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>RequiredForOnline=
</varname></term>
211 <para>Takes a boolean or a minimum operational state and an optional maximum operational state.
212 Please see
<citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
213 for possible operational states. When
<literal>yes
</literal>, the network is deemed required when
214 determining whether the system is online when running
215 <command>systemd-networkd-wait-online
</command>. When
<literal>no
</literal>, the network is ignored
216 when checking for online state. When a minimum operational state and an optional maximum operational
217 state are set,
<literal>yes
</literal> is implied, and this controls the minimum and maximum
218 operational state required for the network interface to be considered online.
219 Defaults to
<literal>yes
</literal>.
</para>
221 <para>The network will be brought up normally in all cases, but in
222 the event that there is no address being assigned by DHCP or the
223 cable is not plugged in, the link will simply remain offline and be
224 skipped automatically by
<command>systemd-networkd-wait-online
</command>
225 if
<literal>RequiredForOnline=no
</literal>.
</para>
232 <title>[Network] Section Options
</title>
234 <para>The
<literal>[Network]
</literal> section accepts the following keys:
</para>
236 <variablelist class='network-directives'
>
238 <term><varname>Description=
</varname></term>
240 <para>A description of the device. This is only used for
241 presentation purposes.
</para>
245 <term><varname>DHCP=
</varname></term>
247 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
248 <literal>yes
</literal>,
<literal>no
</literal>,
249 <literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults
250 to
<literal>no
</literal>.
</para>
252 <para>Note that DHCPv6 will by default be triggered by Router
253 Advertisement, if that is enabled, regardless of this parameter.
254 By enabling DHCPv6 support explicitly, the DHCPv6 client will
255 be started regardless of the presence of routers on the link,
256 or what flags the routers pass. See
257 <literal>IPv6AcceptRA=
</literal>.
</para>
259 <para>Furthermore, note that by default the domain name
260 specified through DHCP is not used for name resolution.
261 See option
<option>UseDomains=
</option> below.
</para>
263 <para>See the
<literal>[DHCPv4]
</literal> or
<literal>[DHCPv6]
</literal> section below for
264 further configuration options for the DHCP client support.
</para>
268 <term><varname>DHCPServer=
</varname></term>
270 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started. Defaults
271 to
<literal>no
</literal>. Further settings for the DHCP
272 server may be set in the
<literal>[DHCPServer]
</literal>
273 section described below.
</para>
277 <term><varname>LinkLocalAddressing=
</varname></term>
279 <para>Enables link-local address autoconfiguration. Accepts
<literal>yes
</literal>,
280 <literal>no
</literal>,
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
281 <literal>fallback
</literal>, or
<literal>ipv4-fallback
</literal>. If
282 <literal>fallback
</literal> or
<literal>ipv4-fallback
</literal> is specified, then an IPv4
283 link-local address is configured only when DHCPv4 fails. If
<literal>fallback
</literal>,
284 an IPv6 link-local address is always configured, and if
<literal>ipv4-fallback
</literal>,
285 the address is not configured. Note that, the fallback mechanism works only when DHCPv4
286 client is enabled, that is, it requires
<literal>DHCP=yes
</literal> or
287 <literal>DHCP=ipv4
</literal>. If
<varname>Bridge=
</varname> is set, defaults to
288 <literal>no
</literal>, and if not, defaults to
<literal>ipv6
</literal>.
293 <term><varname>IPv4LLRoute=
</varname></term>
295 <para>Takes a boolean. If set to true, sets up the route needed for
296 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
302 <term><varname>DefaultRouteOnDevice=
</varname></term>
304 <para>Takes a boolean. If set to true, sets up the default route bound to the interface.
305 Defaults to false. This is useful when creating routes on point-to-point interfaces.
306 This is equivalent to e.g. the following.
307 <programlisting>ip route add default dev veth99
</programlisting></para>
311 <term><varname>IPv6Token=
</varname></term>
313 <para>Specifies an optional address generation mode and a required IPv6 address. If
314 the mode is present, the two parts must be separated with a colon
315 <literal><replaceable>mode
</replaceable>:
<replaceable>address
</replaceable></literal>. The
316 address generation mode may be either
<constant>prefixstable
</constant> or
317 <constant>static
</constant>. If not specified,
<constant>static
</constant> is assumed.
319 <para>When the mode is set to
<constant>static
</constant>, or unspecified, the lower bits of
320 the supplied address are combined with the upper bits of a prefix received in a Router Advertisement
321 message to form a complete address. Note that if multiple prefixes are received in an RA message, or in
322 multiple RA messages, addresses will be formed from each of them using the supplied address. This
323 mode implements SLAAC but uses a static interface identifier instead of an identifier generated
324 using the EUI-
64 algorithm. Because the interface identifier is static, if Duplicate Address Detection
325 detects that the computed address is a duplicate (in use by another node on the link), then this
326 mode will fail to provide an address for that prefix.
328 <para>When the mode is set to
<literal>prefixstable
</literal> the RFC
7217 algorithm for generating
329 interface identifiers will be used, but only when a prefix received in an RA message matches the supplied address.
330 See
<ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink>. Prefix matching will be attempted
331 against each
<constant>prefixstable
</constant> IPv6Token variable provided in the configuration; if a received
332 prefix does not match any of the provided addresses, then the EUI-
64 algorithm will be used to form
333 an interface identifier for that prefix. This mode is also SLAAC, but with a potentially stable interface
334 identifier which does not directly map to the interface's hardware address.
336 Note that the
<constant>prefixstable
</constant> algorithm includes both the interface's name and
337 MAC address in the hash used to compute the interface identifier, so if either of those are changed the resulting
338 interface identifier (and address) will change, even if the prefix received in the RA message has not changed.
340 Note that if multiple
<constant>prefixstable
</constant> IPv6Token variables are supplied with addresses that
341 match a prefix received in an RA message, only the first one will be used to generate addresses.
346 <term><varname>LLMNR=
</varname></term>
348 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
350 url=
"https://tools.ietf.org/html/rfc4795">Link-Local
351 Multicast Name Resolution
</ulink> on the link. When set to
352 <literal>resolve
</literal>, only resolution is enabled,
353 but not host registration and announcement. Defaults to
354 true. This setting is read by
355 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
359 <term><varname>MulticastDNS=
</varname></term>
361 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
363 url=
"https://tools.ietf.org/html/rfc6762">Multicast
364 DNS
</ulink> support on the link. When set to
365 <literal>resolve
</literal>, only resolution is enabled,
366 but not host or service registration and
367 announcement. Defaults to false. This setting is read by
368 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
372 <term><varname>DNSOverTLS=
</varname></term>
374 <para>Takes a boolean or
<literal>opportunistic
</literal>.
377 url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink>
379 When set to
<literal>opportunistic
</literal>, compatibility with
380 non-DNS-over-TLS servers is increased, by automatically
381 turning off DNS-over-TLS servers in this case.
382 This option defines a per-interface setting for
383 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
384 global
<varname>DNSOverTLS=
</varname> option. Defaults to
385 false. This setting is read by
386 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
390 <term><varname>DNSSEC=
</varname></term>
392 <para>Takes a boolean. or
393 <literal>allow-downgrade
</literal>. When true, enables
395 url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink>
396 DNS validation support on the link. When set to
397 <literal>allow-downgrade
</literal>, compatibility with
398 non-DNSSEC capable networks is increased, by automatically
399 turning off DNSSEC in this case. This option defines a
400 per-interface setting for
401 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
402 global
<varname>DNSSEC=
</varname> option. Defaults to
403 false. This setting is read by
404 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
408 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
409 <listitem><para>A space-separated list of DNSSEC negative
410 trust anchor domains. If specified and DNSSEC is enabled,
411 look-ups done via the interface's DNS server will be subject
412 to the list of negative trust anchors, and not require
413 authentication for the specified domains, or anything below
414 it. Use this to disable DNSSEC authentication for specific
415 private domains, that cannot be proven valid using the
416 Internet DNS hierarchy. Defaults to the empty list. This
418 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
422 <term><varname>LLDP=
</varname></term>
424 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
425 implemented on professional routers and bridges which announces which physical port a system is connected
426 to, as well as other related data. Accepts a boolean or the special value
427 <literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
428 neighbors maintained. If
<literal>routers-only
</literal> is set only LLDP data of various types of routers
429 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
430 others). If false, LLDP reception is disabled. Defaults to
<literal>routers-only
</literal>. Use
431 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
432 collected neighbor data. LLDP is only available on Ethernet links. See
<varname>EmitLLDP=
</varname> below
433 for enabling LLDP packet emission from the local system.
438 <term><varname>EmitLLDP=
</varname></term>
440 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
441 <literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
442 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
443 a short LLDP packet with information about the local system is sent out in regular intervals on the
444 link. The LLDP packet will contain information about the local hostname, the local machine ID (as stored
445 in
<citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
446 local interface name, as well as the pretty hostname of the system (as set in
447 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
448 emission is only available on Ethernet links. Note that this setting passes data suitable for
449 identification of host to the network and should thus not be enabled on untrusted networks, where such
450 identification data should not be made available. Use this option to permit other systems to identify on
451 which interfaces they are connected to this system. The three special values control propagation of the
452 LLDP packets. The
<literal>nearest-bridge
</literal> setting permits propagation only to the nearest
453 connected bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays, but
454 not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until a customer bridge
455 is reached. For details about these concepts, see
<ulink
456 url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>. Note that
457 configuring this setting to true is equivalent to
<literal>nearest-bridge
</literal>, the recommended and
458 most restricted level of propagation. See
<varname>LLDP=
</varname> above for an option to enable LLDP
464 <term><varname>BindCarrier=
</varname></term>
466 <para>A link name or a list of link names. When set, controls the behavior of the current
467 link. When all links in the list are in an operational down state, the current link is brought
468 down. When at least one link has carrier, the current interface is brought up.
473 <term><varname>Address=
</varname></term>
475 <para>A static IPv4 or IPv6 address and its prefix length,
476 separated by a
<literal>/
</literal> character. Specify
477 this key more than once to configure several addresses.
