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       <varlistentry>
 208         <term><varname>IAID=</varname></term>
 209         <listitem>
 210           <para>Identity Association Identifier for the interface, a 32-bit unsigned integer.</para>
 211         </listitem>
 212       </varlistentry>
 213     </variablelist>
 214   </refsect1>
 215
 216   <refsect1>
 217     <title>[Network] Section Options</title>
 218
 219       <para>The <literal>[Network]</literal> section accepts the following keys:</para>
 220
 221       <variablelist class='network-directives'>
 222         <varlistentry>
 223           <term><varname>Description=</varname></term>
 224           <listitem>
 225             <para>A description of the device. This is only used for
 226             presentation purposes.</para>
 227           </listitem>
 228         </varlistentry>
 229         <varlistentry>
 230           <term><varname>DHCP=</varname></term>
 231           <listitem>
 232             <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
 233             <literal>yes</literal>, <literal>no</literal>,
 234             <literal>ipv4</literal>, or <literal>ipv6</literal>.</para>
 235
 236             <para>Note that DHCPv6 will by default be triggered by Router
 237             Advertisement, if that is enabled, regardless of this parameter.
 238             By enabling DHCPv6 support explicitly, the DHCPv6 client will
 239             be started regardless of the presence of routers on the link,
 240             or what flags the routers pass. See
 241             <literal>IPv6AcceptRouterAdvertisements=</literal>.</para>
 242
 243             <para>Furthermore, note that by default the domain name
 244             specified through DHCP is not used for name resolution.
 245             See option <option>UseDomains=</option> below.</para>
 246           </listitem>
 247         </varlistentry>
 248         <varlistentry>
 249           <term><varname>DHCPServer=</varname></term>
 250           <listitem>
 251             <para>A boolean. Enables DHCPv4 server support. Defaults
 252             to <literal>no</literal>. Further settings for the DHCP
 253             server may be set in the <literal>[DHCPServer]</literal>
 254             section described below.</para>
 255           </listitem>
 256         </varlistentry>
 257         <varlistentry>
 258           <term><varname>LinkLocalAddressing=</varname></term>
 259           <listitem>
 260             <para>Enables link-local address autoconfiguration. Accepts
 261             <literal>yes</literal>, <literal>no</literal>,
 262             <literal>ipv4</literal>, or <literal>ipv6</literal>. Defaults to
 263             <literal>ipv6</literal>.</para>
 264           </listitem>
 265         </varlistentry>
 266         <varlistentry>
 267           <term><varname>IPv4LLRoute=</varname></term>
 268           <listitem>
 269             <para>A boolean. When true, sets up the route needed for
 270             non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
 271             to false.
 272             </para>
 273           </listitem>
 274         </varlistentry>
 275         <varlistentry>
 276           <term><varname>IPv6Token=</varname></term>
 277           <listitem>
 278             <para>An IPv6 address with the top 64 bits unset. When set, indicates the
 279             64-bit interface part of SLAAC IPv6 addresses for this link. Note that
 280             the token is only ever used for SLAAC, and not for DHCPv6 addresses, even
 281             in the case DHCP is requested by router advertisement. By default, the
 282             token is autogenerated.</para>
 283           </listitem>
 284         </varlistentry>
 285         <varlistentry>
 286           <term><varname>LLMNR=</varname></term>
 287           <listitem>
 288             <para>A boolean or <literal>resolve</literal>. When true,
 289             enables <ulink
 290             url="https://tools.ietf.org/html/rfc4795">Link-Local
 291             Multicast Name Resolution</ulink> on the link. When set to
 292             <literal>resolve</literal>, only resolution is enabled,
 293             but not host registration and announcement. Defaults to
 294             true. This setting is read by
 295             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 296           </listitem>
 297         </varlistentry>
 298         <varlistentry>
 299           <term><varname>MulticastDNS=</varname></term>
 300           <listitem>
 301             <para>A boolean or <literal>resolve</literal>. When true,
 302             enables <ulink
 303             url="https://tools.ietf.org/html/rfc6762">Multicast
 304             DNS</ulink> support on the link. When set to
 305             <literal>resolve</literal>, only resolution is enabled,
 306             but not host or service registration and
 307             announcement. Defaults to false. This setting is read by
 308             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 309           </listitem>
 310         </varlistentry>
 311         <varlistentry>
 312           <term><varname>DNSSEC=</varname></term>
 313           <listitem>
 314             <para>A boolean or
 315             <literal>allow-downgrade</literal>. When true, enables
