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>Network setup is performed by
32 <citerefentry><refentrytitle>systemd-networkd
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
35 <para>The main network file must have the extension
<filename>.network
</filename>; other
36 extensions are ignored. Networks are applied to links whenever the links appear.
</para>
38 <para>The
<filename>.network
</filename> files are read from the files located in the system network
39 directories
<filename>/usr/lib/systemd/network
</filename> and
40 <filename>/usr/local/lib/systemd/network
</filename>, the volatile runtime network directory
41 <filename>/run/systemd/network
</filename> and the local administration network directory
42 <filename>/etc/systemd/network
</filename>. All configuration files are collectively sorted and processed
43 in lexical order, regardless of the directories in which they live. However, files with identical
44 filenames replace each other. Files in
<filename>/etc
</filename> have the highest priority, files in
45 <filename>/run
</filename> take precedence over files with the same name under
46 <filename>/usr
</filename>. This can be used to override a system-supplied configuration file with a local
47 file if needed. As a special case, an empty file (file size
0) or symlink with the same name pointing to
48 <filename>/dev/null
</filename> disables the configuration file entirely (it is
"masked").
</para>
50 <para>Along with the network file
<filename>foo.network
</filename>, a
"drop-in" directory
51 <filename>foo.network.d/
</filename> may exist. All files with the suffix
52 <literal>.conf
</literal> from this directory will be parsed after the file itself is
53 parsed. This is useful to alter or add configuration settings, without having to modify the main
54 configuration file. Each drop-in file must have appropriate section headers.
</para>
56 <para>In addition to
<filename>/etc/systemd/network
</filename>, drop-in
<literal>.d
</literal>
57 directories can be placed in
<filename>/usr/lib/systemd/network
</filename> or
58 <filename>/run/systemd/network
</filename> directories. Drop-in files in
59 <filename>/etc
</filename> take precedence over those in
<filename>/run
</filename> which in turn
60 take precedence over those in
<filename>/usr/lib
</filename>. Drop-in files under any of these
61 directories take precedence over the main network file wherever located.
</para>
63 <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6
64 nor IPv6LL enabled, shall be considered to have no IPv6 support. IPv6 will be automatically
65 disabled for that interface by writing
"1" to
66 <filename>/proc/sys/net/ipv6/conf/
<replaceable>ifname
</replaceable>/disable_ipv6
</filename>.
71 <title>[Match] Section Options
</title>
73 <para>The network file contains a
<literal>[Match]
</literal>
74 section, which determines if a given network file may be applied
75 to a given device; and a
<literal>[Network]
</literal> section
76 specifying how the device should be configured. The first (in
77 lexical order) of the network files that matches a given device
78 is applied, all later files are ignored, even if they match as
81 <para>A network file is said to match a network interface if all matches specified by the
82 <literal>[Match]
</literal> section are satisfied. When a network file does not contain valid
83 settings in
<literal>[Match]
</literal> section, then the file will match all interfaces and
84 <command>systemd-networkd
</command> warns about that. Hint: to avoid the warning and to make it
85 clear that all interfaces shall be matched, add the following:
86 <programlisting>Name=*
</programlisting>
87 The following keys are accepted:
</para>
89 <variablelist class='network-directives'
>
90 <xi:include href=
"systemd.link.xml" xpointer=
"mac-address" />
91 <xi:include href=
"systemd.link.xml" xpointer=
"permanent-mac-address" />
92 <xi:include href=
"systemd.link.xml" xpointer=
"path" />
93 <xi:include href=
"systemd.link.xml" xpointer=
"driver" />
94 <xi:include href=
"systemd.link.xml" xpointer=
"type" />
95 <xi:include href=
"systemd.link.xml" xpointer=
"property" />
98 <term><varname>Name=
</varname></term>
100 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
101 by the udev property
<literal>INTERFACE
</literal>, or device's alternative names. If the
102 list is prefixed with a
"!", the test is inverted.
</para>
107 <term><varname>WLANInterfaceType=
</varname></term>
109 <para>A whitespace-separated list of wireless network type. Supported values are
110 <literal>ad-hoc
</literal>,
<literal>station
</literal>,
<literal>ap
</literal>,
111 <literal>ap-vlan
</literal>,
<literal>wds
</literal>,
<literal>monitor
</literal>,
112 <literal>mesh-point
</literal>,
<literal>p2p-client
</literal>,
<literal>p2p-go
</literal>,
113 <literal>p2p-device
</literal>,
<literal>ocb
</literal>, and
<literal>nan
</literal>. If the
114 list is prefixed with a
"!", the test is inverted.
120 <term><varname>SSID=
</varname></term>
122 <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
123 connected wireless LAN. If the list is prefixed with a
"!", the test is inverted.
129 <term><varname>BSSID=
</varname></term>
131 <para>A whitespace-separated list of hardware address of the currently connected wireless
132 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
133 <varname>MACAddress=
</varname>. This option may appear more than one, in which case the
134 lists are merged. If the empty string is assigned to this option, the list of BSSID defined
135 prior to this is reset.
</para>
139 <xi:include href=
"systemd.link.xml" xpointer=
"host" />
140 <xi:include href=
"systemd.link.xml" xpointer=
"virtualization" />
141 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-command-line" />
142 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-version" />
143 <xi:include href=
"systemd.link.xml" xpointer=
"architecture" />
149 <title>[Link] Section Options
</title>
151 <para> The
<literal>[Link]
</literal> section accepts the following keys:
</para>
153 <variablelist class='network-directives'
>
155 <term><varname>MACAddress=
</varname></term>
157 <para>The hardware address to set for the device.
</para>
161 <term><varname>MTUBytes=
</varname></term>
163 <para>The maximum transmission unit in bytes to set for the
164 device. The usual suffixes K, M, G, are supported and are
165 understood to the base of
1024.
</para>
166 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
167 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
171 <term><varname>ARP=
</varname></term>
173 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
174 for this interface is enabled. When unset, the kernel's default will be used.
</para>
175 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
176 interfaces atop a single lower-level physical interface, which will then only serve as a
177 link/
"bridge" device aggregating traffic to the same physical link and not participate in
178 the network otherwise.
</para>
182 <term><varname>Multicast=
</varname></term>
184 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled.
</para>
188 <term><varname>AllMulticast=
</varname></term>
190 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the network.
191 This happens when multicast routing is enabled.
</para>
195 <term><varname>Unmanaged=
</varname></term>
197 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are
198 made to bring up or configure matching links, equivalent to
199 when there are no matching network files. Defaults to
200 <literal>no
</literal>.
</para>
201 <para>This is useful for preventing later matching network
202 files from interfering with certain interfaces that are fully
203 controlled by other applications.
</para>
207 <term><varname>RequiredForOnline=
</varname></term>
209 <para>Takes a boolean or operational state. Please see
210 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
211 for possible operational states. When
<literal>yes
</literal>, the network is deemed required when
212 determining whether the system is online when running
213 <command>systemd-networkd-wait-online
</command>. When
<literal>no
</literal>, the network is ignored
214 when checking for online state. When an operational state is set,
<literal>yes
</literal> is implied,
215 and this controls the operational state required for the network interface to be considered online.
216 Defaults to
<literal>yes
</literal>.
</para>
218 <para>The network will be brought up normally in all cases, but in
219 the event that there is no address being assigned by DHCP or the
220 cable is not plugged in, the link will simply remain offline and be
221 skipped automatically by
<command>systemd-networkd-wait-online
</command>
222 if
<literal>RequiredForOnline=no
</literal>.
</para>
229 <title>[Network] Section Options
</title>
231 <para>The
<literal>[Network]
</literal> section accepts the following keys:
</para>
233 <variablelist class='network-directives'
>
235 <term><varname>Description=
</varname></term>
237 <para>A description of the device. This is only used for
238 presentation purposes.
</para>
242 <term><varname>DHCP=
</varname></term>
244 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
245 <literal>yes
</literal>,
<literal>no
</literal>,
246 <literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults
247 to
<literal>no
</literal>.
</para>
249 <para>Note that DHCPv6 will by default be triggered by Router
250 Advertisement, if that is enabled, regardless of this parameter.
251 By enabling DHCPv6 support explicitly, the DHCPv6 client will
252 be started regardless of the presence of routers on the link,
253 or what flags the routers pass. See
254 <literal>IPv6AcceptRA=
</literal>.
</para>
256 <para>Furthermore, note that by default the domain name
257 specified through DHCP is not used for name resolution.
258 See option
<option>UseDomains=
</option> below.
</para>
260 <para>See the
<literal>[DHCPv4]
</literal> or
<literal>[DHCPv6]
</literal> section below for
261 further configuration options for the DHCP client support.
</para>
265 <term><varname>DHCPServer=
</varname></term>
267 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started. Defaults
268 to
<literal>no
</literal>. Further settings for the DHCP
269 server may be set in the
<literal>[DHCPServer]
</literal>
270 section described below.