478 The format of the address must be as described in
479 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
480 This is a short-hand for an [Address] section only
481 containing an Address key (see below). This option may be
482 specified more than once.
485 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
486 (for IPv6), a new address range of the requested size is automatically allocated from a
487 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
488 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
489 all known network configuration files to avoid address range conflicts. The default system-wide
490 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.
491 This functionality is useful to manage a large number of dynamically created network interfaces
492 with the same network configuration and automatic address range assignment.
</para>
497 <term><varname>Gateway=
</varname></term>
499 <para>The gateway address, which must be in the format
501 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
502 This is a short-hand for a [Route] section only containing
503 a Gateway key. This option may be specified more than
508 <term><varname>DNS=
</varname></term>
510 <para>A DNS server address, which must be in the format
512 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
513 This option may be specified more than once. This setting is read by
514 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
518 <term><varname>Domains=
</varname></term>
520 <para>A whitespace-separated list of domains which should be resolved using the DNS servers on
521 this link. Each item in the list should be a domain name, optionally prefixed with a tilde
522 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
523 domains without the prefix are called
"search domains" and are first used as search suffixes for
524 extending single-label hostnames (hostnames containing no dots) to become fully qualified
525 domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
526 specified search domains are appended to it in turn, converting it into a fully qualified domain
527 name, until one of them may be successfully resolved.
</para>
529 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for hostnames
530 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
531 the DNS servers configured for this interface. The domain routing logic is particularly useful on
532 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
534 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
535 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
536 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
537 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
538 if a link on which they are connected is available.
</para>
540 <para>This setting is read by
541 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
542 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
543 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
544 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
545 name servers limited to a specific link.
</para>
549 <term><varname>DNSDefaultRoute=
</varname></term>
551 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
552 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
553 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
554 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
555 queries not matching any link's configured domains will be routed to this link if it has no routing-only
556 domains configured.
</para>
560 <term><varname>NTP=
</varname></term>
562 <para>An NTP server address. This option may be specified more than once. This setting is read by
563 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
567 <term><varname>IPForward=
</varname></term>
568 <listitem><para>Configures IP packet forwarding for the
569 system. If enabled, incoming packets on any network
570 interface will be forwarded to any other interfaces
571 according to the routing table. Takes a boolean,
572 or the values
<literal>ipv4
</literal> or
573 <literal>ipv6
</literal>, which only enable IP packet
574 forwarding for the specified address family. This controls
575 the
<filename>net.ipv4.ip_forward
</filename> and
576 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
577 options of the network interface (see
<ulink
578 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
579 for details about sysctl options). Defaults to
580 <literal>no
</literal>.
</para>
582 <para>Note: this setting controls a global kernel option,
583 and does so one way only: if a network that has this setting
584 enabled is set up the global setting is turned on. However,
585 it is never turned off again, even after all networks with
586 this setting enabled are shut down again.
</para>
588 <para>To allow IP packet forwarding only between specific
589 network interfaces use a firewall.
</para>
593 <term><varname>IPMasquerade=
</varname></term>
594 <listitem><para>Configures IP masquerading for the network
595 interface. If enabled, packets forwarded from the network
596 interface will be appear as coming from the local host.
597 Takes a boolean argument. Implies
598 <varname>IPForward=ipv4
</varname>. Defaults to
599 <literal>no
</literal>.
</para></listitem>
602 <term><varname>IPv6PrivacyExtensions=
</varname></term>
603 <listitem><para>Configures use of stateless temporary
604 addresses that change over time (see
<ulink
605 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
606 Privacy Extensions for Stateless Address Autoconfiguration
607 in IPv6). Takes a boolean or the special values
608 <literal>prefer-public
</literal> and
609 <literal>kernel
</literal>. When true, enables the privacy
610 extensions and prefers temporary addresses over public
611 addresses. When
<literal>prefer-public
</literal>, enables the
612 privacy extensions, but prefers public addresses over
613 temporary addresses. When false, the privacy extensions
614 remain disabled. When
<literal>kernel
</literal>, the kernel's
615 default setting will be left in place. Defaults to
616 <literal>no
</literal>.
</para></listitem>
619 <term><varname>IPv6AcceptRA=
</varname></term>
620 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
621 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they may
622 trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or if no
623 routers are found on the link. The default is to disable RA reception for bridge devices or when IP
624 forwarding is enabled, and to enable it otherwise. Cannot be enabled on bond devices and when link
625 local adressing is disabled.
</para>
627 <para>Further settings for the IPv6 RA support may be configured in the
628 <literal>[IPv6AcceptRA]
</literal> section, see below.
</para>
630 <para>Also see
<ulink
631 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink> in the kernel
632 documentation regarding
<literal>accept_ra
</literal>, but note that systemd's setting of
633 <constant>1</constant> (i.e. true) corresponds to kernel's setting of
<constant>2</constant>.
</para>
635 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
636 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
637 RA protocol is used, and the kernel's own implementation remains disabled, since
638 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
639 and these are not available from the kernel if the kernel's own implementation is used.
</para>
643 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
644 <listitem><para>Configures the amount of IPv6 Duplicate
645 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
649 <term><varname>IPv6HopLimit=
</varname></term>
650 <listitem><para>Configures IPv6 Hop Limit. For each router that
651 forwards the packet, the hop limit is decremented by
1. When the
652 hop limit field reaches zero, the packet is discarded.
653 When unset, the kernel's default will be used.
657 <term><varname>IPv4ProxyARP=
</varname></term>
658 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
659 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
660 the router accepts responsibility for routing packets to the
"real" destination. (see
<ulink
661 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
662 When unset, the kernel's default will be used.
666 <term><varname>IPv6ProxyNDP=
</varname></term>
667 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
668 Protocol) is a technique for IPv6 to allow routing of addresses to a different
669 destination when peers expect them to be present on a certain physical link.
670 In this case a router answers Neighbour Advertisement messages intended for
671 another machine by offering its own MAC address as destination.
672 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
673 Advertisement messages for addresses in the IPv6 neighbor proxy table,
674 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
675 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
676 interface depending on this option.
677 When unset, the kernel's default will be used.
681 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
682 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
683 proxied. This option may be specified more than once. systemd-networkd will add the
684 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
685 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
686 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
690 <term><varname>IPv6PrefixDelegation=
</varname></term>
691 <listitem><para>Whether to enable or disable Router Advertisement sending on a link.
692 Allowed values are
<literal>static
</literal> which distributes prefixes as defined in
693 the
<literal>[IPv6PrefixDelegation]
</literal> and any
<literal>[IPv6Prefix]
</literal>
694 sections,
<literal>dhcpv6
</literal> which requests prefixes using a DHCPv6 client
695 configured for another link and any values configured in the
696 <literal>[IPv6PrefixDelegation]
</literal> section while ignoring all static prefix
697 configuration sections,
<literal>yes
</literal> which uses both static configuration
698 and DHCPv6, and
<literal>false
</literal> which turns off IPv6 prefix delegation
699 altogether. Defaults to
<literal>false
</literal>. See the
700 <literal>[IPv6PrefixDelegation]
</literal> and the
<literal>[IPv6Prefix]
</literal>
701 sections for more configuration options.
705 <term><varname>IPv6MTUBytes=
</varname></term>
706 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
707 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
711 <term><varname>Bridge=
</varname></term>
713 <para>The name of the bridge to add the link to. See
714 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
719 <term><varname>Bond=
</varname></term>
721 <para>The name of the bond to add the link to. See
722 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
727 <term><varname>VRF=
</varname></term>
729 <para>The name of the VRF to add the link to. See
730 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
735 <term><varname>VLAN=
</varname></term>
737 <para>The name of a VLAN to create on the link. See
738 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
739 This option may be specified more than once.
</para>
743 <term><varname>IPVLAN=
</varname></term>
745 <para>The name of a IPVLAN 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>MACVLAN=
</varname></term>
753 <para>The name of a MACVLAN 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>VXLAN=
</varname></term>
761 <para>The name of a VXLAN 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>Tunnel=
</varname></term>
769 <para>The name of a Tunnel 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>MACsec=
</varname></term>
777 <para>The name of a MACsec device 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>ActiveSlave=
</varname></term>
785 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
786 option is only valid for following modes:
787 <literal>active-backup
</literal>,
788 <literal>balance-alb
</literal> and
789 <literal>balance-tlb
</literal>. Defaults to false.
794 <term><varname>PrimarySlave=
</varname></term>
796 <para>Takes a boolean. Specifies which slave is the primary device. The specified
797 device will always be the active slave while it is available. Only when the
798 primary is off-line will alternate devices be used. This is useful when
799 one slave is preferred over another, e.g. when one slave has higher throughput
800 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
802 <literal>active-backup
</literal>,
803 <literal>balance-alb
</literal> and
804 <literal>balance-tlb
</literal>. Defaults to false.
809 <term><varname>ConfigureWithoutCarrier=
</varname></term>
811 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
817 <term><varname>IgnoreCarrierLoss=
</varname></term>
819 <para>A boolean. Allows networkd to retain both the static and dynamic configuration of the
820 interface even if its carrier is lost. Defaults to false.
825 <term><varname>Xfrm=
</varname></term>
827 <para>The name of the xfrm to create on the link. See
828 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
829 This option may be specified more than once.
</para>
833 <term><varname>KeepConfiguration=
</varname></term>
835 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
836 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
837 will not drop static addresses and routes on starting up process. When set to
838 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
839 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
840 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
841 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
842 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
843 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
844 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
<literal>no
</literal>.
854 <title>[Address] Section Options
</title>
856 <para>An
<literal>[Address]
</literal> section accepts the
857 following keys. Specify several
<literal>[Address]
</literal>
858 sections to configure several addresses.
</para>
860 <variablelist class='network-directives'
>
862 <term><varname>Address=
</varname></term>
864 <para>As in the
<literal>[Network]
</literal> section. This key is mandatory. Each
865 <literal>[Address]
</literal> section can contain one
<varname>Address=
</varname> setting.
