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 parsed after the file itself is
55 parsed. This is useful to alter or add configuration settings, without having to modify the main
56 configuration file. Each drop-in file must have appropriate section headers.
</para>
58 <para>In addition to
<filename>/etc/systemd/network
</filename>, drop-in
<literal>.d
</literal>
59 directories can be placed in
<filename>/usr/lib/systemd/network
</filename> or
60 <filename>/run/systemd/network
</filename> directories. Drop-in files in
61 <filename>/etc/
</filename> take precedence over those in
<filename>/run/
</filename> which in turn
62 take precedence over those in
<filename>/usr/lib/
</filename>. Drop-in files under any of these
63 directories take precedence over the main network file wherever located.
</para>
65 <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6
66 nor IPv6LL enabled, shall be considered to have no IPv6 support. IPv6 will be automatically
67 disabled for that interface by writing
"1" to
68 <filename>/proc/sys/net/ipv6/conf/
<replaceable>ifname
</replaceable>/disable_ipv6
</filename>.
73 <title>[Match] Section Options
</title>
75 <para>The network file contains a [Match] section, which determines if a given network file may be
76 applied to a given device; and a [Network] section specifying how the device should be configured. The
77 first (in lexical order) of the network files that matches a given device is applied, all later files
78 are ignored, even if they match as well.
</para>
80 <para>A network file is said to match a network interface if all matches specified by the [Match]
81 section are satisfied. When a network file does not contain valid settings in [Match] section, then the
82 file will match all interfaces and
<command>systemd-networkd
</command> warns about that. Hint: to avoid
83 the warning and to make it clear that all interfaces shall be matched, add the following:
84 <programlisting>Name=*
</programlisting> The following keys are accepted:
</para>
86 <variablelist class='network-directives'
>
87 <xi:include href=
"systemd.link.xml" xpointer=
"mac-address" />
88 <xi:include href=
"systemd.link.xml" xpointer=
"permanent-mac-address" />
89 <xi:include href=
"systemd.link.xml" xpointer=
"path" />
90 <xi:include href=
"systemd.link.xml" xpointer=
"driver" />
91 <xi:include href=
"systemd.link.xml" xpointer=
"type" />
92 <xi:include href=
"systemd.link.xml" xpointer=
"property" />
95 <term><varname>Name=
</varname></term>
97 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
98 by the udev property
<literal>INTERFACE
</literal>, or device's alternative names. If the
99 list is prefixed with a
"!", the test is inverted.
</para>
104 <term><varname>WLANInterfaceType=
</varname></term>
106 <para>A whitespace-separated list of wireless network type. Supported values are
107 <literal>ad-hoc
</literal>,
<literal>station
</literal>,
<literal>ap
</literal>,
108 <literal>ap-vlan
</literal>,
<literal>wds
</literal>,
<literal>monitor
</literal>,
109 <literal>mesh-point
</literal>,
<literal>p2p-client
</literal>,
<literal>p2p-go
</literal>,
110 <literal>p2p-device
</literal>,
<literal>ocb
</literal>, and
<literal>nan
</literal>. If the
111 list is prefixed with a
"!", the test is inverted.
117 <term><varname>SSID=
</varname></term>
119 <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
120 connected wireless LAN. If the list is prefixed with a
"!", the test is inverted.
126 <term><varname>BSSID=
</varname></term>
128 <para>A whitespace-separated list of hardware address of the currently connected wireless
129 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
130 <varname>MACAddress=
</varname>. This option may appear more than once, in which case the
131 lists are merged. If the empty string is assigned to this option, the list is reset.
</para>
135 <xi:include href=
"systemd.link.xml" xpointer=
"host" />
136 <xi:include href=
"systemd.link.xml" xpointer=
"virtualization" />
137 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-command-line" />
138 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-version" />
139 <xi:include href=
"systemd.link.xml" xpointer=
"architecture" />
145 <title>[Link] Section Options
</title>
147 <para> The [Link] section accepts the following keys:
</para>
149 <variablelist class='network-directives'
>
151 <term><varname>MACAddress=
</varname></term>
153 <para>The hardware address to set for the device.
</para>
157 <term><varname>MTUBytes=
</varname></term>
159 <para>The maximum transmission unit in bytes to set for the
160 device. The usual suffixes K, M, G, are supported and are
161 understood to the base of
1024.
</para>
162 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
163 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
167 <term><varname>ARP=
</varname></term>
169 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
170 for this interface is enabled. When unset, the kernel's default will be used.
</para>
171 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
172 interfaces atop a single lower-level physical interface, which will then only serve as a
173 link/
"bridge" device aggregating traffic to the same physical link and not participate in
174 the network otherwise. Defaults to unset.
</para>
178 <term><varname>Multicast=
</varname></term>
180 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults to unset.
</para>
184 <term><varname>AllMulticast=
</varname></term>
186 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the network.
187 This happens when multicast routing is enabled. Defaults to unset.
</para>
191 <term><varname>Promiscuous=
</varname></term>
193 <para>Takes a boolean. If set to true, promiscuous mode of the interface is enabled.
194 Defaults to unset.
</para>
198 <term><varname>Unmanaged=
</varname></term>
200 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are
201 made to bring up or configure matching links, equivalent to
202 when there are no matching network files. Defaults to
203 <literal>no
</literal>.
</para>
204 <para>This is useful for preventing later matching network
205 files from interfering with certain interfaces that are fully
206 controlled by other applications.
</para>
210 <term><varname>Group=
</varname></term>
212 <para>Link groups are similar to port ranges found in managed switches.
213 When network interfaces are added to a numbered group, operations on
214 all the interfaces from that group can be performed at once. An unsigned
215 integer in the range
0—
4294967294. Defaults to unset.
</para>
219 <term><varname>TransmitQueues=
</varname></term>
221 <para>Specifies the devices's number of transmit queues. An integer in the range
1..
.4096.
222 When unset, the kernel's default will be used.
</para>
226 <term><varname>ReceiveQueues=
</varname></term>
228 <para>Specifies the devices's number of receive queues. An integer in the range
1..
.4096.
229 When unset, the kernel's default will be used.
</para>
233 <term><varname>RequiredForOnline=
</varname></term>
235 <para>Takes a boolean or a minimum operational state and an optional maximum operational state.
236 Please see
<citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
237 for possible operational states. When
<literal>yes
</literal>, the network is deemed required when
238 determining whether the system is online when running
239 <command>systemd-networkd-wait-online
</command>. When
<literal>no
</literal>, the network is ignored
240 when checking for online state. When a minimum operational state and an optional maximum operational
241 state are set,
<literal>yes
</literal> is implied, and this controls the minimum and maximum
242 operational state required for the network interface to be considered online.
243 Defaults to
<literal>yes
</literal>.
</para>
245 <para>The network will be brought up normally in all cases, but in
246 the event that there is no address being assigned by DHCP or the
247 cable is not plugged in, the link will simply remain offline and be
248 skipped automatically by
<command>systemd-networkd-wait-online
</command>
249 if
<literal>RequiredForOnline=no
</literal>.
</para>
256 <title>[SR-IOV] Section Options
</title>
257 <para>The [SR-IOV] section accepts the following keys. Specify several [SR-IOV] sections to configure
258 several SR-IOVs. SR-IOV provides the ability to partition a single physical PCI resource into virtual
259 PCI functions which can then be injected into a VM. In the case of network VFs, SR-IOV improves
260 north-south network performance (that is, traffic with endpoints outside the host machine) by allowing
261 traffic to bypass the host machine’s network stack.
</para>
263 <variablelist class='network-directives'
>
265 <term><varname>VirtualFunction=
</varname></term>
267 <para>Specifies a Virtual Function (VF), lightweight PCIe function designed solely to move data
268 in and out. Takes an unsigned integer in the range
0.
.2147483646. This option is compulsory.
</para>
273 <term><varname>VLANId=
</varname></term>
275 <para>Specifies VLAN ID of the virtual function. Takes an unsigned integer in the range
1.
.4095.
</para>
280 <term><varname>QualityOfService=
</varname></term>
282 <para>Specifies quality of service of the virtual function. Takes an unsigned integer in the range
1.
.4294967294.
</para>
287 <term><varname>VLANProtocol=
</varname></term>
289 <para>Specifies VLAN protocol of the virtual function. Takes
<literal>802.1Q
</literal> or
290 <literal>802.1ad
</literal>.
</para>
295 <term><varname>MACSpoofCheck=
</varname></term>
297 <para>Takes a boolean. Controls the MAC spoof checking. When unset, the kernel's default will be used.
</para>
302 <term><varname>QueryReceiveSideScaling=
</varname></term>
304 <para>Takes a boolean. Toggle the ability of querying the receive side scaling (RSS)
305 configuration of the virtual function (VF). The VF RSS information like RSS hash key may be
306 considered sensitive on some devices where this information is shared between VF and the
307 physical function (PF). When unset, the kernel's default will be used.
</para>
312 <term><varname>Trust=
</varname></term>
314 <para>Takes a boolean. Allows to set trust mode of the virtual function (VF). When set, VF
315 users can set a specific feature which may impact security and/or performance. When unset,
316 the kernel's default will be used.
</para>
321 <term><varname>LinkState=
</varname></term>
323 <para>Allows to set the link state of the virtual function (VF). Takes a boolean or a
324 special value
<literal>auto
</literal>. Setting to
<literal>auto
</literal> means a
325 reflection of the physical function (PF) link state,
<literal>yes
</literal> lets the VF to
326 communicate with other VFs on this host even if the PF link state is down,
327 <literal>no
</literal> causes the hardware to drop any packets sent by the VF. When unset,
328 the kernel's default will be used.
</para>
333 <term><varname>MACAddress=
</varname></term>
335 <para>Specifies the MAC address for the virtual function.
</para>
342 <title>[Network] Section Options
</title>
344 <para>The [Network] section accepts the following keys:
</para>
346 <variablelist class='network-directives'
>
348 <term><varname>Description=
</varname></term>
350 <para>A description of the device. This is only used for
351 presentation purposes.
</para>
355 <term><varname>DHCP=
</varname></term>
357 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
358 <literal>yes
</literal>,
<literal>no
</literal>,
359 <literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults
360 to
<literal>no
</literal>.
</para>
362 <para>Note that DHCPv6 will by default be triggered by Router
363 Advertisement, if that is enabled, regardless of this parameter.
364 By enabling DHCPv6 support explicitly, the DHCPv6 client will
365 be started regardless of the presence of routers on the link,
366 or what flags the routers pass. See
367 <literal>IPv6AcceptRA=
</literal>.
</para>
369 <para>Furthermore, note that by default the domain name
370 specified through DHCP is not used for name resolution.
371 See option
<option>UseDomains=
</option> below.
</para>
373 <para>See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the DHCP
374 client support.
</para>
378 <term><varname>DHCPServer=
</varname></term>
380 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started. Defaults
381 to
<literal>no
</literal>. Further settings for the DHCP server may be set in the [DHCPServer]
382 section described below.
</para>
386 <term><varname>LinkLocalAddressing=
</varname></term>
388 <para>Enables link-local address autoconfiguration. Accepts
<option>yes
</option>,
389 <option>no
</option>,
<option>ipv4
</option>, and
<option>ipv6
</option>. An IPv6 link-local address
390 is configured when
<option>yes
</option> or
<option>ipv6
</option>. An IPv4 link-local address is
391 configured when
<option>yes
</option> or
<option>ipv4
</option> and when DHCPv4 autoconfiguration
392 has been unsuccessful for some time. (IPv4 link-local address autoconfiguration will usually
393 happen in parallel with repeated attempts to acquire a DHCPv4 lease).
</para>
395 <para>Defaults to
<option>no
</option> when
<varname>Bridge=yes
</varname> is set, and
396 <option>ipv6
</option> otherwise.
