man/systemd.network.xml

   1 <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   This file is part of systemd.
   7
   8   Copyright 2013 Tom Gundersen
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 -->
  23
  24 <refentry id="systemd.network" conditional='ENABLE_NETWORKD'>
  25
  26   <refentryinfo>
  27     <title>systemd.network</title>
  28     <productname>systemd</productname>
  29
  30     <authorgroup>
  31       <author>
  32         <contrib>Developer</contrib>
  33         <firstname>Tom</firstname>
  34         <surname>Gundersen</surname>
  35         <email>teg@jklm.no</email>
  36       </author>
  37     </authorgroup>
  38   </refentryinfo>
  39
  40   <refmeta>
  41     <refentrytitle>systemd.network</refentrytitle>
  42     <manvolnum>5</manvolnum>
  43   </refmeta>
  44
  45   <refnamediv>
  46     <refname>systemd.network</refname>
  47     <refpurpose>Network configuration</refpurpose>
  48   </refnamediv>
  49
  50   <refsynopsisdiv>
  51     <para><filename><replaceable>network</replaceable>.network</filename></para>
  52   </refsynopsisdiv>
  53
  54   <refsect1>
  55     <title>Description</title>
  56
  57     <para>Network setup is performed by
  58     <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
  59     </para>
  60
  61     <para>Network files must have the extension
  62     <filename>.network</filename>; other extensions are ignored.
  63     Networks are applied to links whenever the links appear.</para>
  64
  65     <para>The <filename>.network</filename> files are read from the
  66     files located in the system network directory
  67     <filename>/usr/lib/systemd/network</filename>, the volatile
  68     runtime network directory
  69     <filename>/run/systemd/network</filename> and the local
  70     administration network directory
  71     <filename>/etc/systemd/network</filename>. All configuration files
  72     are collectively sorted and processed in lexical order, regardless
  73     of the directories in which they live. However, files with
  74     identical filenames replace each other. Files in
  75     <filename>/etc</filename> have the highest priority, files in
  76     <filename>/run</filename> take precedence over files with the same
  77     name in <filename>/usr/lib</filename>. This can be used to
  78     override a system-supplied configuration file with a local file if
  79     needed. As a special case, an empty file (file size 0) or symlink
  80     with the same name pointing to <filename>/dev/null</filename>
  81     disables the configuration file entirely (it is "masked").</para>
  82
  83     <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6 nor IPv6LL enabled,
  84     shall be considered to have no IPv6 support. IPv6 will be automatically disabled for that interface by writing "1"
  85     to <filename>/proc/sys/net/ipv6/conf/<replaceable>ifname</replaceable>/disable_ipv6</filename>.
  86     </para>
  87   </refsect1>
  88
  89   <refsect1>
  90     <title>[Match] Section Options</title>
  91
  92       <para>The network file contains a <literal>[Match]</literal>
  93       section, which determines if a given network file may be applied
  94       to a given device; and a <literal>[Network]</literal> section
  95       specifying how the device should be configured. The first (in
  96       lexical order) of the network files that matches a given device
  97       is applied, all later files are ignored, even if they match as
  98       well.</para>
  99
 100       <para>A network file is said to match a device if each of the
 101       entries in the <literal>[Match]</literal> section matches, or if
 102       the section is empty. The following keys are accepted:</para>
 103
 104       <variablelist class='network-directives'>
 105         <varlistentry>
 106           <term><varname>MACAddress=</varname></term>
 107           <listitem>
 108             <para>The hardware address.</para>
 109           </listitem>
 110         </varlistentry>
 111         <varlistentry>
 112           <term><varname>Path=</varname></term>
 113           <listitem>
 114             <para>A whitespace-separated list of shell-style globs
 115             matching the persistent path, as exposed by the udev
 116             property <literal>ID_PATH</literal>.</para>
 117           </listitem>
 118         </varlistentry>
 119         <varlistentry>
 120           <term><varname>Driver=</varname></term>
 121           <listitem>
 122             <para>A whitespace-separated list of shell-style globs
 123             matching the driver currently bound to the device, as
 124             exposed by the udev property <literal>DRIVER</literal>
 125             of its parent device, or if that is not set the driver
 126             as exposed by <literal>ethtool -i</literal> of the
 127             device itself.</para>
 128           </listitem>
 129         </varlistentry>
 130         <varlistentry>
 131           <term><varname>Type=</varname></term>
 132           <listitem>
 133             <para>A whitespace-separated list of shell-style globs
 134             matching the device type, as exposed by the udev property
 135             <literal>DEVTYPE</literal>.</para>
 136           </listitem>
 137         </varlistentry>
 138         <varlistentry>
 139           <term><varname>Name=</varname></term>
 140           <listitem>
 141             <para>A whitespace-separated list of shell-style globs
 142             matching the device name, as exposed by the udev property
 143             <literal>INTERFACE</literal>.</para>
 144           </listitem>
 145         </varlistentry>
 146         <varlistentry>
 147           <term><varname>Host=</varname></term>
 148           <listitem>
 149             <para>Matches against the hostname or machine ID of the
 150             host. See <literal>ConditionHost=</literal> in
 151             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 152             for details.
 153             </para>
 154           </listitem>
 155         </varlistentry>
 156         <varlistentry>
 157           <term><varname>Virtualization=</varname></term>
 158           <listitem>
 159             <para>Checks whether the system is executed in a virtualized
 160             environment and optionally test whether it is a specific
 161             implementation. See <literal>ConditionVirtualization=</literal> in
 162             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 163             for details.
 164             </para>
 165           </listitem>
 166         </varlistentry>
 167         <varlistentry>
 168           <term><varname>KernelCommandLine=</varname></term>
 169           <listitem>
 170             <para>Checks whether a specific kernel command line option is
 171             set (or if prefixed with the exclamation mark unset). See
 172             <literal>ConditionKernelCommandLine=</literal> in
 173             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 174             for details.