</para>
869 <term><varname>Peer=
</varname></term>
871 <para>The peer address in a point-to-point connection.
872 Accepts the same format as the
<varname>Address=
</varname>
877 <term><varname>Broadcast=
</varname></term>
879 <para>The broadcast address, which must be in the format
881 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
882 This key only applies to IPv4 addresses. If it is not
883 given, it is derived from the
<varname>Address=
</varname>
888 <term><varname>Label=
</varname></term>
890 <para>An address label.
</para>
894 <term><varname>PreferredLifetime=
</varname></term>
896 <para>Allows the default
"preferred lifetime" of the address to be overridden.
897 Only three settings are accepted:
<literal>forever
</literal> or
<literal>infinity
</literal>
898 which is the default and means that the address never expires, and
<literal>0</literal> which means
899 that the address is considered immediately
"expired" and will not be used,
900 unless explicitly requested. A setting of PreferredLifetime=
0 is useful for
901 addresses which are added to be used only by a specific application,
902 which is then configured to use them explicitly.
</para>
906 <term><varname>Scope=
</varname></term>
908 <para>The scope of the address, which can be
<literal>global
</literal>,
909 <literal>link
</literal> or
<literal>host
</literal> or an unsigned integer ranges
0 to
255.
910 Defaults to
<literal>global
</literal>.
</para>
914 <term><varname>HomeAddress=
</varname></term>
916 <para>Takes a boolean. Designates this address the
"home address" as defined in
917 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
918 Supported only on IPv6. Defaults to false.
</para>
922 <term><varname>DuplicateAddressDetection=
</varname></term>
924 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
925 <literal>both
</literal>,
<literal>none
</literal>. When
<literal>ipv4
</literal>,
926 performs IPv4 Duplicate Address Detection. See
927 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
928 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
929 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>.
930 Defaults to
<literal>ipv6
</literal>.
</para>
934 <term><varname>ManageTemporaryAddress=
</varname></term>
936 <para>Takes a boolean. If true the kernel manage temporary addresses created
937 from this one as template on behalf of Privacy Extensions
938 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
939 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
940 The given address needs to have a prefix length of
64. This flag allows using privacy
941 extensions in a manually configured network, just like if stateless auto-configuration
942 was active. Defaults to false.
</para>
946 <term><varname>AddPrefixRoute=
</varname></term>
948 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
949 Defaults to true.
</para>
953 <term><varname>AutoJoin=
</varname></term>
955 <para>Takes a boolean. Joining multicast group on ethernet level via
956 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
957 IGMP snooping since the switch would not replicate multicast packets on ports that did not
958 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
959 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
960 that enables then to do the required join. By extending ip address command with option
961 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
962 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
963 Defaults to
<literal>no
</literal>.
</para>
970 <title>[Neighbor] Section Options
</title>
971 <para>A
<literal>[Neighbor]
</literal> section accepts the
972 following keys. The neighbor section adds a permanent, static
973 entry to the neighbor table (IPv6) or ARP table (IPv4) for
974 the given hardware address on the links matched for the network.
975 Specify several
<literal>[Neighbor]
</literal> sections to configure
976 several static neighbors.
</para>
978 <variablelist class='network-directives'
>
980 <term><varname>Address=
</varname></term>
982 <para>The IP address of the neighbor.
</para>
986 <term><varname>LinkLayerAddress=
</varname></term>
988 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
995 <title>[IPv6AddressLabel] Section Options
</title>
997 <para>An
<literal>[IPv6AddressLabel]
</literal> section accepts the
998 following keys. Specify several
<literal>[IPv6AddressLabel]
</literal>
999 sections to configure several address labels. IPv6 address labels are
1000 used for address selection. See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>.
1001 Precedence is managed by userspace, and only the label itself is stored in the kernel
</para>
1003 <variablelist class='network-directives'
>
1005 <term><varname>Label=
</varname></term>
1007 <para> The label for the prefix (an unsigned integer) ranges
0 to
4294967294.
1008 0xffffffff is reserved. This key is mandatory.
</para>
1012 <term><varname>Prefix=
</varname></term>
1014 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
1015 This key is mandatory.
</para>
1022 <title>[RoutingPolicyRule] Section Options
</title>
1024 <para>An
<literal>[RoutingPolicyRule]
</literal> section accepts the
1025 following keys. Specify several
<literal>[RoutingPolicyRule]
</literal>
1026 sections to configure several rules.
</para>
1028 <variablelist class='network-directives'
>
1030 <term><varname>TypeOfService=
</varname></term>
1032 <para>Specifies the type of service to match a number between
0 to
255.
</para>
1036 <term><varname>From=
</varname></term>
1038 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1042 <term><varname>To=
</varname></term>
1044 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1048 <term><varname>FirewallMark=
</varname></term>
1050 <para>Specifies the iptables firewall mark value to match (a number between
1 and
4294967295).
</para>
1054 <term><varname>Table=
</varname></term>
1056 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes
1057 one of
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
1058 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1062 <term><varname>Priority=
</varname></term>
1064 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1065 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1069 <term><varname>IncomingInterface=
</varname></term>
1071 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1075 <term><varname>OutgoingInterface=
</varname></term>
1077 <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>
1081 <term><varname>SourcePort=
</varname></term>
1083 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1084 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1088 <term><varname>DestinationPort=
</varname></term>
1090 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1091 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1095 <term><varname>IPProtocol=
</varname></term>
1097 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1098 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1099 <literal>17</literal> for
<literal>udp
</literal>.
1100 Defaults to unset.
</para>
1104 <term><varname>InvertRule=
</varname></term>
1106 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1110 <term><varname>Family=
</varname></term>
1112 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1113 <literal>both
</literal>. By default, the address family is determined by the address
1114 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1115 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1116 <literal>ipv4
</literal>.
</para>
1120 <term><varname>User=
</varname></term>
1122 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1127 <term><varname>SuppressPrefixLength=
</varname></term>
1129 <para>Takes a number
<replaceable>N
</replaceable> in the range
0-
128 and rejects routing
1130 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1138 <title>[NextHop] Section Options
</title>
1139 <para>The
<literal>[NextHop]
</literal> section accepts the
1140 following keys. Specify several
<literal>[NextHop]
</literal>
1141 sections to configure several nexthop. Nexthop is used to manipulate entries in the kernel's nexthop
1144 <variablelist class='network-directives'
>
1146 <term><varname>Gateway=
</varname></term>
1148 <para>As in the
<literal>[Network]
</literal> section. This is mandatory.
</para>
1152 <term><varname>Id=
</varname></term>
1154 <para>The id of the nexthop (an unsigned integer). If unspecified or '
0' then automatically chosen by kernel.
</para>
1161 <title>[Route] Section Options
</title>
1162 <para>The
<literal>[Route]
</literal> section accepts the
1163 following keys. Specify several
<literal>[Route]
</literal>
1164 sections to configure several routes.
</para>
1166 <variablelist class='network-directives'
>
1168 <term><varname>Gateway=
</varname></term>
1170 <para>Takes the gateway address or special value
<literal>_dhcp
</literal>. If
1171 <literal>_dhcp
</literal>, then the gateway address provided by DHCP (or in the IPv6 case,
1172 provided by IPv6 RA) is used.
</para>
1176 <term><varname>GatewayOnLink=
</varname></term>
1178 <para>Takes a boolean. If set to true, the kernel does not have
1179 to check if the gateway is reachable directly by the current machine (i.e., the kernel does
1180 not need to check if the gateway is attached to the local network), so that we can insert the
1181 route in the kernel table without it being complained about. Defaults to
<literal>no
</literal>.
1186 <term><varname>Destination=
</varname></term>
1188 <para>The destination prefix of the route. Possibly
1189 followed by a slash and the prefix length. If omitted, a
1190 full-length host route is assumed.
</para>
1194 <term><varname>Source=
</varname></term>
1196 <para>The source prefix of the route. Possibly followed by
1197 a slash and the prefix length. If omitted, a full-length
1198 host route is assumed.
</para>
1202 <term><varname>Metric=
</varname></term>
1204 <para>The metric of the route (an unsigned integer).
</para>
1208 <term><varname>IPv6Preference=
</varname></term>
1210 <para>Specifies the route preference as defined in
<ulink
1211 url=
"https://tools.ietf.org/html/rfc4191">RFC4191
</ulink> for Router Discovery messages.
1212 Which can be one of
<literal>low
</literal> the route has a lowest priority,
1213 <literal>medium
</literal> the route has a default priority or
1214 <literal>high
</literal> the route has a highest priority.
</para>
1218 <term><varname>Scope=
</varname></term>
1220 <para>The scope of the route, which can be
<literal>global
</literal>,
<literal>site
</literal>,
1221 <literal>link
</literal>,
<literal>host
</literal>, or
<literal>nowhere
</literal>. For IPv4 route,
1222 defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
<literal>local
</literal>
1223 or
<literal>nat
</literal>, and
<literal>link
</literal> if
<varname>Type=
</varname> is
1224 <literal>broadcast
</literal>,
<literal>multicast
</literal>, or
<literal>anycast
</literal>.
1225 In other cases, defaults to
<literal>global
</literal>.
</para>
1229 <term><varname>PreferredSource=
</varname></term>
1231 <para>The preferred source address of the route. The address
1232 must be in the format described in
1233 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1237 <term><varname>Table=
</varname></term>
1239 <para>The table identifier for the route. Takes
<literal>default
</literal>,
1240 <literal>main
</literal>,
<literal>local
</literal> or a number between
1 and
4294967295.
1241 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1242 If unset and
<varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1243 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1244 In other cases, defaults to
<literal>main
</literal>.
