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+ -->
6 <refentry id=
"systemd.network" conditional='ENABLE_NETWORKD'
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>systemd.network
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>systemd.network
</refentrytitle>
16 <manvolnum>5</manvolnum>
20 <refname>systemd.network
</refname>
21 <refpurpose>Network configuration
</refpurpose>
25 <para><filename><replaceable>network
</replaceable>.network
</filename></para>
29 <title>Description
</title>
31 <para>A plain ini-style text file that encodes network configuration for matching network interfaces,
33 <citerefentry><refentrytitle>systemd-networkd
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
34 See
<citerefentry><refentrytitle>systemd.syntax
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
35 for a general description of the syntax.
</para>
37 <para>The main network file must have the extension
<filename>.network
</filename>; other
38 extensions are ignored. Networks are applied to links whenever the links appear.
</para>
40 <para>The
<filename>.network
</filename> files are read from the files located in the system network
41 directories
<filename>/usr/lib/systemd/network
</filename> and
42 <filename>/usr/local/lib/systemd/network
</filename>, the volatile runtime network directory
43 <filename>/run/systemd/network
</filename> and the local administration network directory
44 <filename>/etc/systemd/network
</filename>. All configuration files are collectively sorted and processed
45 in lexical order, regardless of the directories in which they live. However, files with identical
46 filenames replace each other. Files in
<filename>/etc
</filename> have the highest priority, files in
47 <filename>/run
</filename> take precedence over files with the same name under
48 <filename>/usr
</filename>. This can be used to override a system-supplied configuration file with a local
49 file if needed. As a special case, an empty file (file size
0) or symlink with the same name pointing to
50 <filename>/dev/null
</filename> disables the configuration file entirely (it is
"masked").
</para>
52 <para>Along with the network file
<filename>foo.network
</filename>, a
"drop-in" directory
53 <filename>foo.network.d/
</filename> may exist. All files with the suffix
54 <literal>.conf
</literal> from this directory will be parsed after the file itself is
55 parsed. This is useful to alter or add configuration settings, without having to modify the main
56 configuration file. Each drop-in file must have appropriate section headers.
</para>
58 <para>In addition to
<filename>/etc/systemd/network
</filename>, drop-in
<literal>.d
</literal>
59 directories can be placed in
<filename>/usr/lib/systemd/network
</filename> or
60 <filename>/run/systemd/network
</filename> directories. Drop-in files in
61 <filename>/etc
</filename> take precedence over those in
<filename>/run
</filename> which in turn
62 take precedence over those in
<filename>/usr/lib
</filename>. Drop-in files under any of these
63 directories take precedence over the main network file wherever located.
</para>
65 <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6
66 nor IPv6LL enabled, shall be considered to have no IPv6 support. IPv6 will be automatically
67 disabled for that interface by writing
"1" to
68 <filename>/proc/sys/net/ipv6/conf/
<replaceable>ifname
</replaceable>/disable_ipv6
</filename>.
73 <title>[Match] Section Options
</title>
75 <para>The network file contains a
<literal>[Match]
</literal>
76 section, which determines if a given network file may be applied
77 to a given device; and a
<literal>[Network]
</literal> section
78 specifying how the device should be configured. The first (in
79 lexical order) of the network files that matches a given device
80 is applied, all later files are ignored, even if they match as
83 <para>A network file is said to match a network interface if all matches specified by the
84 <literal>[Match]
</literal> section are satisfied. When a network file does not contain valid
85 settings in
<literal>[Match]
</literal> section, then the file will match all interfaces and
86 <command>systemd-networkd
</command> warns about that. Hint: to avoid the warning and to make it
87 clear that all interfaces shall be matched, add the following:
88 <programlisting>Name=*
</programlisting>
89 The following keys are accepted:
</para>
91 <variablelist class='network-directives'
>
92 <xi:include href=
"systemd.link.xml" xpointer=
"mac-address" />
93 <xi:include href=
"systemd.link.xml" xpointer=
"permanent-mac-address" />
94 <xi:include href=
"systemd.link.xml" xpointer=
"path" />
95 <xi:include href=
"systemd.link.xml" xpointer=
"driver" />
96 <xi:include href=
"systemd.link.xml" xpointer=
"type" />
97 <xi:include href=
"systemd.link.xml" xpointer=
"property" />
100 <term><varname>Name=
</varname></term>
102 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
103 by the udev property
<literal>INTERFACE
</literal>, or device's alternative names. If the
104 list is prefixed with a
"!", the test is inverted.
</para>
109 <term><varname>WLANInterfaceType=
</varname></term>
111 <para>A whitespace-separated list of wireless network type. Supported values are
112 <literal>ad-hoc
</literal>,
<literal>station
</literal>,
<literal>ap
</literal>,
113 <literal>ap-vlan
</literal>,
<literal>wds
</literal>,
<literal>monitor
</literal>,
114 <literal>mesh-point
</literal>,
<literal>p2p-client
</literal>,
<literal>p2p-go
</literal>,
115 <literal>p2p-device
</literal>,
<literal>ocb
</literal>, and
<literal>nan
</literal>. If the
116 list is prefixed with a
"!", the test is inverted.
122 <term><varname>SSID=
</varname></term>
124 <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
125 connected wireless LAN. If the list is prefixed with a
"!", the test is inverted.
131 <term><varname>BSSID=
</varname></term>
133 <para>A whitespace-separated list of hardware address of the currently connected wireless
134 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
135 <varname>MACAddress=
</varname>. This option may appear more than one, in which case the
136 lists are merged. If the empty string is assigned to this option, the list of BSSID defined
137 prior to this is reset.
</para>
141 <xi:include href=
"systemd.link.xml" xpointer=
"host" />
142 <xi:include href=
"systemd.link.xml" xpointer=
"virtualization" />
143 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-command-line" />
144 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-version" />
145 <xi:include href=
"systemd.link.xml" xpointer=
"architecture" />
151 <title>[Link] Section Options
</title>
153 <para> The
<literal>[Link]
</literal> section accepts the following keys:
</para>
155 <variablelist class='network-directives'
>
157 <term><varname>MACAddress=
</varname></term>
159 <para>The hardware address to set for the device.
</para>
163 <term><varname>MTUBytes=
</varname></term>
165 <para>The maximum transmission unit in bytes to set for the
166 device. The usual suffixes K, M, G, are supported and are
167 understood to the base of
1024.
</para>
168 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
169 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
173 <term><varname>ARP=
</varname></term>
175 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
176 for this interface is enabled. When unset, the kernel's default will be used.
</para>
177 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
178 interfaces atop a single lower-level physical interface, which will then only serve as a
179 link/
"bridge" device aggregating traffic to the same physical link and not participate in
180 the network otherwise.
</para>
184 <term><varname>Multicast=
</varname></term>
186 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled.
</para>
190 <term><varname>AllMulticast=
</varname></term>
192 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the network.
193 This happens when multicast routing is enabled.
</para>
197 <term><varname>IPv6LinkLocalAddressGenerationMode=
</varname></term>
199 <para>Specifies how IPv6 link local address is generated. Takes one of
<literal>eui64
</literal>,
200 <literal>none
</literal>,
<literal>stable-privacy
</literal> and
<literal>random
</literal>.
201 When unset, the kernel's default will be used. Note that if
<varname>LinkLocalAdressing=
</varname>
202 not configured as
<literal>ipv6
</literal> then
<varname>IPv6LinkLocalAddressGenerationMode=
</varname>
207 <term><varname>Unmanaged=
</varname></term>
209 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are
210 made to bring up or configure matching links, equivalent to
211 when there are no matching network files. Defaults to
212 <literal>no
</literal>.
</para>
213 <para>This is useful for preventing later matching network
214 files from interfering with certain interfaces that are fully
215 controlled by other applications.
</para>
219 <term><varname>Group=
</varname></term>
221 <para>Link groups are similar to port ranges found in managed switches.
222 When network interfaces are added to a numbered group, operations on
223 all the interfaces from that group can be performed at once. An unsigned
224 integer ranges
0 to
4294967294. Default to unset.
</para>
228 <term><varname>RequiredForOnline=
</varname></term>
230 <para>Takes a boolean or a minimum operational state and an optional maximum operational state.
231 Please see
<citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
232 for possible operational states. When
<literal>yes
</literal>, the network is deemed required when
233 determining whether the system is online when running
234 <command>systemd-networkd-wait-online
</command>. When
<literal>no
</literal>, the network is ignored
235 when checking for online state. When a minimum operational state and an optional maximum operational
236 state are set,
<literal>yes
</literal> is implied, and this controls the minimum and maximum
237 operational state required for the network interface to be considered online.
238 Defaults to
<literal>yes
</literal>.
</para>
240 <para>The network will be brought up normally in all cases, but in
241 the event that there is no address being assigned by DHCP or the
242 cable is not plugged in, the link will simply remain offline and be
243 skipped automatically by
<command>systemd-networkd-wait-online
</command>
244 if
<literal>RequiredForOnline=no
</literal>.
</para>
251 <title>[Network] Section Options
</title>
253 <para>The
<literal>[Network]
</literal> section accepts the following keys:
</para>
255 <variablelist class='network-directives'
>
257 <term><varname>Description=
</varname></term>
259 <para>A description of the device. This is only used for
260 presentation purposes.
</para>
264 <term><varname>DHCP=
</varname></term>
266 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
267 <literal>yes
</literal>,
<literal>no
</literal>,
268 <literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults
269 to
<literal>no
</literal>.
</para>
271 <para>Note that DHCPv6 will by default be triggered by Router
272 Advertisement, if that is enabled, regardless of this parameter.
273 By enabling DHCPv6 support explicitly, the DHCPv6 client will
274 be started regardless of the presence of routers on the link,
275 or what flags the routers pass. See
276 <literal>IPv6AcceptRA=
</literal>.
</para>
278 <para>Furthermore, note that by default the domain name
279 specified through DHCP is not used for name resolution.
280 See option
<option>UseDomains=
</option> below.
</para>
282 <para>See the
<literal>[DHCPv4]
</literal> or
<literal>[DHCPv6]
</literal> section below for
283 further configuration options for the DHCP client support.
</para>
287 <term><varname>DHCPServer=
</varname></term>
289 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started. Defaults
290 to
<literal>no
</literal>. Further settings for the DHCP
291 server may be set in the
<literal>[DHCPServer]
</literal>
292 section described below.
</para>
296 <term><varname>LinkLocalAddressing=
</varname></term>
298 <para>Enables link-local address autoconfiguration. Accepts
<literal>yes
</literal>,
299 <literal>no
</literal>,
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
300 <literal>fallback
</literal>, or
<literal>ipv4-fallback
</literal>. If
301 <literal>fallback
</literal> or
<literal>ipv4-fallback
</literal> is specified, then an IPv4
302 link-local address is configured only when DHCPv4 fails. If
<literal>fallback
</literal>,
303 an IPv6 link-local address is always configured, and if
<literal>ipv4-fallback
</literal>,
304 the address is not configured. Note that, the fallback mechanism works only when DHCPv4
305 client is enabled, that is, it requires
<literal>DHCP=yes
</literal> or
306 <literal>DHCP=ipv4
</literal>. If
<varname>Bridge=
</varname> is set, defaults to
307 <literal>no
</literal>, and if not, defaults to
<literal>ipv6
</literal>.
