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 host name, 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
463 <term><varname>BindCarrier=
</varname></term>
465 <para>A link name or a list of link names. When set, controls the behavior of the current
466 link. When all links in the list are in an operational down state, the current link is brought
467 down. When at least one link has carrier, the current interface is brought up.
472 <term><varname>Address=
</varname></term>
474 <para>A static IPv4 or IPv6 address and its prefix length,
475 separated by a
<literal>/
</literal> character. Specify
476 this key more than once to configure several addresses.
477 The format of the address must be as described in
478 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
479 This is a short-hand for an [Address] section only
480 containing an Address key (see below). This option may be
481 specified more than once.
484 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
485 (for IPv6), a new address range of the requested size is automatically allocated from a
486 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
487 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
488 all known network configuration files to avoid address range conflicts. The default system-wide
489 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.
490 This functionality is useful to manage a large number of dynamically created network interfaces
491 with the same network configuration and automatic address range assignment.
</para>
496 <term><varname>Gateway=
</varname></term>
498 <para>The gateway address, which must be in the format
500 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
501 This is a short-hand for a [Route] section only containing
502 a Gateway key. This option may be specified more than
507 <term><varname>DNS=
</varname></term>
509 <para>A DNS server address, which must be in the format
511 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
512 This option may be specified more than once. This setting is read by
513 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
517 <term><varname>Domains=
</varname></term>
519 <para>A whitespace-separated list of domains which should be resolved using the DNS servers on
520 this link. Each item in the list should be a domain name, optionally prefixed with a tilde
521 (
<literal>~
</literal>). The domains with the prefix are called
"routing-only domains". The
522 domains without the prefix are called
"search domains" and are first used as search suffixes for
523 extending single-label host names (host names containing no dots) to become fully qualified
524 domain names (FQDNs). If a single-label host name is resolved on this interface, each of the
525 specified search domains are appended to it in turn, converting it into a fully qualified domain
526 name, until one of them may be successfully resolved.
</para>
528 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for host names
529 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
530 the DNS servers configured for this interface. The domain routing logic is particularly useful on
531 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
533 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
534 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
535 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
536 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
537 if a link on which they are connected is available.
</para>
539 <para>This setting is read by
540 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
541 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
542 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
543 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
544 name servers limited to a specific link.
</para>
548 <term><varname>DNSDefaultRoute=
</varname></term>
550 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
551 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
552 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
553 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
554 queries not matching any link's configured domains will be routed to this link if it has no routing-only
555 domains configured.
</para>
559 <term><varname>NTP=
</varname></term>
561 <para>An NTP server address. This option may be specified more than once. This setting is read by
562 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
566 <term><varname>IPForward=
</varname></term>
567 <listitem><para>Configures IP packet forwarding for the
568 system. If enabled, incoming packets on any network
569 interface will be forwarded to any other interfaces
570 according to the routing table. Takes a boolean,
571 or the values
<literal>ipv4
</literal> or
572 <literal>ipv6
</literal>, which only enable IP packet
573 forwarding for the specified address family. This controls
574 the
<filename>net.ipv4.ip_forward
</filename> and
575 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
576 options of the network interface (see
<ulink
577 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
578 for details about sysctl options). Defaults to
579 <literal>no
</literal>.
</para>
581 <para>Note: this setting controls a global kernel option,
582 and does so one way only: if a network that has this setting
583 enabled is set up the global setting is turned on. However,
584 it is never turned off again, even after all networks with
585 this setting enabled are shut down again.
</para>
587 <para>To allow IP packet forwarding only between specific
588 network interfaces use a firewall.
</para>
592 <term><varname>IPMasquerade=
</varname></term>
593 <listitem><para>Configures IP masquerading for the network
594 interface. If enabled, packets forwarded from the network
595 interface will be appear as coming from the local host.
596 Takes a boolean argument. Implies
597 <varname>IPForward=ipv4
</varname>. Defaults to
598 <literal>no
</literal>.
</para></listitem>
601 <term><varname>IPv6PrivacyExtensions=
</varname></term>
602 <listitem><para>Configures use of stateless temporary
603 addresses that change over time (see
<ulink
604 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
605 Privacy Extensions for Stateless Address Autoconfiguration
606 in IPv6). Takes a boolean or the special values
607 <literal>prefer-public
</literal> and
608 <literal>kernel
</literal>. When true, enables the privacy
609 extensions and prefers temporary addresses over public
610 addresses. When
<literal>prefer-public
</literal>, enables the
611 privacy extensions, but prefers public addresses over
612 temporary addresses. When false, the privacy extensions
613 remain disabled. When
<literal>kernel
</literal>, the kernel's
614 default setting will be left in place. Defaults to
615 <literal>no
</literal>.
</para></listitem>
618 <term><varname>IPv6AcceptRA=
</varname></term>
619 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
620 interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they may
621 trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or if no
622 routers are found on the link. The default is to disable RA reception for bridge devices or when IP
623 forwarding is enabled, and to enable it otherwise. Cannot be enabled on bond devices and when link
624 local adressing is disabled.
</para>
626 <para>Further settings for the IPv6 RA support may be configured in the
627 <literal>[IPv6AcceptRA]
</literal> section, see below.
</para>
629 <para>Also see
<ulink
630 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink> in the kernel
631 documentation regarding
<literal>accept_ra
</literal>, but note that systemd's setting of
632 <constant>1</constant> (i.e. true) corresponds to kernel's setting of
<constant>2</constant>.
</para>
634 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
635 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
636 RA protocol is used, and the kernel's own implementation remains disabled, since
637 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
638 and these are not available from the kernel if the kernel's own implementation is used.
</para>
642 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
643 <listitem><para>Configures the amount of IPv6 Duplicate
644 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
648 <term><varname>IPv6HopLimit=
</varname></term>
649 <listitem><para>Configures IPv6 Hop Limit. For each router that
650 forwards the packet, the hop limit is decremented by
1. When the
651 hop limit field reaches zero, the packet is discarded.
652 When unset, the kernel's default will be used.
656 <term><varname>IPv4ProxyARP=
</varname></term>
657 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
658 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
659 the router accepts responsibility for routing packets to the
"real" destination. (see
<ulink
660 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
661 When unset, the kernel's default will be used.
665 <term><varname>IPv6ProxyNDP=
</varname></term>
666 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
667 Protocol) is a technique for IPv6 to allow routing of addresses to a different
668 destination when peers expect them to be present on a certain physical link.
669 In this case a router answers Neighbour Advertisement messages intended for
670 another machine by offering its own MAC address as destination.
671 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
672 Advertisement messages for addresses in the IPv6 neighbor proxy table,
673 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
674 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
675 interface depending on this option.
676 When unset, the kernel's default will be used.
680 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
681 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
682 proxied. This option may be specified more than once. systemd-networkd will add the
683 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
684 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
685 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
689 <term><varname>IPv6PrefixDelegation=
</varname></term>
690 <listitem><para>Whether to enable or disable Router Advertisement sending on a link.
691 Allowed values are
<literal>static
</literal> which distributes prefixes as defined in
692 the
<literal>[IPv6PrefixDelegation]
</literal> and any
<literal>[IPv6Prefix]
</literal>
693 sections,
<literal>dhcpv6
</literal> which requests prefixes using a DHCPv6 client
694 configured for another link and any values configured in the
695 <literal>[IPv6PrefixDelegation]
</literal> section while ignoring all static prefix
696 configuration sections,
<literal>yes
</literal> which uses both static configuration
697 and DHCPv6, and
<literal>false
</literal> which turns off IPv6 prefix delegation
698 altogether. Defaults to
<literal>false
</literal>. See the
699 <literal>[IPv6PrefixDelegation]
</literal> and the
<literal>[IPv6Prefix]
</literal>
700 sections for more configuration options.
