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>Unmanaged=
</varname></term>
199 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are
200 made to bring up or configure matching links, equivalent to
201 when there are no matching network files. Defaults to
202 <literal>no
</literal>.
</para>
203 <para>This is useful for preventing later matching network
204 files from interfering with certain interfaces that are fully
205 controlled by other applications.
</para>
209 <term><varname>Group=
</varname></term>
211 <para>Link groups are similar to port ranges found in managed switches.
212 When network interfaces are added to a numbered group, operations on
213 all the interfaces from that group can be performed at once. An unsigned
214 integer ranges
0 to
4294967294. Default to unset.
</para>
218 <term><varname>RequiredForOnline=
</varname></term>
220 <para>Takes a boolean or a minimum operational state and an optional maximum operational state.
221 Please see
<citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
222 for possible operational states. When
<literal>yes
</literal>, the network is deemed required when
223 determining whether the system is online when running
224 <command>systemd-networkd-wait-online
</command>. When
<literal>no
</literal>, the network is ignored
225 when checking for online state. When a minimum operational state and an optional maximum operational
226 state are set,
<literal>yes
</literal> is implied, and this controls the minimum and maximum
227 operational state required for the network interface to be considered online.
228 Defaults to
<literal>yes
</literal>.
</para>
230 <para>The network will be brought up normally in all cases, but in
231 the event that there is no address being assigned by DHCP or the
232 cable is not plugged in, the link will simply remain offline and be
233 skipped automatically by
<command>systemd-networkd-wait-online
</command>
234 if
<literal>RequiredForOnline=no
</literal>.
</para>
241 <title>[Network] Section Options
</title>
243 <para>The
<literal>[Network]
</literal> section accepts the following keys:
</para>
245 <variablelist class='network-directives'
>
247 <term><varname>Description=
</varname></term>
249 <para>A description of the device. This is only used for
250 presentation purposes.
</para>
254 <term><varname>DHCP=
</varname></term>
256 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
257 <literal>yes
</literal>,
<literal>no
</literal>,
258 <literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults
259 to
<literal>no
</literal>.
</para>
261 <para>Note that DHCPv6 will by default be triggered by Router
262 Advertisement, if that is enabled, regardless of this parameter.
263 By enabling DHCPv6 support explicitly, the DHCPv6 client will
264 be started regardless of the presence of routers on the link,
265 or what flags the routers pass. See
266 <literal>IPv6AcceptRA=
</literal>.
</para>
268 <para>Furthermore, note that by default the domain name
269 specified through DHCP is not used for name resolution.
270 See option
<option>UseDomains=
</option> below.
</para>
272 <para>See the
<literal>[DHCPv4]
</literal> or
<literal>[DHCPv6]
</literal> section below for
273 further configuration options for the DHCP client support.
</para>
277 <term><varname>DHCPServer=
</varname></term>
279 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started. Defaults
280 to
<literal>no
</literal>. Further settings for the DHCP
281 server may be set in the
<literal>[DHCPServer]
</literal>
282 section described below.
</para>
286 <term><varname>LinkLocalAddressing=
</varname></term>
288 <para>Enables link-local address autoconfiguration. Accepts
<literal>yes
</literal>,
289 <literal>no
</literal>,
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
290 <literal>fallback
</literal>, or
<literal>ipv4-fallback
</literal>. If
291 <literal>fallback
</literal> or
<literal>ipv4-fallback
</literal> is specified, then an IPv4
292 link-local address is configured only when DHCPv4 fails. If
<literal>fallback
</literal>,
293 an IPv6 link-local address is always configured, and if
<literal>ipv4-fallback
</literal>,
294 the address is not configured. Note that, the fallback mechanism works only when DHCPv4
295 client is enabled, that is, it requires
<literal>DHCP=yes
</literal> or
296 <literal>DHCP=ipv4
</literal>. If
<varname>Bridge=
</varname> is set, defaults to
297 <literal>no
</literal>, and if not, defaults to
<literal>ipv6
</literal>.
302 <term><varname>IPv4LLRoute=
</varname></term>
304 <para>Takes a boolean. If set to true, sets up the route needed for
305 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
311 <term><varname>DefaultRouteOnDevice=
</varname></term>
313 <para>Takes a boolean. If set to true, sets up the default route bound to the interface.
314 Defaults to false. This is useful when creating routes on point-to-point interfaces.
315 This is equivalent to e.g. the following.
316 <programlisting>ip route add default dev veth99
</programlisting></para>
320 <term><varname>IPv6Token=
</varname></term>
322 <para>Specifies an optional address generation mode and a required IPv6 address. If
323 the mode is present, the two parts must be separated with a colon
324 <literal><replaceable>mode
</replaceable>:
<replaceable>address
</replaceable></literal>. The
325 address generation mode may be either
<constant>prefixstable
</constant> or
326 <constant>static
</constant>. If not specified,
<constant>static
</constant> is assumed.
328 <para>When the mode is set to
<constant>static
</constant>, or unspecified, the lower bits of
329 the supplied address are combined with the upper bits of a prefix received in a Router Advertisement
330 message to form a complete address. Note that if multiple prefixes are received in an RA message, or in
331 multiple RA messages, addresses will be formed from each of them using the supplied address. This
332 mode implements SLAAC but uses a static interface identifier instead of an identifier generated
333 using the EUI-
64 algorithm. Because the interface identifier is static, if Duplicate Address Detection
334 detects that the computed address is a duplicate (in use by another node on the link), then this
335 mode will fail to provide an address for that prefix.
337 <para>When the mode is set to
<literal>prefixstable
</literal> the RFC
7217 algorithm for generating
338 interface identifiers will be used, but only when a prefix received in an RA message matches the supplied address.
339 See
<ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink>. Prefix matching will be attempted
340 against each
<constant>prefixstable
</constant> IPv6Token variable provided in the configuration; if a received
341 prefix does not match any of the provided addresses, then the EUI-
64 algorithm will be used to form
342 an interface identifier for that prefix. This mode is also SLAAC, but with a potentially stable interface
343 identifier which does not directly map to the interface's hardware address.
345 Note that the
<constant>prefixstable
</constant> algorithm includes both the interface's name and
346 MAC address in the hash used to compute the interface identifier, so if either of those are changed the resulting
347 interface identifier (and address) will change, even if the prefix received in the RA message has not changed.
349 Note that if multiple
<constant>prefixstable
</constant> IPv6Token variables are supplied with addresses that
350 match a prefix received in an RA message, only the first one will be used to generate addresses.
355 <term><varname>LLMNR=
</varname></term>
357 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
359 url=
"https://tools.ietf.org/html/rfc4795">Link-Local
360 Multicast Name Resolution
</ulink> on the link. When set to
361 <literal>resolve
</literal>, only resolution is enabled,
362 but not host registration and announcement. Defaults to
363 true. This setting is read by
364 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
368 <term><varname>MulticastDNS=
</varname></term>
370 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
372 url=
"https://tools.ietf.org/html/rfc6762">Multicast
373 DNS
</ulink> support on the link. When set to
374 <literal>resolve
</literal>, only resolution is enabled,
375 but not host or service registration and
376 announcement. Defaults to false. This setting is read by
377 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
381 <term><varname>DNSOverTLS=
</varname></term>
383 <para>Takes a boolean or
<literal>opportunistic
</literal>.
386 url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink>
388 When set to
<literal>opportunistic
</literal>, compatibility with
389 non-DNS-over-TLS servers is increased, by automatically
390 turning off DNS-over-TLS servers in this case.
391 This option defines a per-interface setting for
392 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
393 global
<varname>DNSOverTLS=
</varname> option. Defaults to
394 false. This setting is read by
395 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
399 <term><varname>DNSSEC=
</varname></term>
401 <para>Takes a boolean. or
402 <literal>allow-downgrade
</literal>. When true, enables
404 url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink>
405 DNS validation support on the link. When set to
406 <literal>allow-downgrade
</literal>, compatibility with
407 non-DNSSEC capable networks is increased, by automatically
408 turning off DNSSEC in this case. This option defines a
409 per-interface setting for
410 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
411 global
<varname>DNSSEC=
</varname> option. Defaults to
412 false. This setting is read by
413 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
417 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
418 <listitem><para>A space-separated list of DNSSEC negative
419 trust anchor domains. If specified and DNSSEC is enabled,
420 look-ups done via the interface's DNS server will be subject
421 to the list of negative trust anchors, and not require
422 authentication for the specified domains, or anything below
423 it. Use this to disable DNSSEC authentication for specific
424 private domains, that cannot be proven valid using the
425 Internet DNS hierarchy. Defaults to the empty list. This
427 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
431 <term><varname>LLDP=
</varname></term>
433 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
434 implemented on professional routers and bridges which announces which physical port a system is connected
435 to, as well as other related data. Accepts a boolean or the special value
436 <literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
437 neighbors maintained. If
<literal>routers-only
</literal> is set only LLDP data of various types of routers
438 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
439 others). If false, LLDP reception is disabled. Defaults to
<literal>routers-only
</literal>. Use
440 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
441 collected neighbor data. LLDP is only available on Ethernet links. See
<varname>EmitLLDP=
</varname> below
442 for enabling LLDP packet emission from the local system.
447 <term><varname>EmitLLDP=
</varname></term>
449 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
450 <literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
451 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
452 a short LLDP packet with information about the local system is sent out in regular intervals on the
453 link. The LLDP packet will contain information about the local hostname, the local machine ID (as stored
454 in
<citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
455 local interface name, as well as the pretty hostname of the system (as set in
456 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
457 emission is only available on Ethernet links. Note that this setting passes data suitable for
458 identification of host to the network and should thus not be enabled on untrusted networks, where such
459 identification data should not be made available. Use this option to permit other systems to identify on
460 which interfaces they are connected to this system. The three special values control propagation of the
461 LLDP packets. The
<literal>nearest-bridge
</literal> setting permits propagation only to the nearest
462 connected bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays, but
463 not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until a customer bridge
464 is reached. For details about these concepts, see
<ulink
465 url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>. Note that
466 configuring this setting to true is equivalent to
<literal>nearest-bridge
</literal>, the recommended and
467 most restricted level of propagation. See
<varname>LLDP=
</varname> above for an option to enable LLDP
473 <term><varname>BindCarrier=
</varname></term>
475 <para>A link name or a list of link names. When set, controls the behavior of the current
476 link. When all links in the list are in an operational down state, the current link is brought
477 down. When at least one link has carrier, the current interface is brought up.