</para>
400 <term><varname>IPv6LinkLocalAddressGenerationMode=
</varname></term>
402 <para>Specifies how IPv6 link local address is generated. Takes one of
<literal>eui64
</literal>,
403 <literal>none
</literal>,
<literal>stable-privacy
</literal> and
<literal>random
</literal>.
404 When unset, the kernel's default will be used. Note that if
<varname>LinkLocalAdressing=
</varname>
405 not configured as
<literal>ipv6
</literal> then
<varname>IPv6LinkLocalAddressGenerationMode=
</varname>
410 <term><varname>IPv4LLRoute=
</varname></term>
412 <para>Takes a boolean. If set to true, sets up the route needed for
413 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
419 <term><varname>DefaultRouteOnDevice=
</varname></term>
421 <para>Takes a boolean. If set to true, sets up the default route bound to the interface.
422 Defaults to false. This is useful when creating routes on point-to-point interfaces.
423 This is equivalent to e.g. the following.
424 <programlisting>ip route add default dev veth99
</programlisting></para>
428 <term><varname>IPv6Token=
</varname></term>
430 <para>Specifies an optional address generation mode for the Stateless Address
431 Autoconfiguration (SLAAC). Supported modes are
<literal>prefixstable
</literal> and
432 <literal>static
</literal>.
</para>
434 <para>When the mode is set to
<literal>static
</literal>, an IPv6 address must be
435 specified after a colon (
<literal>:
</literal>), and the lower bits of the supplied
436 address are combined with the upper bits of a prefix received in a Router Advertisement
437 (RA) message to form a complete address. Note that if multiple prefixes are received in an
438 RA message, or in multiple RA messages, addresses will be formed from each of them using
439 the supplied address. This mode implements SLAAC but uses a static interface identifier
440 instead of an identifier generated by using the EUI-
64 algorithm. Because the interface
441 identifier is static, if Duplicate Address Detection detects that the computed address is a
442 duplicate (in use by another node on the link), then this mode will fail to provide an
443 address for that prefix. If an IPv6 address without mode is specified, then
444 <literal>static
</literal> mode is assumed.
</para>
446 <para>When the mode is set to
<literal>prefixstable
</literal> the
447 <ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink> algorithm for generating
448 interface identifiers will be used. This mode can optionally take an IPv6 address separated
449 with a colon (
<literal>:
</literal>). If an IPv6 address is specified, then an interface
450 identifier is generated only when a prefix received in an RA message matches the supplied
453 <para>If no address generation mode is specified (which is the default), or a received
454 prefix does not match any of the addresses provided in
<literal>prefixstable
</literal>
455 mode, then the EUI-
64 algorithm will be used to form an interface identifier for that
456 prefix. This mode is also SLAAC, but with a potentially stable interface identifier which
457 does not directly map to the interface's hardware address.
</para>
459 <para>Note that the
<literal>prefixstable
</literal> algorithm uses both the interface
460 name and MAC address as input to the hash to compute the interface identifier, so if either
461 of those are changed the resulting interface identifier (and address) will change, even if
462 the prefix received in the RA message has not changed.
</para>
464 <para>This setting can be specified multiple times. If an empty string is assigned, then
465 the all previous assignments are cleared.
</para>
468 <programlisting>IPv6Token=::
1a:
2b:
3c:
4d
469 IPv6Token=static:::
1a:
2b:
3c:
4d
470 IPv6Token=prefixstable
471 IPv6Token=prefixstable:
2002:da8:
1::
</programlisting></para>
475 <term><varname>LLMNR=
</varname></term>
477 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
479 url=
"https://tools.ietf.org/html/rfc4795">Link-Local
480 Multicast Name Resolution
</ulink> on the link. When set to
481 <literal>resolve
</literal>, only resolution is enabled,
482 but not host registration and announcement. Defaults to
483 true. This setting is read by
484 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
488 <term><varname>MulticastDNS=
</varname></term>
490 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
492 url=
"https://tools.ietf.org/html/rfc6762">Multicast
493 DNS
</ulink> support on the link. When set to
494 <literal>resolve
</literal>, only resolution is enabled,
495 but not host or service registration and
496 announcement. Defaults to false. This setting is read by
497 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
501 <term><varname>DNSOverTLS=
</varname></term>
503 <para>Takes a boolean or
<literal>opportunistic
</literal>.
506 url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink>
508 When set to
<literal>opportunistic
</literal>, compatibility with
509 non-DNS-over-TLS servers is increased, by automatically
510 turning off DNS-over-TLS servers in this case.
511 This option defines a per-interface setting for
512 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
513 global
<varname>DNSOverTLS=
</varname> option. Defaults to
514 false. This setting is read by
515 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
519 <term><varname>DNSSEC=
</varname></term>
521 <para>Takes a boolean or
<literal>allow-downgrade
</literal>. When true, enables
522 <ulink url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink>
523 DNS validation support on the link. When set to
524 <literal>allow-downgrade
</literal>, compatibility with
525 non-DNSSEC capable networks is increased, by automatically
526 turning off DNSSEC in this case. This option defines a
527 per-interface setting for
528 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
529 global
<varname>DNSSEC=
</varname> option. Defaults to
530 false. This setting is read by
531 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
535 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
536 <listitem><para>A space-separated list of DNSSEC negative
537 trust anchor domains. If specified and DNSSEC is enabled,
538 look-ups done via the interface's DNS server will be subject
539 to the list of negative trust anchors, and not require
540 authentication for the specified domains, or anything below
541 it. Use this to disable DNSSEC authentication for specific
542 private domains, that cannot be proven valid using the
543 Internet DNS hierarchy. Defaults to the empty list. This
545 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
549 <term><varname>LLDP=
</varname></term>
551 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
552 implemented on professional routers and bridges which announces which physical port a system is connected
553 to, as well as other related data. Accepts a boolean or the special value
554 <literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
555 neighbors maintained. If
<literal>routers-only
</literal> is set only LLDP data of various types of routers
556 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
557 others). If false, LLDP reception is disabled. Defaults to
<literal>routers-only
</literal>. Use
558 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
559 collected neighbor data. LLDP is only available on Ethernet links. See
<varname>EmitLLDP=
</varname> below
560 for enabling LLDP packet emission from the local system.
565 <term><varname>EmitLLDP=
</varname></term>
567 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
568 <literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
569 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
570 a short LLDP packet with information about the local system is sent out in regular intervals on the
571 link. The LLDP packet will contain information about the local hostname, the local machine ID (as stored
572 in
<citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
573 local interface name, as well as the pretty hostname of the system (as set in
574 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
575 emission is only available on Ethernet links. Note that this setting passes data suitable for
576 identification of host to the network and should thus not be enabled on untrusted networks, where such
577 identification data should not be made available. Use this option to permit other systems to identify on
578 which interfaces they are connected to this system. The three special values control propagation of the
579 LLDP packets. The
<literal>nearest-bridge
</literal> setting permits propagation only to the nearest
580 connected bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays, but
581 not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until a customer bridge
582 is reached. For details about these concepts, see
<ulink
583 url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>. Note that
584 configuring this setting to true is equivalent to
<literal>nearest-bridge
</literal>, the recommended and
585 most restricted level of propagation. See
<varname>LLDP=
</varname> above for an option to enable LLDP
591 <term><varname>BindCarrier=
</varname></term>
593 <para>A link name or a list of link names. When set, controls the behavior of the current
594 link. When all links in the list are in an operational down state, the current link is brought
595 down. When at least one link has carrier, the current interface is brought up.
600 <term><varname>Address=
</varname></term>
602 <para>A static IPv4 or IPv6 address and its prefix length,
603 separated by a
<literal>/
</literal> character. Specify
604 this key more than once to configure several addresses.
605 The format of the address must be as described in
606 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
607 This is a short-hand for an [Address] section only
608 containing an Address key (see below). This option may be
609 specified more than once.
612 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
613 (for IPv6), a new address range of the requested size is automatically allocated from a
614 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
615 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
616 all known network configuration files to avoid address range conflicts. The default system-wide
617 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.
618 This functionality is useful to manage a large number of dynamically created network interfaces
619 with the same network configuration and automatic address range assignment.
</para>
624 <term><varname>Gateway=
</varname></term>
626 <para>The gateway address, which must be in the format
628 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
629 This is a short-hand for a [Route] section only containing
630 a Gateway key. This option may be specified more than
635 <term><varname>DNS=
</varname></term>
637 <para>A DNS server address, which must be in the format
639 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
640 This option may be specified more than once. Each address can optionally take a port number
641 separated with
<literal>:
</literal>, a network interface name or index separated with
642 <literal>%
</literal>, and a Server Name Indication (SNI) separated with
<literal>#
</literal>.
643 When IPv6 address is specified with a port number, then the address must be in the square
644 brackets. That is, the acceptable full formats are
645 <literal>111.222.333.444:
9953%ifname#example.com
</literal> for IPv4 and
646 <literal>[
1111:
2222::
3333]:
9953%ifname#example.com
</literal> for IPv6. This setting can be
647 specified multiple times. If an empty string is assigned, then the all previous assignments
648 are cleared. This setting is read by
649 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
653 <term><varname>Domains=
</varname></term>
655 <para>A whitespace-separated list of domains which should be resolved using the DNS servers on
656 this link. Each item in the list should be a domain name, optionally prefixed with a tilde
657 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
658 domains without the prefix are called
"search domains" and are first used as search suffixes for
659 extending single-label hostnames (hostnames containing no dots) to become fully qualified
660 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
661 specified search domains are appended to it in turn, converting it into a fully qualified domain
662 name, until one of them may be successfully resolved.
</para>
664 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for hostnames
665 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
666 the DNS servers configured for this interface. The domain routing logic is particularly useful on
667 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
669 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
670 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
671 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
672 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
673 if a link on which they are connected is available.
</para>
675 <para>This setting is read by
676 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
677 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
678 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
679 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
680 name servers limited to a specific link.
</para>
684 <term><varname>DNSDefaultRoute=
</varname></term>
686 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
687 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
688 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
689 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
690 queries not matching any link's configured domains will be routed to this link if it has no routing-only
691 domains configured.
</para>
695 <term><varname>NTP=
</varname></term>
697 <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
698 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
702 <term><varname>IPForward=
</varname></term>
703 <listitem><para>Configures IP packet forwarding for the
704 system. If enabled, incoming packets on any network
705 interface will be forwarded to any other interfaces
706 according to the routing table. Takes a boolean,
707 or the values
<literal>ipv4
</literal> or
708 <literal>ipv6
</literal>, which only enable IP packet
709 forwarding for the specified address family. This controls
710 the
<filename>net.ipv4.ip_forward
</filename> and
711 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
712 options of the network interface (see
<ulink
713 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
714 for details about sysctl options). Defaults to
715 <literal>no
</literal>.
</para>
717 <para>Note: this setting controls a global kernel option,
718 and does so one way only: if a network that has this setting
719 enabled is set up the global setting is turned on. However,
720 it is never turned off again, even after all networks with
721 this setting enabled are shut down again.
</para>
723 <para>To allow IP packet forwarding only between specific
724 network interfaces use a firewall.
</para>
728 <term><varname>IPMasquerade=
</varname></term>
729 <listitem><para>Configures IP masquerading for the network
730 interface. If enabled, packets forwarded from the network
731 interface will be appear as coming from the local host.
732 Takes a boolean argument. Implies
733 <varname>IPForward=ipv4
</varname>. Defaults to
734 <literal>no
</literal>.