704 <term><varname>IPv6MTUBytes=
</varname></term>
705 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
706 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
710 <term><varname>Bridge=
</varname></term>
712 <para>The name of the bridge to add the link to. See
713 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
718 <term><varname>Bond=
</varname></term>
720 <para>The name of the bond to add the link to. See
721 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
726 <term><varname>VRF=
</varname></term>
728 <para>The name of the VRF to add the link to. See
729 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
734 <term><varname>VLAN=
</varname></term>
736 <para>The name of a VLAN to create on the link. See
737 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
738 This option may be specified more than once.
</para>
742 <term><varname>IPVLAN=
</varname></term>
744 <para>The name of a IPVLAN to create on the link. See
745 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
746 This option may be specified more than once.
</para>
750 <term><varname>MACVLAN=
</varname></term>
752 <para>The name of a MACVLAN to create on the link. See
753 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
754 This option may be specified more than once.
</para>
758 <term><varname>VXLAN=
</varname></term>
760 <para>The name of a VXLAN to create on the link. See
761 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
762 This option may be specified more than once.
</para>
766 <term><varname>Tunnel=
</varname></term>
768 <para>The name of a Tunnel to create on the link. See
769 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
770 This option may be specified more than once.
</para>
774 <term><varname>MACsec=
</varname></term>
776 <para>The name of a MACsec device to create on the link. See
777 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
778 This option may be specified more than once.
</para>
782 <term><varname>ActiveSlave=
</varname></term>
784 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
785 option is only valid for following modes:
786 <literal>active-backup
</literal>,
787 <literal>balance-alb
</literal> and
788 <literal>balance-tlb
</literal>. Defaults to false.
793 <term><varname>PrimarySlave=
</varname></term>
795 <para>Takes a boolean. Specifies which slave is the primary device. The specified
796 device will always be the active slave while it is available. Only when the
797 primary is off-line will alternate devices be used. This is useful when
798 one slave is preferred over another, e.g. when one slave has higher throughput
799 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
801 <literal>active-backup
</literal>,
802 <literal>balance-alb
</literal> and
803 <literal>balance-tlb
</literal>. Defaults to false.
808 <term><varname>ConfigureWithoutCarrier=
</varname></term>
810 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
816 <term><varname>IgnoreCarrierLoss=
</varname></term>
818 <para>A boolean. Allows networkd to retain both the static and dynamic configuration of the
819 interface even if its carrier is lost. Defaults to false.
824 <term><varname>Xfrm=
</varname></term>
826 <para>The name of the xfrm to create on the link. See
827 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
828 This option may be specified more than once.
</para>
832 <term><varname>KeepConfiguration=
</varname></term>
834 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
835 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
836 will not drop static addresses and routes on starting up process. When set to
837 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
838 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
839 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
840 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
841 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
842 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
843 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
<literal>no
</literal>.
853 <title>[Address] Section Options
</title>
855 <para>An
<literal>[Address]
</literal> section accepts the
856 following keys. Specify several
<literal>[Address]
</literal>
857 sections to configure several addresses.
</para>
859 <variablelist class='network-directives'
>
861 <term><varname>Address=
</varname></term>
863 <para>As in the
<literal>[Network]
</literal> section. This key is mandatory. Each
864 <literal>[Address]
</literal> section can contain one
<varname>Address=
</varname> setting.
</para>
868 <term><varname>Peer=
</varname></term>
870 <para>The peer address in a point-to-point connection.
871 Accepts the same format as the
<varname>Address=
</varname>
876 <term><varname>Broadcast=
</varname></term>
878 <para>The broadcast address, which must be in the format
880 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
881 This key only applies to IPv4 addresses. If it is not
882 given, it is derived from the
<varname>Address=
</varname>
887 <term><varname>Label=
</varname></term>
889 <para>An address label.
</para>
893 <term><varname>PreferredLifetime=
</varname></term>
895 <para>Allows the default
"preferred lifetime" of the address to be overridden.
896 Only three settings are accepted:
<literal>forever
</literal> or
<literal>infinity
</literal>
897 which is the default and means that the address never expires, and
<literal>0</literal> which means
898 that the address is considered immediately
"expired" and will not be used,
899 unless explicitly requested. A setting of PreferredLifetime=
0 is useful for
900 addresses which are added to be used only by a specific application,
901 which is then configured to use them explicitly.
</para>
905 <term><varname>Scope=
</varname></term>
907 <para>The scope of the address, which can be
<literal>global
</literal>,
908 <literal>link
</literal> or
<literal>host
</literal> or an unsigned integer ranges
0 to
255.
909 Defaults to
<literal>global
</literal>.
</para>
913 <term><varname>HomeAddress=
</varname></term>
915 <para>Takes a boolean. Designates this address the
"home address" as defined in
916 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
917 Supported only on IPv6. Defaults to false.
</para>
921 <term><varname>DuplicateAddressDetection=
</varname></term>
923 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
924 <literal>both
</literal>,
<literal>none
</literal>. When
<literal>ipv4
</literal>,
925 performs IPv4 Duplicate Address Detection. See
926 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
927 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
928 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>.
929 Defaults to
<literal>ipv6
</literal>.
</para>
933 <term><varname>ManageTemporaryAddress=
</varname></term>
935 <para>Takes a boolean. If true the kernel manage temporary addresses created
936 from this one as template on behalf of Privacy Extensions
937 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
938 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
939 The given address needs to have a prefix length of
64. This flag allows using privacy
940 extensions in a manually configured network, just like if stateless auto-configuration
941 was active. Defaults to false.
</para>
945 <term><varname>AddPrefixRoute=
</varname></term>
947 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
948 Defaults to true.
</para>
952 <term><varname>AutoJoin=
</varname></term>
954 <para>Takes a boolean. Joining multicast group on ethernet level via
955 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
956 IGMP snooping since the switch would not replicate multicast packets on ports that did not
957 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
958 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
959 that enables then to do the required join. By extending ip address command with option
960 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
961 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
962 Defaults to
<literal>no
</literal>.
</para>
969 <title>[Neighbor] Section Options
</title>
970 <para>A
<literal>[Neighbor]
</literal> section accepts the
971 following keys. The neighbor section adds a permanent, static
972 entry to the neighbor table (IPv6) or ARP table (IPv4) for
973 the given hardware address on the links matched for the network.
974 Specify several
<literal>[Neighbor]
</literal> sections to configure
975 several static neighbors.
</para>
977 <variablelist class='network-directives'
>
979 <term><varname>Address=
</varname></term>
981 <para>The IP address of the neighbor.
</para>
985 <term><varname>LinkLayerAddress=
</varname></term>
987 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
994 <title>[IPv6AddressLabel] Section Options
</title>
996 <para>An
<literal>[IPv6AddressLabel]
</literal> section accepts the
997 following keys. Specify several
<literal>[IPv6AddressLabel]
</literal>
998 sections to configure several address labels. IPv6 address labels are
999 used for address selection. See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>.
1000 Precedence is managed by userspace, and only the label itself is stored in the kernel
</para>
1002 <variablelist class='network-directives'
>
1004 <term><varname>Label=
</varname></term>
1006 <para> The label for the prefix (an unsigned integer) ranges
0 to
4294967294.
1007 0xffffffff is reserved. This key is mandatory.
