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'
>
9 <title>systemd.network
</title>
10 <productname>systemd
</productname>
14 <refentrytitle>systemd.network
</refentrytitle>
15 <manvolnum>5</manvolnum>
19 <refname>systemd.network
</refname>
20 <refpurpose>Network configuration
</refpurpose>
24 <para><filename><replaceable>network
</replaceable>.network
</filename></para>
28 <title>Description
</title>
30 <para>Network setup is performed by
31 <citerefentry><refentrytitle>systemd-networkd
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
34 <para>The main network file must have the extension
<filename>.network
</filename>; other
35 extensions are ignored. Networks are applied to links whenever the links appear.
</para>
37 <para>The
<filename>.network
</filename> files are read from the files located in the system network
38 directories
<filename>/usr/lib/systemd/network
</filename> and
39 <filename>/usr/local/lib/systemd/network
</filename>, the volatile runtime network directory
40 <filename>/run/systemd/network
</filename> and the local administration network directory
41 <filename>/etc/systemd/network
</filename>. All configuration files are collectively sorted and processed
42 in lexical order, regardless of the directories in which they live. However, files with identical
43 filenames replace each other. Files in
<filename>/etc
</filename> have the highest priority, files in
44 <filename>/run
</filename> take precedence over files with the same name under
45 <filename>/usr
</filename>. This can be used to override a system-supplied configuration file with a local
46 file if needed. As a special case, an empty file (file size
0) or symlink with the same name pointing to
47 <filename>/dev/null
</filename> disables the configuration file entirely (it is
"masked").
</para>
49 <para>Along with the network file
<filename>foo.network
</filename>, a
"drop-in" directory
50 <filename>foo.network.d/
</filename> may exist. All files with the suffix
51 <literal>.conf
</literal> from this directory will be parsed after the file itself is
52 parsed. This is useful to alter or add configuration settings, without having to modify the main
53 configuration file. Each drop-in file must have appropriate section headers.
</para>
55 <para>In addition to
<filename>/etc/systemd/network
</filename>, drop-in
<literal>.d
</literal>
56 directories can be placed in
<filename>/usr/lib/systemd/network
</filename> or
57 <filename>/run/systemd/network
</filename> directories. Drop-in files in
58 <filename>/etc
</filename> take precedence over those in
<filename>/run
</filename> which in turn
59 take precedence over those in
<filename>/usr/lib
</filename>. Drop-in files under any of these
60 directories take precedence over the main netdev file wherever located.
</para>
62 <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6
63 nor IPv6LL enabled, shall be considered to have no IPv6 support. IPv6 will be automatically
64 disabled for that interface by writing
"1" to
65 <filename>/proc/sys/net/ipv6/conf/
<replaceable>ifname
</replaceable>/disable_ipv6
</filename>.
70 <title>[Match] Section Options
</title>
72 <para>The network file contains a
<literal>[Match]
</literal>
73 section, which determines if a given network file may be applied
74 to a given device; and a
<literal>[Network]
</literal> section
75 specifying how the device should be configured. The first (in
76 lexical order) of the network files that matches a given device
77 is applied, all later files are ignored, even if they match as
80 <para>A network file is said to match a network interface if all matches specified by the
81 <literal>[Match]
</literal> section are satisfied. When a network file does not contain valid
82 settings in
<literal>[Match]
</literal> section, then the file will match all interfaces and
83 <command>systemd-networkd
</command> warns about that. Hint: to avoid the warning and to make it
84 clear that all interfaces shall be matched, add the following:
85 <programlisting>Name=*
</programlisting>
86 The following keys are accepted:
</para>
88 <variablelist class='network-directives'
>
90 <term><varname>MACAddress=
</varname></term>
92 <para>A whitespace-separated list of hardware addresses. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example below.
93 This option may appear more than one, in which case the lists are merged. If the empty string is assigned to this option, the list
94 of hardware addresses defined prior to this is reset.
</para>
97 <programlisting>MACAddress=
01:
23:
45:
67:
89:ab
00-
11-
22-
33-
44-
55 AABB.CCDD.EEFF
</programlisting></para>
101 <term><varname>Path=
</varname></term>
103 <para>A whitespace-separated list of shell-style globs
104 matching the persistent path, as exposed by the udev
105 property
<literal>ID_PATH
</literal>. If the list is
106 prefixed with a
"!", the test is inverted; i.e. it is
107 true when
<literal>ID_PATH
</literal> does not match any
108 item in the list.
</para>
112 <term><varname>Driver=
</varname></term>
114 <para>A whitespace-separated list of shell-style globs
115 matching the driver currently bound to the device, as
116 exposed by the udev property
<literal>DRIVER
</literal>
117 of its parent device, or if that is not set the driver
118 as exposed by
<literal>ethtool -i
</literal> of the
119 device itself. If the list is prefixed with a
"!", the
120 test is inverted.
</para>
124 <term><varname>Type=
</varname></term>
126 <para>A whitespace-separated list of shell-style globs
127 matching the device type, as exposed by the udev property
128 <literal>DEVTYPE
</literal>. If the list is prefixed with
129 a
"!", the test is inverted.
</para>
133 <term><varname>Name=
</varname></term>
135 <para>A whitespace-separated list of shell-style globs
136 matching the device name, as exposed by the udev property
137 <literal>INTERFACE
</literal>. If the list is prefixed
138 with a
"!", the test is inverted.
</para>
142 <term><varname>Host=
</varname></term>
144 <para>Matches against the hostname or machine ID of the host. See
145 <literal>ConditionHost=
</literal> in
146 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
147 for details. When prefixed with an exclamation mark (
<literal>!
</literal>), the result is negated.
148 If an empty string is assigned, then previously assigned value is cleared.
153 <term><varname>Virtualization=
</varname></term>
155 <para>Checks whether the system is executed in a virtualized environment and optionally test
156 whether it is a specific implementation. See
<literal>ConditionVirtualization=
</literal> in
157 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
158 for details. When prefixed with an exclamation mark (
<literal>!
</literal>), the result is negated.
159 If an empty string is assigned, then previously assigned value is cleared.
164 <term><varname>KernelCommandLine=
</varname></term>
166 <para>Checks whether a specific kernel command line option is set. See
167 <literal>ConditionKernelCommandLine=
</literal> in
168 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
169 for details. When prefixed with an exclamation mark (
<literal>!
</literal>), the result is negated.
170 If an empty string is assigned, then previously assigned value is cleared.
175 <term><varname>KernelVersion=
</varname></term>
177 <para>Checks whether the kernel version (as reported by
<command>uname -r
</command>) matches a
178 certain expression. See
<literal>ConditionKernelVersion=
</literal> in
179 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
180 for details. When prefixed with an exclamation mark (
<literal>!
</literal>), the result is negated.
181 If an empty string is assigned, then previously assigned value is cleared.
186 <term><varname>Architecture=
</varname></term>
188 <para>Checks whether the system is running on a specific architecture. See
189 <literal>ConditionArchitecture=
</literal> in
190 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
191 for details. When prefixed with an exclamation mark (
<literal>!
</literal>), the result is negated.
192 If an empty string is assigned, then previously assigned value is cleared.
201 <title>[Link] Section Options
</title>
203 <para> The
<literal>[Link]
</literal> section accepts the following keys:
</para>
205 <variablelist class='network-directives'
>
207 <term><varname>MACAddress=
</varname></term>
209 <para>The hardware address to set for the device.
</para>
213 <term><varname>MTUBytes=
</varname></term>
215 <para>The maximum transmission unit in bytes to set for the
216 device. The usual suffixes K, M, G, are supported and are
217 understood to the base of
1024.