482 <term><varname>Address=
</varname></term>
484 <para>A static IPv4 or IPv6 address and its prefix length,
485 separated by a
<literal>/
</literal> character. Specify
486 this key more than once to configure several addresses.
487 The format of the address must be as described in
488 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
489 This is a short-hand for an [Address] section only
490 containing an Address key (see below). This option may be
491 specified more than once.
494 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
495 (for IPv6), a new address range of the requested size is automatically allocated from a
496 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
497 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
498 all known network configuration files to avoid address range conflicts. The default system-wide
499 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.
500 This functionality is useful to manage a large number of dynamically created network interfaces
501 with the same network configuration and automatic address range assignment.
</para>
506 <term><varname>Gateway=
</varname></term>
508 <para>The gateway address, which must be in the format
510 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
511 This is a short-hand for a [Route] section only containing
512 a Gateway key. This option may be specified more than
517 <term><varname>DNS=
</varname></term>
519 <para>A DNS server address, which must be in the format
521 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
522 This option may be specified more than once. This setting is read by
523 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
527 <term><varname>Domains=
</varname></term>
529 <para>A whitespace-separated list of domains which should be resolved using the DNS servers on
530 this link. Each item in the list should be a domain name, optionally prefixed with a tilde
531 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
532 domains without the prefix are called
"search domains" and are first used as search suffixes for
533 extending single-label hostnames (hostnames containing no dots) to become fully qualified
534 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
535 specified search domains are appended to it in turn, converting it into a fully qualified domain
536 name, until one of them may be successfully resolved.
</para>
538 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for hostnames
539 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
540 the DNS servers configured for this interface. The domain routing logic is particularly useful on
541 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
543 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
544 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
545 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
546 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
547 if a link on which they are connected is available.
</para>
549 <para>This setting is read by
550 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
551 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
552 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
553 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
554 name servers limited to a specific link.
</para>
558 <term><varname>DNSDefaultRoute=
</varname></term>
560 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
561 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
562 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
563 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
564 queries not matching any link's configured domains will be routed to this link if it has no routing-only
565 domains configured.
</para>
569 <term><varname>NTP=
</varname></term>
571 <para>An NTP server address. This option may be specified more than once. This setting is read by
572 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
576 <term><varname>IPForward=
</varname></term>
577 <listitem><para>Configures IP packet forwarding for the
578 system. If enabled, incoming packets on any network
579 interface will be forwarded to any other interfaces
580 according to the routing table. Takes a boolean,
581 or the values
<literal>ipv4
</literal> or
582 <literal>ipv6
</literal>, which only enable IP packet
583 forwarding for the specified address family. This controls
584 the
<filename>net.ipv4.ip_forward
</filename> and
585 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
586 options of the network interface (see
<ulink
587 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
588 for details about sysctl options). Defaults to
589 <literal>no
</literal>.
</para>
591 <para>Note: this setting controls a global kernel option,
592 and does so one way only: if a network that has this setting
593 enabled is set up the global setting is turned on. However,
594 it is never turned off again, even after all networks with
595 this setting enabled are shut down again.
</para>
597 <para>To allow IP packet forwarding only between specific
598 network interfaces use a firewall.
</para>
602 <term><varname>IPMasquerade=
</varname></term>
603 <listitem><para>Configures IP masquerading for the network
604 interface. If enabled, packets forwarded from the network
605 interface will be appear as coming from the local host.
606 Takes a boolean argument. Implies
607 <varname>IPForward=ipv4
</varname>. Defaults to
608 <literal>no
</literal>.
</para></listitem>
611 <term><varname>IPv6PrivacyExtensions=
</varname></term>
612 <listitem><para>Configures use of stateless temporary
613 addresses that change over time (see
<ulink
614 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
615 Privacy Extensions for Stateless Address Autoconfiguration
616 in IPv6). Takes a boolean or the special values
617 <literal>prefer-public
</literal> and
618 <literal>kernel
</literal>. When true, enables the privacy
619 extensions and prefers temporary addresses over public
620 addresses. When
<literal>prefer-public
</literal>, enables the
621 privacy extensions, but prefers public addresses over
622 temporary addresses. When false, the privacy extensions
623 remain disabled. When
<literal>kernel
</literal>, the kernel's
624 default setting will be left in place. Defaults to
625 <literal>no
</literal>.
</para></listitem>
628 <term><varname>IPv6AcceptRA=
</varname></term>
629 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
630 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they may
631 trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or if no
632 routers are found on the link. The default is to disable RA reception for bridge devices or when IP
633 forwarding is enabled, and to enable it otherwise. Cannot be enabled on bond devices and when link
634 local addressing is disabled.
</para>
636 <para>Further settings for the IPv6 RA support may be configured in the
637 <literal>[IPv6AcceptRA]
</literal> section, see below.
</para>
639 <para>Also see
<ulink
640 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink> in the kernel
641 documentation regarding
<literal>accept_ra
</literal>, but note that systemd's setting of
642 <constant>1</constant> (i.e. true) corresponds to kernel's setting of
<constant>2</constant>.
</para>
644 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
645 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
646 RA protocol is used, and the kernel's own implementation remains disabled, since
647 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
648 and these are not available from the kernel if the kernel's own implementation is used.
</para>
652 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
653 <listitem><para>Configures the amount of IPv6 Duplicate
654 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
658 <term><varname>IPv6HopLimit=
</varname></term>
659 <listitem><para>Configures IPv6 Hop Limit. For each router that
660 forwards the packet, the hop limit is decremented by
1. When the
661 hop limit field reaches zero, the packet is discarded.
662 When unset, the kernel's default will be used.
666 <term><varname>IPv4ProxyARP=
</varname></term>
667 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
668 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
669 the router accepts responsibility for routing packets to the
"real" destination. (see
<ulink
670 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
671 When unset, the kernel's default will be used.
675 <term><varname>IPv6ProxyNDP=
</varname></term>
676 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
677 Protocol) is a technique for IPv6 to allow routing of addresses to a different
678 destination when peers expect them to be present on a certain physical link.
679 In this case a router answers Neighbour Advertisement messages intended for
680 another machine by offering its own MAC address as destination.
681 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
682 Advertisement messages for addresses in the IPv6 neighbor proxy table,
683 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
684 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
685 interface depending on this option.
686 When unset, the kernel's default will be used.
690 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
691 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
692 proxied. This option may be specified more than once. systemd-networkd will add the
693 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
694 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
695 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
699 <term><varname>IPv6PrefixDelegation=
</varname></term>
700 <listitem><para>Whether to enable or disable Router Advertisement sending on a link.
701 Allowed values are
<literal>static
</literal> which distributes prefixes as defined in
702 the
<literal>[IPv6PrefixDelegation]
</literal> and any
<literal>[IPv6Prefix]
</literal>
703 sections,
<literal>dhcpv6
</literal> which requests prefixes using a DHCPv6 client
704 configured for another link and any values configured in the
705 <literal>[IPv6PrefixDelegation]
</literal> section while ignoring all static prefix
706 configuration sections,
<literal>yes
</literal> which uses both static configuration
707 and DHCPv6, and
<literal>false
</literal> which turns off IPv6 prefix delegation
708 altogether. Defaults to
<literal>false
</literal>. See the
709 <literal>[IPv6PrefixDelegation]
</literal> and the
<literal>[IPv6Prefix]
</literal>
710 sections for more configuration options.
714 <term><varname>IPv6MTUBytes=
</varname></term>
715 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
716 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
720 <term><varname>Bridge=
</varname></term>
722 <para>The name of the bridge to add the link to. See
723 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
728 <term><varname>Bond=
</varname></term>
730 <para>The name of the bond to add the link to. See
731 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
736 <term><varname>VRF=
</varname></term>
738 <para>The name of the VRF to add the link to. See
739 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
744 <term><varname>VLAN=
</varname></term>
746 <para>The name of a VLAN to create on the link. See
747 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
748 This option may be specified more than once.
</para>
752 <term><varname>IPVLAN=
</varname></term>
754 <para>The name of a IPVLAN to create on the link. See
755 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
756 This option may be specified more than once.
</para>
760 <term><varname>MACVLAN=
</varname></term>
762 <para>The name of a MACVLAN to create on the link. See
763 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
764 This option may be specified more than once.
</para>
768 <term><varname>VXLAN=
</varname></term>
770 <para>The name of a VXLAN to create on the link. See
771 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
772 This option may be specified more than once.
</para>
776 <term><varname>Tunnel=
</varname></term>
778 <para>The name of a Tunnel to create on the link. See
779 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
780 This option may be specified more than once.
</para>
784 <term><varname>MACsec=
</varname></term>
786 <para>The name of a MACsec device to create on the link. See
787 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
788 This option may be specified more than once.
</para>
792 <term><varname>ActiveSlave=
</varname></term>
794 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
795 option is only valid for following modes:
796 <literal>active-backup
</literal>,
797 <literal>balance-alb
</literal> and
798 <literal>balance-tlb
</literal>. Defaults to false.
803 <term><varname>PrimarySlave=
</varname></term>
805 <para>Takes a boolean. Specifies which slave is the primary device. The specified
806 device will always be the active slave while it is available. Only when the
807 primary is off-line will alternate devices be used. This is useful when
808 one slave is preferred over another, e.g. when one slave has higher throughput
809 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
811 <literal>active-backup
</literal>,
812 <literal>balance-alb
</literal> and
813 <literal>balance-tlb
</literal>. Defaults to false.
818 <term><varname>ConfigureWithoutCarrier=
</varname></term>
820 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
826 <term><varname>IgnoreCarrierLoss=
</varname></term>
828 <para>A boolean. Allows networkd to retain both the static and dynamic configuration of the
829 interface even if its carrier is lost. Defaults to false.
834 <term><varname>Xfrm=
</varname></term>
836 <para>The name of the xfrm to create on the link. See
837 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
838 This option may be specified more than once.
</para>
842 <term><varname>KeepConfiguration=
</varname></term>
844 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
845 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
846 will not drop static addresses and routes on starting up process. When set to
847 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
848 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
849 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
850 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
851 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
852 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
853 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
<literal>no
</literal>.