</para>
1011 <term><varname>Prefix=
</varname></term>
1013 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
1014 This key is mandatory.
</para>
1021 <title>[RoutingPolicyRule] Section Options
</title>
1023 <para>An
<literal>[RoutingPolicyRule]
</literal> section accepts the
1024 following keys. Specify several
<literal>[RoutingPolicyRule]
</literal>
1025 sections to configure several rules.
</para>
1027 <variablelist class='network-directives'
>
1029 <term><varname>TypeOfService=
</varname></term>
1031 <para>Specifies the type of service to match a number between
0 to
255.
</para>
1035 <term><varname>From=
</varname></term>
1037 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1041 <term><varname>To=
</varname></term>
1043 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1047 <term><varname>FirewallMark=
</varname></term>
1049 <para>Specifies the iptables firewall mark value to match (a number between
1 and
4294967295).
</para>
1053 <term><varname>Table=
</varname></term>
1055 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes
1056 one of
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
1057 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1061 <term><varname>Priority=
</varname></term>
1063 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1064 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1068 <term><varname>IncomingInterface=
</varname></term>
1070 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1074 <term><varname>OutgoingInterface=
</varname></term>
1076 <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>
1080 <term><varname>SourcePort=
</varname></term>
1082 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1083 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1087 <term><varname>DestinationPort=
</varname></term>
1089 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1090 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1094 <term><varname>IPProtocol=
</varname></term>
1096 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1097 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1098 <literal>17</literal> for
<literal>udp
</literal>.
1099 Defaults to unset.
</para>
1103 <term><varname>InvertRule=
</varname></term>
1105 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1109 <term><varname>Family=
</varname></term>
1111 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1112 <literal>both
</literal>. By default, the address family is determined by the address
1113 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1114 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1115 <literal>ipv4
</literal>.
</para>
1119 <term><varname>User=
</varname></term>
1121 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1126 <term><varname>SuppressPrefixLength=
</varname></term>
1128 <para>Takes a number
<replaceable>N
</replaceable> in the range
0-
128 and rejects routing
1129 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1137 <title>[NextHop] Section Options
</title>
1138 <para>The
<literal>[NextHop]
</literal> section accepts the
1139 following keys. Specify several
<literal>[NextHop]
</literal>
1140 sections to configure several nexthop. Nexthop is used to manipulate entries in the kernel's nexthop
1143 <variablelist class='network-directives'
>
1145 <term><varname>Gateway=
</varname></term>
1147 <para>As in the
<literal>[Network]
</literal> section. This is mandatory.
</para>
1151 <term><varname>Id=
</varname></term>
1153 <para>The id of the nexthop (an unsigned integer). If unspecified or '
0' then automatically chosen by kernel.
</para>
1160 <title>[Route] Section Options
</title>
1161 <para>The
<literal>[Route]
</literal> section accepts the
1162 following keys. Specify several
<literal>[Route]
</literal>
1163 sections to configure several routes.
</para>
1165 <variablelist class='network-directives'
>
1167 <term><varname>Gateway=
</varname></term>
1169 <para>Takes the gateway address or special value
<literal>_dhcp
</literal>. If
1170 <literal>_dhcp
</literal>, then the gateway address provided by DHCP (or in the IPv6 case,
1171 provided by IPv6 RA) is used.
</para>
1175 <term><varname>GatewayOnLink=
</varname></term>
1177 <para>Takes a boolean. If set to true, the kernel does not have
1178 to check if the gateway is reachable directly by the current machine (i.e., the kernel does
1179 not need to check if the gateway is attached to the local network), so that we can insert the
1180 route in the kernel table without it being complained about. Defaults to
<literal>no
</literal>.
1185 <term><varname>Destination=
</varname></term>
1187 <para>The destination prefix of the route. Possibly
1188 followed by a slash and the prefix length. If omitted, a
1189 full-length host route is assumed.
</para>
1193 <term><varname>Source=
</varname></term>
1195 <para>The source prefix of the route. Possibly followed by
1196 a slash and the prefix length. If omitted, a full-length
1197 host route is assumed.
</para>
1201 <term><varname>Metric=
</varname></term>
1203 <para>The metric of the route (an unsigned integer).
</para>
1207 <term><varname>IPv6Preference=
</varname></term>
1209 <para>Specifies the route preference as defined in
<ulink
1210 url=
"https://tools.ietf.org/html/rfc4191">RFC4191
</ulink> for Router Discovery messages.
1211 Which can be one of
<literal>low
</literal> the route has a lowest priority,
1212 <literal>medium
</literal> the route has a default priority or
1213 <literal>high
</literal> the route has a highest priority.
</para>
1217 <term><varname>Scope=
</varname></term>
1219 <para>The scope of the route, which can be
<literal>global
</literal>,
<literal>site
</literal>,
1220 <literal>link
</literal>,
<literal>host
</literal>, or
<literal>nowhere
</literal>. For IPv4 route,
1221 defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
<literal>local
</literal>
1222 or
<literal>nat
</literal>, and
<literal>link
</literal> if
<varname>Type=
</varname> is
1223 <literal>broadcast
</literal>,
<literal>multicast
</literal>, or
<literal>anycast
</literal>.
1224 In other cases, defaults to
<literal>global
</literal>.
</para>
1228 <term><varname>PreferredSource=
</varname></term>
1230 <para>The preferred source address of the route. The address
1231 must be in the format described in
1232 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1236 <term><varname>Table=
</varname></term>
1238 <para>The table identifier for the route. Takes
<literal>default
</literal>,
1239 <literal>main
</literal>,
<literal>local
</literal> or a number between
1 and
4294967295.
1240 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1241 If unset and
<varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1242 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1243 In other cases, defaults to
<literal>main
</literal>.
1248 <term><varname>Protocol=
</varname></term>
1250 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1251 <literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1252 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1257 <term><varname>Type=
</varname></term>
1259 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1260 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1261 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1262 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1263 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1264 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1265 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1266 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1267 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1268 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1269 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1274 <term><varname>InitialCongestionWindow=
</varname></term>
1276 <para>The TCP initial congestion window is used during the start of a TCP connection. During the start of a TCP
1277 session, when a client requests a resource, the server's initial congestion window determines how many data bytes
1278 will be sent during the initial burst of data. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual
1279 suffixes K, M, G are supported and are understood to the base of
1024. When unset, the kernel's default will be used.
1284 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1286 <para>The TCP initial advertised receive window is the amount of receive data (in bytes) that can initially be buffered at one time
1287 on a connection. The sending host can send only that amount of data before waiting for an acknowledgment and window update
1288 from the receiving host. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual suffixes K, M, G are supported
1289 and are understood to the base of
1024. When unset, the kernel's default will be used.
1294 <term><varname>QuickAck=
</varname></term>
1296 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1301 <term><varname>FastOpenNoCookie=
</varname></term>
1303 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1304 When unset, the kernel's default will be used.
1309 <term><varname>TTLPropagate=
</varname></term>
1311 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1312 When unset, the kernel's default will be used.
1317 <term><varname>MTUBytes=
</varname></term>
1319 <para>The maximum transmission unit in bytes to set for the
1320 route. The usual suffixes K, M, G, are supported and are
1321 understood to the base of
1024.
</para>
1322 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1323 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1327 <term><varname>IPServiceType=
</varname></term>
1329 <para>Takes string;
<literal>CS6
</literal> or
<literal>CS4
</literal>. Used to set IP
1330 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.
