para>
3147 <term><varname>PeakRate=
</varname></term>
3149 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
3150 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
3151 1000. Defaults to unset.
</para>
3156 <term><varname>MTUBytes=
</varname></term>
3158 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
3159 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
3160 Defaults to unset.
</para>
3167 <title>[PIE] Section Options
</title>
3168 <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
3169 controller-Enhanced (PIE).
</para>
3171 <variablelist class='network-directives'
>
3172 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3173 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3176 <term><varname>PacketLimit=
</varname></term>
3178 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3179 incoming packets are dropped. An unsigned integer in the range
1…
4294967294. Defaults to unset and
3180 kernel's default is used.
</para>
3187 <title>[FlowQueuePIE] Section Options
</title>
3188 <para>The
<literal>[FlowQueuePIE]
</literal> section manages the queueing discipline
3189 (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).
</para>
3191 <variablelist class='network-directives'
>
3192 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3193 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3196 <term><varname>PacketLimit=
</varname></term>
3198 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3199 incoming packets are dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and
3200 kernel's default is used.
</para>
3207 <title>[StochasticFairBlue] Section Options
</title>
3208 <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
3211 <variablelist class='network-directives'
>
3212 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3213 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3216 <term><varname>PacketLimit=
</varname></term>
3218 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3219 incoming packets are dropped. An unsigned integer in the range
0–
4294967294. Defaults to unset and
3220 kernel's default is used.
</para>
3227 <title>[StochasticFairnessQueueing] Section Options
</title>
3228 <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
3229 fairness queueing (sfq).
</para>
3231 <variablelist class='network-directives'
>
3232 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3233 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3236 <term><varname>PerturbPeriodSec=
</varname></term>
3238 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
3245 <title>[BFIFO] Section Options
</title>
3246 <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
3249 <variablelist class='network-directives'
>
3250 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3251 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3254 <term><varname>LimitBytes=
</varname></term>
3256 <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
3257 in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
3258 reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
3259 as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
3260 kernel default is used.
</para>
3267 <title>[PFIFO] Section Options
</title>
3268 <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
3271 <variablelist class='network-directives'
>
3272 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3273 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3276 <term><varname>PacketLimit=
</varname></term>
3278 <para>Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents
3279 overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this
3280 limit is reached, incoming packets are dropped. An unsigned integer in the range
3281 0–
4294967294. Defaults to unset and kernel's default is used.
</para>
3288 <title>[PFIFOHeadDrop] Section Options
</title>
3289 <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
3290 Head Drop (pfifo_head_drop).
</para>
3292 <variablelist class='network-directives'
>
3293 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3294 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3297 <term><varname>PacketLimit=
</varname></term>
3299 <para>As in [PFIFO] section.
</para></listitem>
3305 <title>[PFIFOFast] Section Options
</title>
3306 <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
3307 (pfifo_fast).
</para>
3309 <variablelist class='network-directives'
>
3310 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3311 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3316 <title>[CAKE] Section Options
</title>
3317 <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
3320 <variablelist class='network-directives'
>
3321 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3322 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3325 <term><varname>OverheadBytes=
</varname></term>
3327 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative. Takes
3328 an integer in the range from -
64 to
256. Defaults to unset and kernel's default is used.
</para>
3333 <term><varname>Bandwidth=
</varname></term>
3335 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
3336 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
3337 unset and kernel's default is used.
</para>
3344 <title>[ControlledDelay] Section Options
</title>
3345 <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
3346 controlled delay (CoDel).
</para>
3348 <variablelist class='network-directives'
>
3349 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3350 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3353 <term><varname>PacketLimit=
</varname></term>
3355 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3356 incoming packets are dropped. An unsigned integer in the range
0–
4294967294. Defaults to unset and
3357 kernel's default is used.
</para>
3362 <term><varname>TargetSec=
</varname></term>
3364 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
3365 Defaults to unset and kernel's default is used.
</para>
3370 <term><varname>IntervalSec=
</varname></term>
3372 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
3373 become too stale. Defaults to unset and kernel's default is used.