1249 <term><varname>Protocol=
</varname></term>
1251 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1252 <literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1253 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1258 <term><varname>Type=
</varname></term>
1260 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1261 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1262 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1263 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1264 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1265 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1266 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1267 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1268 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1269 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1270 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1275 <term><varname>InitialCongestionWindow=
</varname></term>
1277 <para>The TCP initial congestion window is used during the start of a TCP connection. During the start of a TCP
1278 session, when a client requests a resource, the server's initial congestion window determines how many data bytes
1279 will be sent during the initial burst of data. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual
1280 suffixes K, M, G are supported and are understood to the base of
1024. When unset, the kernel's default will be used.
1285 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1287 <para>The TCP initial advertised receive window is the amount of receive data (in bytes) that can initially be buffered at one time
1288 on a connection. The sending host can send only that amount of data before waiting for an acknowledgment and window update
1289 from the receiving host. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual suffixes K, M, G are supported
1290 and are understood to the base of
1024. When unset, the kernel's default will be used.
1295 <term><varname>QuickAck=
</varname></term>
1297 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1302 <term><varname>FastOpenNoCookie=
</varname></term>
1304 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1305 When unset, the kernel's default will be used.
1310 <term><varname>TTLPropagate=
</varname></term>
1312 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1313 When unset, the kernel's default will be used.
1318 <term><varname>MTUBytes=
</varname></term>
1320 <para>The maximum transmission unit in bytes to set for the
1321 route. The usual suffixes K, M, G, are supported and are
1322 understood to the base of
1024.
</para>
1323 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1324 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1328 <term><varname>IPServiceType=
</varname></term>
1330 <para>Takes string;
<literal>CS6
</literal> or
<literal>CS4
</literal>. Used to set IP
1331 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.
</para>
1335 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1337 <para>Configures multipath route. Multipath routing is the technique of using multiple
1338 alternative paths through a network. Takes gateway address. Optionally, takes a network
1339 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for
1340 this multipath route separated with whitespace. This setting can be specified multiple
1341 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
1348 <title>[DHCPv4] Section Options
</title>
1349 <para>The
<literal>[DHCPv4]
</literal> section configures the
1350 DHCPv4 client, if it is enabled with the
1351 <varname>DHCP=
</varname> setting described above:
</para>
1353 <variablelist class='network-directives'
>
1355 <term><varname>UseDNS=
</varname></term>
1357 <para>When true (the default), the DNS servers received
1358 from the DHCP server will be used and take precedence over
1359 any statically configured ones.
</para>
1361 <para>This corresponds to the
<option>nameserver
</option>
1362 option in
<citerefentry
1363 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1367 <term><varname>RoutesToDNS=
</varname></term>
1369 <para>When true, the routes to the DNS servers received from the DHCP server will be
1370 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored.
1371 Defaults to false.
</para>
1375 <term><varname>UseNTP=
</varname></term>
1377 <para>When true (the default), the NTP servers received
1378 from the DHCP server will be used by systemd-timesyncd
1379 and take precedence over any statically configured ones.
</para>
1383 <term><varname>UseSIP=
</varname></term>
1385 <para>When true (the default), the SIP servers received
1386 from the DHCP server will be saved at the state files and can be
1387 read via
<function>sd_network_link_get_sip_servers()
</function> function.
</para>
1392 <term><varname>UseMTU=
</varname></term>
1394 <para>When true, the interface maximum transmission unit
1395 from the DHCP server will be used on the current link.
1396 If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
1397 Defaults to false.
</para>
1401 <term><varname>Anonymize=
</varname></term>
1403 <para>Takes a boolean. When true, the options sent to the DHCP server will
1404 follow the
<ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink>
1405 (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying information.
1406 Defaults to false.
</para>
1408 <para>This option should only be set to true when
1409 <varname>MACAddressPolicy=
</varname> is set to
<literal>random
</literal>
1411 project='man-pages'
><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
1413 <para>Note that this configuration will overwrite others.
1414 In concrete, the following variables will be ignored:
1415 <varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1416 <varname>UseRoutes=
</varname>,
<varname>UseMTU=
</varname>,
1417 <varname>VendorClassIdentifier=
</varname>,
<varname>UseTimezone=
</varname>.
</para>
1419 <para>With this option enabled DHCP requests will mimic those generated by Microsoft Windows, in
1420 order to reduce the ability to fingerprint and recognize installations. This means DHCP request
1421 sizes will grow and lease data will be more comprehensive than normally, though most of the
1422 requested data is not actually used.
</para>
1426 <term><varname>SendHostname=
</varname></term>
1428 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1429 Note that the machine's hostname must consist only of
7-bit ASCII lower-case characters and
1430 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1431 sent even if this is set to true.
</para>
1436 <term><varname>MUDURL=
</varname></term>
1438 <para>When configured, the Manufacturer Usage Descriptions (MUD) URL will be sent to the
1439 DHCPv4 server. Takes an URL of length up to
255 characters. A superficial verification that
1440 the string is a valid URL will be performed. DHCPv4 clients are intended to have at most one
1441 MUD URL associated with them. See
1442 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
1447 <term><varname>UseHostname=
</varname></term>
1449 <para>When true (the default), the hostname received from
1450 the DHCP server will be set as the transient hostname of the system.
1455 <term><varname>Hostname=
</varname></term>
1457 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1458 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1459 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1463 <term><varname>UseDomains=
</varname></term>
1465 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1466 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1467 the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name received from
1468 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1469 the
<option>Domains=
</option> setting when the argument is prefixed with
<literal>~
</literal>. Defaults to
1472 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1473 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
1474 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1475 single-label names.
</para>
1477 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1478 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1482 <term><varname>UseRoutes=
</varname></term>
1484 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1485 routing table with a metric of
1024, and a scope of
"global",
"link" or
"host", depending on the route's
1486 destination and gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the
1487 link's own address, the scope will be set to
"host". Otherwise if the gateway is null (a direct route), a
1488 "link" scope will be used. For anything else, scope defaults to
"global".
</para>
1492 <term><varname>UseGateway=
</varname></term>
1494 <para>When true (the default), the gateway will be requested from the DHCP server and added to the
1495 routing table with a metric of
1024, and a scope of
"link".
</para>
1499 <term><varname>UseTimezone=
</varname></term>
1501 <listitem><para>When true, the timezone received from the
1502 DHCP server will be set as timezone of the local
1503 system. Defaults to
<literal>no
</literal>.
</para></listitem>
1507 <term><varname>ClientIdentifier=
</varname></term>
1509 <para>The DHCPv4 client identifier to use. Takes one of
<literal>mac
</literal>,
<literal>duid
</literal> or
<literal>duid-only
</literal>.
1510 If set to
<literal>mac
</literal>, the MAC address of the link is used.
1511 If set to
<literal>duid
</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1512 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.
1513 Defaults to
<literal>duid
</literal>.
</para>
1518 <term><varname>VendorClassIdentifier=
</varname></term>
1520 <para>The vendor class identifier used to identify vendor
1521 type and configuration.
</para>
1526 <term><varname>UserClass=
</varname></term>
1528 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1529 it represents. The information contained in this option is a string that represents the user class of which
1530 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1531 service to classify clients. Takes a whitespace-separated list of strings.
</para>
1536 <term><varname>MaxAttempts=
</varname></term>
1538 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1539 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>.
1540 Note that the time between retries is increased exponentially, so the network will not be
1541 overloaded even if this number is high.
</para>
1546 <term><varname>DUIDType=
</varname></term>
1548 <para>Override the global
<varname>DUIDType
</varname> setting for this network. See
1549 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1550 for a description of possible values.
</para>
1555 <term><varname>DUIDRawData=
</varname></term>
1557 <para>Override the global
<varname>DUIDRawData
</varname> setting for this network. See
1558 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1559 for a description of possible values.
</para>
1564 <term><varname>IAID=
</varname></term>
1566 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned integer.
</para>
1571 <term><varname>RequestBroadcast=
</varname></term>
1573 <para>Request the server to use broadcast messages before
1574 the IP address has been configured. This is necessary for
1575 devices that cannot receive RAW packets, or that cannot
1576 receive packets at all before an IP address has been
1577 configured. On the other hand, this must not be enabled on
1578 networks where broadcasts are filtered out.
</para>
1583 <term><varname>RouteMetric=
</varname></term>
1585 <para>Set the routing metric for routes specified by the
1591 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1593 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1594 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1596 <para>When used in combination with
<varname>VRF=
</varname> the
1597 VRF's routing table is used unless this parameter is specified.
1603 <term><varname>RouteMTUBytes=
</varname></term>
1605 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.
</para>
1610 <term><varname>ListenPort=
</varname></term>
1612 <para>Allow setting custom port for the DHCP client to listen on.
</para>
1617 <term><varname>SendRelease=
</varname></term>
1619 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops.
1620 Defaults to true.
</para>
1625 <term><varname>SendDecline=
</varname></term>
1627 <para>A boolen. When
<literal>true
</literal>, DHCPv4 clients receives IP address from DHCP server.
1628 After new IP is received, DHCPv4 performs IPv4 Duplicate Address Detection. If duplicate use of IP is detected
1629 the DHCPv4 client rejects the IP by sending a DHCPDECLINE packet DHCP clients try to obtain an IP address again.
1630 See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
1631 Defaults to
<literal>unset
</literal>.
</para>
1636 <term><varname>BlackList=
</varname></term>
1638 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are rejected.
</para>
1643 <term><varname>RequestOptions=
</varname></term>
1645 <para>A whitespace-separated list of integers in the range
1–
254.
</para>
1650 <term><varname>SendOption=
</varname></term>
1652 <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data type
1653 and data separated with a colon
1654 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1655 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1656 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1657 <literal>string
</literal>. Special characters in the data string may be escaped using
1658 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1659 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1660 then all options specified earlier are cleared. Defaults to unset.
</para>
1665 <term><varname>SendVendorOption=
</varname></term>
1667 <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data type
1668 and data separated with a colon
1669 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1670 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1671 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1672 <literal>string
</literal>. Special characters in the data string may be escaped using
1673 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1674 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1675 then all options specified earlier are cleared. Defaults to unset.
</para>
1682 <title>[DHCPv6] Section Options
</title>
1683 <para>The
<literal>[DHCPv6]
</literal> section configures the DHCPv6 client, if it is enabled with the
1684 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
</para>
1686 <variablelist class='network-directives'
>
1688 <term><varname>UseDNS=
</varname></term>
1689 <term><varname>UseNTP=
</varname></term>
1691 <para>As in the
<literal>[DHCPv4]
</literal> section.
