2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
6 <refentry id=
"systemd.network" conditional='ENABLE_NETWORKD'
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>systemd.network
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>systemd.network
</refentrytitle>
16 <manvolnum>5</manvolnum>
20 <refname>systemd.network
</refname>
21 <refpurpose>Network configuration
</refpurpose>
25 <para><filename><replaceable>network
</replaceable>.network
</filename></para>
29 <title>Description
</title>
31 <para>A plain ini-style text file that encodes network configuration for matching network
33 <citerefentry><refentrytitle>systemd-networkd
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
34 See
<citerefentry><refentrytitle>systemd.syntax
</refentrytitle><manvolnum>7</manvolnum></citerefentry>
35 for a general description of the syntax.
</para>
37 <para>The main network file must have the extension
<filename>.network
</filename>; other
38 extensions are ignored. Networks are applied to links whenever the links appear.
</para>
40 <para>The
<filename>.network
</filename> files are read from the files located in the system network
41 directories
<filename>/usr/lib/systemd/network
</filename> and
42 <filename>/usr/local/lib/systemd/network
</filename>, the volatile runtime network directory
43 <filename>/run/systemd/network
</filename> and the local administration network directory
44 <filename>/etc/systemd/network
</filename>. All configuration files are collectively sorted and
45 processed in alphanumeric order, regardless of the directories in which they live. However, files
46 with identical filenames replace each other. It is recommended that each filename is prefixed with
47 a number (e.g.
<filename>10-eth0.network
</filename>). Otherwise, the default
48 <filename>.network
</filename> files or those generated by
49 <citerefentry><refentrytitle>systemd-network-generator.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
50 may take precedence over user configured files. Files in
<filename>/etc/
</filename> have the highest
51 priority, files in
<filename>/run/
</filename> take precedence over files with the same name under
52 <filename>/usr/
</filename>. This can be used to override a system-supplied configuration file with
53 a local file if needed. As a special case, an empty file (file size
0) or symlink with the same
54 name pointing to
<filename>/dev/null
</filename> disables the configuration file entirely (it is
57 <para>Along with the network file
<filename>foo.network
</filename>, a
"drop-in" directory
58 <filename>foo.network.d/
</filename> may exist. All files with the suffix
59 <literal>.conf
</literal> from this directory will be merged in the alphanumeric order and parsed
60 after the main file itself has been parsed. This is useful to alter or add configuration settings,
61 without having to modify the main configuration file. Each drop-in file must have appropriate
62 section headers.
</para>
64 <para>In addition to
<filename>/etc/systemd/network
</filename>, drop-in
<literal>.d
</literal>
65 directories can be placed in
<filename>/usr/lib/systemd/network
</filename> or
66 <filename>/run/systemd/network
</filename> directories. Drop-in files in
67 <filename>/etc/
</filename> take precedence over those in
<filename>/run/
</filename> which in turn
68 take precedence over those in
<filename>/usr/lib/
</filename>. Drop-in files under any of these
69 directories take precedence over the main network file wherever located.
</para>
73 <title>[Match] Section Options
</title>
75 <para>The network file contains a [Match] section, which determines if a given network file may
76 be applied to a given interface; and a [Network] section specifying how the interface should be
77 configured. The first (in alphanumeric order) of the network files that matches a given interface
78 is applied, all later files are ignored, even if they match as well.
</para>
80 <para>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
82 the file will match all interfaces and
<command>systemd-networkd
</command> warns about that. Hint:
83 to avoid 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=
"kind" />
93 <xi:include href=
"systemd.link.xml" xpointer=
"property" />
96 <term><varname>Name=
</varname></term>
98 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
99 by the udev property
<literal>INTERFACE
</literal>, or device's alternative names. If the
100 list is prefixed with a
"!", the test is inverted.
</para>
105 <term><varname>WLANInterfaceType=
</varname></term>
107 <para>A whitespace-separated list of wireless network type. Supported values are
108 <literal>ad-hoc
</literal>,
<literal>station
</literal>,
<literal>ap
</literal>,
109 <literal>ap-vlan
</literal>,
<literal>wds
</literal>,
<literal>monitor
</literal>,
110 <literal>mesh-point
</literal>,
<literal>p2p-client
</literal>,
<literal>p2p-go
</literal>,
111 <literal>p2p-device
</literal>,
<literal>ocb
</literal>, and
<literal>nan
</literal>. If the
112 list is prefixed with a
"!", the test is inverted.
</para>
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.
</para>
125 <term><varname>BSSID=
</varname></term>
127 <para>A whitespace-separated list of hardware address of the currently connected wireless
128 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
129 <varname>MACAddress=
</varname>. This option may appear more than once, in which case the
130 lists are merged. If the empty string is assigned to this option, the list is reset.
</para>
134 <xi:include href=
"systemd.link.xml" xpointer=
"host" />
135 <xi:include href=
"systemd.link.xml" xpointer=
"virtualization" />
136 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-command-line" />
137 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-version" />
138 <xi:include href=
"systemd.link.xml" xpointer=
"credential" />
139 <xi:include href=
"systemd.link.xml" xpointer=
"architecture" />
140 <xi:include href=
"systemd.link.xml" xpointer=
"firmware" />
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>
158 <term><varname>MTUBytes=
</varname></term>
160 <para>The maximum transmission unit in bytes to set for the device. The usual suffixes K, M,
161 G, are supported and are understood to the base of
1024.
</para>
162 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen below
1280 (the
163 minimum MTU for IPv6) it will automatically be increased to this value.
</para>
168 <term><varname>ARP=
</varname></term>
170 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
171 for this interface is enabled. When unset, the kernel's default will be used.
</para>
172 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
173 interfaces atop a single lower-level physical interface, which will then only serve as a
174 link/
"bridge" device aggregating traffic to the same physical link and not participate in
175 the network otherwise. Defaults to unset.
</para>
180 <term><varname>Multicast=
</varname></term>
182 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults
188 <term><varname>AllMulticast=
</varname></term>
190 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the
191 network. This happens when multicast routing is enabled. Defaults to unset.
</para>
196 <term><varname>Promiscuous=
</varname></term>
198 <para>Takes a boolean. If set to true, promiscuous mode of the interface is enabled. Defaults
200 <para>If this is set to false for the underlying link of a
<literal>passthru
</literal> mode
201 MACVLAN/MACVTAP, the virtual interface will be created with the
<literal>nopromisc
</literal>
207 <term><varname>Unmanaged=
</varname></term>
209 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are made to bring up or
210 configure matching links, equivalent to when there are no matching network files. Defaults to
211 <literal>no
</literal>.
</para>
212 <para>This is useful for preventing later matching network files from interfering with
213 certain interfaces that are fully controlled by other applications.
</para>
218 <term><varname>Group=
</varname></term>
220 <para>Link groups are similar to port ranges found in managed switches. When network
221 interfaces are added to a numbered group, operations on all the interfaces from that group
222 can be performed at once. Takes an unsigned integer in the range
0…
2147483647. Defaults to
228 <term><varname>RequiredForOnline=
</varname></term>
230 <para>Takes a boolean or a minimum operational state and an optional maximum operational
232 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
233 for possible operational states. When
<literal>yes
</literal>, the network is deemed required
234 when determining whether the system is online (including when running
235 <command>systemd-networkd-wait-online
</command>). When
<literal>no
</literal>, the network is
236 ignored when determining the online state. When a minimum operational state and an optional
237 maximum operational state are set,
<literal>yes
</literal> is implied, and this controls the
238 minimum and maximum operational state required for the network interface to be considered
241 <para>Defaults to
<literal>yes
</literal> when
<varname>ActivationPolicy=
</varname> is not
242 set, or set to
<literal>up
</literal>,
<literal>always-up
</literal>, or
243 <literal>bound
</literal>. Defaults to
<literal>no
</literal> when
244 <varname>ActivationPolicy=
</varname> is set to
<literal>manual
</literal> or
245 <literal>down
</literal>. This is forced to
<literal>no
</literal> when
246 <varname>ActivationPolicy=
</varname> is set to
<literal>always-down
</literal>.
</para>
248 <para>The network will be brought up normally (as configured by
249 <varname>ActivationPolicy=
</varname>), but in the event that there is no address being
250 assigned by DHCP or the cable is not plugged in, the link will simply remain offline and be
251 skipped automatically by
<command>systemd-networkd-wait-online
</command> if
252 <literal>RequiredForOnline=no
</literal>.
</para>
257 <term><varname>RequiredFamilyForOnline=
</varname></term>
259 <para>Takes an address family. When specified, an IP address in the given family is deemed
260 required when determining whether the link is online (including when running
261 <command>systemd-networkd-wait-online
</command>). Takes one of
<literal>ipv4
</literal>,
262 <literal>ipv6
</literal>,
<literal>both
</literal>, or
<literal>any
</literal>. Defaults to
263 <literal>any
</literal>. Note that this option has no effect if
264 <literal>RequiredForOnline=no
</literal>, or if
<literal>RequiredForOnline=
</literal>
265 specifies a minimum operational state below
<literal>degraded
</literal>.
</para>
270 <term><varname>ActivationPolicy=
</varname></term>
272 <para>Specifies the policy for
<command>systemd-networkd
</command> managing the link
273 administrative state. Specifically, this controls how
<command>systemd-networkd
</command>
274 changes the network device's
<literal>IFF_UP
</literal> flag, which is sometimes
275 controlled by system administrators by running e.g.,
276 <command>ip link set dev eth0 up
</command> or
<command>ip link set dev eth0 down
</command>,
277 and can also be changed with
<command>networkctl up eth0
</command> or
278 <command>networkctl down eth0
</command>.
</para>
280 <para>Takes one of
<literal>up
</literal>,
<literal>always-up
</literal>,
281 <literal>manual
</literal>,
<literal>always-down
</literal>,
<literal>down
</literal>,
282 or
<literal>bound
</literal>. When
<literal>manual
</literal>,
283 <command>systemd-networkd
</command> will not change the link's admin state automatically;
284 the system administrator must bring the interface up or down manually, as desired. When
285 <literal>up
</literal> (the default) or
<literal>always-up
</literal>, or
286 <literal>down
</literal> or
<literal>always-down
</literal>,
287 <command>systemd-networkd
</command> will set the link up or down, respectively, when the
288 interface is (re)configured. When
<literal>always-up
</literal> or
289 <literal>always-down
</literal>,
<command>systemd-networkd
</command> will set the link up or
290 down, respectively, any time
<command>systemd-networkd
</command> detects a change in the
291 administrative state. When
<varname>BindCarrier=
</varname> is also set, this is automatically
292 set to
<literal>bound
</literal> and any other value is ignored.
</para>
294 <para>When the policy is set to
<literal>down
</literal> or
<literal>manual
</literal>, the
295 default value of
<varname>RequiredForOnline=
</varname> is
<literal>no
</literal>. When the
296 policy is set to
<literal>always-down
</literal>, the value of
297 <varname>RequiredForOnline=
</varname> forced to
<literal>no
</literal>.
</para>
299 <para>The administrative state is not the same as the carrier state, so using
300 <literal>always-up
</literal> does not mean the link will never lose carrier. The link carrier
301 depends on both the administrative state as well as the network device's physical connection.
302 However, to avoid reconfiguration failures, when using
<literal>always-up
</literal>,
303 <varname>IgnoreCarrierLoss=
</varname> is forced to true.
</para>
309 <xi:include href=
"systemd.link.xml" xpointer=
"sr-iov" />
312 <title>[Network] Section Options
</title>
314 <para>The [Network] section accepts the following keys:
</para>
316 <variablelist class='network-directives'
>
318 <term><varname>Description=
</varname></term>
320 <para>A description of the device. This is only used for presentation purposes.
</para>
325 <term><varname>DHCP=
</varname></term>
327 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
<literal>yes
</literal>,
328 <literal>no
</literal>,
<literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults to
329 <literal>no
</literal>.
</para>
331 <para>Note that DHCPv6 will by default be triggered by Router Advertisements, if reception is
332 enabled, regardless of this parameter. By explicitly enabling DHCPv6 support here, the DHCPv6
333 client will be started in the mode specified by the
<varname>WithoutRA=
</varname> setting in the
334 [DHCPv6] section, regardless of the presence of routers on the link, or what flags the routers
335 pass. See
<varname>IPv6AcceptRA=
</varname>.
</para>
337 <para>Furthermore, note that by default the domain name specified through DHCP is not used
338 for name resolution. See option
<option>UseDomains=
</option> below.
</para>
340 <para>See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the
341 DHCP client support.
</para>
346 <term><varname>DHCPServer=
</varname></term>
348 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started.
349 Defaults to
<literal>no
</literal>. Further settings for the DHCP server may be set in the
350 [DHCPServer] section described below.
</para>
355 <term><varname>LinkLocalAddressing=
</varname></term>
357 <para>Enables link-local address autoconfiguration. Accepts
<option>yes
</option>,
358 <option>no
</option>,
<option>ipv4
</option>, and
<option>ipv6
</option>. An IPv6 link-local
359 address is configured when
<option>yes
</option> or
<option>ipv6
</option>. An IPv4 link-local
360 address is configured when
<option>yes
</option> or
<option>ipv4
</option> and when DHCPv4
361 autoconfiguration has been unsuccessful for some time. (IPv4 link-local address
362 autoconfiguration will usually happen in parallel with repeated attempts to acquire a DHCPv4
365 <para>Defaults to
<option>no
</option> when
<varname>KeepMaster=
</varname> or
366 <varname>Bridge=
</varname> is set or when the specified
367 <varname>MACVLAN=
</varname>/
<varname>MACVTAP=
</varname> has
<varname>Mode=passthru
</varname>,
368 or
<option>ipv6
</option> otherwise.
</para>
373 <term><varname>IPv6LinkLocalAddressGenerationMode=
</varname></term>
375 <para>Specifies how IPv6 link-local address is generated. Takes one of
376 <literal>eui64
</literal>,
<literal>none
</literal>,
<literal>stable-privacy
</literal> and
377 <literal>random
</literal>. When unset,
<literal>stable-privacy
</literal> is used if
378 <varname>IPv6StableSecretAddress=
</varname> is specified, and if not,
379 <literal>eui64
</literal> is used. Note that if
<varname>LinkLocalAddressing=
</varname> is
380 <literal>no
</literal> or
<literal>ipv4
</literal>, then
381 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> will be ignored. Also, even if
382 <varname>LinkLocalAddressing=
</varname> is
<literal>yes
</literal> or
<literal>ipv6
</literal>,
383 setting
<varname>IPv6LinkLocalAddressGenerationMode=none
</varname>
384 disables to configure an IPv6 link-local address.
</para>
389 <term><varname>IPv6StableSecretAddress=
</varname></term>
391 <para>Takes an IPv6 address. The specified address will be used as a stable secret for
392 generating IPv6 link-local address. If this setting is specified, and
393 <varname>IPv6LinkLocalAddressGenerationMode=
</varname> is unset, then
394 <varname>IPv6LinkLocalAddressGenerationMode=stable-privacy
</varname> is implied.
395 If this setting is not specified, and
<literal>stable-privacy
</literal> is set to
396 <varname>IPv6LinkLocalAddressGenerationMode=
</varname>,
397 then a stable secret address will be generated from the local machine ID and the interface
403 <term><varname>IPv4LLStartAddress=
</varname></term>
405 <para>Specifies the first IPv4 link-local address to try. Takes an IPv4 address for example
406 169.254.1.2, from the link-local address range:
169.254.0.0/
16 except for
169.254.0.0/
24 and
407 169.254.255.0/
24. This setting may be useful if the device should always have the same address
408 as long as there is no address conflict. When unset, a random address will be automatically
409 selected. Defaults to unset.
</para>
414 <term><varname>IPv4LLRoute=
</varname></term>
416 <para>Takes a boolean. If set to true, sets up the route needed for non-IPv4LL hosts to
417 communicate with IPv4LL-only hosts. Defaults to false.
</para>
422 <term><varname>DefaultRouteOnDevice=
</varname></term>
424 <para>Takes a boolean. If set to true, sets up the IPv4 default route bound to the interface.
425 Defaults to false. This is useful when creating routes on point-to-point interfaces. This is
426 equivalent to e.g. the following,
427 <programlisting>ip route add default dev veth99
</programlisting>
429 <programlisting>[Route]
430 Gateway=
0.0.0.0</programlisting></para>
431 <para>Currently, there are no way to specify e.g., the table for the route configured by this
432 setting. To configure the default route with such an additional property, please use the
434 <programlisting>[Route]
436 Table=
1234</programlisting></para>
437 <para>If you'd like to create an IPv6 default route bound to the interface, please use the
439 <programlisting>[Route]
441 Table=
1234</programlisting></para>
446 <term><varname>LLMNR=
</varname></term>
448 <para>Takes a boolean or
<literal>resolve
</literal>. When true, enables
449 <ulink url=
"https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution
</ulink>
450 on the link. When set to
<literal>resolve
</literal>, only resolution is enabled, but not host
451 registration and announcement. Defaults to true. This setting is read by
452 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
458 <term><varname>MulticastDNS=
</varname></term>
460 <para>Takes a boolean or
<literal>resolve
</literal>. When true, enables
461 <ulink url=
"https://tools.ietf.org/html/rfc6762">Multicast DNS
</ulink> support on the link.
462 When set to
<literal>resolve
</literal>, only resolution is enabled, but not host or service
463 registration and announcement. Defaults to false. This setting is read by
464 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
470 <term><varname>DNSOverTLS=
</varname></term>
472 <para>Takes a boolean or
<literal>opportunistic
</literal>. When true, enables
473 <ulink url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink> support on the link.