</para>
218 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
219 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
223 <term><varname>ARP=
</varname></term>
225 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
226 for this interface is enabled. When unset, the kernel's default will be used.
</para>
227 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
228 interfaces atop a single lower-level physical interface, which will then only serve as a
229 link/
"bridge" device aggregating traffic to the same physical link and not participate in
230 the network otherwise.
</para>
234 <term><varname>Multicast=
</varname></term>
236 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled.
</para>
240 <term><varname>AllMulticast=
</varname></term>
242 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the network.
243 This happens when multicast routing is enabled.
</para>
247 <term><varname>Unmanaged=
</varname></term>
249 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are
250 made to bring up or configure matching links, equivalent to
251 when there are no matching network files. Defaults to
252 <literal>no
</literal>.
</para>
253 <para>This is useful for preventing later matching network
254 files from interfering with certain interfaces that are fully
255 controlled by other applications.
</para>
259 <term><varname>RequiredForOnline=
</varname></term>
261 <para>Takes a boolean or operational state. Please see
262 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
263 for possible operational states. When
<literal>yes
</literal>, the network is deemed required when
264 determining whether the system is online when running
265 <command>systemd-networkd-wait-online
</command>. When
<literal>no
</literal>, the network is ignored
266 when checking for online state. When an operational state is set,
<literal>yes
</literal> is implied,
267 and this controls the operational state required for the network interface to be considered online.
268 Defaults to
<literal>yes
</literal>.
</para>
270 <para>The network will be brought up normally in all cases, but in
271 the event that there is no address being assigned by DHCP or the
272 cable is not plugged in, the link will simply remain offline and be
273 skipped automatically by
<command>systemd-networkd-wait-online
</command>
274 if
<literal>RequiredForOnline=no
</literal>.
</para>
281 <title>[Network] Section Options
</title>
283 <para>The
<literal>[Network]
</literal> section accepts the following keys:
</para>
285 <variablelist class='network-directives'
>
287 <term><varname>Description=
</varname></term>
289 <para>A description of the device. This is only used for
290 presentation purposes.
</para>
294 <term><varname>DHCP=
</varname></term>
296 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
297 <literal>yes
</literal>,
<literal>no
</literal>,
298 <literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults
299 to
<literal>no
</literal>.
</para>
301 <para>Note that DHCPv6 will by default be triggered by Router
302 Advertisement, if that is enabled, regardless of this parameter.
303 By enabling DHCPv6 support explicitly, the DHCPv6 client will
304 be started regardless of the presence of routers on the link,
305 or what flags the routers pass. See
306 <literal>IPv6AcceptRA=
</literal>.
</para>
308 <para>Furthermore, note that by default the domain name
309 specified through DHCP is not used for name resolution.
310 See option
<option>UseDomains=
</option> below.
</para>
312 <para>See the
<literal>[DHCP]
</literal> section below for further configuration options for the DHCP client
317 <term><varname>DHCPServer=
</varname></term>
319 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started. Defaults
320 to
<literal>no
</literal>. Further settings for the DHCP
321 server may be set in the
<literal>[DHCPServer]
</literal>
322 section described below.
</para>
326 <term><varname>LinkLocalAddressing=
</varname></term>
328 <para>Enables link-local address autoconfiguration. Accepts
<literal>yes
</literal>,
329 <literal>no
</literal>,
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
330 <literal>fallback
</literal>, or
<literal>ipv4-fallback
</literal>. If
331 <literal>fallback
</literal> or
<literal>ipv4-fallback
</literal> is specified, then an IPv4
332 link-local address is configured only when DHCPv4 fails. If
<literal>fallback
</literal>,
333 an IPv6 link-local address is always configured, and if
<literal>ipv4-fallback
</literal>,
334 the address is not configured. Note that, the fallback mechanism works only when DHCPv4
335 client is enabled, that is, it requires
<literal>DHCP=yes
</literal> or
336 <literal>DHCP=ipv4
</literal>. If
<varname>Bridge=
</varname> is set, defaults to
337 <literal>no
</literal>, and if not, defaults to
<literal>ipv6
</literal>.
342 <term><varname>IPv4LLRoute=
</varname></term>
344 <para>Takes a boolean. If set to true, sets up the route needed for
345 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
351 <term><varname>IPv6Token=
</varname></term>
353 <para>An IPv6 address with the top
64 bits unset. When set, indicates the
354 64-bit interface part of SLAAC IPv6 addresses for this link. Note that
355 the token is only ever used for SLAAC, and not for DHCPv6 addresses, even
356 in the case DHCP is requested by router advertisement. By default, the
357 token is autogenerated.
</para>
361 <term><varname>LLMNR=
</varname></term>
363 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
365 url=
"https://tools.ietf.org/html/rfc4795">Link-Local
366 Multicast Name Resolution
</ulink> on the link. When set to
367 <literal>resolve
</literal>, only resolution is enabled,
368 but not host registration and announcement. Defaults to
369 true. This setting is read by
370 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
374 <term><varname>MulticastDNS=
</varname></term>
376 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
378 url=
"https://tools.ietf.org/html/rfc6762">Multicast
379 DNS
</ulink> support on the link. When set to
380 <literal>resolve
</literal>, only resolution is enabled,
381 but not host or service registration and
382 announcement. Defaults to false. This setting is read by
383 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
387 <term><varname>DNSOverTLS=
</varname></term>
390 <literal>opportunistic
</literal>. When set to
<literal>opportunistic
</literal>, enables
392 url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink>
393 support on the link. This option defines a
394 per-interface setting for
395 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
396 global
<varname>DNSOverTLS=
</varname> option. Defaults to
397 false. This setting is read by
398 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
402 <term><varname>DNSSEC=
</varname></term>
404 <para>Takes a boolean. or
405 <literal>allow-downgrade
</literal>. When true, enables
407 url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink>
408 DNS validation support on the link. When set to
409 <literal>allow-downgrade
</literal>, compatibility with
410 non-DNSSEC capable networks is increased, by automatically
411 turning off DNSSEC in this case. This option defines a
412 per-interface setting for
413 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
414 global
<varname>DNSSEC=
</varname> option. Defaults to
415 false. This setting is read by
416 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
420 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
421 <listitem><para>A space-separated list of DNSSEC negative
422 trust anchor domains. If specified and DNSSEC is enabled,
423 look-ups done via the interface's DNS server will be subject
424 to the list of negative trust anchors, and not require
425 authentication for the specified domains, or anything below
426 it. Use this to disable DNSSEC authentication for specific
427 private domains, that cannot be proven valid using the
428 Internet DNS hierarchy. Defaults to the empty list. This
430 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
434 <term><varname>LLDP=
</varname></term>
436 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
437 implemented on professional routers and bridges which announces which physical port a system is connected
438 to, as well as other related data. Accepts a boolean or the special value
439 <literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
440 neighbors maintained. If
<literal>routers-only
</literal> is set only LLDP data of various types of routers
441 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
442 others). If false, LLDP reception is disabled. Defaults to
<literal>routers-only
</literal>. Use
443 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
444 collected neighbor data. LLDP is only available on Ethernet links. See
<varname>EmitLLDP=
</varname> below
445 for enabling LLDP packet emission from the local system.