</para></listitem>
737 <term><varname>IPv6PrivacyExtensions=
</varname></term>
738 <listitem><para>Configures use of stateless temporary
739 addresses that change over time (see
<ulink
740 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
741 Privacy Extensions for Stateless Address Autoconfiguration
742 in IPv6). Takes a boolean or the special values
743 <literal>prefer-public
</literal> and
744 <literal>kernel
</literal>. When true, enables the privacy
745 extensions and prefers temporary addresses over public
746 addresses. When
<literal>prefer-public
</literal>, enables the
747 privacy extensions, but prefers public addresses over
748 temporary addresses. When false, the privacy extensions
749 remain disabled. When
<literal>kernel
</literal>, the kernel's
750 default setting will be left in place. Defaults to
751 <literal>no
</literal>.
</para></listitem>
754 <term><varname>IPv6AcceptRA=
</varname></term>
755 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
756 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they may
757 trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or if no
758 routers are found on the link. The default is to disable RA reception for bridge devices or when IP
759 forwarding is enabled, and to enable it otherwise. Cannot be enabled on bond devices and when link
760 local addressing is disabled.
</para>
762 <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA] section, see
765 <para>Also see
<ulink
766 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink> in the kernel
767 documentation regarding
<literal>accept_ra
</literal>, but note that systemd's setting of
768 <constant>1</constant> (i.e. true) corresponds to kernel's setting of
<constant>2</constant>.
</para>
770 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
771 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
772 RA protocol is used, and the kernel's own implementation remains disabled, since
773 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
774 and these are not available from the kernel if the kernel's own implementation is used.
</para>
778 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
779 <listitem><para>Configures the amount of IPv6 Duplicate
780 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
784 <term><varname>IPv6HopLimit=
</varname></term>
785 <listitem><para>Configures IPv6 Hop Limit. For each router that
786 forwards the packet, the hop limit is decremented by
1. When the
787 hop limit field reaches zero, the packet is discarded.
788 When unset, the kernel's default will be used.
792 <term><varname>IPv4AcceptLocal=
</varname></term>
793 <listitem><para>Takes a boolean. Accept packets with local source addresses. In combination
794 with suitable routing, this can be used to direct packets between two local interfaces over
795 the wire and have them accepted properly. When unset, the kernel's default will be used.
799 <term><varname>IPv4ProxyARP=
</varname></term>
800 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
801 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
802 the router accepts responsibility for routing packets to the
"real" destination. See
<ulink
803 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
804 When unset, the kernel's default will be used.
808 <term><varname>IPv6ProxyNDP=
</varname></term>
809 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
810 Protocol) is a technique for IPv6 to allow routing of addresses to a different
811 destination when peers expect them to be present on a certain physical link.
812 In this case a router answers Neighbour Advertisement messages intended for
813 another machine by offering its own MAC address as destination.
814 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
815 Advertisement messages for addresses in the IPv6 neighbor proxy table,
816 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
817 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
818 interface depending on this option.
819 When unset, the kernel's default will be used.
823 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
824 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
825 proxied. This option may be specified more than once. systemd-networkd will add the
826 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
827 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
828 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
832 <term><varname>IPv6SendRA=
</varname></term>
833 <listitem><para>Whether to enable or disable Router Advertisement sending on a link. Takes a
834 boolean value. When enabled, prefixes configured in [IPv6Prefix] sections and routes
835 configured in [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA]
836 section. If
<varname>DHCPv6PrefixDelegation=
</varname> is enabled, then the delegated
837 prefixes are also distributed. See
<varname>DHCPv6PrefixDelegation=
</varname> setting and the
838 [IPv6SendRA], [IPv6Prefix], [IPv6RoutePrefix], and [DHCPv6PrefixDelegation] sections for more
839 configuration options.
</para></listitem>
842 <term><varname>DHCPv6PrefixDelegation=
</varname></term>
843 <listitem><para>Takes a boolean value. When enabled, requests prefixes using a DHCPv6 client
844 configured on another link. By default, an address within each delegated prefix will be
845 assigned, and the prefixes will be announced through IPv6 Router Advertisement when
846 <varname>IPv6SendRA=
</varname> is enabled. Such default settings can be configured in
847 [DHCPv6PrefixDelegation] section. Defaults to disabled.
</para></listitem>
850 <term><varname>IPv6MTUBytes=
</varname></term>
851 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
852 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
856 <term><varname>Bridge=
</varname></term>
858 <para>The name of the bridge to add the link to. See
859 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
864 <term><varname>Bond=
</varname></term>
866 <para>The name of the bond to add the link to. See
867 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
872 <term><varname>VRF=
</varname></term>
874 <para>The name of the VRF to add the link to. See
875 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
880 <term><varname>VLAN=
</varname></term>
882 <para>The name of a VLAN to create on the link. See
883 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
884 This option may be specified more than once.
</para>
888 <term><varname>IPVLAN=
</varname></term>
890 <para>The name of a IPVLAN to create on the link. See
891 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
892 This option may be specified more than once.
</para>
896 <term><varname>MACVLAN=
</varname></term>
898 <para>The name of a MACVLAN to create on the link. See
899 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
900 This option may be specified more than once.
</para>
904 <term><varname>VXLAN=
</varname></term>
906 <para>The name of a VXLAN to create on the link. See
907 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
908 This option may be specified more than once.
</para>
912 <term><varname>Tunnel=
</varname></term>
914 <para>The name of a Tunnel to create on the link. See
915 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
916 This option may be specified more than once.
</para>
920 <term><varname>MACsec=
</varname></term>
922 <para>The name of a MACsec device to create on the link. See
923 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
924 This option may be specified more than once.
</para>
928 <term><varname>ActiveSlave=
</varname></term>
930 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
931 option is only valid for following modes:
932 <literal>active-backup
</literal>,
933 <literal>balance-alb
</literal> and
934 <literal>balance-tlb
</literal>. Defaults to false.
939 <term><varname>PrimarySlave=
</varname></term>
941 <para>Takes a boolean. Specifies which slave is the primary device. The specified
942 device will always be the active slave while it is available. Only when the
943 primary is off-line will alternate devices be used. This is useful when
944 one slave is preferred over another, e.g. when one slave has higher throughput
945 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
947 <literal>active-backup
</literal>,
948 <literal>balance-alb
</literal> and
949 <literal>balance-tlb
</literal>. Defaults to false.
954 <term><varname>ConfigureWithoutCarrier=
</varname></term>
956 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
957 Defaults to false. If
<option>IgnoreCarrierLoss=
</option> is not explicitly set, it will
958 default to this value.
963 <term><varname>IgnoreCarrierLoss=
</varname></term>
965 <para>Takes a boolean. Allows networkd to retain both the static and dynamic configuration
966 of the interface even if its carrier is lost. When unset, the value specified with
967 <option>ConfigureWithoutCarrier=
</option> is used.
972 <term><varname>Xfrm=
</varname></term>
974 <para>The name of the xfrm to create on the link. See
975 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
976 This option may be specified more than once.
</para>
980 <term><varname>KeepConfiguration=
</varname></term>
982 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
983 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
984 will not drop static addresses and routes on starting up process. When set to
985 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
986 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
987 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
988 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
989 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
990 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
991 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
<literal>no
</literal>.
1001 <title>[Address] Section Options
</title>
1003 <para>An [Address] section accepts the following keys. Specify several [Address]
1004 sections to configure several addresses.
</para>
1006 <variablelist class='network-directives'
>
1008 <term><varname>Address=
</varname></term>
1010 <para>As in the [Network] section. This key is mandatory. Each [Address] section can contain one
1011 <varname>Address=
</varname> setting.
</para>
1015 <term><varname>Peer=
</varname></term>
1017 <para>The peer address in a point-to-point connection.
1018 Accepts the same format as the
<varname>Address=
</varname>
1023 <term><varname>Broadcast=
</varname></term>
1025 <para>The broadcast address, which must be in the format
1027 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1028 This key only applies to IPv4 addresses. If it is not
1029 given, it is derived from the
<varname>Address=
</varname>
1034 <term><varname>Label=
</varname></term>
1036 <para>An address label.
</para>
1040 <term><varname>PreferredLifetime=
</varname></term>
1042 <para>Allows the default
"preferred lifetime" of the address to be overridden.
1043 Only three settings are accepted:
<literal>forever
</literal> or
<literal>infinity
</literal>
1044 which is the default and means that the address never expires, and
<literal>0</literal> which means
1045 that the address is considered immediately
"expired" and will not be used,
1046 unless explicitly requested. A setting of PreferredLifetime=
0 is useful for
1047 addresses which are added to be used only by a specific application,
1048 which is then configured to use them explicitly.
</para>
1052 <term><varname>Scope=
</varname></term>
1054 <para>The scope of the address, which can be
<literal>global
</literal>,
1055 <literal>link
</literal> or
<literal>host
</literal> or an unsigned integer in the range
0—
255.
1056 Defaults to
<literal>global
</literal>.
</para>
1060 <term><varname>HomeAddress=
</varname></term>
1062 <para>Takes a boolean. Designates this address the
"home address" as defined in
1063 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
1064 Supported only on IPv6. Defaults to false.
</para>
1068 <term><varname>DuplicateAddressDetection=
</varname></term>
1070 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
1071 <literal>both
</literal>,
<literal>none
</literal>. When
<literal>ipv4
</literal>,
1072 performs IPv4 Duplicate Address Detection. See
1073 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
1074 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
1075 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>.
1076 Defaults to
<literal>ipv6
</literal>.
</para>
1080 <term><varname>ManageTemporaryAddress=
</varname></term>
1082 <para>Takes a boolean. If true the kernel manage temporary addresses created
1083 from this one as template on behalf of Privacy Extensions
1084 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
1085 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
1086 The given address needs to have a prefix length of
64. This flag allows using privacy
1087 extensions in a manually configured network, just like if stateless auto-configuration
1088 was active. Defaults to false.
</para>
1092 <term><varname>AddPrefixRoute=
</varname></term>
1094 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
1095 Defaults to true.
</para>
1099 <term><varname>AutoJoin=
</varname></term>
1101 <para>Takes a boolean. Joining multicast group on ethernet level via
1102 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
1103 IGMP snooping since the switch would not replicate multicast packets on ports that did not
1104 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
1105 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
1106 that enables then to do the required join. By extending ip address command with option
1107 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
1108 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
1109 Defaults to
<literal>no
</literal>.
</para>
1116 <title>[Neighbor] Section Options
</title>
1117 <para>A [Neighbor] section accepts the following keys. The neighbor section adds a permanent, static
1118 entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the links
1119 matched for the network. Specify several [Neighbor] sections to configure several static neighbors.
1122 <variablelist class='network-directives'
>
1124 <term><varname>Address=
</varname></term>
1126 <para>The IP address of the neighbor.
</para>
1130 <term><varname>LinkLayerAddress=
</varname></term>
1132 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
1139 <title>[IPv6AddressLabel] Section Options
</title>
1141 <para>An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel]
1142 sections to configure several address labels. IPv6 address labels are used for address selection. See
1143 <ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>. Precedence is managed by userspace,
1144 and only the label itself is stored in the kernel.
</para>
1146 <variablelist class='network-directives'
>
1148 <term><varname>Label=
</varname></term>
1150 <para>The label for the prefix, an unsigned integer in the range
0–
4294967294.
1151 0xffffffff is reserved. This setting is mandatory.
</para>
1155 <term><varname>Prefix=
</varname></term>
1157 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
1158 This key is mandatory.
</para>
1165 <title>[RoutingPolicyRule] Section Options
</title>
1167 <para>An [RoutingPolicyRule] section accepts the following keys. Specify several [RoutingPolicyRule]
1168 sections to configure several rules.
</para>
1170 <variablelist class='network-directives'
>
1172 <term><varname>TypeOfService=
</varname></term>
1174 <para>Takes a number between
0 and
255 that specifies the type of service to match.