</para>
274 <term><varname>LinkLocalAddressing=
</varname></term>
276 <para>Enables link-local address autoconfiguration. Accepts
<literal>yes
</literal>,
277 <literal>no
</literal>,
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
278 <literal>fallback
</literal>, or
<literal>ipv4-fallback
</literal>. If
279 <literal>fallback
</literal> or
<literal>ipv4-fallback
</literal> is specified, then an IPv4
280 link-local address is configured only when DHCPv4 fails. If
<literal>fallback
</literal>,
281 an IPv6 link-local address is always configured, and if
<literal>ipv4-fallback
</literal>,
282 the address is not configured. Note that, the fallback mechanism works only when DHCPv4
283 client is enabled, that is, it requires
<literal>DHCP=yes
</literal> or
284 <literal>DHCP=ipv4
</literal>. If
<varname>Bridge=
</varname> is set, defaults to
285 <literal>no
</literal>, and if not, defaults to
<literal>ipv6
</literal>.
290 <term><varname>IPv4LLRoute=
</varname></term>
292 <para>Takes a boolean. If set to true, sets up the route needed for
293 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
299 <term><varname>DefaultRouteOnDevice=
</varname></term>
301 <para>Takes a boolean. If set to true, sets up the default route bound to the interface.
302 Defaults to false. This is useful when creating routes on point-to-point interfaces.
303 This is equivalent to e.g. the following.
304 <programlisting>ip route add default dev veth99
</programlisting></para>
308 <term><varname>IPv6Token=
</varname></term>
310 <para>An IPv6 address with the top
64 bits unset. When set, indicates the
311 64-bit interface part of SLAAC IPv6 addresses for this link. Note that
312 the token is only ever used for SLAAC, and not for DHCPv6 addresses, even
313 in the case DHCP is requested by router advertisement. By default, the
314 token is autogenerated.
</para>
318 <term><varname>LLMNR=
</varname></term>
320 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
322 url=
"https://tools.ietf.org/html/rfc4795">Link-Local
323 Multicast Name Resolution
</ulink> on the link. When set to
324 <literal>resolve
</literal>, only resolution is enabled,
325 but not host registration and announcement. Defaults to
326 true. This setting is read by
327 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
331 <term><varname>MulticastDNS=
</varname></term>
333 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
335 url=
"https://tools.ietf.org/html/rfc6762">Multicast
336 DNS
</ulink> support on the link. When set to
337 <literal>resolve
</literal>, only resolution is enabled,
338 but not host or service registration and
339 announcement. Defaults to false. This setting is read by
340 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
344 <term><varname>DNSOverTLS=
</varname></term>
346 <para>Takes a boolean or
<literal>opportunistic
</literal>.
349 url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink>
351 When set to
<literal>opportunistic
</literal>, compatibility with
352 non-DNS-over-TLS servers is increased, by automatically
353 turning off DNS-over-TLS servers in this case.
354 This option defines a per-interface setting for
355 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
356 global
<varname>DNSOverTLS=
</varname> option. Defaults to
357 false. This setting is read by
358 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
362 <term><varname>DNSSEC=
</varname></term>
364 <para>Takes a boolean. or
365 <literal>allow-downgrade
</literal>. When true, enables
367 url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink>
368 DNS validation support on the link. When set to
369 <literal>allow-downgrade
</literal>, compatibility with
370 non-DNSSEC capable networks is increased, by automatically
371 turning off DNSSEC in this case. This option defines a
372 per-interface setting for
373 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
374 global
<varname>DNSSEC=
</varname> option. Defaults to
375 false. This setting is read by
376 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
380 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
381 <listitem><para>A space-separated list of DNSSEC negative
382 trust anchor domains. If specified and DNSSEC is enabled,
383 look-ups done via the interface's DNS server will be subject
384 to the list of negative trust anchors, and not require
385 authentication for the specified domains, or anything below
386 it. Use this to disable DNSSEC authentication for specific
387 private domains, that cannot be proven valid using the
388 Internet DNS hierarchy. Defaults to the empty list. This
390 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
394 <term><varname>LLDP=
</varname></term>
396 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
397 implemented on professional routers and bridges which announces which physical port a system is connected
398 to, as well as other related data. Accepts a boolean or the special value
399 <literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
400 neighbors maintained. If
<literal>routers-only
</literal> is set only LLDP data of various types of routers
401 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
402 others). If false, LLDP reception is disabled. Defaults to
<literal>routers-only
</literal>. Use
403 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
404 collected neighbor data. LLDP is only available on Ethernet links. See
<varname>EmitLLDP=
</varname> below
405 for enabling LLDP packet emission from the local system.
410 <term><varname>EmitLLDP=
</varname></term>
412 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
413 <literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
414 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
415 a short LLDP packet with information about the local system is sent out in regular intervals on the
416 link. The LLDP packet will contain information about the local host name, the local machine ID (as stored
417 in
<citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
418 local interface name, as well as the pretty hostname of the system (as set in
419 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
420 emission is only available on Ethernet links. Note that this setting passes data suitable for
421 identification of host to the network and should thus not be enabled on untrusted networks, where such
422 identification data should not be made available. Use this option to permit other systems to identify on
423 which interfaces they are connected to this system. The three special values control propagation of the
424 LLDP packets. The
<literal>nearest-bridge
</literal> setting permits propagation only to the nearest
425 connected bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays, but
426 not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until a customer bridge
427 is reached. For details about these concepts, see
<ulink
428 url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>. Note that
429 configuring this setting to true is equivalent to
<literal>nearest-bridge
</literal>, the recommended and
430 most restricted level of propagation. See
<varname>LLDP=
</varname> above for an option to enable LLDP
435 <term><varname>BindCarrier=
</varname></term>
437 <para>A link name or a list of link names. When set, controls the behavior of the current
438 link. When all links in the list are in an operational down state, the current link is brought
439 down. When at least one link has carrier, the current interface is brought up.
444 <term><varname>Address=
</varname></term>
446 <para>A static IPv4 or IPv6 address and its prefix length,
447 separated by a
<literal>/
</literal> character. Specify
448 this key more than once to configure several addresses.
449 The format of the address must be as described in
450 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
451 This is a short-hand for an [Address] section only
452 containing an Address key (see below). This option may be
453 specified more than once.
456 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
457 (for IPv6), a new address range of the requested size is automatically allocated from a
458 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
459 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
460 all known network configuration files to avoid address range conflicts. The default system-wide
461 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.
462 This functionality is useful to manage a large number of dynamically created network interfaces
463 with the same network configuration and automatic address range assignment.
</para>
468 <term><varname>Gateway=
</varname></term>
470 <para>The gateway address, which must be in the format
472 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
473 This is a short-hand for a [Route] section only containing
474 a Gateway key. This option may be specified more than
479 <term><varname>DNS=
</varname></term>
481 <para>A DNS server address, which must be in the format
483 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
484 This option may be specified more than once. This setting is read by
485 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
489 <term><varname>Domains=
</varname></term>
491 <para>A list of domains which should be resolved using the DNS servers on this link. Each item in the list
492 should be a domain name, optionally prefixed with a tilde (
<literal>~
</literal>). The domains with the
493 prefix are called
"routing-only domains". The domains without the prefix are called
"search domains" and
494 are first used as search suffixes for extending single-label host names (host names containing no dots) to
495 become fully qualified domain names (FQDNs). If a single-label host name is resolved on this interface,
496 each of the specified search domains are appended to it in turn, converting it into a fully qualified
497 domain name, until one of them may be successfully resolved.
</para>
499 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for host names
500 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
501 the DNS servers configured for this interface. The domain routing logic is particularly useful on
502 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
504 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
505 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
506 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
507 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
508 if a link on which they are connected is available.
</para>
510 <para>This setting is read by
511 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
512 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
513 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
514 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
515 name servers limited to a specific link.
</para>
519 <term><varname>DNSDefaultRoute=
</varname></term>
521 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
522 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
523 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
524 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
525 queries not matching any link's configured domains will be routed to this link if it has no routing-only
526 domains configured.
</para>
530 <term><varname>NTP=
</varname></term>
532 <para>An NTP server address. This option may be specified more than once. This setting is read by
533 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
537 <term><varname>IPForward=
</varname></term>
538 <listitem><para>Configures IP packet forwarding for the
539 system. If enabled, incoming packets on any network
540 interface will be forwarded to any other interfaces
541 according to the routing table. Takes a boolean,
542 or the values
<literal>ipv4
</literal> or
543 <literal>ipv6
</literal>, which only enable IP packet
544 forwarding for the specified address family. This controls
545 the
<filename>net.ipv4.ip_forward
</filename> and
546 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
547 options of the network interface (see
<ulink
548 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
549 for details about sysctl options). Defaults to
550 <literal>no
</literal>.
</para>
552 <para>Note: this setting controls a global kernel option,
553 and does so one way only: if a network that has this setting
554 enabled is set up the global setting is turned on. However,
555 it is never turned off again, even after all networks with
556 this setting enabled are shut down again.
</para>
558 <para>To allow IP packet forwarding only between specific
559 network interfaces use a firewall.
</para>
563 <term><varname>IPMasquerade=
</varname></term>
564 <listitem><para>Configures IP masquerading for the network
565 interface. If enabled, packets forwarded from the network
566 interface will be appear as coming from the local host.