</para>
1696 <term><varname>RapidCommit=
</varname></term>
1698 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1699 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1700 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1701 four-method exchange (solicit, advertise, request, and reply). The two-message exchange provides
1702 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1703 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
1704 Defaults to true.
</para>
1709 <term><varname>MUDURL=
</varname></term>
1711 <para>When configured, the Manufacturer Usage Descriptions (MUD) URL will be sent to the DHCPV6 server.
1712 Takes an URL of length up to
255 characters. A superficial verification that the string is a valid URL
1713 will be performed. DHCPv6 clients are intended to have at most one MUD URL associated with them. See
1714 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink>.
</para>
1719 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
1721 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
1722 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
1723 makes DHCPv6 request network information in a stateless manner using a two-message Information
1724 Request and Information Reply message exchange.
1725 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
1726 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
1727 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
1728 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
1729 By default this option is set to 'false', enable it if no prefixes are delegated when the device
1730 should be acting as a CE router.
</para>
1735 <term><varname>PrefixDelegationHint=
</varname></term>
1737 <para>Takes an IPv6 address with prefix length as
<varname>Address=
</varname> in
1738 the
"[Network]" section. Specifies the DHCPv6 client for the requesting router to include
1739 a prefix-hint in the DHCPv6 solicitation. Prefix ranges
1-
128. Defaults to unset.
</para>
1744 <term><varname>WithoutRA=
</varname></term>
1746 <para>When true, DHCPv6 client starts without router advertisements's managed or other address configuration flag.
1747 Defaults to false.
</para>
1754 <title>[IPv6AcceptRA] Section Options
</title>
1755 <para>The
<literal>[IPv6AcceptRA]
</literal> section configures the IPv6 Router Advertisement
1756 (RA) client, if it is enabled with the
<varname>IPv6AcceptRA=
</varname> setting described
1759 <variablelist class='network-directives'
>
1761 <term><varname>UseDNS=
</varname></term>
1763 <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
1764 precedence over any statically configured ones.
</para>
1766 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
1767 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1772 <term><varname>UseDomains=
</varname></term>
1774 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1775 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
1776 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
1777 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
1778 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
1779 <literal>~
</literal>. Defaults to false.
</para>
1781 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1782 of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
1783 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1784 single-label names.
</para>
1786 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1787 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1792 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1794 <para>The table identifier for the routes received in the Router Advertisement
1795 (a number between
1 and
4294967295, or
0 to unset).
1796 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1802 <term><varname>UseAutonomousPrefix=
</varname></term>
1804 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
1805 precedence over any statically configured ones.
</para>
1810 <term><varname>UseOnLinkPrefix=
</varname></term>
1812 <para>When true (the default), the onlink prefix received in the Router Advertisement will be used and take
1813 precedence over any statically configured ones.
</para>
1818 <term><varname>BlackList=
</varname></term>
1820 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router advertisements in the list are ignored.
</para>
1825 <term><varname>DHCPv6Client=
</varname></term>
1827 <para>Takes a boolean, or the special value
<literal>always
</literal>. When true (the default), the DHCPv6 client will be started when the
1828 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
1829 managed or other information flag in the RA.
</para>
1836 <title>[DHCPServer] Section Options
</title>
1837 <para>The
<literal>[DHCPServer]
</literal> section contains
1838 settings for the DHCP server, if enabled via the
1839 <varname>DHCPServer=
</varname> option described above:
</para>
1841 <variablelist class='network-directives'
>
1844 <term><varname>PoolOffset=
</varname></term>
1845 <term><varname>PoolSize=
</varname></term>
1847 <listitem><para>Configures the pool of addresses to hand out. The pool
1848 is a contiguous sequence of IP addresses in the subnet configured for
1849 the server address, which does not include the subnet nor the broadcast
1850 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
1851 from the start of subnet, or zero to use the default value.
1852 <varname>PoolSize=
</varname> takes the number of IP addresses in the
1853 pool or zero to use the default value. By default, the pool starts at
1854 the first address after the subnet address and takes up the rest of
1855 the subnet, excluding the broadcast address. If the pool includes
1856 the server address (the default), this is reserved and not handed
1857 out to clients.
</para></listitem>
1861 <term><varname>DefaultLeaseTimeSec=
</varname></term>
1862 <term><varname>MaxLeaseTimeSec=
</varname></term>
1864 <listitem><para>Control the default and maximum DHCP lease
1865 time to pass to clients. These settings take time values in seconds or
1866 another common time unit, depending on the suffix. The default
1867 lease time is used for clients that did not ask for a specific
1868 lease time. If a client asks for a lease time longer than the
1869 maximum lease time, it is automatically shortened to the
1870 specified time. The default lease time defaults to
1h, the
1871 maximum lease time to
12h. Shorter lease times are beneficial
1872 if the configuration data in DHCP leases changes frequently
1873 and clients shall learn the new settings with shorter
1874 latencies. Longer lease times reduce the generated DHCP
1875 network traffic.
</para></listitem>
1879 <term><varname>EmitDNS=
</varname></term>
1880 <term><varname>DNS=
</varname></term>
1882 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1883 to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
1884 The DNS servers to pass to clients may be configured with the
1885 <varname>DNS=
</varname> option, which takes a list of IPv4
1886 addresses. If the
<varname>EmitDNS=
</varname> option is
1887 enabled but no servers configured, the servers are
1888 automatically propagated from an
"uplink" interface that has
1889 appropriate servers set. The
"uplink" interface is determined
1890 by the default route of the system with the highest
1891 priority. Note that this information is acquired at the time
1892 the lease is handed out, and does not take uplink interfaces
1893 into account that acquire DNS or NTP server information at a
1894 later point. DNS server propagation does not take
1895 <filename>/etc/resolv.conf
</filename> into account. Also, note
1896 that the leases are not refreshed if the uplink network
1897 configuration changes. To ensure clients regularly acquire the
1898 most current uplink DNS server information, it is thus
1899 advisable to shorten the DHCP lease time via
1900 <varname>MaxLeaseTimeSec=
</varname> described
1901 above.
</para></listitem>
1905 <term><varname>EmitNTP=
</varname></term>
1906 <term><varname>NTP=
</varname></term>
1908 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1909 <varname>DNS=
</varname> settings described above, these
1910 settings configure whether and what NTP server information
1911 shall be emitted as part of the DHCP lease. The same syntax,
1912 propagation semantics and defaults apply as for
1913 <varname>EmitDNS=
</varname> and
1914 <varname>DNS=
</varname>.
</para></listitem>
1918 <term><varname>EmitSIP=
</varname></term>
1919 <term><varname>SIP=
</varname></term>
1921 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1922 <varname>DNS=
</varname> settings described above, these
1923 settings configure whether and what SIP server information
1924 shall be emitted as part of the DHCP lease. The same syntax,
1925 propagation semantics and defaults apply as for
1926 <varname>EmitDNS=
</varname> and
1927 <varname>DNS=
</varname>.
</para></listitem>
1931 <term><varname>POP3Servers=
</varname></term>
1933 <listitem><para>Similar to the
<varname>DNS=
</varname> setting described above, this setting
1934 configures whether and what POP3 server information shall be emitted as part of the DHCP lease. The
1935 same syntax, propagation semantics and defaults apply as for
1936 <varname>DNS=
</varname>.
</para></listitem>
1940 <term><varname>SMTPServers=
</varname></term>
1942 <listitem><para>Similar to the
<varname>DNS=
</varname> setting described above, this
1943 setting configures whether and what SMTP server information shall be emitted as part of
1944 the DHCP lease. The same syntax, propagation semantics and defaults apply as for
1945 <varname>DNS=
</varname>.
</para></listitem>
1949 <term><varname>EmitRouter=
</varname></term>
1951 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
1952 setting described above, this setting configures whether the
1953 DHCP lease should contain the router option. The same syntax,
1954 propagation semantics and defaults apply as for
1955 <varname>EmitDNS=
</varname>.
</para></listitem>
1959 <term><varname>EmitTimezone=
</varname></term>
1960 <term><varname>Timezone=
</varname></term>
1962 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1963 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
1964 <varname>Timezone=
</varname> setting takes a timezone string
1965 (such as
<literal>Europe/Berlin
</literal> or
1966 <literal>UTC
</literal>) to pass to clients. If no explicit
1967 timezone is set, the system timezone of the local host is
1968 propagated, as determined by the
1969 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
1973 <term><varname>SendOption=
</varname></term>
1975 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
1976 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1977 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1978 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1979 <literal>string
</literal>. Special characters in the data string may be escaped using
1980 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1981 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1982 then all options specified earlier are cleared. Defaults to unset.
</para>
1987 <term><varname>SendVendorOption=
</varname></term>
1989 <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
1990 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1991 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1992 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1993 <literal>string
</literal>. Special characters in the data string may be escaped using
1994 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1995 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1996 then all options specified earlier are cleared. Defaults to unset.
</para>
2004 <title>[IPv6PrefixDelegation] Section Options
</title>
2005 <para>The
<literal>[IPv6PrefixDelegation]
</literal> section contains
2006 settings for sending IPv6 Router Advertisements and whether to act as
2007 a router, if enabled via the
<varname>IPv6PrefixDelegation=
</varname>
2008 option described above. IPv6 network prefixes are defined with one or
2009 more
<literal>[IPv6Prefix]
</literal> sections.
</para>
2011 <variablelist class='network-directives'
>
2014 <term><varname>Managed=
</varname></term>
2015 <term><varname>OtherInformation=
</varname></term>
2017 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
2018 addresses on the network link when
<varname>Managed=
</varname>
2019 is set to
<literal>true
</literal> or if only additional network
2020 information can be obtained via DHCPv6 for the network link when
2021 <varname>OtherInformation=
</varname> is set to
2022 <literal>true
</literal>. Both settings default to
2023 <literal>false
</literal>, which means that a DHCPv6 server is not being
2024 used.
</para></listitem>
2028 <term><varname>RouterLifetimeSec=
</varname></term>
2030 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. If set,
2031 this host also announces itself in Router Advertisements as an IPv6
2032 router for the network link. When unset, the host is not acting as a router.