474 When set to
<literal>opportunistic
</literal>, compatibility with non-DNS-over-TLS servers is
475 increased, by automatically turning off DNS-over-TLS servers in this case. This option
476 defines a per-interface setting for
477 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
478 global
<varname>DNSOverTLS=
</varname> option. Defaults to unset, and the global setting will
479 be used. This setting is read by
480 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
486 <term><varname>DNSSEC=
</varname></term>
488 <para>Takes a boolean or
<literal>allow-downgrade
</literal>. When true, enables
489 <ulink url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink> DNS validation support on the
490 link. When set to
<literal>allow-downgrade
</literal>, compatibility with non-DNSSEC capable
491 networks is increased, by automatically turning off DNSSEC in this case. This option defines
492 a per-interface setting for
493 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
494 global
<varname>DNSSEC=
</varname> option. Defaults to unset, and the global setting will be
495 used. This setting is read by
496 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
502 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
504 <para>A space-separated list of DNSSEC negative trust anchor domains. If specified and DNSSEC
505 is enabled, look-ups done via the interface's DNS server will be subject to the list of
506 negative trust anchors, and not require authentication for the specified domains, or anything
507 below it. Use this to disable DNSSEC authentication for specific private domains, that cannot
508 be proven valid using the Internet DNS hierarchy. Defaults to the empty list. This setting is
510 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
516 <term><varname>LLDP=
</varname></term>
518 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol
519 commonly implemented on professional routers and bridges which announces which physical port
520 a system is connected to, as well as other related data. Accepts a boolean or the special
521 value
<literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a
522 database of all LLDP neighbors maintained. If
<literal>routers-only
</literal> is set only
523 LLDP data of various types of routers is collected and LLDP data about other types of devices
524 ignored (such as stations, telephones and others). If false, LLDP reception is disabled.
525 Defaults to
<literal>routers-only
</literal>. Use
526 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
527 to query the collected neighbor data. LLDP is only available on Ethernet links. See
528 <varname>EmitLLDP=
</varname> below for enabling LLDP packet emission from the local system.
534 <term><varname>EmitLLDP=
</varname></term>
536 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the
537 special values
<literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
538 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission.
539 If not false, a short LLDP packet with information about the local system is sent out in
540 regular intervals on the link. The LLDP packet will contain information about the local
541 hostname, the local machine ID (as stored in
542 <citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
543 and the local interface name, as well as the pretty hostname of the system (as set in
544 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
545 LLDP emission is only available on Ethernet links. Note that this setting passes data
546 suitable for identification of host to the network and should thus not be enabled on
547 untrusted networks, where such identification data should not be made available. Use this
548 option to permit other systems to identify on which interfaces they are connected to this
549 system. The three special values control propagation of the LLDP packets. The
550 <literal>nearest-bridge
</literal> setting permits propagation only to the nearest connected
551 bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays,
552 but not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until
553 a customer bridge is reached. For details about these concepts, see
554 <ulink url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>.
555 Note that configuring this setting to true is equivalent to
556 <literal>nearest-bridge
</literal>, the recommended and most restricted level of propagation.
557 See
<varname>LLDP=
</varname> above for an option to enable LLDP reception.
</para>
562 <term><varname>BindCarrier=
</varname></term>
564 <para>A link name or a list of link names. When set, controls the behavior of the current
565 link. When all links in the list are in an operational down state, the current link is
566 brought down. When at least one link has carrier, the current interface is brought up.
</para>
568 <para>This forces
<varname>ActivationPolicy=
</varname> to be set to
<literal>bound
</literal>.
574 <term><varname>Address=
</varname></term>
576 <para>A static IPv4 or IPv6 address and its prefix length, separated by a
577 <literal>/
</literal> character. Specify this key more than once to configure several
578 addresses. The format of the address must be as described in
579 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
580 This is a short-hand for an [Address] section only containing an Address key (see below).
581 This option may be specified more than once.
</para>
583 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
584 <literal>::
</literal> (for IPv6), a new address range of the requested size is automatically
585 allocated from a system-wide pool of unused ranges. Note that the prefix length must be equal
586 or larger than
8 for IPv4, and
64 for IPv6. The allocated range is checked against all
587 current network interfaces and all known network configuration files to avoid address range
588 conflicts. The default system-wide pool consists of
192.168.0.0/
16,
172.16.0.0/
12 and
589 10.0.0.0/
8 for IPv4, and fd00::/
8 for IPv6. This functionality is useful to manage a large
590 number of dynamically created network interfaces with the same network configuration and
591 automatic address range assignment.
</para>
596 <term><varname>Gateway=
</varname></term>
598 <para>The gateway address, which must be in the format described in
599 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
600 This is a short-hand for a [Route] section only containing a
<varname>Gateway=
</varname> key.
601 This option may be specified more than once.
</para>
606 <term><varname>DNS=
</varname></term>
608 <para>A DNS server address, which must be in the format described in
609 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
610 This option may be specified more than once. Each address can optionally take a port number
611 separated with
<literal>:
</literal>, a network interface name or index separated with
612 <literal>%
</literal>, and a Server Name Indication (SNI) separated with
<literal>#
</literal>.
613 When IPv6 address is specified with a port number, then the address must be in the square
614 brackets. That is, the acceptable full formats are
615 <literal>111.222.333.444:
9953%ifname#example.com
</literal> for IPv4 and
616 <literal>[
1111:
2222::
3333]:
9953%ifname#example.com
</literal> for IPv6. If an empty string is
617 assigned, then the all previous assignments are cleared. This setting is read by
618 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
624 <term><varname>Domains=
</varname></term>
626 <para>A whitespace-separated list of domains which should be resolved using the DNS servers
627 on this link. Each item in the list should be a domain name, optionally prefixed with a tilde
628 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
629 domains without the prefix are called
"search domains" and are first used as search suffixes
630 for extending single-label hostnames (hostnames containing no dots) to become fully qualified
631 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
632 specified search domains are appended to it in turn, converting it into a fully qualified
633 domain name, until one of them may be successfully resolved.
</para>
635 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups
636 for hostnames ending in those domains (hence also single label names, if any
"search domains"
637 are listed), are routed to the DNS servers configured for this interface. The domain routing
638 logic is particularly useful on multi-homed hosts with DNS servers serving particular private
639 DNS zones on each interface.
</para>
641 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a
642 routing domain, the dot referring to the DNS root domain which is the implied suffix of all
643 valid DNS names) has special effect. It causes all DNS traffic which does not match another
644 configured domain routing entry to be routed to DNS servers specified for this interface.
645 This setting is useful to prefer a certain set of DNS servers if a link on which they are
646 connected is available.
</para>
648 <para>This setting is read by
649 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
650 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname>
652 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
653 Domain name routing has no equivalent in the traditional glibc API, which has no concept of
654 domain name servers limited to a specific link.
</para>
659 <term><varname>DNSDefaultRoute=
</varname></term>
661 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for
662 resolving domain names that do not match any link's configured
<varname>Domains=
</varname>
663 setting. If false, this link's configured DNS servers are never used for such domains, and
664 are exclusively used for resolving names that match at least one of the domains configured on
665 this link. If not specified defaults to an automatic mode: queries not matching any link's
666 configured domains will be routed to this link if it has no routing-only domains configured.
672 <term><varname>NTP=
</varname></term>
674 <para>An NTP server address (either an IP address, or a hostname). This option may be
675 specified more than once. This setting is read by
676 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
682 <term><varname>IPForward=
</varname></term>
684 <para>Configures IP packet forwarding for the system. If enabled, incoming packets on any
685 network interface will be forwarded to any other interfaces according to the routing table.
686 Takes a boolean, or the values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>, which only
687 enable IP packet forwarding for the specified address family. This controls the
688 <filename>net.ipv4.ip_forward
</filename> and
<filename>net.ipv6.conf.all.forwarding
</filename>
689 sysctl options of the network interface (see
690 <ulink url=
"https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl
</ulink>
691 for details about sysctl options). Defaults to
<literal>no
</literal>.
</para>
693 <para>Note: this setting controls a global kernel option, and does so one way only: if a
694 network that has this setting enabled is set up the global setting is turned on. However,
695 it is never turned off again, even after all networks with this setting enabled are shut
698 <para>To allow IP packet forwarding only between specific network interfaces use a firewall.
704 <term><varname>IPMasquerade=
</varname></term>
706 <para>Configures IP masquerading for the network interface. If enabled, packets forwarded
707 from the network interface will be appear as coming from the local host. Takes one of
708 <literal>ipv4
</literal>,
<literal>ipv6
</literal>,
<literal>both
</literal>, or
709 <literal>no
</literal>. Defaults to
<literal>no
</literal>. If enabled, this automatically sets
710 <varname>IPForward=
</varname> to one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal> or
711 <literal>yes
</literal>.
</para>
712 <para>Note. Any positive boolean values such as
<literal>yes
</literal> or
713 <literal>true
</literal> are now deprecated. Please use one of the values in the above.
</para>
718 <term><varname>IPv6PrivacyExtensions=
</varname></term>
720 <para>Configures use of stateless temporary addresses that change over time (see
721 <ulink url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
722 Privacy Extensions for Stateless Address Autoconfiguration in IPv6). Takes a boolean or the
723 special values
<literal>prefer-public
</literal> and
<literal>kernel
</literal>. When true,
724 enables the privacy extensions and prefers temporary addresses over public addresses. When
725 <literal>prefer-public
</literal>, enables the privacy extensions, but prefers public
726 addresses over temporary addresses. When false, the privacy extensions remain disabled. When
727 <literal>kernel
</literal>, the kernel's default setting will be left in place. When unspecified,
728 the value specified in the same setting in
729 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
730 which defaults to
<literal>no
</literal>, will be used.
</para>
735 <term><varname>IPv6AcceptRA=
</varname></term>
737 <para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
738 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they
739 may trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or
740 if no routers are found on the link. The default is to disable RA reception for bridge
741 devices or when IP forwarding is enabled, and to enable it otherwise. Cannot be enabled on
742 devices aggregated in a bond device or when link-local addressing is disabled.
</para>
744 <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA]
745 section, see below.
</para>
748 <ulink url=
"https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl
</ulink>
749 in the kernel documentation regarding
<literal>accept_ra
</literal>, but note that systemd's
750 setting of
<constant>1</constant> (i.e. true) corresponds to kernel's setting of
751 <constant>2</constant>.
</para>
753 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
754 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
755 RA protocol is used, and the kernel's own implementation remains disabled, since
756 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
757 and these are not available from the kernel if the kernel's own implementation is used.
763 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
765 <para>Configures the amount of IPv6 Duplicate Address Detection (DAD) probes to send. When
766 unset, the kernel's default will be used.
</para>
771 <term><varname>IPv6HopLimit=
</varname></term>
773 <para>Configures IPv6 Hop Limit. For each router that forwards the packet, the hop limit is
774 decremented by
1. When the hop limit field reaches zero, the packet is discarded. When unset,
775 the kernel's default will be used.
</para>
780 <term><varname>IPv4ReversePathFilter=
</varname></term>
782 <para>Configure IPv4 Reverse Path Filtering. If enabled, when an IPv4 packet is received, the machine will first check
783 whether the
<emphasis>source
</emphasis> of the packet would be routed through the interface it came in. If there is no
784 route to the source on that interface, the machine will drop the packet. Takes one of
785 <literal>no
</literal>,
<literal>strict
</literal>, or
<literal>loose
</literal>. When
<literal>no
</literal>,
786 no source validation will be done. When
<literal>strict
</literal>, mode each incoming packet is tested against the FIB and
787 if the incoming interface is not the best reverse path, the packet check will fail. By default failed packets are discarded.
788 When
<literal>loose
</literal>, mode each incoming packet's source address is tested against the FIB. The packet is dropped
789 only if the source address is not reachable via any interface on that router.
790 See
<ulink url=
"https://tools.ietf.org/html/rfc1027">RFC
3704</ulink>.
791 When unset, the kernel's default will be used.
</para>
796 <term><varname>IPv4AcceptLocal=
</varname></term>
798 <para>Takes a boolean. Accept packets with local source addresses. In combination with
799 suitable routing, this can be used to direct packets between two local interfaces over the
800 wire and have them accepted properly. When unset, the kernel's default will be used.
</para>
805 <term><varname>IPv4RouteLocalnet=
</varname></term>
807 <para>Takes a boolean. When true, the kernel does not consider loopback addresses as martian
808 source or destination while routing. This enables the use of
127.0.0.0/
8 for local routing
809 purposes. When unset, the kernel's default will be used.
</para>
814 <term><varname>IPv4ProxyARP=
</varname></term>
816 <para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one
817 host, usually a router, answers ARP requests intended for another machine. By
"faking" its
818 identity, the router accepts responsibility for routing packets to the
"real" destination.
819 See
<ulink url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>. When unset, the
820 kernel's default will be used.
</para>
825 <term><varname>IPv6ProxyNDP=
</varname></term>
827 <para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery Protocol)
828 is a technique for IPv6 to allow routing of addresses to a different destination when peers
829 expect them to be present on a certain physical link. In this case a router answers Neighbour
830 Advertisement messages intended for another machine by offering its own MAC address as
831 destination. Unlike proxy ARP for IPv4, it is not enabled globally, but will only send
832 Neighbour Advertisement messages for addresses in the IPv6 neighbor proxy table, which can
833 also be shown by
<command>ip -
6 neighbour show proxy
</command>. systemd-networkd will control
834 the per-interface `proxy_ndp` switch for each configured interface depending on this option.
835 When unset, the kernel's default will be used.
</para>
840 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
842 <para>An IPv6 address, for which Neighbour Advertisement messages will be proxied. This
843 option may be specified more than once. systemd-networkd will add the
844 <varname>IPv6ProxyNDPAddress=
</varname> entries to the kernel's IPv6 neighbor proxy table.
845 This setting implies
<varname>IPv6ProxyNDP=yes
</varname> but has no effect if
846 <varname>IPv6ProxyNDP=
</varname> has been set to false. When unset, the kernel's default will
852 <term><varname>IPv6SendRA=
</varname></term>
854 <para>Whether to enable or disable Router Advertisement sending on a link. Takes a boolean
855 value. When enabled, prefixes configured in [IPv6Prefix] sections and routes configured in
856 the [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA] section. If
857 <varname>DHCPPrefixDelegation=
</varname> is enabled, then the delegated prefixes are also
858 distributed. See
<varname>DCHPPrefixDelegation=
</varname> setting and the [IPv6SendRA],
859 [IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation] sections for more configuration
865 <term><varname>DHCPPrefixDelegation=
</varname></term>
867 <para>Takes a boolean value. When enabled, requests subnet prefixes on another link via the DHCPv6
868 protocol or via the
6RD option in the DHCPv4 protocol. An address within each delegated prefix will
869 be assigned, and the prefixes will be announced through IPv6 Router Advertisement if
870 <varname>IPv6SendRA=
</varname> is enabled. This behaviour can be configured in the
871 [DHCPPrefixDelegation] section. Defaults to disabled.
</para>
876 <term><varname>IPv6MTUBytes=
</varname></term>
878 <para>Configures IPv6 maximum transmission unit (MTU). An integer greater than or equal to
879 1280 bytes. When unset, the kernel's default will be used.
</para>
884 <term><varname>KeepMaster=
</varname></term>
886 <para>Takes a boolean value. When enabled, the current master interface index will not be
887 changed, and
<varname>BatmanAdvanced=
</varname>,
<varname>Bond=
</varname>,
888 <varname>Bridge=
</varname>, and
<varname>VRF=
</varname> settings are ignored. This may be
889 useful when a netdev with a master interface is created by another program, e.g.
890 <citerefentry><refentrytitle>systemd-nspawn
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
891 Defaults to false.
</para>
896 <term><varname>BatmanAdvanced=
</varname></term>
897 <term><varname>Bond=
</varname></term>
898 <term><varname>Bridge=
</varname></term>
899 <term><varname>VRF=
</varname></term>
901 <para>The name of the B.A.T.M.A.N. Advanced, bond, bridge, or VRF interface to add the link
903 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
909 <term><varname>IPoIB=
</varname></term>
910 <term><varname>IPVLAN=
</varname></term>
911 <term><varname>IPVTAP=
</varname></term>
912 <term><varname>MACsec=
</varname></term>
913 <term><varname>MACVLAN=
</varname></term>
914 <term><varname>MACVTAP=
</varname></term>
915 <term><varname>Tunnel=
</varname></term>
916 <term><varname>VLAN=
</varname></term>
917 <term><varname>VXLAN=
</varname></term>
918 <term><varname>Xfrm=
</varname></term>
920 <para>The name of an IPoIB, IPVLAN, IPVTAP, MACsec, MACVLAN, MACVTAP, tunnel, VLAN,
921 VXLAN, or Xfrm to be created on the link. See
922 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
923 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:
<literal>active-backup
</literal>,
932 <literal>balance-alb
</literal>, and
<literal>balance-tlb
</literal>. Defaults to false.
</para>
937 <term><varname>PrimarySlave=
</varname></term>
939 <para>Takes a boolean. Specifies which slave is the primary device. The specified device will
940 always be the active slave while it is available. Only when the primary is off-line will
941 alternate devices be used. This is useful when one slave is preferred over another, e.g.
942 when one slave has higher throughput than another. The
<literal>PrimarySlave=
</literal>
943 option is only valid for following modes:
<literal>active-backup
</literal>,
944 <literal>balance-alb
</literal>, and
<literal>balance-tlb
</literal>. Defaults to false.
</para>
949 <term><varname>ConfigureWithoutCarrier=
</varname></term>
951 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no
952 carrier. Defaults to false. If enabled, and the
<varname>IgnoreCarrierLoss=
</varname> setting
953 is not explicitly set, then it is enabled as well.
</para>
958 <term><varname>IgnoreCarrierLoss=
</varname></term>
960 <para>Takes a boolean or a timespan. When true,
<command>systemd-networkd
</command> retains
961 both the static and dynamic configuration of the interface even if its carrier is lost. When
962 false,
<command>systemd-networkd
</command> drops both the static and dynamic configuration of
963 the interface. When a timespan is specified,
<command>systemd-networkd
</command> waits for
964 the specified timespan, and ignores the carrier loss if the link regain its carrier within
965 the timespan. Setting
0 seconds is equivalent to
<literal>no
</literal>, and
966 <literal>infinite
</literal> is equivalent to
<literal>yes
</literal>.