312 <term><varname>IPv4LLRoute=
</varname></term>
314 <para>Takes a boolean. If set to true, sets up the route needed for
315 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
321 <term><varname>DefaultRouteOnDevice=
</varname></term>
323 <para>Takes a boolean. If set to true, sets up the default route bound to the interface.
324 Defaults to false. This is useful when creating routes on point-to-point interfaces.
325 This is equivalent to e.g. the following.
326 <programlisting>ip route add default dev veth99
</programlisting></para>
330 <term><varname>IPv6Token=
</varname></term>
332 <para>Specifies an optional address generation mode and a required IPv6 address. If
333 the mode is present, the two parts must be separated with a colon
334 <literal><replaceable>mode
</replaceable>:
<replaceable>address
</replaceable></literal>. The
335 address generation mode may be either
<constant>prefixstable
</constant> or
336 <constant>static
</constant>. If not specified,
<constant>static
</constant> is assumed.
338 <para>When the mode is set to
<constant>static
</constant>, or unspecified, the lower bits of
339 the supplied address are combined with the upper bits of a prefix received in a Router Advertisement
340 message to form a complete address. Note that if multiple prefixes are received in an RA message, or in
341 multiple RA messages, addresses will be formed from each of them using the supplied address. This
342 mode implements SLAAC but uses a static interface identifier instead of an identifier generated
343 using the EUI-
64 algorithm. Because the interface identifier is static, if Duplicate Address Detection
344 detects that the computed address is a duplicate (in use by another node on the link), then this
345 mode will fail to provide an address for that prefix.
347 <para>When the mode is set to
<literal>prefixstable
</literal> the RFC
7217 algorithm for generating
348 interface identifiers will be used, but only when a prefix received in an RA message matches the supplied address.
349 See
<ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink>. Prefix matching will be attempted
350 against each
<constant>prefixstable
</constant> IPv6Token variable provided in the configuration; if a received
351 prefix does not match any of the provided addresses, then the EUI-
64 algorithm will be used to form
352 an interface identifier for that prefix. This mode is also SLAAC, but with a potentially stable interface
353 identifier which does not directly map to the interface's hardware address.
355 Note that the
<constant>prefixstable
</constant> algorithm includes both the interface's name and
356 MAC address in the hash used to compute the interface identifier, so if either of those are changed the resulting
357 interface identifier (and address) will change, even if the prefix received in the RA message has not changed.
359 Note that if multiple
<constant>prefixstable
</constant> IPv6Token variables are supplied with addresses that
360 match a prefix received in an RA message, only the first one will be used to generate addresses.
365 <term><varname>LLMNR=
</varname></term>
367 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
369 url=
"https://tools.ietf.org/html/rfc4795">Link-Local
370 Multicast Name Resolution
</ulink> on the link. When set to
371 <literal>resolve
</literal>, only resolution is enabled,
372 but not host registration and announcement. Defaults to
373 true. This setting is read by
374 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
378 <term><varname>MulticastDNS=
</varname></term>
380 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
382 url=
"https://tools.ietf.org/html/rfc6762">Multicast
383 DNS
</ulink> support on the link. When set to
384 <literal>resolve
</literal>, only resolution is enabled,
385 but not host or service registration and
386 announcement. Defaults to false. This setting is read by
387 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
391 <term><varname>DNSOverTLS=
</varname></term>
393 <para>Takes a boolean or
<literal>opportunistic
</literal>.
396 url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink>
398 When set to
<literal>opportunistic
</literal>, compatibility with
399 non-DNS-over-TLS servers is increased, by automatically
400 turning off DNS-over-TLS servers in this case.
401 This option defines a per-interface setting for
402 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
403 global
<varname>DNSOverTLS=
</varname> option. Defaults to
404 false. This setting is read by
405 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
409 <term><varname>DNSSEC=
</varname></term>
411 <para>Takes a boolean. or
412 <literal>allow-downgrade
</literal>. When true, enables
414 url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink>
415 DNS validation support on the link. When set to
416 <literal>allow-downgrade
</literal>, compatibility with
417 non-DNSSEC capable networks is increased, by automatically
418 turning off DNSSEC in this case. This option defines a
419 per-interface setting for
420 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
421 global
<varname>DNSSEC=
</varname> option. Defaults to
422 false. This setting is read by
423 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
427 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
428 <listitem><para>A space-separated list of DNSSEC negative
429 trust anchor domains. If specified and DNSSEC is enabled,
430 look-ups done via the interface's DNS server will be subject
431 to the list of negative trust anchors, and not require
432 authentication for the specified domains, or anything below
433 it. Use this to disable DNSSEC authentication for specific
434 private domains, that cannot be proven valid using the
435 Internet DNS hierarchy. Defaults to the empty list. This
437 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
441 <term><varname>LLDP=
</varname></term>
443 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
444 implemented on professional routers and bridges which announces which physical port a system is connected
445 to, as well as other related data. Accepts a boolean or the special value
446 <literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
447 neighbors maintained. If
<literal>routers-only
</literal> is set only LLDP data of various types of routers
448 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
449 others). If false, LLDP reception is disabled. Defaults to
<literal>routers-only
</literal>. Use
450 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
451 collected neighbor data. LLDP is only available on Ethernet links. See
<varname>EmitLLDP=
</varname> below
452 for enabling LLDP packet emission from the local system.
457 <term><varname>EmitLLDP=
</varname></term>
459 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
460 <literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
461 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
462 a short LLDP packet with information about the local system is sent out in regular intervals on the
463 link. The LLDP packet will contain information about the local hostname, the local machine ID (as stored
464 in
<citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
465 local interface name, as well as the pretty hostname of the system (as set in
466 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
467 emission is only available on Ethernet links. Note that this setting passes data suitable for
468 identification of host to the network and should thus not be enabled on untrusted networks, where such
469 identification data should not be made available. Use this option to permit other systems to identify on
470 which interfaces they are connected to this system. The three special values control propagation of the
471 LLDP packets. The
<literal>nearest-bridge
</literal> setting permits propagation only to the nearest
472 connected bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays, but
473 not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until a customer bridge
474 is reached. For details about these concepts, see
<ulink
475 url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>. Note that
476 configuring this setting to true is equivalent to
<literal>nearest-bridge
</literal>, the recommended and
477 most restricted level of propagation. See
<varname>LLDP=
</varname> above for an option to enable LLDP
483 <term><varname>BindCarrier=
</varname></term>
485 <para>A link name or a list of link names. When set, controls the behavior of the current
486 link. When all links in the list are in an operational down state, the current link is brought
487 down. When at least one link has carrier, the current interface is brought up.
492 <term><varname>Address=
</varname></term>
494 <para>A static IPv4 or IPv6 address and its prefix length,
495 separated by a
<literal>/
</literal> character. Specify
496 this key more than once to configure several addresses.
497 The format of the address must be as described in
498 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
499 This is a short-hand for an [Address] section only
500 containing an Address key (see below). This option may be
501 specified more than once.
504 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
505 (for IPv6), a new address range of the requested size is automatically allocated from a
506 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
507 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
508 all known network configuration files to avoid address range conflicts. The default system-wide
509 pool consists of
192.168.0.0/
16,
172.16.0.0/
12 and
10.0.0.0/
8 for IPv4, and fd00::/
8 for IPv6.
510 This functionality is useful to manage a large number of dynamically created network interfaces
511 with the same network configuration and automatic address range assignment.
</para>
516 <term><varname>Gateway=
</varname></term>
518 <para>The gateway address, which must be in the format
520 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
521 This is a short-hand for a [Route] section only containing
522 a Gateway key. This option may be specified more than
527 <term><varname>DNS=
</varname></term>
529 <para>A DNS server address, which must be in the format
531 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
532 This option may be specified more than once. This setting is read by
533 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
537 <term><varname>Domains=
</varname></term>
539 <para>A whitespace-separated list of domains which should be resolved using the DNS servers on
540 this link. Each item in the list should be a domain name, optionally prefixed with a tilde
541 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
542 domains without the prefix are called
"search domains" and are first used as search suffixes for
543 extending single-label hostnames (hostnames containing no dots) to become fully qualified
544 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
545 specified search domains are appended to it in turn, converting it into a fully qualified domain
546 name, until one of them may be successfully resolved.
</para>
548 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for hostnames
549 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
550 the DNS servers configured for this interface. The domain routing logic is particularly useful on
551 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
553 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
554 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
555 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
556 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
557 if a link on which they are connected is available.
</para>
559 <para>This setting is read by
560 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
561 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
562 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
563 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
564 name servers limited to a specific link.
</para>
568 <term><varname>DNSDefaultRoute=
</varname></term>
570 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
571 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
572 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
573 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
574 queries not matching any link's configured domains will be routed to this link if it has no routing-only
575 domains configured.
</para>
579 <term><varname>NTP=
</varname></term>
581 <para>An NTP server address. This option may be specified more than once. This setting is read by
582 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
586 <term><varname>IPForward=
</varname></term>
587 <listitem><para>Configures IP packet forwarding for the
588 system. If enabled, incoming packets on any network
589 interface will be forwarded to any other interfaces
590 according to the routing table. Takes a boolean,
591 or the values
<literal>ipv4
</literal> or
592 <literal>ipv6
</literal>, which only enable IP packet
593 forwarding for the specified address family. This controls
594 the
<filename>net.ipv4.ip_forward
</filename> and
595 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
596 options of the network interface (see
<ulink
597 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
598 for details about sysctl options). Defaults to
599 <literal>no
</literal>.
</para>
601 <para>Note: this setting controls a global kernel option,
602 and does so one way only: if a network that has this setting
603 enabled is set up the global setting is turned on. However,
604 it is never turned off again, even after all networks with
605 this setting enabled are shut down again.
</para>
607 <para>To allow IP packet forwarding only between specific
608 network interfaces use a firewall.
</para>
612 <term><varname>IPMasquerade=
</varname></term>
613 <listitem><para>Configures IP masquerading for the network
614 interface. If enabled, packets forwarded from the network
615 interface will be appear as coming from the local host.
616 Takes a boolean argument. Implies
617 <varname>IPForward=ipv4
</varname>. Defaults to
618 <literal>no
</literal>.
</para></listitem>
621 <term><varname>IPv6PrivacyExtensions=
</varname></term>
622 <listitem><para>Configures use of stateless temporary
623 addresses that change over time (see
<ulink
624 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
625 Privacy Extensions for Stateless Address Autoconfiguration
626 in IPv6). Takes a boolean or the special values
627 <literal>prefer-public
</literal> and
628 <literal>kernel
</literal>. When true, enables the privacy
629 extensions and prefers temporary addresses over public
630 addresses. When
<literal>prefer-public
</literal>, enables the
631 privacy extensions, but prefers public addresses over
632 temporary addresses. When false, the privacy extensions
633 remain disabled. When
<literal>kernel
</literal>, the kernel's
634 default setting will be left in place. Defaults to
635 <literal>no
</literal>.
</para></listitem>
638 <term><varname>IPv6AcceptRA=
</varname></term>
639 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
640 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they may
641 trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or if no
642 routers are found on the link. The default is to disable RA reception for bridge devices or when IP
643 forwarding is enabled, and to enable it otherwise. Cannot be enabled on bond devices and when link
644 local addressing is disabled.