450 <term><varname>EmitLLDP=
</varname></term>
452 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
453 <literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
454 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
455 a short LLDP packet with information about the local system is sent out in regular intervals on the
456 link. The LLDP packet will contain information about the local host name, the local machine ID (as stored
457 in
<citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
458 local interface name, as well as the pretty hostname of the system (as set in
459 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
460 emission is only available on Ethernet links. Note that this setting passes data suitable for
461 identification of host to the network and should thus not be enabled on untrusted networks, where such
462 identification data should not be made available. Use this option to permit other systems to identify on
463 which interfaces they are connected to this system. The three special values control propagation of the
464 LLDP packets. The
<literal>nearest-bridge
</literal> setting permits propagation only to the nearest
465 connected bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays, but
466 not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until a customer bridge
467 is reached. For details about these concepts, see
<ulink
468 url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>. Note that
469 configuring this setting to true is equivalent to
<literal>nearest-bridge
</literal>, the recommended and
470 most restricted level of propagation. See
<varname>LLDP=
</varname> above for an option to enable LLDP
475 <term><varname>BindCarrier=
</varname></term>
477 <para>A link name or a list of link names. When set, controls the behavior of the current
478 link. When all links in the list are in an operational down state, the current link is brought
479 down. When at least one link has carrier, the current interface is brought up.
484 <term><varname>Address=
</varname></term>
486 <para>A static IPv4 or IPv6 address and its prefix length,
487 separated by a
<literal>/
</literal> character. Specify
488 this key more than once to configure several addresses.
489 The format of the address must be as described in
490 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
491 This is a short-hand for an [Address] section only
492 containing an Address key (see below). This option may be
493 specified more than once.
496 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
497 (for IPv6), a new address range of the requested size is automatically allocated from a
498 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
499 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
500 all known network configuration files to avoid address range conflicts. The default system-wide
501 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.
502 This functionality is useful to manage a large number of dynamically created network interfaces
503 with the same network configuration and automatic address range assignment.
</para>
508 <term><varname>Gateway=
</varname></term>
510 <para>The gateway address, which must be in the format
512 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
513 This is a short-hand for a [Route] section only containing
514 a Gateway key. This option may be specified more than
519 <term><varname>DNS=
</varname></term>
521 <para>A DNS server address, which must be in the format
523 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
524 This option may be specified more than once. This setting is read by
525 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
529 <term><varname>Domains=
</varname></term>
531 <para>A list of domains which should be resolved using the DNS servers on this link. Each item in the list
532 should be a domain name, optionally prefixed with a tilde (
<literal>~
</literal>). The domains with the
533 prefix are called
"routing-only domains". The domains without the prefix are called
"search domains" and
534 are first used as search suffixes for extending single-label host names (host names containing no dots) to
535 become fully qualified domain names (FQDNs). If a single-label host name is resolved on this interface,
536 each of the specified search domains are appended to it in turn, converting it into a fully qualified
537 domain name, until one of them may be successfully resolved.
</para>
539 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for host names
540 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
541 the DNS servers configured for this interface. The domain routing logic is particularly useful on
542 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
544 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
545 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
546 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
547 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
548 if a link on which they are connected is available.
</para>
550 <para>This setting is read by
551 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
552 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
553 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
554 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
555 name servers limited to a specific link.
</para>
559 <term><varname>DNSDefaultRoute=
</varname></term>
561 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
562 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
563 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
564 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
565 queries not matching any link's configured domains will be routed to this link if it has no routing-only
566 domains configured.
</para>
570 <term><varname>NTP=
</varname></term>
572 <para>An NTP server address. This option may be specified more than once. This setting is read by
573 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
577 <term><varname>IPForward=
</varname></term>
578 <listitem><para>Configures IP packet forwarding for the
579 system. If enabled, incoming packets on any network
580 interface will be forwarded to any other interfaces
581 according to the routing table. Takes a boolean,
582 or the values
<literal>ipv4
</literal> or
583 <literal>ipv6
</literal>, which only enable IP packet
584 forwarding for the specified address family. This controls
585 the
<filename>net.ipv4.ip_forward
</filename> and
586 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
587 options of the network interface (see
<ulink
588 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
589 for details about sysctl options). Defaults to
590 <literal>no
</literal>.
</para>
592 <para>Note: this setting controls a global kernel option,
593 and does so one way only: if a network that has this setting
594 enabled is set up the global setting is turned on. However,
595 it is never turned off again, even after all networks with
596 this setting enabled are shut down again.
</para>
598 <para>To allow IP packet forwarding only between specific
599 network interfaces use a firewall.
</para>
603 <term><varname>IPMasquerade=
</varname></term>
604 <listitem><para>Configures IP masquerading for the network
605 interface. If enabled, packets forwarded from the network
606 interface will be appear as coming from the local host.
607 Takes a boolean argument. Implies
608 <varname>IPForward=ipv4
</varname>. Defaults to
609 <literal>no
</literal>.
</para></listitem>
612 <term><varname>IPv6PrivacyExtensions=
</varname></term>
613 <listitem><para>Configures use of stateless temporary
614 addresses that change over time (see
<ulink
615 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
616 Privacy Extensions for Stateless Address Autoconfiguration
617 in IPv6). Takes a boolean or the special values
618 <literal>prefer-public
</literal> and
619 <literal>kernel
</literal>. When true, enables the privacy
620 extensions and prefers temporary addresses over public
621 addresses. When
<literal>prefer-public
</literal>, enables the
622 privacy extensions, but prefers public addresses over
623 temporary addresses. When false, the privacy extensions
624 remain disabled. When
<literal>kernel
</literal>, the kernel's
625 default setting will be left in place. Defaults to
626 <literal>no
</literal>.
</para></listitem>
629 <term><varname>IPv6AcceptRA=
</varname></term>
630 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the interface.
631 If true, RAs are accepted; if false, RAs are ignored, independently of the local forwarding state.
632 If unset, the kernel's default is used, and RAs are accepted only when local forwarding
633 is disabled for that interface. When RAs are accepted, they may trigger the start of the DHCPv6 client if
634 the relevant flags are set in the RA data, or if no routers are found on the link.
</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 if this option is enabled a userspace implementation of the IPv6 RA protocol is
645 used, and the kernel's own implementation remains disabled, since `networkd` needs to know all
646 details supplied in the advertisements, and these are not available from the kernel if the kernel's
647 own implementation is used.
</para>
651 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
652 <listitem><para>Configures the amount of IPv6 Duplicate
653 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
657 <term><varname>IPv6HopLimit=
</varname></term>
658 <listitem><para>Configures IPv6 Hop Limit. For each router that
659 forwards the packet, the hop limit is decremented by
1. When the
660 hop limit field reaches zero, the packet is discarded.
661 When unset, the kernel's default will be used.
665 <term><varname>IPv4ProxyARP=
</varname></term>
666 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
667 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
668 the router accepts responsibility for routing packets to the
"real" destination. (see
<ulink
669 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
670 When unset, the kernel's default will be used.
674 <term><varname>IPv6ProxyNDP=
</varname></term>
675 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
676 Protocol) is a technique for IPv6 to allow routing of addresses to a different
677 destination when peers expect them to be present on a certain physical link.
678 In this case a router answers Neighbour Advertisement messages intended for
679 another machine by offering its own MAC address as destination.
680 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
681 Advertisement messages for addresses in the IPv6 neighbor proxy table,
682 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
683 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
684 interface depending on this option.
685 When unset, the kernel's default will be used.
689 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
690 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
691 proxied. This option may be specified more than once. systemd-networkd will add the
692 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
693 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
694 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
698 <term><varname>IPv6PrefixDelegation=
</varname></term>
699 <listitem><para>Whether to enable or disable Router Advertisement sending on a link.