</para>
968 <para>Setting a finite timespan may be useful when e.g. in the following cases:
971 <para>A wireless interface connecting to a network which has multiple access points with
972 the same SSID.
</para>
975 <para>Enslaving a wireless interface to a bond interface, which may disconnect from the
976 connected access point and causes its carrier to be lost.
</para>
979 <para>The driver of the interface resets when the MTU is changed.
</para>
984 <para>When
<varname>Bond=
</varname> is specified to a wireless interface, defaults to
3
985 seconds. When the DHCPv4 client is enabled and
<varname>UseMTU=
</varname> in the [DHCPv4]
986 section enabled, defaults to
5 seconds. Otherwise, defaults to the value specified with
987 <varname>ConfigureWithoutCarrier=
</varname>. When
<varname>ActivationPolicy=
</varname> is set
988 to
<literal>always-up
</literal>, this is forced to
<literal>yes
</literal>, and ignored any
989 user specified values.
</para>
994 <term><varname>KeepConfiguration=
</varname></term>
996 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
997 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
998 will not drop static addresses and routes on starting up process. When set to
999 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
1000 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
1001 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
1002 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
1003 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
1004 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
1005 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
1006 <literal>dhcp-on-stop
</literal> when
<command>systemd-networkd
</command> is running in
1007 initrd,
<literal>yes
</literal> when the root filesystem is a network filesystem, and
1008 <literal>no
</literal> otherwise.
</para>
1015 <title>[Address] Section Options
</title>
1017 <para>An [Address] section accepts the following keys. Specify several [Address] sections to
1018 configure several addresses.
</para>
1020 <variablelist class='network-directives'
>
1022 <term><varname>Address=
</varname></term>
1024 <para>As in the [Network] section. This setting is mandatory. Each [Address] section can
1025 contain one
<varname>Address=
</varname> setting.
</para>
1030 <term><varname>Peer=
</varname></term>
1032 <para>The peer address in a point-to-point connection. Accepts the same format as the
1033 <varname>Address=
</varname> setting.
</para>
1038 <term><varname>Broadcast=
</varname></term>
1040 <para>Takes an IPv4 address or boolean value. The address must be in the format described in
1041 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1042 If set to true, then the IPv4 broadcast address will be derived from the
1043 <varname>Address=
</varname> setting. If set to false, then the broadcast address will not be
1044 set. Defaults to true, except for wireguard interfaces, where it default to false.
</para>
1049 <term><varname>Label=
</varname></term>
1051 <para>Specifies the label for the IPv4 address. The label must be a
7-bit ASCII string with
1052 a length of
1…
15 characters. Defaults to unset.
</para>
1057 <term><varname>PreferredLifetime=
</varname></term>
1059 <para>Allows the default
"preferred lifetime" of the address to be overridden. Only three
1060 settings are accepted:
<literal>forever
</literal>,
<literal>infinity
</literal>, which is the
1061 default and means that the address never expires, and
<literal>0</literal>, which means that
1062 the address is considered immediately
"expired" and will not be used, unless explicitly
1063 requested. A setting of
<option>PreferredLifetime=
0</option> is useful for addresses which
1064 are added to be used only by a specific application, which is then configured to use them
1070 <term><varname>Scope=
</varname></term>
1072 <para>The scope of the address, which can be
<literal>global
</literal> (valid everywhere on
1073 the network, even through a gateway),
<literal>link
</literal> (only valid on this device,
1074 will not traverse a gateway) or
<literal>host
</literal> (only valid within the device itself,
1075 e.g.
127.0.0.1) or an integer in the range
0…
255. Defaults to
<literal>global
</literal>.
1081 <term><varname>RouteMetric=
</varname></term>
1083 <para>The metric of the prefix route, which is pointing to the subnet of the configured IP
1084 address, taking the configured prefix length into account. Takes an unsigned integer in the
1085 range
0…
4294967295. When unset or set to
0, the kernel's default value is used. This
1086 setting will be ignored when
<varname>AddPrefixRoute=
</varname> is false.
</para>
1091 <term><varname>HomeAddress=
</varname></term>
1093 <para>Takes a boolean. Designates this address the
"home address" as defined in
1094 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>. Supported only on IPv6.
1095 Defaults to false.
</para>
1100 <term><varname>DuplicateAddressDetection=
</varname></term>
1102 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
<literal>both
</literal>,
1103 or
<literal>none
</literal>. When
<literal>ipv4
</literal>, performs IPv4 Address Conflict
1104 Detection. See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>.
1105 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
1106 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>. Defaults to
1107 <literal>ipv4
</literal> for IPv4 link-local addresses,
<literal>ipv6
</literal> for IPv6
1108 addresses, and
<literal>none
</literal> otherwise.
</para>
1113 <term><varname>ManageTemporaryAddress=
</varname></term>
1115 <para>Takes a boolean. If true the kernel manage temporary addresses created from this one as
1116 template on behalf of Privacy Extensions
1117 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become active,
1118 the use_tempaddr sysctl setting has to be set to a value greater than zero. The given address
1119 needs to have a prefix length of
64. This flag allows using privacy extensions in a manually
1120 configured network, just like if stateless auto-configuration was active. Defaults to false.
1126 <term><varname>AddPrefixRoute=
</varname></term>
1128 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
1129 Defaults to true.
</para>
1134 <term><varname>AutoJoin=
</varname></term>
1136 <para>Takes a boolean. Joining multicast group on ethernet level via
1137 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
1138 IGMP snooping since the switch would not replicate multicast packets on ports that did not
1139 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
1140 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
1141 that enables them to do the required join. By extending
<command>ip address
</command> command
1142 with option
<literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS)
1143 vxlan interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
1144 Defaults to
<literal>no
</literal>.
</para>
1149 <term><varname>NetLabel=
</varname><replaceable>label
</replaceable></term>
1152 <para>This setting provides a method for integrating static and dynamic network configuration into
1153 Linux
<ulink url=
"https://docs.kernel.org/netlabel/index.html">NetLabel
</ulink> subsystem rules,
1154 used by
<ulink url=
"https://en.wikipedia.org/wiki/Linux_Security_Modules">Linux Security Modules
1155 (LSMs)
</ulink> for network access control. The label, with suitable LSM rules, can be used to
1156 control connectivity of (for example) a service with peers in the local network. At least with
1157 SELinux, only the ingress can be controlled but not egress. The benefit of using this setting is
1158 that it may be possible to apply interface independent part of NetLabel configuration at very early
1159 stage of system boot sequence, at the time when the network interfaces are not available yet, with
1161 project='man-pages'
><refentrytitle>netlabelctl
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1162 and the per-interface configuration with
<command>systemd-networkd
</command> once the interfaces
1163 appear later. Currently this feature is only implemented for SELinux.
</para>
1165 <para>The option expects a single NetLabel label. The label must conform to lexical restrictions of
1166 LSM labels. When an interface is configured with IP addresses, the addresses and subnetwork masks
1167 will be appended to the
<ulink
1168 url=
"https://github.com/SELinuxProject/selinux-notebook/blob/main/src/network_support.md">NetLabel
1169 Fallback Peer Labeling
</ulink> rules. They will be removed when the interface is
1170 deconfigured. Failures to manage the labels will be ignored.
</para>
1172 <para>Warning: Once labeling is enabled for network traffic, a lot of LSM access control points in
1173 Linux networking stack go from dormant to active. Care should be taken to avoid getting into a
1174 situation where for example remote connectivity is broken, when the security policy hasn't been
1175 updated to consider LSM per-packet access controls and no rules would allow any network
1176 traffic. Also note that additional configuration with
<citerefentry
1177 project='man-pages'
><refentrytitle>netlabelctl
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1181 <programlisting>[Address]
1182 NetLabel=system_u:object_r:localnet_peer_t:s0
</programlisting>
1184 With the example rules applying for interface
<literal>eth0
</literal>, when the interface is
1185 configured with an IPv4 address of
10.0.0.123/
8,
<command>systemd-networkd
</command> performs the
1186 equivalent of
<command>netlabelctl
</command> operation
1188 <programlisting>netlabelctl unlbl add interface eth0 address:
10.0.0.0/
8 label:system_u:object_r:localnet_peer_t:s0
</programlisting>
1190 and the reverse operation when the IPv4 address is deconfigured. The configuration can be used with
1191 LSM rules; in case of SELinux to allow a SELinux domain to receive data from objects of SELinux
1192 <literal>peer
</literal> class. For example:
1194 <programlisting>type localnet_peer_t;
1195 allow my_server_t localnet_peer_t:peer recv;
</programlisting>
1197 The effect of the above configuration and rules (in absence of other rules as may be the case) is
1198 to only allow
<literal>my_server_t
</literal> (and nothing else) to receive data from local subnet
1199 10.0.0.0/
8 of interface
<literal>eth0
</literal>.
1207 <title>[Neighbor] Section Options
</title>
1209 <para>A [Neighbor] section accepts the following keys. The neighbor section adds a permanent,
1210 static entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the
1211 links matched for the network. Specify several [Neighbor] sections to configure several static
1214 <variablelist class='network-directives'
>
1216 <term><varname>Address=
</varname></term>
1218 <para>The IP address of the neighbor.
</para>
1223 <term><varname>LinkLayerAddress=
</varname></term>
1225 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
1232 <title>[IPv6AddressLabel] Section Options
</title>
1234 <para>An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel]
1235 sections to configure several address labels. IPv6 address labels are used for address selection.
1236 See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>. Precedence is managed by
1237 userspace, and only the label itself is stored in the kernel.
</para>
1239 <variablelist class='network-directives'
>
1241 <term><varname>Label=
</varname></term>
1243 <para>The label for the prefix, an unsigned integer in the range
0…
4294967294.
0xffffffff is
1244 reserved. This setting is mandatory.
</para>
1249 <term><varname>Prefix=
</varname></term>
1251 <para>IPv6 prefix is an address with a prefix length, separated by a slash
1252 <literal>/
</literal> character. This setting is mandatory.
</para>
1259 <title>[RoutingPolicyRule] Section Options
</title>
1261 <para>An [RoutingPolicyRule] section accepts the following settings. Specify several
1262 [RoutingPolicyRule] sections to configure several rules.
</para>
1264 <variablelist class='network-directives'
>
1266 <term><varname>TypeOfService=
</varname></term>
1269 This specifies the Type of Service (ToS) field of packets to match;
1270 it takes an unsigned integer in the range
0…
255.
1271 The field can be used to specify precedence (the first
3 bits) and ToS (the next
3 bits).
1272 The field can be also used to specify Differentiated Services Code Point (DSCP) (the first
6 bits) and
1273 Explicit Congestion Notification (ECN) (the last
2 bits).
1274 See
<ulink url=
"https://en.wikipedia.org/wiki/Type_of_service">Type of Service
</ulink>
1275 and
<ulink url=
"https://en.wikipedia.org/wiki/Differentiated_services">Differentiated services
</ulink>
1282 <term><varname>From=
</varname></term>
1284 <para>Specifies the source address prefix to match. Possibly followed by a slash and the
1285 prefix length.
</para>
1290 <term><varname>To=
</varname></term>
1292 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the
1293 prefix length.
</para>
1298 <term><varname>FirewallMark=
</varname></term>
1300 <para>Specifies the iptables firewall mark value to match (a number in the range
1301 1…
4294967295). Optionally, the firewall mask (also a number between
1…
4294967295) can be
1302 suffixed with a slash (
<literal>/
</literal>), e.g.,
<literal>7/
255</literal>.
</para>
1307 <term><varname>Table=
</varname></term>
1309 <para>Specifies the routing table identifier to look up if the rule selector matches. Takes
1310 one of predefined names
<literal>default
</literal>,
<literal>main
</literal>, and
1311 <literal>local
</literal>, and names defined in
<varname>RouteTable=
</varname> in
1312 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1313 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1318 <term><varname>Priority=
</varname></term>
1320 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an integer in the
1321 range
0…
4294967295. Higher number means lower priority, and rules get processed in order of
1322 increasing number. Defaults to unset, and the kernel will pick a value dynamically.
</para>
1327 <term><varname>IncomingInterface=
</varname></term>
1329 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches
1330 packets originating from this host.
</para>
1335 <term><varname>OutgoingInterface=
</varname></term>
1337 <para>Specifies the outgoing device to match. The outgoing interface is only available for
1338 packets originating from local sockets that are bound to a device.
</para>
1343 <term><varname>SourcePort=
</varname></term>
1345 <para>Specifies the source IP port or IP port range match in forwarding information base
1346 (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
1347 Defaults to unset.
</para>
1352 <term><varname>DestinationPort=
</varname></term>
1354 <para>Specifies the destination IP port or IP port range match in forwarding information base
1355 (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
1356 Defaults to unset.
</para>
1361 <term><varname>IPProtocol=
</varname></term>
1363 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP
1364 protocol name such as
<literal>tcp
</literal>,
<literal>udp
</literal> or
1365 <literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
1366 <literal>tcp
</literal> or
<literal>17</literal> for
<literal>udp
</literal>. Defaults to unset.
1372 <term><varname>InvertRule=
</varname></term>
1374 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1379 <term><varname>Family=
</varname></term>
1381 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1382 <literal>both
</literal>. By default, the address family is determined by the address
1383 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1384 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1385 <literal>ipv4
</literal>.
</para>
1390 <term><varname>User=
</varname></term>
1392 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1398 <term><varname>SuppressPrefixLength=
</varname></term>
1400 <para>Takes a number
<replaceable>N
</replaceable> in the range
0…
128 and rejects routing
1401 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1407 <term><varname>SuppressInterfaceGroup=
</varname></term>
1409 <para>Takes an integer in the range
0…
2147483647 and rejects routing decisions that have
1410 an interface with the same group id. It has the same meaning as
1411 <option>suppress_ifgroup
</option> in
<command>ip rule
</command>. Defaults to unset.
</para>
1416 <term><varname>Type=
</varname></term>
1418 <para>Specifies Routing Policy Database (RPDB) rule type. Takes one of
1419 <literal>blackhole
</literal>,
<literal>unreachable
</literal> or
<literal>prohibit
</literal>.
1427 <title>[NextHop] Section Options
</title>
1429 <para>The [NextHop] section is used to manipulate entries in the kernel's
"nexthop" tables. The
1430 [NextHop] section accepts the following settings. Specify several [NextHop] sections to configure
1431 several hops.
</para>
1433 <variablelist class='network-directives'
>
1435 <term><varname>Id=
</varname></term>
1437 <para>The id of the next hop. Takes an integer in the range
1…
4294967295. If unspecified,
1438 then automatically chosen by kernel.
</para>
1443 <term><varname>Gateway=
</varname></term>
1445 <para>As in the [Network] section.
</para>
1450 <term><varname>Family=
</varname></term>
1452 <para>Takes one of the special values
<literal>ipv4
</literal> or
<literal>ipv6
</literal>.
1453 By default, the family is determined by the address specified in
1454 <varname>Gateway=
</varname>. If
<varname>Gateway=
</varname> is not specified, then defaults
1455 to
<literal>ipv4
</literal>.
</para>
1460 <term><varname>OnLink=
</varname></term>
1462 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1463 reachable directly by the current machine (i.e., attached to the local network), so that we
1464 can insert the nexthop in the kernel table without it being complained about. Defaults to
1465 <literal>no
</literal>.
</para>
1470 <term><varname>Blackhole=
</varname></term>
1472 <para>Takes a boolean. If enabled, packets to the corresponding routes are discarded
1473 silently, and
<varname>Gateway=
</varname> cannot be specified. Defaults to
1474 <literal>no
</literal>.
</para>
1479 <term><varname>Group=
</varname></term>
1481 <para>Takes a whitespace separated list of nexthop IDs. Each ID must be in the range
1482 1…
4294967295. Optionally, each nexthop ID can take a weight after a colon
1483 (
<literal><replaceable>id
</replaceable><optional>:
<replaceable>weight
</replaceable></optional></literal>).
1484 The weight must be in the range
1…
255. If the weight is not specified, then it is assumed
1485 that the weight is
1. This setting cannot be specified with
<varname>Gateway=
</varname>,
1486 <varname>Family=
</varname>,
<varname>Blackhole=
</varname>. This setting can be specified
1487 multiple times. If an empty string is assigned, then the all previous assignments are
1488 cleared. Defaults to unset.
</para>
1495 <title>[Route] Section Options
</title>
1497 <para>The [Route] section accepts the following settings. Specify several [Route] sections to
1498 configure several routes.
</para>
1500 <variablelist class='network-directives'
>
1502 <term><varname>Gateway=
</varname></term>
1504 <para>Takes the gateway address or the special values
<literal>_dhcp4
</literal> and
1505 <literal>_ipv6ra
</literal>. If
<literal>_dhcp4
</literal> or
<literal>_ipv6ra
</literal> is
1506 set, then the gateway address provided by DHCPv4 or IPv6 RA is used.
</para>
1511 <term><varname>GatewayOnLink=
</varname></term>
1513 <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
1514 reachable directly by the current machine (i.e., attached to the local network), so that we
1515 can insert the route in the kernel table without it being complained about. Defaults to
1516 <literal>no
</literal>.
</para>
1521 <term><varname>Destination=
</varname></term>
1523 <para>The destination prefix of the route. Possibly followed by a slash and the prefix
1524 length. If omitted, a full-length host route is assumed.
</para>
1529 <term><varname>Source=
</varname></term>
1531 <para>The source prefix of the route. Possibly followed by a slash and the prefix length. If
1532 omitted, a full-length host route is assumed.
</para>
1537 <term><varname>Metric=
</varname></term>
1539 <para>The metric of the route. Takes an unsigned integer in the range
0…
4294967295. Defaults
1540 to unset, and the kernel's default will be used.
</para>
1545 <term><varname>IPv6Preference=
</varname></term>
1547 <para>Specifies the route preference as defined in
1548 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink> for Router Discovery
1549 messages. Which can be one of
<literal>low
</literal> the route has a lowest priority,
1550 <literal>medium
</literal> the route has a default priority or
<literal>high
</literal> the
1551 route has a highest priority.