 175             </para>
 176           </listitem>
 177         </varlistentry>
 178         <varlistentry>
 179           <term><varname>Architecture=</varname></term>
 180           <listitem>
 181             <para>Checks whether the system is running on a specific
 182             architecture. See <literal>ConditionArchitecture=</literal> in
 183             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 184             for details.
 185             </para>
 186           </listitem>
 187         </varlistentry>
 188       </variablelist>
 189
 190   </refsect1>
 191
 192   <refsect1>
 193     <title>[Link] Section Options</title>
 194
 195     <para> The <literal>[Link]</literal> section accepts the following keys:</para>
 196
 197     <variablelist class='network-directives'>
 198       <varlistentry>
 199         <term><varname>MACAddress=</varname></term>
 200         <listitem>
 201           <para>The hardware address.</para>
 202         </listitem>
 203       </varlistentry>
 204       <varlistentry>
 205         <term><varname>MTUBytes=</varname></term>
 206         <listitem>
 207           <para>The maximum transmission unit in bytes to set for the
 208           device. The usual suffixes K, M, G, are supported and are
 209           understood to the base of 1024.</para>
 210           <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
 211           below 1280 (the minimum MTU for IPv6) it will automatically be increased to this value.</para>
 212         </listitem>
 213       </varlistentry>
 214     </variablelist>
 215   </refsect1>
 216
 217   <refsect1>
 218     <title>[Network] Section Options</title>
 219
 220       <para>The <literal>[Network]</literal> section accepts the following keys:</para>
 221
 222       <variablelist class='network-directives'>
 223         <varlistentry>
 224           <term><varname>Description=</varname></term>
 225           <listitem>
 226             <para>A description of the device. This is only used for
 227             presentation purposes.</para>
 228           </listitem>
 229         </varlistentry>
 230         <varlistentry>
 231           <term><varname>DHCP=</varname></term>
 232           <listitem>
 233             <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
 234             <literal>yes</literal>, <literal>no</literal>,
 235             <literal>ipv4</literal>, or <literal>ipv6</literal>.</para>
 236
 237             <para>Note that DHCPv6 will by default be triggered by Router
 238             Advertisement, if that is enabled, regardless of this parameter.
 239             By enabling DHCPv6 support explicitly, the DHCPv6 client will
 240             be started regardless of the presence of routers on the link,
 241             or what flags the routers pass. See
 242             <literal>IPv6AcceptRouterAdvertisements=</literal>.</para>
 243
 244             <para>Furthermore, note that by default the domain name
 245             specified through DHCP is not used for name resolution.
 246             See option <option>UseDomains=</option> below.</para>
 247
 248             <para>See the <literal>[DHCP]</literal> section below for further configuration options for the DHCP client
 249             support.</para>
 250           </listitem>
 251         </varlistentry>
 252         <varlistentry>
 253           <term><varname>DHCPServer=</varname></term>
 254           <listitem>
 255             <para>A boolean. Enables DHCPv4 server support. Defaults
 256             to <literal>no</literal>. Further settings for the DHCP
 257             server may be set in the <literal>[DHCPServer]</literal>
 258             section described below.</para>
 259           </listitem>
 260         </varlistentry>
 261         <varlistentry>
 262           <term><varname>LinkLocalAddressing=</varname></term>
 263           <listitem>
 264             <para>Enables link-local address autoconfiguration. Accepts
 265             <literal>yes</literal>, <literal>no</literal>,
 266             <literal>ipv4</literal>, or <literal>ipv6</literal>. Defaults to
 267             <literal>ipv6</literal>.</para>
 268           </listitem>
 269         </varlistentry>
 270         <varlistentry>
 271           <term><varname>IPv4LLRoute=</varname></term>
 272           <listitem>
 273             <para>A boolean. When true, sets up the route needed for
 274             non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
 275             to false.
 276             </para>
 277           </listitem>
 278         </varlistentry>
 279         <varlistentry>
 280           <term><varname>IPv6Token=</varname></term>
 281           <listitem>
 282             <para>An IPv6 address with the top 64 bits unset. When set, indicates the
 283             64-bit interface part of SLAAC IPv6 addresses for this link. Note that
 284             the token is only ever used for SLAAC, and not for DHCPv6 addresses, even
 285             in the case DHCP is requested by router advertisement. By default, the
 286             token is autogenerated.</para>
 287           </listitem>
 288         </varlistentry>
 289         <varlistentry>
 290           <term><varname>LLMNR=</varname></term>
 291           <listitem>
 292             <para>A boolean or <literal>resolve</literal>. When true,
 293             enables <ulink
 294             url="https://tools.ietf.org/html/rfc4795">Link-Local
 295             Multicast Name Resolution</ulink> on the link. When set to
 296             <literal>resolve</literal>, only resolution is enabled,
 297             but not host registration and announcement. Defaults to
 298             true. This setting is read by
 299             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 300           </listitem>
 301         </varlistentry>
 302         <varlistentry>
 303           <term><varname>MulticastDNS=</varname></term>
 304           <listitem>
 305             <para>A boolean or <literal>resolve</literal>. When true,
 306             enables <ulink
 307             url="https://tools.ietf.org/html/rfc6762">Multicast
 308             DNS</ulink> support on the link. When set to
 309             <literal>resolve</literal>, only resolution is enabled,
 310             but not host or service registration and
 311             announcement. Defaults to false. This setting is read by
 312             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 313           </listitem>
 314         </varlistentry>
 315         <varlistentry>
 316           <term><varname>DNSSEC=</varname></term>
 317           <listitem>
 318             <para>A boolean or
 319             <literal>allow-downgrade</literal>. When true, enables
 320             <ulink
 321             url="https://tools.ietf.org/html/rfc4033">DNSSEC</ulink>
 322             DNS validation support on the link. When set to
 323             <literal>allow-downgrade</literal>, compatibility with
 324             non-DNSSEC capable networks is increased, by automatically
 325             turning off DNSEC in this case. This option defines a
 326             per-interface setting for
 327             <citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
 328             global <varname>DNSSEC=</varname> option. Defaults to
 329             false. This setting is read by
 330             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 331           </listitem>
 332         </varlistentry>
 333         <varlistentry>
 334           <term><varname>DNSSECNegativeTrustAnchors=</varname></term>
 335           <listitem><para>A space-separated list of DNSSEC negative
 336           trust anchor domains. If specified and DNSSEC is enabled,
 337           look-ups done via the interface's DNS server will be subject
 338           to the list of negative trust anchors, and not require
 339           authentication for the specified domains, or anything below
 340           it. Use this to disable DNSSEC authentication for specific
 341           private domains, that cannot be proven valid using the
 342           Internet DNS hierarchy. Defaults to the empty list. This
 343           setting is read by
 344           <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 345           </listitem>
 346         </varlistentry>
 347         <varlistentry>
 348           <term><varname>LLDP=</varname></term>
 349           <listitem>
 350             <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
 351             implemented on professional routers and bridges which announces which physical port a system is connected
 352             to, as well as other related data. Accepts a boolean or the special value
 353             <literal>routers-only</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
 354             neighbors maintained. If <literal>routers-only</literal> is set only LLDP data of various types of routers
 355             is collected and LLDP data about other types of devices ignored (such as stations, telephones and
 356             others). If false, LLDP reception is disabled. Defaults to <literal>routers-only</literal>. Use
 357             <citerefentry><refentrytitle>networkctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
 358             collected neighbor data. LLDP is only available on Ethernet links. See <varname>EmitLLDP=</varname> below
 359             for enabling LLDP packet emission from the local system.