</para>
646 <para>Further settings for the IPv6 RA support may be configured in the
647 <literal>[IPv6AcceptRA]
</literal> section, see below.
</para>
649 <para>Also see
<ulink
650 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink> in the kernel
651 documentation regarding
<literal>accept_ra
</literal>, but note that systemd's setting of
652 <constant>1</constant> (i.e. true) corresponds to kernel's setting of
<constant>2</constant>.
</para>
654 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
655 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
656 RA protocol is used, and the kernel's own implementation remains disabled, since
657 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
658 and these are not available from the kernel if the kernel's own implementation is used.
</para>
662 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
663 <listitem><para>Configures the amount of IPv6 Duplicate
664 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
668 <term><varname>IPv6HopLimit=
</varname></term>
669 <listitem><para>Configures IPv6 Hop Limit. For each router that
670 forwards the packet, the hop limit is decremented by
1. When the
671 hop limit field reaches zero, the packet is discarded.
672 When unset, the kernel's default will be used.
676 <term><varname>IPv4ProxyARP=
</varname></term>
677 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
678 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
679 the router accepts responsibility for routing packets to the
"real" destination. (see
<ulink
680 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
681 When unset, the kernel's default will be used.
685 <term><varname>IPv6ProxyNDP=
</varname></term>
686 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
687 Protocol) is a technique for IPv6 to allow routing of addresses to a different
688 destination when peers expect them to be present on a certain physical link.
689 In this case a router answers Neighbour Advertisement messages intended for
690 another machine by offering its own MAC address as destination.
691 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
692 Advertisement messages for addresses in the IPv6 neighbor proxy table,
693 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
694 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
695 interface depending on this option.
696 When unset, the kernel's default will be used.
700 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
701 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
702 proxied. This option may be specified more than once. systemd-networkd will add the
703 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
704 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
705 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
709 <term><varname>IPv6PrefixDelegation=
</varname></term>
710 <listitem><para>Whether to enable or disable Router Advertisement sending on a link.
711 Allowed values are
<literal>static
</literal> which distributes prefixes as defined in
712 the
<literal>[IPv6PrefixDelegation]
</literal> and any
<literal>[IPv6Prefix]
</literal>
713 sections,
<literal>dhcpv6
</literal> which requests prefixes using a DHCPv6 client
714 configured for another link and any values configured in the
715 <literal>[IPv6PrefixDelegation]
</literal> section while ignoring all static prefix
716 configuration sections,
<literal>yes
</literal> which uses both static configuration
717 and DHCPv6, and
<literal>false
</literal> which turns off IPv6 prefix delegation
718 altogether. Defaults to
<literal>false
</literal>. See the
719 <literal>[IPv6PrefixDelegation]
</literal> and the
<literal>[IPv6Prefix]
</literal>
720 sections for more configuration options.
724 <term><varname>IPv6PDSubnetId=
</varname></term>
725 <listitem><para>Configure a specific subnet ID on the interface from a (previously) received prefix delegation.
726 You can either set
"auto" (the default) or a specific subnet ID
727 (as defined in
<ulink url=
"https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC
4291</ulink>, section
2.5.4),
728 in which case the allowed value is hexadecimal, from
0 to
0x7fffffffffffffff inclusive.
729 This option is only effective when used together with
<varname>IPv6PrefixDelegation=
</varname>
730 and the corresponding configuration on the upstream interface.
734 <term><varname>IPv6MTUBytes=
</varname></term>
735 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
736 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
740 <term><varname>Bridge=
</varname></term>
742 <para>The name of the bridge to add the link to. See
743 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
748 <term><varname>Bond=
</varname></term>
750 <para>The name of the bond to add the link to. See
751 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
756 <term><varname>VRF=
</varname></term>
758 <para>The name of the VRF to add the link to. See
759 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
764 <term><varname>VLAN=
</varname></term>
766 <para>The name of a VLAN to create on the link. See
767 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
768 This option may be specified more than once.
</para>
772 <term><varname>IPVLAN=
</varname></term>
774 <para>The name of a IPVLAN to create on the link. See
775 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
776 This option may be specified more than once.
</para>
780 <term><varname>MACVLAN=
</varname></term>
782 <para>The name of a MACVLAN to create on the link. See
783 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
784 This option may be specified more than once.
</para>
788 <term><varname>VXLAN=
</varname></term>
790 <para>The name of a VXLAN to create on the link. See
791 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
792 This option may be specified more than once.
</para>
796 <term><varname>Tunnel=
</varname></term>
798 <para>The name of a Tunnel to create on the link. See
799 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
800 This option may be specified more than once.
</para>
804 <term><varname>MACsec=
</varname></term>
806 <para>The name of a MACsec device to create on the link. See
807 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
808 This option may be specified more than once.
</para>
812 <term><varname>ActiveSlave=
</varname></term>
814 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
815 option is only valid for following modes:
816 <literal>active-backup
</literal>,
817 <literal>balance-alb
</literal> and
818 <literal>balance-tlb
</literal>. Defaults to false.
823 <term><varname>PrimarySlave=
</varname></term>
825 <para>Takes a boolean. Specifies which slave is the primary device. The specified
826 device will always be the active slave while it is available. Only when the
827 primary is off-line will alternate devices be used. This is useful when
828 one slave is preferred over another, e.g. when one slave has higher throughput
829 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
831 <literal>active-backup
</literal>,
832 <literal>balance-alb
</literal> and
833 <literal>balance-tlb
</literal>. Defaults to false.
838 <term><varname>ConfigureWithoutCarrier=
</varname></term>
840 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
846 <term><varname>IgnoreCarrierLoss=
</varname></term>
848 <para>A boolean. Allows networkd to retain both the static and dynamic configuration of the
849 interface even if its carrier is lost. Defaults to false.
854 <term><varname>Xfrm=
</varname></term>
856 <para>The name of the xfrm to create on the link. See
857 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
858 This option may be specified more than once.
</para>
862 <term><varname>KeepConfiguration=
</varname></term>
864 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
865 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
866 will not drop static addresses and routes on starting up process. When set to
867 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
868 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
869 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
870 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
871 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
872 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
873 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
<literal>no
</literal>.
883 <title>[Address] Section Options
</title>
885 <para>An
<literal>[Address]
</literal> section accepts the
886 following keys. Specify several
<literal>[Address]
</literal>
887 sections to configure several addresses.
</para>
889 <variablelist class='network-directives'
>
891 <term><varname>Address=
</varname></term>
893 <para>As in the
<literal>[Network]
</literal> section. This key is mandatory. Each
894 <literal>[Address]
</literal> section can contain one
<varname>Address=
</varname> setting.
</para>
898 <term><varname>Peer=
</varname></term>
900 <para>The peer address in a point-to-point connection.
901 Accepts the same format as the
<varname>Address=
</varname>
906 <term><varname>Broadcast=
</varname></term>
908 <para>The broadcast address, which must be in the format
910 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
911 This key only applies to IPv4 addresses. If it is not
912 given, it is derived from the
<varname>Address=
</varname>
917 <term><varname>Label=
</varname></term>
919 <para>An address label.
</para>
923 <term><varname>PreferredLifetime=
</varname></term>
925 <para>Allows the default
"preferred lifetime" of the address to be overridden.
926 Only three settings are accepted:
<literal>forever
</literal> or
<literal>infinity
</literal>
927 which is the default and means that the address never expires, and
<literal>0</literal> which means
928 that the address is considered immediately
"expired" and will not be used,
929 unless explicitly requested. A setting of PreferredLifetime=
0 is useful for
930 addresses which are added to be used only by a specific application,
931 which is then configured to use them explicitly.
</para>
935 <term><varname>Scope=
</varname></term>
937 <para>The scope of the address, which can be
<literal>global
</literal>,
938 <literal>link
</literal> or
<literal>host
</literal> or an unsigned integer ranges
0 to
255.
939 Defaults to
<literal>global
</literal>.
</para>
943 <term><varname>HomeAddress=
</varname></term>
945 <para>Takes a boolean. Designates this address the
"home address" as defined in
946 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
947 Supported only on IPv6. Defaults to false.
</para>
951 <term><varname>DuplicateAddressDetection=
</varname></term>
953 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
954 <literal>both
</literal>,
<literal>none
</literal>. When
<literal>ipv4
</literal>,
955 performs IPv4 Duplicate Address Detection. See
956 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
957 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
958 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>.
959 Defaults to
<literal>ipv6
</literal>.
</para>
963 <term><varname>ManageTemporaryAddress=
</varname></term>
965 <para>Takes a boolean. If true the kernel manage temporary addresses created
966 from this one as template on behalf of Privacy Extensions
967 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
968 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
969 The given address needs to have a prefix length of
64. This flag allows using privacy
970 extensions in a manually configured network, just like if stateless auto-configuration
971 was active. Defaults to false.
</para>
975 <term><varname>AddPrefixRoute=
</varname></term>
977 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
978 Defaults to true.
</para>
982 <term><varname>AutoJoin=
</varname></term>
984 <para>Takes a boolean. Joining multicast group on ethernet level via
985 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
986 IGMP snooping since the switch would not replicate multicast packets on ports that did not
987 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
988 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
989 that enables then to do the required join. By extending ip address command with option
990 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
991 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
992 Defaults to
<literal>no
</literal>.
</para>
999 <title>[Neighbor] Section Options
</title>
1000 <para>A
<literal>[Neighbor]
</literal> section accepts the
1001 following keys. The neighbor section adds a permanent, static
1002 entry to the neighbor table (IPv6) or ARP table (IPv4) for
1003 the given hardware address on the links matched for the network.
1004 Specify several
<literal>[Neighbor]
</literal> sections to configure
1005 several static neighbors.
</para>
1007 <variablelist class='network-directives'
>
1009 <term><varname>Address=
</varname></term>
1011 <para>The IP address of the neighbor.
</para>
1015 <term><varname>LinkLayerAddress=
</varname></term>
1017 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
1024 <title>[IPv6AddressLabel] Section Options
</title>
1026 <para>An
<literal>[IPv6AddressLabel]
</literal> section accepts the
1027 following keys. Specify several
<literal>[IPv6AddressLabel]
</literal>
1028 sections to configure several address labels. IPv6 address labels are
1029 used for address selection. See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>.
1030 Precedence is managed by userspace, and only the label itself is stored in the kernel
</para>
1032 <variablelist class='network-directives'
>
1034 <term><varname>Label=
</varname></term>
1036 <para> The label for the prefix (an unsigned integer) ranges
0 to
4294967294.
1037 0xffffffff is reserved. This key is mandatory.
</para>
1041 <term><varname>Prefix=
</varname></term>
1043 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
1044 This key is mandatory.
</para>
1051 <title>[RoutingPolicyRule] Section Options
</title>
1053 <para>An
<literal>[RoutingPolicyRule]
</literal> section accepts the
1054 following keys. Specify several
<literal>[RoutingPolicyRule]
</literal>
1055 sections to configure several rules.
</para>
1057 <variablelist class='network-directives'
>
1059 <term><varname>TypeOfService=
</varname></term>
1061 <para>Specifies the type of service to match a number between
0 to
255.
</para>
1065 <term><varname>From=
</varname></term>
1067 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1071 <term><varname>To=
</varname></term>
1073 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1077 <term><varname>FirewallMark=
</varname></term>
1079 <para>Specifies the iptables firewall mark value to match (a number between
1 and
4294967295).