 316             <ulink
 317             url="https://tools.ietf.org/html/rfc4033">DNSSEC</ulink>
 318             DNS validation support on the link. When set to
 319             <literal>allow-downgrade</literal>, compatibility with
 320             non-DNSSEC capable networks is increased, by automatically
 321             turning off DNSEC in this case. This option defines a
 322             per-interface setting for
 323             <citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
 324             global <varname>DNSSEC=</varname> option. Defaults to
 325             false. This setting is read by
 326             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 327           </listitem>
 328         </varlistentry>
 329         <varlistentry>
 330           <term><varname>DNSSECNegativeTrustAnchors=</varname></term>
 331           <listitem><para>A space-separated list of DNSSEC negative
 332           trust anchor domains. If specified and DNSSEC is enabled,
 333           look-ups done via the interface's DNS server will be subject
 334           to the list of negative trust anchors, and not require
 335           authentication for the specified domains, or anything below
 336           it. Use this to disable DNSSEC authentication for specific
 337           private domains, that cannot be proven valid using the
 338           Internet DNS hierarchy. Defaults to the empty list. This
 339           setting is read by
 340           <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 341           </listitem>
 342         </varlistentry>
 343         <varlistentry>
 344           <term><varname>LLDP=</varname></term>
 345           <listitem>
 346             <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
 347             implemented on professional routers and bridges which announces which physical port a system is connected
 348             to, as well as other related data. Accepts a boolean or the special value
 349             <literal>routers-only</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
 350             neighbors maintained. If <literal>routers-only</literal> is set only LLDP data of various types of routers
 351             is collected and LLDP data about other types of devices ignored (such as stations, telephones and
 352             others). If false, LLDP reception is disabled. Defaults to <literal>routers-only</literal>. Use
 353             <citerefentry><refentrytitle>networkctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
 354             collected neighbor data. LLDP is only available on Ethernet links. See <varname>EmitLLDP=</varname> below
 355             for enabling LLDP packet emission from the local system.
 356             </para>
 357           </listitem>
 358         </varlistentry>
 359         <varlistentry>
 360           <term><varname>EmitLLDP=</varname></term>
 361           <listitem>
 362             <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter and defaults to
 363             false. If enabled a short LLDP packet with information about the local system is sent out in regular
 364             intervals on the link. The LLDP packet will contain information about the local host name, the local
 365             machine ID (as stored in
 366             <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
 367             local interface name, as well as the pretty hostname of the system (as set in
 368             <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
 369             emission is only available on Ethernet links. Note that this setting passed data suitable for
 370             identification of host to the network and should thus not be used on untrusted networks, where such
 371             identification data should not be made available. Use this option to enable other systems to identify on
 372             which interface they are connected to this system. See <varname>LLDP=</varname> above for an option to
 373             enable LLDP reception.</para>
 374           </listitem>
 375         </varlistentry>
 376         <varlistentry>
 377           <term><varname>BindCarrier=</varname></term>
 378           <listitem>
 379             <para>A link name or a list of link names. When set, controls the behavior of the current
 380             link. When all links in the list are in an operational down state, the current link is brought
 381             down. When at least one link has carrier, the current interface is brought up.
 382             </para>
 383           </listitem>
 384         </varlistentry>
 385         <varlistentry>
 386           <term><varname>Address=</varname></term>
 387           <listitem>
 388             <para>A static IPv4 or IPv6 address and its prefix length,
 389             separated by a <literal>/</literal> character. Specify
 390             this key more than once to configure several addresses.
 391             The format of the address must be as described in
 392             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 393             This is a short-hand for an [Address] section only
 394             containing an Address key (see below). This option may be
 395             specified more than once.