 360             </para>
 361           </listitem>
 362         </varlistentry>
 363         <varlistentry>
 364           <term><varname>EmitLLDP=</varname></term>
 365           <listitem>
 366             <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
 367             <literal>nearest-bridge</literal>, <literal>non-tpmr-bridge</literal> and
 368             <literal>customer-bridge</literal>.  Defaults to false, which turns off LLDP packet emission. If not false,
 369             a short LLDP packet with information about the local system is sent out in regular intervals on the
 370             link. The LLDP packet will contain information about the local host name, the local machine ID (as stored
 371             in <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
 372             local interface name, as well as the pretty hostname of the system (as set in
 373             <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
 374             emission is only available on Ethernet links. Note that this setting passes data suitable for
 375             identification of host to the network and should thus not be enabled on untrusted networks, where such
 376             identification data should not be made available. Use this option to permit other systems to identify on
 377             which interfaces they are connected to this system. The three special values control propagation of the
 378             LLDP packets. The <literal>nearest-bridge</literal> setting permits propagation only to the nearest
 379             connected bridge, <literal>non-tpmr-bridge</literal> permits propagation across Two-Port MAC Relays, but
 380             not any other bridges, and <literal>customer-bridge</literal> permits propagation until a customer bridge
 381             is reached. For details about these concepts, see <ulink
 382             url="http://standards.ieee.org/getieee802/download/802.1AB-2009.pdf">IEEE 802.1AB-2009</ulink>. Note that
 383             configuring this setting to true is equivalent to <literal>nearest-bridge</literal>, the recommended and
 384             most restricted level of propagation. See <varname>LLDP=</varname> above for an option to enable LLDP
 385             reception.</para>
 386           </listitem>
 387         </varlistentry>
 388         <varlistentry>
 389           <term><varname>BindCarrier=</varname></term>
 390           <listitem>
 391             <para>A link name or a list of link names. When set, controls the behavior of the current
 392             link. When all links in the list are in an operational down state, the current link is brought
 393             down. When at least one link has carrier, the current interface is brought up.
 394             </para>
 395           </listitem>
 396         </varlistentry>
 397         <varlistentry>
 398           <term><varname>Address=</varname></term>
 399           <listitem>
 400             <para>A static IPv4 or IPv6 address and its prefix length,
 401             separated by a <literal>/</literal> character. Specify
 402             this key more than once to configure several addresses.
 403             The format of the address must be as described in
 404             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 405             This is a short-hand for an [Address] section only
 406             containing an Address key (see below). This option may be
 407             specified more than once.