567 Takes a boolean argument. Implies
568 <varname>IPForward=ipv4
</varname>. Defaults to
569 <literal>no
</literal>.
</para></listitem>
572 <term><varname>IPv6PrivacyExtensions=
</varname></term>
573 <listitem><para>Configures use of stateless temporary
574 addresses that change over time (see
<ulink
575 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
576 Privacy Extensions for Stateless Address Autoconfiguration
577 in IPv6). Takes a boolean or the special values
578 <literal>prefer-public
</literal> and
579 <literal>kernel
</literal>. When true, enables the privacy
580 extensions and prefers temporary addresses over public
581 addresses. When
<literal>prefer-public
</literal>, enables the
582 privacy extensions, but prefers public addresses over
583 temporary addresses. When false, the privacy extensions
584 remain disabled. When
<literal>kernel
</literal>, the kernel's
585 default setting will be left in place. Defaults to
586 <literal>no
</literal>.
</para></listitem>
589 <term><varname>IPv6AcceptRA=
</varname></term>
590 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support
591 for the interface. If true, RAs are accepted; if false, RAs are ignored, independently of the
592 local forwarding state. When RAs are accepted, they may trigger the start of the DHCPv6
593 client if the relevant flags are set in the RA data, or if no routers are found on the link.
</para>
595 <para>Further settings for the IPv6 RA support may be configured in the
596 <literal>[IPv6AcceptRA]
</literal> section, see below.
</para>
598 <para>Also see
<ulink
599 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink> in the kernel
600 documentation regarding
<literal>accept_ra
</literal>, but note that systemd's setting of
601 <constant>1</constant> (i.e. true) corresponds to kernel's setting of
<constant>2</constant>.
</para>
603 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
604 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
605 RA protocol is used, and the kernel's own implementation remains disabled, since
606 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
607 and these are not available from the kernel if the kernel's own implementation is used.
</para>
611 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
612 <listitem><para>Configures the amount of IPv6 Duplicate
613 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
617 <term><varname>IPv6HopLimit=
</varname></term>
618 <listitem><para>Configures IPv6 Hop Limit. For each router that
619 forwards the packet, the hop limit is decremented by
1. When the
620 hop limit field reaches zero, the packet is discarded.
621 When unset, the kernel's default will be used.
625 <term><varname>IPv4ProxyARP=
</varname></term>
626 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
627 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
628 the router accepts responsibility for routing packets to the
"real" destination. (see
<ulink
629 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
630 When unset, the kernel's default will be used.
634 <term><varname>IPv6ProxyNDP=
</varname></term>
635 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
636 Protocol) is a technique for IPv6 to allow routing of addresses to a different
637 destination when peers expect them to be present on a certain physical link.
638 In this case a router answers Neighbour Advertisement messages intended for
639 another machine by offering its own MAC address as destination.
640 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
641 Advertisement messages for addresses in the IPv6 neighbor proxy table,
642 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
643 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
644 interface depending on this option.
645 When unset, the kernel's default will be used.
649 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
650 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
651 proxied. This option may be specified more than once. systemd-networkd will add the
652 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
653 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
654 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
658 <term><varname>IPv6PrefixDelegation=
</varname></term>
659 <listitem><para>Whether to enable or disable Router Advertisement sending on a link.
660 Allowed values are
<literal>static
</literal> which distributes prefixes as defined in
661 the
<literal>[IPv6PrefixDelegation]
</literal> and any
<literal>[IPv6Prefix]
</literal>
662 sections,
<literal>dhcpv6
</literal> which requests prefixes using a DHCPv6 client
663 configured for another link and any values configured in the
664 <literal>[IPv6PrefixDelegation]
</literal> section while ignoring all static prefix
665 configuration sections,
<literal>yes
</literal> which uses both static configuration
666 and DHCPv6, and
<literal>false
</literal> which turns off IPv6 prefix delegation
667 altogether. Defaults to
<literal>false
</literal>. See the
668 <literal>[IPv6PrefixDelegation]
</literal> and the
<literal>[IPv6Prefix]
</literal>
669 sections for more configuration options.
673 <term><varname>IPv6MTUBytes=
</varname></term>
674 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
675 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
679 <term><varname>Bridge=
</varname></term>
681 <para>The name of the bridge to add the link to. See
682 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
687 <term><varname>Bond=
</varname></term>
689 <para>The name of the bond to add the link to. See
690 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
695 <term><varname>VRF=
</varname></term>
697 <para>The name of the VRF to add the link to. See
698 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
703 <term><varname>VLAN=
</varname></term>
705 <para>The name of a VLAN to create on the link. See
706 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
707 This option may be specified more than once.
</para>
711 <term><varname>IPVLAN=
</varname></term>
713 <para>The name of a IPVLAN to create on the link. See
714 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
715 This option may be specified more than once.
</para>
719 <term><varname>MACVLAN=
</varname></term>
721 <para>The name of a MACVLAN to create on the link. See
722 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
723 This option may be specified more than once.
</para>
727 <term><varname>VXLAN=
</varname></term>
729 <para>The name of a VXLAN to create on the link. See
730 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
731 This option may be specified more than once.
</para>
735 <term><varname>Tunnel=
</varname></term>
737 <para>The name of a Tunnel to create on the link. See
738 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
739 This option may be specified more than once.
</para>
743 <term><varname>MACsec=
</varname></term>
745 <para>The name of a MACsec device to create on the link. See
746 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
747 This option may be specified more than once.
</para>
751 <term><varname>ActiveSlave=
</varname></term>
753 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
754 option is only valid for following modes:
755 <literal>active-backup
</literal>,
756 <literal>balance-alb
</literal> and
757 <literal>balance-tlb
</literal>. Defaults to false.
762 <term><varname>PrimarySlave=
</varname></term>
764 <para>Takes a boolean. Specifies which slave is the primary device. The specified
765 device will always be the active slave while it is available. Only when the
766 primary is off-line will alternate devices be used. This is useful when
767 one slave is preferred over another, e.g. when one slave has higher throughput
768 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
770 <literal>active-backup
</literal>,
771 <literal>balance-alb
</literal> and
772 <literal>balance-tlb
</literal>. Defaults to false.
777 <term><varname>ConfigureWithoutCarrier=
</varname></term>
779 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
785 <term><varname>IgnoreCarrierLoss=
</varname></term>
787 <para>A boolean. Allows networkd to retain both the static and dynamic configuration of the
788 interface even if its carrier is lost. Defaults to false.
793 <term><varname>Xfrm=
</varname></term>
795 <para>The name of the xfrm to create on the link. See
796 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
797 This option may be specified more than once.
</para>
801 <term><varname>KeepConfiguration=
</varname></term>
803 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
804 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
805 will not drop static addresses and routes on starting up process. When set to
806 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
807 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
808 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
809 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
810 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
811 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
812 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
<literal>no
</literal>.
822 <title>[Address] Section Options
</title>
824 <para>An
<literal>[Address]
</literal> section accepts the
825 following keys. Specify several
<literal>[Address]
</literal>
826 sections to configure several addresses.
</para>
828 <variablelist class='network-directives'
>
830 <term><varname>Address=
</varname></term>
832 <para>As in the
<literal>[Network]
</literal> section. This key is mandatory. Each
833 <literal>[Address]
</literal> section can contain one
<varname>Address=
</varname> setting.
</para>
837 <term><varname>Peer=
</varname></term>
839 <para>The peer address in a point-to-point connection.
840 Accepts the same format as the
<varname>Address=
</varname>
845 <term><varname>Broadcast=
</varname></term>
847 <para>The broadcast address, which must be in the format
849 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
850 This key only applies to IPv4 addresses. If it is not
851 given, it is derived from the
<varname>Address=
</varname>
856 <term><varname>Label=
</varname></term>
858 <para>An address label.
</para>
862 <term><varname>PreferredLifetime=
</varname></term>
864 <para>Allows the default
"preferred lifetime" of the address to be overridden.
865 Only three settings are accepted:
<literal>forever
</literal> or
<literal>infinity
</literal>
866 which is the default and means that the address never expires, and
<literal>0</literal> which means
867 that the address is considered immediately
"expired" and will not be used,
868 unless explicitly requested. A setting of PreferredLifetime=
0 is useful for
869 addresses which are added to be used only by a specific application,
870 which is then configured to use them explicitly.
</para>
874 <term><varname>Scope=
</varname></term>
876 <para>The scope of the address, which can be
<literal>global
</literal>,
877 <literal>link
</literal> or
<literal>host
</literal> or an unsigned integer ranges
0 to
255.
878 Defaults to
<literal>global
</literal>.
</para>
882 <term><varname>HomeAddress=
</varname></term>
884 <para>Takes a boolean. Designates this address the
"home address" as defined in
885 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
886 Supported only on IPv6. Defaults to false.
</para>
890 <term><varname>DuplicateAddressDetection=
</varname></term>
892 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
893 <literal>both
</literal>,
<literal>none
</literal>. When
<literal>ipv4
</literal>,
894 performs IPv4 Duplicate Address Detection. See
895 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
896 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
897 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>.