</para>
3378 <term><varname>ECN=
</varname></term>
3380 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3381 unset and kernel's default is used.
</para>
3386 <term><varname>CEThresholdSec=
</varname></term>
3388 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3389 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3396 <title>[DeficitRoundRobinScheduler] Section Options
</title>
3397 <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
3398 Robin Scheduler (DRR).
</para>
3400 <variablelist class='network-directives'
>
3401 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3402 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3407 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
3408 <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
3409 Robin Scheduler (DRR).
</para>
3411 <variablelist class='network-directives'
>
3412 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3413 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3416 <term><varname>QuantumBytes=
</varname></term>
3418 <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
3419 to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3420 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to the MTU of the
3429 <title>[EnhancedTransmissionSelection] Section Options
</title>
3430 <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
3431 Transmission Selection (ETS).
</para>
3433 <variablelist class='network-directives'
>
3434 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3435 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3438 <term><varname>Bands=
</varname></term>
3440 <para>Specifies the number of bands. An unsigned integer in the range
1–
16. This value has to be at
3441 least large enough to cover the strict bands specified through the
<varname>StrictBands=
</varname>
3442 and bandwidth-sharing bands specified in
<varname>QuantumBytes=
</varname>.
</para>
3447 <term><varname>StrictBands=
</varname></term>
3449 <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
3450 the range
1–
16.
</para>
3455 <term><varname>QuantumBytes=
</varname></term>
3457 <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
3458 suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3459 respectively, to the base of
1024. This setting can be specified multiple times. If an empty
3460 string is assigned, then the all previous assignments are cleared.
</para>
3465 <term><varname>PriorityMap=
</varname></term>
3467 <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
3468 separated list of numbers. The first number indicates which band the packets with priority
0 should
3469 be put to, the second is for priority
1, and so on. There can be up to
16 numbers in the list. If
3470 there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
3471 the last one. Each band number must be in the range
0…
255. This setting can be specified multiple
3472 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
3479 <title>[GenericRandomEarlyDetection] Section Options
</title>
3480 <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
3481 Early Detection (GRED).
</para>
3483 <variablelist class='network-directives'
>
3484 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3485 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3488 <term><varname>VirtualQueues=
</varname></term>
3490 <para>Specifies the number of virtual queues. Takes an integer in the range
1…
16. Defaults to unset
3491 and kernel's default is used.
</para>
3496 <term><varname>DefaultVirtualQueue=
</varname></term>
3498 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
3499 Defaults to unset and kernel's default is used.
</para>
3504 <term><varname>GenericRIO=
</varname></term>
3506 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
3507 unset and kernel's default is used.
</para>
3514 <title>[FairQueueingControlledDelay] Section Options
</title>
3515 <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
3516 controlled delay (FQ-CoDel).
</para>
3518 <variablelist class='network-directives'
>
3519 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3520 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3523 <term><varname>PacketLimit=
</varname></term>
3525 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3526 dropped. Defaults to unset and kernel's default is used.
</para>
3531 <term><varname>MemoryLimitBytes=
</varname></term>
3533 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
3534 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3535 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
3540 <term><varname>Flows=
</varname></term>
3542 <para>Specifies the number of flows into which the incoming packets are classified.
3543 Defaults to unset and kernel's default is used.
</para>
3548 <term><varname>TargetSec=
</varname></term>
3550 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
3551 Defaults to unset and kernel's default is used.
</para>
3556 <term><varname>IntervalSec=
</varname></term>
3558 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
3559 become too stale. Defaults to unset and kernel's default is used.
</para>
3564 <term><varname>QuantumBytes=
</varname></term>
3566 <para>Specifies the number of bytes used as the
"deficit" in the fair queuing algorithm timespan.
3567 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3568 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
3573 <term><varname>ECN=
</varname></term>
3575 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3576 unset and kernel's default is used.
</para>
3581 <term><varname>CEThresholdSec=
</varname></term>
3583 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3584 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3591 <title>[FairQueueing] Section Options
</title>
3592 <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
3595 <variablelist class='network-directives'
>
3596 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3597 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3600 <term><varname>PacketLimit=
</varname></term>
3602 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3603 dropped. Defaults to unset and kernel's default is used.