863 <title>[Address] Section Options
</title>
865 <para>An
<literal>[Address]
</literal> section accepts the
866 following keys. Specify several
<literal>[Address]
</literal>
867 sections to configure several addresses.
</para>
869 <variablelist class='network-directives'
>
871 <term><varname>Address=
</varname></term>
873 <para>As in the
<literal>[Network]
</literal> section. This key is mandatory. Each
874 <literal>[Address]
</literal> section can contain one
<varname>Address=
</varname> setting.
</para>
878 <term><varname>Peer=
</varname></term>
880 <para>The peer address in a point-to-point connection.
881 Accepts the same format as the
<varname>Address=
</varname>
886 <term><varname>Broadcast=
</varname></term>
888 <para>The broadcast address, which must be in the format
890 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
891 This key only applies to IPv4 addresses. If it is not
892 given, it is derived from the
<varname>Address=
</varname>
897 <term><varname>Label=
</varname></term>
899 <para>An address label.
</para>
903 <term><varname>PreferredLifetime=
</varname></term>
905 <para>Allows the default
"preferred lifetime" of the address to be overridden.
906 Only three settings are accepted:
<literal>forever
</literal> or
<literal>infinity
</literal>
907 which is the default and means that the address never expires, and
<literal>0</literal> which means
908 that the address is considered immediately
"expired" and will not be used,
909 unless explicitly requested. A setting of PreferredLifetime=
0 is useful for
910 addresses which are added to be used only by a specific application,
911 which is then configured to use them explicitly.
</para>
915 <term><varname>Scope=
</varname></term>
917 <para>The scope of the address, which can be
<literal>global
</literal>,
918 <literal>link
</literal> or
<literal>host
</literal> or an unsigned integer ranges
0 to
255.
919 Defaults to
<literal>global
</literal>.
</para>
923 <term><varname>HomeAddress=
</varname></term>
925 <para>Takes a boolean. Designates this address the
"home address" as defined in
926 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
927 Supported only on IPv6. Defaults to false.
</para>
931 <term><varname>DuplicateAddressDetection=
</varname></term>
933 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
934 <literal>both
</literal>,
<literal>none
</literal>. When
<literal>ipv4
</literal>,
935 performs IPv4 Duplicate Address Detection. See
936 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
937 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
938 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>.
939 Defaults to
<literal>ipv6
</literal>.
</para>
943 <term><varname>ManageTemporaryAddress=
</varname></term>
945 <para>Takes a boolean. If true the kernel manage temporary addresses created
946 from this one as template on behalf of Privacy Extensions
947 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
948 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
949 The given address needs to have a prefix length of
64. This flag allows using privacy
950 extensions in a manually configured network, just like if stateless auto-configuration
951 was active. Defaults to false.
</para>
955 <term><varname>AddPrefixRoute=
</varname></term>
957 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
958 Defaults to true.
</para>
962 <term><varname>AutoJoin=
</varname></term>
964 <para>Takes a boolean. Joining multicast group on ethernet level via
965 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
966 IGMP snooping since the switch would not replicate multicast packets on ports that did not
967 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
968 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
969 that enables then to do the required join. By extending ip address command with option
970 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
971 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
972 Defaults to
<literal>no
</literal>.
</para>
979 <title>[Neighbor] Section Options
</title>
980 <para>A
<literal>[Neighbor]
</literal> section accepts the
981 following keys. The neighbor section adds a permanent, static
982 entry to the neighbor table (IPv6) or ARP table (IPv4) for
983 the given hardware address on the links matched for the network.
984 Specify several
<literal>[Neighbor]
</literal> sections to configure
985 several static neighbors.
</para>
987 <variablelist class='network-directives'
>
989 <term><varname>Address=
</varname></term>
991 <para>The IP address of the neighbor.
</para>
995 <term><varname>LinkLayerAddress=
</varname></term>
997 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
1004 <title>[IPv6AddressLabel] Section Options
</title>
1006 <para>An
<literal>[IPv6AddressLabel]
</literal> section accepts the
1007 following keys. Specify several
<literal>[IPv6AddressLabel]
</literal>
1008 sections to configure several address labels. IPv6 address labels are
1009 used for address selection. See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>.
1010 Precedence is managed by userspace, and only the label itself is stored in the kernel
</para>
1012 <variablelist class='network-directives'
>
1014 <term><varname>Label=
</varname></term>
1016 <para> The label for the prefix (an unsigned integer) ranges
0 to
4294967294.
1017 0xffffffff is reserved. This key is mandatory.
</para>
1021 <term><varname>Prefix=
</varname></term>
1023 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
1024 This key is mandatory.
</para>
1031 <title>[RoutingPolicyRule] Section Options
</title>
1033 <para>An
<literal>[RoutingPolicyRule]
</literal> section accepts the
1034 following keys. Specify several
<literal>[RoutingPolicyRule]
</literal>
1035 sections to configure several rules.
</para>
1037 <variablelist class='network-directives'
>
1039 <term><varname>TypeOfService=
</varname></term>
1041 <para>Specifies the type of service to match a number between
0 to
255.
</para>
1045 <term><varname>From=
</varname></term>
1047 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1051 <term><varname>To=
</varname></term>
1053 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1057 <term><varname>FirewallMark=
</varname></term>
1059 <para>Specifies the iptables firewall mark value to match (a number between
1 and
4294967295).
</para>
1063 <term><varname>Table=
</varname></term>
1065 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes
1066 one of
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
1067 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1071 <term><varname>Priority=
</varname></term>
1073 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1074 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1078 <term><varname>IncomingInterface=
</varname></term>
1080 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1084 <term><varname>OutgoingInterface=
</varname></term>
1086 <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>
1090 <term><varname>SourcePort=
</varname></term>
1092 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1093 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1097 <term><varname>DestinationPort=
</varname></term>
1099 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1100 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1104 <term><varname>IPProtocol=
</varname></term>
1106 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1107 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1108 <literal>17</literal> for
<literal>udp
</literal>.
1109 Defaults to unset.
</para>
1113 <term><varname>InvertRule=
</varname></term>
1115 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1119 <term><varname>Family=
</varname></term>
1121 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1122 <literal>both
</literal>. By default, the address family is determined by the address
1123 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1124 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1125 <literal>ipv4
</literal>.
</para>
1129 <term><varname>User=
</varname></term>
1131 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1136 <term><varname>SuppressPrefixLength=
</varname></term>
1138 <para>Takes a number
<replaceable>N
</replaceable> in the range
0-
128 and rejects routing
1139 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1147 <title>[NextHop] Section Options
</title>
1148 <para>The
<literal>[NextHop]
</literal> section accepts the
1149 following keys. Specify several
<literal>[NextHop]
</literal>
1150 sections to configure several nexthop. Nexthop is used to manipulate entries in the kernel's nexthop
1153 <variablelist class='network-directives'
>
1155 <term><varname>Gateway=
</varname></term>
1157 <para>As in the
<literal>[Network]
</literal> section. This is mandatory.
</para>
1161 <term><varname>Id=
</varname></term>
1163 <para>The id of the nexthop (an unsigned integer). If unspecified or '
0' then automatically chosen by kernel.
</para>
1170 <title>[Route] Section Options
</title>
1171 <para>The
<literal>[Route]
</literal> section accepts the
1172 following keys. Specify several
<literal>[Route]
</literal>
1173 sections to configure several routes.
</para>
1175 <variablelist class='network-directives'
>
1177 <term><varname>Gateway=
</varname></term>
1179 <para>Takes the gateway address or special value
<literal>_dhcp
</literal>. If
1180 <literal>_dhcp
</literal>, then the gateway address provided by DHCP (or in the IPv6 case,
1181 provided by IPv6 RA) is used.
</para>
1185 <term><varname>GatewayOnLink=
</varname></term>
1187 <para>Takes a boolean. If set to true, the kernel does not have
1188 to check if the gateway is reachable directly by the current machine (i.e., the kernel does
1189 not need to check if the gateway is attached to the local network), so that we can insert the
1190 route in the kernel table without it being complained about. Defaults to
<literal>no
</literal>.
1195 <term><varname>Destination=
</varname></term>
1197 <para>The destination prefix of the route. Possibly
1198 followed by a slash and the prefix length. If omitted, a
1199 full-length host route is assumed.
</para>
1203 <term><varname>Source=
</varname></term>
1205 <para>The source prefix of the route. Possibly followed by
1206 a slash and the prefix length. If omitted, a full-length
1207 host route is assumed.
</para>
1211 <term><varname>Metric=
</varname></term>
1213 <para>The metric of the route (an unsigned integer).
</para>
1217 <term><varname>IPv6Preference=
</varname></term>
1219 <para>Specifies the route preference as defined in
<ulink
1220 url=
"https://tools.ietf.org/html/rfc4191">RFC4191
</ulink> for Router Discovery messages.
1221 Which can be one of
<literal>low
</literal> the route has a lowest priority,
1222 <literal>medium
</literal> the route has a default priority or
1223 <literal>high
</literal> the route has a highest priority.
</para>
1227 <term><varname>Scope=
</varname></term>
1229 <para>The scope of the route, which can be
<literal>global
</literal>,
<literal>site
</literal>,
1230 <literal>link
</literal>,
<literal>host
</literal>, or
<literal>nowhere
</literal>. For IPv4 route,
1231 defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
<literal>local
</literal>
1232 or
<literal>nat
</literal>, and
<literal>link
</literal> if
<varname>Type=
</varname> is
1233 <literal>broadcast
</literal>,
<literal>multicast
</literal>, or
<literal>anycast
</literal>.
1234 In other cases, defaults to
<literal>global
</literal>.
</para>
1238 <term><varname>PreferredSource=
</varname></term>
1240 <para>The preferred source address of the route. The address
1241 must be in the format described in
1242 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1246 <term><varname>Table=
</varname></term>
1248 <para>The table identifier for the route. Takes
<literal>default
</literal>,
1249 <literal>main
</literal>,
<literal>local
</literal> or a number between
1 and
4294967295.
1250 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1251 If unset and
<varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1252 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1253 In other cases, defaults to
<literal>main
</literal>.