</para>
2037 <term><varname>RouterPreference=
</varname></term>
2039 <listitem><para>Configures IPv6 router preference if
2040 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
2041 <literal>high
</literal>,
<literal>medium
</literal> and
2042 <literal>low
</literal>, with
<literal>normal
</literal> and
2043 <literal>default
</literal> added as synonyms for
2044 <literal>medium
</literal> just to make configuration easier. See
2045 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2046 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
2050 <term><varname>EmitDNS=
</varname></term>
2051 <term><varname>DNS=
</varname></term>
2053 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
2054 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is
2055 true.
<varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that
2056 case the IPv6 link local address is distributed. If
<varname>DNS=
</varname> is empty, DNS
2057 servers are read from the
<literal>[Network]
</literal> section. If the
2058 <literal>[Network]
</literal> section does not contain any DNS servers either, DNS servers from
2059 the uplink with the highest priority default route are used. When
<varname>EmitDNS=
</varname>
2060 is false, no DNS server information is sent in Router Advertisement messages.
2061 <varname>EmitDNS=
</varname> defaults to true.
2066 <term><varname>EmitDomains=
</varname></term>
2067 <term><varname>Domains=
</varname></term>
2069 <listitem><para>A list of DNS search domains distributed via Router
2070 Advertisement messages when
<varname>EmitDomains=
</varname> is true. If
2071 <varname>Domains=
</varname> is empty, DNS search domains are read from the
2072 <literal>[Network]
</literal> section. If the
<literal>[Network]
</literal>
2073 section does not contain any DNS search domains either, DNS search
2074 domains from the uplink with the highest priority default route are
2075 used. When
<varname>EmitDomains=
</varname> is false, no DNS search domain
2076 information is sent in Router Advertisement messages.
2077 <varname>EmitDomains=
</varname> defaults to true.
2082 <term><varname>DNSLifetimeSec=
</varname></term>
2084 <listitem><para>Lifetime in seconds for the DNS server addresses listed
2085 in
<varname>DNS=
</varname> and search domains listed in
2086 <varname>Domains=
</varname>.
</para></listitem>
2093 <title>[IPv6Prefix] Section Options
</title>
2094 <para>One or more
<literal>[IPv6Prefix]
</literal> sections contain the IPv6
2095 prefixes that are announced via Router Advertisements. See
2096 <ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink>
2097 for further details.
</para>
2099 <variablelist class='network-directives'
>
2102 <term><varname>AddressAutoconfiguration=
</varname></term>
2103 <term><varname>OnLink=
</varname></term>
2105 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
2106 autoconfigured with this prefix and whether the prefix can be used for
2107 onlink determination. Both settings default to
<literal>true
</literal>
2108 in order to ease configuration.
2113 <term><varname>Prefix=
</varname></term>
2115 <listitem><para>The IPv6 prefix that is to be distributed to hosts.
2116 Similarly to configuring static IPv6 addresses, the setting is
2117 configured as an IPv6 prefix and its prefix length, separated by a
2118 <literal>/
</literal> character. Use multiple
2119 <literal>[IPv6Prefix]
</literal> sections to configure multiple IPv6
2120 prefixes since prefix lifetimes, address autoconfiguration and onlink
2121 status may differ from one prefix to another.
</para></listitem>
2125 <term><varname>PreferredLifetimeSec=
</varname></term>
2126 <term><varname>ValidLifetimeSec=
</varname></term>
2128 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2129 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
2130 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
2131 to
2592000 seconds (
30 days).
</para></listitem>
2135 <term><varname>Assign=
</varname></term>
2136 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
2143 <title>[IPv6RoutePrefix] Section Options
</title>
2144 <para>One or more
<literal>[IPv6RoutePrefix]
</literal> sections contain the IPv6
2145 prefix routes that are announced via Router Advertisements. See
2146 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2147 for further details.
</para>
2149 <variablelist class='network-directives'
>
2152 <term><varname>Route=
</varname></term>
2154 <listitem><para>The IPv6 route that is to be distributed to hosts.
2155 Similarly to configuring static IPv6 routes, the setting is
2156 configured as an IPv6 prefix routes and its prefix route length,
2157 separated by a
<literal>/
</literal> character. Use multiple
2158 <literal>[IPv6PrefixRoutes]
</literal> sections to configure multiple IPv6
2159 prefix routes.
</para></listitem>
2163 <term><varname>LifetimeSec=
</varname></term>
2165 <listitem><para>Lifetime for the route prefix measured in
2166 seconds.
<varname>LifetimeSec=
</varname> defaults to
604800 seconds (one week).
2174 <title>[Bridge] Section Options
</title>
2175 <para>The
<literal>[Bridge]
</literal> section accepts the
2176 following keys.
</para>
2177 <variablelist class='network-directives'
>
2179 <term><varname>UnicastFlood=
</varname></term>
2181 <para>Takes a boolean. Controls whether the bridge should flood
2182 traffic for which an FDB entry is missing and the destination
2183 is unknown through this port. When unset, the kernel's default will be used.
2188 <term><varname>MulticastFlood=
</varname></term>
2190 <para>Takes a boolean. Controls whether the bridge should flood
2191 traffic for which an MDB entry is missing and the destination
2192 is unknown through this port. When unset, the kernel's default will be used.
2197 <term><varname>MulticastToUnicast=
</varname></term>
2199 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2200 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2201 When unset, the kernel's default will be used.
2206 <term><varname>NeighborSuppression=
</varname></term>
2208 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2209 this port. When unset, the kernel's default will be used.
2214 <term><varname>Learning=
</varname></term>
2216 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2217 this port. When unset, the kernel's default will be used.
2222 <term><varname>HairPin=
</varname></term>
2224 <para>Takes a boolean. Configures whether traffic may be sent back
2225 out of the port on which it was received. When this flag is false, and the bridge
2226 will not forward traffic back out of the receiving port.
2227 When unset, the kernel's default will be used.
</para>
2231 <term><varname>UseBPDU=
</varname></term>
2233 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2234 processed by the bridge port. When unset, the kernel's default will be used.
</para>
2238 <term><varname>FastLeave=
</varname></term>
2240 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2241 traffic on a port that receives an IGMP Leave message. It is only used with
2242 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
2246 <term><varname>AllowPortToBeRoot=
</varname></term>
2248 <para>Takes a boolean. Configures whether a given port is allowed to
2249 become a root port. Only used when STP is enabled on the bridge.
2250 When unset, the kernel's default will be used.
</para>
2254 <term><varname>ProxyARP=
</varname></term>
2256 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2257 When unset, the kernel's default will be used.
</para>
2261 <term><varname>ProxyARPWiFi=
</varname></term>
2263 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2264 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
2265 When unset, the kernel's default will be used.
</para>
2269 <term><varname>MulticastRouter=
</varname></term>
2271 <para>Configures this port for having multicast routers attached. A port with a multicast
2272 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
2273 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
2274 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
2275 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
2276 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
2280 <term><varname>Cost=
</varname></term>
2282 <para>Sets the
"cost" of sending packets of this interface.
2283 Each port in a bridge may have a different speed and the cost
2284 is used to decide which link to use. Faster interfaces
2285 should have lower costs. It is an integer value between
1 and
2290 <term><varname>Priority=
</varname></term>
2292 <para>Sets the
"priority" of sending packets on this interface.
2293 Each port in a bridge may have a different priority which is used
2294 to decide which link to use. Lower value means higher priority.
2295 It is an integer value between
0 to
63. Networkd does not set any
2296 default, meaning the kernel default value of
32 is used.
</para>
2302 <title>[BridgeFDB] Section Options
</title>
2303 <para>The
<literal>[BridgeFDB]
</literal> section manages the
2304 forwarding database table of a port and accepts the following
2305 keys. Specify several
<literal>[BridgeFDB]
</literal> sections to
2306 configure several static MAC table entries.
</para>
2308 <variablelist class='network-directives'
>
2310 <term><varname>MACAddress=
</varname></term>
2312 <para>As in the
<literal>[Network]
</literal> section. This
2313 key is mandatory.
</para>
2317 <term><varname>Destination=
</varname></term>
2319 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
2323 <term><varname>VLANId=
</varname></term>
2325 <para>The VLAN ID for the new static MAC table entry. If
2326 omitted, no VLAN ID information is appended to the new static MAC
2331 <term><varname>VNI=
</varname></term>
2333 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2334 the remote VXLAN tunnel endpoint. Takes a number in the range
1-
16777215.
2335 Defaults to unset.
</para>
2339 <term><varname>AssociatedWith=
</varname></term>
2341 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
2342 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
2343 <literal>use
</literal> means the address is in use. User space can use this option to
2344 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
2345 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
2346 means the address is associated with master devices fdb.
<literal>router
</literal> means
2347 the destination address is associated with a router. Note that it's valid if the referenced
2348 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
2355 <title>[LLDP] Section Options
</title>
2356 <para>The
<literal>[LLDP]
</literal> section manages the Link Layer Discovery Protocol (LLDP) and accepts the
2357 following keys.
</para>
2358 <variablelist class='network-directives'
>
2360 <term><varname>MUDURL=
</varname></term>
2362 <para>Controls support for Ethernet LLDP packet's Manufacturer Usage Description (MUD). MUD is an embedded software
2363 standard defined by the IETF that allows IoT Device makers to advertise device specifications, including the intended
2364 communication patterns for their device when it connects to the network. The network can then use this intent to author
2365 a context-specific access policy, so the device functions only within those parameters. Takes an URL of length up to
255
2366 characters. A superficial verification that the string is a valid URL
2367 will be performed. See
2368 <ulink url=
"https://tools.ietf.org/html/rfc8520">RFC
8520</ulink> for details. The MUD URL received
2369 from the LLDP packets will be saved at the state files and can be read via
2370 <function>sd_lldp_neighbor_get_mud_url()
</function> function.
</para>
2377 <title>[CAN] Section Options
</title>
2378 <para>The
<literal>[CAN]
</literal> section manages the Controller Area Network (CAN bus) and accepts the
2379 following keys.