</para>
1556 <term><varname>Scope=
</varname></term>
1558 <para>The scope of the IPv4 route, which can be
<literal>global
</literal>,
1559 <literal>site
</literal>,
<literal>link
</literal>,
<literal>host
</literal>, or
1560 <literal>nowhere
</literal>:
</para>
1563 <para><literal>global
</literal> means the route can reach hosts more than one hop away.
1568 <para><literal>site
</literal> means an interior route in the local autonomous system.
1573 <para><literal>link
</literal> means the route can only reach hosts on the local network
1574 (one hop away).
</para>
1578 <para><literal>host
</literal> means the route will not leave the local machine (used for
1579 internal addresses like
127.0.0.1).
</para>
1583 <para><literal>nowhere
</literal> means the destination doesn't exist.
</para>
1587 <para>For IPv4 route, defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
1588 <literal>local
</literal> or
<literal>nat
</literal>, and
<literal>link
</literal> if
1589 <varname>Type=
</varname> is
<literal>broadcast
</literal>,
<literal>multicast
</literal>,
1590 <literal>anycast
</literal>, or
<literal>unicast
</literal>. In other cases,
1591 defaults to
<literal>global
</literal>. The value is not used for IPv6.
</para>
1596 <term><varname>PreferredSource=
</varname></term>
1598 <para>The preferred source address of the route. The address must be in the format described
1600 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
1606 <term><varname>Table=
</varname></term>
1608 <para>The table identifier for the route. Takes one of predefined names
1609 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
1610 defined in
<varname>RouteTable=
</varname> in
1611 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1612 or a number between
1 and
4294967295. The table can be retrieved using
1613 <command>ip route show table
<replaceable>num
</replaceable></command>. If unset and
1614 <varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1615 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1616 In other cases, defaults to
<literal>main
</literal>.
</para>
1621 <term><varname>HopLimit=
</varname></term>
1623 <para> Configures per route hop limit. See also
<varname>IPv6HopLimit=
</varname>.
</para>
1628 <term><varname>Protocol=
</varname></term>
1630 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special
1631 values
<literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1632 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1638 <term><varname>Type=
</varname></term>
1640 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1641 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1642 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1643 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1644 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e.
1645 a route indicating the path to take to a destination network address. If
1646 <literal>blackhole
</literal>, packets to the defined route are discarded silently. If
1647 <literal>unreachable
</literal>, packets to the defined route are discarded and the ICMP
1648 message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets to the
1649 defined route are discarded and the ICMP message
"Communication Administratively Prohibited"
1650 is generated. If
<literal>throw
</literal>, route lookup in the current routing table will
1651 fail and the route selection process will return to Routing Policy Database (RPDB). Defaults
1652 to
<literal>unicast
</literal>.
</para>
1657 <term><varname>InitialCongestionWindow=
</varname></term>
1659 <para>The TCP initial congestion window is used during the start of a TCP connection.
1660 During the start of a TCP session, when a client requests a resource, the server's initial
1661 congestion window determines how many packets will be sent during the initial burst of data
1662 without waiting for acknowledgement. Takes a number between
1 and
1023. Note that
100 is
1663 considered an extremely large value for this option. When unset, the kernel's default
1664 (typically
10) will be used.
</para>
1669 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1671 <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
1672 that can initially be buffered at one time on a connection. The sending host can send only
1673 that amount of data before waiting for an acknowledgment and window update from the
1674 receiving host. Takes a number between
1 and
1023. Note that
100 is considered an extremely
1675 large value for this option. When unset, the kernel's default will be used.
</para>
1680 <term><varname>QuickAck=
</varname></term>
1682 <para>Takes a boolean. When true, the TCP quick ACK mode for the route is enabled. When unset,
1683 the kernel's default will be used.
</para>
1688 <term><varname>FastOpenNoCookie=
</varname></term>
1690 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1691 When unset, the kernel's default will be used.
</para>
1696 <term><varname>TTLPropagate=
</varname></term>
1698 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1699 When unset, the kernel's default will be used.
</para>
1704 <term><varname>MTUBytes=
</varname></term>
1706 <para>The maximum transmission unit in bytes to set for the route. The usual suffixes K, M,
1707 G, are supported and are understood to the base of
1024.
</para>
1712 <term><varname>TCPAdvertisedMaximumSegmentSize=
</varname></term>
1714 <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G,
1715 are supported and are understood to the base of
1024. An unsigned integer in the range
1716 1…
4294967294. When unset, the kernel's default will be used.
</para>
1721 <term><varname>TCPCongestionControlAlgorithm=
</varname></term>
1723 <para>Specifies the TCP congestion control algorithm for the route. Takes a name of the algorithm,
1724 e.g.
<literal>bbr
</literal>,
<literal>dctcp
</literal>, or
<literal>vegas
</literal>. When unset,
1725 the kernel's default will be used.
</para>
1730 <term><varname>TCPRetransmissionTimeOutSec=
</varname></term>
1732 <para>Specifies the TCP Retransmission Time Out for the route. Takes time values in seconds.
1733 This value specifies the timeout of an alive TCP connection, when RTO retransmissions remain unacknowledged.
1734 When unset, the kernel's default will be used.
</para>
1739 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1741 <para>Configures multipath route. Multipath routing is the technique of using multiple
1742 alternative paths through a network. Takes gateway address. Optionally, takes a network
1743 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for this
1744 multipath route separated with whitespace. This setting can be specified multiple times. If
1745 an empty string is assigned, then the all previous assignments are cleared.
</para>
1750 <term><varname>NextHop=
</varname></term>
1752 <para>Specifies the nexthop id. Takes an unsigned integer in the range
1…
4294967295. If set,
1753 the corresponding [NextHop] section must be configured. Defaults to unset.
</para>
1760 <title>[DHCPv4] Section Options
</title>
1762 <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
1763 <varname>DHCP=
</varname> setting described above:
</para>
1765 <variablelist class='network-directives'
>
1767 <!-- DHCP packet contents -->
1770 <term><varname>SendHostname=
</varname></term>
1772 <para>When true (the default), the machine's hostname (or the value specified with
1773 <varname>Hostname=
</varname>, described below) will be sent to the DHCP server. Note that the
1774 hostname must consist only of
7-bit ASCII lower-case characters and no spaces or dots, and be
1775 formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option
1781 <term><varname>Hostname=
</varname></term>
1783 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's
1784 hostname. Note that the specified hostname must consist only of
7-bit ASCII lower-case
1785 characters and no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1790 <term><varname>MUDURL=
</varname></term>
1792 <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent
1793 to the DHCPv4 server. Takes a URL of length up to
255 characters. A superficial verification
1794 that the string is a valid URL will be performed. DHCPv4 clients are intended to have at most
1795 one MUD URL associated with them. See
1796 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
1798 <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers
1799 to advertise device specifications, including the intended communication patterns for their
1800 device when it connects to the network. The network can then use this to author a
1801 context-specific access policy, so the device functions only within those parameters.
</para>
1806 <term><varname>ClientIdentifier=
</varname></term>
1808 <para>The DHCPv4 client identifier to use. Takes one of
<option>mac
</option> or
1809 <option>duid
</option>. If set to
<option>mac
</option>, the MAC address of the link is used. If set
1810 to
<option>duid
</option>, an RFC4361-compliant Client ID, which is the combination of IAID and
1811 DUID, is used. IAID can be configured by
<varname>IAID=
</varname>. DUID can be configured by
1812 <varname>DUIDType=
</varname> and
<varname>DUIDRawData=
</varname>. Defaults to
1813 <option>duid
</option>.
</para>
1818 <term><varname>VendorClassIdentifier=
</varname></term>
1820 <para>The vendor class identifier used to identify vendor type and configuration.
</para>
1825 <term><varname>UserClass=
</varname></term>
1827 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or
1828 applications it represents. The information contained in this option is a string that
1829 represents the user class of which the client is a member. Each class sets an identifying
1830 string of information to be used by the DHCP service to classify clients. Takes a
1831 whitespace-separated list of strings.
</para>
1836 <term><varname>DUIDType=
</varname></term>
1838 <para>Override the global
<varname>DUIDType=
</varname> setting for this network. See
1839 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1840 for a description of possible values.
</para>
1845 <term><varname>DUIDRawData=
</varname></term>
1847 <para>Override the global
<varname>DUIDRawData=
</varname> setting for this network. See
1848 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1849 for a description of possible values.
</para>
1854 <term><varname>IAID=
</varname></term>
1856 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned
1862 <term><varname>Anonymize=
</varname></term>
1864 <para>Takes a boolean. When true, the options sent to the DHCP server will follow the
1865 <ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink> (Anonymity Profiles for
1866 DHCP Clients) to minimize disclosure of identifying information. Defaults to false.
</para>
1868 <para>This option should only be set to true when
<varname>MACAddressPolicy=
</varname> is set
1869 to
<option>random
</option> (see
1870 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
1873 <para>When true,
<varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1874 <varname>VendorClassIdentifier=
</varname>,
<varname>UserClass=
</varname>,
1875 <varname>RequestOptions=
</varname>,
<varname>SendOption=
</varname>,
1876 <varname>SendVendorOption=
</varname>, and
<varname>MUDURL=
</varname> are ignored.
</para>
1878 <para>With this option enabled DHCP requests will mimic those generated by Microsoft
1879 Windows, in order to reduce the ability to fingerprint and recognize installations. This
1880 means DHCP request sizes will grow and lease data will be more comprehensive than normally,
1881 though most of the requested data is not actually used.
</para>
1886 <term><varname>RequestOptions=
</varname></term>
1888 <para>Sets request options to be sent to the server in the DHCPv4 request options list. A
1889 whitespace-separated list of integers in the range
1…
254. Defaults to unset.
</para>
1894 <term><varname>SendOption=
</varname></term>
1896 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data
1897 type and data separated with a colon
1898 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1899 The option number must be an integer in the range
1…
254. The type takes one of
1900 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
1901 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
1902 string may be escaped using
1903 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1904 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
1905 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
1910 <term><varname>SendVendorOption=
</varname></term>
1912 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data
1913 type and data separated with a colon
1914 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1915 The option number must be an integer in the range
1…
254. The type takes one of
1916 <literal>uint8
</literal>,
<literal>uint16
</literal>,
<literal>uint32
</literal>,
1917 <literal>ipv4address
</literal>, or
<literal>string
</literal>. Special characters in the data
1918 string may be escaped using
1919 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1920 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1921 then all options specified earlier are cleared. Defaults to unset.
</para>
1926 <term><varname>IPServiceType=
</varname></term>
1928 <para>Takes one of the special values
<literal>none
</literal>,
<literal>CS6
</literal>, or
1929 <literal>CS4
</literal>. When
<literal>none
</literal> no IP service type is set to the packet
1930 sent from the DHCPv4 client. When
<literal>CS6
</literal> (network control) or
1931 <literal>CS4
</literal> (realtime), the corresponding service type will be set. Defaults to
1932 <literal>CS6
</literal>.
</para>
1937 <term><varname>SocketPriority=
</varname></term>
1939 <para>The Linux socket option
<constant>SO_PRIORITY
</constant> applied to the raw IP socket used for
1940 initial DHCPv4 messages. Unset by default. Usual values range from
0 to
6.
1941 More details about
<constant>SO_PRIORITY
</constant> socket option in
1942 <citerefentry project='man-pages'
><refentrytitle>socket
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
1943 Can be used in conjunction with [VLAN] section
<varname>EgressQOSMaps=
</varname> setting of .netdev
1944 file to set the
802.1Q VLAN ethernet tagged header priority, see
1945 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1950 <!-- How to use the DHCP lease -->
1953 <term><varname>Label=
</varname></term>
1955 <para>Specifies the label for the IPv4 address received from the DHCP server. The label must
1956 be a
7-bit ASCII string with a length of
1…
15 characters. Defaults to unset.
</para>
1961 <term><varname>UseDNS=
</varname></term>
1963 <para>When true (the default), the DNS servers received from the DHCP server will be used.
1966 <para>This corresponds to the
<option>nameserver
</option> option in
1967 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1973 <term><varname>RoutesToDNS=
</varname></term>
1975 <para>When true, the routes to the DNS servers received from the DHCP server will be
1976 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored. Defaults to
1982 <term><varname>UseNTP=
</varname></term>
1984 <para>When true (the default), the NTP servers received from the DHCP server will be used by
1985 <filename>systemd-timesyncd.service
</filename>.
</para>
1990 <term><varname>RoutesToNTP=
</varname></term>
1992 <para>When true, the routes to the NTP servers received from the DHCP server will be
1993 configured. When
<varname>UseNTP=
</varname> is disabled, this setting is ignored. Defaults to
1999 <term><varname>UseSIP=
</varname></term>
2001 <para>When true (the default), the SIP servers received from the DHCP server will be collected
2002 and made available to client programs.
</para>
2007 <term><varname>UseCaptivePortal=
</varname></term>
2009 <para>When true (the default), the captive portal advertised by the DHCP server will be recorded
2010 and made available to client programs and displayed in the networkctl status output per-link.
</para>
2015 <term><varname>UseMTU=
</varname></term>
2017 <para>When true, the interface maximum transmission unit from the DHCP server will be used on
2018 the current link. If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
2019 Defaults to false.
</para>
2021 <para>Note, some drivers will reset the interfaces if the MTU is changed. For such
2022 interfaces, please try to use
<varname>IgnoreCarrierLoss=
</varname> with a short timespan,
2023 e.g.
<literal>3 seconds
</literal>.
</para>
2028 <term><varname>UseHostname=
</varname></term>
2030 <para>When true (the default), the hostname received from the DHCP server will be set as the
2031 transient hostname of the system.
</para>
2036 <term><varname>UseDomains=
</varname></term>
2038 <para>Takes a boolean, or the special value
<option>route
</option>. When true, the domain name
2039 received from the DHCP server will be used as DNS search domain over this link, similarly to the
2040 effect of the
<option>Domains=
</option> setting. If set to
<option>route
</option>, the domain name
2041 received from the DHCP server will be used for routing DNS queries only, but not for searching,
2042 similarly to the effect of the
<option>Domains=
</option> setting when the argument is prefixed with
2043 <literal>~
</literal>. Defaults to false.
</para>
2045 <para>It is recommended to enable this option only on trusted networks, as setting this
2046 affects resolution of all hostnames, in particular of single-label names. It is generally
2047 safer to use the supplied domain only as routing domain, rather than as search domain, in
2048 order to not have it affect local resolution of single-label names.
</para>
2050 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
2051 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
2057 <term><varname>UseRoutes=
</varname></term>
2059 <para>When true (the default), the static routes will be requested from the DHCP server and
2060 added to the routing table with a metric of
1024, and a scope of
<option>global
</option>,
2061 <option>link
</option> or
<option>host
</option>, depending on the route's destination and
2062 gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the link's
2063 own address, the scope will be set to
<option>host
</option>. Otherwise if the gateway is null
2064 (a direct route), a
<option>link
</option> scope will be used. For anything else, scope
2065 defaults to
<option>global
</option>.
</para>
2070 <term><varname>RouteMetric=
</varname></term>
2072 <para>Set the routing metric for routes specified by the DHCP server (including the prefix
2073 route added for the specified prefix). Takes an unsigned integer in the range
0…
4294967295.
2074 Defaults to
1024.
</para>
2079 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
2081 <para>The table identifier for DHCP routes. Takes one of predefined names
2082 <literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>, and names
2083 defined in
<varname>RouteTable=
</varname> in
2084 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2085 or a number between
1…
4294967295.
</para>
2087 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
2088 used when this parameter is not specified.
</para>
2093 <term><varname>RouteMTUBytes=
</varname></term>
2095 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further
2101 <term><varname>QuickAck=
</varname></term>
2103 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
2104 the acquired DHCPv4 lease. When unset, the kernel's default will be used.
</para>
2109 <term><varname>InitialCongestionWindow=
</varname></term>
2111 <para>As in the [Route] section.
</para>
2116 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
2118 <para>As in the [Route] section.
</para>
2123 <term><varname>UseGateway=
</varname></term>
2125 <para>When true, the gateway will be requested from the DHCP server and added to the routing
2126 table with a metric of
1024, and a scope of
<option>link
</option>. When unset, the value
2127 specified with
<varname>UseRoutes=
</varname> is used.
</para>
2132 <term><varname>UseTimezone=
</varname></term>
2133 <listitem><para>When true, the timezone received from the DHCP server will be set as timezone
2134 of the local system. Defaults to false.
</para></listitem>
2138 <term><varname>Use6RD=
</varname></term>
2140 <para>When true, subnets of the received IPv6 prefix are assigned to downstream interfaces
2141 which enables
<varname>DHCPPrefixDelegation=
</varname>. See also
2142 <varname>DHCPPrefixDelegation=
</varname> in the [Network] section, the [DHCPPrefixDelegation]
2143 section, and
<ulink url=
"https://tools.ietf.org/html/rfc5969">RFC
5969</ulink>. Defaults to
2149 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
2151 <para>Allows one to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease
2152 lifetime. Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal>. If
2153 specified, the acquired address never expires. Defaults to unset.
</para>
2157 <!-- How to communicate with the server -->
2160 <term><varname>RequestBroadcast=
</varname></term>
2162 <para>Request the server to use broadcast messages before the IP address has been configured.
2163 This is necessary for devices that cannot receive RAW packets, or that cannot receive packets
2164 at all before an IP address has been configured. On the other hand, this must not be enabled
2165 on networks where broadcasts are filtered out.
</para>
2170 <term><varname>MaxAttempts=
</varname></term>
2172 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
2173 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>. Note that the
2174 time between retries is increased exponentially, up to approximately one per minute, so the
2175 network will not be overloaded even if this number is high. The default is suitable in most
2176 circumstances.
</para>
2181 <term><varname>ListenPort=
</varname></term>
2183 <para>Set the port from which the DHCP client packets originate.
</para>
2188 <term><varname>DenyList=
</varname></term>
2190 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2191 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are rejected.