898 Defaults to
<literal>ipv6
</literal>.
</para>
902 <term><varname>ManageTemporaryAddress=
</varname></term>
904 <para>Takes a boolean. If true the kernel manage temporary addresses created
905 from this one as template on behalf of Privacy Extensions
906 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
907 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
908 The given address needs to have a prefix length of
64. This flag allows using privacy
909 extensions in a manually configured network, just like if stateless auto-configuration
910 was active. Defaults to false.
</para>
914 <term><varname>AddPrefixRoute=
</varname></term>
916 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
917 Defaults to true.
</para>
921 <term><varname>AutoJoin=
</varname></term>
923 <para>Takes a boolean. Joining multicast group on ethernet level via
924 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
925 IGMP snooping since the switch would not replicate multicast packets on ports that did not
926 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
927 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
928 that enables then to do the required join. By extending ip address command with option
929 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
930 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
931 Defaults to
<literal>no
</literal>.
</para>
938 <title>[Neighbor] Section Options
</title>
939 <para>A
<literal>[Neighbor]
</literal> section accepts the
940 following keys. The neighbor section adds a permanent, static
941 entry to the neighbor table (IPv6) or ARP table (IPv4) for
942 the given hardware address on the links matched for the network.
943 Specify several
<literal>[Neighbor]
</literal> sections to configure
944 several static neighbors.
</para>
946 <variablelist class='network-directives'
>
948 <term><varname>Address=
</varname></term>
950 <para>The IP address of the neighbor.
</para>
954 <term><varname>LinkLayerAddress=
</varname></term>
956 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
963 <title>[IPv6AddressLabel] Section Options
</title>
965 <para>An
<literal>[IPv6AddressLabel]
</literal> section accepts the
966 following keys. Specify several
<literal>[IPv6AddressLabel]
</literal>
967 sections to configure several address labels. IPv6 address labels are
968 used for address selection. See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>.
969 Precedence is managed by userspace, and only the label itself is stored in the kernel
</para>
971 <variablelist class='network-directives'
>
973 <term><varname>Label=
</varname></term>
975 <para> The label for the prefix (an unsigned integer) ranges
0 to
4294967294.
976 0xffffffff is reserved. This key is mandatory.
</para>
980 <term><varname>Prefix=
</varname></term>
982 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
983 This key is mandatory.
</para>
990 <title>[RoutingPolicyRule] Section Options
</title>
992 <para>An
<literal>[RoutingPolicyRule]
</literal> section accepts the
993 following keys. Specify several
<literal>[RoutingPolicyRule]
</literal>
994 sections to configure several rules.
</para>
996 <variablelist class='network-directives'
>
998 <term><varname>TypeOfService=
</varname></term>
1000 <para>Specifies the type of service to match a number between
0 to
255.
</para>
1004 <term><varname>From=
</varname></term>
1006 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1010 <term><varname>To=
</varname></term>
1012 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1016 <term><varname>FirewallMark=
</varname></term>
1018 <para>Specifies the iptables firewall mark value to match (a number between
1 and
4294967295).
</para>
1022 <term><varname>Table=
</varname></term>
1024 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes
1025 one of
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
1026 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1030 <term><varname>Priority=
</varname></term>
1032 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1033 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1037 <term><varname>IncomingInterface=
</varname></term>
1039 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1043 <term><varname>OutgoingInterface=
</varname></term>
1045 <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>
1049 <term><varname>SourcePort=
</varname></term>
1051 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1052 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1056 <term><varname>DestinationPort=
</varname></term>
1058 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1059 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1063 <term><varname>IPProtocol=
</varname></term>
1065 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1066 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1067 <literal>17</literal> for
<literal>udp
</literal>.
1068 Defaults to unset.
</para>
1072 <term><varname>InvertRule=
</varname></term>
1074 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1078 <term><varname>Family=
</varname></term>
1080 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1081 <literal>both
</literal>. By default, the address family is determined by the address
1082 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1083 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1084 <literal>ipv4
</literal>.
</para>
1088 <term><varname>User=
</varname></term>
1090 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1095 <term><varname>SuppressPrefixLength=
</varname></term>
1097 <para>Takes a number
<replaceable>N
</replaceable> in the range
0-
128 and rejects routing
1098 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1106 <title>[NextHop] Section Options
</title>
1107 <para>The
<literal>[NextHop]
</literal> section accepts the
1108 following keys. Specify several
<literal>[NextHop]
</literal>
1109 sections to configure several nexthop. Nexthop is used to manipulate entries in the kernel's nexthop
1112 <variablelist class='network-directives'
>
1114 <term><varname>Gateway=
</varname></term>
1116 <para>As in the
<literal>[Network]
</literal> section. This is mandatory.
</para>
1120 <term><varname>Id=
</varname></term>
1122 <para>The id of the nexthop (an unsigned integer). If unspecified or '
0' then automatically chosen by kernel.
</para>
1129 <title>[Route] Section Options
</title>
1130 <para>The
<literal>[Route]
</literal> section accepts the
1131 following keys. Specify several
<literal>[Route]
</literal>
1132 sections to configure several routes.
</para>
1134 <variablelist class='network-directives'
>
1136 <term><varname>Gateway=
</varname></term>
1138 <para>Takes the gateway address or special value
<literal>dhcp
</literal>. If
1139 <literal>dhcp
</literal>, then the gateway address provided by DHCP (or in the IPv6 case,
1140 provided by IPv6 RA) is used.
</para>
1144 <term><varname>GatewayOnLink=
</varname></term>
1146 <para>Takes a boolean. If set to true, the kernel does not have
1147 to check if the gateway is reachable directly by the current machine (i.e., the kernel does
1148 not need to check if the gateway is attached to the local network), so that we can insert the
1149 route in the kernel table without it being complained about. Defaults to
<literal>no
</literal>.
1154 <term><varname>Destination=
</varname></term>
1156 <para>The destination prefix of the route. Possibly
1157 followed by a slash and the prefix length. If omitted, a
1158 full-length host route is assumed.
</para>
1162 <term><varname>Source=
</varname></term>
1164 <para>The source prefix of the route. Possibly followed by
1165 a slash and the prefix length. If omitted, a full-length
1166 host route is assumed.
</para>
1170 <term><varname>Metric=
</varname></term>
1172 <para>The metric of the route (an unsigned integer).
</para>
1176 <term><varname>IPv6Preference=
</varname></term>
1178 <para>Specifies the route preference as defined in
<ulink
1179 url=
"https://tools.ietf.org/html/rfc4191">RFC4191
</ulink> for Router Discovery messages.
1180 Which can be one of
<literal>low
</literal> the route has a lowest priority,
1181 <literal>medium
</literal> the route has a default priority or
1182 <literal>high
</literal> the route has a highest priority.
</para>
1186 <term><varname>Scope=
</varname></term>
1188 <para>The scope of the route, which can be
<literal>global
</literal>,
<literal>site
</literal>,
1189 <literal>link
</literal>,
<literal>host
</literal>, or
<literal>nowhere
</literal>. For IPv4 route,
1190 defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
<literal>local
</literal>
1191 or
<literal>nat
</literal>, and
<literal>link
</literal> if
<varname>Type=
</varname> is
1192 <literal>broadcast
</literal>,
<literal>multicast
</literal>, or
<literal>anycast
</literal>.
1193 In other cases, defaults to
<literal>global
</literal>.
</para>
1197 <term><varname>PreferredSource=
</varname></term>
1199 <para>The preferred source address of the route. The address
1200 must be in the format described in
1201 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1205 <term><varname>Table=
</varname></term>
1207 <para>The table identifier for the route. Takes
<literal>default
</literal>,
1208 <literal>main
</literal>,
<literal>local
</literal> or a number between
1 and
4294967295.
1209 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1210 If unset and
<varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1211 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1212 In other cases, defaults to
<literal>main
</literal>.
1217 <term><varname>Protocol=
</varname></term>
1219 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1220 <literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1221 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1226 <term><varname>Type=
</varname></term>
1228 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1229 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1230 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1231 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1232 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1233 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1234 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1235 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1236 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1237 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1238 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1243 <term><varname>InitialCongestionWindow=
</varname></term>
1245 <para>The TCP initial congestion window is used during the start of a TCP connection. During the start of a TCP
1246 session, when a client requests a resource, the server's initial congestion window determines how many data bytes
1247 will be sent during the initial burst of data. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual
1248 suffixes K, M, G are supported and are understood to the base of
1024. When unset, the kernel's default will be used.
1253 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1255 <para>The TCP initial advertised receive window is the amount of receive data (in bytes) that can initially be buffered at one time
1256 on a connection. The sending host can send only that amount of data before waiting for an acknowledgment and window update
1257 from the receiving host. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual suffixes K, M, G are supported
1258 and are understood to the base of
1024. When unset, the kernel's default will be used.
1263 <term><varname>QuickAck=
</varname></term>
1265 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1270 <term><varname>FastOpenNoCookie=
</varname></term>
1272 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1273 When unset, the kernel's default will be used.
1278 <term><varname>TTLPropagate=
</varname></term>
1280 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1281 When unset, the kernel's default will be used.