 408             </para>
 409
 410             <para>If the specified address is 0.0.0.0 (for IPv4) or
 411             [::] (for IPv6), a new address range of the requested size
 412             is automatically allocated from a system-wide pool of
 413             unused ranges. The allocated range is checked against all
 414             current network interfaces and all known network
 415             configuration files to avoid address range conflicts. The
 416             default system-wide pool consists of 192.168.0.0/16,
 417             172.16.0.0/12 and 10.0.0.0/8 for IPv4, and fc00::/7 for
 418             IPv6. This functionality is useful to manage a large
 419             number of dynamically created network interfaces with the
 420             same network configuration and automatic address range
 421             assignment.</para>
 422
 423           </listitem>
 424         </varlistentry>
 425         <varlistentry>
 426           <term><varname>Gateway=</varname></term>
 427           <listitem>
 428             <para>The gateway address, which must be in the format
 429             described in
 430             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 431             This is a short-hand for a [Route] section only containing
 432             a Gateway key. This option may be specified more than
 433             once.</para>
 434           </listitem>
 435         </varlistentry>
 436         <varlistentry>
 437           <term><varname>DNS=</varname></term>
 438           <listitem>
 439             <para>A DNS server address, which must be in the format
 440             described in
 441             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 442             This option may be specified more than once. This setting is read by
 443             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 444           </listitem>
 445         </varlistentry>
 446         <varlistentry>
 447           <term><varname>Domains=</varname></term>
 448           <listitem>
 449             <para>The domains used for DNS host name resolution on this link. Takes a list of DNS domain names which
 450             are used as search suffixes for extending single-label host names (host names containing no dots) to become
 451             fully qualified domain names (FQDNs). If a single-label host name is resolved on this interface, each of
 452             the specified search domains are appended to it in turn, converting it into a fully qualified domain name,
 453             until one of them may be successfully resolved.</para>
 454
 455             <para>The specified domains are also used for routing of DNS queries: look-ups for host names ending in the
 456             domains specified here are preferably routed to the DNS servers configured for this interface. If a domain
 457             name is prefixed with <literal>~</literal>, the domain name becomes a pure "routing" domain, is used for
 458             DNS query routing purposes only and is not used in the described domain search logic. By specifying a
 459             routing domain of <literal>~.</literal> (the tilde indicating definition of a routing domain, the dot
 460             referring to the DNS root domain which is the implied suffix of all valid DNS names) it is possible to
 461             route all DNS traffic preferably to the DNS server specified for this interface. The route domain logic is
 462             particularly useful on multi-homed hosts with DNS servers serving particular private DNS zones on each
 463             interface.</para>
 464
 465             <para>This setting is read by
 466             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 467           </listitem>
 468         </varlistentry>
 469         <varlistentry>
 470           <term><varname>NTP=</varname></term>
 471           <listitem>
 472             <para>An NTP server address. This option may be specified more than once. This setting is read by
 473             <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 474           </listitem>
 475         </varlistentry>
 476         <varlistentry>
 477           <term><varname>IPForward=</varname></term>
 478           <listitem><para>Configures IP packet forwarding for the
 479           system. If enabled, incoming packets on any network
 480           interface will be forwarded to any other interfaces
 481           according to the routing table. Takes either a boolean
 482           argument, or the values <literal>ipv4</literal> or
 483           <literal>ipv6</literal>, which only enable IP packet
 484           forwarding for the specified address family.  This controls
 485           the <filename>net.ipv4.ip_forward</filename> and
 486           <filename>net.ipv6.conf.all.forwarding</filename> sysctl
 487           options of the network interface (see <ulink
 488           url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink>
 489           for details about sysctl options). Defaults to
 490           <literal>no</literal>.</para>
 491
 492           <para>Note: this setting controls a global kernel option,
 493           and does so one way only: if a network that has this setting
 494           enabled is set up the global setting is turned on.  However,
 495           it is never turned off again, even after all networks with
 496           this setting enabled are shut down again.</para>
 497
 498           <para>To allow IP packet forwarding only between specific
 499           network interfaces use a firewall.</para>
 500           </listitem>
 501         </varlistentry>
 502         <varlistentry>
 503           <term><varname>IPMasquerade=</varname></term>
 504           <listitem><para>Configures IP masquerading for the network
 505           interface. If enabled, packets forwarded from the network
 506           interface will be appear as coming from the local host.
 507           Takes a boolean argument. Implies
 508           <varname>IPForward=ipv4</varname>. Defaults to
 509           <literal>no</literal>.</para></listitem>
 510         </varlistentry>
 511         <varlistentry>
 512           <term><varname>IPv6PrivacyExtensions=</varname></term>
 513           <listitem><para>Configures use of stateless temporary
 514           addresses that change over time (see <ulink
 515           url="https://tools.ietf.org/html/rfc4941">RFC 4941</ulink>,
 516           Privacy Extensions for Stateless Address Autoconfiguration
 517           in IPv6). Takes a boolean or the special values
 518           <literal>prefer-public</literal> and
 519           <literal>kernel</literal>. When true, enables the privacy
 520           extensions and prefers temporary addresses over public
 521           addresses. When <literal>prefer-public</literal>, enables the
 522           privacy extensions, but prefers public addresses over
 523           temporary addresses. When false, the privacy extensions
 524           remain disabled. When <literal>kernel</literal>, the kernel's
 525           default setting will be left in place.  Defaults to
 526           <literal>no</literal>.</para></listitem>
 527         </varlistentry>
 528         <varlistentry>
 529           <term><varname>IPv6AcceptRouterAdvertisements=</varname></term>
 530           <listitem><para>Force the setting of the <filename>accept_ra</filename>
 531           (router advertisements) setting for the interface.
 532           When unset, the kernel default is used, and router
 533           advertisements are accepted only when local forwarding
 534           is disabled for that interface.
 535           When router advertisements are accepted, they will
 536           trigger the start of the DHCPv6 client if the relevant
 537           flags are passed, or if no routers are found on the link.
 538           Takes a boolean. If true, router advertisements are
 539           accepted, when false, router advertisements are ignored,
 540           independently of the local forwarding state.</para>
 541
 542           <para>See
 543           <ulink url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink>
 544           in the kernel documentation, but note that systemd's
 545           setting of <constant>1</constant> corresponds to
 546           kernel's setting of <constant>2</constant>.</para>
 547         </listitem>
 548         </varlistentry>
 549         <varlistentry>
 550           <term><varname>IPv6DuplicateAddressDetection=</varname></term>
 551           <listitem><para>Configures the amount of IPv6 Duplicate
 552           Address Detection (DAD) probes to send. Defaults to unset.
 553         </para></listitem>
 554         </varlistentry>
 555         <varlistentry>
 556           <term><varname>IPv6HopLimit=</varname></term>
 557           <listitem><para>Configures IPv6 Hop Limit. For each router that
 558           forwards the packet, the hop limit is decremented by 1. When the
 559           hop limit field reaches zero, the packet is discarded.
 560           Defaults to unset.
 561         </para></listitem>
 562         </varlistentry>
 563         <varlistentry>
 564           <term><varname>ProxyARP=</varname></term>
 565           <listitem><para>A boolean. Configures proxy ARP. Proxy ARP is the technique in which one host,
 566           usually a router, answers ARP requests intended for another machine. By "faking" its identity,
 567           the router accepts responsibility for routing packets to the "real" destination. (see <ulink
 568           url="https://tools.ietf.org/html/rfc1027">RFC 1027</ulink>.