700 Allowed values are
<literal>static
</literal> which distributes prefixes as defined in
701 the
<literal>[IPv6PrefixDelegation]
</literal> and any
<literal>[IPv6Prefix]
</literal>
702 sections,
<literal>dhcpv6
</literal> which requests prefixes using a DHCPv6 client
703 configured for another link and any values configured in the
704 <literal>[IPv6PrefixDelegation]
</literal> section while ignoring all static prefix
705 configuration sections,
<literal>yes
</literal> which uses both static configuration
706 and DHCPv6, and
<literal>false
</literal> which turns off IPv6 prefix delegation
707 altogether. Defaults to
<literal>false
</literal>. See the
708 <literal>[IPv6PrefixDelegation]
</literal> and the
<literal>[IPv6Prefix]
</literal>
709 sections for more configuration options.
713 <term><varname>IPv6MTUBytes=
</varname></term>
714 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
715 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
719 <term><varname>Bridge=
</varname></term>
721 <para>The name of the bridge to add the link to. See
722 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
727 <term><varname>Bond=
</varname></term>
729 <para>The name of the bond to add the link to. See
730 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
735 <term><varname>VRF=
</varname></term>
737 <para>The name of the VRF to add the link to. See
738 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
743 <term><varname>VLAN=
</varname></term>
745 <para>The name of a VLAN to create on the link. See
746 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
747 This option may be specified more than once.
</para>
751 <term><varname>IPVLAN=
</varname></term>
753 <para>The name of a IPVLAN to create on the link. See
754 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
755 This option may be specified more than once.
</para>
759 <term><varname>MACVLAN=
</varname></term>
761 <para>The name of a MACVLAN to create on the link. See
762 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
763 This option may be specified more than once.
</para>
767 <term><varname>VXLAN=
</varname></term>
769 <para>The name of a VXLAN to create on the link. See
770 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
771 This option may be specified more than once.
</para>
775 <term><varname>Tunnel=
</varname></term>
777 <para>The name of a Tunnel to create on the link. See
778 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
779 This option may be specified more than once.
</para>
783 <term><varname>MACsec=
</varname></term>
785 <para>The name of a MACsec device to create on the link. See
786 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
787 This option may be specified more than once.
</para>
791 <term><varname>ActiveSlave=
</varname></term>
793 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
794 option is only valid for following modes:
795 <literal>active-backup
</literal>,
796 <literal>balance-alb
</literal> and
797 <literal>balance-tlb
</literal>. Defaults to false.
802 <term><varname>PrimarySlave=
</varname></term>
804 <para>Takes a boolean. Specifies which slave is the primary device. The specified
805 device will always be the active slave while it is available. Only when the
806 primary is off-line will alternate devices be used. This is useful when
807 one slave is preferred over another, e.g. when one slave has higher throughput
808 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
810 <literal>active-backup
</literal>,
811 <literal>balance-alb
</literal> and
812 <literal>balance-tlb
</literal>. Defaults to false.
817 <term><varname>ConfigureWithoutCarrier=
</varname></term>
819 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
825 <term><varname>IgnoreCarrierLoss=
</varname></term>
827 <para>A boolean. Allows networkd to retain both the static and dynamic configuration of the
828 interface even if its carrier is lost. Defaults to false.
838 <title>[Address] Section Options
</title>
840 <para>An
<literal>[Address]
</literal> section accepts the
841 following keys. Specify several
<literal>[Address]
</literal>
842 sections to configure several addresses.
</para>
844 <variablelist class='network-directives'
>
846 <term><varname>Address=
</varname></term>
848 <para>As in the
<literal>[Network]
</literal> section. This key is mandatory. Each
849 <literal>[Address]
</literal> section can contain one
<varname>Address=
</varname> setting.
</para>
853 <term><varname>Peer=
</varname></term>
855 <para>The peer address in a point-to-point connection.
856 Accepts the same format as the
<varname>Address=
</varname>
861 <term><varname>Broadcast=
</varname></term>
863 <para>The broadcast address, which must be in the format
865 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
866 This key only applies to IPv4 addresses. If it is not
867 given, it is derived from the
<varname>Address=
</varname>
872 <term><varname>Label=
</varname></term>
874 <para>An address label.
</para>
878 <term><varname>PreferredLifetime=
</varname></term>
880 <para>Allows the default
"preferred lifetime" of the address to be overridden.
881 Only three settings are accepted:
<literal>forever
</literal> or
<literal>infinity
</literal>
882 which is the default and means that the address never expires, and
<literal>0</literal> which means
883 that the address is considered immediately
"expired" and will not be used,
884 unless explicitly requested. A setting of PreferredLifetime=
0 is useful for
885 addresses which are added to be used only by a specific application,
886 which is then configured to use them explicitly.
</para>
890 <term><varname>Scope=
</varname></term>
892 <para>The scope of the address, which can be
<literal>global
</literal>,
893 <literal>link
</literal> or
<literal>host
</literal> or an unsigned integer ranges
0 to
255.
894 Defaults to
<literal>global
</literal>.
</para>
898 <term><varname>HomeAddress=
</varname></term>
900 <para>Takes a boolean. Designates this address the
"home address" as defined in
901 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
902 Supported only on IPv6. Defaults to false.
</para>
906 <term><varname>DuplicateAddressDetection=
</varname></term>
908 <para>Takes a boolean. Do not perform Duplicate Address Detection
909 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink> when adding this address.
910 Supported only on IPv6. Defaults to false.
</para>
914 <term><varname>ManageTemporaryAddress=
</varname></term>
916 <para>Takes a boolean. If true the kernel manage temporary addresses created
917 from this one as template on behalf of Privacy Extensions
918 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
919 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
920 The given address needs to have a prefix length of
64. This flag allows to use privacy
921 extensions in a manually configured network, just like if stateless auto-configuration
922 was active. Defaults to false.
</para>
926 <term><varname>PrefixRoute=
</varname></term>
928 <para>Takes a boolean. When adding or modifying an IPv6 address, the userspace
929 application needs a way to suppress adding a prefix route. This is for example relevant
930 together with IFA_F_MANAGERTEMPADDR, where userspace creates autoconf generated addresses,
931 but depending on on-link, no route for the prefix should be added. Defaults to false.
</para>
935 <term><varname>AutoJoin=
</varname></term>
937 <para>Takes a boolean. Joining multicast group on ethernet level via
938 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
939 IGMP snooping since the switch would not replicate multicast packets on ports that did not
940 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
941 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
942 that enables then to do the required join. By extending ip address command with option
943 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
944 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
945 Defaults to
<literal>no
</literal>.
</para>
952 <title>[Neighbor] Section Options
</title>
953 <para>A
<literal>[Neighbor]
</literal> section accepts the
954 following keys. The neighbor section adds a permanent, static
955 entry to the neighbor table (IPv6) or ARP table (IPv4) for
956 the given hardware address on the links matched for the network.
957 Specify several
<literal>[Neighbor]
</literal> sections to configure
958 several static neighbors.
</para>
960 <variablelist class='network-directives'
>
962 <term><varname>Address=
</varname></term>
964 <para>The IP address of the neighbor.
</para>
968 <term><varname>MACAddress=
</varname></term>
970 <para>The hardware address of the neighbor.
</para>
977 <title>[IPv6AddressLabel] Section Options
</title>
979 <para>An
<literal>[IPv6AddressLabel]
</literal> section accepts the
980 following keys. Specify several
<literal>[IPv6AddressLabel]
</literal>
981 sections to configure several address labels. IPv6 address labels are
982 used for address selection. See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>.
983 Precedence is managed by userspace, and only the label itself is stored in the kernel
</para>
985 <variablelist class='network-directives'
>
987 <term><varname>Label=
</varname></term>
989 <para> The label for the prefix (an unsigned integer) ranges
0 to
4294967294.
990 0xffffffff is reserved. This key is mandatory.