1286 <term><varname>MTUBytes=
</varname></term>
1288 <para>The maximum transmission unit in bytes to set for the
1289 route. The usual suffixes K, M, G, are supported and are
1290 understood to the base of
1024.
</para>
1291 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1292 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1296 <term><varname>IPServiceType=
</varname></term>
1298 <para>Takes string;
<literal>CS6
</literal> or
<literal>CS4
</literal>. Used to set IP
1299 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.
</para>
1303 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1305 <para>Configures multipath route. Multipath routing is the technique of using multiple
1306 alternative paths through a network. Takes gateway address. Optionally, takes a network
1307 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for
1308 this multipath route separated with whitespace. This setting can be specified multiple
1309 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
1316 <title>[DHCPv4] Section Options
</title>
1317 <para>The
<literal>[DHCPv4]
</literal> section configures the
1318 DHCPv4 client, if it is enabled with the
1319 <varname>DHCP=
</varname> setting described above:
</para>
1321 <variablelist class='network-directives'
>
1323 <term><varname>UseDNS=
</varname></term>
1325 <para>When true (the default), the DNS servers received
1326 from the DHCP server will be used and take precedence over
1327 any statically configured ones.
</para>
1329 <para>This corresponds to the
<option>nameserver
</option>
1330 option in
<citerefentry
1331 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1335 <term><varname>RoutesToDNS=
</varname></term>
1337 <para>When true, the routes to the DNS servers received from the DHCP server will be
1338 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored.
1339 Defaults to false.
</para>
1343 <term><varname>UseNTP=
</varname></term>
1345 <para>When true (the default), the NTP servers received
1346 from the DHCP server will be used by systemd-timesyncd
1347 and take precedence over any statically configured ones.
</para>
1351 <term><varname>UseSIP=
</varname></term>
1353 <para>When true (the default), the SIP servers received
1354 from the DHCP server will be saved at the state files and can be
1355 read via
<function>sd_network_link_get_sip_servers()
</function> function.
</para>
1359 <term><varname>UseMTU=
</varname></term>
1361 <para>When true, the interface maximum transmission unit
1362 from the DHCP server will be used on the current link.
1363 If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
1364 Defaults to false.
</para>
1368 <term><varname>Anonymize=
</varname></term>
1370 <para>Takes a boolean. When true, the options sent to the DHCP server will
1371 follow the
<ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink>
1372 (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying information.
1373 Defaults to false.
</para>
1375 <para>This option should only be set to true when
1376 <varname>MACAddressPolicy=
</varname> is set to
<literal>random
</literal>
1378 project='man-pages'
><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
1380 <para>Note that this configuration will overwrite others.
1381 In concrete, the following variables will be ignored:
1382 <varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1383 <varname>UseRoutes=
</varname>,
<varname>UseMTU=
</varname>,
1384 <varname>VendorClassIdentifier=
</varname>,
<varname>UseTimezone=
</varname>.
</para>
1386 <para>With this option enabled DHCP requests will mimic those generated by Microsoft Windows, in
1387 order to reduce the ability to fingerprint and recognize installations. This means DHCP request
1388 sizes will grow and lease data will be more comprehensive than normally, though most of the
1389 requested data is not actually used.
</para>
1393 <term><varname>SendHostname=
</varname></term>
1395 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1396 Note that the machine's hostname must consist only of
7-bit ASCII lower-case characters and
1397 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1398 sent even if this is set to true.
</para>
1402 <term><varname>UseHostname=
</varname></term>
1404 <para>When true (the default), the hostname received from
1405 the DHCP server will be set as the transient hostname of the system.
1410 <term><varname>Hostname=
</varname></term>
1412 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1413 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1414 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1418 <term><varname>UseDomains=
</varname></term>
1420 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1421 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1422 the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name received from
1423 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1424 the
<option>Domains=
</option> setting when the argument is prefixed with
<literal>~
</literal>. Defaults to
1427 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1428 of all host names, in particular of single-label names. It is generally safer to use the supplied domain
1429 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1430 single-label names.
</para>
1432 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1433 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1437 <term><varname>UseRoutes=
</varname></term>
1439 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1440 routing table with a metric of
1024, and a scope of
"global",
"link" or
"host", depending on the route's
1441 destination and gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the
1442 link's own address, the scope will be set to
"host". Otherwise if the gateway is null (a direct route), a
1443 "link" scope will be used. For anything else, scope defaults to
"global".
</para>
1448 <term><varname>UseTimezone=
</varname></term>
1450 <listitem><para>When true, the timezone received from the
1451 DHCP server will be set as timezone of the local
1452 system. Defaults to
<literal>no
</literal>.
</para></listitem>
1456 <term><varname>ClientIdentifier=
</varname></term>
1458 <para>The DHCPv4 client identifier to use. Takes one of
<literal>mac
</literal>,
<literal>duid
</literal> or
<literal>duid-only
</literal>.
1459 If set to
<literal>mac
</literal>, the MAC address of the link is used.
1460 If set to
<literal>duid
</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1461 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.
1462 Defaults to
<literal>duid
</literal>.
</para>
1467 <term><varname>VendorClassIdentifier=
</varname></term>
1469 <para>The vendor class identifier used to identify vendor
1470 type and configuration.
</para>
1475 <term><varname>UserClass=
</varname></term>
1477 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1478 it represents. The information contained in this option is a string that represents the user class of which
1479 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1480 service to classify clients. Takes a whitespace-separated list of strings.
</para>
1485 <term><varname>MaxAttempts=
</varname></term>
1487 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1488 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>.
1489 Note that the time between retries is increased exponentially, so the network will not be
1490 overloaded even if this number is high.
</para>
1495 <term><varname>DUIDType=
</varname></term>
1497 <para>Override the global
<varname>DUIDType
</varname> setting for this network. See
1498 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1499 for a description of possible values.
</para>
1504 <term><varname>DUIDRawData=
</varname></term>
1506 <para>Override the global
<varname>DUIDRawData
</varname> setting for this network. See
1507 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1508 for a description of possible values.
</para>
1513 <term><varname>IAID=
</varname></term>
1515 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned integer.
</para>
1520 <term><varname>RequestBroadcast=
</varname></term>
1522 <para>Request the server to use broadcast messages before
1523 the IP address has been configured. This is necessary for
1524 devices that cannot receive RAW packets, or that cannot
1525 receive packets at all before an IP address has been
1526 configured. On the other hand, this must not be enabled on
1527 networks where broadcasts are filtered out.
</para>
1532 <term><varname>RouteMetric=
</varname></term>
1534 <para>Set the routing metric for routes specified by the
1540 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1542 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1543 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1545 <para>When used in combination with
<varname>VRF=
</varname> the
1546 VRF's routing table is used unless this parameter is specified.
1552 <term><varname>RouteMTUBytes=
</varname></term>
1554 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.
</para>
1559 <term><varname>ListenPort=
</varname></term>
1561 <para>Allow setting custom port for the DHCP client to listen on.
</para>
1566 <term><varname>SendRelease=
</varname></term>
1568 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops.
1569 Defaults to true.
</para>
1574 <term><varname>SendDecline=
</varname></term>
1576 <para>A boolen. When
<literal>true
</literal>, DHCPv4 clients receives IP address from DHCP server.
1577 After new IP is received, DHCPv4 performs IPv4 Duplicate Address Detection. If duplicate use of IP is detected
1578 the DHCPv4 client rejects the IP by sending a DHCPDECLINE packet DHCP clients try to obtain an IP address again.
1579 See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
1580 Defaults to
<literal>unset
</literal>.
</para>
1585 <term><varname>BlackList=
</varname></term>
1587 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are rejected.
</para>
1592 <term><varname>RequestOptions=
</varname></term>
1594 <para>A whitespace-separated list of integers in the range
1–
254.
</para>
1599 <term><varname>SendOption=
</varname></term>
1601 <para>Send an arbitrary option in the DHCPv4 request. Takes a DHCP option number, data type
1602 and data separated with a colon
1603 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1604 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1605 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1606 <literal>string
</literal>. Special characters in the data string may be escaped using
1607 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1608 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1609 then all options specified earlier are cleared. Defaults to unset.
</para>
1616 <title>[DHCPv6] Section Options
</title>
1617 <para>The
<literal>[DHCPv6]
</literal> section configures the DHCPv6 client, if it is enabled with the
1618 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
</para>
1620 <variablelist class='network-directives'
>
1622 <term><varname>UseDNS=
</varname></term>
1623 <term><varname>UseNTP=
</varname></term>
1625 <para>As in the
<literal>[DHCPv4]
</literal> section.
</para>
1630 <term><varname>RapidCommit=
</varname></term>
1632 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1633 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1634 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1635 four-method exchange (solicit, advertise, request, and reply). The two-message exchange provides
1636 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1637 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
1638 Defaults to true.
</para>
1643 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
1645 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
1646 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
1647 makes DHCPv6 request network information in a stateless manner using a two-message Information
1648 Request and Information Reply message exchange.
1649 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
1650 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
1651 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
1652 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
1653 By default this option is set to 'false', enable it if no prefixes are delegated when the device
1654 should be acting as a CE router.