 569           Defaults to unset.
 570         </para></listitem>
 571         </varlistentry>
 572         <varlistentry>
 573           <term><varname>Bridge=</varname></term>
 574           <listitem>
 575             <para>The name of the bridge to add the link to.</para>
 576           </listitem>
 577         </varlistentry>
 578         <varlistentry>
 579           <term><varname>Bond=</varname></term>
 580           <listitem>
 581             <para>The name of the bond to add the link to.</para>
 582           </listitem>
 583         </varlistentry>
 584         <varlistentry>
 585           <term><varname>VLAN=</varname></term>
 586           <listitem>
 587             <para>The name of a VLAN to create on the link. This
 588             option may be specified more than once.</para>
 589           </listitem>
 590         </varlistentry>
 591         <varlistentry>
 592           <term><varname>MACVLAN=</varname></term>
 593           <listitem>
 594             <para>The name of a MACVLAN to create on the link. This
 595             option may be specified more than once.</para>
 596           </listitem>
 597         </varlistentry>
 598         <varlistentry>
 599           <term><varname>VXLAN=</varname></term>
 600           <listitem>
 601             <para>The name of a VXLAN to create on the link. This
 602             option may be specified more than once.</para>
 603           </listitem>
 604         </varlistentry>
 605         <varlistentry>
 606           <term><varname>Tunnel=</varname></term>
 607           <listitem>
 608             <para>The name of a Tunnel to create on the link. This
 609             option may be specified more than once.</para>
 610           </listitem>
 611         </varlistentry>
 612       </variablelist>
 613
 614   </refsect1>
 615
 616   <refsect1>
 617     <title>[Address] Section Options</title>
 618
 619       <para>An <literal>[Address]</literal> section accepts the
 620       following keys. Specify several <literal>[Address]</literal>
 621       sections to configure several addresses.</para>
 622
 623       <variablelist class='network-directives'>
 624         <varlistentry>
 625           <term><varname>Address=</varname></term>
 626           <listitem>
 627             <para>As in the <literal>[Network]</literal> section. This
 628             key is mandatory.</para>
 629           </listitem>
 630         </varlistentry>
 631         <varlistentry>
 632           <term><varname>Peer=</varname></term>
 633           <listitem>
 634             <para>The peer address in a point-to-point connection.
 635             Accepts the same format as the <literal>Address</literal>
 636             key.</para>
 637           </listitem>
 638         </varlistentry>
 639         <varlistentry>
 640           <term><varname>Broadcast=</varname></term>
 641           <listitem>
 642             <para>The broadcast address, which must be in the format
 643             described in
 644             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 645             This key only applies to IPv4 addresses. If it is not
 646             given, it is derived from the <literal>Address</literal>
 647             key.</para>
 648           </listitem>
 649         </varlistentry>
 650         <varlistentry>
 651           <term><varname>Label=</varname></term>
 652           <listitem>
 653             <para>An address label.</para>
 654           </listitem>
 655         </varlistentry>
 656         <varlistentry>
 657           <term><varname>PreferredLifetime=</varname></term>
 658           <listitem>
 659             <para>Allows the default "preferred lifetime" of the address to be overridden.
 660             Only three settings are accepted: <literal>forever</literal> or <literal>infinity</literal>
 661             which is the default and means that the address never expires, and <literal>0</literal> which means
 662             that the address is considered immediately "expired" and will not be used,
 663             unless explicitly requested. A setting of PreferredLifetime=0 is useful for
 664             addresses which are added to be used only by a specific application,
 665             which is then configured to use them explicitly.</para>
 666           </listitem>
 667         </varlistentry>
 668       </variablelist>
 669   </refsect1>
 670
 671   <refsect1>
 672     <title>[Route] Section Options</title>
 673       <para>The <literal>[Route]</literal> section accepts the
 674       following keys. Specify several <literal>[Route]</literal>
 675       sections to configure several routes.</para>
 676
 677       <variablelist class='network-directives'>
 678         <varlistentry>
 679           <term><varname>Gateway=</varname></term>
 680           <listitem>
 681             <para>As in the <literal>[Network]</literal> section.</para>
 682           </listitem>
 683         </varlistentry>
 684         <varlistentry>
 685           <term><varname>Destination=</varname></term>
 686           <listitem>
 687             <para>The destination prefix of the route. Possibly
 688             followed by a slash and the prefix length. If omitted, a
 689             full-length host route is assumed.</para>
 690           </listitem>
 691         </varlistentry>
 692         <varlistentry>
 693           <term><varname>Source=</varname></term>
 694           <listitem>
 695             <para>The source prefix of the route. Possibly followed by
 696             a slash and the prefix length. If omitted, a full-length
 697             host route is assumed.</para>
 698           </listitem>
 699         </varlistentry>
 700         <varlistentry>
 701           <term><varname>Metric=</varname></term>
 702           <listitem>
 703             <para>The metric of the route (an unsigned integer).</para>
 704           </listitem>
 705         </varlistentry>
 706         <varlistentry>
 707           <term><varname>Scope=</varname></term>
 708           <listitem>
 709             <para>The scope of the route, which can be <literal>global</literal>,
 710             <literal>link</literal> or <literal>host</literal>. Defaults to
 711             <literal>global</literal>.</para>
 712           </listitem>
 713         </varlistentry>
 714         <varlistentry>
 715           <term><varname>PreferredSource=</varname></term>
 716           <listitem>
 717             <para>The preferred source address of the route. The address
 718             must be in the format described in
 719             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
 720           </listitem>
 721         </varlistentry>
 722         <varlistentry>
 723           <term><varname>Table=<replaceable>num</replaceable></varname></term>
 724           <listitem>
 725           <para>The table identifier for the route (a number between 1 and 4294967295, or 0 to unset).