</para>
994 <term><varname>Prefix=
</varname></term>
996 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
997 This key is mandatory.
</para>
1004 <title>[RoutingPolicyRule] Section Options
</title>
1006 <para>An
<literal>[RoutingPolicyRule]
</literal> section accepts the
1007 following keys. Specify several
<literal>[RoutingPolicyRule]
</literal>
1008 sections to configure several rules.
</para>
1010 <variablelist class='network-directives'
>
1012 <term><varname>TypeOfService=
</varname></term>
1014 <para>Specifies the type of service to match a number between
0 to
255.
</para>
1018 <term><varname>From=
</varname></term>
1020 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1024 <term><varname>To=
</varname></term>
1026 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1030 <term><varname>FirewallMark=
</varname></term>
1032 <para>Specifies the iptables firewall mark value to match (a number between
1 and
4294967295).
</para>
1036 <term><varname>Table=
</varname></term>
1038 <para>Specifies the routing table identifier to lookup if the rule
1039 selector matches. The table identifier for a route (a number between
1 and
4294967295).
</para>
1043 <term><varname>Priority=
</varname></term>
1045 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1046 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1050 <term><varname>IncomingInterface=
</varname></term>
1052 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1056 <term><varname>OutgoingInterface=
</varname></term>
1058 <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>
1062 <term><varname>SourcePort=
</varname></term>
1064 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1065 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1069 <term><varname>DestinationPort=
</varname></term>
1071 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1072 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1076 <term><varname>IPProtocol=
</varname></term>
1078 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1079 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1080 <literal>17</literal> for
<literal>udp
</literal>.
1081 Defaults to unset.
</para>
1085 <term><varname>InvertRule=
</varname></term>
1087 <para>A boolean. Specifies whether the rule to be inverted. Defaults to false.
</para>
1094 <title>[Route] Section Options
</title>
1095 <para>The
<literal>[Route]
</literal> section accepts the
1096 following keys. Specify several
<literal>[Route]
</literal>
1097 sections to configure several routes.
</para>
1099 <variablelist class='network-directives'
>
1101 <term><varname>Gateway=
</varname></term>
1103 <para>As in the
<literal>[Network]
</literal> section.
</para>
1107 <term><varname>GatewayOnLink=
</varname></term>
1109 <para>Takes a boolean. If set to true, the kernel does not have
1110 to check if the gateway is reachable directly by the current machine (i.e., the kernel does
1111 not need to check if the gateway is attached to the local network), so that we can insert the
1112 route in the kernel table without it being complained about. Defaults to
<literal>no
</literal>.
1117 <term><varname>Destination=
</varname></term>
1119 <para>The destination prefix of the route. Possibly
1120 followed by a slash and the prefix length. If omitted, a
1121 full-length host route is assumed.
</para>
1125 <term><varname>Source=
</varname></term>
1127 <para>The source prefix of the route. Possibly followed by
1128 a slash and the prefix length. If omitted, a full-length
1129 host route is assumed.
</para>
1133 <term><varname>Metric=
</varname></term>
1135 <para>The metric of the route (an unsigned integer).
</para>
1139 <term><varname>IPv6Preference=
</varname></term>
1141 <para>Specifies the route preference as defined in
<ulink
1142 url=
"https://tools.ietf.org/html/rfc4191">RFC4191
</ulink> for Router Discovery messages.
1143 Which can be one of
<literal>low
</literal> the route has a lowest priority,
1144 <literal>medium
</literal> the route has a default priority or
1145 <literal>high
</literal> the route has a highest priority.
</para>
1149 <term><varname>Scope=
</varname></term>
1151 <para>The scope of the route, which can be
<literal>global
</literal>,
1152 <literal>link
</literal> or
<literal>host
</literal>. Defaults to
1153 <literal>global
</literal>.
</para>
1157 <term><varname>PreferredSource=
</varname></term>
1159 <para>The preferred source address of the route. The address
1160 must be in the format described in
1161 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1165 <term><varname>Table=
<replaceable>num
</replaceable></varname></term>
1167 <para>The table identifier for the route (a number between
1 and
4294967295, or
0 to unset).
1168 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1173 <term><varname>Protocol=
</varname></term>
1175 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1176 <literal>kernel
</literal>,
<literal>boot
</literal> and
<literal>static
</literal>. Defaults to
1177 <literal>static
</literal>.
1182 <term><varname>Type=
</varname></term>
1184 <para>Specifies the type for the route. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1185 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1186 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1187 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1188 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1189 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1190 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1195 <term><varname>InitialCongestionWindow=
</varname></term>
1197 <para>The TCP initial congestion window is used during the start of a TCP connection. During the start of a TCP
1198 session, when a client requests a resource, the server's initial congestion window determines how many data bytes
1199 will be sent during the initial burst of data. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual
1200 suffixes K, M, G are supported and are understood to the base of
1024. When unset, the kernel's default will be used.
1205 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1207 <para>The TCP initial advertised receive window is the amount of receive data (in bytes) that can initially be buffered at one time
1208 on a connection. The sending host can send only that amount of data before waiting for an acknowledgment and window update
1209 from the receiving host. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual suffixes K, M, G are supported
1210 and are understood to the base of
1024. When unset, the kernel's default will be used.
1215 <term><varname>QuickAck=
</varname></term>
1217 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1222 <term><varname>MTUBytes=
</varname></term>
1224 <para>The maximum transmission unit in bytes to set for the
1225 route. The usual suffixes K, M, G, are supported and are
1226 understood to the base of
1024.
</para>
1227 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1228 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1235 <title>[DHCP] Section Options
</title>
1236 <para>The
<literal>[DHCP]
</literal> section configures the
1237 DHCPv4 and DHCP6 client, if it is enabled with the
1238 <varname>DHCP=
</varname> setting described above:
</para>
1240 <variablelist class='network-directives'
>
1242 <term><varname>UseDNS=
</varname></term>
1244 <para>When true (the default), the DNS servers received
1245 from the DHCP server will be used and take precedence over
1246 any statically configured ones.
</para>
1248 <para>This corresponds to the
<option>nameserver
</option>
1249 option in
<citerefentry
1250 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1254 <term><varname>UseNTP=
</varname></term>
1256 <para>When true (the default), the NTP servers received
1257 from the DHCP server will be used by systemd-timesyncd
1258 and take precedence over any statically configured ones.
</para>
1262 <term><varname>UseMTU=
</varname></term>
1264 <para>When true, the interface maximum transmission unit
1265 from the DHCP server will be used on the current link.
1266 If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
1267 Defaults to false.
</para>
1271 <term><varname>Anonymize=
</varname></term>
1273 <para>Takes a boolean. When true, the options sent to the DHCP server will
1274 follow the
<ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink>
1275 (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying information.
1276 Defaults to false.
</para>
1278 <para>This option should only be set to true when
1279 <varname>MACAddressPolicy=
</varname> is set to
<literal>random
</literal>
1281 project='man-pages'
><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
1283 <para>Note that this configuration will overwrite others.
1284 In concrete, the following variables will be ignored:
1285 <varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1286 <varname>UseRoutes=
</varname>,
<varname>SendHostname=
</varname>,
1287 <varname>UseMTU=
</varname>,
<varname>VendorClassIdentifier=
</varname>,
1288 <varname>UseTimezone=
</varname>.
</para>
1290 <para>With this option enabled DHCP requests will mimic those generated by Microsoft Windows, in
1291 order to reduce the ability to fingerprint and recognize installations. This means DHCP request
1292 sizes will grow and lease data will be more comprehensive than normally, though most of the
1293 requested data is not actually used.