</para>
1334 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1336 <para>Configures multipath route. Multipath routing is the technique of using multiple
1337 alternative paths through a network. Takes gateway address. Optionally, takes a network
1338 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for
1339 this multipath route separated with whitespace. This setting can be specified multiple
1340 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
1347 <title>[DHCPv4] Section Options
</title>
1348 <para>The
<literal>[DHCPv4]
</literal> section configures the
1349 DHCPv4 client, if it is enabled with the
1350 <varname>DHCP=
</varname> setting described above:
</para>
1352 <variablelist class='network-directives'
>
1354 <term><varname>UseDNS=
</varname></term>
1356 <para>When true (the default), the DNS servers received
1357 from the DHCP server will be used and take precedence over
1358 any statically configured ones.
</para>
1360 <para>This corresponds to the
<option>nameserver
</option>
1361 option in
<citerefentry
1362 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1366 <term><varname>RoutesToDNS=
</varname></term>
1368 <para>When true, the routes to the DNS servers received from the DHCP server will be
1369 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored.
1370 Defaults to false.
</para>
1374 <term><varname>UseNTP=
</varname></term>
1376 <para>When true (the default), the NTP servers received
1377 from the DHCP server will be used by systemd-timesyncd
1378 and take precedence over any statically configured ones.
</para>
1382 <term><varname>UseSIP=
</varname></term>
1384 <para>When true (the default), the SIP servers received
1385 from the DHCP server will be saved at the state files and can be
1386 read via
<function>sd_network_link_get_sip_servers()
</function> function.
</para>
1390 <term><varname>UseMTU=
</varname></term>
1392 <para>When true, the interface maximum transmission unit
1393 from the DHCP server will be used on the current link.
1394 If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
1395 Defaults to false.
</para>
1399 <term><varname>Anonymize=
</varname></term>
1401 <para>Takes a boolean. When true, the options sent to the DHCP server will
1402 follow the
<ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink>
1403 (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying information.
1404 Defaults to false.
</para>
1406 <para>This option should only be set to true when
1407 <varname>MACAddressPolicy=
</varname> is set to
<literal>random
</literal>
1409 project='man-pages'
><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
1411 <para>Note that this configuration will overwrite others.
1412 In concrete, the following variables will be ignored:
1413 <varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1414 <varname>UseRoutes=
</varname>,
<varname>UseMTU=
</varname>,
1415 <varname>VendorClassIdentifier=
</varname>,
<varname>UseTimezone=
</varname>.
</para>
1417 <para>With this option enabled DHCP requests will mimic those generated by Microsoft Windows, in
1418 order to reduce the ability to fingerprint and recognize installations. This means DHCP request
1419 sizes will grow and lease data will be more comprehensive than normally, though most of the
1420 requested data is not actually used.
</para>
1424 <term><varname>SendHostname=
</varname></term>
1426 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1427 Note that the machine's hostname must consist only of
7-bit ASCII lower-case characters and
1428 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1429 sent even if this is set to true.
</para>
1433 <term><varname>UseHostname=
</varname></term>
1435 <para>When true (the default), the hostname received from
1436 the DHCP server will be set as the transient hostname of the system.
1441 <term><varname>Hostname=
</varname></term>
1443 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1444 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1445 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1449 <term><varname>UseDomains=
</varname></term>
1451 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1452 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1453 the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name received from
1454 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1455 the
<option>Domains=
</option> setting when the argument is prefixed with
<literal>~
</literal>. Defaults to
1458 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1459 of all host names, in particular of single-label names. It is generally safer to use the supplied domain
1460 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1461 single-label names.
</para>
1463 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1464 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1468 <term><varname>UseRoutes=
</varname></term>
1470 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1471 routing table with a metric of
1024, and a scope of
"global",
"link" or
"host", depending on the route's
1472 destination and gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the
1473 link's own address, the scope will be set to
"host". Otherwise if the gateway is null (a direct route), a
1474 "link" scope will be used. For anything else, scope defaults to
"global".
</para>
1479 <term><varname>UseTimezone=
</varname></term>
1481 <listitem><para>When true, the timezone received from the
1482 DHCP server will be set as timezone of the local
1483 system. Defaults to
<literal>no
</literal>.
</para></listitem>
1487 <term><varname>ClientIdentifier=
</varname></term>
1489 <para>The DHCPv4 client identifier to use. Takes one of
<literal>mac
</literal>,
<literal>duid
</literal> or
<literal>duid-only
</literal>.
1490 If set to
<literal>mac
</literal>, the MAC address of the link is used.
1491 If set to
<literal>duid
</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1492 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.
1493 Defaults to
<literal>duid
</literal>.
</para>
1498 <term><varname>VendorClassIdentifier=
</varname></term>
1500 <para>The vendor class identifier used to identify vendor
1501 type and configuration.
</para>
1506 <term><varname>UserClass=
</varname></term>
1508 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1509 it represents. The information contained in this option is a string that represents the user class of which
1510 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1511 service to classify clients. Takes a whitespace-separated list of strings.
</para>
1516 <term><varname>MaxAttempts=
</varname></term>
1518 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1519 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>.
1520 Note that the time between retries is increased exponentially, so the network will not be
1521 overloaded even if this number is high.
</para>
1526 <term><varname>DUIDType=
</varname></term>
1528 <para>Override the global
<varname>DUIDType
</varname> setting for this network. See
1529 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1530 for a description of possible values.
</para>
1535 <term><varname>DUIDRawData=
</varname></term>
1537 <para>Override the global
<varname>DUIDRawData
</varname> setting for this network. See
1538 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1539 for a description of possible values.
</para>
1544 <term><varname>IAID=
</varname></term>
1546 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned integer.
</para>
1551 <term><varname>RequestBroadcast=
</varname></term>
1553 <para>Request the server to use broadcast messages before
1554 the IP address has been configured. This is necessary for
1555 devices that cannot receive RAW packets, or that cannot
1556 receive packets at all before an IP address has been
1557 configured. On the other hand, this must not be enabled on
1558 networks where broadcasts are filtered out.
</para>
1563 <term><varname>RouteMetric=
</varname></term>
1565 <para>Set the routing metric for routes specified by the
1571 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1573 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1574 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1576 <para>When used in combination with
<varname>VRF=
</varname> the
1577 VRF's routing table is used unless this parameter is specified.
1583 <term><varname>RouteMTUBytes=
</varname></term>
1585 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.
</para>
1590 <term><varname>ListenPort=
</varname></term>
1592 <para>Allow setting custom port for the DHCP client to listen on.
</para>
1597 <term><varname>SendRelease=
</varname></term>
1599 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops.
1600 Defaults to true.
</para>
1605 <term><varname>SendDecline=
</varname></term>
1607 <para>A boolen. When
<literal>true
</literal>, DHCPv4 clients receives IP address from DHCP server.
1608 After new IP is received, DHCPv4 performs IPv4 Duplicate Address Detection. If duplicate use of IP is detected
1609 the DHCPv4 client rejects the IP by sending a DHCPDECLINE packet DHCP clients try to obtain an IP address again.
1610 See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
1611 Defaults to
<literal>unset
</literal>.
</para>
1616 <term><varname>BlackList=
</varname></term>
1618 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are rejected.
</para>
1623 <term><varname>RequestOptions=
</varname></term>
1625 <para>A whitespace-separated list of integers in the range
1–
254.
</para>
1630 <term><varname>SendOption=
</varname></term>
1632 <para>Send an arbitrary option in the DHCPv4 request. Takes a DHCP option number, data type
1633 and data separated with a colon
1634 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1635 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1636 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1637 <literal>string
</literal>. Special characters in the data string may be escaped using
1638 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1639 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1640 then all options specified earlier are cleared. Defaults to unset.
</para>
1647 <title>[DHCPv6] Section Options
</title>
1648 <para>The
<literal>[DHCPv6]
</literal> section configures the DHCPv6 client, if it is enabled with the
1649 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
</para>
1651 <variablelist class='network-directives'
>
1653 <term><varname>UseDNS=
</varname></term>
1654 <term><varname>UseNTP=
</varname></term>
1656 <para>As in the
<literal>[DHCPv4]
</literal> section.