2192 Note that if
<varname>AllowList=
</varname> is configured then
<varname>DenyList=
</varname> is
2198 <term><varname>AllowList=
</varname></term>
2200 <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
2201 prefix length after
<literal>/
</literal>. DHCP offers from servers in the list are accepted.
2207 <term><varname>SendRelease=
</varname></term>
2209 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops. Defaults to
2215 <term><varname>SendDecline=
</varname></term>
2217 <para>A boolean. When true,
<command>systemd-networkd
</command> performs IPv4 Duplicate
2218 Address Detection to the acquired address by the DHCPv4 client. If duplicate is detected,
2219 the DHCPv4 client rejects the address by sending a
<constant>DHCPDECLINE
</constant> packet to
2220 the DHCP server, and tries to obtain an IP address again. See
2221 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5227</ulink>. Defaults to false.
</para>
2226 <term><varname>NetLabel=
</varname></term>
2228 <para>This applies the NetLabel for the addresses received with DHCP, like
2229 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
2230 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
2237 <title>[DHCPv6] Section Options
</title>
2239 <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
2240 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
2243 <variablelist class='network-directives'
>
2245 <!-- DHCP packet contents -->
2248 <term><varname>MUDURL=
</varname></term>
2249 <term><varname>IAID=
</varname></term>
2250 <term><varname>DUIDType=
</varname></term>
2251 <term><varname>DUIDRawData=
</varname></term>
2252 <term><varname>RequestOptions=
</varname></term>
2254 <para>As in the [DHCPv4] section.
</para>
2259 <term><varname>SendOption=
</varname></term>
2261 <para>As in the [DHCPv4] section, however because DHCPv6 uses
16-bit fields to store option
2262 numbers, the option number is an integer in the range
1…
65536.
</para>
2267 <term><varname>SendVendorOption=
</varname></term>
2269 <para>Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier,
2270 DHCP option number, data type, and data separated with a colon
2271 (
<literal><replaceable>enterprise identifier
</replaceable>:
<replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2272 Enterprise identifier is an unsigned integer in the range
1…
4294967294. The option number
2273 must be an integer in the range
1…
254. Data type takes one of
<literal>uint8
</literal>,
2274 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
2275 <literal>ipv6address
</literal>, or
<literal>string
</literal>. Special characters in the data
2276 string may be escaped using
2277 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2278 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2279 specified, then all options specified earlier are cleared. Defaults to unset.
</para>
2284 <term><varname>UserClass=
</varname></term>
2286 <para>A DHCPv6 client can use User Class option to identify the type or category of user or
2287 applications it represents. The information contained in this option is a string that
2288 represents the user class of which the client is a member. Each class sets an identifying
2289 string of information to be used by the DHCP service to classify clients. Special characters
2290 in the data string may be escaped using
2291 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2292 escapes
</ulink>. This setting can be specified multiple times. If an empty string is
2293 specified, then all options specified earlier are cleared. Takes a whitespace-separated list
2294 of strings. Note that currently
<constant>NUL
</constant> bytes are not allowed.
</para>
2299 <term><varname>VendorClass=
</varname></term>
2301 <para>A DHCPv6 client can use VendorClass option to identify the vendor that manufactured the
2302 hardware on which the client is running. The information contained in the data area of this
2303 option is contained in one or more opaque fields that identify details of the hardware
2304 configuration. Takes a whitespace-separated list of strings.
</para>
2309 <term><varname>PrefixDelegationHint=
</varname></term>
2311 <para>Takes an IPv6 address with prefix length in the same format as the
2312 <varname>Address=
</varname> in the [Network] section. The DHCPv6 client will include a prefix
2313 hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
2314 1…
128. Defaults to unset.
</para>
2319 <term><varname>RapidCommit=
</varname></term>
2321 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server
2322 through a rapid two-message exchange (solicit and reply). When the rapid commit option is set by
2323 both the DHCPv6 client and the DHCPv6 server, the two-message exchange is used. Otherwise, the
2324 four-message exchange (solicit, advertise, request, and reply) is used. The two-message exchange
2325 provides faster client configuration. See
2326 <ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
2327 Defaults to true, and the two-message exchange will be used if the server support it.
</para>
2331 <!-- How to use the DHCP lease -->
2334 <term><varname>UseAddress=
</varname></term>
2336 <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
2342 <term><varname>UseCaptivePortal=
</varname></term>
2344 <para>When true (the default), the captive portal advertised by the DHCPv6 server will be recorded
2345 and made available to client programs and displayed in the networkctl status output per-link.
</para>
2350 <term><varname>UseDelegatedPrefix=
</varname></term>
2352 <para>When true (the default), the client will request the DHCPv6 server to delegate
2353 prefixes. If the server provides prefixes to be delegated, then subnets of the prefixes are
2354 assigned to the interfaces that have
<varname>DHCPPrefixDelegation=yes
</varname>.
2355 See also the
<varname>DHCPPrefixDelegation=
</varname> setting in the [Network] section,
2356 settings in the [DHCPPrefixDelegation] section, and
2357 <ulink url=
"https://www.rfc-editor.org/rfc/rfc8415.html#section-6.3">RFC
8415</ulink>.
2363 <term><varname>UseDNS=
</varname></term>
2364 <term><varname>UseNTP=
</varname></term>
2365 <term><varname>UseHostname=
</varname></term>
2366 <term><varname>UseDomains=
</varname></term>
2367 <term><varname>NetLabel=
</varname></term>
2368 <term><varname>SendRelease=
</varname></term>
2370 <para>As in the [DHCPv4] section.
</para>
2374 <!-- How to communicate with the server -->
2377 <term><varname>WithoutRA=
</varname></term>
2379 <para>Allows DHCPv6 client to start without router advertisements's
2380 <literal>managed
</literal> or
<literal>other configuration
</literal> flag. Takes one of
2381 <literal>no
</literal>,
<literal>solicit
</literal>, or
2382 <literal>information-request
</literal>. If this is not specified,
2383 <literal>solicit
</literal> is used when
<varname>DHCPPrefixDelegation=
</varname> is enabled
2384 and
<varname>UplinkInterface=:self
</varname> is specified in the [DHCPPrefixDelegation]
2385 section. Otherwise, defaults to
<literal>no
</literal>, and the DHCPv6 client will be started
2386 when an RA is received. See also the
<varname>DHCPv6Client=
</varname> setting in the
2387 [IPv6AcceptRA] section.
</para>
2394 <title>[DHCPPrefixDelegation] Section Options
</title>
2395 <para>The [DHCPPrefixDelegation] section configures subnet prefixes of the delegated prefixes
2396 acquired by a DHCPv6 client or by a DHCPv4 client through the
6RD option on another interface.
2397 The settings in this section are used only when the
<varname>DHCPPrefixDelegation=
</varname>
2398 setting in the [Network] section is enabled.
</para>
2400 <variablelist class='network-directives'
>
2402 <term><varname>UplinkInterface=
</varname></term>
2404 <para>Specifies the name or the index of the uplink interface, or one of the special values
2405 <literal>:self
</literal> and
<literal>:auto
</literal>. When
<literal>:self
</literal>, the
2406 interface itself is considered the uplink interface, and
2407 <varname>WithoutRA=solicit
</varname> is implied if the setting is not explicitly specified.
2408 When
<literal>:auto
</literal>, the first link which acquired prefixes to be delegated from
2409 the DHCPv6 or DHCPv4 server is selected. Defaults to
<literal>:auto
</literal>.
</para>
2414 <term><varname>SubnetId=
</varname></term>
2416 <para>Configure a specific subnet ID on the interface from a (previously) received prefix
2417 delegation. You can either set
"auto" (the default) or a specific subnet ID (as defined in
2418 <ulink url=
"https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC
4291</ulink>, section
2419 2.5.4), in which case the allowed value is hexadecimal, from
0 to
0x7fffffffffffffff
2425 <term><varname>Announce=
</varname></term>
2427 <para>Takes a boolean. When enabled, and
<varname>IPv6SendRA=
</varname> in [Network] section
2428 is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
2429 This setting will be ignored when the
<varname>DHCPPrefixDelegation=
</varname> setting is
2430 enabled on the upstream interface. Defaults to yes.
</para>
2435 <term><varname>Assign=
</varname></term>
2437 <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
2438 are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
2439 interface), the EUI-
64 algorithm will be used by default to form an interface identifier from
2440 the delegated prefixes. See also
<varname>Token=
</varname> setting below. Defaults to yes.
2446 <term><varname>Token=
</varname></term>
2448 <para>Specifies an optional address generation mode for assigning an address in each
2449 delegated prefix. This accepts the same syntax as
<varname>Token=
</varname> in the
2450 [IPv6AcceptRA] section. If
<varname>Assign=
</varname> is set to false, then this setting will
2451 be ignored. Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
2456 <term><varname>ManageTemporaryAddress=
</varname></term>
2458 <para>As in the [Address] section, but defaults to true.
</para>
2463 <term><varname>RouteMetric=
</varname></term>
2465 <para>The metric of the route to the delegated prefix subnet. Takes an unsigned integer in
2466 the range
0…
4294967295. When set to
0, the kernel's default value is used. Defaults to
256.
2472 <term><varname>NetLabel=
</varname></term>
2474 <para>This applies the NetLabel for the addresses received with DHCP, like
2475 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
2476 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
2483 <title>[IPv6AcceptRA] Section Options
</title>
2484 <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
2485 with the
<varname>IPv6AcceptRA=
</varname> setting described above:
</para>
2487 <variablelist class='network-directives'
>
2489 <term><varname>Token=
</varname></term>
2491 <para>Specifies an optional address generation mode for the Stateless Address
2492 Autoconfiguration (SLAAC). The following values are supported:
</para>
2496 <term><option>eui64
</option></term>
2499 The EUI-
64 algorithm will be used to generate an address for that prefix. Only
2500 supported by Ethernet or InfiniBand interfaces.
2505 <term><option>static:
<replaceable>ADDRESS
</replaceable></option></term>
2508 An IPv6 address must be specified after a colon (
<literal>:
</literal>), and the
2509 lower bits of the supplied address are combined with the upper bits of a prefix
2510 received in a Router Advertisement (RA) message to form a complete address. Note
2511 that if multiple prefixes are received in an RA message, or in multiple RA messages,
2512 addresses will be formed from each of them using the supplied address. This mode
2513 implements SLAAC but uses a static interface identifier instead of an identifier
2514 generated by using the EUI-
64 algorithm. Because the interface identifier is static,
2515 if Duplicate Address Detection detects that the computed address is a duplicate
2516 (in use by another node on the link), then this mode will fail to provide an address
2517 for that prefix. If an IPv6 address without mode is specified, then
2518 <literal>static
</literal> mode is assumed.
2523 <term><option>prefixstable[:
<replaceable>ADDRESS
</replaceable>][,
<replaceable>UUID
</replaceable>]
</option></term>
2526 The algorithm specified in
2527 <ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink> will be used to
2528 generate interface identifiers. This mode can optionally take an IPv6 address
2529 separated with a colon (
<literal>:
</literal>). If an IPv6 address is specified,
2530 then an interface identifier is generated only when a prefix received in an RA
2531 message matches the supplied address.
2534 This mode can also optionally take a non-null UUID in the format which
2535 <function>sd_id128_from_string()
</function> accepts, e.g.
2536 <literal>86b123b969ba4b7eb8b3d8605123525a
</literal> or
2537 <literal>86b123b9-
69ba-
4b7e-b8b3-d8605123525a
</literal>. If a UUID is specified, the
2538 value is used as the secret key to generate interface identifiers. If not specified,
2539 then an application specific ID generated with the system's machine-ID will be used
2540 as the secret key. See
2541 <citerefentry><refentrytitle>sd-id128
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
2542 <citerefentry><refentrytitle>sd_id128_from_string
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
2544 <citerefentry><refentrytitle>sd_id128_get_machine
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
2547 Note that the
<literal>prefixstable
</literal> algorithm uses both the interface
2548 name and MAC address as input to the hash to compute the interface identifier, so
2549 if either of those are changed the resulting interface identifier (and address)
2550 will be changed, even if the prefix received in the RA message has not been
2557 <para>If no address generation mode is specified (which is the default), or a received
2558 prefix does not match any of the addresses provided in
<literal>prefixstable
</literal>
2559 mode, then the EUI-
64 algorithm will be used for Ethernet or InfiniBand interfaces,
2560 otherwise
<literal>prefixstable
</literal> will be used to form an interface identifier for
2563 <para>This setting can be specified multiple times. If an empty string is assigned, then
2564 the all previous assignments are cleared.
</para>
2567 <programlisting>Token=eui64
2569 Token=static:::
1a:
2b:
3c:
4d
2571 Token=prefixstable:
2002:da8:
1::
</programlisting></para>
2576 <term><varname>UseDNS=
</varname></term>
2578 <para>When true (the default), the DNS servers received in the Router Advertisement will be used.
</para>
2580 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
2581 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2586 <term><varname>UseDomains=
</varname></term>
2588 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
2589 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link,
2590 similarly to the effect of the
<option>Domains=
</option> setting. If set to
2591 <literal>route
</literal>, the domain name received via IPv6 RA will be used for routing DNS queries
2592 only, but not for searching, similarly to the effect of the
<option>Domains=
</option> setting when
2593 the argument is prefixed with
<literal>~
</literal>. Defaults to false.
</para>
2595 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
2596 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
2597 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
2598 single-label names.
</para>
2600 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
2601 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2606 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
2608 <para>The table identifier for the routes received in the Router Advertisement. Takes one of
2609 predefined names
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
2610 and names defined in
<varname>RouteTable=
</varname> in
2611 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2612 or a number between
1…
4294967295.
</para>
2614 <para>When used in combination with
<varname>VRF=
</varname>, the VRF's routing table is
2615 used when this parameter is not specified.
</para>
2620 <term><varname>RouteMetric=
</varname></term>
2622 <para>Set the routing metric for the routes received in the Router Advertisement. Takes an unsigned
2623 integer in the range
0…
4294967295, or three unsigned integer separated with
<literal>:
</literal>,
2624 in that case the first one is used when the router preference is high, the second is for medium
2625 preference, and the last is for low preference
2626 (
<literal><replaceable>high
</replaceable>:
<replaceable>medium
</replaceable>:
<replaceable>low
</replaceable></literal>).
2627 Defaults to
<literal>512:
1024:
2048</literal>.
</para>
2632 <term><varname>QuickAck=
</varname></term>
2634 <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
2635 the received RAs. When unset, the kernel's default will be used.
</para>
2640 <term><varname>UseMTU=
</varname></term>
2642 <para>Takes a boolean. When true, the MTU received in the Router Advertisement will be
2643 used. Defaults to true.
</para>
2648 <term><varname>UseHopLimit=
</varname></term>
2650 <para>Takes a boolean. When true, the hop limit received in the Router Advertisement will be set to routes
2651 configured based on the advertisement. See also
<varname>IPv6HopLimit=
</varname>. Defaults to true.
</para>
2656 <term><varname>UseGateway=
</varname></term>
2658 <para>When true (the default), the router address will be configured as the default gateway.
2664 <term><varname>UseRoutePrefix=
</varname></term>
2666 <para>When true (the default), the routes corresponding to the route prefixes received in
2667 the Router Advertisement will be configured.
</para>
2672 <term><varname>UseCaptivePortal=
</varname></term>
2674 <para>When true (the default), the captive portal received in the Router Advertisement will be recorded
2675 and made available to client programs and displayed in the networkctl status output per-link.
</para>
2680 <term><varname>UseAutonomousPrefix=
</varname></term>
2682 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
2683 precedence over any statically configured ones.
</para>
2688 <term><varname>UseOnLinkPrefix=
</varname></term>
2690 <para>When true (the default), the onlink prefix received in the Router Advertisement will be
2691 used and takes precedence over any statically configured ones.
</para>
2696 <term><varname>RouterDenyList=
</varname></term>
2698 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
2699 take a prefix length after
<literal>/
</literal>. Any information advertised by the listed
2700 router is ignored.
</para>
2705 <term><varname>RouterAllowList=
</varname></term>
2707 <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
2708 take a prefix length after
<literal>/
</literal>. Only information advertised by the listed
2709 router is accepted. Note that if
<varname>RouterAllowList=
</varname> is configured then
2710 <varname>RouterDenyList=
</varname> is ignored.
</para>
2715 <term><varname>PrefixDenyList=
</varname></term>
2717 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
2718 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
2719 in the list are ignored.
</para>
2724 <term><varname>PrefixAllowList=
</varname></term>
2726 <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
2727 prefix length after
<literal>/
</literal>. IPv6 prefixes supplied via router advertisements
2728 in the list are allowed. Note that if
<varname>PrefixAllowList=
</varname> is configured
2729 then
<varname>PrefixDenyList=
</varname> is ignored.
</para>
2734 <term><varname>RouteDenyList=
</varname></term>
2736 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
2737 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
2738 advertisements in the list are ignored.
</para>
2743 <term><varname>RouteAllowList=
</varname></term>
2745 <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
2746 its prefix length after
<literal>/
</literal>. IPv6 route prefixes supplied via router
2747 advertisements in the list are allowed. Note that if
<varname>RouteAllowList=
</varname> is
2748 configured then
<varname>RouteDenyList=
</varname> is ignored.
</para>
2753 <term><varname>DHCPv6Client=
</varname></term>
2755 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true, the
2756 DHCPv6 client will be started in
<literal>solicit
</literal> mode if the RA has the
2757 <literal>managed
</literal> flag or
<literal>information-request
</literal> mode if the RA
2758 lacks the
<literal>managed
</literal> flag but has the
2759 <literal>other configuration
</literal> flag. If set to
<literal>always
</literal>, the
2760 DHCPv6 client will be started in
<literal>solicit
</literal> mode when an RA is received,
2761 even if neither the
<literal>managed
</literal> nor the
2762 <literal>other configuration
</literal> flag is set in the RA. This will be ignored when
2763 <varname>WithoutRA=
</varname> in the [DHCPv6] section is enabled, or
2764 <varname>UplinkInterface=:self
</varname> in the [DHCPPrefixDelegation] section is
2765 specified. Defaults to true.