 726           The table can be retrieved using <command>ip route show table <replaceable>num</replaceable></command>.
 727           </para>
 728           </listitem>
 729         </varlistentry>
 730       </variablelist>
 731   </refsect1>
 732
 733   <refsect1>
 734     <title>[DHCP] Section Options</title>
 735       <para>The <literal>[DHCP]</literal> section configures the
 736       DHCPv4 and DHCP6 client, if it is enabled with the
 737       <varname>DHCP=</varname> setting described above:</para>
 738
 739       <variablelist class='network-directives'>
 740         <varlistentry>
 741           <term><varname>UseDNS=</varname></term>
 742           <listitem>
 743             <para>When true (the default), the DNS servers received
 744             from the DHCP server will be used and take precedence over
 745             any statically configured ones.</para>
 746
 747             <para>This corresponds to the <option>nameserver</option>
 748             option in <citerefentry
 749             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 750           </listitem>
 751         </varlistentry>
 752         <varlistentry>
 753           <term><varname>UseNTP=</varname></term>
 754           <listitem>
 755             <para>When true (the default), the NTP servers received
 756             from the DHCP server will be used by systemd-timesyncd
 757             and take precedence over any statically configured ones.</para>
 758           </listitem>
 759         </varlistentry>
 760         <varlistentry>
 761           <term><varname>UseMTU=</varname></term>
 762           <listitem>
 763             <para>When true, the interface maximum transmission unit
 764             from the DHCP server will be used on the current link.
 765             Defaults to false.</para>
 766           </listitem>
 767         </varlistentry>
 768         <varlistentry>
 769           <term><varname>SendHostname=</varname></term>
 770           <listitem>
 771             <para>When true (the default), the machine's hostname will
 772             be sent to the DHCP server.</para>
 773           </listitem>
 774         </varlistentry>
 775         <varlistentry>
 776           <term><varname>UseHostname=</varname></term>
 777           <listitem>
 778             <para>When true (the default), the hostname received from
 779             the DHCP server will be set as the transient hostname of the system
 780             </para>
 781           </listitem>
 782         </varlistentry>
 783         <varlistentry>
 784         <term><varname>Hostname=</varname></term>
 785         <listitem>
 786           <para>Use this value for the hostname which is sent to the
 787           DHCP server, instead of machine's hostname.</para>
 788         </listitem>
 789       </varlistentry>
 790         <varlistentry>
 791           <term><varname>UseDomains=</varname></term>
 792           <listitem>
 793             <para>Takes a boolean argument, or the special value <literal>route</literal>. When true, the domain name
 794             received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
 795             the <option>Domains=</option> setting. If set to <literal>route</literal>, the domain name received from
 796             the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
 797             the <option>Domains=</option> setting when the argument is prefixed with <literal>~</literal>. Defaults to
 798             false.</para>
 799
 800             <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
 801             of all host names, in particular to single-label names. It is generally safer to use the supplied domain
 802             only as routing domain, rather than as search domain, in order to not have it affect local resolution of
 803             single-label names.</para>
 804
 805             <para>When set to true, this setting corresponds to the <option>domain</option> option in <citerefentry
 806             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 807           </listitem>
 808         </varlistentry>
 809         <varlistentry>
 810           <term><varname>UseRoutes=</varname></term>
 811           <listitem>
 812             <para>When true (the default), the static routes will be
 813             requested from the DHCP server and added to the routing
 814             table with a metric of 1024.</para>
 815           </listitem>
 816         </varlistentry>
 817
 818         <varlistentry>
 819           <term><varname>UseTimezone=</varname></term>
 820
 821           <listitem><para>When true, the timezone received from the
 822           DHCP server will be set as timezone of the local
 823           system. Defaults to <literal>no</literal>.</para></listitem>
 824         </varlistentry>
 825
 826         <varlistentry>
 827           <term><varname>CriticalConnection=</varname></term>
 828           <listitem>
 829             <para>When true, the connection will never be torn down
 830             even if the DHCP lease expires. This is contrary to the
 831             DHCP specification, but may be the best choice if, say,
 832             the root filesystem relies on this connection. Defaults to
 833             false.</para>
 834           </listitem>
 835         </varlistentry>
 836
 837         <varlistentry>
 838           <term><varname>ClientIdentifier=</varname></term>
 839           <listitem>
 840             <para>The DHCPv4 client identifier to use. Either <literal>mac</literal> to use the MAC address of the link
 841             or <literal>duid</literal> (the default, see below) to use a RFC4361-compliant Client ID.</para>
 842           </listitem>
 843         </varlistentry>
 844
 845         <varlistentry>
 846           <term><varname>VendorClassIdentifier=</varname></term>
 847           <listitem>
 848             <para>The vendor class identifier used to identify vendor
 849             type and configuration.</para>
 850           </listitem>
 851         </varlistentry>
 852
 853         <varlistentry>
 854           <term><varname>DUIDType=</varname></term>
 855           <listitem>
 856             <para>Override the global <varname>DUIDType</varname> setting for this network. See
 857             <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 858             for a description of possible values.</para>
 859           </listitem>
 860         </varlistentry>
 861
 862         <varlistentry>
 863           <term><varname>DUIDRawData=</varname></term>
 864           <listitem>
 865             <para>Override the global <varname>DUIDRawData</varname> setting for this network. See
 866             <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 867             for a description of possible values.</para>
 868           </listitem>
 869         </varlistentry>
 870
 871         <varlistentry>
 872           <term><varname>IAID=</varname></term>
 873           <listitem>
 874             <para>The DHCP Identity Association Identifier (IAID) for the interface, a 32-bit unsigned integer.</para>
 875           </listitem>
 876         </varlistentry>
 877
 878         <varlistentry>
 879           <term><varname>RequestBroadcast=</varname></term>
 880           <listitem>
 881             <para>Request the server to use broadcast messages before
 882             the IP address has been configured. This is necessary for
 883             devices that cannot receive RAW packets, or that cannot
 884             receive packets at all before an IP address has been
 885             configured. On the other hand, this must not be enabled on
 886             networks where broadcasts are filtered out.</para>
 887           </listitem>
 888         </varlistentry>
 889
 890         <varlistentry>
 891           <term><varname>RouteMetric=</varname></term>
 892           <listitem>
 893             <para>Set the routing metric for routes specified by the
 894             DHCP server.</para>
 895           </listitem>
 896         </varlistentry>
 897       </variablelist>
 898     </refsect1>
 899
 900   <refsect1>
 901     <title>[DHCPServer] Section Options</title>
 902     <para>The <literal>[DHCPServer]</literal> section contains
 903     settings for the DHCP server, if enabled via the
 904     <varname>DHCPServer=</varname> option described above:</para>
 905
 906     <variablelist class='network-directives'>
 907
 908       <varlistentry>
 909         <term><varname>PoolOffset=</varname></term>
 910         <term><varname>PoolSize=</varname></term>
 911
 912         <listitem><para>Configures the pool of addresses to hand out. The pool
 913         is a contiguous sequence of IP addresses in the subnet configured for
 914         the server address, which does not include the subnet nor the broadcast
 915         address. <varname>PoolOffset=</varname> takes the offset of the pool
 916         from the start of subnet, or zero to use the default value.