</para>
1661 <term><varname>RapidCommit=
</varname></term>
1663 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1664 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1665 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1666 four-method exchange (solicit, advertise, request, and reply). The two-message exchange provides
1667 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1668 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
1669 Defaults to true.
</para>
1674 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
1676 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
1677 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
1678 makes DHCPv6 request network information in a stateless manner using a two-message Information
1679 Request and Information Reply message exchange.
1680 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
1681 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
1682 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
1683 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
1684 By default this option is set to 'false', enable it if no prefixes are delegated when the device
1685 should be acting as a CE router.
</para>
1690 <term><varname>PrefixDelegationHint=
</varname></term>
1692 <para>Takes an IPv6 address with prefix length as
<varname>Address=
</varname> in
1693 the
"[Network]" section. Specifies the DHCPv6 client for the requesting router to include
1694 a prefix-hint in the DHCPv6 solicitation. Prefix ranges
1-
128. Defaults to unset.
</para>
1701 <title>[IPv6AcceptRA] Section Options
</title>
1702 <para>The
<literal>[IPv6AcceptRA]
</literal> section configures the IPv6 Router Advertisement
1703 (RA) client, if it is enabled with the
<varname>IPv6AcceptRA=
</varname> setting described
1706 <variablelist class='network-directives'
>
1708 <term><varname>UseDNS=
</varname></term>
1710 <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
1711 precedence over any statically configured ones.
</para>
1713 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
1714 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1719 <term><varname>UseDomains=
</varname></term>
1721 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1722 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
1723 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
1724 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
1725 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
1726 <literal>~
</literal>. Defaults to false.
</para>
1728 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1729 of all host names, in particular of single-label names. It is generally safer to use the supplied domain
1730 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1731 single-label names.
</para>
1733 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1734 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1739 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1741 <para>The table identifier for the routes received in the Router Advertisement
1742 (a number between
1 and
4294967295, or
0 to unset).
1743 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1749 <term><varname>UseAutonomousPrefix=
</varname></term>
1751 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
1752 precedence over any statically configured ones.
</para>
1757 <term><varname>UseOnLinkPrefix=
</varname></term>
1759 <para>When true (the default), the onlink prefix received in the Router Advertisement will be used and take
1760 precedence over any statically configured ones.
</para>
1765 <term><varname>BlackList=
</varname></term>
1767 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router advertisements in the list are ignored.
</para>
1775 <title>[DHCPServer] Section Options
</title>
1776 <para>The
<literal>[DHCPServer]
</literal> section contains
1777 settings for the DHCP server, if enabled via the
1778 <varname>DHCPServer=
</varname> option described above:
</para>
1780 <variablelist class='network-directives'
>
1783 <term><varname>PoolOffset=
</varname></term>
1784 <term><varname>PoolSize=
</varname></term>
1786 <listitem><para>Configures the pool of addresses to hand out. The pool
1787 is a contiguous sequence of IP addresses in the subnet configured for
1788 the server address, which does not include the subnet nor the broadcast
1789 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
1790 from the start of subnet, or zero to use the default value.
1791 <varname>PoolSize=
</varname> takes the number of IP addresses in the
1792 pool or zero to use the default value. By default, the pool starts at
1793 the first address after the subnet address and takes up the rest of
1794 the subnet, excluding the broadcast address. If the pool includes
1795 the server address (the default), this is reserved and not handed
1796 out to clients.
</para></listitem>
1800 <term><varname>DefaultLeaseTimeSec=
</varname></term>
1801 <term><varname>MaxLeaseTimeSec=
</varname></term>
1803 <listitem><para>Control the default and maximum DHCP lease
1804 time to pass to clients. These settings take time values in seconds or
1805 another common time unit, depending on the suffix. The default
1806 lease time is used for clients that did not ask for a specific
1807 lease time. If a client asks for a lease time longer than the
1808 maximum lease time, it is automatically shortened to the
1809 specified time. The default lease time defaults to
1h, the
1810 maximum lease time to
12h. Shorter lease times are beneficial
1811 if the configuration data in DHCP leases changes frequently
1812 and clients shall learn the new settings with shorter
1813 latencies. Longer lease times reduce the generated DHCP
1814 network traffic.
</para></listitem>
1818 <term><varname>EmitDNS=
</varname></term>
1819 <term><varname>DNS=
</varname></term>
1821 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1822 to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
1823 The DNS servers to pass to clients may be configured with the
1824 <varname>DNS=
</varname> option, which takes a list of IPv4
1825 addresses. If the
<varname>EmitDNS=
</varname> option is
1826 enabled but no servers configured, the servers are
1827 automatically propagated from an
"uplink" interface that has
1828 appropriate servers set. The
"uplink" interface is determined
1829 by the default route of the system with the highest
1830 priority. Note that this information is acquired at the time
1831 the lease is handed out, and does not take uplink interfaces
1832 into account that acquire DNS or NTP server information at a
1833 later point. DNS server propagation does not take
1834 <filename>/etc/resolv.conf
</filename> into account. Also, note
1835 that the leases are not refreshed if the uplink network
1836 configuration changes. To ensure clients regularly acquire the
1837 most current uplink DNS server information, it is thus
1838 advisable to shorten the DHCP lease time via
1839 <varname>MaxLeaseTimeSec=
</varname> described
1840 above.
</para></listitem>
1844 <term><varname>EmitNTP=
</varname></term>
1845 <term><varname>NTP=
</varname></term>
1847 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1848 <varname>DNS=
</varname> settings described above, these
1849 settings configure whether and what NTP server information
1850 shall be emitted as part of the DHCP lease. The same syntax,
1851 propagation semantics and defaults apply as for
1852 <varname>EmitDNS=
</varname> and
1853 <varname>DNS=
</varname>.
</para></listitem>
1857 <term><varname>EmitSIP=
</varname></term>
1858 <term><varname>SIP=
</varname></term>
1860 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1861 <varname>DNS=
</varname> settings described above, these
1862 settings configure whether and what SIP server information
1863 shall be emitted as part of the DHCP lease. The same syntax,
1864 propagation semantics and defaults apply as for
1865 <varname>EmitDNS=
</varname> and
1866 <varname>DNS=
</varname>.
</para></listitem>
1870 <term><varname>EmitRouter=
</varname></term>
1872 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
1873 setting described above, this setting configures whether the
1874 DHCP lease should contain the router option. The same syntax,
1875 propagation semantics and defaults apply as for
1876 <varname>EmitDNS=
</varname>.
</para></listitem>
1880 <term><varname>EmitTimezone=
</varname></term>
1881 <term><varname>Timezone=
</varname></term>
1883 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1884 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
1885 <varname>Timezone=
</varname> setting takes a timezone string
1886 (such as
<literal>Europe/Berlin
</literal> or
1887 <literal>UTC
</literal>) to pass to clients. If no explicit
1888 timezone is set, the system timezone of the local host is
1889 propagated, as determined by the
1890 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
1894 <term><varname>SendOption=
</varname></term>
1896 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
1897 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1898 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1899 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1900 <literal>string
</literal>. Special characters in the data string may be escaped using
1901 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1902 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1903 then all options specified earlier are cleared. Defaults to unset.
</para>
1911 <title>[IPv6PrefixDelegation] Section Options
</title>
1912 <para>The
<literal>[IPv6PrefixDelegation]
</literal> section contains
1913 settings for sending IPv6 Router Advertisements and whether to act as
1914 a router, if enabled via the
<varname>IPv6PrefixDelegation=
</varname>
1915 option described above. IPv6 network prefixes are defined with one or
1916 more
<literal>[IPv6Prefix]
</literal> sections.