</para>
1083 <term><varname>Table=
</varname></term>
1085 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes
1086 one of
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
1087 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1091 <term><varname>Priority=
</varname></term>
1093 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1094 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1098 <term><varname>IncomingInterface=
</varname></term>
1100 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1104 <term><varname>OutgoingInterface=
</varname></term>
1106 <para>Specifies the outgoing device to match. The outgoing interface is only available for packets originating from local sockets that are bound to a device.
</para>
1110 <term><varname>SourcePort=
</varname></term>
1112 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1113 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1117 <term><varname>DestinationPort=
</varname></term>
1119 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1120 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1124 <term><varname>IPProtocol=
</varname></term>
1126 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1127 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1128 <literal>17</literal> for
<literal>udp
</literal>.
1129 Defaults to unset.
</para>
1133 <term><varname>InvertRule=
</varname></term>
1135 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1139 <term><varname>Family=
</varname></term>
1141 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1142 <literal>both
</literal>. By default, the address family is determined by the address
1143 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1144 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1145 <literal>ipv4
</literal>.
</para>
1149 <term><varname>User=
</varname></term>
1151 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1156 <term><varname>SuppressPrefixLength=
</varname></term>
1158 <para>Takes a number
<replaceable>N
</replaceable> in the range
0-
128 and rejects routing
1159 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1167 <title>[NextHop] Section Options
</title>
1168 <para>The
<literal>[NextHop]
</literal> section accepts the
1169 following keys. Specify several
<literal>[NextHop]
</literal>
1170 sections to configure several nexthop. Nexthop is used to manipulate entries in the kernel's nexthop
1173 <variablelist class='network-directives'
>
1175 <term><varname>Gateway=
</varname></term>
1177 <para>As in the
<literal>[Network]
</literal> section. This is mandatory.
</para>
1181 <term><varname>Id=
</varname></term>
1183 <para>The id of the nexthop (an unsigned integer). If unspecified or '
0' then automatically chosen by kernel.
</para>
1190 <title>[Route] Section Options
</title>
1191 <para>The
<literal>[Route]
</literal> section accepts the
1192 following keys. Specify several
<literal>[Route]
</literal>
1193 sections to configure several routes.
</para>
1195 <variablelist class='network-directives'
>
1197 <term><varname>Gateway=
</varname></term>
1199 <para>Takes the gateway address or special value
<literal>_dhcp
</literal>. If
1200 <literal>_dhcp
</literal>, then the gateway address provided by DHCP (or in the IPv6 case,
1201 provided by IPv6 RA) is used.
</para>
1205 <term><varname>GatewayOnLink=
</varname></term>
1207 <para>Takes a boolean. If set to true, the kernel does not have
1208 to check if the gateway is reachable directly by the current machine (i.e., the kernel does
1209 not need to check if the gateway is attached to the local network), so that we can insert the
1210 route in the kernel table without it being complained about. Defaults to
<literal>no
</literal>.
1215 <term><varname>Destination=
</varname></term>
1217 <para>The destination prefix of the route. Possibly
1218 followed by a slash and the prefix length. If omitted, a
1219 full-length host route is assumed.
</para>
1223 <term><varname>Source=
</varname></term>
1225 <para>The source prefix of the route. Possibly followed by
1226 a slash and the prefix length. If omitted, a full-length
1227 host route is assumed.
</para>
1231 <term><varname>Metric=
</varname></term>
1233 <para>The metric of the route (an unsigned integer).
</para>
1237 <term><varname>IPv6Preference=
</varname></term>
1239 <para>Specifies the route preference as defined in
<ulink
1240 url=
"https://tools.ietf.org/html/rfc4191">RFC4191
</ulink> for Router Discovery messages.
1241 Which can be one of
<literal>low
</literal> the route has a lowest priority,
1242 <literal>medium
</literal> the route has a default priority or
1243 <literal>high
</literal> the route has a highest priority.
</para>
1247 <term><varname>Scope=
</varname></term>
1249 <para>The scope of the route, which can be
<literal>global
</literal>,
<literal>site
</literal>,
1250 <literal>link
</literal>,
<literal>host
</literal>, or
<literal>nowhere
</literal>. For IPv4 route,
1251 defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
<literal>local
</literal>
1252 or
<literal>nat
</literal>, and
<literal>link
</literal> if
<varname>Type=
</varname> is
1253 <literal>broadcast
</literal>,
<literal>multicast
</literal>, or
<literal>anycast
</literal>.
1254 In other cases, defaults to
<literal>global
</literal>.
</para>
1258 <term><varname>PreferredSource=
</varname></term>
1260 <para>The preferred source address of the route. The address
1261 must be in the format described in
1262 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1266 <term><varname>Table=
</varname></term>
1268 <para>The table identifier for the route. Takes
<literal>default
</literal>,
1269 <literal>main
</literal>,
<literal>local
</literal> or a number between
1 and
4294967295.
1270 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1271 If unset and
<varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1272 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1273 In other cases, defaults to
<literal>main
</literal>.
1278 <term><varname>Protocol=
</varname></term>
1280 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1281 <literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1282 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1287 <term><varname>Type=
</varname></term>
1289 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1290 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1291 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1292 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1293 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1294 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1295 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1296 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1297 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1298 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1299 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1304 <term><varname>InitialCongestionWindow=
</varname></term>
1306 <para>The TCP initial congestion window is used during the start of a TCP connection. During the start of a TCP
1307 session, when a client requests a resource, the server's initial congestion window determines how many data bytes
1308 will be sent during the initial burst of data. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual
1309 suffixes K, M, G are supported and are understood to the base of
1024. When unset, the kernel's default will be used.
1314 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1316 <para>The TCP initial advertised receive window is the amount of receive data (in bytes) that can initially be buffered at one time
1317 on a connection. The sending host can send only that amount of data before waiting for an acknowledgment and window update
1318 from the receiving host. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual suffixes K, M, G are supported
1319 and are understood to the base of
1024. When unset, the kernel's default will be used.
1324 <term><varname>QuickAck=
</varname></term>
1326 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1331 <term><varname>FastOpenNoCookie=
</varname></term>
1333 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1334 When unset, the kernel's default will be used.
1339 <term><varname>TTLPropagate=
</varname></term>
1341 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1342 When unset, the kernel's default will be used.
1347 <term><varname>MTUBytes=
</varname></term>
1349 <para>The maximum transmission unit in bytes to set for the
1350 route. The usual suffixes K, M, G, are supported and are
1351 understood to the base of
1024.
</para>
1352 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1353 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1357 <term><varname>IPServiceType=
</varname></term>
1359 <para>Takes string;
<literal>CS6
</literal> or
<literal>CS4
</literal>. Used to set IP
1360 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.
</para>
1364 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1366 <para>Configures multipath route. Multipath routing is the technique of using multiple
1367 alternative paths through a network. Takes gateway address. Optionally, takes a network
1368 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for
1369 this multipath route separated with whitespace. This setting can be specified multiple
1370 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
1377 <title>[DHCPv4] Section Options
</title>
1378 <para>The
<literal>[DHCPv4]
</literal> section configures the
1379 DHCPv4 client, if it is enabled with the
1380 <varname>DHCP=
</varname> setting described above:
</para>
1382 <variablelist class='network-directives'
>
1384 <term><varname>UseDNS=
</varname></term>
1386 <para>When true (the default), the DNS servers received
1387 from the DHCP server will be used and take precedence over
1388 any statically configured ones.
</para>
1390 <para>This corresponds to the
<option>nameserver
</option>
1391 option in
<citerefentry
1392 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1396 <term><varname>RoutesToDNS=
</varname></term>
1398 <para>When true, the routes to the DNS servers received from the DHCP server will be
1399 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored.
1400 Defaults to false.
</para>
1404 <term><varname>UseNTP=
</varname></term>
1406 <para>When true (the default), the NTP servers received
1407 from the DHCP server will be used by systemd-timesyncd
1408 and take precedence over any statically configured ones.
</para>
1412 <term><varname>UseSIP=
</varname></term>
1414 <para>When true (the default), the SIP servers received
1415 from the DHCP server will be saved at the state files and can be
1416 read via
<function>sd_network_link_get_sip_servers()
</function> function.
</para>
1421 <term><varname>UseMTU=
</varname></term>
1423 <para>When true, the interface maximum transmission unit
1424 from the DHCP server will be used on the current link.
1425 If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
1426 Defaults to false.
</para>
1430 <term><varname>Anonymize=
</varname></term>
1432 <para>Takes a boolean. When true, the options sent to the DHCP server will
1433 follow the
<ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink>
1434 (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying information.
1435 Defaults to false.
</para>
1437 <para>This option should only be set to true when
1438 <varname>MACAddressPolicy=
</varname> is set to
<literal>random
</literal>
1440 project='man-pages'
><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
1442 <para>Note that this configuration will overwrite others.
1443 In concrete, the following variables will be ignored:
1444 <varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1445 <varname>UseRoutes=
</varname>,
<varname>UseMTU=
</varname>,
1446 <varname>VendorClassIdentifier=
</varname>,
<varname>UseTimezone=
</varname>.
</para>
1448 <para>With this option enabled DHCP requests will mimic those generated by Microsoft Windows, in
1449 order to reduce the ability to fingerprint and recognize installations. This means DHCP request
1450 sizes will grow and lease data will be more comprehensive than normally, though most of the
1451 requested data is not actually used.
</para>
1455 <term><varname>SendHostname=
</varname></term>
1457 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1458 Note that the machine's hostname must consist only of
7-bit ASCII lower-case characters and
1459 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1460 sent even if this is set to true.
</para>
1465 <term><varname>MUDURL=
</varname></term>
1467 <para>When configured, the Manufacturer Usage Descriptions (MUD) URL will be sent to the
1468 DHCPv4 server. Takes an URL of length up to
255 characters. A superficial verification that
1469 the string is a valid URL will be performed. DHCPv4 clients are intended to have at most one
1470 MUD URL associated with them. See
1471 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
1476 <term><varname>UseHostname=
</varname></term>
1478 <para>When true (the default), the hostname received from
1479 the DHCP server will be set as the transient hostname of the system.
1484 <term><varname>Hostname=
</varname></term>
1486 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1487 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1488 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1492 <term><varname>UseDomains=
</varname></term>
1494 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1495 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1496 the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name received from
1497 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1498 the
<option>Domains=
</option> setting when the argument is prefixed with
<literal>~
</literal>. Defaults to
1501 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1502 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
1503 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1504 single-label names.
</para>
1506 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1507 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1511 <term><varname>UseRoutes=
</varname></term>
1513 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1514 routing table with a metric of
1024, and a scope of
"global",
"link" or
"host", depending on the route's
1515 destination and gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the
1516 link's own address, the scope will be set to
"host". Otherwise if the gateway is null (a direct route), a
1517 "link" scope will be used. For anything else, scope defaults to
"global".
</para>
1521 <term><varname>UseGateway=
</varname></term>
1523 <para>When true, the gateway will be requested from the DHCP server and added to the routing table with a
1524 metric of
1024, and a scope of
"link". When unset, the value specified with
<option>UseRoutes=
</option>
1529 <term><varname>UseTimezone=
</varname></term>
1531 <listitem><para>When true, the timezone received from the
1532 DHCP server will be set as timezone of the local
1533 system. Defaults to
<literal>no
</literal>.