</para>
2380 <variablelist class='network-directives'
>
2382 <term><varname>BitRate=
</varname></term>
2384 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
2385 be used here. Takes a number in the range
1.
.4294967295.
</para>
2389 <term><varname>SamplePoint=
</varname></term>
2391 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2392 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2396 <term><varname>DataBitRate=
</varname></term>
2397 <term><varname>DataSamplePoint=
</varname></term>
2399 <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
2400 analogous to the
<varname>BitRate=
</varname> and
<varname>SamplePoint=
</varname> keys.
</para>
2404 <term><varname>FDMode=
</varname></term>
2406 <para>Takes a boolean. When
<literal>yes
</literal>, CAN-FD mode is enabled for the interface.
2407 Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
2408 the
<varname>DataBitRate=
</varname> and
<varname>DataSamplePoint=
</varname> keys.
</para>
2412 <term><varname>FDNonISO=
</varname></term>
2414 <para>Takes a boolean. When
<literal>yes
</literal>, non-ISO CAN-FD mode is enabled for the
2415 interface. When unset, the kernel's default will be used.
</para>
2419 <term><varname>RestartSec=
</varname></term>
2421 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2422 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2423 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2424 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2425 automatic restart off. By default automatic restart is disabled.
</para>
2429 <term><varname>Termination=
</varname></term>
2431 <para>Takes a boolean. When
<literal>yes
</literal>, the termination resistor will be selected for
2432 the bias network. When unset, the kernel's default will be used.
</para>
2436 <term><varname>TripleSampling=
</varname></term>
2438 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2439 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
2443 <term><varname>ListenOnly=
</varname></term>
2445 <para>Takes a boolean. When
<literal>yes
</literal>, listen-only mode is enabled. When the
2446 interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
2447 bit. Listen-only mode is important to debug CAN networks without interfering with the
2448 communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
2456 <title>[QDisc] Section Options
</title>
2457 <para>The
<literal>[QDisc]
</literal> section manages the traffic control queueing discipline (qdisc).
</para>
2459 <variablelist class='network-directives'
>
2461 <term><varname>Parent=
</varname></term>
2463 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
2464 or
<literal>ingress
</literal>. This is mandatory.
</para>
2468 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2473 <title>[NetworkEmulator] Section Options
</title>
2474 <para>The
<literal>[NetworkEmulator]
</literal> section manages the queueing discipline (qdisc) of
2475 the network emulator. It can be used to configure the kernel packet scheduler and simulate packet
2476 delay and loss for UDP or TCP applications, or limit the bandwidth usage of a particular service to
2477 simulate internet connections.
</para>
2479 <variablelist class='network-directives'
>
2480 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2481 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2484 <term><varname>DelaySec=
</varname></term>
2486 <para>Specifies the fixed amount of delay to be added to all packets going out of the
2487 interface. Defaults to unset.
</para>
2492 <term><varname>DelayJitterSec=
</varname></term>
2494 <para>Specifies the chosen delay to be added to the packets outgoing to the network
2495 interface. Defaults to unset.
</para>
2500 <term><varname>PacketLimit=
</varname></term>
2502 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
2503 An unsigned integer ranges
0 to
4294967294. Defaults to
1000.
</para>
2508 <term><varname>LossRate=
</varname></term>
2510 <para>Specifies an independent loss probability to be added to the packets outgoing from the
2511 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2516 <term><varname>DuplicateRate=
</varname></term>
2518 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
2519 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2526 <title>[TokenBucketFilter] Section Options
</title>
2527 <para>The
<literal>[TokenBucketFilter]
</literal> section manages the queueing discipline (qdisc) of
2528 token bucket filter (tbf).
</para>
2530 <variablelist class='network-directives'
>
2531 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2532 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2535 <term><varname>LatencySec=
</varname></term>
2537 <para>Specifies the latency parameter, which specifies the maximum amount of time a
2538 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
2543 <term><varname>LimitSize=
</varname></term>
2545 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
2546 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
2547 respectively, to the base of
1000. Defaults to unset.
</para>
2552 <term><varname>Burst=
</varname></term>
2554 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
2555 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
2556 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to
2562 <term><varname>Rate=
</varname></term>
2564 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
2565 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
2566 Defaults to unset.
</para>
2571 <term><varname>MPUBytes=
</varname></term>
2573 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
2574 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2575 Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to zero.
</para>
2580 <term><varname>PeakRate=
</varname></term>
2582 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
2583 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2584 1000. Defaults to unset.
</para>
2589 <term><varname>MTUBytes=
</varname></term>
2591 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
2592 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000.
2593 Defaults to unset.
</para>
2600 <title>[PIE] Section Options
</title>
2601 <para>The
<literal>[PIE]
</literal> section manages the queueing discipline
2602 (qdisc) of Proportional Integral controller-Enhanced (PIE).
</para>
2604 <variablelist class='network-directives'
>
2605 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2606 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2609 <term><varname>PacketLimit=
</varname></term>
2611 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2612 dropped. An unsigned integer ranges
1 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2619 <title>[StochasticFairBlue] Section Options
</title>
2620 <para>The
<literal>[StochasticFairBlue]
</literal> section manages the queueing discipline
2621 (qdisc) of stochastic fair blue (sfb).
</para>
2623 <variablelist class='network-directives'
>
2624 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2625 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2628 <term><varname>PacketLimit=
</varname></term>
2630 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2631 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2638 <title>[StochasticFairnessQueueing] Section Options
</title>
2639 <para>The
<literal>[StochasticFairnessQueueing]
</literal> section manages the queueing discipline
2640 (qdisc) of stochastic fairness queueing (sfq).
</para>
2642 <variablelist class='network-directives'
>
2643 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2644 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2647 <term><varname>PerturbPeriodSec=
</varname></term>
2649 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
2656 <title>[BFIFO] Section Options
</title>
2657 <para>The
<literal>[BFIFO]
</literal> section manages the queueing discipline (qdisc) of
2658 Byte limited Packet First In First Out (bfifo).
</para>
2660 <variablelist class='network-directives'
>
2661 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2662 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2665 <term><varname>LimitSize=
</varname></term>
2667 <para>Specifies the hard limit on the FIFO size in bytes. The size limit (a buffer size) to prevent it
2668 from overflowing in case it is unable to dequeue packets as quickly as it receives them. When this limit
2669 is reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed as
2670 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2677 <title>[PFIFO] Section Options
</title>
2678 <para>The
<literal>[PFIFO]
</literal> section manages the queueing discipline (qdisc) of
2679 Packet First In First Out (pfifo).
</para>
2681 <variablelist class='network-directives'
>
2682 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2683 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2686 <term><varname>PacketLimit=
</varname></term>
2688 <para>Specifies the hard limit on the FIFO size in number of packets. The size limit (a buffer size) to prevent it
2689 from overflowing in case it is unable to dequeue packets as quickly as it receives them. When this limit is reached,
2690 incoming packets are dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2697 <title>[PFIFOHeadDrop] Section Options
</title>
2698 <para>The
<literal>[PFIFOHeadDrop]
</literal> section manages the queueing discipline (qdisc) of
2699 Packet First In First Out Head Drop (pfifo_head_drop).
</para>
2701 <variablelist class='network-directives'
>
2702 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2703 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2706 <term><varname>PacketLimit=
</varname></term>
2708 <para>As in
<literal>[PFIFO]
</literal> section.
</para></listitem>
2714 <title>[PFIFOFast] Section Options
</title>
2715 <para>The
<literal>[PFIFOFast]
</literal> section manages the queueing discipline (qdisc) of
2716 Packet First In First Out Fast (pfifo_fast).
</para>
2718 <variablelist class='network-directives'
>
2719 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2720 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2725 <title>[CAKE] Section Options
</title>
2726 <para>The
<literal>[CAKE]
</literal> section manages the queueing discipline (qdisc) of
2727 Common Applications Kept Enhanced (CAKE).
</para>
2729 <variablelist class='network-directives'
>
2730 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2731 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2734 <term><varname>Overhead=
</varname></term>
2736 <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative.
2737 Takes an integer ranges -
64 to
256. Defaults to unset and kernel's default is used.
</para>
2742 <term><varname>Bandwidth=
</varname></term>
2744 <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
2745 parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to
2746 unset and kernel's default is used.
</para>
2753 <title>[ControlledDelay] Section Options
</title>
2754 <para>The
<literal>[ControlledDelay]
</literal> section manages the queueing discipline (qdisc) of
2755 controlled delay (CoDel).
</para>
2757 <variablelist class='network-directives'
>
2758 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2759 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2762 <term><varname>PacketLimit=
</varname></term>
2764 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2765 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2770 <term><varname>TargetSec=
</varname></term>
2772 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2773 Defaults to unset and kernel's default is used.
</para>
2778 <term><varname>IntervalSec=
</varname></term>
2780 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2781 become too stale. Defaults to unset and kernel's default is used.
</para>
2786 <term><varname>ECN=
</varname></term>
2788 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2789 unset and kernel's default is used.
</para>
2794 <term><varname>CEThresholdSec=
</varname></term>
2796 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2797 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2804 <title>[DeficitRoundRobinScheduler] Section Options
</title>
2805 <para>The
<literal>[DeficitRoundRobinScheduler]
</literal> section manages the queueing discipline (qdisc) of
2806 Deficit Round Robin Scheduler (DRR).
</para>
2808 <variablelist class='network-directives'
>
2809 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2810 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2815 <title>[DeficitRoundRobinSchedulerClass] Section Options
</title>
2816 <para>The
<literal>[DeficitRoundRobinSchedulerClass]
</literal> section manages the traffic control class of
2817 Deficit Round Robin Scheduler (DRR).
</para>
2819 <variablelist class='network-directives'
>
2820 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
2821 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
2824 <term><varname>Quantum=
</varname></term>
2826 <para>Specifies the amount of bytes a flow is allowed to dequeue before the
2827 scheduler moves to the next class. An unsigned integer ranges
1 to
4294967294.