</para>
1918 <variablelist class='network-directives'
>
1921 <term><varname>Managed=
</varname></term>
1922 <term><varname>OtherInformation=
</varname></term>
1924 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
1925 addresses on the network link when
<varname>Managed=
</varname>
1926 is set to
<literal>true
</literal> or if only additional network
1927 information can be obtained via DHCPv6 for the network link when
1928 <varname>OtherInformation=
</varname> is set to
1929 <literal>true
</literal>. Both settings default to
1930 <literal>false
</literal>, which means that a DHCPv6 server is not being
1931 used.
</para></listitem>
1935 <term><varname>RouterLifetimeSec=
</varname></term>
1937 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. If set,
1938 this host also announces itself in Router Advertisements as an IPv6
1939 router for the network link. When unset, the host is not acting as a router.
</para>
1944 <term><varname>RouterPreference=
</varname></term>
1946 <listitem><para>Configures IPv6 router preference if
1947 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
1948 <literal>high
</literal>,
<literal>medium
</literal> and
1949 <literal>low
</literal>, with
<literal>normal
</literal> and
1950 <literal>default
</literal> added as synonyms for
1951 <literal>medium
</literal> just to make configuration easier. See
1952 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
1953 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
1957 <term><varname>EmitDNS=
</varname></term>
1958 <term><varname>DNS=
</varname></term>
1960 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
1961 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is
1962 true.
<varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that
1963 case the IPv6 link local address is distributed. If
<varname>DNS=
</varname> is empty, DNS
1964 servers are read from the
<literal>[Network]
</literal> section. If the
1965 <literal>[Network]
</literal> section does not contain any DNS servers either, DNS servers from
1966 the uplink with the highest priority default route are used. When
<varname>EmitDNS=
</varname>
1967 is false, no DNS server information is sent in Router Advertisement messages.
1968 <varname>EmitDNS=
</varname> defaults to true.
1973 <term><varname>EmitDomains=
</varname></term>
1974 <term><varname>Domains=
</varname></term>
1976 <listitem><para>A list of DNS search domains distributed via Router
1977 Advertisement messages when
<varname>EmitDomains=
</varname> is true. If
1978 <varname>Domains=
</varname> is empty, DNS search domains are read from the
1979 <literal>[Network]
</literal> section. If the
<literal>[Network]
</literal>
1980 section does not contain any DNS search domains either, DNS search
1981 domains from the uplink with the highest priority default route are
1982 used. When
<varname>EmitDomains=
</varname> is false, no DNS search domain
1983 information is sent in Router Advertisement messages.
1984 <varname>EmitDomains=
</varname> defaults to true.
1989 <term><varname>DNSLifetimeSec=
</varname></term>
1991 <listitem><para>Lifetime in seconds for the DNS server addresses listed
1992 in
<varname>DNS=
</varname> and search domains listed in
1993 <varname>Domains=
</varname>.
</para></listitem>
2000 <title>[IPv6Prefix] Section Options
</title>
2001 <para>One or more
<literal>[IPv6Prefix]
</literal> sections contain the IPv6
2002 prefixes that are announced via Router Advertisements. See
2003 <ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink>
2004 for further details.
</para>
2006 <variablelist class='network-directives'
>
2009 <term><varname>AddressAutoconfiguration=
</varname></term>
2010 <term><varname>OnLink=
</varname></term>
2012 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
2013 autoconfigured with this prefix and whether the prefix can be used for
2014 onlink determination. Both settings default to
<literal>true
</literal>
2015 in order to ease configuration.
2020 <term><varname>Prefix=
</varname></term>
2022 <listitem><para>The IPv6 prefix that is to be distributed to hosts.
2023 Similarly to configuring static IPv6 addresses, the setting is
2024 configured as an IPv6 prefix and its prefix length, separated by a
2025 <literal>/
</literal> character. Use multiple
2026 <literal>[IPv6Prefix]
</literal> sections to configure multiple IPv6
2027 prefixes since prefix lifetimes, address autoconfiguration and onlink
2028 status may differ from one prefix to another.
</para></listitem>
2032 <term><varname>PreferredLifetimeSec=
</varname></term>
2033 <term><varname>ValidLifetimeSec=
</varname></term>
2035 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2036 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
2037 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
2038 to
2592000 seconds (
30 days).
</para></listitem>
2042 <term><varname>Assign=
</varname></term>
2043 <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
2050 <title>[IPv6RoutePrefix] Section Options
</title>
2051 <para>One or more
<literal>[IPv6RoutePrefix]
</literal> sections contain the IPv6
2052 prefix routes that are announced via Router Advertisements. See
2053 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2054 for further details.
</para>
2056 <variablelist class='network-directives'
>
2059 <term><varname>Route=
</varname></term>
2061 <listitem><para>The IPv6 route that is to be distributed to hosts.
2062 Similarly to configuring static IPv6 routes, the setting is
2063 configured as an IPv6 prefix routes and its prefix route length,
2064 separated by a
<literal>/
</literal> character. Use multiple
2065 <literal>[IPv6PrefixRoutes]
</literal> sections to configure multiple IPv6
2066 prefix routes.
</para></listitem>
2070 <term><varname>LifetimeSec=
</varname></term>
2072 <listitem><para>Lifetime for the route prefix measured in
2073 seconds.
<varname>LifetimeSec=
</varname> defaults to
604800 seconds (one week).
2081 <title>[Bridge] Section Options
</title>
2082 <para>The
<literal>[Bridge]
</literal> section accepts the
2083 following keys.
</para>
2084 <variablelist class='network-directives'
>
2086 <term><varname>UnicastFlood=
</varname></term>
2088 <para>Takes a boolean. Controls whether the bridge should flood
2089 traffic for which an FDB entry is missing and the destination
2090 is unknown through this port. When unset, the kernel's default will be used.
2095 <term><varname>MulticastFlood=
</varname></term>
2097 <para>Takes a boolean. Controls whether the bridge should flood
2098 traffic for which an MDB entry is missing and the destination
2099 is unknown through this port. When unset, the kernel's default will be used.
2104 <term><varname>MulticastToUnicast=
</varname></term>
2106 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2107 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2108 When unset, the kernel's default will be used.
2113 <term><varname>NeighborSuppression=
</varname></term>
2115 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2116 this port. When unset, the kernel's default will be used.
2121 <term><varname>Learning=
</varname></term>
2123 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2124 this port. When unset, the kernel's default will be used.
2129 <term><varname>HairPin=
</varname></term>
2131 <para>Takes a boolean. Configures whether traffic may be sent back
2132 out of the port on which it was received. When this flag is false, and the bridge
2133 will not forward traffic back out of the receiving port.
2134 When unset, the kernel's default will be used.
</para>
2138 <term><varname>UseBPDU=
</varname></term>
2140 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2141 processed by the bridge port. When unset, the kernel's default will be used.
</para>
2145 <term><varname>FastLeave=
</varname></term>
2147 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2148 traffic on a port that receives an IGMP Leave message. It is only used with
2149 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
2153 <term><varname>AllowPortToBeRoot=
</varname></term>
2155 <para>Takes a boolean. Configures whether a given port is allowed to
2156 become a root port. Only used when STP is enabled on the bridge.
2157 When unset, the kernel's default will be used.
</para>
2161 <term><varname>ProxyARP=
</varname></term>
2163 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2164 When unset, the kernel's default will be used.