1258 <term><varname>Protocol=
</varname></term>
1260 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1261 <literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1262 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1267 <term><varname>Type=
</varname></term>
1269 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1270 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1271 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1272 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1273 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1274 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1275 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1276 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1277 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1278 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1279 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1284 <term><varname>InitialCongestionWindow=
</varname></term>
1286 <para>The TCP initial congestion window is used during the start of a TCP connection. During the start of a TCP
1287 session, when a client requests a resource, the server's initial congestion window determines how many data bytes
1288 will be sent during the initial burst of data. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual
1289 suffixes K, M, G are supported and are understood to the base of
1024. When unset, the kernel's default will be used.
1294 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1296 <para>The TCP initial advertised receive window is the amount of receive data (in bytes) that can initially be buffered at one time
1297 on a connection. The sending host can send only that amount of data before waiting for an acknowledgment and window update
1298 from the receiving host. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual suffixes K, M, G are supported
1299 and are understood to the base of
1024. When unset, the kernel's default will be used.
1304 <term><varname>QuickAck=
</varname></term>
1306 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1311 <term><varname>FastOpenNoCookie=
</varname></term>
1313 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1314 When unset, the kernel's default will be used.
1319 <term><varname>TTLPropagate=
</varname></term>
1321 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1322 When unset, the kernel's default will be used.
1327 <term><varname>MTUBytes=
</varname></term>
1329 <para>The maximum transmission unit in bytes to set for the
1330 route. The usual suffixes K, M, G, are supported and are
1331 understood to the base of
1024.
</para>
1332 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1333 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1337 <term><varname>IPServiceType=
</varname></term>
1339 <para>Takes string;
<literal>CS6
</literal> or
<literal>CS4
</literal>. Used to set IP
1340 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.
</para>
1344 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1346 <para>Configures multipath route. Multipath routing is the technique of using multiple
1347 alternative paths through a network. Takes gateway address. Optionally, takes a network
1348 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for
1349 this multipath route separated with whitespace. This setting can be specified multiple
1350 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
1357 <title>[DHCPv4] Section Options
</title>
1358 <para>The
<literal>[DHCPv4]
</literal> section configures the
1359 DHCPv4 client, if it is enabled with the
1360 <varname>DHCP=
</varname> setting described above:
</para>
1362 <variablelist class='network-directives'
>
1364 <term><varname>UseDNS=
</varname></term>
1366 <para>When true (the default), the DNS servers received
1367 from the DHCP server will be used and take precedence over
1368 any statically configured ones.
</para>
1370 <para>This corresponds to the
<option>nameserver
</option>
1371 option in
<citerefentry
1372 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1376 <term><varname>RoutesToDNS=
</varname></term>
1378 <para>When true, the routes to the DNS servers received from the DHCP server will be
1379 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored.
1380 Defaults to false.
</para>
1384 <term><varname>UseNTP=
</varname></term>
1386 <para>When true (the default), the NTP servers received
1387 from the DHCP server will be used by systemd-timesyncd
1388 and take precedence over any statically configured ones.
</para>
1392 <term><varname>UseSIP=
</varname></term>
1394 <para>When true (the default), the SIP servers received
1395 from the DHCP server will be saved at the state files and can be
1396 read via
<function>sd_network_link_get_sip_servers()
</function> function.
</para>
1401 <term><varname>UseMTU=
</varname></term>
1403 <para>When true, the interface maximum transmission unit
1404 from the DHCP server will be used on the current link.
1405 If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
1406 Defaults to false.
</para>
1410 <term><varname>Anonymize=
</varname></term>
1412 <para>Takes a boolean. When true, the options sent to the DHCP server will
1413 follow the
<ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink>
1414 (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying information.
1415 Defaults to false.
</para>
1417 <para>This option should only be set to true when
1418 <varname>MACAddressPolicy=
</varname> is set to
<literal>random
</literal>
1420 project='man-pages'
><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
1422 <para>Note that this configuration will overwrite others.
1423 In concrete, the following variables will be ignored:
1424 <varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1425 <varname>UseRoutes=
</varname>,
<varname>UseMTU=
</varname>,
1426 <varname>VendorClassIdentifier=
</varname>,
<varname>UseTimezone=
</varname>.
</para>
1428 <para>With this option enabled DHCP requests will mimic those generated by Microsoft Windows, in
1429 order to reduce the ability to fingerprint and recognize installations. This means DHCP request
1430 sizes will grow and lease data will be more comprehensive than normally, though most of the
1431 requested data is not actually used.
</para>
1435 <term><varname>SendHostname=
</varname></term>
1437 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1438 Note that the machine's hostname must consist only of
7-bit ASCII lower-case characters and
1439 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1440 sent even if this is set to true.
</para>
1445 <term><varname>MUDURL=
</varname></term>
1447 <para>When configured, the Manufacturer Usage Descriptions (MUD) URL will be sent to the
1448 DHCPv4 server. Takes an URL of length up to
255 characters. A superficial verification that
1449 the string is a valid URL will be performed. DHCPv4 clients are intended to have at most one
1450 MUD URL associated with them. See
1451 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
1456 <term><varname>UseHostname=
</varname></term>
1458 <para>When true (the default), the hostname received from
1459 the DHCP server will be set as the transient hostname of the system.
1464 <term><varname>Hostname=
</varname></term>
1466 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1467 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1468 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1472 <term><varname>UseDomains=
</varname></term>
1474 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1475 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1476 the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name received from
1477 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1478 the
<option>Domains=
</option> setting when the argument is prefixed with
<literal>~
</literal>. Defaults to
1481 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1482 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
1483 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1484 single-label names.
</para>
1486 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1487 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1491 <term><varname>UseRoutes=
</varname></term>
1493 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1494 routing table with a metric of
1024, and a scope of
"global",
"link" or
"host", depending on the route's
1495 destination and gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the
1496 link's own address, the scope will be set to
"host". Otherwise if the gateway is null (a direct route), a
1497 "link" scope will be used. For anything else, scope defaults to
"global".
</para>
1501 <term><varname>UseGateway=
</varname></term>
1503 <para>When true, the gateway will be requested from the DHCP server and added to the routing table with a
1504 metric of
1024, and a scope of
"link". When unset, the value specified with
<option>UseRoutes=
</option>
1509 <term><varname>UseTimezone=
</varname></term>
1511 <listitem><para>When true, the timezone received from the
1512 DHCP server will be set as timezone of the local
1513 system. Defaults to
<literal>no
</literal>.
</para></listitem>
1517 <term><varname>ClientIdentifier=
</varname></term>
1519 <para>The DHCPv4 client identifier to use. Takes one of
<literal>mac
</literal>,
<literal>duid
</literal> or
<literal>duid-only
</literal>.
1520 If set to
<literal>mac
</literal>, the MAC address of the link is used.
1521 If set to
<literal>duid
</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1522 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.
1523 Defaults to
<literal>duid
</literal>.
</para>
1528 <term><varname>VendorClassIdentifier=
</varname></term>
1530 <para>The vendor class identifier used to identify vendor
1531 type and configuration.
</para>
1536 <term><varname>UserClass=
</varname></term>
1538 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1539 it represents. The information contained in this option is a string that represents the user class of which
1540 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1541 service to classify clients. Takes a whitespace-separated list of strings.
</para>
1546 <term><varname>MaxAttempts=
</varname></term>
1548 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1549 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>.
1550 Note that the time between retries is increased exponentially, so the network will not be
1551 overloaded even if this number is high.
</para>
1556 <term><varname>DUIDType=
</varname></term>
1558 <para>Override the global
<varname>DUIDType
</varname> setting for this network. See
1559 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1560 for a description of possible values.
</para>
1565 <term><varname>DUIDRawData=
</varname></term>
1567 <para>Override the global
<varname>DUIDRawData
</varname> setting for this network. See
1568 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1569 for a description of possible values.
</para>
1574 <term><varname>IAID=
</varname></term>
1576 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned integer.
</para>
1581 <term><varname>RequestBroadcast=
</varname></term>
1583 <para>Request the server to use broadcast messages before
1584 the IP address has been configured. This is necessary for
1585 devices that cannot receive RAW packets, or that cannot
1586 receive packets at all before an IP address has been
1587 configured. On the other hand, this must not be enabled on
1588 networks where broadcasts are filtered out.
</para>
1593 <term><varname>RouteMetric=
</varname></term>
1595 <para>Set the routing metric for routes specified by the
1601 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1603 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1604 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1606 <para>When used in combination with
<varname>VRF=
</varname> the
1607 VRF's routing table is used unless this parameter is specified.
1613 <term><varname>RouteMTUBytes=
</varname></term>
1615 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.
</para>
1620 <term><varname>ListenPort=
</varname></term>
1622 <para>Allow setting custom port for the DHCP client to listen on.
</para>
1627 <term><varname>FallbackLeaseLifetimeSec=
</varname></term>
1629 <para>Allows to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease lifetime.
1630 Takes one of
<literal>forever
</literal> or
<literal>infinity
</literal> means that the address
1631 never expires. Defaults to unset.
</para>
1636 <term><varname>SendRelease=
</varname></term>
1638 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops.
1639 Defaults to true.
</para>
1644 <term><varname>SendDecline=
</varname></term>
1646 <para>A boolean. When
<literal>true
</literal>, DHCPv4 clients receives IP address from DHCP server.
1647 After new IP is received, DHCPv4 performs IPv4 Duplicate Address Detection. If duplicate use of IP is detected
1648 the DHCPv4 client rejects the IP by sending a DHCPDECLINE packet DHCP clients try to obtain an IP address again.
1649 See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
1650 Defaults to
<literal>unset
</literal>.
</para>
1655 <term><varname>BlackList=
</varname></term>
1657 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are rejected.
</para>
1662 <term><varname>RequestOptions=
</varname></term>
1664 <para>When configured, allows to set arbitrary request options in the DHCPv4 request options list and will be
1665 sent to the DHCPV4 server. A whitespace-separated list of integers in the range
1.
.254. Defaults to unset.
</para>
1670 <term><varname>SendOption=
</varname></term>
1672 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data type
1673 and data separated with a colon
1674 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1675 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1676 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1677 <literal>string
</literal>. Special characters in the data string may be escaped using
1678 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1679 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1680 then all options specified earlier are cleared. Defaults to unset.