</para>
1297 <term><varname>SendHostname=
</varname></term>
1299 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1300 Note that the machine's hostname must consist only of
7-bit ASCII lower-case characters and
1301 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1302 sent even if this is set to true.
</para>
1306 <term><varname>UseHostname=
</varname></term>
1308 <para>When true (the default), the hostname received from
1309 the DHCP server will be set as the transient hostname of the system.
1314 <term><varname>Hostname=
</varname></term>
1316 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1317 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1318 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1322 <term><varname>UseDomains=
</varname></term>
1324 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1325 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1326 the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name received from
1327 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1328 the
<option>Domains=
</option> setting when the argument is prefixed with
<literal>~
</literal>. Defaults to
1331 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1332 of all host names, in particular of single-label names. It is generally safer to use the supplied domain
1333 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1334 single-label names.
</para>
1336 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1337 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1341 <term><varname>UseRoutes=
</varname></term>
1343 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1344 routing table with a metric of
1024, and a scope of
"global",
"link" or
"host", depending on the route's
1345 destination and gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the
1346 link's own address, the scope will be set to
"host". Otherwise if the gateway is null (a direct route), a
1347 "link" scope will be used. For anything else, scope defaults to
"global".
</para>
1352 <term><varname>UseTimezone=
</varname></term>
1354 <listitem><para>When true, the timezone received from the
1355 DHCP server will be set as timezone of the local
1356 system. Defaults to
<literal>no
</literal>.
</para></listitem>
1360 <term><varname>CriticalConnection=
</varname></term>
1362 <para>When true, the connection will never be torn down
1363 even if the DHCP lease expires. This is contrary to the
1364 DHCP specification, but may be the best choice if, say,
1365 the root filesystem relies on this connection. Defaults to
1371 <term><varname>ClientIdentifier=
</varname></term>
1373 <para>The DHCPv4 client identifier to use. Takes one of
<literal>mac
</literal>,
<literal>duid
</literal> or
<literal>duid-only
</literal>.
1374 If set to
<literal>mac
</literal>, the MAC address of the link is used.
1375 If set to
<literal>duid
</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1376 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.
1377 Defaults to
<literal>duid
</literal>.
</para>
1382 <term><varname>VendorClassIdentifier=
</varname></term>
1384 <para>The vendor class identifier used to identify vendor
1385 type and configuration.
</para>
1390 <term><varname>UserClass=
</varname></term>
1392 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1393 it represents. The information contained in this option is a string that represents the user class of which
1394 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1395 service to classify clients. Takes a whitespace-separated list of strings.
</para>
1400 <term><varname>MaxAttempts=
</varname></term>
1402 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1403 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>.
1404 Note that the time between retries is increased exponentially, so the network will not be
1405 overloaded even if this number is high.
</para>
1410 <term><varname>DUIDType=
</varname></term>
1412 <para>Override the global
<varname>DUIDType
</varname> setting for this network. See
1413 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1414 for a description of possible values.
</para>
1419 <term><varname>DUIDRawData=
</varname></term>
1421 <para>Override the global
<varname>DUIDRawData
</varname> setting for this network. See
1422 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1423 for a description of possible values.
</para>
1428 <term><varname>IAID=
</varname></term>
1430 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned integer.
</para>
1435 <term><varname>RequestBroadcast=
</varname></term>
1437 <para>Request the server to use broadcast messages before
1438 the IP address has been configured. This is necessary for
1439 devices that cannot receive RAW packets, or that cannot
1440 receive packets at all before an IP address has been
1441 configured. On the other hand, this must not be enabled on
1442 networks where broadcasts are filtered out.
</para>
1447 <term><varname>RouteMetric=
</varname></term>
1449 <para>Set the routing metric for routes specified by the
1455 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1457 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1458 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1460 <para>When used in combination with
<varname>VRF=
</varname> the
1461 VRF's routing table is used unless this parameter is specified.
1467 <term><varname>ListenPort=
</varname></term>
1469 <para>Allow setting custom port for the DHCP client to listen on.
</para>
1474 <term><varname>RapidCommit=
</varname></term>
1476 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1477 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1478 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1479 four-method exchange (solicit, advertise, request, and reply). The two-message exchange provides
1480 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1481 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
1482 Defaults to true.
</para>
1487 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
1489 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
1490 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
1491 makes DHCPv6 request network information in a stateless manner using a two-message Information
1492 Request and Information Reply message exchange.
1493 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
1494 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
1495 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
1496 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
1497 By default this option is set to 'false', enable it if no prefixes are delegated when the device
1498 should be acting as a CE router.
</para>
1506 <title>[IPv6AcceptRA] Section Options
</title>
1507 <para>The
<literal>[IPv6AcceptRA]
</literal> section configures the IPv6 Router Advertisement
1508 (RA) client, if it is enabled with the
<varname>IPv6AcceptRA=
</varname> setting described
1511 <variablelist class='network-directives'
>
1513 <term><varname>UseDNS=
</varname></term>
1515 <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
1516 precedence over any statically configured ones.
</para>
1518 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
1519 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1524 <term><varname>UseDomains=
</varname></term>
1526 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1527 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
1528 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
1529 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
1530 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
1531 <literal>~
</literal>. Defaults to false.
</para>
1533 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1534 of all host names, in particular of single-label names. It is generally safer to use the supplied domain
1535 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1536 single-label names.
</para>
1538 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1539 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1544 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1546 <para>The table identifier for the routes received in the Router Advertisement
1547 (a number between
1 and
4294967295, or
0 to unset).
1548 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1554 <term><varname>UseAutonomousPrefix=
</varname></term>
1556 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
1557 precedence over any statically configured ones.
</para>
1562 <term><varname>UseOnLinkPrefix=
</varname></term>
1564 <para>When true (the default), the onlink prefix received in the Router Advertisement will be used and take
1565 precedence over any statically configured ones.
</para>
1573 <title>[DHCPServer] Section Options
</title>
1574 <para>The
<literal>[DHCPServer]
</literal> section contains
1575 settings for the DHCP server, if enabled via the
1576 <varname>DHCPServer=
</varname> option described above:
</para>
1578 <variablelist class='network-directives'
>
1581 <term><varname>PoolOffset=
</varname></term>
1582 <term><varname>PoolSize=
</varname></term>
1584 <listitem><para>Configures the pool of addresses to hand out. The pool
1585 is a contiguous sequence of IP addresses in the subnet configured for
1586 the server address, which does not include the subnet nor the broadcast
1587 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
1588 from the start of subnet, or zero to use the default value.
1589 <varname>PoolSize=
</varname> takes the number of IP addresses in the
1590 pool or zero to use the default value. By default, the pool starts at
1591 the first address after the subnet address and takes up the rest of
1592 the subnet, excluding the broadcast address. If the pool includes
1593 the server address (the default), this is reserved and not handed
1594 out to clients.
</para></listitem>
1598 <term><varname>DefaultLeaseTimeSec=
</varname></term>
1599 <term><varname>MaxLeaseTimeSec=
</varname></term>
1601 <listitem><para>Control the default and maximum DHCP lease
1602 time to pass to clients. These settings take time values in seconds or
1603 another common time unit, depending on the suffix. The default
1604 lease time is used for clients that did not ask for a specific
1605 lease time. If a client asks for a lease time longer than the
1606 maximum lease time, it is automatically shortened to the
1607 specified time. The default lease time defaults to
1h, the
1608 maximum lease time to
12h. Shorter lease times are beneficial
1609 if the configuration data in DHCP leases changes frequently
1610 and clients shall learn the new settings with shorter
1611 latencies. Longer lease times reduce the generated DHCP
1612 network traffic.