</para>
1178 <term><varname>From=
</varname></term>
1180 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1184 <term><varname>To=
</varname></term>
1186 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1190 <term><varname>FirewallMark=
</varname></term>
1192 <para>Specifies the iptables firewall mark value to match (a number between
1 and
1193 4294967295). Optionally, the firewall mask (also a number between
1 and
4294967295) can be
1194 suffixed with a slash (
<literal>/
</literal>), e.g.,
<literal>7/
255</literal>.
</para>
1198 <term><varname>Table=
</varname></term>
1200 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes
1201 one of
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
1202 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1206 <term><varname>Priority=
</varname></term>
1208 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1209 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1213 <term><varname>IncomingInterface=
</varname></term>
1215 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1219 <term><varname>OutgoingInterface=
</varname></term>
1221 <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>
1225 <term><varname>SourcePort=
</varname></term>
1227 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1228 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1232 <term><varname>DestinationPort=
</varname></term>
1234 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1235 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1239 <term><varname>IPProtocol=
</varname></term>
1241 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1242 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1243 <literal>17</literal> for
<literal>udp
</literal>.
1244 Defaults to unset.
</para>
1248 <term><varname>InvertRule=
</varname></term>
1250 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1254 <term><varname>Family=
</varname></term>
1256 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1257 <literal>both
</literal>. By default, the address family is determined by the address
1258 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1259 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1260 <literal>ipv4
</literal>.
</para>
1264 <term><varname>User=
</varname></term>
1266 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1271 <term><varname>SuppressPrefixLength=
</varname></term>
1273 <para>Takes a number
<replaceable>N
</replaceable> in the range
0-
128 and rejects routing
1274 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1279 <term><varname>Type=
</varname></term>
1281 <para>Specifies Routing Policy Database (RPDB) rule type. Takes one of
<literal>blackhole
</literal>,
1282 <literal>unreachable
</literal> or
<literal>prohibit
</literal>.
1290 <title>[NextHop] Section Options
</title>
1291 <para>The [NextHop] section is used to manipulate entries in the kernel's
"nexthop" tables. The
1292 [NextHop] section accepts the following keys. Specify several [NextHop] sections to configure several
1295 <variablelist class='network-directives'
>
1297 <term><varname>Gateway=
</varname></term>
1299 <para>As in the [Network] section. This is mandatory.
</para>
1303 <term><varname>Id=
</varname></term>
1305 <para>The id of the nexthop (an unsigned integer). If unspecified or '
0' then automatically chosen by kernel.
</para>
1312 <title>[Route] Section Options
</title>
1313 <para>The [Route] section accepts the following keys. Specify several [Route] sections to configure
1314 several routes.
</para>
1316 <variablelist class='network-directives'
>
1318 <term><varname>Gateway=
</varname></term>
1320 <para>Takes the gateway address or the special values
<literal>_dhcp4
</literal> and
1321 <literal>_ipv6ra
</literal>. If
<literal>_dhcp4
</literal> or
<literal>_ipv6ra
</literal> is
1322 set, then the gateway address provided by DHCPv4 or IPv6 RA is used.
</para>
1326 <term><varname>GatewayOnLink=
</varname></term>
1328 <para>Takes a boolean. If set to true, the kernel does not have
1329 to check if the gateway is reachable directly by the current machine (i.e., the kernel does
1330 not need to check if the gateway is attached to the local network), so that we can insert the
1331 route in the kernel table without it being complained about. Defaults to
<literal>no
</literal>.
1336 <term><varname>Destination=
</varname></term>
1338 <para>The destination prefix of the route. Possibly
1339 followed by a slash and the prefix length. If omitted, a
1340 full-length host route is assumed.
</para>
1344 <term><varname>Source=
</varname></term>
1346 <para>The source prefix of the route. Possibly followed by
1347 a slash and the prefix length. If omitted, a full-length
1348 host route is assumed.
</para>
1352 <term><varname>Metric=
</varname></term>
1354 <para>The metric of the route (an unsigned integer).
</para>
1358 <term><varname>IPv6Preference=
</varname></term>
1360 <para>Specifies the route preference as defined in
<ulink
1361 url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink> for Router Discovery messages. Which
1362 can be one of
<literal>low
</literal> the route has a lowest priority,
<literal>medium
</literal>
1363 the route has a default priority or
<literal>high
</literal> the route has a highest priority.
1368 <term><varname>Scope=
</varname></term>
1370 <para>The scope of the route, which can be
<literal>global
</literal>,
<literal>site
</literal>,
1371 <literal>link
</literal>,
<literal>host
</literal>, or
<literal>nowhere
</literal>. For IPv4 route,
1372 defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
<literal>local
</literal>
1373 or
<literal>nat
</literal>, and
<literal>link
</literal> if
<varname>Type=
</varname> is
1374 <literal>broadcast
</literal>,
<literal>multicast
</literal>, or
<literal>anycast
</literal>.
1375 In other cases, defaults to
<literal>global
</literal>.
</para>
1379 <term><varname>PreferredSource=
</varname></term>
1381 <para>The preferred source address of the route. The address
1382 must be in the format described in
1383 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1387 <term><varname>Table=
</varname></term>
1389 <para>The table identifier for the route. Takes
<literal>default
</literal>,
1390 <literal>main
</literal>,
<literal>local
</literal> or a number between
1 and
4294967295.
1391 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1392 If unset and
<varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1393 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1394 In other cases, defaults to
<literal>main
</literal>.
1399 <term><varname>Protocol=
</varname></term>
1401 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1402 <literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1403 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1408 <term><varname>Type=
</varname></term>
1410 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1411 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1412 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1413 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1414 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1415 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1416 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1417 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1418 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1419 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1420 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1425 <term><varname>InitialCongestionWindow=
</varname></term>
1427 <para>The TCP initial congestion window is used during the start of a TCP connection.
1428 During the start of a TCP session, when a client requests a resource, the server's initial
1429 congestion window determines how many packets will be sent during the initial burst of data
1430 without waiting for acknowledgement. Takes a number between
1 and
1023. Note that
100 is
1431 considered an extremely large value for this option. When unset, the kernel's default
1432 (typically
10) will be used.
</para>
1436 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1438 <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
1439 that can initially be buffered at one time on a connection. The sending host can send only
1440 that amount of data before waiting for an acknowledgment and window update from the
1441 receiving host. Takes a number between
1 and
1023. Note that
100 is considered an extremely
1442 large value for this option. When unset, the kernel's default will be used.
</para>
1446 <term><varname>QuickAck=
</varname></term>
1448 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1453 <term><varname>FastOpenNoCookie=
</varname></term>
1455 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1456 When unset, the kernel's default will be used.
1461 <term><varname>TTLPropagate=
</varname></term>
1463 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1464 When unset, the kernel's default will be used.
1469 <term><varname>MTUBytes=
</varname></term>
1471 <para>The maximum transmission unit in bytes to set for the
1472 route. The usual suffixes K, M, G, are supported and are
1473 understood to the base of
1024.
</para>
1474 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1475 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1479 <term><varname>IPServiceType=
</varname></term>
1481 <para>Takes string;
<literal>CS6
</literal> or
<literal>CS4
</literal>. Used to set IP
1482 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.
</para>
1486 <term><varname>TCPAdvertisedMaximumSegmentSize=
</varname></term>
1488 <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G, are
1489 supported and are understood to the base of
1024. An unsigned integer in the range
1–
4294967294.
1490 When unset, the kernel's default will be used.
</para>
1494 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1496 <para>Configures multipath route. Multipath routing is the technique of using multiple
1497 alternative paths through a network. Takes gateway address. Optionally, takes a network
1498 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for
1499 this multipath route separated with whitespace. This setting can be specified multiple
1500 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
1507 <title>[DHCPv4] Section Options
</title>
1508 <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
1509 <varname>DHCP=
</varname> setting described above:
</para>
1511 <variablelist class='network-directives'
>
1513 <term><varname>UseDNS=
</varname></term>
1515 <para>When true (the default), the DNS servers received
1516 from the DHCP server will be used and take precedence over
1517 any statically configured ones.
</para>
1519 <para>This corresponds to the
<option>nameserver
</option>
1520 option in
<citerefentry
1521 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1525 <term><varname>RoutesToDNS=
</varname></term>
1527 <para>When true, the routes to the DNS servers received from the DHCP server will be
1528 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored.
1529 Defaults to false.
</para>
1533 <term><varname>UseNTP=
</varname></term>
1535 <para>When true (the default), the NTP servers received from the DHCP server will be used by
1536 <filename>systemd-timesyncd.service
</filename> and take precedence over any statically configured
1541 <term><varname>UseSIP=
</varname></term>
1543 <para>When true (the default), the SIP servers received from the DHCP server will be collected
1544 and made available to client programs.
</para>
1549 <term><varname>UseMTU=
</varname></term>
1551 <para>When true, the interface maximum transmission unit
1552 from the DHCP server will be used on the current link.
1553 If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
1554 Defaults to false.
</para>
1558 <term><varname>Anonymize=
</varname></term>
1560 <para>Takes a boolean. When true, the options sent to the DHCP server will
1561 follow the
<ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink>
1562 (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying information.
1563 Defaults to false.
</para>
1565 <para>This option should only be set to true when
1566 <varname>MACAddressPolicy=
</varname> is set to
<literal>random
</literal>
1568 project='man-pages'
><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
1570 <para>Note that this configuration will overwrite others.
1571 In concrete, the following variables will be ignored:
1572 <varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1573 <varname>UseRoutes=
</varname>,
<varname>UseMTU=
</varname>,
1574 <varname>VendorClassIdentifier=
</varname>,
<varname>UseTimezone=
</varname>.
</para>
1576 <para>With this option enabled DHCP requests will mimic those generated by Microsoft Windows, in
1577 order to reduce the ability to fingerprint and recognize installations. This means DHCP request
1578 sizes will grow and lease data will be more comprehensive than normally, though most of the
1579 requested data is not actually used.
</para>
1583 <term><varname>SendHostname=
</varname></term>
1585 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1586 Note that the machine's hostname must consist only of
7-bit ASCII lower-case characters and
1587 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1588 sent even if this is set to true.
</para>
1593 <term><varname>MUDURL=
</varname></term>
1595 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent to the
1596 DHCPv4 server. Takes a URL of length up to
255 characters. A superficial verification that the
1597 string is a valid URL will be performed. DHCPv4 clients are intended to have at most one MUD URL
1598 associated with them. See
<ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
1601 <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers to
1602 advertise device specifications, including the intended communication patterns for their device
1603 when it connects to the network. The network can then use this to author a context-specific
1604 access policy, so the device functions only within those parameters.
</para>
1609 <term><varname>UseHostname=
</varname></term>
1611 <para>When true (the default), the hostname received from
1612 the DHCP server will be set as the transient hostname of the system.
1617 <term><varname>Hostname=
</varname></term>
1619 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1620 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1621 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1625 <term><varname>UseDomains=
</varname></term>
1627 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1628 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1629 the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name received from
1630 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1631 the
<option>Domains=
</option> setting when the argument is prefixed with
<literal>~
</literal>. Defaults to
1634 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1635 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
1636 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1637 single-label names.
</para>
1639 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1640 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1644 <term><varname>UseRoutes=
</varname></term>
1646 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1647 routing table with a metric of
1024, and a scope of
"global",
"link" or
"host", depending on the route's
1648 destination and gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the
1649 link's own address, the scope will be set to
"host". Otherwise if the gateway is null (a direct route), a
1650 "link" scope will be used. For anything else, scope defaults to
"global".
</para>
1654 <term><varname>UseGateway=
</varname></term>
1656 <para>When true, the gateway will be requested from the DHCP server and added to the routing table with a
1657 metric of
1024, and a scope of
"link". When unset, the value specified with
<option>UseRoutes=
</option>
1662 <term><varname>UseTimezone=
</varname></term>
1664 <listitem><para>When true, the timezone received from the
1665 DHCP server will be set as timezone of the local
1666 system. Defaults to
<literal>no
</literal>.