</para>
1685 <term><varname>SendVendorOption=
</varname></term>
1687 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data type
1688 and data separated with a colon
1689 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1690 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1691 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1692 <literal>string
</literal>. Special characters in the data string may be escaped using
1693 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1694 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1695 then all options specified earlier are cleared. Defaults to unset.
</para>
1702 <title>[DHCPv6] Section Options
</title>
1703 <para>The
<literal>[DHCPv6]
</literal> section configures the DHCPv6 client, if it is enabled with the
1704 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
</para>
1706 <variablelist class='network-directives'
>
1708 <term><varname>UseDNS=
</varname></term>
1709 <term><varname>UseNTP=
</varname></term>
1711 <para>As in the
<literal>[DHCPv4]
</literal> section.
</para>
1716 <term><varname>RapidCommit=
</varname></term>
1718 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1719 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1720 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1721 four-method exchange (solicit, advertise, request, and reply). The two-message exchange provides
1722 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1723 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
1724 Defaults to true.
</para>
1729 <term><varname>MUDURL=
</varname></term>
1731 <para>When configured, the Manufacturer Usage Descriptions (MUD) URL will be sent to the DHCPV6 server.
1732 Takes an URL of length up to
255 characters. A superficial verification that the string is a valid URL
1733 will be performed. DHCPv6 clients are intended to have at most one MUD URL associated with them. See
1734 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
1739 <term><varname>RequestOptions=
</varname></term>
1741 <para>When configured, allows to set arbitrary request options in the DHCPv6 request options list and will
1742 sent to the DHCPV6 server. A whitespace-separated list of integers in the range
1.
.254. Defaults to unset.
</para>
1747 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
1749 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
1750 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
1751 makes DHCPv6 request network information in a stateless manner using a two-message Information
1752 Request and Information Reply message exchange.
1753 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
1754 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
1755 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
1756 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
1757 By default this option is set to 'false', enable it if no prefixes are delegated when the device
1758 should be acting as a CE router.
</para>
1763 <term><varname>PrefixDelegationHint=
</varname></term>
1765 <para>Takes an IPv6 address with prefix length as
<varname>Address=
</varname> in
1766 the
"[Network]" section. Specifies the DHCPv6 client for the requesting router to include
1767 a prefix-hint in the DHCPv6 solicitation. Prefix ranges
1.
.128. Defaults to unset.
</para>
1772 <term><varname>WithoutRA=
</varname></term>
1774 <para>When true, DHCPv6 client starts without router advertisements's managed or other address configuration flag.
1775 Defaults to false.
</para>
1780 <term><varname>SendOption=
</varname></term>
1782 <para>As in the
<literal>[DHCPv4]
</literal> section, however because DHCPv6 uses
16-bit fields to store
1783 option numbers, the option number is an integer in the range
1.
.65536.
</para>
1788 <term><varname>UserClass=
</varname></term>
1790 <para>A DHCPv6 client can use User Class option to identify the type or category of user or applications
1791 it represents. The information contained in this option is a string that represents the user class of which
1792 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1793 service to classify clients. Special characters in the data string may be escaped using
1794 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1795 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1796 then all options specified earlier are cleared. Takes a whitespace-separated list of strings. Note that
1797 currently NUL bytes are not allowed.
</para>
1802 <term><varname>VendorClass=
</varname></term>
1804 <para>A DHCPv6 client can use VendorClass option to identify the vendor that
1805 manufactured the hardware on which the client is running. The information
1806 contained in the data area of this option is contained in one or more opaque
1807 fields that identify details of the hardware configuration. Takes a
1808 whitespace-separated list of strings.
</para>
1815 <title>[IPv6AcceptRA] Section Options
</title>
1816 <para>The
<literal>[IPv6AcceptRA]
</literal> section configures the IPv6 Router Advertisement
1817 (RA) client, if it is enabled with the
<varname>IPv6AcceptRA=
</varname> setting described
1820 <variablelist class='network-directives'
>
1822 <term><varname>UseDNS=
</varname></term>
1824 <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
1825 precedence over any statically configured ones.
</para>
1827 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
1828 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1833 <term><varname>UseDomains=
</varname></term>
1835 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1836 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
1837 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
1838 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
1839 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
1840 <literal>~
</literal>. Defaults to false.
</para>
1842 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1843 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
1844 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1845 single-label names.
</para>
1847 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1848 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1853 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1855 <para>The table identifier for the routes received in the Router Advertisement
1856 (a number between
1 and
4294967295, or
0 to unset).
1857 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1863 <term><varname>UseAutonomousPrefix=
</varname></term>
1865 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
1866 precedence over any statically configured ones.
</para>
1871 <term><varname>UseOnLinkPrefix=
</varname></term>
1873 <para>When true (the default), the onlink prefix received in the Router Advertisement will be used and take
1874 precedence over any statically configured ones.
</para>
1879 <term><varname>BlackList=
</varname></term>
1881 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router advertisements in the list are ignored.
</para>
1886 <term><varname>DHCPv6Client=
</varname></term>
1888 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true (the default), the DHCPv6 client will be started when the
1889 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
1890 managed or other information flag in the RA.
</para>
1897 <title>[DHCPServer] Section Options
</title>
1898 <para>The
<literal>[DHCPServer]
</literal> section contains
1899 settings for the DHCP server, if enabled via the
1900 <varname>DHCPServer=
</varname> option described above:
</para>
1902 <variablelist class='network-directives'
>
1905 <term><varname>PoolOffset=
</varname></term>
1906 <term><varname>PoolSize=
</varname></term>
1908 <listitem><para>Configures the pool of addresses to hand out. The pool
1909 is a contiguous sequence of IP addresses in the subnet configured for
1910 the server address, which does not include the subnet nor the broadcast
1911 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
1912 from the start of subnet, or zero to use the default value.
1913 <varname>PoolSize=
</varname> takes the number of IP addresses in the
1914 pool or zero to use the default value. By default, the pool starts at
1915 the first address after the subnet address and takes up the rest of
1916 the subnet, excluding the broadcast address. If the pool includes
1917 the server address (the default), this is reserved and not handed
1918 out to clients.
</para></listitem>
1922 <term><varname>DefaultLeaseTimeSec=
</varname></term>
1923 <term><varname>MaxLeaseTimeSec=
</varname></term>
1925 <listitem><para>Control the default and maximum DHCP lease
1926 time to pass to clients. These settings take time values in seconds or
1927 another common time unit, depending on the suffix. The default
1928 lease time is used for clients that did not ask for a specific
1929 lease time. If a client asks for a lease time longer than the
1930 maximum lease time, it is automatically shortened to the
1931 specified time. The default lease time defaults to
1h, the
1932 maximum lease time to
12h. Shorter lease times are beneficial
1933 if the configuration data in DHCP leases changes frequently
1934 and clients shall learn the new settings with shorter
1935 latencies. Longer lease times reduce the generated DHCP
1936 network traffic.
</para></listitem>
1940 <term><varname>EmitDNS=
</varname></term>
1941 <term><varname>DNS=
</varname></term>
1943 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1944 to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
1945 The DNS servers to pass to clients may be configured with the
1946 <varname>DNS=
</varname> option, which takes a list of IPv4
1947 addresses. If the
<varname>EmitDNS=
</varname> option is
1948 enabled but no servers configured, the servers are
1949 automatically propagated from an
"uplink" interface that has
1950 appropriate servers set. The
"uplink" interface is determined
1951 by the default route of the system with the highest
1952 priority. Note that this information is acquired at the time
1953 the lease is handed out, and does not take uplink interfaces
1954 into account that acquire DNS or NTP server information at a
1955 later point. DNS server propagation does not take
1956 <filename>/etc/resolv.conf
</filename> into account. Also, note
1957 that the leases are not refreshed if the uplink network
1958 configuration changes. To ensure clients regularly acquire the
1959 most current uplink DNS server information, it is thus
1960 advisable to shorten the DHCP lease time via
1961 <varname>MaxLeaseTimeSec=
</varname> described
1962 above.
</para></listitem>
1966 <term><varname>EmitNTP=
</varname></term>
1967 <term><varname>NTP=
</varname></term>
1969 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1970 <varname>DNS=
</varname> settings described above, these
1971 settings configure whether and what NTP server information
1972 shall be emitted as part of the DHCP lease. The same syntax,
1973 propagation semantics and defaults apply as for
1974 <varname>EmitDNS=
</varname> and
1975 <varname>DNS=
</varname>.
</para></listitem>
1979 <term><varname>EmitSIP=
</varname></term>
1980 <term><varname>SIP=
</varname></term>
1982 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1983 <varname>DNS=
</varname> settings described above, these
1984 settings configure whether and what SIP server information
1985 shall be emitted as part of the DHCP lease. The same syntax,
1986 propagation semantics and defaults apply as for
1987 <varname>EmitDNS=
</varname> and
1988 <varname>DNS=
</varname>.
</para></listitem>
1992 <term><varname>POP3Servers=
</varname></term>
1994 <listitem><para>Similar to the
<varname>DNS=
</varname> setting described above, this setting
1995 configures whether and what POP3 server information shall be emitted as part of the DHCP lease. The
1996 same syntax, propagation semantics and defaults apply as for
1997 <varname>DNS=
</varname>.
</para></listitem>
2001 <term><varname>SMTPServers=
</varname></term>
2003 <listitem><para>Similar to the
<varname>DNS=
</varname> setting described above, this
2004 setting configures whether and what SMTP server information shall be emitted as part of
2005 the DHCP lease. The same syntax, propagation semantics and defaults apply as for
2006 <varname>DNS=
</varname>.
</para></listitem>
2010 <term><varname>LPRServers=
</varname></term>
2012 <listitem><para>Similar to the
<varname>DNS=
</varname> setting described above, this
2013 setting configures whether and what LPR (line printer) server information shall be emitted
2014 as part of the DHCP lease. The same syntax, propagation semantics and defaults apply as for
2015 <varname>DNS=
</varname>.
</para></listitem>
2019 <term><varname>EmitRouter=
</varname></term>
2021 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
2022 setting described above, this setting configures whether the
2023 DHCP lease should contain the router option. The same syntax,
2024 propagation semantics and defaults apply as for
2025 <varname>EmitDNS=
</varname>.