</para></listitem>
1537 <term><varname>ClientIdentifier=
</varname></term>
1539 <para>The DHCPv4 client identifier to use. Takes one of
<literal>mac
</literal>,
<literal>duid
</literal> or
<literal>duid-only
</literal>.
1540 If set to
<literal>mac
</literal>, the MAC address of the link is used.
1541 If set to
<literal>duid
</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1542 If set to
<literal>duid-only
</literal>, only DUID is used, this may not be RFC compliant, but some setups may require to use this.
1543 Defaults to
<literal>duid
</literal>.
</para>
1548 <term><varname>VendorClassIdentifier=
</varname></term>
1550 <para>The vendor class identifier used to identify vendor
1551 type and configuration.
</para>
1556 <term><varname>UserClass=
</varname></term>
1558 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1559 it represents. The information contained in this option is a string that represents the user class of which
1560 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1561 service to classify clients. Takes a whitespace-separated list of strings.
</para>
1566 <term><varname>MaxAttempts=
</varname></term>
1568 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1569 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>.
1570 Note that the time between retries is increased exponentially, so the network will not be
1571 overloaded even if this number is high.
</para>
1576 <term><varname>DUIDType=
</varname></term>
1578 <para>Override the global
<varname>DUIDType
</varname> setting for this network. See
1579 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1580 for a description of possible values.
</para>
1585 <term><varname>DUIDRawData=
</varname></term>
1587 <para>Override the global
<varname>DUIDRawData
</varname> setting for this network. See
1588 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1589 for a description of possible values.
</para>
1594 <term><varname>IAID=
</varname></term>
1596 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned integer.
</para>
1601 <term><varname>RequestBroadcast=
</varname></term>
1603 <para>Request the server to use broadcast messages before
1604 the IP address has been configured. This is necessary for
1605 devices that cannot receive RAW packets, or that cannot
1606 receive packets at all before an IP address has been
1607 configured. On the other hand, this must not be enabled on
1608 networks where broadcasts are filtered out.
</para>
1613 <term><varname>RouteMetric=
</varname></term>
1615 <para>Set the routing metric for routes specified by the
1621 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1623 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1624 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1626 <para>When used in combination with
<varname>VRF=
</varname> the
1627 VRF's routing table is used unless this parameter is specified.
1633 <term><varname>RouteMTUBytes=
</varname></term>
1635 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.
</para>
1640 <term><varname>ListenPort=
</varname></term>
1642 <para>Allow setting custom port for the DHCP client to listen on.
</para>
1647 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
1649 <para>Allows to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease lifetime.
1650 Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal> means that the address
1651 never expires. Defaults to unset.
</para>
1656 <term><varname>SendRelease=
</varname></term>
1658 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops.
1659 Defaults to true.
</para>
1664 <term><varname>SendDecline=
</varname></term>
1666 <para>A boolean. When
<literal>true
</literal>, DHCPv4 clients receives IP address from DHCP server.
1667 After new IP is received, DHCPv4 performs IPv4 Duplicate Address Detection. If duplicate use of IP is detected
1668 the DHCPv4 client rejects the IP by sending a DHCPDECLINE packet DHCP clients try to obtain an IP address again.
1669 See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
1670 Defaults to
<literal>unset
</literal>.
</para>
1675 <term><varname>BlackList=
</varname></term>
1677 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are rejected.
</para>
1682 <term><varname>RequestOptions=
</varname></term>
1684 <para>When configured, allows to set arbitrary request options in the DHCPv4 request options list and will be
1685 sent to the DHCPV4 server. A whitespace-separated list of integers in the range
1.
.254. Defaults to unset.
</para>
1690 <term><varname>SendOption=
</varname></term>
1692 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data type
1693 and data separated with a colon
1694 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1695 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1696 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1697 <literal>string
</literal>. Special characters in the data string may be escaped using
1698 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1699 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1700 then all options specified earlier are cleared. Defaults to unset.
</para>
1705 <term><varname>SendVendorOption=
</varname></term>
1707 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data type
1708 and data separated with a colon
1709 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1710 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1711 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1712 <literal>string
</literal>. Special characters in the data string may be escaped using
1713 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1714 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1715 then all options specified earlier are cleared. Defaults to unset.
</para>
1722 <title>[DHCPv6] Section Options
</title>
1723 <para>The
<literal>[DHCPv6]
</literal> section configures the DHCPv6 client, if it is enabled with the
1724 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
</para>
1726 <variablelist class='network-directives'
>
1728 <term><varname>UseDNS=
</varname></term>
1729 <term><varname>UseNTP=
</varname></term>
1731 <para>As in the
<literal>[DHCPv4]
</literal> section.
</para>
1736 <term><varname>RapidCommit=
</varname></term>
1738 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1739 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1740 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1741 four-method exchange (solicit, advertise, request, and reply). The two-message exchange provides
1742 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1743 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
1744 Defaults to true.
</para>
1749 <term><varname>MUDURL=
</varname></term>
1751 <para>When configured, the Manufacturer Usage Descriptions (MUD) URL will be sent to the DHCPV6 server.
1752 Takes an URL of length up to
255 characters. A superficial verification that the string is a valid URL
1753 will be performed. DHCPv6 clients are intended to have at most one MUD URL associated with them. See
1754 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
1759 <term><varname>RequestOptions=
</varname></term>
1761 <para>When configured, allows to set arbitrary request options in the DHCPv6 request options list and will
1762 sent to the DHCPV6 server. A whitespace-separated list of integers in the range
1.
.254. Defaults to unset.
</para>
1767 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
1769 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
1770 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
1771 makes DHCPv6 request network information in a stateless manner using a two-message Information
1772 Request and Information Reply message exchange.
1773 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
1774 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
1775 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
1776 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
1777 By default this option is set to 'false', enable it if no prefixes are delegated when the device
1778 should be acting as a CE router.
</para>
1783 <term><varname>PrefixDelegationHint=
</varname></term>
1785 <para>Takes an IPv6 address with prefix length as
<varname>Address=
</varname> in
1786 the
"[Network]" section. Specifies the DHCPv6 client for the requesting router to include
1787 a prefix-hint in the DHCPv6 solicitation. Prefix ranges
1.
.128. Defaults to unset.
</para>
1792 <term><varname>WithoutRA=
</varname></term>
1794 <para>When true, DHCPv6 client starts without router advertisements's managed or other address configuration flag.
1795 Defaults to false.
</para>
1800 <term><varname>SendOption=
</varname></term>
1802 <para>As in the
<literal>[DHCPv4]
</literal> section, however because DHCPv6 uses
16-bit fields to store
1803 option numbers, the option number is an integer in the range
1.
.65536.
</para>
1808 <term><varname>UserClass=
</varname></term>
1810 <para>A DHCPv6 client can use User Class option to identify the type or category of user or applications
1811 it represents. The information contained in this option is a string that represents the user class of which
1812 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1813 service to classify clients. Special characters in the data string may be escaped using
1814 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1815 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1816 then all options specified earlier are cleared. Takes a whitespace-separated list of strings. Note that
1817 currently NUL bytes are not allowed.
</para>
1822 <term><varname>VendorClass=
</varname></term>
1824 <para>A DHCPv6 client can use VendorClass option to identify the vendor that
1825 manufactured the hardware on which the client is running. The information
1826 contained in the data area of this option is contained in one or more opaque
1827 fields that identify details of the hardware configuration. Takes a
1828 whitespace-separated list of strings.
</para>
1835 <title>[IPv6AcceptRA] Section Options
</title>
1836 <para>The
<literal>[IPv6AcceptRA]
</literal> section configures the IPv6 Router Advertisement
1837 (RA) client, if it is enabled with the
<varname>IPv6AcceptRA=
</varname> setting described
1840 <variablelist class='network-directives'
>
1842 <term><varname>UseDNS=
</varname></term>
1844 <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
1845 precedence over any statically configured ones.
</para>
1847 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
1848 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1853 <term><varname>UseDomains=
</varname></term>
1855 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1856 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
1857 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
1858 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
1859 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
1860 <literal>~
</literal>. Defaults to false.
</para>
1862 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1863 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
1864 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1865 single-label names.
</para>
1867 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1868 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1873 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1875 <para>The table identifier for the routes received in the Router Advertisement
1876 (a number between
1 and
4294967295, or
0 to unset).
1877 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1883 <term><varname>UseAutonomousPrefix=
</varname></term>
1885 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
1886 precedence over any statically configured ones.
</para>
1891 <term><varname>UseOnLinkPrefix=
</varname></term>
1893 <para>When true (the default), the onlink prefix received in the Router Advertisement will be used and take
1894 precedence over any statically configured ones.
</para>
1899 <term><varname>BlackList=
</varname></term>
1901 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router advertisements in the list are ignored.
</para>
1906 <term><varname>DHCPv6Client=
</varname></term>
1908 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true (the default), the DHCPv6 client will be started when the
1909 RA has the managed or other information flag. If set to
<literal>always
</literal>, the DHCPv6 client will be started even if there is no
1910 managed or other information flag in the RA.
</para>
1917 <title>[DHCPServer] Section Options
</title>
1918 <para>The
<literal>[DHCPServer]
</literal> section contains
1919 settings for the DHCP server, if enabled via the
1920 <varname>DHCPServer=
</varname> option described above:
</para>
1922 <variablelist class='network-directives'
>
1925 <term><varname>PoolOffset=
</varname></term>
1926 <term><varname>PoolSize=
</varname></term>
1928 <listitem><para>Configures the pool of addresses to hand out. The pool
1929 is a contiguous sequence of IP addresses in the subnet configured for
1930 the server address, which does not include the subnet nor the broadcast
1931 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
1932 from the start of subnet, or zero to use the default value.
1933 <varname>PoolSize=
</varname> takes the number of IP addresses in the
1934 pool or zero to use the default value. By default, the pool starts at
1935 the first address after the subnet address and takes up the rest of
1936 the subnet, excluding the broadcast address. If the pool includes
1937 the server address (the default), this is reserved and not handed
1938 out to clients.
</para></listitem>
1942 <term><varname>DefaultLeaseTimeSec=
</varname></term>
1943 <term><varname>MaxLeaseTimeSec=
</varname></term>
1945 <listitem><para>Control the default and maximum DHCP lease
1946 time to pass to clients. These settings take time values in seconds or
1947 another common time unit, depending on the suffix. The default
1948 lease time is used for clients that did not ask for a specific
1949 lease time. If a client asks for a lease time longer than the
1950 maximum lease time, it is automatically shortened to the
1951 specified time. The default lease time defaults to
1h, the
1952 maximum lease time to
12h. Shorter lease times are beneficial
1953 if the configuration data in DHCP leases changes frequently
1954 and clients shall learn the new settings with shorter
1955 latencies. Longer lease times reduce the generated DHCP
1956 network traffic.