</para>
2770 <term><varname>NetLabel=
</varname></term>
2772 <para>This applies the NetLabel for the addresses received with RA, like
2773 <varname>NetLabel=
</varname> in [Address] section applies it to statically configured
2774 addresses. See
<varname>NetLabel=
</varname> in [Address] section for more details.
</para>
2781 <title>[DHCPServer] Section Options
</title>
2782 <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
2783 <varname>DHCPServer=
</varname> option described above:
</para>
2785 <variablelist class='network-directives'
>
2788 <term><varname>ServerAddress=
</varname></term>
2789 <listitem><para>Specifies server address for the DHCP server. Takes an IPv4 address with prefix
2790 length, for example
192.168.0.1/
24. This setting may be useful when the link on
2791 which the DHCP server is running has multiple static addresses. When unset, one of static addresses
2792 in the link will be automatically selected. Defaults to unset.
</para></listitem>
2796 <term><varname>PoolOffset=
</varname></term>
2797 <term><varname>PoolSize=
</varname></term>
2799 <listitem><para>Configures the pool of addresses to hand out. The pool
2800 is a contiguous sequence of IP addresses in the subnet configured for
2801 the server address, which does not include the subnet nor the broadcast
2802 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
2803 from the start of subnet, or zero to use the default value.
2804 <varname>PoolSize=
</varname> takes the number of IP addresses in the
2805 pool or zero to use the default value. By default, the pool starts at
2806 the first address after the subnet address and takes up the rest of
2807 the subnet, excluding the broadcast address. If the pool includes
2808 the server address (the default), this is reserved and not handed
2809 out to clients.
</para></listitem>
2813 <term><varname>DefaultLeaseTimeSec=
</varname></term>
2814 <term><varname>MaxLeaseTimeSec=
</varname></term>
2816 <listitem><para>Control the default and maximum DHCP lease
2817 time to pass to clients. These settings take time values in seconds or
2818 another common time unit, depending on the suffix. The default
2819 lease time is used for clients that did not ask for a specific
2820 lease time. If a client asks for a lease time longer than the
2821 maximum lease time, it is automatically shortened to the
2822 specified time. The default lease time defaults to
1h, the
2823 maximum lease time to
12h. Shorter lease times are beneficial
2824 if the configuration data in DHCP leases changes frequently
2825 and clients shall learn the new settings with shorter
2826 latencies. Longer lease times reduce the generated DHCP
2827 network traffic.
</para></listitem>
2831 <term><varname>UplinkInterface=
</varname></term>
2832 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
2833 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS, NTP, or SIP
2834 servers is enabled but no servers are specified, the servers configured in the uplink interface
2835 will be emitted. When
<literal>:auto
</literal>, the link which has a default gateway with the
2836 highest priority will be automatically selected. When
<literal>:none
</literal>, no uplink
2837 interface will be selected. Defaults to
<literal>:auto
</literal>.
</para></listitem>
2841 <term><varname>EmitDNS=
</varname></term>
2842 <term><varname>DNS=
</varname></term>
2844 <listitem><para><varname>EmitDNS=
</varname> takes a boolean. Configures whether the DHCP leases
2845 handed out to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
2846 The DNS servers to pass to clients may be configured with the
<varname>DNS=
</varname> option,
2847 which takes a list of IPv4 addresses, or special value
<literal>_server_address
</literal> which
2848 will be converted to the address used by the DHCP server.
</para>
2850 <para>If the
<varname>EmitDNS=
</varname> option is enabled but no servers configured, the
2851 servers are automatically propagated from an
"uplink" interface that has appropriate servers
2852 set. The
"uplink" interface is determined by the default route of the system with the highest
2853 priority. Note that this information is acquired at the time the lease is handed out, and does
2854 not take uplink interfaces into account that acquire DNS server information at a later point.
2855 If no suitable uplink interface is found the DNS server data from
2856 <filename>/etc/resolv.conf
</filename> is used. Also, note that the leases are not refreshed if
2857 the uplink network configuration changes. To ensure clients regularly acquire the most current
2858 uplink DNS server information, it is thus advisable to shorten the DHCP lease time via
2859 <varname>MaxLeaseTimeSec=
</varname> described above.
</para>
2861 <para>This setting can be specified multiple times. If an empty string is specified, then all
2862 DNS servers specified earlier are cleared.
</para></listitem>
2866 <term><varname>EmitNTP=
</varname></term>
2867 <term><varname>NTP=
</varname></term>
2868 <term><varname>EmitSIP=
</varname></term>
2869 <term><varname>SIP=
</varname></term>
2870 <term><varname>EmitPOP3=
</varname></term>
2871 <term><varname>POP3=
</varname></term>
2872 <term><varname>EmitSMTP=
</varname></term>
2873 <term><varname>SMTP=
</varname></term>
2874 <term><varname>EmitLPR=
</varname></term>
2875 <term><varname>LPR=
</varname></term>
2877 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname> settings
2878 described above, these settings configure whether and what server information for the indicate
2879 protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
2880 defaults apply as for
<varname>EmitDNS=
</varname> and
<varname>DNS=
</varname>.
</para></listitem>
2884 <term><varname>EmitRouter=
</varname></term>
2885 <term><varname>Router=
</varname></term>
2887 <listitem><para>The
<varname>EmitRouter=
</varname> setting takes a boolean value, and configures
2888 whether the DHCP lease should contain the router option. The
<varname>Router=
</varname> setting
2889 takes an IPv4 address, and configures the router address to be emitted. When the
2890 <varname>Router=
</varname> setting is not specified, then the server address will be used for
2891 the router option. When the
<varname>EmitRouter=
</varname> setting is disabled, the
2892 <varname>Router=
</varname> setting will be ignored. The
<varname>EmitRouter=
</varname> setting
2893 defaults to true, and the
<varname>Router=
</varname> setting defaults to unset.
2898 <term><varname>EmitTimezone=
</varname></term>
2899 <term><varname>Timezone=
</varname></term>
2901 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
2902 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
2903 <varname>Timezone=
</varname> setting takes a timezone string
2904 (such as
<literal>Europe/Berlin
</literal> or
2905 <literal>UTC
</literal>) to pass to clients. If no explicit
2906 timezone is set, the system timezone of the local host is
2907 propagated, as determined by the
2908 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
2912 <term><varname>BootServerAddress=
</varname></term>
2915 <para>Takes an IPv4 address of the boot server used by e.g. PXE boot systems. When specified, this
2916 address is sent in the
<option>siaddr
</option> field of the DHCP message header. See
<ulink
2917 url=
"https://www.rfc-editor.org/rfc/rfc2131.html">RFC
2131</ulink> for more details. Defaults to
2923 <term><varname>BootServerName=
</varname></term>
2926 <para>Takes a name of the boot server used by e.g. PXE boot systems. When specified, this name is
2927 sent in the DHCP option
66 (
"TFTP server name"). See
<ulink
2928 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
2931 <para>Note that typically setting one of
<varname>BootServerName=
</varname> or
2932 <varname>BootServerAddress=
</varname> is sufficient, but both can be set too, if desired.
</para>
2937 <term><varname>BootFilename=
</varname></term>
2940 <para>Takes a path or URL to a file loaded by e.g. a PXE boot loader. When specified, this path is
2941 sent in the DHCP option
67 (
"Bootfile name"). See
<ulink
2942 url=
"https://www.rfc-editor.org/rfc/rfc2132.html">RFC
2132</ulink> for more details. Defaults to
2948 <term><varname>SendOption=
</varname></term>
2950 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
2951 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2952 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
2953 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
2954 <literal>string
</literal>. Special characters in the data string may be escaped using
2955 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2956 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2957 then all options specified earlier are cleared. Defaults to unset.
</para>
2962 <term><varname>SendVendorOption=
</varname></term>
2964 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
2965 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2966 The option number is an integer in the range
1…
254. The type takes one of
<literal>uint8
</literal>,
2967 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
2968 <literal>string
</literal>. Special characters in the data string may be escaped using
2969 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2970 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2971 then all options specified earlier are cleared. Defaults to unset.
</para>
2975 <term><varname>BindToInterface=
</varname></term>
2977 <para>Takes a boolean value. When
<literal>yes
</literal>, DHCP server socket will be bound
2978 to its network interface and all socket communication will be restricted to this interface.
2979 Defaults to
<literal>yes
</literal>, except if
<varname>RelayTarget=
</varname> is used (see below),
2980 in which case it defaults to
<literal>no
</literal>.
</para>
2984 <term><varname>RelayTarget=
</varname></term>
2986 <para>Takes an IPv4 address, which must be in the format described in
2987 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
2988 Turns this DHCP server into a DHCP relay agent. See
<ulink url=
"https://tools.ietf.org/html/rfc1542">RFC
1542</ulink>.
2989 The address is the address of DHCP server or another relay agent to forward DHCP messages to and from.
</para>
2993 <term><varname>RelayAgentCircuitId=
</varname></term>
2995 <para>Specifies value for Agent Circuit ID suboption of Relay Agent Information option.
2996 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
2997 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
2998 Defaults to unset (means no Agent Circuit ID suboption is generated).
2999 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3003 <term><varname>RelayAgentRemoteId=
</varname></term>
3005 <para>Specifies value for Agent Remote ID suboption of Relay Agent Information option.
3006 Takes a string, which must be in the format
<literal>string:
<replaceable>value
</replaceable></literal>,
3007 where
<literal><replaceable>value
</replaceable></literal> should be replaced with the value of the suboption.
3008 Defaults to unset (means no Agent Remote ID suboption is generated).
3009 Ignored if
<varname>RelayTarget=
</varname> is not specified.
</para>
3017 <title>[DHCPServerStaticLease] Section Options
</title>
3018 <para>The
<literal>[DHCPServerStaticLease]
</literal> section configures a static DHCP lease to assign a
3019 fixed IPv4 address to a specific device based on its MAC address. This section can be specified multiple
3022 <variablelist class='network-directives'
>
3024 <term><varname>MACAddress=
</varname></term>
3026 <listitem><para>The hardware address of a device to match. This key is mandatory.
</para></listitem>
3030 <term><varname>Address=
</varname></term>
3032 <listitem><para>The IPv4 address that should be assigned to the device that was matched with
3033 <varname>MACAddress=
</varname>. This key is mandatory.
</para></listitem>
3039 <title>[IPv6SendRA] Section Options
</title>
3040 <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
3041 to act as a router, if enabled via the
<varname>IPv6SendRA=
</varname> option described above. IPv6
3042 network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
3045 <variablelist class='network-directives'
>
3048 <term><varname>Managed=
</varname></term>
3049 <term><varname>OtherInformation=
</varname></term>
3051 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
3052 addresses on the network link when
<varname>Managed=
</varname>
3053 is set to
<literal>true
</literal> or if only additional network
3054 information can be obtained via DHCPv6 for the network link when
3055 <varname>OtherInformation=
</varname> is set to
3056 <literal>true
</literal>. Both settings default to
3057 <literal>false
</literal>, which means that a DHCPv6 server is not being
3058 used.
</para></listitem>
3062 <term><varname>RouterLifetimeSec=
</varname></term>
3064 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. The value must be
0
3065 seconds, or between
4 seconds and
9000 seconds. When set to
0, the host is not acting as a router.
3066 Defaults to
1800 seconds (
30 minutes).
</para>
3071 <term><varname>RouterPreference=
</varname></term>
3073 <listitem><para>Configures IPv6 router preference if
3074 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
3075 <literal>high
</literal>,
<literal>medium
</literal> and
3076 <literal>low
</literal>, with
<literal>normal
</literal> and
3077 <literal>default
</literal> added as synonyms for
3078 <literal>medium
</literal> just to make configuration easier. See
3079 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
3080 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
3084 <term><varname>UplinkInterface=
</varname></term>
3085 <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
3086 values
<literal>:none
</literal> and
<literal>:auto
</literal>. When emitting DNS servers or
3087 search domains is enabled but no servers are specified, the servers configured in the uplink
3088 interface will be emitted. When
<literal>:auto
</literal>, the value specified to the same
3089 setting in the [DHCPPrefixDelegation] section will be used if
3090 <varname>DHCPPrefixDelegation=
</varname> is enabled, otherwise the link which has a default
3091 gateway with the highest priority will be automatically selected. When
<literal>:none
</literal>,
3092 no uplink interface will be selected. Defaults to
<literal>:auto
</literal>.
</para></listitem>
3096 <term><varname>EmitDNS=
</varname></term>
3097 <term><varname>DNS=
</varname></term>
3099 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
3100 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is true.
3101 <varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that case
3102 the IPv6 link-local address is distributed. If
<varname>DNS=
</varname> is empty, DNS servers are
3103 read from the [Network] section. If the [Network] section does not contain any DNS servers
3104 either, DNS servers from the uplink interface specified in
<varname>UplinkInterface=
</varname>
3105 will be used. When
<varname>EmitDNS=
</varname> is false, no DNS server information is sent in
3106 Router Advertisement messages.
<varname>EmitDNS=
</varname> defaults to true.
</para></listitem>
3110 <term><varname>EmitDomains=
</varname></term>
3111 <term><varname>Domains=
</varname></term>
3113 <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
3114 <varname>EmitDomains=
</varname> is true. If
<varname>Domains=
</varname> is empty, DNS search
3115 domains are read from the [Network] section. If the [Network] section does not contain any DNS
3116 search domains either, DNS search domains from the uplink interface specified in
3117 <varname>UplinkInterface=
</varname> will be used. When
<varname>EmitDomains=
</varname> is false,
3118 no DNS search domain information is sent in Router Advertisement messages.
3119 <varname>EmitDomains=
</varname> defaults to true.
</para></listitem>
3123 <term><varname>DNSLifetimeSec=
</varname></term>
3125 <listitem><para>Lifetime in seconds for the DNS server addresses listed in
3126 <varname>DNS=
</varname> and search domains listed in
<varname>Domains=
</varname>. Defaults to
3127 3600 seconds (one hour).
</para></listitem>
3134 <title>[IPv6Prefix] Section Options
</title>
3135 <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
3136 Advertisements. See
<ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink> for further
3139 <variablelist class='network-directives'
>
3142 <term><varname>AddressAutoconfiguration=
</varname></term>
3143 <term><varname>OnLink=
</varname></term>
3145 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
3146 autoconfigured with this prefix and whether the prefix can be used for
3147 onlink determination. Both settings default to
<literal>true
</literal>
3148 in order to ease configuration.
3153 <term><varname>Prefix=
</varname></term>
3155 <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
3156 IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
3157 <literal>/
</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
3158 prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
3159 prefix to another.
</para></listitem>
3163 <term><varname>PreferredLifetimeSec=
</varname></term>
3164 <term><varname>ValidLifetimeSec=
</varname></term>
3166 <listitem><para>Preferred and valid lifetimes for the prefix measured in seconds.
3167 <varname>PreferredLifetimeSec=
</varname> defaults to
1800 seconds (
30 minutes) and
3168 <varname>ValidLifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para></listitem>
3172 <term><varname>Assign=
</varname></term>
3173 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
3178 <term><varname>Token=
</varname></term>
3180 <para>Specifies an optional address generation mode for assigning an address in each
3181 prefix. This accepts the same syntax as
<varname>Token=
</varname> in the [IPv6AcceptRA]
3182 section. If
<varname>Assign=
</varname> is set to false, then this setting will be ignored.
3183 Defaults to unset, which means the EUI-
64 algorithm will be used.
</para>
3188 <term><varname>RouteMetric=
</varname></term>
3190 <para>The metric of the prefix route. Takes an unsigned integer in the range
0…
4294967295.
3191 When unset or set to
0, the kernel's default value is used. This setting is ignored when
3192 <varname>Assign=
</varname> is false.
</para>
3199 <title>[IPv6RoutePrefix] Section Options
</title>
3200 <para>One or more [IPv6RoutePrefix] sections contain the IPv6
3201 prefix routes that are announced via Router Advertisements. See
3202 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
3203 for further details.
</para>
3205 <variablelist class='network-directives'
>
3208 <term><varname>Route=
</varname></term>
3210 <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
3211 IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
3212 separated by a
<literal>/
</literal> character. Use multiple [IPv6RoutePrefix] sections to configure
3213 multiple IPv6 prefix routes.
</para></listitem>
3217 <term><varname>LifetimeSec=
</varname></term>
3219 <listitem><para>Lifetime for the route prefix measured in seconds.
3220 <varname>LifetimeSec=
</varname> defaults to
3600 seconds (one hour).
</para></listitem>
3227 <title>[Bridge] Section Options
</title>
3228 <para>The [Bridge] section accepts the following keys:
</para>
3229 <variablelist class='network-directives'
>
3231 <term><varname>UnicastFlood=
</varname></term>
3233 <para>Takes a boolean. Controls whether the bridge should flood
3234 traffic for which an FDB entry is missing and the destination
3235 is unknown through this port. When unset, the kernel's default will be used.
3240 <term><varname>MulticastFlood=
</varname></term>
3242 <para>Takes a boolean. Controls whether the bridge should flood
3243 traffic for which an MDB entry is missing and the destination
3244 is unknown through this port. When unset, the kernel's default will be used.
3249 <term><varname>MulticastToUnicast=
</varname></term>
3251 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
3252 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
3253 When unset, the kernel's default will be used.
3258 <term><varname>NeighborSuppression=
</varname></term>
3260 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
3261 this port. When unset, the kernel's default will be used.
3266 <term><varname>Learning=
</varname></term>
3268 <para>Takes a boolean. Configures whether MAC address learning is enabled for
3269 this port. When unset, the kernel's default will be used.
3274 <term><varname>HairPin=
</varname></term>
3276 <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
3277 was received. When this flag is false, then the bridge will not forward traffic back out of the
3278 receiving port. When unset, the kernel's default will be used.