</para></listitem>
2029 <term><varname>EmitTimezone=
</varname></term>
2030 <term><varname>Timezone=
</varname></term>
2032 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
2033 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
2034 <varname>Timezone=
</varname> setting takes a timezone string
2035 (such as
<literal>Europe/Berlin
</literal> or
2036 <literal>UTC
</literal>) to pass to clients. If no explicit
2037 timezone is set, the system timezone of the local host is
2038 propagated, as determined by the
2039 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
2043 <term><varname>SendOption=
</varname></term>
2045 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
2046 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2047 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
2048 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>,
<literal>ipv6address
</literal>, or
2049 <literal>string
</literal>. Special characters in the data string may be escaped using
2050 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2051 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2052 then all options specified earlier are cleared. Defaults to unset.
</para>
2057 <term><varname>SendVendorOption=
</varname></term>
2059 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
2060 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
2061 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
2062 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
2063 <literal>string
</literal>. Special characters in the data string may be escaped using
2064 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
2065 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
2066 then all options specified earlier are cleared. Defaults to unset.
</para>
2074 <title>[IPv6PrefixDelegation] Section Options
</title>
2075 <para>The
<literal>[IPv6PrefixDelegation]
</literal> section contains
2076 settings for sending IPv6 Router Advertisements and whether to act as
2077 a router, if enabled via the
<varname>IPv6PrefixDelegation=
</varname>
2078 option described above. IPv6 network prefixes are defined with one or
2079 more
<literal>[IPv6Prefix]
</literal> sections.
</para>
2081 <variablelist class='network-directives'
>
2084 <term><varname>Managed=
</varname></term>
2085 <term><varname>OtherInformation=
</varname></term>
2087 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
2088 addresses on the network link when
<varname>Managed=
</varname>
2089 is set to
<literal>true
</literal> or if only additional network
2090 information can be obtained via DHCPv6 for the network link when
2091 <varname>OtherInformation=
</varname> is set to
2092 <literal>true
</literal>. Both settings default to
2093 <literal>false
</literal>, which means that a DHCPv6 server is not being
2094 used.
</para></listitem>
2098 <term><varname>RouterLifetimeSec=
</varname></term>
2100 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. If set,
2101 this host also announces itself in Router Advertisements as an IPv6
2102 router for the network link. When unset, the host is not acting as a router.
</para>
2107 <term><varname>RouterPreference=
</varname></term>
2109 <listitem><para>Configures IPv6 router preference if
2110 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
2111 <literal>high
</literal>,
<literal>medium
</literal> and
2112 <literal>low
</literal>, with
<literal>normal
</literal> and
2113 <literal>default
</literal> added as synonyms for
2114 <literal>medium
</literal> just to make configuration easier. See
2115 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2116 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
2120 <term><varname>EmitDNS=
</varname></term>
2121 <term><varname>DNS=
</varname></term>
2123 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
2124 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is
2125 true.
<varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that
2126 case the IPv6 link local address is distributed. If
<varname>DNS=
</varname> is empty, DNS
2127 servers are read from the
<literal>[Network]
</literal> section. If the
2128 <literal>[Network]
</literal> section does not contain any DNS servers either, DNS servers from
2129 the uplink with the highest priority default route are used. When
<varname>EmitDNS=
</varname>
2130 is false, no DNS server information is sent in Router Advertisement messages.
2131 <varname>EmitDNS=
</varname> defaults to true.
2136 <term><varname>EmitDomains=
</varname></term>
2137 <term><varname>Domains=
</varname></term>
2139 <listitem><para>A list of DNS search domains distributed via Router
2140 Advertisement messages when
<varname>EmitDomains=
</varname> is true. If
2141 <varname>Domains=
</varname> is empty, DNS search domains are read from the
2142 <literal>[Network]
</literal> section. If the
<literal>[Network]
</literal>
2143 section does not contain any DNS search domains either, DNS search
2144 domains from the uplink with the highest priority default route are
2145 used. When
<varname>EmitDomains=
</varname> is false, no DNS search domain
2146 information is sent in Router Advertisement messages.
2147 <varname>EmitDomains=
</varname> defaults to true.
2152 <term><varname>DNSLifetimeSec=
</varname></term>
2154 <listitem><para>Lifetime in seconds for the DNS server addresses listed
2155 in
<varname>DNS=
</varname> and search domains listed in
2156 <varname>Domains=
</varname>.
</para></listitem>
2163 <title>[IPv6Prefix] Section Options
</title>
2164 <para>One or more
<literal>[IPv6Prefix]
</literal> sections contain the IPv6
2165 prefixes that are announced via Router Advertisements. See
2166 <ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink>
2167 for further details.
</para>
2169 <variablelist class='network-directives'
>
2172 <term><varname>AddressAutoconfiguration=
</varname></term>
2173 <term><varname>OnLink=
</varname></term>
2175 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
2176 autoconfigured with this prefix and whether the prefix can be used for
2177 onlink determination. Both settings default to
<literal>true
</literal>
2178 in order to ease configuration.
2183 <term><varname>Prefix=
</varname></term>
2185 <listitem><para>The IPv6 prefix that is to be distributed to hosts.
2186 Similarly to configuring static IPv6 addresses, the setting is
2187 configured as an IPv6 prefix and its prefix length, separated by a
2188 <literal>/
</literal> character. Use multiple
2189 <literal>[IPv6Prefix]
</literal> sections to configure multiple IPv6
2190 prefixes since prefix lifetimes, address autoconfiguration and onlink
2191 status may differ from one prefix to another.
</para></listitem>
2195 <term><varname>PreferredLifetimeSec=
</varname></term>
2196 <term><varname>ValidLifetimeSec=
</varname></term>
2198 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2199 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
2200 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
2201 to
2592000 seconds (
30 days).
</para></listitem>
2205 <term><varname>Assign=
</varname></term>
2206 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
2213 <title>[IPv6RoutePrefix] Section Options
</title>
2214 <para>One or more
<literal>[IPv6RoutePrefix]
</literal> sections contain the IPv6
2215 prefix routes that are announced via Router Advertisements. See
2216 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2217 for further details.
</para>
2219 <variablelist class='network-directives'
>
2222 <term><varname>Route=
</varname></term>
2224 <listitem><para>The IPv6 route that is to be distributed to hosts.
2225 Similarly to configuring static IPv6 routes, the setting is
2226 configured as an IPv6 prefix routes and its prefix route length,
2227 separated by a
<literal>/
</literal> character. Use multiple
2228 <literal>[IPv6PrefixRoutes]
</literal> sections to configure multiple IPv6
2229 prefix routes.
</para></listitem>
2233 <term><varname>LifetimeSec=
</varname></term>
2235 <listitem><para>Lifetime for the route prefix measured in
2236 seconds.
<varname>LifetimeSec=
</varname> defaults to
604800 seconds (one week).
2244 <title>[Bridge] Section Options
</title>
2245 <para>The
<literal>[Bridge]
</literal> section accepts the
2246 following keys.
</para>
2247 <variablelist class='network-directives'
>
2249 <term><varname>UnicastFlood=
</varname></term>
2251 <para>Takes a boolean. Controls whether the bridge should flood
2252 traffic for which an FDB entry is missing and the destination
2253 is unknown through this port. When unset, the kernel's default will be used.
2258 <term><varname>MulticastFlood=
</varname></term>
2260 <para>Takes a boolean. Controls whether the bridge should flood
2261 traffic for which an MDB entry is missing and the destination
2262 is unknown through this port. When unset, the kernel's default will be used.
2267 <term><varname>MulticastToUnicast=
</varname></term>
2269 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2270 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2271 When unset, the kernel's default will be used.
2276 <term><varname>NeighborSuppression=
</varname></term>
2278 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2279 this port. When unset, the kernel's default will be used.
2284 <term><varname>Learning=
</varname></term>
2286 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2287 this port. When unset, the kernel's default will be used.
2292 <term><varname>HairPin=
</varname></term>
2294 <para>Takes a boolean. Configures whether traffic may be sent back
2295 out of the port on which it was received. When this flag is false, and the bridge
2296 will not forward traffic back out of the receiving port.
2297 When unset, the kernel's default will be used.
</para>
2301 <term><varname>UseBPDU=
</varname></term>
2303 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2304 processed by the bridge port. When unset, the kernel's default will be used.
</para>
2308 <term><varname>FastLeave=
</varname></term>
2310 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2311 traffic on a port that receives an IGMP Leave message. It is only used with
2312 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
2316 <term><varname>AllowPortToBeRoot=
</varname></term>
2318 <para>Takes a boolean. Configures whether a given port is allowed to
2319 become a root port. Only used when STP is enabled on the bridge.
2320 When unset, the kernel's default will be used.
</para>
2324 <term><varname>ProxyARP=
</varname></term>
2326 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2327 When unset, the kernel's default will be used.
</para>
2331 <term><varname>ProxyARPWiFi=
</varname></term>
2333 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2334 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
2335 When unset, the kernel's default will be used.
</para>
2339 <term><varname>MulticastRouter=
</varname></term>
2341 <para>Configures this port for having multicast routers attached. A port with a multicast
2342 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
2343 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
2344 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
2345 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
2346 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
2350 <term><varname>Cost=
</varname></term>
2352 <para>Sets the
"cost" of sending packets of this interface.
2353 Each port in a bridge may have a different speed and the cost
2354 is used to decide which link to use. Faster interfaces
2355 should have lower costs. It is an integer value between
1 and
2360 <term><varname>Priority=
</varname></term>
2362 <para>Sets the
"priority" of sending packets on this interface.
2363 Each port in a bridge may have a different priority which is used
2364 to decide which link to use. Lower value means higher priority.
2365 It is an integer value between
0 to
63. Networkd does not set any
2366 default, meaning the kernel default value of
32 is used.
</para>
2372 <title>[BridgeFDB] Section Options
</title>
2373 <para>The
<literal>[BridgeFDB]
</literal> section manages the
2374 forwarding database table of a port and accepts the following
2375 keys. Specify several
<literal>[BridgeFDB]
</literal> sections to
2376 configure several static MAC table entries.
</para>
2378 <variablelist class='network-directives'
>
2380 <term><varname>MACAddress=
</varname></term>
2382 <para>As in the
<literal>[Network]
</literal> section. This
2383 key is mandatory.