 396             </para>
 397
 398             <para>If the specified address is 0.0.0.0 (for IPv4) or
 399             [::] (for IPv6), a new address range of the requested size
 400             is automatically allocated from a system-wide pool of
 401             unused ranges. The allocated range is checked against all
 402             current network interfaces and all known network
 403             configuration files to avoid address range conflicts. The
 404             default system-wide pool consists of 192.168.0.0/16,
 405             172.16.0.0/12 and 10.0.0.0/8 for IPv4, and fc00::/7 for
 406             IPv6. This functionality is useful to manage a large
 407             number of dynamically created network interfaces with the
 408             same network configuration and automatic address range
 409             assignment.</para>
 410
 411           </listitem>
 412         </varlistentry>
 413         <varlistentry>
 414           <term><varname>Gateway=</varname></term>
 415           <listitem>
 416             <para>The gateway address, which must be in the format
 417             described in
 418             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 419             This is a short-hand for a [Route] section only containing
 420             a Gateway key. This option may be specified more than
 421             once.</para>
 422           </listitem>
 423         </varlistentry>
 424         <varlistentry>
 425           <term><varname>DNS=</varname></term>
 426           <listitem>
 427             <para>A DNS server address, which must be in the format
 428             described in
 429             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 430             This option may be specified more than once. This setting is read by
 431             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 432           </listitem>
 433         </varlistentry>
 434         <varlistentry>
 435           <term><varname>Domains=</varname></term>
 436           <listitem>
 437             <para>The domains used for DNS host name resolution on this link. Takes a list of DNS domain names which
 438             are used as search suffixes for extending single-label host names (host names containing no dots) to become
 439             fully qualified domain names (FQDNs). If a single-label host name is resolved on this interface, each of
 440             the specified search domains are appended to it in turn, converting it into a fully qualified domain name,
 441             until one of them may be successfully resolved.</para>
 442
 443             <para>The specified domains are also used for routing of DNS queries: look-ups for host names ending in the
 444             domains specified here are preferably routed to the DNS servers configured for this interface. If a domain
 445             name is prefixed with <literal>~</literal>, the domain name becomes a pure "routing" domain, is used for
 446             DNS query routing purposes only and is not used in the described domain search logic. By specifying a
 447             routing domain of <literal>~.</literal> (the tilde indicating definition of a routing domain, the dot
 448             referring to the DNS root domain which is the implied suffix of all valid DNS names) it is possible to
 449             route all DNS traffic preferably to the DNS server specified for this interface. The route domain logic is
 450             particularly useful on multi-homed hosts with DNS servers serving particular private DNS zones on each
 451             interface.</para>
 452
 453             <para>This setting is read by
 454             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 455           </listitem>
 456         </varlistentry>
 457         <varlistentry>
 458           <term><varname>NTP=</varname></term>
 459           <listitem>
 460             <para>An NTP server address. This option may be specified more than once. This setting is read by
 461             <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 462           </listitem>
 463         </varlistentry>
 464         <varlistentry>
 465           <term><varname>IPForward=</varname></term>
 466           <listitem><para>Configures IP packet forwarding for the
 467           system. If enabled, incoming packets on any network
 468           interface will be forwarded to any other interfaces
 469           according to the routing table. Takes either a boolean
 470           argument, or the values <literal>ipv4</literal> or
 471           <literal>ipv6</literal>, which only enable IP packet
 472           forwarding for the specified address family.  This controls
 473           the <filename>net.ipv4.ip_forward</filename> and
 474           <filename>net.ipv6.conf.all.forwarding</filename> sysctl
 475           options of the network interface (see <ulink
 476           url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink>
 477           for details about sysctl options). Defaults to
 478           <literal>no</literal>.</para>
 479
 480           <para>Note: this setting controls a global kernel option,
 481           and does so one way only: if a network that has this setting
 482           enabled is set up the global setting is turned on.  However,
 483           it is never turned off again, even after all networks with
 484           this setting enabled are shut down again.</para>
 485
 486           <para>To allow IP packet forwarding only between specific
 487           network interfaces use a firewall.</para>
 488           </listitem>
 489         </varlistentry>
 490         <varlistentry>
 491           <term><varname>IPMasquerade=</varname></term>
 492           <listitem><para>Configures IP masquerading for the network
 493           interface. If enabled, packets forwarded from the network
 494           interface will be appear as coming from the local host.
 495           Takes a boolean argument. Implies
 496           <varname>IPForward=ipv4</varname>. Defaults to
 497           <literal>no</literal>.</para></listitem>
 498         </varlistentry>
 499         <varlistentry>
 500           <term><varname>IPv6PrivacyExtensions=</varname></term>
 501           <listitem><para>Configures use of stateless temporary
 502           addresses that change over time (see <ulink
 503           url="https://tools.ietf.org/html/rfc4941">RFC 4941</ulink>,
 504           Privacy Extensions for Stateless Address Autoconfiguration
 505           in IPv6). Takes a boolean or the special values
 506           <literal>prefer-public</literal> and
 507           <literal>kernel</literal>. When true, enables the privacy
 508           extensions and prefers temporary addresses over public
 509           addresses. When <literal>prefer-public</literal>, enables the
 510           privacy extensions, but prefers public addresses over
 511           temporary addresses. When false, the privacy extensions
 512           remain disabled. When <literal>kernel</literal>, the kernel's
 513           default setting will be left in place.  Defaults to
 514           <literal>no</literal>.</para></listitem>
 515         </varlistentry>
 516         <varlistentry>
 517           <term><varname>IPv6AcceptRouterAdvertisements=</varname></term>
 518           <listitem><para>Force the setting of the <filename>accept_ra</filename>
 519           (router advertisements) setting for the interface.