</para>
1659 <term><varname>PrefixDelegationHint=
</varname></term>
1661 <para>Takes an IPv6 address with prefix length as
<varname>Address=
</varname> in
1662 the
"[Network]" section. Specifies the DHCPv6 client for the requesting router to include
1663 a prefix-hint in the DHCPv6 solicitation. Prefix ranges
1-
128. Defaults to unset.
</para>
1670 <title>[IPv6AcceptRA] Section Options
</title>
1671 <para>The
<literal>[IPv6AcceptRA]
</literal> section configures the IPv6 Router Advertisement
1672 (RA) client, if it is enabled with the
<varname>IPv6AcceptRA=
</varname> setting described
1675 <variablelist class='network-directives'
>
1677 <term><varname>UseDNS=
</varname></term>
1679 <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
1680 precedence over any statically configured ones.
</para>
1682 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
1683 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1688 <term><varname>UseDomains=
</varname></term>
1690 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1691 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
1692 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
1693 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
1694 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
1695 <literal>~
</literal>. Defaults to false.
</para>
1697 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1698 of all host names, in particular of single-label names. It is generally safer to use the supplied domain
1699 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1700 single-label names.
</para>
1702 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1703 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1708 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1710 <para>The table identifier for the routes received in the Router Advertisement
1711 (a number between
1 and
4294967295, or
0 to unset).
1712 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1718 <term><varname>UseAutonomousPrefix=
</varname></term>
1720 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
1721 precedence over any statically configured ones.
</para>
1726 <term><varname>UseOnLinkPrefix=
</varname></term>
1728 <para>When true (the default), the onlink prefix received in the Router Advertisement will be used and take
1729 precedence over any statically configured ones.
</para>
1734 <term><varname>BlackList=
</varname></term>
1736 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router advertisements in the list are ignored.
</para>
1744 <title>[DHCPServer] Section Options
</title>
1745 <para>The
<literal>[DHCPServer]
</literal> section contains
1746 settings for the DHCP server, if enabled via the
1747 <varname>DHCPServer=
</varname> option described above:
</para>
1749 <variablelist class='network-directives'
>
1752 <term><varname>PoolOffset=
</varname></term>
1753 <term><varname>PoolSize=
</varname></term>
1755 <listitem><para>Configures the pool of addresses to hand out. The pool
1756 is a contiguous sequence of IP addresses in the subnet configured for
1757 the server address, which does not include the subnet nor the broadcast
1758 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
1759 from the start of subnet, or zero to use the default value.
1760 <varname>PoolSize=
</varname> takes the number of IP addresses in the
1761 pool or zero to use the default value. By default, the pool starts at
1762 the first address after the subnet address and takes up the rest of
1763 the subnet, excluding the broadcast address. If the pool includes
1764 the server address (the default), this is reserved and not handed
1765 out to clients.
</para></listitem>
1769 <term><varname>DefaultLeaseTimeSec=
</varname></term>
1770 <term><varname>MaxLeaseTimeSec=
</varname></term>
1772 <listitem><para>Control the default and maximum DHCP lease
1773 time to pass to clients. These settings take time values in seconds or
1774 another common time unit, depending on the suffix. The default
1775 lease time is used for clients that did not ask for a specific
1776 lease time. If a client asks for a lease time longer than the
1777 maximum lease time, it is automatically shortened to the
1778 specified time. The default lease time defaults to
1h, the
1779 maximum lease time to
12h. Shorter lease times are beneficial
1780 if the configuration data in DHCP leases changes frequently
1781 and clients shall learn the new settings with shorter
1782 latencies. Longer lease times reduce the generated DHCP
1783 network traffic.
</para></listitem>
1787 <term><varname>EmitDNS=
</varname></term>
1788 <term><varname>DNS=
</varname></term>
1790 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1791 to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
1792 The DNS servers to pass to clients may be configured with the
1793 <varname>DNS=
</varname> option, which takes a list of IPv4
1794 addresses. If the
<varname>EmitDNS=
</varname> option is
1795 enabled but no servers configured, the servers are
1796 automatically propagated from an
"uplink" interface that has
1797 appropriate servers set. The
"uplink" interface is determined
1798 by the default route of the system with the highest
1799 priority. Note that this information is acquired at the time
1800 the lease is handed out, and does not take uplink interfaces
1801 into account that acquire DNS or NTP server information at a
1802 later point. DNS server propagation does not take
1803 <filename>/etc/resolv.conf
</filename> into account. Also, note
1804 that the leases are not refreshed if the uplink network
1805 configuration changes. To ensure clients regularly acquire the
1806 most current uplink DNS server information, it is thus
1807 advisable to shorten the DHCP lease time via
1808 <varname>MaxLeaseTimeSec=
</varname> described
1809 above.
</para></listitem>
1813 <term><varname>EmitNTP=
</varname></term>
1814 <term><varname>NTP=
</varname></term>
1816 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1817 <varname>DNS=
</varname> settings described above, these
1818 settings configure whether and what NTP server information
1819 shall be emitted as part of the DHCP lease. The same syntax,
1820 propagation semantics and defaults apply as for
1821 <varname>EmitDNS=
</varname> and
1822 <varname>DNS=
</varname>.
</para></listitem>
1826 <term><varname>EmitSIP=
</varname></term>
1827 <term><varname>SIP=
</varname></term>
1829 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1830 <varname>DNS=
</varname> settings described above, these
1831 settings configure whether and what SIP server information
1832 shall be emitted as part of the DHCP lease. The same syntax,
1833 propagation semantics and defaults apply as for
1834 <varname>EmitDNS=
</varname> and
1835 <varname>DNS=
</varname>.
</para></listitem>
1839 <term><varname>EmitRouter=
</varname></term>
1841 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
1842 setting described above, this setting configures whether the
1843 DHCP lease should contain the router option. The same syntax,
1844 propagation semantics and defaults apply as for
1845 <varname>EmitDNS=
</varname>.
</para></listitem>
1849 <term><varname>EmitTimezone=
</varname></term>
1850 <term><varname>Timezone=
</varname></term>
1852 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1853 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
1854 <varname>Timezone=
</varname> setting takes a timezone string
1855 (such as
<literal>Europe/Berlin
</literal> or
1856 <literal>UTC
</literal>) to pass to clients. If no explicit
1857 timezone is set, the system timezone of the local host is
1858 propagated, as determined by the
1859 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
1863 <term><varname>SendOption=
</varname></term>
1865 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
1866 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1867 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1868 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1869 <literal>string
</literal>. Special characters in the data string may be escaped using
1870 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1871 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1872 then all options specified earlier are cleared. Defaults to unset.
</para>
1880 <title>[IPv6PrefixDelegation] Section Options
</title>
1881 <para>The
<literal>[IPv6PrefixDelegation]
</literal> section contains
1882 settings for sending IPv6 Router Advertisements and whether to act as
1883 a router, if enabled via the
<varname>IPv6PrefixDelegation=
</varname>
1884 option described above. IPv6 network prefixes are defined with one or
1885 more
<literal>[IPv6Prefix]
</literal> sections.
</para>
1887 <variablelist class='network-directives'
>
1890 <term><varname>Managed=
</varname></term>
1891 <term><varname>OtherInformation=
</varname></term>
1893 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
1894 addresses on the network link when
<varname>Managed=
</varname>
1895 is set to
<literal>true
</literal> or if only additional network
1896 information can be obtained via DHCPv6 for the network link when
1897 <varname>OtherInformation=
</varname> is set to
1898 <literal>true
</literal>. Both settings default to
1899 <literal>false
</literal>, which means that a DHCPv6 server is not being
1900 used.
</para></listitem>
1904 <term><varname>RouterLifetimeSec=
</varname></term>
1906 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. If set,
1907 this host also announces itself in Router Advertisements as an IPv6
1908 router for the network link. When unset, the host is not acting as a router.
</para>
1913 <term><varname>RouterPreference=
</varname></term>
1915 <listitem><para>Configures IPv6 router preference if
1916 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
1917 <literal>high
</literal>,
<literal>medium
</literal> and
1918 <literal>low
</literal>, with
<literal>normal
</literal> and
1919 <literal>default
</literal> added as synonyms for
1920 <literal>medium
</literal> just to make configuration easier. See
1921 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
1922 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
1926 <term><varname>EmitDNS=
</varname></term>
1927 <term><varname>DNS=
</varname></term>
1929 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
1930 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is
1931 true.
<varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that
1932 case the IPv6 link local address is distributed. If
<varname>DNS=
</varname> is empty, DNS
1933 servers are read from the
<literal>[Network]
</literal> section. If the
1934 <literal>[Network]
</literal> section does not contain any DNS servers either, DNS servers from
1935 the uplink with the highest priority default route are used. When
<varname>EmitDNS=
</varname>
1936 is false, no DNS server information is sent in Router Advertisement messages.
1937 <varname>EmitDNS=
</varname> defaults to true.