</para></listitem>
1960 <term><varname>EmitDNS=
</varname></term>
1961 <term><varname>DNS=
</varname></term>
1963 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1964 to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
1965 The DNS servers to pass to clients may be configured with the
1966 <varname>DNS=
</varname> option, which takes a list of IPv4
1967 addresses. If the
<varname>EmitDNS=
</varname> option is
1968 enabled but no servers configured, the servers are
1969 automatically propagated from an
"uplink" interface that has
1970 appropriate servers set. The
"uplink" interface is determined
1971 by the default route of the system with the highest
1972 priority. Note that this information is acquired at the time
1973 the lease is handed out, and does not take uplink interfaces
1974 into account that acquire DNS or NTP server information at a
1975 later point. DNS server propagation does not take
1976 <filename>/etc/resolv.conf
</filename> into account. Also, note
1977 that the leases are not refreshed if the uplink network
1978 configuration changes. To ensure clients regularly acquire the
1979 most current uplink DNS server information, it is thus
1980 advisable to shorten the DHCP lease time via
1981 <varname>MaxLeaseTimeSec=
</varname> described
1982 above.
</para></listitem>
1986 <term><varname>EmitNTP=
</varname></term>
1987 <term><varname>NTP=
</varname></term>
1989 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1990 <varname>DNS=
</varname> settings described above, these
1991 settings configure whether and what NTP server information
1992 shall be emitted as part of the DHCP lease. The same syntax,
1993 propagation semantics and defaults apply as for
1994 <varname>EmitDNS=
</varname> and
1995 <varname>DNS=
</varname>.
</para></listitem>
1999 <term><varname>EmitSIP=
</varname></term>
2000 <term><varname>SIP=
</varname></term>
2002 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
2003 <varname>DNS=
</varname> settings described above, these
2004 settings configure whether and what SIP server information
2005 shall be emitted as part of the DHCP lease. The same syntax,
2006 propagation semantics and defaults apply as for
2007 <varname>EmitDNS=
</varname> and
2008 <varname>DNS=
</varname>.
</para></listitem>
2012 <term><varname>POP3Servers=
</varname></term>
2014 <listitem><para>Similar to the
<varname>DNS=
</varname> setting described above, this setting
2015 configures whether and what POP3 server information shall be emitted as part of the DHCP lease. The
2016 same syntax, propagation semantics and defaults apply as for
2017 <varname>DNS=
</varname>.
</para></listitem>
2021 <term><varname>SMTPServers=
</varname></term>
2023 <listitem><para>Similar to the
<varname>DNS=
</varname> setting described above, this
2024 setting configures whether and what SMTP server information shall be emitted as part of
2025 the DHCP lease. The same syntax, propagation semantics and defaults apply as for
2026 <varname>DNS=
</varname>.
</para></listitem>
2030 <term><varname>LPRServers=
</varname></term>
2032 <listitem><para>Similar to the
<varname>DNS=
</varname> setting described above, this
2033 setting configures whether and what LPR (line printer) server information shall be emitted
2034 as part of the DHCP lease. The same syntax, propagation semantics and defaults apply as for
2035 <varname>DNS=
</varname>.
</para></listitem>
2039 <term><varname>EmitRouter=
</varname></term>
2041 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
2042 setting described above, this setting configures whether the
2043 DHCP lease should contain the router option. The same syntax,
2044 propagation semantics and defaults apply as for
2045 <varname>EmitDNS=
</varname>.
</para></listitem>
2049 <term><varname>EmitTimezone=
</varname></term>
2050 <term><varname>Timezone=
</varname></term>
2052 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
2053 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
2054 <varname>Timezone=
</varname> setting takes a timezone string
2055 (such as
<literal>Europe/Berlin
</literal> or
2056 <literal>UTC
</literal>) to pass to clients. If no explicit
2057 timezone is set, the system timezone of the local host is
2058 propagated, as determined by the
2059 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
2063 <term><varname>SendOption=
</varname></term>
2065 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
2066 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2067 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
2068 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
2069 <literal>string
</literal>. Special characters in the data string may be escaped using
2070 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2071 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2072 then all options specified earlier are cleared. Defaults to unset.
</para>
2077 <term><varname>SendVendorOption=
</varname></term>
2079 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
2080 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2081 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
2082 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
2083 <literal>string
</literal>. Special characters in the data string may be escaped using
2084 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2085 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2086 then all options specified earlier are cleared. Defaults to unset.
</para>
2094 <title>[IPv6PrefixDelegation] Section Options
</title>
2095 <para>The
<literal>[IPv6PrefixDelegation]
</literal> section contains
2096 settings for sending IPv6 Router Advertisements and whether to act as
2097 a router, if enabled via the
<varname>IPv6PrefixDelegation=
</varname>
2098 option described above. IPv6 network prefixes are defined with one or
2099 more
<literal>[IPv6Prefix]
</literal> sections.
</para>
2101 <variablelist class='network-directives'
>
2104 <term><varname>Managed=
</varname></term>
2105 <term><varname>OtherInformation=
</varname></term>
2107 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
2108 addresses on the network link when
<varname>Managed=
</varname>
2109 is set to
<literal>true
</literal> or if only additional network
2110 information can be obtained via DHCPv6 for the network link when
2111 <varname>OtherInformation=
</varname> is set to
2112 <literal>true
</literal>. Both settings default to
2113 <literal>false
</literal>, which means that a DHCPv6 server is not being
2114 used.
</para></listitem>
2118 <term><varname>RouterLifetimeSec=
</varname></term>
2120 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. If set,
2121 this host also announces itself in Router Advertisements as an IPv6
2122 router for the network link. When unset, the host is not acting as a router.
</para>
2127 <term><varname>RouterPreference=
</varname></term>
2129 <listitem><para>Configures IPv6 router preference if
2130 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
2131 <literal>high
</literal>,
<literal>medium
</literal> and
2132 <literal>low
</literal>, with
<literal>normal
</literal> and
2133 <literal>default
</literal> added as synonyms for
2134 <literal>medium
</literal> just to make configuration easier. See
2135 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2136 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
2140 <term><varname>EmitDNS=
</varname></term>
2141 <term><varname>DNS=
</varname></term>
2143 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
2144 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is
2145 true.
<varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that
2146 case the IPv6 link local address is distributed. If
<varname>DNS=
</varname> is empty, DNS
2147 servers are read from the
<literal>[Network]
</literal> section. If the
2148 <literal>[Network]
</literal> section does not contain any DNS servers either, DNS servers from
2149 the uplink with the highest priority default route are used. When
<varname>EmitDNS=
</varname>
2150 is false, no DNS server information is sent in Router Advertisement messages.
2151 <varname>EmitDNS=
</varname> defaults to true.
2156 <term><varname>EmitDomains=
</varname></term>
2157 <term><varname>Domains=
</varname></term>
2159 <listitem><para>A list of DNS search domains distributed via Router
2160 Advertisement messages when
<varname>EmitDomains=
</varname> is true. If
2161 <varname>Domains=
</varname> is empty, DNS search domains are read from the
2162 <literal>[Network]
</literal> section. If the
<literal>[Network]
</literal>
2163 section does not contain any DNS search domains either, DNS search
2164 domains from the uplink with the highest priority default route are
2165 used. When
<varname>EmitDomains=
</varname> is false, no DNS search domain
2166 information is sent in Router Advertisement messages.
2167 <varname>EmitDomains=
</varname> defaults to true.
2172 <term><varname>DNSLifetimeSec=
</varname></term>
2174 <listitem><para>Lifetime in seconds for the DNS server addresses listed
2175 in
<varname>DNS=
</varname> and search domains listed in
2176 <varname>Domains=
</varname>.
</para></listitem>
2183 <title>[IPv6Prefix] Section Options
</title>
2184 <para>One or more
<literal>[IPv6Prefix]
</literal> sections contain the IPv6
2185 prefixes that are announced via Router Advertisements. See
2186 <ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink>
2187 for further details.
</para>
2189 <variablelist class='network-directives'
>
2192 <term><varname>AddressAutoconfiguration=
</varname></term>
2193 <term><varname>OnLink=
</varname></term>
2195 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
2196 autoconfigured with this prefix and whether the prefix can be used for
2197 onlink determination. Both settings default to
<literal>true
</literal>
2198 in order to ease configuration.
2203 <term><varname>Prefix=
</varname></term>
2205 <listitem><para>The IPv6 prefix that is to be distributed to hosts.
2206 Similarly to configuring static IPv6 addresses, the setting is
2207 configured as an IPv6 prefix and its prefix length, separated by a
2208 <literal>/
</literal> character. Use multiple
2209 <literal>[IPv6Prefix]
</literal> sections to configure multiple IPv6
2210 prefixes since prefix lifetimes, address autoconfiguration and onlink
2211 status may differ from one prefix to another.
</para></listitem>
2215 <term><varname>PreferredLifetimeSec=
</varname></term>
2216 <term><varname>ValidLifetimeSec=
</varname></term>
2218 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2219 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
2220 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
2221 to
2592000 seconds (
30 days).
</para></listitem>
2225 <term><varname>Assign=
</varname></term>
2226 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
2233 <title>[IPv6RoutePrefix] Section Options
</title>
2234 <para>One or more
<literal>[IPv6RoutePrefix]
</literal> sections contain the IPv6
2235 prefix routes that are announced via Router Advertisements. See
2236 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2237 for further details.
</para>
2239 <variablelist class='network-directives'
>
2242 <term><varname>Route=
</varname></term>
2244 <listitem><para>The IPv6 route that is to be distributed to hosts.
2245 Similarly to configuring static IPv6 routes, the setting is
2246 configured as an IPv6 prefix routes and its prefix route length,
2247 separated by a
<literal>/
</literal> character. Use multiple
2248 <literal>[IPv6PrefixRoutes]
</literal> sections to configure multiple IPv6
2249 prefix routes.
</para></listitem>
2253 <term><varname>LifetimeSec=
</varname></term>
2255 <listitem><para>Lifetime for the route prefix measured in
2256 seconds.
<varname>LifetimeSec=
</varname> defaults to
604800 seconds (one week).
2264 <title>[Bridge] Section Options
</title>
2265 <para>The
<literal>[Bridge]
</literal> section accepts the
2266 following keys.
</para>
2267 <variablelist class='network-directives'
>
2269 <term><varname>UnicastFlood=
</varname></term>
2271 <para>Takes a boolean. Controls whether the bridge should flood
2272 traffic for which an FDB entry is missing and the destination
2273 is unknown through this port. When unset, the kernel's default will be used.
2278 <term><varname>MulticastFlood=
</varname></term>
2280 <para>Takes a boolean. Controls whether the bridge should flood
2281 traffic for which an MDB entry is missing and the destination
2282 is unknown through this port. When unset, the kernel's default will be used.
2287 <term><varname>MulticastToUnicast=
</varname></term>
2289 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2290 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2291 When unset, the kernel's default will be used.
2296 <term><varname>NeighborSuppression=
</varname></term>
2298 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2299 this port. When unset, the kernel's default will be used.
2304 <term><varname>Learning=
</varname></term>
2306 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2307 this port. When unset, the kernel's default will be used.
2312 <term><varname>HairPin=
</varname></term>
2314 <para>Takes a boolean. Configures whether traffic may be sent back
2315 out of the port on which it was received. When this flag is false, and the bridge
2316 will not forward traffic back out of the receiving port.
2317 When unset, the kernel's default will be used.
</para>
2321 <term><varname>UseBPDU=
</varname></term>
2323 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2324 processed by the bridge port. When unset, the kernel's default will be used.
</para>
2328 <term><varname>FastLeave=
</varname></term>
2330 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2331 traffic on a port that receives an IGMP Leave message. It is only used with
2332 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
2336 <term><varname>AllowPortToBeRoot=
</varname></term>
2338 <para>Takes a boolean. Configures whether a given port is allowed to
2339 become a root port. Only used when STP is enabled on the bridge.