</para></listitem>
1670 <term><varname>ClientIdentifier=
</varname></term>
1672 <para>The DHCPv4 client identifier to use. Takes one of
<literal>mac
</literal>,
<literal>duid
</literal> or
<literal>duid-only
</literal>.
1673 If set to
<literal>mac
</literal>, the MAC address of the link is used.
1674 If set to
<literal>duid
</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1675 If set to
<literal>duid-only
</literal>, only DUID is used, this may not be RFC compliant, but some setups may require to use this.
1676 Defaults to
<literal>duid
</literal>.
</para>
1681 <term><varname>VendorClassIdentifier=
</varname></term>
1683 <para>The vendor class identifier used to identify vendor
1684 type and configuration.
</para>
1689 <term><varname>UserClass=
</varname></term>
1691 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1692 it represents. The information contained in this option is a string that represents the user class of which
1693 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1694 service to classify clients. Takes a whitespace-separated list of strings.
</para>
1699 <term><varname>MaxAttempts=
</varname></term>
1701 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1702 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>. Note that the
1703 time between retries is increased exponentially, up to approximately one per minute, so the
1704 network will not be overloaded even if this number is high. The default is suitable in most
1705 circumstances.
</para>
1710 <term><varname>DUIDType=
</varname></term>
1712 <para>Override the global
<varname>DUIDType
</varname> setting for this network. See
1713 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1714 for a description of possible values.
</para>
1719 <term><varname>DUIDRawData=
</varname></term>
1721 <para>Override the global
<varname>DUIDRawData
</varname> setting for this network. See
1722 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1723 for a description of possible values.
</para>
1728 <term><varname>IAID=
</varname></term>
1730 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned integer.
</para>
1735 <term><varname>RequestBroadcast=
</varname></term>
1737 <para>Request the server to use broadcast messages before
1738 the IP address has been configured. This is necessary for
1739 devices that cannot receive RAW packets, or that cannot
1740 receive packets at all before an IP address has been
1741 configured. On the other hand, this must not be enabled on
1742 networks where broadcasts are filtered out.
</para>
1747 <term><varname>RouteMetric=
</varname></term>
1749 <para>Set the routing metric for routes specified by the DHCP server. Defaults to
1024.
</para>
1754 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1756 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1757 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1759 <para>When used in combination with
<varname>VRF=
</varname>, the
1760 VRF's routing table is used when this parameter is not specified.
1766 <term><varname>RouteMTUBytes=
</varname></term>
1768 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.
</para>
1773 <term><varname>ListenPort=
</varname></term>
1775 <para>Allow setting custom port for the DHCP client to listen on.
</para>
1780 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
1782 <para>Allows to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease lifetime.
1783 Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal> means that the address
1784 never expires. Defaults to unset.
</para>
1789 <term><varname>SendRelease=
</varname></term>
1791 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops.
1792 Defaults to true.
</para>
1797 <term><varname>SendDecline=
</varname></term>
1799 <para>A boolean. When
<literal>true
</literal>, the DHCPv4 client receives the IP address from the
1800 DHCP server. After a new IP is received, the DHCPv4 client performs IPv4 Duplicate Address
1801 Detection. If duplicate use is detected, the DHCPv4 client rejects the IP by sending a
1802 DHCPDECLINE packet and tries to obtain an IP address again. See
<ulink
1803 url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>. Defaults to
1804 <literal>unset
</literal>.
</para>
1809 <term><varname>DenyList=
</varname></term>
1811 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are rejected. Note that
1812 if
<varname>AllowList=
</varname> is configured then
<varname>DenyList=
</varname> is ignored.
</para>
1817 <term><varname>AllowList=
</varname></term>
1819 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are accepted.
</para>
1824 <term><varname>RequestOptions=
</varname></term>
1826 <para>When configured, allows to set arbitrary request options in the DHCPv4 request options list and will be
1827 sent to the DHCPV4 server. A whitespace-separated list of integers in the range
1.
.254. Defaults to unset.
</para>
1832 <term><varname>SendOption=
</varname></term>
1834 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data type
1835 and data separated with a colon
1836 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1837 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1838 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1839 <literal>string
</literal>. Special characters in the data string may be escaped using
1840 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1841 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1842 then all options specified earlier are cleared. Defaults to unset.
</para>
1847 <term><varname>SendVendorOption=
</varname></term>
1849 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data type
1850 and data separated with a colon
1851 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1852 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1853 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1854 <literal>string
</literal>. Special characters in the data string may be escaped using
1855 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1856 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1857 then all options specified earlier are cleared. Defaults to unset.
</para>
1864 <title>[DHCPv6] Section Options
</title>
1865 <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
1866 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
</para>
1868 <variablelist class='network-directives'
>
1870 <term><varname>UseAddress=
</varname></term>
1872 <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
1878 <term><varname>UseDNS=
</varname></term>
1879 <term><varname>UseNTP=
</varname></term>
1881 <para>As in the [DHCPv4] section.
</para>
1886 <term><varname>RouteMetric=
</varname></term>
1888 <para>Set the routing metric for routes specified by the DHCP server. Defaults to
1024.
</para>
1893 <term><varname>RapidCommit=
</varname></term>
1895 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1896 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1897 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1898 four-message exchange (solicit, advertise, request, and reply). The two-message exchange provides
1899 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1900 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
1901 Defaults to true.
</para>
1906 <term><varname>MUDURL=
</varname></term>
1908 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent to
1909 the DHCPV6 server. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
1910 [DHCPv4] section described above.
</para>
1915 <term><varname>RequestOptions=
</varname></term>
1917 <para>When configured, allows to set arbitrary request options in the DHCPv6 request options list
1918 that will be sent to the DHCPV6 server. A whitespace-separated list of integers in the range
1919 1.
.254. Defaults to unset.
</para>
1924 <term><varname>SendVendorOption=
</varname></term>
1926 <para>Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier, DHCP
1927 option number, data type, and data separated with a colon (
<literal><replaceable>enterprise
1928 identifier
</replaceable>:
<replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
1929 <replaceable>value
</replaceable></literal>). Enterprise identifier is an unsigned integer in the
1930 range
1–
4294967294. The option number must be an integer in the range
1–
254. Data type takes one
1931 of
<literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
1932 <literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
1933 <literal>string
</literal>. Special characters in the data string may be escaped using
<ulink
1934 url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1935 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1936 then all options specified earlier are cleared. Defaults to unset.
</para>
1941 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
1943 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
1944 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
1945 makes DHCPv6 request network information in a stateless manner using a two-message Information
1946 Request and Information Reply message exchange.
1947 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
1948 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
1949 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
1950 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
1951 By default this option is set to 'false', enable it if no prefixes are delegated when the device
1952 should be acting as a CE router.
</para>
1957 <term><varname>PrefixDelegationHint=
</varname></term>
1959 <para>Takes an IPv6 address with prefix length in the same format as the
1960 <varname>Address=
</varname> in the [Network] section. The DHCPv6 client will include a prefix
1961 hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
1962 1–
128. Defaults to unset.
</para>
1967 <term><varname>WithoutRA=
</varname></term>
1969 <para>Allows DHCPv6 client to start without router advertisements's managed or other address
1970 configuration flag. Takes one of
<literal>solicit
</literal> or
1971 <literal>information-request
</literal>. Defaults to unset.
</para>
1976 <term><varname>SendOption=
</varname></term>
1978 <para>As in the [DHCPv4] section, however because DHCPv6 uses
16-bit fields to store
1979 option numbers, the option number is an integer in the range
1.
.65536.
</para>
1984 <term><varname>UserClass=
</varname></term>
1986 <para>A DHCPv6 client can use User Class option to identify the type or category of user or applications
1987 it represents. The information contained in this option is a string that represents the user class of which
1988 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1989 service to classify clients. Special characters in the data string may be escaped using
1990 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1991 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1992 then all options specified earlier are cleared. Takes a whitespace-separated list of strings. Note that
1993 currently
<constant>NUL
</constant> bytes are not allowed.
</para>
1998 <term><varname>VendorClass=
</varname></term>
2000 <para>A DHCPv6 client can use VendorClass option to identify the vendor that
2001 manufactured the hardware on which the client is running. The information
2002 contained in the data area of this option is contained in one or more opaque
2003 fields that identify details of the hardware configuration. Takes a
2004 whitespace-separated list of strings.
</para>
2011 <title>[DHCPv6PrefixDelegation] Section Options
</title>
2012 <para>The [DHCPv6PrefixDelegation] section configures delegated prefixes assigned by DHCPv6 server.
2013 The settings in this section are used only when
<varname>DHCPv6PrefixDelegation=
</varname> setting
2016 <variablelist class='network-directives'
>
2018 <term><varname>SubnetId=
</varname></term>
2020 <para>Configure a specific subnet ID on the interface from a (previously) received prefix
2021 delegation. You can either set
"auto" (the default) or a specific subnet ID (as defined in
2022 <ulink url=
"https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC
4291</ulink>, section
2023 2.5.4), in which case the allowed value is hexadecimal, from
0 to
0x7fffffffffffffff
2029 <term><varname>Announce=
</varname></term>
2031 <para>Takes a boolean. When enabled, and
<varname>IPv6SendRA=
</varname> in [Network] section
2032 is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
2033 Defaults to yes.
</para>
2038 <term><varname>Assign=
</varname></term>
2040 <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
2041 are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
2042 interfce), the EUI-
64 algorithm will be used by default to form an interface identifier from
2043 the delegated prefixes. See also
<varname>Token=
</varname> setting below. Defaults to yes.
2049 <term><varname>Token=
</varname></term>
2051 <para>Specifies an optional address generation mode for assigning an address in each
2052 delegated prefix. Takes an IPv6 address. When set, the lower bits of the supplied address is
2053 combined with the upper bits of each delegatad prefix received from the WAN interface by the
2054 DHCPv6 Prefix Delegation to form a complete address. When
<varname>Assign=
</varname> is
2055 disabled, this setting is ignored. When unset, the EUI-
64 algorithm will be used to form
2056 addresses. Defaults to unset.
</para>
2061 <term><varname>ManageTemporaryAddress=
</varname></term>
2063 <para>As in the [Address] section, but defaults to true.
</para>
2070 <title>[IPv6AcceptRA] Section Options
</title>
2071 <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
2072 with the
<varname>IPv6AcceptRA=
</varname> setting described above:
</para>
2074 <variablelist class='network-directives'
>
2076 <term><varname>UseDNS=
</varname></term>
2078 <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
2079 precedence over any statically configured ones.
</para>
2081 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
2082 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2087 <term><varname>UseDomains=
</varname></term>
2089 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
2090 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
2091 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
2092 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
2093 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
2094 <literal>~
</literal>. Defaults to false.
</para>
2096 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
2097 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
2098 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
2099 single-label names.
</para>
2101 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
2102 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2107 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
2109 <para>The table identifier for the routes received in the Router Advertisement
2110 (a number between
1 and
4294967295, or
0 to unset).
2111 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
2117 <term><varname>UseAutonomousPrefix=
</varname></term>
2119 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
2120 precedence over any statically configured ones.
</para>
2125 <term><varname>UseOnLinkPrefix=
</varname></term>
2127 <para>When true (the default), the onlink prefix received in the Router Advertisement will be
2128 used and takes precedence over any statically configured ones.
</para>
2133 <term><varname>RouterDenyList=
</varname></term>
2135 <para>A whitespace-separated list of IPv6 router addresses. Any information advertised by
2136 the listed router is ignored.