1942 <term><varname>EmitDomains=
</varname></term>
1943 <term><varname>Domains=
</varname></term>
1945 <listitem><para>A list of DNS search domains distributed via Router
1946 Advertisement messages when
<varname>EmitDomains=
</varname> is true. If
1947 <varname>Domains=
</varname> is empty, DNS search domains are read from the
1948 <literal>[Network]
</literal> section. If the
<literal>[Network]
</literal>
1949 section does not contain any DNS search domains either, DNS search
1950 domains from the uplink with the highest priority default route are
1951 used. When
<varname>EmitDomains=
</varname> is false, no DNS search domain
1952 information is sent in Router Advertisement messages.
1953 <varname>EmitDomains=
</varname> defaults to true.
1958 <term><varname>DNSLifetimeSec=
</varname></term>
1960 <listitem><para>Lifetime in seconds for the DNS server addresses listed
1961 in
<varname>DNS=
</varname> and search domains listed in
1962 <varname>Domains=
</varname>.
</para></listitem>
1969 <title>[IPv6Prefix] Section Options
</title>
1970 <para>One or more
<literal>[IPv6Prefix]
</literal> sections contain the IPv6
1971 prefixes that are announced via Router Advertisements. See
1972 <ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink>
1973 for further details.
</para>
1975 <variablelist class='network-directives'
>
1978 <term><varname>AddressAutoconfiguration=
</varname></term>
1979 <term><varname>OnLink=
</varname></term>
1981 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
1982 autoconfigured with this prefix and whether the prefix can be used for
1983 onlink determination. Both settings default to
<literal>true
</literal>
1984 in order to ease configuration.
1989 <term><varname>Prefix=
</varname></term>
1991 <listitem><para>The IPv6 prefix that is to be distributed to hosts.
1992 Similarly to configuring static IPv6 addresses, the setting is
1993 configured as an IPv6 prefix and its prefix length, separated by a
1994 <literal>/
</literal> character. Use multiple
1995 <literal>[IPv6Prefix]
</literal> sections to configure multiple IPv6
1996 prefixes since prefix lifetimes, address autoconfiguration and onlink
1997 status may differ from one prefix to another.
</para></listitem>
2001 <term><varname>PreferredLifetimeSec=
</varname></term>
2002 <term><varname>ValidLifetimeSec=
</varname></term>
2004 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2005 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
2006 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
2007 to
2592000 seconds (
30 days).
</para></listitem>
2014 <title>[IPv6RoutePrefix] Section Options
</title>
2015 <para>One or more
<literal>[IPv6RoutePrefix]
</literal> sections contain the IPv6
2016 prefix routes that are announced via Router Advertisements. See
2017 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2018 for further details.
</para>
2020 <variablelist class='network-directives'
>
2023 <term><varname>Route=
</varname></term>
2025 <listitem><para>The IPv6 route that is to be distributed to hosts.
2026 Similarly to configuring static IPv6 routes, the setting is
2027 configured as an IPv6 prefix routes and its prefix route length,
2028 separated by a
<literal>/
</literal> character. Use multiple
2029 <literal>[IPv6PrefixRoutes]
</literal> sections to configure multiple IPv6
2030 prefix routes.
</para></listitem>
2034 <term><varname>LifetimeSec=
</varname></term>
2036 <listitem><para>Lifetime for the route prefix measured in
2037 seconds.
<varname>LifetimeSec=
</varname> defaults to
604800 seconds (one week).
2045 <title>[Bridge] Section Options
</title>
2046 <para>The
<literal>[Bridge]
</literal> section accepts the
2047 following keys.
</para>
2048 <variablelist class='network-directives'
>
2050 <term><varname>UnicastFlood=
</varname></term>
2052 <para>Takes a boolean. Controls whether the bridge should flood
2053 traffic for which an FDB entry is missing and the destination
2054 is unknown through this port. When unset, the kernel's default will be used.
2059 <term><varname>MulticastFlood=
</varname></term>
2061 <para>Takes a boolean. Controls whether the bridge should flood
2062 traffic for which an MDB entry is missing and the destination
2063 is unknown through this port. When unset, the kernel's default will be used.
2068 <term><varname>MulticastToUnicast=
</varname></term>
2070 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2071 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2072 When unset, the kernel's default will be used.
2077 <term><varname>NeighborSuppression=
</varname></term>
2079 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2080 this port. When unset, the kernel's default will be used.
2085 <term><varname>Learning=
</varname></term>
2087 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2088 this port. When unset, the kernel's default will be used.
2093 <term><varname>HairPin=
</varname></term>
2095 <para>Takes a boolean. Configures whether traffic may be sent back
2096 out of the port on which it was received. When this flag is false, and the bridge
2097 will not forward traffic back out of the receiving port.
2098 When unset, the kernel's default will be used.
</para>
2102 <term><varname>UseBPDU=
</varname></term>
2104 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2105 processed by the bridge port. When unset, the kernel's default will be used.
</para>
2109 <term><varname>FastLeave=
</varname></term>
2111 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2112 traffic on a port that receives an IGMP Leave message. It is only used with
2113 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
2117 <term><varname>AllowPortToBeRoot=
</varname></term>
2119 <para>Takes a boolean. Configures whether a given port is allowed to
2120 become a root port. Only used when STP is enabled on the bridge.
2121 When unset, the kernel's default will be used.
</para>
2125 <term><varname>ProxyARP=
</varname></term>
2127 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2128 When unset, the kernel's default will be used.
</para>
2132 <term><varname>ProxyARPWiFi=
</varname></term>
2134 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2135 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
2136 When unset, the kernel's default will be used.
</para>
2140 <term><varname>MulticastRouter=
</varname></term>
2142 <para>Configures this port for having multicast routers attached. A port with a multicast
2143 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
2144 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
2145 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
2146 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
2147 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
2151 <term><varname>Cost=
</varname></term>
2153 <para>Sets the
"cost" of sending packets of this interface.
2154 Each port in a bridge may have a different speed and the cost
2155 is used to decide which link to use. Faster interfaces
2156 should have lower costs. It is an integer value between
1 and
2161 <term><varname>Priority=
</varname></term>
2163 <para>Sets the
"priority" of sending packets on this interface.
2164 Each port in a bridge may have a different priority which is used
2165 to decide which link to use. Lower value means higher priority.
2166 It is an integer value between
0 to
63. Networkd does not set any
2167 default, meaning the kernel default value of
32 is used.
</para>
2173 <title>[BridgeFDB] Section Options
</title>
2174 <para>The
<literal>[BridgeFDB]
</literal> section manages the
2175 forwarding database table of a port and accepts the following
2176 keys. Specify several
<literal>[BridgeFDB]
</literal> sections to
2177 configure several static MAC table entries.
</para>
2179 <variablelist class='network-directives'
>
2181 <term><varname>MACAddress=
</varname></term>
2183 <para>As in the
<literal>[Network]
</literal> section. This
2184 key is mandatory.
</para>
2188 <term><varname>Destination=
</varname></term>
2190 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
2194 <term><varname>VLANId=
</varname></term>
2196 <para>The VLAN ID for the new static MAC table entry. If
2197 omitted, no VLAN ID information is appended to the new static MAC
2202 <term><varname>VNI=
</varname></term>
2204 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2205 the remote VXLAN tunnel endpoint. Takes a number in the range
1-
16777215.
2206 Defaults to unset.
</para>
2210 <term><varname>AssociatedWith=
</varname></term>
2212 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
2213 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
2214 <literal>use
</literal> means the address is in use. User space can use this option to
2215 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
2216 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
2217 means the address is associated with master devices fdb.
<literal>router
</literal> means
2218 the destination address is associated with a router. Note that it's valid if the referenced
2219 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
2226 <title>[CAN] Section Options
</title>
2227 <para>The
<literal>[CAN]
</literal> section manages the Controller Area Network (CAN bus) and accepts the
2228 following keys.
</para>
2229 <variablelist class='network-directives'
>
2231 <term><varname>BitRate=
</varname></term>
2233 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
2234 be used here.
</para>
2238 <term><varname>SamplePoint=
</varname></term>
2240 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2241 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2245 <term><varname>RestartSec=
</varname></term>
2247 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2248 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2249 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2250 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2251 automatic restart off. By default automatic restart is disabled.
</para>
2255 <term><varname>TripleSampling=
</varname></term>
2257 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2258 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
2265 <title>[TrafficControlQueueingDiscipline] Section Options
</title>
2266 <para>The
<literal>[TrafficControlQueueingDiscipline]
</literal> section manages the Traffic control. It can be used
2267 to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP applications,
2268 or limit the bandwidth usage of a particular service to simulate internet connections.
</para>
2270 <variablelist class='network-directives'
>
2272 <term><varname>Parent=
</varname></term>
2274 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2275 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2280 <term><varname>NetworkEmulatorDelaySec=
</varname></term>
2282 <para>Specifies the fixed amount of delay to be added to all packets going out of the
2283 interface. Defaults to unset.
</para>
2288 <term><varname>NetworkEmulatorDelayJitterSec=
</varname></term>
2290 <para>Specifies the chosen delay to be added to the packets outgoing to the network
2291 interface. Defaults to unset.