 917         <varname>PoolSize=</varname> takes the number of IP addresses in the
 918         pool or zero to use the default value. By default, the pool starts at
 919         the first address after the subnet address and takes up the rest of
 920         the subnet, excluding the broadcast address. If the pool includes
 921         the server address (the default), this is reserved and not handed
 922         out to clients.</para></listitem>
 923       </varlistentry>
 924
 925       <varlistentry>
 926         <term><varname>DefaultLeaseTimeSec=</varname></term>
 927         <term><varname>MaxLeaseTimeSec=</varname></term>
 928
 929         <listitem><para>Control the default and maximum DHCP lease
 930         time to pass to clients. These settings take time values in seconds or
 931         another common time unit, depending on the suffix. The default
 932         lease time is used for clients that did not ask for a specific
 933         lease time. If a client asks for a lease time longer than the
 934         maximum lease time, it is automatically shortened to the
 935         specified time. The default lease time defaults to 1h, the
 936         maximum lease time to 12h. Shorter lease times are beneficial
 937         if the configuration data in DHCP leases changes frequently
 938         and clients shall learn the new settings with shorter
 939         latencies. Longer lease times reduce the generated DHCP
 940         network traffic.</para></listitem>
 941       </varlistentry>
 942
 943       <varlistentry>
 944         <term><varname>EmitDNS=</varname></term>
 945         <term><varname>DNS=</varname></term>
 946
 947         <listitem><para>Configures whether the DHCP leases handed out
 948         to clients shall contain DNS server information. The
 949         <varname>EmitDNS=</varname> setting takes a boolean argument
 950         and defaults to <literal>yes</literal>. The DNS servers to
 951         pass to clients may be configured with the
 952         <varname>DNS=</varname> option, which takes a list of IPv4
 953         addresses. If the <varname>EmitDNS=</varname> option is
 954         enabled but no servers configured, the servers are
 955         automatically propagated from an "uplink" interface that has
 956         appropriate servers set. The "uplink" interface is determined
 957         by the default route of the system with the highest
 958         priority. Note that this information is acquired at the time
 959         the lease is handed out, and does not take uplink interfaces
 960         into account that acquire DNS or NTP server information at a
 961         later point. DNS server propagation does not take
 962         <filename>/etc/resolv.conf</filename> into account. Also, note
 963         that the leases are not refreshed if the uplink network
 964         configuration changes. To ensure clients regularly acquire the
 965         most current uplink DNS server information, it is thus
 966         advisable to shorten the DHCP lease time via
 967         <varname>MaxLeaseTimeSec=</varname> described
 968         above.</para></listitem>
 969       </varlistentry>
 970
 971       <varlistentry>
 972         <term><varname>EmitNTP=</varname></term>
 973         <term><varname>NTP=</varname></term>
 974
 975         <listitem><para>Similar to the <varname>EmitDNS=</varname> and
 976         <varname>DNS=</varname> settings described above, these
 977         settings configure whether and what NTP server information
 978         shall be emitted as part of the DHCP lease. The same syntax,
 979         propagation semantics and defaults apply as for
 980         <varname>EmitDNS=</varname> and
 981         <varname>DNS=</varname>.</para></listitem>
 982       </varlistentry>
 983
 984       <varlistentry>
 985         <term><varname>EmitRouter=</varname></term>
 986
 987         <listitem><para>Similar to the <varname>EmitDNS=</varname>
 988         setting described above, this setting configures whether the
 989         DHCP lease should contain the router option. The same syntax,
 990         propagation semantics and defaults apply as for
 991         <varname>EmitDNS=</varname>.</para></listitem>
 992       </varlistentry>
 993
 994       <varlistentry>
 995         <term><varname>EmitTimezone=</varname></term>
 996         <term><varname>Timezone=</varname></term>
 997
 998         <listitem><para>Configures whether the DHCP leases handed out
 999         to clients shall contain timezone information. The
1000         <varname>EmitTimezone=</varname> setting takes a boolean
1001         argument and defaults to <literal>yes</literal>. The
1002         <varname>Timezone=</varname> setting takes a timezone string
1003         (such as <literal>Europe/Berlin</literal> or
1004         <literal>UTC</literal>) to pass to clients. If no explicit
1005         timezone is set, the system timezone of the local host is
1006         propagated, as determined by the
1007         <filename>/etc/localtime</filename> symlink.</para></listitem>
1008       </varlistentry>
1009
1010     </variablelist>
1011   </refsect1>
1012
1013   <refsect1>
1014     <title>[Bridge] Section Options</title>
1015       <para>The <literal>[Bridge]</literal> section accepts the
1016       following keys.</para>
1017       <variablelist class='network-directives'>
1018         <varlistentry>
1019           <term><varname>UnicastFlood=</varname></term>
1020           <listitem>
1021             <para>A boolean. Controls whether the bridge should flood
1022             traffic for which an FDB entry is missing and the destination
1023             is unknown through this port. Defaults to on.