</para>
2141 <term><varname>RouterAllowList=
</varname></term>
2143 <para>A whitespace-separated list of IPv6 router addresses. Only information advertised by
2144 the listed router is accepted. Note that if
<varname>RouterAllowList=
</varname> is
2145 configured then
<varname>RouterDenyList=
</varname> is ignored.
</para>
2150 <term><varname>PrefixDenyList=
</varname></term>
2152 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router
2153 advertisements in the list are ignored.
</para>
2158 <term><varname>PrefixAllowList=
</varname></term>
2160 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router
2161 advertisements in the list are allowed. Note that if
<varname>PrefixAllowList=
</varname> is
2162 configured then
<varname>PrefixDenyList=
</varname> is ignored.
</para>
2167 <term><varname>RouteDenyList=
</varname></term>
2169 <para>A whitespace-separated list of IPv6 route prefixes. IPv6 route prefixes supplied via
2170 router advertisements in the list are ignored.
</para>
2175 <term><varname>RouteAllowList=
</varname></term>
2177 <para>A whitespace-separated list of IPv6 route prefixes. IPv6 route prefixes supplied via
2178 router advertisements in the list are allowed. Note that if
<varname>RouteAllowList=
</varname> is
2179 configured then
<varname>RouteDenyList=
</varname> is ignored.
</para>
2184 <term><varname>DHCPv6Client=
</varname></term>
2186 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true or
2187 <literal>always
</literal>, the DHCPv6 client will be started when the RA has the managed or
2188 other information flag. If set to
<literal>always
</literal>, the DHCPv6 client will also be
2189 started in managed mode when neither managed nor other information flag is set in the RA.
2190 Defaults to true.
</para>
2197 <title>[DHCPServer] Section Options
</title>
2198 <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
2199 <varname>DHCPServer=
</varname> option described above:
</para>
2201 <variablelist class='network-directives'
>
2204 <term><varname>PoolOffset=
</varname></term>
2205 <term><varname>PoolSize=
</varname></term>
2207 <listitem><para>Configures the pool of addresses to hand out. The pool
2208 is a contiguous sequence of IP addresses in the subnet configured for
2209 the server address, which does not include the subnet nor the broadcast
2210 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
2211 from the start of subnet, or zero to use the default value.
2212 <varname>PoolSize=
</varname> takes the number of IP addresses in the
2213 pool or zero to use the default value. By default, the pool starts at
2214 the first address after the subnet address and takes up the rest of
2215 the subnet, excluding the broadcast address. If the pool includes
2216 the server address (the default), this is reserved and not handed
2217 out to clients.
</para></listitem>
2221 <term><varname>DefaultLeaseTimeSec=
</varname></term>
2222 <term><varname>MaxLeaseTimeSec=
</varname></term>
2224 <listitem><para>Control the default and maximum DHCP lease
2225 time to pass to clients. These settings take time values in seconds or
2226 another common time unit, depending on the suffix. The default
2227 lease time is used for clients that did not ask for a specific
2228 lease time. If a client asks for a lease time longer than the
2229 maximum lease time, it is automatically shortened to the
2230 specified time. The default lease time defaults to
1h, the
2231 maximum lease time to
12h. Shorter lease times are beneficial
2232 if the configuration data in DHCP leases changes frequently
2233 and clients shall learn the new settings with shorter
2234 latencies. Longer lease times reduce the generated DHCP
2235 network traffic.
</para></listitem>
2239 <term><varname>EmitDNS=
</varname></term>
2240 <term><varname>DNS=
</varname></term>
2242 <listitem><para><varname>EmitDNS=
</varname> takes a boolean. Configures whether the DHCP leases
2243 handed out to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>. The
2244 DNS servers to pass to clients may be configured with the
<varname>DNS=
</varname> option, which takes
2245 a list of IPv4 addresses. If the
<varname>EmitDNS=
</varname> option is enabled but no servers
2246 configured, the servers are automatically propagated from an
"uplink" interface that has appropriate
2247 servers set. The
"uplink" interface is determined by the default route of the system with the highest
2248 priority. Note that this information is acquired at the time the lease is handed out, and does not
2249 take uplink interfaces into account that acquire DNS server information at a later point. If no
2250 suitable uplinkg interface is found the DNS server data from
<filename>/etc/resolv.conf
</filename> is
2251 used. Also, note that the leases are not refreshed if the uplink network configuration changes. To
2252 ensure clients regularly acquire the most current uplink DNS server information, it is thus advisable
2253 to shorten the DHCP lease time via
<varname>MaxLeaseTimeSec=
</varname> described
2254 above.
</para></listitem>
2258 <term><varname>EmitNTP=
</varname></term>
2259 <term><varname>NTP=
</varname></term>
2260 <term><varname>EmitSIP=
</varname></term>
2261 <term><varname>SIP=
</varname></term>
2262 <term><varname>EmitPOP3=
</varname></term>
2263 <term><varname>POP3=
</varname></term>
2264 <term><varname>EmitSMTP=
</varname></term>
2265 <term><varname>SMTP=
</varname></term>
2266 <term><varname>EmitLPR=
</varname></term>
2267 <term><varname>LPR=
</varname></term>
2269 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname> settings
2270 described above, these settings configure whether and what server information for the indicate
2271 protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
2272 defaults apply as for
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname>.
</para></listitem>
2276 <term><varname>EmitRouter=
</varname></term>
2278 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
2279 setting described above, this setting configures whether the
2280 DHCP lease should contain the router option. The same syntax,
2281 propagation semantics and defaults apply as for
2282 <varname>EmitDNS=
</varname>.
</para></listitem>
2286 <term><varname>EmitTimezone=
</varname></term>
2287 <term><varname>Timezone=
</varname></term>
2289 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
2290 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
2291 <varname>Timezone=
</varname> setting takes a timezone string
2292 (such as
<literal>Europe/Berlin
</literal> or
2293 <literal>UTC
</literal>) to pass to clients. If no explicit
2294 timezone is set, the system timezone of the local host is
2295 propagated, as determined by the
2296 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
2300 <term><varname>SendOption=
</varname></term>
2302 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
2303 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2304 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
2305 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
2306 <literal>string
</literal>. Special characters in the data string may be escaped using
2307 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2308 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2309 then all options specified earlier are cleared. Defaults to unset.
</para>
2314 <term><varname>SendVendorOption=
</varname></term>
2316 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
2317 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2318 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
2319 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
2320 <literal>string
</literal>. Special characters in the data string may be escaped using
2321 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2322 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2323 then all options specified earlier are cleared. Defaults to unset.
</para>
2331 <title>[IPv6SendRA] Section Options
</title>
2332 <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
2333 to act as a router, if enabled via the
<varname>IPv6SendRA=
</varname> option described above. IPv6
2334 network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
2337 <variablelist class='network-directives'
>
2340 <term><varname>Managed=
</varname></term>
2341 <term><varname>OtherInformation=
</varname></term>
2343 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
2344 addresses on the network link when
<varname>Managed=
</varname>
2345 is set to
<literal>true
</literal> or if only additional network
2346 information can be obtained via DHCPv6 for the network link when
2347 <varname>OtherInformation=
</varname> is set to
2348 <literal>true
</literal>. Both settings default to
2349 <literal>false
</literal>, which means that a DHCPv6 server is not being
2350 used.
</para></listitem>
2354 <term><varname>RouterLifetimeSec=
</varname></term>
2356 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. When set to
2357 0, the host is not acting as a router. Defaults to
30 minutes.
</para>
2362 <term><varname>RouterPreference=
</varname></term>
2364 <listitem><para>Configures IPv6 router preference if
2365 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
2366 <literal>high
</literal>,
<literal>medium
</literal> and
2367 <literal>low
</literal>, with
<literal>normal
</literal> and
2368 <literal>default
</literal> added as synonyms for
2369 <literal>medium
</literal> just to make configuration easier. See
2370 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2371 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
2375 <term><varname>EmitDNS=
</varname></term>
2376 <term><varname>DNS=
</varname></term>
2378 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses that
2379 are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is
2380 true.
<varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that case
2381 the IPv6 link local address is distributed. If
<varname>DNS=
</varname> is empty, DNS servers are read
2382 from the [Network] section. If the [Network] section does not contain any DNS servers either, DNS
2383 servers from the uplink with the highest priority default route are used. When
2384 <varname>EmitDNS=
</varname> is false, no DNS server information is sent in Router Advertisement
2385 messages.
<varname>EmitDNS=
</varname> defaults to true.
</para></listitem>
2389 <term><varname>EmitDomains=
</varname></term>
2390 <term><varname>Domains=
</varname></term>
2392 <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
2393 <varname>EmitDomains=
</varname> is true. If
<varname>Domains=
</varname> is empty, DNS search domains
2394 are read from the [Network] section. If the [Network] section does not contain any DNS search domains
2395 either, DNS search domains from the uplink with the highest priority default route are used. When
2396 <varname>EmitDomains=
</varname> is false, no DNS search domain information is sent in Router
2397 Advertisement messages.
<varname>EmitDomains=
</varname> defaults to true.
</para></listitem>
2401 <term><varname>DNSLifetimeSec=
</varname></term>
2403 <listitem><para>Lifetime in seconds for the DNS server addresses listed
2404 in
<varname>DNS=
</varname> and search domains listed in
2405 <varname>Domains=
</varname>.
</para></listitem>
2412 <title>[IPv6Prefix] Section Options
</title>
2413 <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
2414 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink> for further
2417 <variablelist class='network-directives'
>
2420 <term><varname>AddressAutoconfiguration=
</varname></term>
2421 <term><varname>OnLink=
</varname></term>
2423 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
2424 autoconfigured with this prefix and whether the prefix can be used for
2425 onlink determination. Both settings default to
<literal>true
</literal>
2426 in order to ease configuration.
2431 <term><varname>Prefix=
</varname></term>
2433 <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
2434 IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
2435 <literal>/
</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
2436 prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
2437 prefix to another.
</para></listitem>
2441 <term><varname>PreferredLifetimeSec=
</varname></term>
2442 <term><varname>ValidLifetimeSec=
</varname></term>
2444 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2445 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
2446 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
2447 to
2592000 seconds (
30 days).
</para></listitem>
2451 <term><varname>Assign=
</varname></term>
2452 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
2459 <title>[IPv6RoutePrefix] Section Options
</title>
2460 <para>One or more [IPv6RoutePrefix] sections contain the IPv6
2461 prefix routes that are announced via Router Advertisements. See
2462 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2463 for further details.
</para>
2465 <variablelist class='network-directives'
>
2468 <term><varname>Route=
</varname></term>
2470 <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
2471 IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
2472 separated by a
<literal>/
</literal> character. Use multiple [IPv6PrefixRoutes] sections to configure
2473 multiple IPv6 prefix routes.
</para></listitem>
2477 <term><varname>LifetimeSec=
</varname></term>
2479 <listitem><para>Lifetime for the route prefix measured in
2480 seconds.
<varname>LifetimeSec=
</varname> defaults to
604800 seconds (one week).
2488 <title>[Bridge] Section Options
</title>
2489 <para>The [Bridge] section accepts the following keys:
</para>
2490 <variablelist class='network-directives'
>
2492 <term><varname>UnicastFlood=
</varname></term>
2494 <para>Takes a boolean. Controls whether the bridge should flood
2495 traffic for which an FDB entry is missing and the destination
2496 is unknown through this port. When unset, the kernel's default will be used.
2501 <term><varname>MulticastFlood=
</varname></term>
2503 <para>Takes a boolean. Controls whether the bridge should flood
2504 traffic for which an MDB entry is missing and the destination
2505 is unknown through this port. When unset, the kernel's default will be used.
2510 <term><varname>MulticastToUnicast=
</varname></term>
2512 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2513 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2514 When unset, the kernel's default will be used.