 520           When unset, the kernel default is used, and router
 521           advertisements are accepted only when local forwarding
 522           is disabled for that interface.
 523           When router advertisements are accepted, they will
 524           trigger the start of the DHCPv6 client if the relevant
 525           flags are passed, or if no routers are found on the link.
 526           Takes a boolean. If true, router advertisements are
 527           accepted, when false, router advertisements are ignored,
 528           independently of the local forwarding state.</para>
 529
 530           <para>See
 531           <ulink url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink>
 532           in the kernel documentation, but note that systemd's
 533           setting of <constant>1</constant> corresponds to
 534           kernel's setting of <constant>2</constant>.</para>
 535         </listitem>
 536         </varlistentry>
 537         <varlistentry>
 538           <term><varname>IPv6DuplicateAddressDetection=</varname></term>
 539           <listitem><para>Configures the amount of IPv6 Duplicate
 540           Address Detection (DAD) probes to send. Defaults to unset.
 541         </para></listitem>
 542         </varlistentry>
 543         <varlistentry>
 544           <term><varname>IPv6HopLimit=</varname></term>
 545           <listitem><para>Configures IPv6 Hop Limit. For each router that
 546           forwards the packet, the hop limit is decremented by 1. When the
 547           hop limit field reaches zero, the packet is discarded.
 548           Defaults to unset.
 549         </para></listitem>
 550         </varlistentry>
 551         <varlistentry>
 552           <term><varname>ProxyARP=</varname></term>
 553           <listitem><para>A boolean. Configures proxy ARP. Proxy ARP is the technique in which one host,
 554           usually a router, answers ARP requests intended for another machine. By "faking" its identity,
 555           the router accepts responsibility for routing packets to the "real" destination. (see <ulink
 556           url="https://tools.ietf.org/html/rfc1027">RFC 1027</ulink>.
 557           Defaults to unset.
 558         </para></listitem>
 559         </varlistentry>
 560         <varlistentry>
 561           <term><varname>Bridge=</varname></term>
 562           <listitem>
 563             <para>The name of the bridge to add the link to.</para>
 564           </listitem>
 565         </varlistentry>
 566         <varlistentry>
 567           <term><varname>Bond=</varname></term>
 568           <listitem>
 569             <para>The name of the bond to add the link to.</para>
 570           </listitem>
 571         </varlistentry>
 572         <varlistentry>
 573           <term><varname>VLAN=</varname></term>
 574           <listitem>
 575             <para>The name of a VLAN to create on the link. This
 576             option may be specified more than once.</para>
 577           </listitem>
 578         </varlistentry>
 579         <varlistentry>
 580           <term><varname>MACVLAN=</varname></term>
 581           <listitem>
 582             <para>The name of a MACVLAN to create on the link. This
 583             option may be specified more than once.</para>
 584           </listitem>
 585         </varlistentry>
 586         <varlistentry>
 587           <term><varname>VXLAN=</varname></term>
 588           <listitem>
 589             <para>The name of a VXLAN to create on the link. This
 590             option may be specified more than once.</para>
 591           </listitem>
 592         </varlistentry>
 593         <varlistentry>
 594           <term><varname>Tunnel=</varname></term>
 595           <listitem>
 596             <para>The name of a Tunnel to create on the link. This
 597             option may be specified more than once.</para>
 598           </listitem>
 599         </varlistentry>
 600       </variablelist>
 601
 602   </refsect1>
 603
 604   <refsect1>
 605     <title>[Address] Section Options</title>
 606
 607       <para>An <literal>[Address]</literal> section accepts the
 608       following keys. Specify several <literal>[Address]</literal>
 609       sections to configure several addresses.</para>
 610
 611       <variablelist class='network-directives'>
 612         <varlistentry>
 613           <term><varname>Address=</varname></term>
 614           <listitem>
 615             <para>As in the <literal>[Network]</literal> section. This
 616             key is mandatory.</para>
 617           </listitem>
 618         </varlistentry>
 619         <varlistentry>
 620           <term><varname>Peer=</varname></term>
 621           <listitem>
 622             <para>The peer address in a point-to-point connection.