</para>
2296 <term><varname>NetworkEmulatorPacketLimit=
</varname></term>
2298 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
2299 An unsigned integer ranges
0 to
4294967294. Defaults to
1000.
</para>
2304 <term><varname>NetworkEmulatorLossRate=
</varname></term>
2306 <para>Specifies an independent loss probability to be added to the packets outgoing from the
2307 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2312 <term><varname>NetworkEmulatorDuplicateRate=
</varname></term>
2314 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
2315 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2320 <term><varname>TokenBufferFilterLatencySec=
</varname></term>
2322 <para>Specifies the latency parameter, which specifies the maximum amount of time a
2323 packet can sit in the Token Buffer Filter (TBF). Defaults to unset.
</para>
2328 <term><varname>TokenBufferFilterLimitSize=
</varname></term>
2330 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
2331 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
2332 respectively, to the base of
1000. Defaults to unset.
</para>
2337 <term><varname>TokenBufferFilterBurst=
</varname></term>
2339 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
2340 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
2341 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to
2347 <term><varname>TokenBufferFilterRate=
</varname></term>
2349 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
2350 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
2351 Defaults to unset.
</para>
2356 <term><varname>TokenBufferFilterMPUBytes=
</varname></term>
2358 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
2359 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2360 Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to zero.
</para>
2365 <term><varname>TokenBufferFilterPeakRate=
</varname></term>
2367 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
2368 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2369 1000. Defaults to unset.
</para>
2374 <term><varname>TokenBufferFilterMTUBytes=
</varname></term>
2376 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
2377 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000.
2378 Defaults to unset.
</para>
2383 <term><varname>StochasticFairnessQueueingPerturbPeriodSec=
</varname></term>
2385 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
2390 <term><varname>ControlledDelayPacketLimit=
</varname></term>
2392 <para>Specifies the hard lmit on the queue size in number of packets. When this limit is reached, incoming packets are
2393 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2398 <term><varname>ControlledDelayTargetSec=
</varname></term>
2400 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2401 Defaults to unset and kernel's default is used.
</para>
2406 <term><varname>ControlledDelayIntervalSec=
</varname></term>
2408 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2409 become too stale. Defaults to unset and kernel's default is used.
</para>
2414 <term><varname>ControlledDelayECN=
</varname></term>
2416 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2417 unset and kernel's default is used.
</para>
2422 <term><varname>ControlledDelayCEThresholdSec=
</varname></term>
2424 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2425 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2430 <term><varname>FairQueuingControlledDelayPacketLimit=
</varname></term>
2432 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2433 dropped. Defaults to unset and kernel's default is used.
</para>
2438 <term><varname>FairQueuingControlledDelayMemoryLimit=
</varname></term>
2440 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
2441 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2442 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2447 <term><varname>FairQueuingControlledDelayFlows=
</varname></term>
2449 <para>Specifies the number of flows into which the incoming packets are classified.
2450 Defaults to unset and kernel's default is used.
</para>
2455 <term><varname>FairQueuingControlledDelayTargetSec=
</varname></term>
2457 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2458 Defaults to unset and kernel's default is used.
</para>
2463 <term><varname>FairQueuingControlledDelayIntervalSec=
</varname></term>
2465 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2466 become too stale. Defaults to unset and kernel's default is used.
</para>
2471 <term><varname>FairQueuingControlledDelayQuantum=
</varname></term>
2473 <para>Specifies the number of bytes used as 'deficit' in the fair queuing algorithmtimespan.
2474 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2475 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2480 <term><varname>FairQueuingControlledDelayECN=
</varname></term>
2482 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2483 unset and kernel's default is used.
</para>
2488 <term><varname>FairQueuingControlledDelayCEThresholdSec=
</varname></term>
2490 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2491 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2496 <term><varname>FairQueueTrafficPolicingPacketLimit=
</varname></term>
2498 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2499 dropped. Defaults to unset and kernel's default is used.
</para>
2504 <term><varname>FairQueueTrafficPolicingFlowLimit=
</varname></term>
2506 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
2507 unset and kernel's default is used.
</para>
2512 <term><varname>FairQueueTrafficPolicingQuantum=
</varname></term>
2514 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
2515 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2516 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
2517 default is used.
</para>
2522 <term><varname>FairQueueTrafficPolicingInitialQuantum=
</varname></term>
2524 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
2525 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
2526 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
2527 kernel's default is used.
</para>
2532 <term><varname>FairQueueTrafficPolicingMaximumRate=
</varname></term>
2534 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
2535 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2536 1000. Defaults to unset and kernel's default is used.
</para>
2541 <term><varname>FairQueueTrafficPolicingBuckets=
</varname></term>
2543 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
2544 kernel's default is used.
</para>
2549 <term><varname>FairQueueTrafficPolicingOrphanMask=
</varname></term>
2551 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
2552 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
2553 kernel's default is used.
</para>
2558 <term><varname>FairQueueTrafficPolicingPacing=
</varname></term>
2560 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
2561 default is used.
</para>
2566 <term><varname>FairQueueTrafficPolicingCEThresholdSec=
</varname></term>
2568 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2569 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2577 <title>[BridgeVLAN] Section Options
</title>
2578 <para>The
<literal>[BridgeVLAN]
</literal> section manages the VLAN ID configuration of a bridge port and accepts
2579 the following keys. Specify several
<literal>[BridgeVLAN]
</literal> sections to configure several VLAN entries.
2580 The
<varname>VLANFiltering=
</varname> option has to be enabled, see
<literal>[Bridge]
</literal> section in
2581 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2583 <variablelist class='network-directives'
>
2585 <term><varname>VLAN=
</varname></term>
2587 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
2588 from
1 to
4094.
</para>
2592 <term><varname>EgressUntagged=
</varname></term>
2594 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
2595 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
2596 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
2600 <term><varname>PVID=
</varname></term>
2602 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
2603 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
2604 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
2611 <title>Examples
</title>
2613 <title>Static network configuration
</title>
2615 <programlisting># /etc/systemd/network/
50-static.network
2620 Address=
192.168.0.15/
24
2621 Gateway=
192.168.0.1</programlisting>
2623 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
2624 specified gateway will be used for a default route.
</para>
2628 <title>DHCP on ethernet links
</title>
2630 <programlisting># /etc/systemd/network/
80-dhcp.network
2635 DHCP=yes
</programlisting>
2637 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
2638 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
2642 <title>IPv6 Prefix Delegation
</title>
2644 <programlisting># /etc/systemd/network/
55-ipv6-pd-upstream.network
2649 DHCP=ipv6
</programlisting>
2651 <programlisting># /etc/systemd/network/
56-ipv6-pd-downstream.network
2656 IPv6PrefixDelegation=dhcpv6
</programlisting>
2658 <para>This will enable IPv6 PD on the interface enp1s0 as an upstream interface where the
2659 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
</para>
2663 <title>A bridge with two enslaved links
</title>
2665 <programlisting># /etc/systemd/network/
25-bridge-static.network
2670 Address=
192.168.0.15/
24
2672 DNS=
192.168.0.1</programlisting>
2674 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
2679 Bridge=bridge0
</programlisting>
2681 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
2686 Bridge=bridge0
</programlisting>
2688 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
2689 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
2690 and network assigned, and a default route via the specified gateway will be
2691 added. The specified DNS server will be added to the global list of DNS resolvers.
2699 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
2715 EgressUntagged=
300-
400</programlisting>
2717 <para>This overrides the configuration specified in the previous example for the
2718 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
2719 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
2720 untagged when they leave on this interface. Untagged packets which arrive on this
2721 interface will be assigned VLAN ID
42.
</para>
2725 <title>Various tunnels
</title>
2727 <programlisting>/etc/systemd/network/
25-tunnels.network
2738 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
2744 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
2750 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
2756 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
2762 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
2763 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
2767 <title>A bond device
</title>
2769 <programlisting># /etc/systemd/network/
30-bond1.network
2777 <programlisting># /etc/systemd/network/
30-bond1.netdev
2783 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
2785 MACAddress=
52:
54:
00:e9:
64:
41
2791 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
2793 MACAddress=
52:
54:
00:e9:
64:
42
2799 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
2800 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
2801 will be used to acquire an address.
</para>
2805 <title>Virtual Routing and Forwarding (VRF)
</title>
2806 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
2807 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
2808 within the routing table defined during VRF creation. For kernels before
4.8 traffic
2809 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
2811 <programlisting># /etc/systemd/network/
25-vrf.network
2821 <title>MacVTap
</title>
2822 <para>This brings up a network interface
<literal>macvtap-test
</literal>
2823 and attaches it to
<literal>enp0s25
</literal>.
</para>
2824 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
2829 MACVTAP=macvtap-test
2834 <title>A Xfrm interface with physical underlying device.
</title>
2836 <programlisting># /etc/systemd/network/
27-xfrm.netdev
2841 InterfaceId=
7</programlisting>
2843 <programlisting># /etc/systemd/network/
27-eth0.network
2848 Xfrm=xfrm0
</programlisting>
2850 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
2851 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
2852 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
2858 <title>See Also
</title>
2860 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
2861 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
2862 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2863 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
2864 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>