2519 <term><varname>NeighborSuppression=
</varname></term>
2521 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2522 this port. When unset, the kernel's default will be used.
2527 <term><varname>Learning=
</varname></term>
2529 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2530 this port. When unset, the kernel's default will be used.
2535 <term><varname>HairPin=
</varname></term>
2537 <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
2538 was received. When this flag is false, then the bridge will not forward traffic back out of the
2539 receiving port. When unset, the kernel's default will be used.
</para>
2543 <term><varname>UseBPDU=
</varname></term>
2545 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2546 processed by the bridge port. When unset, the kernel's default will be used.
</para>
2550 <term><varname>FastLeave=
</varname></term>
2552 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2553 traffic on a port that receives an IGMP Leave message. It is only used with
2554 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
2558 <term><varname>AllowPortToBeRoot=
</varname></term>
2560 <para>Takes a boolean. Configures whether a given port is allowed to
2561 become a root port. Only used when STP is enabled on the bridge.
2562 When unset, the kernel's default will be used.
</para>
2566 <term><varname>ProxyARP=
</varname></term>
2568 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2569 When unset, the kernel's default will be used.
</para>
2573 <term><varname>ProxyARPWiFi=
</varname></term>
2575 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2576 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
2577 When unset, the kernel's default will be used.
</para>
2581 <term><varname>MulticastRouter=
</varname></term>
2583 <para>Configures this port for having multicast routers attached. A port with a multicast
2584 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
2585 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
2586 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
2587 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
2588 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
2592 <term><varname>Cost=
</varname></term>
2594 <para>Sets the
"cost" of sending packets of this interface.
2595 Each port in a bridge may have a different speed and the cost
2596 is used to decide which link to use. Faster interfaces
2597 should have lower costs. It is an integer value between
1 and
2602 <term><varname>Priority=
</varname></term>
2604 <para>Sets the
"priority" of sending packets on this interface.
2605 Each port in a bridge may have a different priority which is used
2606 to decide which link to use. Lower value means higher priority.
2607 It is an integer value between
0 to
63. Networkd does not set any
2608 default, meaning the kernel default value of
32 is used.
</para>
2614 <title>[BridgeFDB] Section Options
</title>
2615 <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
2616 keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.
</para>
2618 <variablelist class='network-directives'
>
2620 <term><varname>MACAddress=
</varname></term>
2622 <para>As in the [Network] section. This key is mandatory.
</para>
2626 <term><varname>Destination=
</varname></term>
2628 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
2632 <term><varname>VLANId=
</varname></term>
2634 <para>The VLAN ID for the new static MAC table entry. If
2635 omitted, no VLAN ID information is appended to the new static MAC
2640 <term><varname>VNI=
</varname></term>
2642 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2643 the remote VXLAN tunnel endpoint. Takes a number in the range
1-
16777215.
2644 Defaults to unset.
</para>
2648 <term><varname>AssociatedWith=
</varname></term>
2650 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
2651 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
2652 <literal>use
</literal> means the address is in use. User space can use this option to
2653 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
2654 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
2655 means the address is associated with master devices fdb.
<literal>router
</literal> means
2656 the destination address is associated with a router. Note that it's valid if the referenced
2657 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
2663 <title>[BridgeMDB] Section Options
</title>
2664 <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
2665 keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.
</para>
2667 <variablelist class='network-directives'
>
2669 <term><varname>MulticastGroupAddress=
</varname></term>
2671 <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.
</para>
2675 <term><varname>VLANId=
</varname></term>
2677 <para>The VLAN ID for the new entry. Valid ranges are
0 (no VLAN) to
4094. Optional, defaults to
0.
</para>
2684 <title>[LLDP] Section Options
</title>
2685 <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
2687 <variablelist class='network-directives'
>
2689 <term><varname>MUDURL=
</varname></term>
2691 <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
2692 LLDP packets. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
2693 [DHCPv4] section described above.
</para>
2695 <para>The MUD URLs received via LLDP packets are saved and can be read using the
2696 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
2703 <title>[CAN] Section Options
</title>
2704 <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
2705 following keys:
</para>
2706 <variablelist class='network-directives'
>
2708 <term><varname>BitRate=
</varname></term>
2710 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
2711 be used here. Takes a number in the range
1.
.4294967295.
</para>
2715 <term><varname>SamplePoint=
</varname></term>
2717 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2718 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2722 <term><varname>DataBitRate=
</varname></term>
2723 <term><varname>DataSamplePoint=
</varname></term>
2725 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
2726 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
2730 <term><varname>FDMode=
</varname></term>
2732 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
2733 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
2734 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys.
</para>
2738 <term><varname>FDNonISO=
</varname></term>
2740 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
2741 interface. When unset, the kernel's default will be used.
</para>
2745 <term><varname>RestartSec=
</varname></term>
2747 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2748 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2749 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2750 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2751 automatic restart off. By default automatic restart is disabled.
</para>
2755 <term><varname>Termination=
</varname></term>
2757 <para>Takes a boolean. When
<literal>yes
</literal>, the termination resistor will be selected for
2758 the bias network. When unset, the kernel's default will be used.
</para>
2762 <term><varname>TripleSampling=
</varname></term>
2764 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2765 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
2769 <term><varname>BusErrorReporting=
</varname></term>
2771 <para>Takes a boolean. When
<literal>yes
</literal>, reporting of CAN bus errors is activated
2772 (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
2773 unable to send recessive bit, bus overload, active error announcement, error occurred on
2774 transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
2775 single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.
</para>
2779 <term><varname>ListenOnly=
</varname></term>
2781 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
2782 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
2783 bit. Listen-only mode is important to debug CAN networks without interfering with the
2784 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
2792 <title>[QDisc] Section Options
</title>
2793 <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).
</para>
2795 <variablelist class='network-directives'
>
2797 <term><varname>Parent=
</varname></term>
2799 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
2800 or
<literal>ingress
</literal>. This is mandatory.
</para>
2804 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2809 <title>[NetworkEmulator] Section Options
</title>
2810 <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
2811 can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
2812 applications, or limit the bandwidth usage of a particular service to simulate internet connections.
2815 <variablelist class='network-directives'
>
2816 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2817 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2820 <term><varname>DelaySec=
</varname></term>
2822 <para>Specifies the fixed amount of delay to be added to all packets going out of the
2823 interface. Defaults to unset.
</para>
2828 <term><varname>DelayJitterSec=
</varname></term>
2830 <para>Specifies the chosen delay to be added to the packets outgoing to the network
2831 interface. Defaults to unset.
</para>
2836 <term><varname>PacketLimit=
</varname></term>
2838 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
2839 An unsigned integer in the range
0–
4294967294. Defaults to
1000.
</para>
2844 <term><varname>LossRate=
</varname></term>
2846 <para>Specifies an independent loss probability to be added to the packets outgoing from the
2847 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2852 <term><varname>DuplicateRate=
</varname></term>
2854 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
2855 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2862 <title>[TokenBucketFilter] Section Options
</title>
2863 <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
2866 <variablelist class='network-directives'
>
2867 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2868 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2871 <term><varname>LatencySec=
</varname></term>
2873 <para>Specifies the latency parameter, which specifies the maximum amount of time a
2874 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
2879 <term><varname>LimitBytes=
</varname></term>
2881 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
2882 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
2883 respectively, to the base of
1024. Defaults to unset.
</para>
2888 <term><varname>BurstBytes=
</varname></term>
2890 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
2891 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
2892 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to
2898 <term><varname>Rate=
</varname></term>
2900 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
2901 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
2902 Defaults to unset.
</para>
2907 <term><varname>MPUBytes=
</varname></term>
2909 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
2910 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2911 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to zero.
</para>
2916 <term><varname>PeakRate=
</varname></term>
2918 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
2919 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2920 1000. Defaults to unset.
</para>
2925 <term><varname>MTUBytes=
</varname></term>
2927 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
2928 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
2929 Defaults to unset.
</para>
2936 <title>[PIE] Section Options
</title>
2937 <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
2938 controller-Enhanced (PIE).
</para>
2940 <variablelist class='network-directives'
>
2941 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2942 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2945 <term><varname>PacketLimit=
</varname></term>
2947 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2948 dropped. An unsigned integer in the range
1–
4294967294. Defaults to unset and kernel's default is used.
</para>
2955 <title>[FlowQueuePIE] Section Options
</title>
2956 <para>The
<literal>[FlowQueuePIE]
</literal> section manages the queueing discipline
2957 (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).
</para>
2959 <variablelist class='network-directives'
>
2960 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2961 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2964 <term><varname>PacketLimit=
</varname></term>
2966 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2967 dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2974 <title>[StochasticFairBlue] Section Options
</title>
2975 <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
2978 <variablelist class='network-directives'
>
2979 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2980 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2983 <term><varname>PacketLimit=
</varname></term>
2985 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
2986 incoming packets are dropped. An unsigned integer in the range
0–
4294967294. Defaults to unset and
2987 kernel's default is used.
</para>
2994 <title>[StochasticFairnessQueueing] Section Options
</title>
2995 <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
2996 fairness queueing (sfq).
</para>
2998 <variablelist class='network-directives'
>
2999 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3000 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3003 <term><varname>PerturbPeriodSec=
</varname></term>
3005 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
3012 <title>[BFIFO] Section Options
</title>
3013 <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
3016 <variablelist class='network-directives'
>
3017 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3018 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3021 <term><varname>LimitBytes=
</varname></term>
3023 <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
3024 in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
3025 reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
3026 as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
3027 kernel default is used.
</para>
3034 <title>[PFIFO] Section Options
</title>
3035 <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
3038 <variablelist class='network-directives'
>
3039 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3040 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3043 <term><varname>PacketLimit=
</varname></term>
3045 <para>Specifies the hard limit on the FIFO size in number of packets. The size limit (a buffer
3046 size) to prevent it from overflowing in case it is unable to dequeue packets as quickly as it
3047 receives them. When this limit is reached, incoming packets are dropped. An unsigned integer in the
3048 range
0–
4294967294. Defaults to unset and kernel's default is used.
</para>
3055 <title>[PFIFOHeadDrop] Section Options
</title>
3056 <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
3057 Head Drop (pfifo_head_drop).
</para>
3059 <variablelist class='network-directives'
>
3060 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3061 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3064 <term><varname>PacketLimit=
</varname></term>
3066 <para>As in [PFIFO] section.
</para></listitem>
3072 <title>[PFIFOFast] Section Options
</title>
3073 <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
3074 (pfifo_fast).
</para>
3076 <variablelist class='network-directives'
>
3077 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3078 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3083 <title>[CAKE] Section Options
</title>
3084 <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
3087 <variablelist class='network-directives'
>
3088 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3089 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3092 <term><varname>OverheadBytes=
</varname></term>
3094 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative. Takes
3095 an integer in the range from -
64 to
256. Defaults to unset and kernel's default is used.
</para>
3100 <term><varname>Bandwidth=
</varname></term>
3102 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
3103 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
3104 unset and kernel's default is used.
</para>
3111 <title>[ControlledDelay] Section Options
</title>
3112 <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
3113 controlled delay (CoDel).
</para>
3115 <variablelist class='network-directives'
>
3116 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3117 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3120 <term><varname>PacketLimit=
</varname></term>
3122 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3123 incoming packets are dropped. An unsigned integer in the range
0–
4294967294. Defaults to unset and
3124 kernel's default is used.
</para>
3129 <term><varname>TargetSec=
</varname></term>
3131 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
3132 Defaults to unset and kernel's default is used.
</para>
3137 <term><varname>IntervalSec=
</varname></term>
3139 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
3140 become too stale. Defaults to unset and kernel's default is used.
</para>
3145 <term><varname>ECN=
</varname></term>
3147 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3148 unset and kernel's default is used.