 623             Accepts the same format as the <literal>Address</literal>
 624             key.</para>
 625           </listitem>
 626         </varlistentry>
 627         <varlistentry>
 628           <term><varname>Broadcast=</varname></term>
 629           <listitem>
 630             <para>The broadcast address, which must be in the format
 631             described in
 632             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 633             This key only applies to IPv4 addresses. If it is not
 634             given, it is derived from the <literal>Address</literal>
 635             key.</para>
 636           </listitem>
 637         </varlistentry>
 638         <varlistentry>
 639           <term><varname>Label=</varname></term>
 640           <listitem>
 641             <para>An address label.</para>
 642           </listitem>
 643         </varlistentry>
 644       </variablelist>
 645   </refsect1>
 646
 647   <refsect1>
 648     <title>[Route] Section Options</title>
 649       <para>The <literal>[Route]</literal> section accepts the
 650       following keys. Specify several <literal>[Route]</literal>
 651       sections to configure several routes.</para>
 652
 653       <variablelist class='network-directives'>
 654         <varlistentry>
 655           <term><varname>Gateway=</varname></term>
 656           <listitem>
 657             <para>As in the <literal>[Network]</literal> section.</para>
 658           </listitem>
 659         </varlistentry>
 660         <varlistentry>
 661           <term><varname>Destination=</varname></term>
 662           <listitem>
 663             <para>The destination prefix of the route. Possibly
 664             followed by a slash and the prefix length. If omitted, a
 665             full-length host route is assumed.</para>
 666           </listitem>
 667         </varlistentry>
 668         <varlistentry>
 669           <term><varname>Source=</varname></term>
 670           <listitem>
 671             <para>The source prefix of the route. Possibly followed by
 672             a slash and the prefix length. If omitted, a full-length
 673             host route is assumed.</para>
 674           </listitem>
 675         </varlistentry>
 676         <varlistentry>
 677           <term><varname>Metric=</varname></term>
 678           <listitem>
 679             <para>The metric of the route (an unsigned integer).</para>
 680           </listitem>
 681         </varlistentry>
 682         <varlistentry>
 683           <term><varname>Scope=</varname></term>
 684           <listitem>
 685             <para>The scope of the route, which can be <literal>global</literal>,
 686             <literal>link</literal> or <literal>host</literal>. Defaults to
 687             <literal>global</literal>.</para>
 688           </listitem>
 689         </varlistentry>
 690         <varlistentry>
 691           <term><varname>PreferredSource=</varname></term>
 692           <listitem>
 693             <para>The preferred source address of the route. The address
 694             must be in the format described in
 695             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
 696           </listitem>
 697         </varlistentry>
 698       </variablelist>
 699   </refsect1>
 700
 701   <refsect1>
 702     <title>[DHCP] Section Options</title>
 703       <para>The <literal>[DHCP]</literal> section configures the
 704       DHCPv4 and DHCP6 client, if it is enabled with the
 705       <varname>DHCP=</varname> setting described above:</para>
 706
 707       <variablelist class='network-directives'>
 708         <varlistentry>
 709           <term><varname>UseDNS=</varname></term>
 710           <listitem>
 711             <para>When true (the default), the DNS servers received
 712             from the DHCP server will be used and take precedence over
 713             any statically configured ones.</para>
 714
 715             <para>This corresponds to the <option>nameserver</option>
 716             option in <citerefentry
 717             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 718           </listitem>
 719         </varlistentry>
 720         <varlistentry>
 721           <term><varname>UseNTP=</varname></term>
 722           <listitem>
 723             <para>When true (the default), the NTP servers received
 724             from the DHCP server will be used by systemd-timesyncd
 725             and take precedence over any statically configured ones.</para>
 726           </listitem>
 727         </varlistentry>
 728         <varlistentry>
 729           <term><varname>UseMTU=</varname></term>
 730           <listitem>
 731             <para>When true, the interface maximum transmission unit
 732             from the DHCP server will be used on the current link.