2340 When unset, the kernel's default will be used.
</para>
2344 <term><varname>ProxyARP=
</varname></term>
2346 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2347 When unset, the kernel's default will be used.
</para>
2351 <term><varname>ProxyARPWiFi=
</varname></term>
2353 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2354 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
2355 When unset, the kernel's default will be used.
</para>
2359 <term><varname>MulticastRouter=
</varname></term>
2361 <para>Configures this port for having multicast routers attached. A port with a multicast
2362 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
2363 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
2364 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
2365 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
2366 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
2370 <term><varname>Cost=
</varname></term>
2372 <para>Sets the
"cost" of sending packets of this interface.
2373 Each port in a bridge may have a different speed and the cost
2374 is used to decide which link to use. Faster interfaces
2375 should have lower costs. It is an integer value between
1 and
2380 <term><varname>Priority=
</varname></term>
2382 <para>Sets the
"priority" of sending packets on this interface.
2383 Each port in a bridge may have a different priority which is used
2384 to decide which link to use. Lower value means higher priority.
2385 It is an integer value between
0 to
63. Networkd does not set any
2386 default, meaning the kernel default value of
32 is used.
</para>
2392 <title>[BridgeFDB] Section Options
</title>
2393 <para>The
<literal>[BridgeFDB]
</literal> section manages the
2394 forwarding database table of a port and accepts the following
2395 keys. Specify several
<literal>[BridgeFDB]
</literal> sections to
2396 configure several static MAC table entries.
</para>
2398 <variablelist class='network-directives'
>
2400 <term><varname>MACAddress=
</varname></term>
2402 <para>As in the
<literal>[Network]
</literal> section. This
2403 key is mandatory.
</para>
2407 <term><varname>Destination=
</varname></term>
2409 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
2413 <term><varname>VLANId=
</varname></term>
2415 <para>The VLAN ID for the new static MAC table entry. If
2416 omitted, no VLAN ID information is appended to the new static MAC
2421 <term><varname>VNI=
</varname></term>
2423 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2424 the remote VXLAN tunnel endpoint. Takes a number in the range
1-
16777215.
2425 Defaults to unset.
</para>
2429 <term><varname>AssociatedWith=
</varname></term>
2431 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
2432 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
2433 <literal>use
</literal> means the address is in use. User space can use this option to
2434 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
2435 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
2436 means the address is associated with master devices fdb.
<literal>router
</literal> means
2437 the destination address is associated with a router. Note that it's valid if the referenced
2438 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
2445 <title>[LLDP] Section Options
</title>
2446 <para>The
<literal>[LLDP]
</literal> section manages the Link Layer Discovery Protocol (LLDP) and accepts the
2447 following keys.
</para>
2448 <variablelist class='network-directives'
>
2450 <term><varname>MUDURL=
</varname></term>
2452 <para>Controls support for Ethernet LLDP packet's Manufacturer Usage Description (MUD). MUD is an embedded software
2453 standard defined by the IETF that allows IoT Device makers to advertise device specifications, including the intended
2454 communication patterns for their device when it connects to the network. The network can then use this intent to author
2455 a context-specific access policy, so the device functions only within those parameters. Takes an URL of length up to
255
2456 characters. A superficial verification that the string is a valid URL
2457 will be performed. See
2458 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink> for details. The MUD URL received
2459 from the LLDP packets will be saved at the state files and can be read via
2460 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
2467 <title>[CAN] Section Options
</title>
2468 <para>The
<literal>[CAN]
</literal> section manages the Controller Area Network (CAN bus) and accepts the
2469 following keys.
</para>
2470 <variablelist class='network-directives'
>
2472 <term><varname>BitRate=
</varname></term>
2474 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
2475 be used here. Takes a number in the range
1.
.4294967295.
</para>
2479 <term><varname>SamplePoint=
</varname></term>
2481 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2482 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2486 <term><varname>DataBitRate=
</varname></term>
2487 <term><varname>DataSamplePoint=
</varname></term>
2489 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
2490 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
2494 <term><varname>FDMode=
</varname></term>
2496 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
2497 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
2498 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys.
</para>
2502 <term><varname>FDNonISO=
</varname></term>
2504 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
2505 interface. When unset, the kernel's default will be used.
</para>
2509 <term><varname>RestartSec=
</varname></term>
2511 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2512 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2513 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2514 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2515 automatic restart off. By default automatic restart is disabled.
</para>
2519 <term><varname>Termination=
</varname></term>
2521 <para>Takes a boolean. When
<literal>yes
</literal>, the termination resistor will be selected for
2522 the bias network. When unset, the kernel's default will be used.
</para>
2526 <term><varname>TripleSampling=
</varname></term>
2528 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2529 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
2533 <term><varname>ListenOnly=
</varname></term>
2535 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
2536 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
2537 bit. Listen-only mode is important to debug CAN networks without interfering with the
2538 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
2546 <title>[QDisc] Section Options
</title>
2547 <para>The
<literal>[QDisc]
</literal> section manages the traffic control queueing discipline (qdisc).
</para>
2549 <variablelist class='network-directives'
>
2551 <term><varname>Parent=
</varname></term>
2553 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
2554 or
<literal>ingress
</literal>. This is mandatory.
</para>
2558 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2563 <title>[NetworkEmulator] Section Options
</title>
2564 <para>The
<literal>[NetworkEmulator]
</literal> section manages the queueing discipline (qdisc) of
2565 the network emulator. It can be used to configure the kernel packet scheduler and simulate packet
2566 delay and loss for UDP or TCP applications, or limit the bandwidth usage of a particular service to
2567 simulate internet connections.
</para>
2569 <variablelist class='network-directives'
>
2570 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2571 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2574 <term><varname>DelaySec=
</varname></term>
2576 <para>Specifies the fixed amount of delay to be added to all packets going out of the
2577 interface. Defaults to unset.
</para>
2582 <term><varname>DelayJitterSec=
</varname></term>
2584 <para>Specifies the chosen delay to be added to the packets outgoing to the network
2585 interface. Defaults to unset.
</para>
2590 <term><varname>PacketLimit=
</varname></term>
2592 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
2593 An unsigned integer ranges
0 to
4294967294. Defaults to
1000.
</para>
2598 <term><varname>LossRate=
</varname></term>
2600 <para>Specifies an independent loss probability to be added to the packets outgoing from the
2601 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2606 <term><varname>DuplicateRate=
</varname></term>
2608 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
2609 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2616 <title>[TokenBucketFilter] Section Options
</title>
2617 <para>The
<literal>[TokenBucketFilter]
</literal> section manages the queueing discipline (qdisc) of
2618 token bucket filter (tbf).
</para>
2620 <variablelist class='network-directives'
>
2621 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2622 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2625 <term><varname>LatencySec=
</varname></term>
2627 <para>Specifies the latency parameter, which specifies the maximum amount of time a
2628 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
2633 <term><varname>LimitSize=
</varname></term>
2635 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
2636 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
2637 respectively, to the base of
1000. Defaults to unset.
</para>
2642 <term><varname>Burst=
</varname></term>
2644 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
2645 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
2646 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to
2652 <term><varname>Rate=
</varname></term>
2654 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
2655 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
2656 Defaults to unset.
</para>
2661 <term><varname>MPUBytes=
</varname></term>
2663 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
2664 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2665 Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to zero.
</para>
2670 <term><varname>PeakRate=
</varname></term>
2672 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
2673 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2674 1000. Defaults to unset.
</para>
2679 <term><varname>MTUBytes=
</varname></term>
2681 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
2682 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000.
2683 Defaults to unset.
</para>
2690 <title>[PIE] Section Options
</title>
2691 <para>The
<literal>[PIE]
</literal> section manages the queueing discipline
2692 (qdisc) of Proportional Integral controller-Enhanced (PIE).
</para>
2694 <variablelist class='network-directives'
>
2695 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2696 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2699 <term><varname>PacketLimit=
</varname></term>
2701 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2702 dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2709 <title>[StochasticFairBlue] Section Options
</title>
2710 <para>The
<literal>[StochasticFairBlue]
</literal> section manages the queueing discipline
2711 (qdisc) of stochastic fair blue (sfb).
</para>
2713 <variablelist class='network-directives'
>
2714 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2715 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2718 <term><varname>PacketLimit=
</varname></term>
2720 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2721 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2728 <title>[StochasticFairnessQueueing] Section Options
</title>
2729 <para>The
<literal>[StochasticFairnessQueueing]
</literal> section manages the queueing discipline
2730 (qdisc) of stochastic fairness queueing (sfq).
</para>
2732 <variablelist class='network-directives'
>
2733 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2734 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2737 <term><varname>PerturbPeriodSec=
</varname></term>
2739 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
2746 <title>[BFIFO] Section Options
</title>
2747 <para>The
<literal>[BFIFO]
</literal> section manages the queueing discipline (qdisc) of
2748 Byte limited Packet First In First Out (bfifo).
</para>
2750 <variablelist class='network-directives'
>
2751 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2752 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2755 <term><varname>LimitSize=
</varname></term>
2757 <para>Specifies the hard limit on the FIFO size in bytes. The size limit (a buffer size) to prevent it
2758 from overflowing in case it is unable to dequeue packets as quickly as it receives them. When this limit
2759 is reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed as
2760 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2767 <title>[PFIFO] Section Options
</title>
2768 <para>The
<literal>[PFIFO]
</literal> section manages the queueing discipline (qdisc) of
2769 Packet First In First Out (pfifo).
</para>
2771 <variablelist class='network-directives'
>
2772 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2773 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2776 <term><varname>PacketLimit=
</varname></term>
2778 <para>Specifies the hard limit on the FIFO size in number of packets. The size limit (a buffer size) to prevent it
2779 from overflowing in case it is unable to dequeue packets as quickly as it receives them. When this limit is reached,
2780 incoming packets are dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2787 <title>[PFIFOHeadDrop] Section Options
</title>
2788 <para>The
<literal>[PFIFOHeadDrop]
</literal> section manages the queueing discipline (qdisc) of
2789 Packet First In First Out Head Drop (pfifo_head_drop).
</para>
2791 <variablelist class='network-directives'
>
2792 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2793 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2796 <term><varname>PacketLimit=
</varname></term>
2798 <para>As in
<literal>[PFIFO]
</literal> section.
</para></listitem>
2804 <title>[PFIFOFast] Section Options
</title>
2805 <para>The
<literal>[PFIFOFast]
</literal> section manages the queueing discipline (qdisc) of
2806 Packet First In First Out Fast (pfifo_fast).
</para>
2808 <variablelist class='network-directives'
>
2809 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2810 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2815 <title>[CAKE] Section Options
</title>
2816 <para>The
<literal>[CAKE]
</literal> section manages the queueing discipline (qdisc) of
2817 Common Applications Kept Enhanced (CAKE).
</para>
2819 <variablelist class='network-directives'
>
2820 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2821 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2824 <term><varname>Overhead=
</varname></term>
2826 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative.
2827 Takes an integer ranges -
64 to
256. Defaults to unset and kernel's default is used.
</para>
2832 <term><varname>Bandwidth=
</varname></term>
2834 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
2835 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
2836 unset and kernel's default is used.