2828 Defaults to the MTU of the interface.
</para>
2836 <title>[GenericRandomEarlyDetection] Section Options
</title>
2837 <para>The
<literal>[GenericRandomEarlyDetection]
</literal> section manages the queueing discipline
2838 (qdisc) of Generic Random Early Detection (GRED).
</para>
2840 <variablelist class='network-directives'
>
2841 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2842 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2845 <term><varname>VirtualQueues=
</varname></term>
2847 <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>
2852 <term><varname>DefaultVirtualQueue=
</varname></term>
2854 <para>Specifies the number of default virtual queue. This must be less than
<varname>VirtualQueue=
</varname>.
2855 Defaults to unset and kernel's default is used.
</para>
2860 <term><varname>GenericRIO=
</varname></term>
2862 <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
2863 unset and kernel's default is used.
</para>
2870 <title>[FairQueueingControlledDelay] Section Options
</title>
2871 <para>The
<literal>[FairQueueingControlledDelay]
</literal> section manages the queueing discipline
2872 (qdisc) of fair queuing controlled delay (FQ-CoDel).
</para>
2874 <variablelist class='network-directives'
>
2875 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2876 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2879 <term><varname>PacketLimit=
</varname></term>
2881 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2882 dropped. Defaults to unset and kernel's default is used.
</para>
2887 <term><varname>MemoryLimit=
</varname></term>
2889 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
2890 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2891 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2896 <term><varname>Flows=
</varname></term>
2898 <para>Specifies the number of flows into which the incoming packets are classified.
2899 Defaults to unset and kernel's default is used.
</para>
2904 <term><varname>TargetSec=
</varname></term>
2906 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2907 Defaults to unset and kernel's default is used.
</para>
2912 <term><varname>IntervalSec=
</varname></term>
2914 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2915 become too stale. Defaults to unset and kernel's default is used.
</para>
2920 <term><varname>Quantum=
</varname></term>
2922 <para>Specifies the number of bytes used as 'deficit' in the fair queuing algorithmtimespan.
2923 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2924 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2929 <term><varname>ECN=
</varname></term>
2931 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2932 unset and kernel's default is used.
</para>
2937 <term><varname>CEThresholdSec=
</varname></term>
2939 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2940 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2947 <title>[FairQueueing] Section Options
</title>
2948 <para>The
<literal>[FairQueueing]
</literal> section manages the queueing discipline
2949 (qdisc) of fair queue traffic policing (FQ).
</para>
2951 <variablelist class='network-directives'
>
2952 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
2953 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
2956 <term><varname>PacketLimit=
</varname></term>
2958 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2959 dropped. Defaults to unset and kernel's default is used.
</para>
2964 <term><varname>FlowLimit=
</varname></term>
2966 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
2967 unset and kernel's default is used.
</para>
2972 <term><varname>Quantum=
</varname></term>
2974 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
2975 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2976 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
2977 default is used.
</para>
2982 <term><varname>InitialQuantum=
</varname></term>
2984 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
2985 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
2986 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
2987 kernel's default is used.
</para>
2992 <term><varname>MaximumRate=
</varname></term>
2994 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
2995 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2996 1000. Defaults to unset and kernel's default is used.
</para>
3001 <term><varname>Buckets=
</varname></term>
3003 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
3004 kernel's default is used.
</para>
3009 <term><varname>OrphanMask=
</varname></term>
3011 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
3012 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
3013 kernel's default is used.
</para>
3018 <term><varname>Pacing=
</varname></term>
3020 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
3021 default is used.
</para>
3026 <term><varname>CEThresholdSec=
</varname></term>
3028 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
3029 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
3036 <title>[TrivialLinkEqualizer] Section Options
</title>
3037 <para>The
<literal>[TrivialLinkEqualizer]
</literal> section manages the queueing discipline (qdisc) of
3038 trivial link equalizer (teql).
</para>
3040 <variablelist class='network-directives'
>
3041 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3042 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3045 <term><varname>Id=
</varname></term>
3047 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
3048 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
3049 <constant>max_equalizers=N+
1</constant> option must be loaded before
3050 <command>systemd-networkd
</command> is started.
</para>
3057 <title>[HierarchyTokenBucket] Section Options
</title>
3058 <para>The
<literal>[HierarchyTokenBucket]
</literal> section manages the queueing discipline (qdisc) of
3059 hierarchy token bucket (htb).
</para>
3061 <variablelist class='network-directives'
>
3062 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3063 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3066 <term><varname>DefaultClass=
</varname></term>
3068 <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
3069 to the class. Defaults to unset.
</para>
3076 <title>[HierarchyTokenBucketClass] Section Options
</title>
3077 <para>The
<literal>[HierarchyTokenBucketClass]
</literal> section manages the traffic control class of
3078 hierarchy token bucket (htb).
</para>
3080 <variablelist class='network-directives'
>
3081 <xi:include href=
"tc.xml" xpointer=
"tclass-parent" />
3082 <xi:include href=
"tc.xml" xpointer=
"tclass-classid" />
3085 <term><varname>Priority=
</varname></term>
3087 <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
3088 priority field are tried for packets first. This setting is mandatory.
</para>
3093 <term><varname>Rate=
</varname></term>
3095 <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
3096 with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
3097 to the base of
1000. This setting is mandatory.
</para>
3102 <term><varname>CeilRate=
</varname></term>
3104 <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
3105 When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
3106 respectively, to the base of
1000. When unset, the value specified with
<varname>Rate=
</varname>
3114 <title>[HeavyHitterFilter] Section Options
</title>
3115 <para>The
<literal>[HeavyHitterFilter]
</literal> section manages the queueing discipline
3116 (qdisc) of Heavy Hitter Filter (hhf).
</para>
3118 <variablelist class='network-directives'
>
3119 <xi:include href=
"tc.xml" xpointer=
"qdisc-parent" />
3120 <xi:include href=
"tc.xml" xpointer=
"qdisc-handle" />
3123 <term><varname>PacketLimit=
</varname></term>
3125 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
3126 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
3133 <title>[BridgeVLAN] Section Options
</title>
3134 <para>The
<literal>[BridgeVLAN]
</literal> section manages the VLAN ID configuration of a bridge port and accepts
3135 the following keys. Specify several
<literal>[BridgeVLAN]
</literal> sections to configure several VLAN entries.
3136 The
<varname>VLANFiltering=
</varname> option has to be enabled, see
<literal>[Bridge]
</literal> section in
3137 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
3139 <variablelist class='network-directives'
>
3141 <term><varname>VLAN=
</varname></term>
3143 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
3144 from
1 to
4094.
</para>
3148 <term><varname>EgressUntagged=
</varname></term>
3150 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
3151 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
3152 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
3156 <term><varname>PVID=
</varname></term>
3158 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
3159 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
3160 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
3167 <title>Examples
</title>
3169 <title>Static network configuration
</title>
3171 <programlisting># /etc/systemd/network/
50-static.network
3176 Address=
192.168.0.15/
24
3177 Gateway=
192.168.0.1</programlisting>
3179 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
3180 specified gateway will be used for a default route.
</para>
3184 <title>DHCP on ethernet links
</title>
3186 <programlisting># /etc/systemd/network/
80-dhcp.network
3191 DHCP=yes
</programlisting>
3193 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
3194 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
3198 <title>IPv6 Prefix Delegation
</title>
3200 <programlisting># /etc/systemd/network/
55-ipv6-pd-upstream.network
3205 DHCP=ipv6
</programlisting>
3207 <programlisting># /etc/systemd/network/
56-ipv6-pd-downstream.network
3212 IPv6PrefixDelegation=dhcpv6
</programlisting>
3214 <para>This will enable IPv6 PD on the interface enp1s0 as an upstream interface where the
3215 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
</para>
3219 <title>A bridge with two enslaved links
</title>
3221 <programlisting># /etc/systemd/network/
25-bridge-static.network
3226 Address=
192.168.0.15/
24
3228 DNS=
192.168.0.1</programlisting>
3230 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
3235 Bridge=bridge0
</programlisting>
3237 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
3242 Bridge=bridge0
</programlisting>
3244 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
3245 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
3246 and network assigned, and a default route via the specified gateway will be
3247 added. The specified DNS server will be added to the global list of DNS resolvers.
3255 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
3271 EgressUntagged=
300-
400</programlisting>
3273 <para>This overrides the configuration specified in the previous example for the
3274 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
3275 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
3276 untagged when they leave on this interface. Untagged packets which arrive on this
3277 interface will be assigned VLAN ID
42.
</para>
3281 <title>Various tunnels
</title>
3283 <programlisting>/etc/systemd/network/
25-tunnels.network
3294 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
3300 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
3306 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
3312 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
3318 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
3319 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
3323 <title>A bond device
</title>
3325 <programlisting># /etc/systemd/network/
30-bond1.network
3333 <programlisting># /etc/systemd/network/
30-bond1.netdev
3339 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
3341 MACAddress=
52:
54:
00:e9:
64:
41
3347 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
3349 MACAddress=
52:
54:
00:e9:
64:
42
3355 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
3356 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
3357 will be used to acquire an address.
</para>
3361 <title>Virtual Routing and Forwarding (VRF)
</title>
3362 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
3363 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
3364 within the routing table defined during VRF creation. For kernels before
4.8 traffic
3365 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
3367 <programlisting># /etc/systemd/network/
25-vrf.network
3377 <title>MacVTap
</title>
3378 <para>This brings up a network interface
<literal>macvtap-test
</literal>
3379 and attaches it to
<literal>enp0s25
</literal>.
</para>
3380 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
3385 MACVTAP=macvtap-test
3390 <title>A Xfrm interface with physical underlying device.
</title>
3392 <programlisting># /etc/systemd/network/
27-xfrm.netdev
3397 InterfaceId=
7</programlisting>
3399 <programlisting># /etc/systemd/network/
27-eth0.network
3404 Xfrm=xfrm0
</programlisting>
3406 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
3407 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
3408 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
3414 <title>See Also
</title>
3416 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
3417 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
3418 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3419 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3420 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
projects / thirdparty / systemd.git / blob