</para>
3153 <term><varname>CEThresholdSec=
</varname></term>
3155 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3156 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3163 <title>[DeficitRoundRobinScheduler] Section Options
</title>
3164 <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
3165 Robin Scheduler (DRR).
</para>
3167 <variablelist class='network-directives'
>
3168 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3169 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3174 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
3175 <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
3176 Robin Scheduler (DRR).
</para>
3178 <variablelist class='network-directives'
>
3179 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3180 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3183 <term><varname>QuantumBytes=
</varname></term>
3185 <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
3186 to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3187 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to the MTU of the
3196 <title>[EnhancedTransmissionSelection] Section Options
</title>
3197 <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
3198 Transmission Selection (ETS).
</para>
3200 <variablelist class='network-directives'
>
3201 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3202 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3205 <term><varname>Bands=
</varname></term>
3207 <para>Specifies the number of bands. An unsigned integer in the range
1–
16. This value has to be at
3208 least large enough to cover the strict bands specified through the
<varname>StrictBands=
</varname>
3209 and bandwidth-sharing bands specified in
<varname>QuantumBytes=
</varname>.
</para>
3214 <term><varname>StrictBands=
</varname></term>
3216 <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
3217 the range
1–
16.
</para>
3222 <term><varname>QuantumBytes=
</varname></term>
3224 <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
3225 suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3226 respectively, to the base of
1024. This setting can be specified multiple times. If an empty
3227 string is assigned, then the all previous assignments are cleared.
</para>
3232 <term><varname>PriorityMap=
</varname></term>
3234 <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
3235 separated list of numbers. The first number indicates which band the packets with priority
0 should
3236 be put to, the second is for priority
1, and so on. There can be up to
16 numbers in the list. If
3237 there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
3238 the last one. Each band number must be in the range
0.
.255. This setting can be specified multiple
3239 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
3246 <title>[GenericRandomEarlyDetection] Section Options
</title>
3247 <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
3248 Early Detection (GRED).
</para>
3250 <variablelist class='network-directives'
>
3251 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3252 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3255 <term><varname>VirtualQueues=
</varname></term>
3257 <para>Specifies the number of virtual queues. Takes a integer in the range
1-
16. Defaults to unset and kernel's default is used.
</para>
3262 <term><varname>DefaultVirtualQueue=
</varname></term>
3264 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
3265 Defaults to unset and kernel's default is used.
</para>
3270 <term><varname>GenericRIO=
</varname></term>
3272 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
3273 unset and kernel's default is used.
</para>
3280 <title>[FairQueueingControlledDelay] Section Options
</title>
3281 <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
3282 controlled delay (FQ-CoDel).
</para>
3284 <variablelist class='network-directives'
>
3285 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3286 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3289 <term><varname>PacketLimit=
</varname></term>
3291 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3292 dropped. Defaults to unset and kernel's default is used.
</para>
3297 <term><varname>MemoryLimitBytes=
</varname></term>
3299 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
3300 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3301 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
3306 <term><varname>Flows=
</varname></term>
3308 <para>Specifies the number of flows into which the incoming packets are classified.
3309 Defaults to unset and kernel's default is used.
</para>
3314 <term><varname>TargetSec=
</varname></term>
3316 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
3317 Defaults to unset and kernel's default is used.
</para>
3322 <term><varname>IntervalSec=
</varname></term>
3324 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
3325 become too stale. Defaults to unset and kernel's default is used.
</para>
3330 <term><varname>QuantumBytes=
</varname></term>
3332 <para>Specifies the number of bytes used as the
"deficit" in the fair queuing algorithm timespan.
3333 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3334 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
3339 <term><varname>ECN=
</varname></term>
3341 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3342 unset and kernel's default is used.
</para>
3347 <term><varname>CEThresholdSec=
</varname></term>
3349 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3350 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3357 <title>[FairQueueing] Section Options
</title>
3358 <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
3361 <variablelist class='network-directives'
>
3362 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3363 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3366 <term><varname>PacketLimit=
</varname></term>
3368 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3369 dropped. Defaults to unset and kernel's default is used.
</para>
3374 <term><varname>FlowLimit=
</varname></term>
3376 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
3377 unset and kernel's default is used.
</para>
3382 <term><varname>QuantumBytes=
</varname></term>
3384 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
3385 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3386 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
3387 default is used.
</para>
3392 <term><varname>InitialQuantumBytes=
</varname></term>
3394 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
3395 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
3396 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
3397 kernel's default is used.
</para>
3402 <term><varname>MaximumRate=
</varname></term>
3404 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
3405 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
3406 1000. Defaults to unset and kernel's default is used.
</para>
3411 <term><varname>Buckets=
</varname></term>
3413 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
3414 kernel's default is used.
</para>
3419 <term><varname>OrphanMask=
</varname></term>
3421 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
3422 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
3423 kernel's default is used.
</para>
3428 <term><varname>Pacing=
</varname></term>
3430 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
3431 default is used.
</para>
3436 <term><varname>CEThresholdSec=
</varname></term>
3438 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3439 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3446 <title>[TrivialLinkEqualizer] Section Options
</title>
3447 <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
3448 equalizer (teql).
</para>
3450 <variablelist class='network-directives'
>
3451 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3452 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3455 <term><varname>Id=
</varname></term>
3457 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
3458 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
3459 <constant>max_equalizers=N+
1</constant> option must be loaded before
3460 <command>systemd-networkd
</command> is started.
</para>
3467 <title>[HierarchyTokenBucket] Section Options
</title>
3468 <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
3469 bucket (htb).
</para>
3471 <variablelist class='network-directives'
>
3472 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3473 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3476 <term><varname>DefaultClass=
</varname></term>
3478 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
3479 to the class. Defaults to unset.
</para>
3484 <term><varname>RateToQuantum=
</varname></term>
3486 <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
3487 configured in
<varname>Rate=
</varname> by
<varname>RateToQuantum=
</varname>.
</para>
3494 <title>[HierarchyTokenBucketClass] Section Options
</title>
3495 <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
3498 <variablelist class='network-directives'
>
3499 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3500 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3503 <term><varname>Priority=
</varname></term>
3505 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
3506 priority field are tried for packets first.
</para>
3511 <term><varname>QuantumBytes=
</varname></term>
3513 <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
3514 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
3520 <term><varname>MTUBytes=
</varname></term>
3522 <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
3523 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
3528 <term><varname>OverheadBytes=
</varname></term>
3530 <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
3531 computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3532 Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
3537 <term><varname>Rate=
</varname></term>
3539 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
3540 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
3541 to the base of
1000. This setting is mandatory.
</para>
3546 <term><varname>CeilRate=
</varname></term>
3548 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
3549 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
3550 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
3556 <term><varname>BufferBytes=
</varname></term>
3558 <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
3559 with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
3560 to the base of
1024.
</para>
3565 <term><varname>CeilBufferBytes=
</varname></term>
3567 <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
3568 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3569 respectively, to the base of
1024.
</para>
3576 <title>[HeavyHitterFilter] Section Options
</title>
3577 <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
3580 <variablelist class='network-directives'
>
3581 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3582 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3585 <term><varname>PacketLimit=
</varname></term>
3587 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3588 incoming packets are dropped. An unsigned integer in the range
0–
4294967294. Defaults to unset and
3589 kernel's default is used.
</para>
3596 <title>[QuickFairQueueing] Section Options
</title>
3597 <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
3600 <variablelist class='network-directives'
>
3601 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3602 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3607 <title>[QuickFairQueueingClass] Section Options
</title>
3608 <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
3611 <variablelist class='network-directives'
>
3612 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3613 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3616 <term><varname>Weight=
</varname></term>
3618 <para>Specifies the weight of the class. Takes an integer in the range
1.
.1023. Defaults to
3619 unset in which case the kernel default is used.
</para>
3624 <term><varname>MaxPacketBytes=
</varname></term>
3626 <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the specified
3627 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. When unset,
3628 the kernel default is used.
</para>
3635 <title>[BridgeVLAN] Section Options
</title>
3636 <para>The [BridgeVLAN] section manages the VLAN ID configuration of a bridge port and accepts the
3637 following keys. Specify several [BridgeVLAN] sections to configure several VLAN entries. The
3638 <varname>VLANFiltering=
</varname> option has to be enabled, see the [Bridge] section in
3639 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3641 <variablelist class='network-directives'
>
3643 <term><varname>VLAN=
</varname></term>
3645 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
3646 from
1 to
4094.
</para>
3650 <term><varname>EgressUntagged=
</varname></term>
3652 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
3653 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
3654 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
3658 <term><varname>PVID=
</varname></term>
3660 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
3661 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
3662 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
3669 <title>Examples
</title>
3671 <title>Static network configuration
</title>
3673 <programlisting># /etc/systemd/network/
50-static.network
3678 Address=
192.168.0.15/
24
3679 Gateway=
192.168.0.1</programlisting>
3681 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
3682 specified gateway will be used for a default route.
</para>
3686 <title>DHCP on ethernet links
</title>
3688 <programlisting># /etc/systemd/network/
80-dhcp.network
3693 DHCP=yes
</programlisting>
3695 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
3696 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
3700 <title>IPv6 Prefix Delegation
</title>
3702 <programlisting># /etc/systemd/network/
55-ipv6-pd-upstream.network
3707 DHCP=ipv6
</programlisting>
3709 <programlisting># /etc/systemd/network/
56-ipv6-pd-downstream.network
3715 DHCPv6PrefixDelegation=yes
</programlisting>
3717 <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
3718 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
3719 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
3724 <title>A bridge with two enslaved links
</title>
3726 <programlisting># /etc/systemd/network/
25-bridge-static.network
3731 Address=
192.168.0.15/
24
3733 DNS=
192.168.0.1</programlisting>
3735 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
3740 Bridge=bridge0
</programlisting>
3742 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
3747 Bridge=bridge0
</programlisting>
3749 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
3750 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
3751 and network assigned, and a default route via the specified gateway will be
3752 added. The specified DNS server will be added to the global list of DNS resolvers.
3760 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
3776 EgressUntagged=
300-
400</programlisting>
3778 <para>This overrides the configuration specified in the previous example for the
3779 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
3780 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
3781 untagged when they leave on this interface. Untagged packets which arrive on this
3782 interface will be assigned VLAN ID
42.
</para>
3786 <title>Various tunnels
</title>
3788 <programlisting>/etc/systemd/network/
25-tunnels.network
3799 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
3805 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
3811 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
3817 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
3823 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
3824 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
3828 <title>A bond device
</title>
3830 <programlisting># /etc/systemd/network/
30-bond1.network
3838 <programlisting># /etc/systemd/network/
30-bond1.netdev
3844 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
3846 MACAddress=
52:
54:
00:e9:
64:
41
3852 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
3854 MACAddress=
52:
54:
00:e9:
64:
42
3860 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
3861 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
3862 will be used to acquire an address.
</para>
3866 <title>Virtual Routing and Forwarding (VRF)
</title>
3867 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
3868 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
3869 within the routing table defined during VRF creation. For kernels before
4.8 traffic
3870 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
3872 <programlisting># /etc/systemd/network/
25-vrf.network
3882 <title>MacVTap
</title>
3883 <para>This brings up a network interface
<literal>macvtap-test
</literal>
3884 and attaches it to
<literal>enp0s25
</literal>.
</para>
3885 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
3890 MACVTAP=macvtap-test
3895 <title>A Xfrm interface with physical underlying device.
</title>
3897 <programlisting># /etc/systemd/network/
27-xfrm.netdev
3902 InterfaceId=
7</programlisting>
3904 <programlisting># /etc/systemd/network/
27-eth0.network
3909 Xfrm=xfrm0
</programlisting>
3911 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
3912 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
3913 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
3919 <title>See Also
</title>
3921 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
3922 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
3923 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3924 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3925 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>