</para>
2843 <title>[ControlledDelay] Section Options
</title>
2844 <para>The
<literal>[ControlledDelay]
</literal> section manages the queueing discipline (qdisc) of
2845 controlled delay (CoDel).
</para>
2847 <variablelist class='network-directives'
>
2848 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2849 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2852 <term><varname>PacketLimit=
</varname></term>
2854 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2855 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2860 <term><varname>TargetSec=
</varname></term>
2862 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2863 Defaults to unset and kernel's default is used.
</para>
2868 <term><varname>IntervalSec=
</varname></term>
2870 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2871 become too stale. Defaults to unset and kernel's default is used.
</para>
2876 <term><varname>ECN=
</varname></term>
2878 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2879 unset and kernel's default is used.
</para>
2884 <term><varname>CEThresholdSec=
</varname></term>
2886 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2887 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2894 <title>[DeficitRoundRobinScheduler] Section Options
</title>
2895 <para>The
<literal>[DeficitRoundRobinScheduler]
</literal> section manages the queueing discipline (qdisc) of
2896 Deficit Round Robin Scheduler (DRR).
</para>
2898 <variablelist class='network-directives'
>
2899 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2900 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2905 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
2906 <para>The
<literal>[DeficitRoundRobinSchedulerClass]
</literal> section manages the traffic control class of
2907 Deficit Round Robin Scheduler (DRR).
</para>
2909 <variablelist class='network-directives'
>
2910 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
2911 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
2914 <term><varname>Quantum=
</varname></term>
2916 <para>Specifies the amount of bytes a flow is allowed to dequeue before the
2917 scheduler moves to the next class. An unsigned integer ranges
1 to
4294967294.
2918 Defaults to the MTU of the interface.
</para>
2926 <title>[GenericRandomEarlyDetection] Section Options
</title>
2927 <para>The
<literal>[GenericRandomEarlyDetection]
</literal> section manages the queueing discipline
2928 (qdisc) of Generic Random Early Detection (GRED).
</para>
2930 <variablelist class='network-directives'
>
2931 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2932 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2935 <term><varname>VirtualQueues=
</varname></term>
2937 <para>Specifies the number of virtual queues. Takes a integer in the range
1-
16. Defaults to unset and kernel's default is used.
</para>
2942 <term><varname>DefaultVirtualQueue=
</varname></term>
2944 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
2945 Defaults to unset and kernel's default is used.
</para>
2950 <term><varname>GenericRIO=
</varname></term>
2952 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
2953 unset and kernel's default is used.
</para>
2960 <title>[FairQueueingControlledDelay] Section Options
</title>
2961 <para>The
<literal>[FairQueueingControlledDelay]
</literal> section manages the queueing discipline
2962 (qdisc) of fair queuing controlled delay (FQ-CoDel).
</para>
2964 <variablelist class='network-directives'
>
2965 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2966 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2969 <term><varname>PacketLimit=
</varname></term>
2971 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2972 dropped. Defaults to unset and kernel's default is used.
</para>
2977 <term><varname>MemoryLimit=
</varname></term>
2979 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
2980 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2981 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2986 <term><varname>Flows=
</varname></term>
2988 <para>Specifies the number of flows into which the incoming packets are classified.
2989 Defaults to unset and kernel's default is used.
</para>
2994 <term><varname>TargetSec=
</varname></term>
2996 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2997 Defaults to unset and kernel's default is used.
</para>
3002 <term><varname>IntervalSec=
</varname></term>
3004 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
3005 become too stale. Defaults to unset and kernel's default is used.
</para>
3010 <term><varname>Quantum=
</varname></term>
3012 <para>Specifies the number of bytes used as 'deficit' in the fair queuing algorithmtimespan.
3013 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
3014 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
3019 <term><varname>ECN=
</varname></term>
3021 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3022 unset and kernel's default is used.
</para>
3027 <term><varname>CEThresholdSec=
</varname></term>
3029 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3030 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3037 <title>[FairQueueing] Section Options
</title>
3038 <para>The
<literal>[FairQueueing]
</literal> section manages the queueing discipline
3039 (qdisc) of fair queue traffic policing (FQ).
</para>
3041 <variablelist class='network-directives'
>
3042 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3043 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3046 <term><varname>PacketLimit=
</varname></term>
3048 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3049 dropped. Defaults to unset and kernel's default is used.
</para>
3054 <term><varname>FlowLimit=
</varname></term>
3056 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
3057 unset and kernel's default is used.
</para>
3062 <term><varname>Quantum=
</varname></term>
3064 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
3065 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3066 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
3067 default is used.
</para>
3072 <term><varname>InitialQuantum=
</varname></term>
3074 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
3075 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
3076 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
3077 kernel's default is used.
</para>
3082 <term><varname>MaximumRate=
</varname></term>
3084 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
3085 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
3086 1000. Defaults to unset and kernel's default is used.
</para>
3091 <term><varname>Buckets=
</varname></term>
3093 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
3094 kernel's default is used.
</para>
3099 <term><varname>OrphanMask=
</varname></term>
3101 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
3102 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
3103 kernel's default is used.
</para>
3108 <term><varname>Pacing=
</varname></term>
3110 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
3111 default is used.
</para>
3116 <term><varname>CEThresholdSec=
</varname></term>
3118 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3119 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3126 <title>[TrivialLinkEqualizer] Section Options
</title>
3127 <para>The
<literal>[TrivialLinkEqualizer]
</literal> section manages the queueing discipline (qdisc) of
3128 trivial link equalizer (teql).
</para>
3130 <variablelist class='network-directives'
>
3131 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3132 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3135 <term><varname>Id=
</varname></term>
3137 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
3138 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
3139 <constant>max_equalizers=N+
1</constant> option must be loaded before
3140 <command>systemd-networkd
</command> is started.
</para>
3147 <title>[HierarchyTokenBucket] Section Options
</title>
3148 <para>The
<literal>[HierarchyTokenBucket]
</literal> section manages the queueing discipline (qdisc) of
3149 hierarchy token bucket (htb).
</para>
3151 <variablelist class='network-directives'
>
3152 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3153 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3156 <term><varname>DefaultClass=
</varname></term>
3158 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
3159 to the class. Defaults to unset.
</para>
3166 <title>[HierarchyTokenBucketClass] Section Options
</title>
3167 <para>The
<literal>[HierarchyTokenBucketClass]
</literal> section manages the traffic control class of
3168 hierarchy token bucket (htb).
</para>
3170 <variablelist class='network-directives'
>
3171 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3172 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3175 <term><varname>Priority=
</varname></term>
3177 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
3178 priority field are tried for packets first. This setting is mandatory.
</para>
3183 <term><varname>Rate=
</varname></term>
3185 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
3186 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
3187 to the base of
1000. This setting is mandatory.
</para>
3192 <term><varname>CeilRate=
</varname></term>
3194 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
3195 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
3196 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
3204 <title>[HeavyHitterFilter] Section Options
</title>
3205 <para>The
<literal>[HeavyHitterFilter]
</literal> section manages the queueing discipline
3206 (qdisc) of Heavy Hitter Filter (hhf).
</para>
3208 <variablelist class='network-directives'
>
3209 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3210 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3213 <term><varname>PacketLimit=
</varname></term>
3215 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
3216 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
3223 <title>[BridgeVLAN] Section Options
</title>
3224 <para>The
<literal>[BridgeVLAN]
</literal> section manages the VLAN ID configuration of a bridge port and accepts
3225 the following keys. Specify several
<literal>[BridgeVLAN]
</literal> sections to configure several VLAN entries.
3226 The
<varname>VLANFiltering=
</varname> option has to be enabled, see
<literal>[Bridge]
</literal> section in
3227 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3229 <variablelist class='network-directives'
>
3231 <term><varname>VLAN=
</varname></term>
3233 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
3234 from
1 to
4094.
</para>
3238 <term><varname>EgressUntagged=
</varname></term>
3240 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
3241 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
3242 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
3246 <term><varname>PVID=
</varname></term>
3248 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
3249 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
3250 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
3257 <title>Examples
</title>
3259 <title>Static network configuration
</title>
3261 <programlisting># /etc/systemd/network/
50-static.network
3266 Address=
192.168.0.15/
24
3267 Gateway=
192.168.0.1</programlisting>
3269 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
3270 specified gateway will be used for a default route.
</para>
3274 <title>DHCP on ethernet links
</title>
3276 <programlisting># /etc/systemd/network/
80-dhcp.network
3281 DHCP=yes
</programlisting>
3283 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
3284 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
3288 <title>IPv6 Prefix Delegation
</title>
3290 <programlisting># /etc/systemd/network/
55-ipv6-pd-upstream.network
3295 DHCP=ipv6
</programlisting>
3297 <programlisting># /etc/systemd/network/
56-ipv6-pd-downstream.network
3302 IPv6PrefixDelegation=dhcpv6
</programlisting>
3304 <para>This will enable IPv6 PD on the interface enp1s0 as an upstream interface where the
3305 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
</para>
3309 <title>A bridge with two enslaved links
</title>
3311 <programlisting># /etc/systemd/network/
25-bridge-static.network
3316 Address=
192.168.0.15/
24
3318 DNS=
192.168.0.1</programlisting>
3320 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
3325 Bridge=bridge0
</programlisting>
3327 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
3332 Bridge=bridge0
</programlisting>
3334 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
3335 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
3336 and network assigned, and a default route via the specified gateway will be
3337 added. The specified DNS server will be added to the global list of DNS resolvers.
3345 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
3361 EgressUntagged=
300-
400</programlisting>
3363 <para>This overrides the configuration specified in the previous example for the
3364 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
3365 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
3366 untagged when they leave on this interface. Untagged packets which arrive on this
3367 interface will be assigned VLAN ID
42.
</para>
3371 <title>Various tunnels
</title>
3373 <programlisting>/etc/systemd/network/
25-tunnels.network
3384 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
3390 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
3396 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
3402 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
3408 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
3409 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
3413 <title>A bond device
</title>
3415 <programlisting># /etc/systemd/network/
30-bond1.network
3423 <programlisting># /etc/systemd/network/
30-bond1.netdev
3429 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
3431 MACAddress=
52:
54:
00:e9:
64:
41
3437 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
3439 MACAddress=
52:
54:
00:e9:
64:
42
3445 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
3446 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
3447 will be used to acquire an address.
</para>
3451 <title>Virtual Routing and Forwarding (VRF)
</title>
3452 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
3453 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
3454 within the routing table defined during VRF creation. For kernels before
4.8 traffic
3455 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
3457 <programlisting># /etc/systemd/network/
25-vrf.network
3467 <title>MacVTap
</title>
3468 <para>This brings up a network interface
<literal>macvtap-test
</literal>
3469 and attaches it to
<literal>enp0s25
</literal>.
</para>
3470 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
3475 MACVTAP=macvtap-test
3480 <title>A Xfrm interface with physical underlying device.
</title>
3482 <programlisting># /etc/systemd/network/
27-xfrm.netdev
3487 InterfaceId=
7</programlisting>
3489 <programlisting># /etc/systemd/network/
27-eth0.network
3494 Xfrm=xfrm0
</programlisting>
3496 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
3497 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
3498 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
3504 <title>See Also
</title>
3506 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
3507 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
3508 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3509 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3510 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
projects / thirdparty / systemd.git / blob