man/systemd.network.xml

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