</para></listitem>
1616 <term><varname>EmitDNS=
</varname></term>
1617 <term><varname>DNS=
</varname></term>
1619 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1620 to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
1621 The DNS servers to pass to clients may be configured with the
1622 <varname>DNS=
</varname> option, which takes a list of IPv4
1623 addresses. If the
<varname>EmitDNS=
</varname> option is
1624 enabled but no servers configured, the servers are
1625 automatically propagated from an
"uplink" interface that has
1626 appropriate servers set. The
"uplink" interface is determined
1627 by the default route of the system with the highest
1628 priority. Note that this information is acquired at the time
1629 the lease is handed out, and does not take uplink interfaces
1630 into account that acquire DNS or NTP server information at a
1631 later point. DNS server propagation does not take
1632 <filename>/etc/resolv.conf
</filename> into account. Also, note
1633 that the leases are not refreshed if the uplink network
1634 configuration changes. To ensure clients regularly acquire the
1635 most current uplink DNS server information, it is thus
1636 advisable to shorten the DHCP lease time via
1637 <varname>MaxLeaseTimeSec=
</varname> described
1638 above.
</para></listitem>
1642 <term><varname>EmitNTP=
</varname></term>
1643 <term><varname>NTP=
</varname></term>
1645 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1646 <varname>DNS=
</varname> settings described above, these
1647 settings configure whether and what NTP server information
1648 shall be emitted as part of the DHCP lease. The same syntax,
1649 propagation semantics and defaults apply as for
1650 <varname>EmitDNS=
</varname> and
1651 <varname>DNS=
</varname>.
</para></listitem>
1655 <term><varname>EmitRouter=
</varname></term>
1657 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
1658 setting described above, this setting configures whether the
1659 DHCP lease should contain the router option. The same syntax,
1660 propagation semantics and defaults apply as for
1661 <varname>EmitDNS=
</varname>.
</para></listitem>
1665 <term><varname>EmitTimezone=
</varname></term>
1666 <term><varname>Timezone=
</varname></term>
1668 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1669 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
1670 <varname>Timezone=
</varname> setting takes a timezone string
1671 (such as
<literal>Europe/Berlin
</literal> or
1672 <literal>UTC
</literal>) to pass to clients. If no explicit
1673 timezone is set, the system timezone of the local host is
1674 propagated, as determined by the
1675 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
1682 <title>[IPv6PrefixDelegation] Section Options
</title>
1683 <para>The
<literal>[IPv6PrefixDelegation]
</literal> section contains
1684 settings for sending IPv6 Router Advertisements and whether to act as
1685 a router, if enabled via the
<varname>IPv6PrefixDelegation=
</varname>
1686 option described above. IPv6 network prefixes are defined with one or
1687 more
<literal>[IPv6Prefix]
</literal> sections.
</para>
1689 <variablelist class='network-directives'
>
1692 <term><varname>Managed=
</varname></term>
1693 <term><varname>OtherInformation=
</varname></term>
1695 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
1696 addresses on the network link when
<varname>Managed=
</varname>
1697 is set to
<literal>true
</literal> or if only additional network
1698 information can be obtained via DHCPv6 for the network link when
1699 <varname>OtherInformation=
</varname> is set to
1700 <literal>true
</literal>. Both settings default to
1701 <literal>false
</literal>, which means that a DHCPv6 server is not being
1702 used.
</para></listitem>
1706 <term><varname>RouterLifetimeSec=
</varname></term>
1708 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. If set,
1709 this host also announces itself in Router Advertisements as an IPv6
1710 router for the network link. When unset, the host is not acting as a router.
</para>
1715 <term><varname>RouterPreference=
</varname></term>
1717 <listitem><para>Configures IPv6 router preference if
1718 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
1719 <literal>high
</literal>,
<literal>medium
</literal> and
1720 <literal>low
</literal>, with
<literal>normal
</literal> and
1721 <literal>default
</literal> added as synonyms for
1722 <literal>medium
</literal> just to make configuration easier. See
1723 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
1724 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
1728 <term><varname>EmitDNS=
</varname></term>
1729 <term><varname>DNS=
</varname></term>
1731 <listitem><para><varname>DNS=
</varname> specifies a list of recursive
1732 DNS server IPv6 addresses that distributed via Router Advertisement
1733 messages when
<varname>EmitDNS=
</varname> is true. If
<varname>DNS=
1734 </varname> is empty, DNS servers are read from the
1735 <literal>[Network]
</literal> section. If the
1736 <literal>[Network]
</literal> section does not contain any DNS servers
1737 either, DNS servers from the uplink with the highest priority default
1738 route are used. When
<varname>EmitDNS=
</varname> is false, no DNS server
1739 information is sent in Router Advertisement messages.
1740 <varname>EmitDNS=
</varname> defaults to true.
1745 <term><varname>EmitDomains=
</varname></term>
1746 <term><varname>Domains=
</varname></term>
1748 <listitem><para>A list of DNS search domains distributed via Router
1749 Advertisement messages when
<varname>EmitDomains=
</varname> is true. If
1750 <varname>Domains=
</varname> is empty, DNS search domains are read from the
1751 <literal>[Network]
</literal> section. If the
<literal>[Network]
</literal>
1752 section does not contain any DNS search domains either, DNS search
1753 domains from the uplink with the highest priority default route are
1754 used. When
<varname>EmitDomains=
</varname> is false, no DNS search domain
1755 information is sent in Router Advertisement messages.
1756 <varname>EmitDomains=
</varname> defaults to true.
1761 <term><varname>DNSLifetimeSec=
</varname></term>
1763 <listitem><para>Lifetime in seconds for the DNS server addresses listed
1764 in
<varname>DNS=
</varname> and search domains listed in
1765 <varname>Domains=
</varname>.
</para></listitem>
1772 <title>[IPv6Prefix] Section Options
</title>
1773 <para>One or more
<literal>[IPv6Prefix]
</literal> sections contain the IPv6
1774 prefixes that are announced via Router Advertisements. See
1775 <ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink>
1776 for further details.
</para>
1778 <variablelist class='network-directives'
>
1781 <term><varname>AddressAutoconfiguration=
</varname></term>
1782 <term><varname>OnLink=
</varname></term>
1784 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
1785 autoconfigured with this prefix and whether the prefix can be used for
1786 onlink determination. Both settings default to
<literal>true
</literal>
1787 in order to ease configuration.
1792 <term><varname>Prefix=
</varname></term>
1794 <listitem><para>The IPv6 prefix that is to be distributed to hosts.
1795 Similarly to configuring static IPv6 addresses, the setting is
1796 configured as an IPv6 prefix and its prefix length, separated by a
1797 <literal>/
</literal> character. Use multiple
1798 <literal>[IPv6Prefix]
</literal> sections to configure multiple IPv6
1799 prefixes since prefix lifetimes, address autoconfiguration and onlink
1800 status may differ from one prefix to another.
</para></listitem>
1804 <term><varname>PreferredLifetimeSec=
</varname></term>
1805 <term><varname>ValidLifetimeSec=
</varname></term>
1807 <listitem><para>Preferred and valid lifetimes for the prefix measured in
1808 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
1809 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
1810 to
2592000 seconds (
30 days).
</para></listitem>
1817 <title>[Bridge] Section Options
</title>
1818 <para>The
<literal>[Bridge]
</literal> section accepts the
1819 following keys.
</para>
1820 <variablelist class='network-directives'
>
1822 <term><varname>UnicastFlood=
</varname></term>
1824 <para>Takes a boolean. Controls whether the bridge should flood
1825 traffic for which an FDB entry is missing and the destination
1826 is unknown through this port. When unset, the kernel's default will be used.