</para>
3608 <term><varname>FlowLimit=
</varname></term>
3610 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
3611 unset and kernel's default is used.
</para>
3616 <term><varname>QuantumBytes=
</varname></term>
3618 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
3619 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3620 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
3621 default is used.
</para>
3626 <term><varname>InitialQuantumBytes=
</varname></term>
3628 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
3629 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
3630 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
3631 kernel's default is used.
</para>
3636 <term><varname>MaximumRate=
</varname></term>
3638 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
3639 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
3640 1000. Defaults to unset and kernel's default is used.
</para>
3645 <term><varname>Buckets=
</varname></term>
3647 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
3648 kernel's default is used.
</para>
3653 <term><varname>OrphanMask=
</varname></term>
3655 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
3656 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
3657 kernel's default is used.
</para>
3662 <term><varname>Pacing=
</varname></term>
3664 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
3665 default is used.
</para>
3670 <term><varname>CEThresholdSec=
</varname></term>
3672 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3673 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3680 <title>[TrivialLinkEqualizer] Section Options
</title>
3681 <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
3682 equalizer (teql).
</para>
3684 <variablelist class='network-directives'
>
3685 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3686 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3689 <term><varname>Id=
</varname></term>
3691 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
3692 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
3693 <constant>max_equalizers=N+
1</constant> option must be loaded before
3694 <command>systemd-networkd
</command> is started.
</para>
3701 <title>[HierarchyTokenBucket] Section Options
</title>
3702 <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
3703 bucket (htb).
</para>
3705 <variablelist class='network-directives'
>
3706 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3707 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3710 <term><varname>DefaultClass=
</varname></term>
3712 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
3713 to the class. Defaults to unset.
</para>
3718 <term><varname>RateToQuantum=
</varname></term>
3720 <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
3721 configured in
<varname>Rate=
</varname> by
<varname>RateToQuantum=
</varname>.
</para>
3728 <title>[HierarchyTokenBucketClass] Section Options
</title>
3729 <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
3732 <variablelist class='network-directives'
>
3733 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3734 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3737 <term><varname>Priority=
</varname></term>
3739 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
3740 priority field are tried for packets first.
</para>
3745 <term><varname>QuantumBytes=
</varname></term>
3747 <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
3748 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
3754 <term><varname>MTUBytes=
</varname></term>
3756 <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
3757 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
3762 <term><varname>OverheadBytes=
</varname></term>
3764 <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
3765 computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3766 Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
3771 <term><varname>Rate=
</varname></term>
3773 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
3774 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
3775 to the base of
1000. This setting is mandatory.
</para>
3780 <term><varname>CeilRate=
</varname></term>
3782 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
3783 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
3784 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
3790 <term><varname>BufferBytes=
</varname></term>
3792 <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
3793 with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
3794 to the base of
1024.
</para>
3799 <term><varname>CeilBufferBytes=
</varname></term>
3801 <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
3802 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3803 respectively, to the base of
1024.
</para>
3810 <title>[HeavyHitterFilter] Section Options
</title>
3811 <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
3814 <variablelist class='network-directives'
>
3815 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3816 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3819 <term><varname>PacketLimit=
</varname></term>
3821 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3822 incoming packets are dropped. An unsigned integer in the range
0–
4294967294. Defaults to unset and
3823 kernel's default is used.
</para>
3830 <title>[QuickFairQueueing] Section Options
</title>
3831 <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
3834 <variablelist class='network-directives'
>
3835 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3836 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3841 <title>[QuickFairQueueingClass] Section Options
</title>
3842 <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
3845 <variablelist class='network-directives'
>
3846 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3847 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3850 <term><varname>Weight=
</varname></term>
3852 <para>Specifies the weight of the class. Takes an integer in the range
1…
1023. Defaults to
3853 unset in which case the kernel default is used.
</para>
3858 <term><varname>MaxPacketBytes=
</varname></term>
3860 <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the
3861 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
3862 1024. When unset, the kernel default is used.