</para>
3282 <term><varname>Isolated=
</varname></term>
3284 <para>Takes a boolean. Configures whether this port is isolated or not. Within a bridge,
3285 isolated ports can only communicate with non-isolated ports. When set to true, this port can only
3286 communicate with other ports whose Isolated setting is false. When set to false, this port
3287 can communicate with any other ports. When unset, the kernel's default will be used.
</para>
3291 <term><varname>UseBPDU=
</varname></term>
3293 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
3294 processed by the bridge port. When unset, the kernel's default will be used.
</para>
3298 <term><varname>FastLeave=
</varname></term>
3300 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
3301 traffic on a port that receives an IGMP Leave message. It is only used with
3302 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
3306 <term><varname>AllowPortToBeRoot=
</varname></term>
3308 <para>Takes a boolean. Configures whether a given port is allowed to
3309 become a root port. Only used when STP is enabled on the bridge.
3310 When unset, the kernel's default will be used.
</para>
3314 <term><varname>ProxyARP=
</varname></term>
3316 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
3317 When unset, the kernel's default will be used.
</para>
3321 <term><varname>ProxyARPWiFi=
</varname></term>
3323 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
3324 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
3325 When unset, the kernel's default will be used.
</para>
3329 <term><varname>MulticastRouter=
</varname></term>
3331 <para>Configures this port for having multicast routers attached. A port with a multicast
3332 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
3333 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
3334 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
3335 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
3336 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
3340 <term><varname>Cost=
</varname></term>
3342 <para>Sets the
"cost" of sending packets of this interface.
3343 Each port in a bridge may have a different speed and the cost
3344 is used to decide which link to use. Faster interfaces
3345 should have lower costs. It is an integer value between
1 and
3350 <term><varname>Priority=
</varname></term>
3352 <para>Sets the
"priority" of sending packets on this interface.
3353 Each port in a bridge may have a different priority which is used
3354 to decide which link to use. Lower value means higher priority.
3355 It is an integer value between
0 to
63. Networkd does not set any
3356 default, meaning the kernel default value of
32 is used.
</para>
3362 <title>[BridgeFDB] Section Options
</title>
3363 <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
3364 keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.
</para>
3366 <variablelist class='network-directives'
>
3368 <term><varname>MACAddress=
</varname></term>
3370 <para>As in the [Network] section. This key is mandatory.
</para>
3374 <term><varname>Destination=
</varname></term>
3376 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
3380 <term><varname>VLANId=
</varname></term>
3382 <para>The VLAN ID for the new static MAC table entry. If
3383 omitted, no VLAN ID information is appended to the new static MAC
3388 <term><varname>VNI=
</varname></term>
3390 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
3391 the remote VXLAN tunnel endpoint. Takes a number in the range
1…
16777215.
3392 Defaults to unset.
</para>
3396 <term><varname>AssociatedWith=
</varname></term>
3398 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
3399 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
3400 <literal>use
</literal> means the address is in use. User space can use this option to
3401 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
3402 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
3403 means the address is associated with master devices fdb.
<literal>router
</literal> means
3404 the destination address is associated with a router. Note that it's valid if the referenced
3405 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
3409 <term><varname>OutgoingInterface=
</varname></term>
3411 <para>Specifies the name or index of the outgoing interface for the VXLAN device driver to
3412 reach the remote VXLAN tunnel endpoint. Defaults to unset.
</para>
3418 <title>[BridgeMDB] Section Options
</title>
3419 <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
3420 keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.
</para>
3422 <variablelist class='network-directives'
>
3424 <term><varname>MulticastGroupAddress=
</varname></term>
3426 <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.
</para>
3430 <term><varname>VLANId=
</varname></term>
3432 <para>The VLAN ID for the new entry. Valid ranges are
0 (no VLAN) to
4094. Optional, defaults to
0.
</para>
3439 <title>[LLDP] Section Options
</title>
3440 <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
3442 <variablelist class='network-directives'
>
3444 <term><varname>MUDURL=
</varname></term>
3446 <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
3447 LLDP packets. The syntax and semantics are the same as for
<varname>MUDURL=
</varname> in the
3448 [DHCPv4] section described above.
</para>
3450 <para>The MUD URLs received via LLDP packets are saved and can be read using the
3451 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
3458 <title>[CAN] Section Options
</title>
3459 <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
3460 following keys:
</para>
3461 <variablelist class='network-directives'
>
3463 <term><varname>BitRate=
</varname></term>
3465 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
3466 be used here. Takes a number in the range
1…
4294967295.
</para>
3470 <term><varname>SamplePoint=
</varname></term>
3472 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
3473 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>). This will be ignored when
3474 <varname>BitRate=
</varname> is unspecified.
</para>
3478 <term><varname>TimeQuantaNSec=
</varname></term>
3479 <term><varname>PropagationSegment=
</varname></term>
3480 <term><varname>PhaseBufferSegment1=
</varname></term>
3481 <term><varname>PhaseBufferSegment2=
</varname></term>
3482 <term><varname>SyncJumpWidth=
</varname></term>
3484 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
3485 synchronization jump width, which allow one to define the CAN bit-timing in a hardware
3486 independent format as proposed by the Bosch CAN
2.0 Specification.
3487 <varname>TimeQuantaNSec=
</varname> takes a timespan in nanoseconds.
3488 <varname>PropagationSegment=
</varname>,
<varname>PhaseBufferSegment1=
</varname>,
3489 <varname>PhaseBufferSegment2=
</varname>, and
<varname>SyncJumpWidth=
</varname> take number
3490 of time quantum specified in
<varname>TimeQuantaNSec=
</varname> and must be an unsigned
3491 integer in the range
0…
4294967295. These settings except for
3492 <varname>SyncJumpWidth=
</varname> will be ignored when
<varname>BitRate=
</varname> is
3497 <term><varname>DataBitRate=
</varname></term>
3498 <term><varname>DataSamplePoint=
</varname></term>
3500 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
3501 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
3505 <term><varname>DataTimeQuantaNSec=
</varname></term>
3506 <term><varname>DataPropagationSegment=
</varname></term>
3507 <term><varname>DataPhaseBufferSegment1=
</varname></term>
3508 <term><varname>DataPhaseBufferSegment2=
</varname></term>
3509 <term><varname>DataSyncJumpWidth=
</varname></term>
3511 <para>Specifies the time quanta, propagation segment, phase buffer segment
1 and
2, and the
3512 synchronization jump width for the data phase, if CAN-FD is used. These settings are
3513 analogous to the
<varname>TimeQuantaNSec=
</varname> or related settings.
</para>
3517 <term><varname>FDMode=
</varname></term>
3519 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
3520 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
3521 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys, or
3522 <varname>DataTimeQuanta=
</varname> and related settings.
</para>
3526 <term><varname>FDNonISO=
</varname></term>
3528 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
3529 interface. When unset, the kernel's default will be used.
</para>
3533 <term><varname>RestartSec=
</varname></term>
3535 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
3536 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
3537 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
3538 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
3539 automatic restart off. By default automatic restart is disabled.
</para>
3543 <term><varname>Termination=
</varname></term>
3545 <para>Takes a boolean or a termination resistor value in ohm in the range
0…
65535. When
3546 <literal>yes
</literal>, the termination resistor is set to
120 ohm. When
3547 <literal>no
</literal> or
<literal>0</literal> is set, the termination resistor is disabled.
3548 When unset, the kernel's default will be used.
</para>
3552 <term><varname>TripleSampling=
</varname></term>
3554 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
3555 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
3559 <term><varname>BusErrorReporting=
</varname></term>
3561 <para>Takes a boolean. When
<literal>yes
</literal>, reporting of CAN bus errors is activated
3562 (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
3563 unable to send recessive bit, bus overload, active error announcement, error occurred on
3564 transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
3565 single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.
</para>
3569 <term><varname>ListenOnly=
</varname></term>
3571 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
3572 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
3573 bit. Listen-only mode is important to debug CAN networks without interfering with the
3574 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
3579 <term><varname>Loopback=
</varname></term>
3581 <para>Takes a boolean. When
<literal>yes
</literal>, loopback mode is enabled. When the
3582 loopback mode is enabled, the interface treats messages transmitted by itself as received
3583 messages. The loopback mode is important to debug CAN networks. When unset, the kernel's
3584 default will be used.
</para>
3588 <term><varname>OneShot=
</varname></term>
3590 <para>Takes a boolean. When
<literal>yes
</literal>, one-shot mode is enabled. When unset,
3591 the kernel's default will be used.
</para>
3595 <term><varname>PresumeAck=
</varname></term>
3597 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will ignore missing CAN
3598 ACKs. When unset, the kernel's default will be used.
</para>
3602 <term><varname>ClassicDataLengthCode=
</varname></term>
3604 <para>Takes a boolean. When
<literal>yes
</literal>, the interface will handle the
4bit data
3605 length code (DLC). When unset, the kernel's default will be used.
</para>
3612 <title>[IPoIB] Section Options
</title>
3613 <para>The [IPoIB] section manages the IP over Infiniband and accepts the following keys:
</para>
3614 <variablelist class='network-directives'
>
3615 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_mode" />
3616 <xi:include href=
"systemd.netdev.xml" xpointer=
"ipoib_umcast" />
3621 <title>[QDisc] Section Options
</title>
3622 <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).
</para>
3624 <variablelist class='network-directives'
>
3626 <term><varname>Parent=
</varname></term>
3628 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
3629 or
<literal>ingress
</literal>. This is mandatory.
</para>
3633 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3638 <title>[NetworkEmulator] Section Options
</title>
3639 <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
3640 can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
3641 applications, or limit the bandwidth usage of a particular service to simulate internet connections.
3644 <variablelist class='network-directives'
>
3645 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3646 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3649 <term><varname>DelaySec=
</varname></term>
3651 <para>Specifies the fixed amount of delay to be added to all packets going out of the
3652 interface. Defaults to unset.
</para>
3657 <term><varname>DelayJitterSec=
</varname></term>
3659 <para>Specifies the chosen delay to be added to the packets outgoing to the network
3660 interface. Defaults to unset.
</para>
3665 <term><varname>PacketLimit=
</varname></term>
3667 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
3668 An unsigned integer in the range
0…
4294967294. Defaults to
1000.
</para>
3673 <term><varname>LossRate=
</varname></term>
3675 <para>Specifies an independent loss probability to be added to the packets outgoing from the
3676 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
3681 <term><varname>DuplicateRate=
</varname></term>
3683 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
3684 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
3691 <title>[TokenBucketFilter] Section Options
</title>
3692 <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
3695 <variablelist class='network-directives'
>
3696 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3697 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3700 <term><varname>LatencySec=
</varname></term>
3702 <para>Specifies the latency parameter, which specifies the maximum amount of time a
3703 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
3708 <term><varname>LimitBytes=
</varname></term>
3710 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
3711 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
3712 respectively, to the base of
1024. Defaults to unset.
</para>
3717 <term><varname>BurstBytes=
</varname></term>
3719 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
3720 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
3721 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to
3727 <term><varname>Rate=
</varname></term>
3729 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
3730 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
3731 Defaults to unset.
</para>
3736 <term><varname>MPUBytes=
</varname></term>
3738 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
3739 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3740 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to zero.
</para>
3745 <term><varname>PeakRate=
</varname></term>
3747 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
3748 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
3749 1000. Defaults to unset.
</para>
3754 <term><varname>MTUBytes=
</varname></term>
3756 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
3757 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
3758 Defaults to unset.
</para>
3765 <title>[PIE] Section Options
</title>
3766 <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
3767 controller-Enhanced (PIE).
</para>
3769 <variablelist class='network-directives'
>
3770 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3771 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3774 <term><varname>PacketLimit=
</varname></term>
3776 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3777 incoming packets are dropped. An unsigned integer in the range
1…
4294967294. Defaults to unset and
3778 kernel's default is used.
</para>
3785 <title>[FlowQueuePIE] Section Options
</title>
3786 <para>The
<literal>[FlowQueuePIE]
</literal> section manages the queueing discipline
3787 (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).
</para>
3789 <variablelist class='network-directives'
>
3790 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3791 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3794 <term><varname>PacketLimit=
</varname></term>
3796 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3797 incoming packets are dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and
3798 kernel's default is used.
</para>
3805 <title>[StochasticFairBlue] Section Options
</title>
3806 <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
3809 <variablelist class='network-directives'
>
3810 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3811 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3814 <term><varname>PacketLimit=
</varname></term>
3816 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
3817 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
3818 kernel's default is used.
</para>
3825 <title>[StochasticFairnessQueueing] Section Options
</title>
3826 <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
3827 fairness queueing (sfq).
</para>
3829 <variablelist class='network-directives'
>
3830 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3831 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3834 <term><varname>PerturbPeriodSec=
</varname></term>
3836 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
3843 <title>[BFIFO] Section Options
</title>
3844 <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
3847 <variablelist class='network-directives'
>
3848 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3849 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3852 <term><varname>LimitBytes=
</varname></term>
3854 <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
3855 in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
3856 reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
3857 as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
3858 kernel default is used.
</para>
3865 <title>[PFIFO] Section Options
</title>
3866 <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
3869 <variablelist class='network-directives'
>
3870 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3871 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3874 <term><varname>PacketLimit=
</varname></term>
3876 <para>Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents
3877 overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this
3878 limit is reached, incoming packets are dropped. An unsigned integer in the range
3879 0…
4294967294. Defaults to unset and kernel's default is used.
</para>
3886 <title>[PFIFOHeadDrop] Section Options
</title>
3887 <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
3888 Head Drop (pfifo_head_drop).
</para>
3890 <variablelist class='network-directives'
>
3891 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3892 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3895 <term><varname>PacketLimit=
</varname></term>
3897 <para>As in [PFIFO] section.
</para></listitem>
3903 <title>[PFIFOFast] Section Options
</title>
3904 <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
3905 (pfifo_fast).
</para>
3907 <variablelist class='network-directives'
>
3908 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3909 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3914 <title>[CAKE] Section Options
</title>
3915 <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
3918 <variablelist class='network-directives'
>
3919 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3920 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3923 <term><varname>Bandwidth=
</varname></term>
3925 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
3926 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
3927 unset and kernel's default is used.
</para>
3932 <term><varname>AutoRateIngress=
</varname></term>
3934 <para>Takes a boolean value. Enables automatic capacity estimation based on traffic arriving
3935 at this qdisc. This is most likely to be useful with cellular links, which tend to change
3936 quality randomly. If this setting is enabled, the
<varname>Bandwidth=
</varname> setting is
3937 used as an initial estimate. Defaults to unset, and the kernel's default is used.
</para>
3942 <term><varname>OverheadBytes=
</varname></term>
3944 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative.
3945 Takes an integer in the range -
64…
256. Defaults to unset and kernel's default is used.
3951 <term><varname>MPUBytes=
</varname></term>
3953 <para>Rounds each packet (including overhead) up to the specified bytes. Takes an integer in
3954 the range
1…
256. Defaults to unset and kernel's default is used.
</para>
3959 <term><varname>CompensationMode=
</varname></term>
3961 <para>Takes one of
<literal>none
</literal>,
<literal>atm
</literal>, or
<literal>ptm
</literal>.
3962 Specifies the compensation mode for overhead calculation. When
<literal>none
</literal>, no
3963 compensation is taken into account. When
<literal>atm
</literal>, enables the compensation for
3964 ATM cell framing, which is normally found on ADSL links. When
<literal>ptm
</literal>, enables
3965 the compensation for PTM encoding, which is normally found on VDSL2 links and uses a
64b/
65b
3966 encoding scheme. Defaults to unset and the kernel's default is used.
</para>
3971 <term><varname>UseRawPacketSize=
</varname></term>
3973 <para>Takes a boolean value. When true, the packet size reported by the Linux kernel will be
3974 used, instead of the underlying IP packet size. Defaults to unset, and the kernel's default
3980 <term><varname>FlowIsolationMode=
</varname></term>
3982 <para>CAKE places packets from different flows into different queues, then packets from each
3983 queue are delivered fairly. This specifies whether the fairness is based on source address,
3984 destination address, individual flows, or any combination of those. The available values are:
3989 <term><option>none
</option></term>
3991 The flow isolation is disabled, and all traffic passes through a single queue.
3995 <term><option>src-host
</option></term>
3997 Flows are defined only by source address. Equivalent to the
<literal>srchost
</literal>
3998 option for
<command>tc qdisc
</command> command. See also
3999 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4003 <term><option>dst-host
</option></term>
4005 Flows are defined only by destination address. Equivalent to the
4006 <literal>dsthost
</literal> option for
<command>tc qdisc
</command> command. See also
4007 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4011 <term><option>hosts
</option></term>
4013 Flows are defined by source-destination host pairs. Equivalent to the same option for
4014 <command>tc qdisc
</command> command. See also
4015 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4019 <term><option>flows
</option></term>
4021 Flows are defined by the entire
5-tuple of source address, destination address,
4022 transport protocol, source port and destination port. Equivalent to the same option for
4023 <command>tc qdisc
</command> command. See also
4024 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4028 <term><option>dual-src-host
</option></term>
4030 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
4031 fairness is applied first over source addresses, then over individual flows. Equivalent
4032 to the
<literal>dual-srchost
</literal> option for
<command>tc qdisc
</command> command.
4034 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4038 <term><option>dual-dst-host
</option></term>
4040 Flows are defined by the
5-tuple (see
<literal>flows
</literal> in the above), and
4041 fairness is applied first over destination addresses, then over individual flows.
4042 Equivalent to the
<literal>dual-dsthost
</literal> option for
4043 <command>tc qdisc
</command> command. See also
4044 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4048 <term><option>triple
</option></term>
4050 Flows are defined by the
5-tuple (see
<literal>flows
</literal>), and fairness is
4051 applied over source and destination addresses, and also over individual flows.
4052 Equivalent to the
<literal>triple-isolate
</literal> option for
4053 <command>tc qdisc
</command> command. See also
4054 <citerefentry project='man-pages'
><refentrytitle>tc-cake
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
4059 <para>Defaults to unset and the kernel's default is used.