</para>
2387 <term><varname>Destination=
</varname></term>
2389 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
2393 <term><varname>VLANId=
</varname></term>
2395 <para>The VLAN ID for the new static MAC table entry. If
2396 omitted, no VLAN ID information is appended to the new static MAC
2401 <term><varname>VNI=
</varname></term>
2403 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2404 the remote VXLAN tunnel endpoint. Takes a number in the range
1-
16777215.
2405 Defaults to unset.
</para>
2409 <term><varname>AssociatedWith=
</varname></term>
2411 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
2412 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
2413 <literal>use
</literal> means the address is in use. User space can use this option to
2414 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
2415 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
2416 means the address is associated with master devices fdb.
<literal>router
</literal> means
2417 the destination address is associated with a router. Note that it's valid if the referenced
2418 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
2425 <title>[LLDP] Section Options
</title>
2426 <para>The
<literal>[LLDP]
</literal> section manages the Link Layer Discovery Protocol (LLDP) and accepts the
2427 following keys.
</para>
2428 <variablelist class='network-directives'
>
2430 <term><varname>MUDURL=
</varname></term>
2432 <para>Controls support for Ethernet LLDP packet's Manufacturer Usage Description (MUD). MUD is an embedded software
2433 standard defined by the IETF that allows IoT Device makers to advertise device specifications, including the intended
2434 communication patterns for their device when it connects to the network. The network can then use this intent to author
2435 a context-specific access policy, so the device functions only within those parameters. Takes an URL of length up to
255
2436 characters. A superficial verification that the string is a valid URL
2437 will be performed. See
2438 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink> for details. The MUD URL received
2439 from the LLDP packets will be saved at the state files and can be read via
2440 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
2447 <title>[CAN] Section Options
</title>
2448 <para>The
<literal>[CAN]
</literal> section manages the Controller Area Network (CAN bus) and accepts the
2449 following keys.
</para>
2450 <variablelist class='network-directives'
>
2452 <term><varname>BitRate=
</varname></term>
2454 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
2455 be used here. Takes a number in the range
1.
.4294967295.
</para>
2459 <term><varname>SamplePoint=
</varname></term>
2461 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2462 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2466 <term><varname>DataBitRate=
</varname></term>
2467 <term><varname>DataSamplePoint=
</varname></term>
2469 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
2470 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
2474 <term><varname>FDMode=
</varname></term>
2476 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
2477 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
2478 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys.
</para>
2482 <term><varname>FDNonISO=
</varname></term>
2484 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
2485 interface. When unset, the kernel's default will be used.
</para>
2489 <term><varname>RestartSec=
</varname></term>
2491 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2492 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2493 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2494 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2495 automatic restart off. By default automatic restart is disabled.
</para>
2499 <term><varname>Termination=
</varname></term>
2501 <para>Takes a boolean. When
<literal>yes
</literal>, the termination resistor will be selected for
2502 the bias network. When unset, the kernel's default will be used.
</para>
2506 <term><varname>TripleSampling=
</varname></term>
2508 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2509 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
2513 <term><varname>ListenOnly=
</varname></term>
2515 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
2516 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
2517 bit. Listen-only mode is important to debug CAN networks without interfering with the
2518 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
2526 <title>[QDisc] Section Options
</title>
2527 <para>The
<literal>[QDisc]
</literal> section manages the traffic control queueing discipline (qdisc).
</para>
2529 <variablelist class='network-directives'
>
2531 <term><varname>Parent=
</varname></term>
2533 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
2534 or
<literal>ingress
</literal>. This is mandatory.
</para>
2538 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2543 <title>[NetworkEmulator] Section Options
</title>
2544 <para>The
<literal>[NetworkEmulator]
</literal> section manages the queueing discipline (qdisc) of
2545 the network emulator. It can be used to configure the kernel packet scheduler and simulate packet
2546 delay and loss for UDP or TCP applications, or limit the bandwidth usage of a particular service to
2547 simulate internet connections.
</para>
2549 <variablelist class='network-directives'
>
2550 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2551 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2554 <term><varname>DelaySec=
</varname></term>
2556 <para>Specifies the fixed amount of delay to be added to all packets going out of the
2557 interface. Defaults to unset.
</para>
2562 <term><varname>DelayJitterSec=
</varname></term>
2564 <para>Specifies the chosen delay to be added to the packets outgoing to the network
2565 interface. Defaults to unset.
</para>
2570 <term><varname>PacketLimit=
</varname></term>
2572 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
2573 An unsigned integer ranges
0 to
4294967294. Defaults to
1000.
</para>
2578 <term><varname>LossRate=
</varname></term>
2580 <para>Specifies an independent loss probability to be added to the packets outgoing from the
2581 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2586 <term><varname>DuplicateRate=
</varname></term>
2588 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
2589 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2596 <title>[TokenBucketFilter] Section Options
</title>
2597 <para>The
<literal>[TokenBucketFilter]
</literal> section manages the queueing discipline (qdisc) of
2598 token bucket filter (tbf).
</para>
2600 <variablelist class='network-directives'
>
2601 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2602 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2605 <term><varname>LatencySec=
</varname></term>
2607 <para>Specifies the latency parameter, which specifies the maximum amount of time a
2608 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
2613 <term><varname>LimitSize=
</varname></term>
2615 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
2616 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
2617 respectively, to the base of
1000. Defaults to unset.
</para>
2622 <term><varname>Burst=
</varname></term>
2624 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
2625 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
2626 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to
2632 <term><varname>Rate=
</varname></term>
2634 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
2635 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
2636 Defaults to unset.
</para>
2641 <term><varname>MPUBytes=
</varname></term>
2643 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
2644 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2645 Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to zero.
</para>
2650 <term><varname>PeakRate=
</varname></term>
2652 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
2653 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2654 1000. Defaults to unset.
</para>
2659 <term><varname>MTUBytes=
</varname></term>
2661 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
2662 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000.
2663 Defaults to unset.
</para>
2670 <title>[PIE] Section Options
</title>
2671 <para>The
<literal>[PIE]
</literal> section manages the queueing discipline
2672 (qdisc) of Proportional Integral controller-Enhanced (PIE).
</para>
2674 <variablelist class='network-directives'
>
2675 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2676 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2679 <term><varname>PacketLimit=
</varname></term>
2681 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2682 dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2689 <title>[StochasticFairBlue] Section Options
</title>
2690 <para>The
<literal>[StochasticFairBlue]
</literal> section manages the queueing discipline
2691 (qdisc) of stochastic fair blue (sfb).
</para>
2693 <variablelist class='network-directives'
>
2694 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2695 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2698 <term><varname>PacketLimit=
</varname></term>
2700 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2701 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2708 <title>[StochasticFairnessQueueing] Section Options
</title>
2709 <para>The
<literal>[StochasticFairnessQueueing]
</literal> section manages the queueing discipline
2710 (qdisc) of stochastic fairness queueing (sfq).
</para>
2712 <variablelist class='network-directives'
>
2713 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2714 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2717 <term><varname>PerturbPeriodSec=
</varname></term>
2719 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
2726 <title>[BFIFO] Section Options
</title>
2727 <para>The
<literal>[BFIFO]
</literal> section manages the queueing discipline (qdisc) of
2728 Byte limited Packet First In First Out (bfifo).
</para>
2730 <variablelist class='network-directives'
>
2731 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2732 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2735 <term><varname>LimitSize=
</varname></term>
2737 <para>Specifies the hard limit on the FIFO size in bytes. The size limit (a buffer size) to prevent it
2738 from overflowing in case it is unable to dequeue packets as quickly as it receives them. When this limit
2739 is reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed as
2740 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2747 <title>[PFIFO] Section Options
</title>
2748 <para>The
<literal>[PFIFO]
</literal> section manages the queueing discipline (qdisc) of
2749 Packet First In First Out (pfifo).
</para>
2751 <variablelist class='network-directives'
>
2752 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2753 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2756 <term><varname>PacketLimit=
</varname></term>
2758 <para>Specifies the hard limit on the FIFO size in number of packets. The size limit (a buffer size) to prevent it
2759 from overflowing in case it is unable to dequeue packets as quickly as it receives them. When this limit is reached,
2760 incoming packets are dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2767 <title>[PFIFOHeadDrop] Section Options
</title>
2768 <para>The
<literal>[PFIFOHeadDrop]
</literal> section manages the queueing discipline (qdisc) of
2769 Packet First In First Out Head Drop (pfifo_head_drop).
</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>As in
<literal>[PFIFO]
</literal> section.
</para></listitem>
2784 <title>[PFIFOFast] Section Options
</title>
2785 <para>The
<literal>[PFIFOFast]
</literal> section manages the queueing discipline (qdisc) of
2786 Packet First In First Out Fast (pfifo_fast).
</para>
2788 <variablelist class='network-directives'
>
2789 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2790 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2795 <title>[CAKE] Section Options
</title>
2796 <para>The
<literal>[CAKE]
</literal> section manages the queueing discipline (qdisc) of
2797 Common Applications Kept Enhanced (CAKE).
</para>
2799 <variablelist class='network-directives'
>
2800 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2801 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2804 <term><varname>Overhead=
</varname></term>
2806 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative.
2807 Takes an integer ranges -
64 to
256. Defaults to unset and kernel's default is used.
</para>
2812 <term><varname>Bandwidth=
</varname></term>
2814 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
2815 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
2816 unset and kernel's default is used.
</para>
2823 <title>[ControlledDelay] Section Options
</title>
2824 <para>The
<literal>[ControlledDelay]
</literal> section manages the queueing discipline (qdisc) of
2825 controlled delay (CoDel).
</para>
2827 <variablelist class='network-directives'
>
2828 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2829 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2832 <term><varname>PacketLimit=
</varname></term>
2834 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2835 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2840 <term><varname>TargetSec=
</varname></term>
2842 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2843 Defaults to unset and kernel's default is used.
</para>
2848 <term><varname>IntervalSec=
</varname></term>
2850 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2851 become too stale. Defaults to unset and kernel's default is used.
</para>
2856 <term><varname>ECN=
</varname></term>
2858 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2859 unset and kernel's default is used.