</para>
2168 <term><varname>ProxyARPWiFi=
</varname></term>
2170 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2171 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
2172 When unset, the kernel's default will be used.
</para>
2176 <term><varname>MulticastRouter=
</varname></term>
2178 <para>Configures this port for having multicast routers attached. A port with a multicast
2179 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
2180 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
2181 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
2182 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
2183 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
2187 <term><varname>Cost=
</varname></term>
2189 <para>Sets the
"cost" of sending packets of this interface.
2190 Each port in a bridge may have a different speed and the cost
2191 is used to decide which link to use. Faster interfaces
2192 should have lower costs. It is an integer value between
1 and
2197 <term><varname>Priority=
</varname></term>
2199 <para>Sets the
"priority" of sending packets on this interface.
2200 Each port in a bridge may have a different priority which is used
2201 to decide which link to use. Lower value means higher priority.
2202 It is an integer value between
0 to
63. Networkd does not set any
2203 default, meaning the kernel default value of
32 is used.
</para>
2209 <title>[BridgeFDB] Section Options
</title>
2210 <para>The
<literal>[BridgeFDB]
</literal> section manages the
2211 forwarding database table of a port and accepts the following
2212 keys. Specify several
<literal>[BridgeFDB]
</literal> sections to
2213 configure several static MAC table entries.
</para>
2215 <variablelist class='network-directives'
>
2217 <term><varname>MACAddress=
</varname></term>
2219 <para>As in the
<literal>[Network]
</literal> section. This
2220 key is mandatory.
</para>
2224 <term><varname>Destination=
</varname></term>
2226 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
2230 <term><varname>VLANId=
</varname></term>
2232 <para>The VLAN ID for the new static MAC table entry. If
2233 omitted, no VLAN ID information is appended to the new static MAC
2238 <term><varname>VNI=
</varname></term>
2240 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2241 the remote VXLAN tunnel endpoint. Takes a number in the range
1-
16777215.
2242 Defaults to unset.
</para>
2246 <term><varname>AssociatedWith=
</varname></term>
2248 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
2249 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
2250 <literal>use
</literal> means the address is in use. User space can use this option to
2251 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
2252 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
2253 means the address is associated with master devices fdb.
<literal>router
</literal> means
2254 the destination address is associated with a router. Note that it's valid if the referenced
2255 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
2262 <title>[CAN] Section Options
</title>
2263 <para>The
<literal>[CAN]
</literal> section manages the Controller Area Network (CAN bus) and accepts the
2264 following keys.
</para>
2265 <variablelist class='network-directives'
>
2267 <term><varname>BitRate=
</varname></term>
2269 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
2270 be used here.
</para>
2274 <term><varname>SamplePoint=
</varname></term>
2276 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2277 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2281 <term><varname>RestartSec=
</varname></term>
2283 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2284 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2285 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2286 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2287 automatic restart off. By default automatic restart is disabled.
</para>
2291 <term><varname>TripleSampling=
</varname></term>
2293 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2294 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
2301 <title>[QDisc] Section Options
</title>
2302 <para>The
<literal>[QDisc]
</literal> section manages the traffic control queueing discipline (qdisc).
</para>
2304 <variablelist class='network-directives'
>
2306 <term><varname>Parent=
</varname></term>
2308 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
2309 or
<literal>ingress
</literal>. This is mandatory.
</para>
2314 <term><varname>Handle=
</varname></term>
2316 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2317 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2324 <title>[NetworkEmulator] Section Options
</title>
2325 <para>The
<literal>[NetworkEmulator]
</literal> section manages the queueing discipline (qdisc) of
2326 the network emulator. It can be used to configure the kernel packet scheduler and simulate packet
2327 delay and loss for UDP or TCP applications, or limit the bandwidth usage of a particular service to
2328 simulate internet connections.
</para>
2330 <variablelist class='network-directives'
>
2332 <term><varname>Parent=
</varname></term>
2334 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2335 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2340 <term><varname>Handle=
</varname></term>
2342 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2343 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2348 <term><varname>DelaySec=
</varname></term>
2350 <para>Specifies the fixed amount of delay to be added to all packets going out of the
2351 interface. Defaults to unset.
</para>
2356 <term><varname>DelayJitterSec=
</varname></term>
2358 <para>Specifies the chosen delay to be added to the packets outgoing to the network
2359 interface. Defaults to unset.
</para>
2364 <term><varname>PacketLimit=
</varname></term>
2366 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
2367 An unsigned integer ranges
0 to
4294967294. Defaults to
1000.
</para>
2372 <term><varname>LossRate=
</varname></term>
2374 <para>Specifies an independent loss probability to be added to the packets outgoing from the
2375 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2380 <term><varname>DuplicateRate=
</varname></term>
2382 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
2383 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2390 <title>[TokenBucketFilter] Section Options
</title>
2391 <para>The
<literal>[TokenBucketFilter]
</literal> section manages the queueing discipline (qdisc) of
2392 token bucket filter (tbf).
</para>
2394 <variablelist class='network-directives'
>
2396 <term><varname>Parent=
</varname></term>
2398 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2399 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2404 <term><varname>Handle=
</varname></term>
2406 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2407 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2412 <term><varname>LatencySec=
</varname></term>
2414 <para>Specifies the latency parameter, which specifies the maximum amount of time a
2415 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
2420 <term><varname>LimitSize=
</varname></term>
2422 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
2423 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
2424 respectively, to the base of
1000. Defaults to unset.
</para>
2429 <term><varname>Burst=
</varname></term>
2431 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
2432 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
2433 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to
2439 <term><varname>Rate=
</varname></term>
2441 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
2442 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
2443 Defaults to unset.
</para>
2448 <term><varname>MPUBytes=
</varname></term>
2450 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
2451 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2452 Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to zero.
</para>
2457 <term><varname>PeakRate=
</varname></term>
2459 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
2460 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2461 1000. Defaults to unset.
</para>
2466 <term><varname>MTUBytes=
</varname></term>
2468 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
2469 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000.
2470 Defaults to unset.
</para>
2477 <title>[StochasticFairnessQueueing] Section Options
</title>
2478 <para>The
<literal>[StochasticFairnessQueueing]
</literal> section manages the queueing discipline
2479 (qdisc) of stochastic fairness queueing (sfq).
</para>
2481 <variablelist class='network-directives'
>
2483 <term><varname>Parent=
</varname></term>
2485 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2486 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2491 <term><varname>Handle=
</varname></term>
2493 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2494 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2499 <term><varname>PerturbPeriodSec=
</varname></term>
2501 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
2508 <title>[ControlledDelay] Section Options
</title>
2509 <para>The
<literal>[ControlledDelay]
</literal> section manages the queueing discipline (qdisc) of
2510 controlled delay (CoDel).
</para>
2512 <variablelist class='network-directives'
>
2514 <term><varname>Parent=
</varname></term>
2516 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2517 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2522 <term><varname>Handle=
</varname></term>
2524 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2525 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2530 <term><varname>PacketLimit=
</varname></term>
2532 <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
2533 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2538 <term><varname>TargetSec=
</varname></term>
2540 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2541 Defaults to unset and kernel's default is used.
</para>
2546 <term><varname>IntervalSec=
</varname></term>
2548 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2549 become too stale. Defaults to unset and kernel's default is used.
</para>
2554 <term><varname>ECN=
</varname></term>
2556 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2557 unset and kernel's default is used.
</para>
2562 <term><varname>CEThresholdSec=
</varname></term>
2564 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2565 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2572 <title>[FairQueueingControlledDelay] Section Options
</title>
2573 <para>The
<literal>[FairQueueingControlledDelay]
</literal> section manages the queueing discipline
2574 (qdisc) of fair queuing controlled delay (FQ-CoDel).