1831 <term><varname>MulticastFlood=
</varname></term>
1833 <para>Takes a boolean. Controls whether the bridge should flood
1834 traffic for which an MDB entry is missing and the destination
1835 is unknown through this port. When unset, the kernel's default will be used.
1840 <term><varname>MulticastToUnicast=
</varname></term>
1842 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
1843 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
1844 When unset, the kernel's default will be used.
1849 <term><varname>NeighborSuppression=
</varname></term>
1851 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
1852 this port. When unset, the kernel's default will be used.
1857 <term><varname>Learning=
</varname></term>
1859 <para>Takes a boolean. Configures whether MAC address learning is enabled for
1860 this port. When unset, the kernel's default will be used.
1865 <term><varname>HairPin=
</varname></term>
1867 <para>Takes a boolean. Configures whether traffic may be sent back
1868 out of the port on which it was received. When this flag is false, and the bridge
1869 will not forward traffic back out of the receiving port.
1870 When unset, the kernel's default will be used.
</para>
1874 <term><varname>UseBPDU=
</varname></term>
1876 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
1877 processed by the bridge port. When unset, the kernel's default will be used.
</para>
1881 <term><varname>FastLeave=
</varname></term>
1883 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
1884 traffic on a port that receives an IGMP Leave message. It is only used with
1885 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
1889 <term><varname>AllowPortToBeRoot=
</varname></term>
1891 <para>Takes a boolean. Configures whether a given port is allowed to
1892 become a root port. Only used when STP is enabled on the bridge.
1893 When unset, the kernel's default will be used.
</para>
1897 <term><varname>ProxyARP=
</varname></term>
1899 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
1900 When unset, the kernel's default will be used.
</para>
1904 <term><varname>ProxyARPWiFi=
</varname></term>
1906 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
1907 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
1908 When unset, the kernel's default will be used.
</para>
1912 <term><varname>MulticastRouter=
</varname></term>
1914 <para>Configures this port for having multicast routers attached. A port with a multicast
1915 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
1916 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
1917 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
1918 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
1919 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
1923 <term><varname>Cost=
</varname></term>
1925 <para>Sets the
"cost" of sending packets of this interface.
1926 Each port in a bridge may have a different speed and the cost
1927 is used to decide which link to use. Faster interfaces
1928 should have lower costs. It is an integer value between
1 and
1933 <term><varname>Priority=
</varname></term>
1935 <para>Sets the
"priority" of sending packets on this interface.
1936 Each port in a bridge may have a different priority which is used
1937 to decide which link to use. Lower value means higher priority.
1938 It is an integer value between
0 to
63. Networkd does not set any
1939 default, meaning the kernel default value of
32 is used.
</para>
1945 <title>[BridgeFDB] Section Options
</title>
1946 <para>The
<literal>[BridgeFDB]
</literal> section manages the
1947 forwarding database table of a port and accepts the following
1948 keys. Specify several
<literal>[BridgeFDB]
</literal> sections to
1949 configure several static MAC table entries.
</para>
1951 <variablelist class='network-directives'
>
1953 <term><varname>MACAddress=
</varname></term>
1955 <para>As in the
<literal>[Network]
</literal> section. This
1956 key is mandatory.
</para>
1960 <term><varname>Destination=
</varname></term>
1962 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
1966 <term><varname>VLANId=
</varname></term>
1968 <para>The VLAN ID for the new static MAC table entry. If
1969 omitted, no VLAN ID information is appended to the new static MAC
1974 <term><varname>VNI=
</varname></term>
1976 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
1977 the remote VXLAN tunnel endpoint. Takes a number in the range
1-
16777215.
1978 Defaults to unset.
</para>
1985 <title>[CAN] Section Options
</title>
1986 <para>The
<literal>[CAN]
</literal> section manages the Controller Area Network (CAN bus) and accepts the
1987 following keys.
</para>
1988 <variablelist class='network-directives'
>
1990 <term><varname>BitRate=
</varname></term>
1992 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
1993 be used here.
</para>
1997 <term><varname>SamplePoint=
</varname></term>
1999 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2000 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2004 <term><varname>RestartSec=
</varname></term>
2006 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2007 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2008 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2009 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2010 automatic restart off. By default automatic restart is disabled.
</para>
2014 <term><varname>TripleSampling=
</varname></term>
2016 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2017 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
2024 <title>[BridgeVLAN] Section Options
</title>
2025 <para>The
<literal>[BridgeVLAN]
</literal> section manages the VLAN ID configuration of a bridge port and accepts
2026 the following keys. Specify several
<literal>[BridgeVLAN]
</literal> sections to configure several VLAN entries.
2027 The
<varname>VLANFiltering=
</varname> option has to be enabled, see
<literal>[Bridge]
</literal> section in
2028 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2030 <variablelist class='network-directives'
>
2032 <term><varname>VLAN=
</varname></term>
2034 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
2035 from
1 to
4094.
</para>
2039 <term><varname>EgressUntagged=
</varname></term>
2041 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
2042 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
2043 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
2047 <term><varname>PVID=
</varname></term>
2049 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
2050 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
2051 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
2058 <title>Examples
</title>
2060 <title>Static network configuration
</title>
2062 <programlisting># /etc/systemd/network/
50-static.network
2067 Address=
192.168.0.15/
24
2068 Gateway=
192.168.0.1</programlisting>
2070 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
2071 specified gateway will be used for a default route.
</para>
2075 <title>DHCP on ethernet links
</title>
2077 <programlisting># /etc/systemd/network/
80-dhcp.network
2082 DHCP=yes
</programlisting>
2084 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
2085 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
2089 <title>A bridge with two enslaved links
</title>
2091 <programlisting># /etc/systemd/network/
25-bridge-static.network
2096 Address=
192.168.0.15/
24
2098 DNS=
192.168.0.1</programlisting>
2100 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
2105 Bridge=bridge0
</programlisting>
2107 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
2112 Bridge=bridge0
</programlisting>
2114 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
2115 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
2116 and network assigned, and a default route via the specified gateway will be
2117 added. The specified DNS server will be added to the global list of DNS resolvers.
2125 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
2141 EgressUntagged=
300-
400</programlisting>
2143 <para>This overrides the configuration specified in the previous example for the
2144 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
2145 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
2146 untagged when they leave on this interface. Untagged packets which arrive on this
2147 interface will be assigned VLAN ID
42.
</para>
2151 <title>Various tunnels
</title>
2153 <programlisting>/etc/systemd/network/
25-tunnels.network
2164 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
2170 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
2176 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
2182 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
2188 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
2189 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
2193 <title>A bond device
</title>
2195 <programlisting># /etc/systemd/network/
30-bond1.network
2203 <programlisting># /etc/systemd/network/
30-bond1.netdev
2209 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
2211 MACAddress=
52:
54:
00:e9:
64:
41
2217 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
2219 MACAddress=
52:
54:
00:e9:
64:
42
2225 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
2226 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
2227 will be used to acquire an address.
</para>
2231 <title>Virtual Routing and Forwarding (VRF)
</title>
2232 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
2233 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
2234 within the routing table defined during VRF creation. For kernels before
4.8 traffic
2235 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
2237 <programlisting># /etc/systemd/network/
25-vrf.network
2247 <title>MacVTap
</title>
2248 <para>This brings up a network interface
<literal>macvtap-test
</literal>
2249 and attaches it to
<literal>enp0s25
</literal>.
</para>
2250 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
2255 MACVTAP=macvtap-test
2261 <title>See Also
</title>
2263 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
2264 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
2265 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2266 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2267 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
projects / thirdparty / systemd.git / blob