</para>
2864 <term><varname>CEThresholdSec=
</varname></term>
2866 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2867 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2874 <title>[DeficitRoundRobinScheduler] Section Options
</title>
2875 <para>The
<literal>[DeficitRoundRobinScheduler]
</literal> section manages the queueing discipline (qdisc) of
2876 Deficit Round Robin Scheduler (DRR).
</para>
2878 <variablelist class='network-directives'
>
2879 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2880 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2885 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
2886 <para>The
<literal>[DeficitRoundRobinSchedulerClass]
</literal> section manages the traffic control class of
2887 Deficit Round Robin Scheduler (DRR).
</para>
2889 <variablelist class='network-directives'
>
2890 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
2891 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
2894 <term><varname>Quantum=
</varname></term>
2896 <para>Specifies the amount of bytes a flow is allowed to dequeue before the
2897 scheduler moves to the next class. An unsigned integer ranges
1 to
4294967294.
2898 Defaults to the MTU of the interface.
</para>
2906 <title>[GenericRandomEarlyDetection] Section Options
</title>
2907 <para>The
<literal>[GenericRandomEarlyDetection]
</literal> section manages the queueing discipline
2908 (qdisc) of Generic Random Early Detection (GRED).
</para>
2910 <variablelist class='network-directives'
>
2911 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2912 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2915 <term><varname>VirtualQueues=
</varname></term>
2917 <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>
2922 <term><varname>DefaultVirtualQueue=
</varname></term>
2924 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
2925 Defaults to unset and kernel's default is used.
</para>
2930 <term><varname>GenericRIO=
</varname></term>
2932 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
2933 unset and kernel's default is used.
</para>
2940 <title>[FairQueueingControlledDelay] Section Options
</title>
2941 <para>The
<literal>[FairQueueingControlledDelay]
</literal> section manages the queueing discipline
2942 (qdisc) of fair queuing controlled delay (FQ-CoDel).
</para>
2944 <variablelist class='network-directives'
>
2945 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2946 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2949 <term><varname>PacketLimit=
</varname></term>
2951 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2952 dropped. Defaults to unset and kernel's default is used.
</para>
2957 <term><varname>MemoryLimit=
</varname></term>
2959 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
2960 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2961 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2966 <term><varname>Flows=
</varname></term>
2968 <para>Specifies the number of flows into which the incoming packets are classified.
2969 Defaults to unset and kernel's default is used.
</para>
2974 <term><varname>TargetSec=
</varname></term>
2976 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2977 Defaults to unset and kernel's default is used.
</para>
2982 <term><varname>IntervalSec=
</varname></term>
2984 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2985 become too stale. Defaults to unset and kernel's default is used.
</para>
2990 <term><varname>Quantum=
</varname></term>
2992 <para>Specifies the number of bytes used as 'deficit' in the fair queuing algorithmtimespan.
2993 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2994 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2999 <term><varname>ECN=
</varname></term>
3001 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
3002 unset and kernel's default is used.
</para>
3007 <term><varname>CEThresholdSec=
</varname></term>
3009 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3010 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3017 <title>[FairQueueing] Section Options
</title>
3018 <para>The
<literal>[FairQueueing]
</literal> section manages the queueing discipline
3019 (qdisc) of fair queue traffic policing (FQ).
</para>
3021 <variablelist class='network-directives'
>
3022 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3023 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3026 <term><varname>PacketLimit=
</varname></term>
3028 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
3029 dropped. Defaults to unset and kernel's default is used.
</para>
3034 <term><varname>FlowLimit=
</varname></term>
3036 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
3037 unset and kernel's default is used.
</para>
3042 <term><varname>Quantum=
</varname></term>
3044 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
3045 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
3046 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
3047 default is used.
</para>
3052 <term><varname>InitialQuantum=
</varname></term>
3054 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
3055 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
3056 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
3057 kernel's default is used.
</para>
3062 <term><varname>MaximumRate=
</varname></term>
3064 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
3065 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
3066 1000. Defaults to unset and kernel's default is used.
</para>
3071 <term><varname>Buckets=
</varname></term>
3073 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
3074 kernel's default is used.
</para>
3079 <term><varname>OrphanMask=
</varname></term>
3081 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
3082 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
3083 kernel's default is used.
</para>
3088 <term><varname>Pacing=
</varname></term>
3090 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
3091 default is used.
</para>
3096 <term><varname>CEThresholdSec=
</varname></term>
3098 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3099 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3106 <title>[TrivialLinkEqualizer] Section Options
</title>
3107 <para>The
<literal>[TrivialLinkEqualizer]
</literal> section manages the queueing discipline (qdisc) of
3108 trivial link equalizer (teql).
</para>
3110 <variablelist class='network-directives'
>
3111 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3112 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3115 <term><varname>Id=
</varname></term>
3117 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
3118 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
3119 <constant>max_equalizers=N+
1</constant> option must be loaded before
3120 <command>systemd-networkd
</command> is started.
</para>
3127 <title>[HierarchyTokenBucket] Section Options
</title>
3128 <para>The
<literal>[HierarchyTokenBucket]
</literal> section manages the queueing discipline (qdisc) of
3129 hierarchy token bucket (htb).
</para>
3131 <variablelist class='network-directives'
>
3132 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3133 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3136 <term><varname>DefaultClass=
</varname></term>
3138 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
3139 to the class. Defaults to unset.
</para>
3146 <title>[HierarchyTokenBucketClass] Section Options
</title>
3147 <para>The
<literal>[HierarchyTokenBucketClass]
</literal> section manages the traffic control class of
3148 hierarchy token bucket (htb).
</para>
3150 <variablelist class='network-directives'
>
3151 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3152 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3155 <term><varname>Priority=
</varname></term>
3157 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
3158 priority field are tried for packets first. This setting is mandatory.
</para>
3163 <term><varname>Rate=
</varname></term>
3165 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
3166 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
3167 to the base of
1000. This setting is mandatory.
</para>
3172 <term><varname>CeilRate=
</varname></term>
3174 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
3175 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
3176 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
3184 <title>[HeavyHitterFilter] Section Options
</title>
3185 <para>The
<literal>[HeavyHitterFilter]
</literal> section manages the queueing discipline
3186 (qdisc) of Heavy Hitter Filter (hhf).
</para>
3188 <variablelist class='network-directives'
>
3189 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3190 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3193 <term><varname>PacketLimit=
</varname></term>
3195 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
3196 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
3203 <title>[BridgeVLAN] Section Options
</title>
3204 <para>The
<literal>[BridgeVLAN]
</literal> section manages the VLAN ID configuration of a bridge port and accepts
3205 the following keys. Specify several
<literal>[BridgeVLAN]
</literal> sections to configure several VLAN entries.
3206 The
<varname>VLANFiltering=
</varname> option has to be enabled, see
<literal>[Bridge]
</literal> section in
3207 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3209 <variablelist class='network-directives'
>
3211 <term><varname>VLAN=
</varname></term>
3213 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
3214 from
1 to
4094.
</para>
3218 <term><varname>EgressUntagged=
</varname></term>
3220 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
3221 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
3222 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
3226 <term><varname>PVID=
</varname></term>
3228 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
3229 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
3230 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
3237 <title>Examples
</title>
3239 <title>Static network configuration
</title>
3241 <programlisting># /etc/systemd/network/
50-static.network
3246 Address=
192.168.0.15/
24
3247 Gateway=
192.168.0.1</programlisting>
3249 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
3250 specified gateway will be used for a default route.
</para>
3254 <title>DHCP on ethernet links
</title>
3256 <programlisting># /etc/systemd/network/
80-dhcp.network
3261 DHCP=yes
</programlisting>
3263 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
3264 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
3268 <title>IPv6 Prefix Delegation
</title>
3270 <programlisting># /etc/systemd/network/
55-ipv6-pd-upstream.network
3275 DHCP=ipv6
</programlisting>
3277 <programlisting># /etc/systemd/network/
56-ipv6-pd-downstream.network
3282 IPv6PrefixDelegation=dhcpv6
</programlisting>
3284 <para>This will enable IPv6 PD on the interface enp1s0 as an upstream interface where the
3285 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
</para>
3289 <title>A bridge with two enslaved links
</title>
3291 <programlisting># /etc/systemd/network/
25-bridge-static.network
3296 Address=
192.168.0.15/
24
3298 DNS=
192.168.0.1</programlisting>
3300 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
3305 Bridge=bridge0
</programlisting>
3307 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
3312 Bridge=bridge0
</programlisting>
3314 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
3315 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
3316 and network assigned, and a default route via the specified gateway will be
3317 added. The specified DNS server will be added to the global list of DNS resolvers.
3325 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
3341 EgressUntagged=
300-
400</programlisting>
3343 <para>This overrides the configuration specified in the previous example for the
3344 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
3345 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
3346 untagged when they leave on this interface. Untagged packets which arrive on this
3347 interface will be assigned VLAN ID
42.
</para>
3351 <title>Various tunnels
</title>
3353 <programlisting>/etc/systemd/network/
25-tunnels.network
3364 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
3370 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
3376 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
3382 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
3388 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
3389 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
3393 <title>A bond device
</title>
3395 <programlisting># /etc/systemd/network/
30-bond1.network
3403 <programlisting># /etc/systemd/network/
30-bond1.netdev
3409 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
3411 MACAddress=
52:
54:
00:e9:
64:
41
3417 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
3419 MACAddress=
52:
54:
00:e9:
64:
42
3425 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
3426 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
3427 will be used to acquire an address.
</para>
3431 <title>Virtual Routing and Forwarding (VRF)
</title>
3432 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
3433 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
3434 within the routing table defined during VRF creation. For kernels before
4.8 traffic
3435 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
3437 <programlisting># /etc/systemd/network/
25-vrf.network
3447 <title>MacVTap
</title>
3448 <para>This brings up a network interface
<literal>macvtap-test
</literal>
3449 and attaches it to
<literal>enp0s25
</literal>.
</para>
3450 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
3455 MACVTAP=macvtap-test
3460 <title>A Xfrm interface with physical underlying device.
</title>
3462 <programlisting># /etc/systemd/network/
27-xfrm.netdev
3467 InterfaceId=
7</programlisting>
3469 <programlisting># /etc/systemd/network/
27-eth0.network
3474 Xfrm=xfrm0
</programlisting>
3476 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
3477 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
3478 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
3484 <title>See Also
</title>
3486 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
3487 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
3488 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3489 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3490 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
projects / thirdparty / systemd.git / blob