</para>
4064 <term><varname>NAT=
</varname></term>
4066 <para>Takes a boolean value. When true, CAKE performs a NAT lookup before applying
4067 flow-isolation rules, to determine the true addresses and port numbers of the packet, to
4068 improve fairness between hosts inside the NAT. This has no practical effect when
4069 <varname>FlowIsolationMode=
</varname> is
<literal>none
</literal> or
<literal>flows
</literal>,
4070 or if NAT is performed on a different host. Defaults to unset, and the kernel's default is
4076 <term><varname>PriorityQueueingPreset=
</varname></term>
4078 <para>CAKE divides traffic into
<literal>tins
</literal>, and each tin has its own independent
4079 set of flow-isolation queues, bandwidth threshold, and priority. This specifies the preset of
4080 tin profiles. The available values are:
</para>
4084 <term><option>besteffort
</option></term>
4086 Disables priority queueing by placing all traffic in one tin.
4090 <term><option>precedence
</option></term>
4092 Enables priority queueing based on the legacy interpretation of TOS
4093 <literal>Precedence
</literal> field. Use of this preset on the modern Internet is
4098 <term><option>diffserv8
</option></term>
4100 Enables priority queueing based on the Differentiated Service
4101 (
<literal>DiffServ
</literal>) field with eight tins: Background Traffic, High
4102 Throughput, Best Effort, Video Streaming, Low Latency Transactions, Interactive Shell,
4103 Minimum Latency, and Network Control.
4107 <term><option>diffserv4
</option></term>
4109 Enables priority queueing based on the Differentiated Service
4110 (
<literal>DiffServ
</literal>) field with four tins: Background Traffic, Best Effort,
4111 Streaming Media, and Latency Sensitive.
4115 <term><option>diffserv3
</option></term>
4117 Enables priority queueing based on the Differentiated Service
4118 (
<literal>DiffServ
</literal>) field with three tins: Background Traffic, Best Effort,
4119 and Latency Sensitive.
4124 <para>Defaults to unset, and the kernel's default is used.
</para>
4129 <term><varname>FirewallMark=
</varname></term>
4131 <para>Takes an integer in the range
1…
4294967295. When specified, firewall-mark-based
4132 overriding of CAKE's tin selection is enabled. Defaults to unset, and the kernel's default is
4138 <term><varname>Wash=
</varname></term>
4140 <para>Takes a boolean value. When true, CAKE clears the DSCP fields, except for ECN bits, of
4141 any packet passing through CAKE. Defaults to unset, and the kernel's default is used.
</para>
4146 <term><varname>SplitGSO=
</varname></term>
4148 <para>Takes a boolean value. When true, CAKE will split General Segmentation Offload (GSO)
4149 super-packets into their on-the-wire components and dequeue them individually. Defaults to
4150 unset, and the kernel's default is used.
</para>
4155 <term><varname>RTTSec=
</varname></term>
4157 <para>Specifies the RTT for the filter. Takes a timespan. Typical values are e.g.
100us for
4158 extremely high-performance
10GigE+ networks like datacentre,
1ms for non-WiFi LAN connections,
4159 100ms for typical internet connections. Defaults to unset, and the kernel's default will be used.
4165 <term><varname>AckFilter=
</varname></term>
4167 <para>Takes a boolean value, or special value
<literal>aggressive
</literal>. If enabled, ACKs in
4168 each flow are queued and redundant ACKs to the upstream are dropped. If yes, the filter will always
4169 keep at least two redundant ACKs in the queue, while in
<literal>aggressive
</literal> mode, it will
4170 filter down to a single ACK. This may improve download throughput on links with very asymmetrical
4171 rate limits. Defaults to unset, and the kernel's default will be used.
</para>
4179 <title>[ControlledDelay] Section Options
</title>
4180 <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
4181 controlled delay (CoDel).
</para>
4183 <variablelist class='network-directives'
>
4184 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4185 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4188 <term><varname>PacketLimit=
</varname></term>
4190 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4191 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
4192 kernel's default is used.
</para>
4197 <term><varname>TargetSec=
</varname></term>
4199 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
4200 Defaults to unset and kernel's default is used.
</para>
4205 <term><varname>IntervalSec=
</varname></term>
4207 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
4208 become too stale. Defaults to unset and kernel's default is used.
</para>
4213 <term><varname>ECN=
</varname></term>
4215 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
4216 unset and kernel's default is used.
</para>
4221 <term><varname>CEThresholdSec=
</varname></term>
4223 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
4224 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
4231 <title>[DeficitRoundRobinScheduler] Section Options
</title>
4232 <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
4233 Robin Scheduler (DRR).
</para>
4235 <variablelist class='network-directives'
>
4236 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4237 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4242 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
4243 <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
4244 Robin Scheduler (DRR).
</para>
4246 <variablelist class='network-directives'
>
4247 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
4248 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
4251 <term><varname>QuantumBytes=
</varname></term>
4253 <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
4254 to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
4255 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to the MTU of the
4264 <title>[EnhancedTransmissionSelection] Section Options
</title>
4265 <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
4266 Transmission Selection (ETS).
</para>
4268 <variablelist class='network-directives'
>
4269 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4270 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4273 <term><varname>Bands=
</varname></term>
4275 <para>Specifies the number of bands. An unsigned integer in the range
1…
16. This value has to be at
4276 least large enough to cover the strict bands specified through the
<varname>StrictBands=
</varname>
4277 and bandwidth-sharing bands specified in
<varname>QuantumBytes=
</varname>.
</para>
4282 <term><varname>StrictBands=
</varname></term>
4284 <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
4285 the range
1…
16.
</para>
4290 <term><varname>QuantumBytes=
</varname></term>
4292 <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
4293 suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
4294 respectively, to the base of
1024. This setting can be specified multiple times. If an empty
4295 string is assigned, then the all previous assignments are cleared.
</para>
4300 <term><varname>PriorityMap=
</varname></term>
4302 <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
4303 separated list of numbers. The first number indicates which band the packets with priority
0 should
4304 be put to, the second is for priority
1, and so on. There can be up to
16 numbers in the list. If
4305 there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
4306 the last one. Each band number must be in the range
0…
255. This setting can be specified multiple
4307 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
4314 <title>[GenericRandomEarlyDetection] Section Options
</title>
4315 <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
4316 Early Detection (GRED).
</para>
4318 <variablelist class='network-directives'
>
4319 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4320 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4323 <term><varname>VirtualQueues=
</varname></term>
4325 <para>Specifies the number of virtual queues. Takes an integer in the range
1…
16. Defaults to unset
4326 and kernel's default is used.
</para>
4331 <term><varname>DefaultVirtualQueue=
</varname></term>
4333 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
4334 Defaults to unset and kernel's default is used.
</para>
4339 <term><varname>GenericRIO=
</varname></term>
4341 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
4342 unset and kernel's default is used.
</para>
4349 <title>[FairQueueingControlledDelay] Section Options
</title>
4350 <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
4351 controlled delay (FQ-CoDel).
</para>
4353 <variablelist class='network-directives'
>
4354 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4355 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4358 <term><varname>PacketLimit=
</varname></term>
4360 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
4361 dropped. Defaults to unset and kernel's default is used.
</para>
4366 <term><varname>MemoryLimitBytes=
</varname></term>
4368 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
4369 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
4370 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
4375 <term><varname>Flows=
</varname></term>
4377 <para>Specifies the number of flows into which the incoming packets are classified.
4378 Defaults to unset and kernel's default is used.
</para>
4383 <term><varname>TargetSec=
</varname></term>
4385 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
4386 Defaults to unset and kernel's default is used.
</para>
4391 <term><varname>IntervalSec=
</varname></term>
4393 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
4394 become too stale. Defaults to unset and kernel's default is used.
</para>
4399 <term><varname>QuantumBytes=
</varname></term>
4401 <para>Specifies the number of bytes used as the
"deficit" in the fair queuing algorithm timespan.
4402 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
4403 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
4408 <term><varname>ECN=
</varname></term>
4410 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
4411 unset and kernel's default is used.
</para>
4416 <term><varname>CEThresholdSec=
</varname></term>
4418 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
4419 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
4426 <title>[FairQueueing] Section Options
</title>
4427 <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
4430 <variablelist class='network-directives'
>
4431 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4432 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4435 <term><varname>PacketLimit=
</varname></term>
4437 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
4438 dropped. Defaults to unset and kernel's default is used.
</para>
4443 <term><varname>FlowLimit=
</varname></term>
4445 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
4446 unset and kernel's default is used.
</para>
4451 <term><varname>QuantumBytes=
</varname></term>
4453 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
4454 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
4455 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
4456 default is used.
</para>
4461 <term><varname>InitialQuantumBytes=
</varname></term>
4463 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
4464 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
4465 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
4466 kernel's default is used.
</para>
4471 <term><varname>MaximumRate=
</varname></term>
4473 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
4474 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
4475 1000. Defaults to unset and kernel's default is used.
</para>
4480 <term><varname>Buckets=
</varname></term>
4482 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
4483 kernel's default is used.
</para>
4488 <term><varname>OrphanMask=
</varname></term>
4490 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
4491 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
4492 kernel's default is used.
</para>
4497 <term><varname>Pacing=
</varname></term>
4499 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
4500 default is used.
</para>
4505 <term><varname>CEThresholdSec=
</varname></term>
4507 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
4508 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
4515 <title>[TrivialLinkEqualizer] Section Options
</title>
4516 <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
4517 equalizer (teql).
</para>
4519 <variablelist class='network-directives'
>
4520 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4521 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4524 <term><varname>Id=
</varname></term>
4526 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
4527 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
4528 <constant>max_equalizers=N+
1</constant> option must be loaded before
4529 <command>systemd-networkd
</command> is started.
</para>
4536 <title>[HierarchyTokenBucket] Section Options
</title>
4537 <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
4538 bucket (htb).
</para>
4540 <variablelist class='network-directives'
>
4541 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4542 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4545 <term><varname>DefaultClass=
</varname></term>
4547 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
4548 to the class. Defaults to unset.
</para>
4553 <term><varname>RateToQuantum=
</varname></term>
4555 <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
4556 configured in
<varname>Rate=
</varname> by
<varname>RateToQuantum=
</varname>.
</para>
4563 <title>[HierarchyTokenBucketClass] Section Options
</title>
4564 <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
4567 <variablelist class='network-directives'
>
4568 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
4569 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
4572 <term><varname>Priority=
</varname></term>
4574 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
4575 priority field are tried for packets first.
</para>
4580 <term><varname>QuantumBytes=
</varname></term>
4582 <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
4583 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
4589 <term><varname>MTUBytes=
</varname></term>
4591 <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
4592 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
4597 <term><varname>OverheadBytes=
</varname></term>
4599 <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
4600 computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
4601 Megabytes, or Gigabytes, respectively, to the base of
1024.
</para>
4606 <term><varname>Rate=
</varname></term>
4608 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
4609 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
4610 to the base of
1000. This setting is mandatory.
</para>
4615 <term><varname>CeilRate=
</varname></term>
4617 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
4618 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
4619 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
4625 <term><varname>BufferBytes=
</varname></term>
4627 <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
4628 with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
4629 to the base of
1024.
</para>
4634 <term><varname>CeilBufferBytes=
</varname></term>
4636 <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
4637 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
4638 respectively, to the base of
1024.
</para>
4645 <title>[HeavyHitterFilter] Section Options
</title>
4646 <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
4649 <variablelist class='network-directives'
>
4650 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4651 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4654 <term><varname>PacketLimit=
</varname></term>
4656 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
4657 incoming packets are dropped. An unsigned integer in the range
0…
4294967294. Defaults to unset and
4658 kernel's default is used.
</para>
4665 <title>[QuickFairQueueing] Section Options
</title>
4666 <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
4669 <variablelist class='network-directives'
>
4670 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
4671 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
4676 <title>[QuickFairQueueingClass] Section Options
</title>
4677 <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
4680 <variablelist class='network-directives'
>
4681 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
4682 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
4685 <term><varname>Weight=
</varname></term>
4687 <para>Specifies the weight of the class. Takes an integer in the range
1…
1023. Defaults to
4688 unset in which case the kernel default is used.
</para>
4693 <term><varname>MaxPacketBytes=
</varname></term>
4695 <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the
4696 specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
4697 1024. When unset, the kernel default is used.
</para>
4704 <title>[BridgeVLAN] Section Options
</title>
4705 <para>The [BridgeVLAN] section manages the VLAN ID configuration of a bridge port and accepts the
4706 following keys. Specify several [BridgeVLAN] sections to configure several VLAN entries. The
4707 <varname>VLANFiltering=
</varname> option has to be enabled, see the [Bridge] section in
4708 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
4710 <variablelist class='network-directives'
>
4712 <term><varname>VLAN=
</varname></term>
4714 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. Takes
4715 an integer in the range
1…
4094.
</para>
4719 <term><varname>EgressUntagged=
</varname></term>
4721 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
4722 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
4723 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
4727 <term><varname>PVID=
</varname></term>
4729 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
4730 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
4731 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
4738 <title>Examples
</title>
4740 <title>Static network configuration
</title>
4742 <programlisting># /etc/systemd/network/
50-static.network
4747 Address=
192.168.0.15/
24
4748 Gateway=
192.168.0.1</programlisting>
4750 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
4751 specified gateway will be used for a default route.
</para>
4755 <title>DHCP on ethernet links
</title>
4757 <programlisting># /etc/systemd/network/
80-dhcp.network
4762 DHCP=yes
</programlisting>
4764 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
4765 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
4769 <title>IPv6 Prefix Delegation (DHCPv6 PD)
</title>
4771 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-upstream.network
4778 # The below setting is optional, to also assign an address in the delegated prefix
4779 # to the upstream interface. If not necessary, then comment out the line below and
4780 # the [DHCPPrefixDelegation] section.
4781 DHCPPrefixDelegation=yes
4783 # If the upstream network provides Router Advertisement with Managed bit set,
4784 # then comment out the line below and WithoutRA= setting in the [DHCPv6] section.
4790 [DHCPPrefixDelegation]
4791 UplinkInterface=:self
4793 Announce=no
</programlisting>
4795 <programlisting># /etc/systemd/network/
55-dhcpv6-pd-downstream.network
4800 DHCPPrefixDelegation=yes
4803 # It is expected that the host is acting as a router. So, usually it is not
4804 # necessary to receive Router Advertisement from other hosts in the downstream network.
4807 [DHCPPrefixDelegation]
4808 UplinkInterface=enp1s0
4810 Announce=yes
</programlisting>
4812 <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
4813 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
4814 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
4819 <title>IPv6 Prefix Delegation (DHCPv4
6RD)
</title>
4821 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-upstream.network
4828 # When DHCPv4-
6RD is used, the upstream network does not support IPv6.
4829 # Hence, it is not necessary to wait for Router Advertisement, which is enabled by default.
4833 Use6RD=yes
</programlisting>
4835 <programlisting># /etc/systemd/network/
55-dhcpv4-
6rd-downstream.network
4840 DHCPPrefixDelegation=yes
4843 # It is expected that the host is acting as a router. So, usually it is not
4844 # necessary to receive Router Advertisement from other hosts in the downstream network.
4847 [DHCPPrefixDelegation]
4848 UplinkInterface=enp1s0
4850 Announce=yes
</programlisting>
4852 <para>This will enable DHCPv4-
6RD on the interface enp1s0 as an upstream interface where the
4853 DHCPv4 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
4854 The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
4859 <title>A bridge with two enslaved links
</title>
4861 <programlisting># /etc/systemd/network/
25-bridge-static.netdev
4864 Kind=bridge
</programlisting>
4866 <programlisting># /etc/systemd/network/
25-bridge-static.network
4871 Address=
192.168.0.15/
24
4873 DNS=
192.168.0.1</programlisting>
4875 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
4880 Bridge=bridge0
</programlisting>
4882 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
4887 Bridge=bridge0
</programlisting>
4889 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
4890 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
4891 and network assigned, and a default route via the specified gateway will be
4892 added. The specified DNS server will be added to the global list of DNS resolvers.
4897 <title>Bridge port with VLAN forwarding
</title>
4900 # /etc/systemd/network/
25-bridge-slave-interface-
1.network
4916 EgressUntagged=
300-
400</programlisting>
4918 <para>This overrides the configuration specified in the previous example for the
4919 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
4920 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
4921 untagged when they leave on this interface. Untagged packets which arrive on this
4922 interface will be assigned VLAN ID
42.
</para>
4926 <title>Various tunnels
</title>
4928 <programlisting>/etc/systemd/network/
25-tunnels.network
4939 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
4945 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
4951 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
4957 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
4963 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
4964 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
4968 <title>A bond device
</title>
4970 <programlisting># /etc/systemd/network/
30-bond1.network
4978 <programlisting># /etc/systemd/network/
30-bond1.netdev
4984 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
4986 MACAddress=
52:
54:
00:e9:
64:
41
4992 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
4994 MACAddress=
52:
54:
00:e9:
64:
42
5000 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
5001 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
5002 will be used to acquire an address.
</para>
5006 <title>Virtual Routing and Forwarding (VRF)
</title>
5007 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
5008 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
5009 within the routing table defined during VRF creation. For kernels before
4.8 traffic
5010 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
5012 <programlisting># /etc/systemd/network/
25-vrf.network
5022 <title>MacVTap
</title>
5023 <para>This brings up a network interface
<literal>macvtap-test
</literal>
5024 and attaches it to
<literal>enp0s25
</literal>.
</para>
5025 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
5030 MACVTAP=macvtap-test
5035 <title>A Xfrm interface with physical underlying device.
</title>
5037 <programlisting># /etc/systemd/network/
27-xfrm.netdev
5043 InterfaceId=
7</programlisting>
5045 <programlisting># /etc/systemd/network/
27-eth0.network
5050 Xfrm=xfrm0
</programlisting>
5052 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
5053 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
5054 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
5060 <title>See Also
</title>
5062 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
5063 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
5064 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
5065 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
5066 <citerefentry><refentrytitle>systemd-network-generator.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
5067 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
projects / thirdparty / systemd.git / blob