1024             </para>
1025           </listitem>
1026         </varlistentry>
1027         <varlistentry>
1028           <term><varname>HairPin=</varname></term>
1029           <listitem>
1030             <para>A boolean. Configures whether traffic may be sent back
1031             out of the port on which it was received. By default, this
1032             flag is false, and the bridge will not forward traffic back
1033             out of the receiving port.</para>
1034           </listitem>
1035         </varlistentry>
1036         <varlistentry>
1037           <term><varname>UseBPDU=</varname></term>
1038           <listitem>
1039             <para>A boolean. Configures whether STP Bridge Protocol Data Units will be
1040             processed by the bridge port. Defaults to yes.</para>
1041           </listitem>
1042         </varlistentry>
1043         <varlistentry>
1044           <term><varname>FastLeave=</varname></term>
1045           <listitem>
1046             <para>A boolean. This flag allows the bridge to immediately stop multicast
1047             traffic on a port that receives an IGMP Leave message. It is only used with
1048             IGMP snooping if enabled on the bridge. Defaults to off.</para>
1049           </listitem>
1050         </varlistentry>
1051         <varlistentry>
1052           <term><varname>AllowPortToBeRoot=</varname></term>
1053           <listitem>
1054             <para>A boolean. Configures whether a given port is allowed to
1055             become a root port. Only used when STP is enabled on the bridge.
1056             Defaults to on.</para>
1057           </listitem>
1058         </varlistentry>
1059         <varlistentry>
1060           <term><varname>Cost=</varname></term>
1061           <listitem>
1062             <para>Sets the "cost" of sending packets of this interface.
1063             Each port in a bridge may have a different speed and the cost
1064             is used to decide which link to use. Faster interfaces
1065             should have lower costs.</para>
1066           </listitem>
1067         </varlistentry>
1068       </variablelist>
1069   </refsect1>
1070   <refsect1>
1071     <title>[BridgeFDB] Section Options</title>
1072       <para>The <literal>[BridgeFDB]</literal> section manages the
1073       forwarding database table of a port and accepts the following
1074       keys. Specify several <literal>[BridgeFDB]</literal> sections to
1075       configure several static MAC table entries.</para>
1076
1077       <variablelist class='network-directives'>
1078         <varlistentry>
1079           <term><varname>MACAddress=</varname></term>
1080           <listitem>
1081             <para>As in the <literal>[Network]</literal> section. This
1082             key is mandatory.</para>
1083           </listitem>
1084         </varlistentry>
1085         <varlistentry>
1086           <term><varname>VLANId=</varname></term>
1087           <listitem>
1088             <para>The VLAN ID for the new static MAC table entry. If
1089             omitted, no VLAN ID info is appended to the new static MAC
1090             table entry.</para>
1091           </listitem>
1092         </varlistentry>
1093       </variablelist>
1094   </refsect1>
1095
1096   <refsect1>
1097     <title>Example</title>
1098     <example>
1099       <title>/etc/systemd/network/50-static.network</title>
1100
1101       <programlisting>[Match]
1102 Name=enp2s0
1103
1104 [Network]
1105 Address=192.168.0.15/24
1106 Gateway=192.168.0.1</programlisting>
1107     </example>
1108
1109     <example>
1110       <title>/etc/systemd/network/80-dhcp.network</title>
1111
1112       <programlisting>[Match]
1113 Name=en*
1114
1115 [Network]
1116 DHCP=yes</programlisting>
1117     </example>
1118
1119     <example>
1120       <title>/etc/systemd/network/25-bridge-static.network</title>
1121
1122       <programlisting>[Match]
1123 Name=bridge0
1124
1125 [Network]
1126 Address=192.168.0.15/24
1127 Gateway=192.168.0.1
1128 DNS=192.168.0.1</programlisting>
1129     </example>
1130
1131     <example>
1132       <title>/etc/systemd/network/25-bridge-slave-interface.network</title>
1133
1134       <programlisting>[Match]
1135 Name=enp2s0
1136
1137 [Network]
1138 Bridge=bridge0</programlisting>
1139     </example>
1140     <example>
1141       <title>/etc/systemd/network/25-ipip.network</title>
1142
1143       <programlisting>[Match]
1144 Name=em1
1145
1146 [Network]
1147 Tunnel=ipip-tun</programlisting>
1148     </example>
1149
1150     <example>
1151       <title>/etc/systemd/network/25-sit.network</title>
1152
1153       <programlisting>[Match]
1154 Name=em1
1155
1156 [Network]
1157 Tunnel=sit-tun</programlisting>
1158     </example>
1159
1160     <example>
1161       <title>/etc/systemd/network/25-gre.network</title>
1162
1163       <programlisting>[Match]
1164 Name=em1
1165
1166 [Network]
1167 Tunnel=gre-tun</programlisting>
1168     </example>
1169
1170     <example>
1171       <title>/etc/systemd/network/25-vti.network</title>
1172
1173       <programlisting>[Match]
1174 Name=em1
1175
1176 [Network]
1177 Tunnel=vti-tun</programlisting>
1178     </example>
1179
1180     <example>
1181       <title>/etc/systemd/network/25-bond.network</title>
1182
1183       <programlisting>[Match]
1184 Name=bond1
1185
1186 [Network]
1187 DHCP=yes
1188 </programlisting>
1189     </example>
1190
1191   </refsect1>
1192
1193   <refsect1>
1194     <title>See Also</title>
1195     <para>
1196       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1197       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1198       <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1199       <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1200       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1201     </para>
1202   </refsect1>
1203
1204 </refentry>