</para>
3869 <title>[BridgeVLAN] Section Options
</title>
3870 <para>The [BridgeVLAN] section manages the VLAN ID configuration of a bridge port and accepts the
3871 following keys. Specify several [BridgeVLAN] sections to configure several VLAN entries. The
3872 <varname>VLANFiltering=
</varname> option has to be enabled, see the [Bridge] section in
3873 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3875 <variablelist class='network-directives'
>
3877 <term><varname>VLAN=
</varname></term>
3879 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
3880 from
1 to
4094.
</para>
3884 <term><varname>EgressUntagged=
</varname></term>
3886 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
3887 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
3888 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
3892 <term><varname>PVID=
</varname></term>
3894 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
3895 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
3896 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
3903 <title>Examples
</title>
3905 <title>Static network configuration
</title>
3907 <programlisting># /etc/systemd/network/
50-static.network
3912 Address=
192.168.0.15/
24
3913 Gateway=
192.168.0.1</programlisting>
3915 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
3916 specified gateway will be used for a default route.
</para>
3920 <title>DHCP on ethernet links
</title>
3922 <programlisting># /etc/systemd/network/
80-dhcp.network
3927 DHCP=yes
</programlisting>
3929 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
3930 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
3934 <title>IPv6 Prefix Delegation
</title>
3936 <programlisting># /etc/systemd/network/
55-ipv6-pd-upstream.network
3941 DHCP=ipv6
</programlisting>
3943 <programlisting># /etc/systemd/network/
56-ipv6-pd-downstream.network
3949 DHCPv6PrefixDelegation=yes
</programlisting>
3951 <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
3952 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
3953 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
3958 <title>A bridge with two enslaved links
</title>
3960 <programlisting># /etc/systemd/network/
25-bridge-static.network
3965 Address=
192.168.0.15/
24
3967 DNS=
192.168.0.1</programlisting>
3969 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
3974 Bridge=bridge0
</programlisting>
3976 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
3981 Bridge=bridge0
</programlisting>
3983 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
3984 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
3985 and network assigned, and a default route via the specified gateway will be
3986 added. The specified DNS server will be added to the global list of DNS resolvers.
3994 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
4010 EgressUntagged=
300-
400</programlisting>
4012 <para>This overrides the configuration specified in the previous example for the
4013 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
4014 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
4015 untagged when they leave on this interface. Untagged packets which arrive on this
4016 interface will be assigned VLAN ID
42.
</para>
4020 <title>Various tunnels
</title>
4022 <programlisting>/etc/systemd/network/
25-tunnels.network
4033 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
4039 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
4045 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
4051 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
4057 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
4058 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
4062 <title>A bond device
</title>
4064 <programlisting># /etc/systemd/network/
30-bond1.network
4072 <programlisting># /etc/systemd/network/
30-bond1.netdev
4078 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
4080 MACAddress=
52:
54:
00:e9:
64:
41
4086 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
4088 MACAddress=
52:
54:
00:e9:
64:
42
4094 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
4095 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
4096 will be used to acquire an address.
</para>
4100 <title>Virtual Routing and Forwarding (VRF)
</title>
4101 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
4102 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
4103 within the routing table defined during VRF creation. For kernels before
4.8 traffic
4104 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
4106 <programlisting># /etc/systemd/network/
25-vrf.network
4116 <title>MacVTap
</title>
4117 <para>This brings up a network interface
<literal>macvtap-test
</literal>
4118 and attaches it to
<literal>enp0s25
</literal>.
</para>
4119 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
4124 MACVTAP=macvtap-test
4129 <title>A Xfrm interface with physical underlying device.
</title>
4131 <programlisting># /etc/systemd/network/
27-xfrm.netdev
4136 InterfaceId=
7</programlisting>
4138 <programlisting># /etc/systemd/network/
27-eth0.network
4143 Xfrm=xfrm0
</programlisting>
4145 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
4146 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
4147 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
4153 <title>See Also
</title>
4155 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
4156 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
4157 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
4158 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
4159 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
projects / thirdparty / systemd.git / blob