</para>
2576 <variablelist class='network-directives'
>
2578 <term><varname>Parent=
</varname></term>
2580 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2581 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2586 <term><varname>Handle=
</varname></term>
2588 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2589 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2594 <term><varname>PacketLimit=
</varname></term>
2596 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2597 dropped. Defaults to unset and kernel's default is used.
</para>
2602 <term><varname>MemoryLimit=
</varname></term>
2604 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
2605 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2606 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2611 <term><varname>Flows=
</varname></term>
2613 <para>Specifies the number of flows into which the incoming packets are classified.
2614 Defaults to unset and kernel's default is used.
</para>
2619 <term><varname>TargetSec=
</varname></term>
2621 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2622 Defaults to unset and kernel's default is used.
</para>
2627 <term><varname>IntervalSec=
</varname></term>
2629 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2630 become too stale. Defaults to unset and kernel's default is used.
</para>
2635 <term><varname>Quantum=
</varname></term>
2637 <para>Specifies the number of bytes used as 'deficit' in the fair queuing algorithmtimespan.
2638 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2639 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2644 <term><varname>ECN=
</varname></term>
2646 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2647 unset and kernel's default is used.
</para>
2652 <term><varname>CEThresholdSec=
</varname></term>
2654 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2655 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2662 <title>[FairQueueing] Section Options
</title>
2663 <para>The
<literal>[FairQueueing]
</literal> section manages the queueing discipline
2664 (qdisc) of fair queue traffic policing (FQ).
</para>
2666 <variablelist class='network-directives'
>
2668 <term><varname>Parent=
</varname></term>
2670 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2671 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2676 <term><varname>Handle=
</varname></term>
2678 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2679 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2684 <term><varname>PacketLimit=
</varname></term>
2686 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2687 dropped. Defaults to unset and kernel's default is used.
</para>
2692 <term><varname>FlowLimit=
</varname></term>
2694 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
2695 unset and kernel's default is used.
</para>
2700 <term><varname>Quantum=
</varname></term>
2702 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
2703 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2704 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
2705 default is used.
</para>
2710 <term><varname>InitialQuantum=
</varname></term>
2712 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
2713 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
2714 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
2715 kernel's default is used.
</para>
2720 <term><varname>MaximumRate=
</varname></term>
2722 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
2723 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2724 1000. Defaults to unset and kernel's default is used.
</para>
2729 <term><varname>Buckets=
</varname></term>
2731 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
2732 kernel's default is used.
</para>
2737 <term><varname>OrphanMask=
</varname></term>
2739 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
2740 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
2741 kernel's default is used.
</para>
2746 <term><varname>Pacing=
</varname></term>
2748 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
2749 default is used.
</para>
2754 <term><varname>CEThresholdSec=
</varname></term>
2756 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2757 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2764 <title>[TrivialLinkEqualizer] Section Options
</title>
2765 <para>The
<literal>[TrivialLinkEqualizer]
</literal> section manages the queueing discipline (qdisc) of
2766 trivial link equalizer (teql).
</para>
2768 <variablelist class='network-directives'
>
2770 <term><varname>Parent=
</varname></term>
2772 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2773 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2778 <term><varname>Handle=
</varname></term>
2780 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2781 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2786 <term><varname>Id=
</varname></term>
2788 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
2789 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
2790 <constant>max_equalizers=N+
1</constant> option must be loaded before
2791 <command>systemd-networkd
</command> is started.
</para>
2798 <title>[BridgeVLAN] Section Options
</title>
2799 <para>The
<literal>[BridgeVLAN]
</literal> section manages the VLAN ID configuration of a bridge port and accepts
2800 the following keys. Specify several
<literal>[BridgeVLAN]
</literal> sections to configure several VLAN entries.
2801 The
<varname>VLANFiltering=
</varname> option has to be enabled, see
<literal>[Bridge]
</literal> section in
2802 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2804 <variablelist class='network-directives'
>
2806 <term><varname>VLAN=
</varname></term>
2808 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
2809 from
1 to
4094.
</para>
2813 <term><varname>EgressUntagged=
</varname></term>
2815 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
2816 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
2817 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
2821 <term><varname>PVID=
</varname></term>
2823 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
2824 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
2825 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
2832 <title>Examples
</title>
2834 <title>Static network configuration
</title>
2836 <programlisting># /etc/systemd/network/
50-static.network
2841 Address=
192.168.0.15/
24
2842 Gateway=
192.168.0.1</programlisting>
2844 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
2845 specified gateway will be used for a default route.
</para>
2849 <title>DHCP on ethernet links
</title>
2851 <programlisting># /etc/systemd/network/
80-dhcp.network
2856 DHCP=yes
</programlisting>
2858 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
2859 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
2863 <title>IPv6 Prefix Delegation
</title>
2865 <programlisting># /etc/systemd/network/
55-ipv6-pd-upstream.network
2870 DHCP=ipv6
</programlisting>
2872 <programlisting># /etc/systemd/network/
56-ipv6-pd-downstream.network
2877 IPv6PrefixDelegation=dhcpv6
</programlisting>
2879 <para>This will enable IPv6 PD on the interface enp1s0 as an upstream interface where the
2880 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
</para>
2884 <title>A bridge with two enslaved links
</title>
2886 <programlisting># /etc/systemd/network/
25-bridge-static.network
2891 Address=
192.168.0.15/
24
2893 DNS=
192.168.0.1</programlisting>
2895 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
2900 Bridge=bridge0
</programlisting>
2902 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
2907 Bridge=bridge0
</programlisting>
2909 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
2910 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
2911 and network assigned, and a default route via the specified gateway will be
2912 added. The specified DNS server will be added to the global list of DNS resolvers.
2920 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
2936 EgressUntagged=
300-
400</programlisting>
2938 <para>This overrides the configuration specified in the previous example for the
2939 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
2940 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
2941 untagged when they leave on this interface. Untagged packets which arrive on this
2942 interface will be assigned VLAN ID
42.
</para>
2946 <title>Various tunnels
</title>
2948 <programlisting>/etc/systemd/network/
25-tunnels.network
2959 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
2965 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
2971 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
2977 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
2983 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
2984 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
2988 <title>A bond device
</title>
2990 <programlisting># /etc/systemd/network/
30-bond1.network
2998 <programlisting># /etc/systemd/network/
30-bond1.netdev
3004 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
3006 MACAddress=
52:
54:
00:e9:
64:
41
3012 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
3014 MACAddress=
52:
54:
00:e9:
64:
42
3020 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
3021 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
3022 will be used to acquire an address.
</para>
3026 <title>Virtual Routing and Forwarding (VRF)
</title>
3027 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
3028 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
3029 within the routing table defined during VRF creation. For kernels before
4.8 traffic
3030 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
3032 <programlisting># /etc/systemd/network/
25-vrf.network
3042 <title>MacVTap
</title>
3043 <para>This brings up a network interface
<literal>macvtap-test
</literal>
3044 and attaches it to
<literal>enp0s25
</literal>.
</para>
3045 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
3050 MACVTAP=macvtap-test
3055 <title>A Xfrm interface with physical underlying device.
</title>
3057 <programlisting># /etc/systemd/network/
27-xfrm.netdev
3062 InterfaceId=
7</programlisting>
3064 <programlisting># /etc/systemd/network/
27-eth0.network
3069 Xfrm=xfrm0
</programlisting>
3071 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
3072 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
3073 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
3079 <title>See Also
</title>
3081 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
3082 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
3083 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3084 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3085 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
projects / thirdparty / systemd.git / blob