 733             Defaults to false.</para>
 734           </listitem>
 735         </varlistentry>
 736         <varlistentry>
 737           <term><varname>SendHostname=</varname></term>
 738           <listitem>
 739             <para>When true (the default), the machine's hostname will
 740             be sent to the DHCP server.</para>
 741           </listitem>
 742         </varlistentry>
 743         <varlistentry>
 744           <term><varname>UseHostname=</varname></term>
 745           <listitem>
 746             <para>When true (the default), the hostname received from
 747             the DHCP server will be set as the transient hostname of the system
 748             </para>
 749           </listitem>
 750         </varlistentry>
 751         <varlistentry>
 752         <term><varname>Hostname=</varname></term>
 753         <listitem>
 754           <para>Use this value for the hostname which is sent to the
 755           DHCP server, instead of machine's hostname.</para>
 756         </listitem>
 757       </varlistentry>
 758         <varlistentry>
 759           <term><varname>UseDomains=</varname></term>
 760           <listitem>
 761             <para>Takes a boolean argument, or the special value <literal>route</literal>. When true, the domain name
 762             received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
 763             the <option>Domains=</option> setting. If set to <literal>route</literal>, the domain name received from
 764             the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
 765             the <option>Domains=</option> setting when the argument is prefixed with <literal>~</literal>. Defaults to
 766             false.</para>
 767
 768             <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
 769             of all host names, in particular to single-label names. It is generally safer to use the supplied domain
 770             only as routing domain, rather than as search domain, in order to not have it affect local resolution of
 771             single-label names.</para>
 772
 773             <para>When set to true, this setting corresponds to the <option>domain</option> option in <citerefentry
 774             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 775           </listitem>
 776         </varlistentry>
 777         <varlistentry>
 778           <term><varname>UseRoutes=</varname></term>
 779           <listitem>
 780             <para>When true (the default), the static routes will be
 781             requested from the DHCP server and added to the routing
 782             table with a metric of 1024.</para>
 783           </listitem>
 784         </varlistentry>
 785
 786         <varlistentry>
 787           <term><varname>UseTimezone=</varname></term>
 788
 789           <listitem><para>When true, the timezone received from the
 790           DHCP server will be set as timezone of the local
 791           system. Defaults to <literal>no</literal>.</para></listitem>
 792         </varlistentry>
 793
 794         <varlistentry>
 795           <term><varname>CriticalConnection=</varname></term>
 796           <listitem>
 797             <para>When true, the connection will never be torn down
 798             even if the DHCP lease expires. This is contrary to the
 799             DHCP specification, but may be the best choice if, say,
 800             the root filesystem relies on this connection. Defaults to
 801             false.</para>
 802           </listitem>
 803         </varlistentry>
 804         <varlistentry>
 805           <term><varname>ClientIdentifier=</varname></term>
 806           <listitem>
 807             <para>DHCP client identifier to use. Either <literal>mac</literal>
 808             to use the MAC address of the link or <literal>duid</literal>
 809             (the default) to use a RFC4361-compliant Client ID.</para>
 810           </listitem>
 811         </varlistentry>
 812         <varlistentry>
 813           <term><varname>VendorClassIdentifier=</varname></term>
 814           <listitem>
 815             <para>The vendor class identifier used to identify vendor
 816             type and configuration.</para>
 817           </listitem>
 818         </varlistentry>
 819         <varlistentry>
 820           <term><varname>RequestBroadcast=</varname></term>
 821           <listitem>
 822             <para>Request the server to use broadcast messages before
 823             the IP address has been configured. This is necessary for
 824             devices that cannot receive RAW packets, or that cannot
 825             receive packets at all before an IP address has been
 826             configured. On the other hand, this must not be enabled on
 827             networks where broadcasts are filtered out.</para>
 828           </listitem>
 829         </varlistentry>
 830         <varlistentry>
 831           <term><varname>RouteMetric=</varname></term>
 832           <listitem>
 833             <para>Set the routing metric for routes specified by the
 834             DHCP server.</para>
 835           </listitem>
 836         </varlistentry>
 837       </variablelist>
 838
 839   </refsect1>
 840
 841   <refsect1>
 842     <title>[DUID] Section Options</title>
 843
 844     <para>This section configures the DHCP Unique Identifier (DUID) value used by DHCP
 845     protocol. DHCPv6 client protocol sends the DHCP Unique Identifier and the interface
 846     Identity Association Identifier (IAID) to a DHCP server when acquiring a dynamic IPv6
 847     address. DHCPv4 client protocol sends IAID and DUID to the DHCP server when acquiring
 848     a dynamic IPv4 address if <option>ClientIdentifier=duid</option>. IAID and DUID allows a
 849     DHCP server to uniquely identify the machine and the interface requesting a DHCP IP.</para>
 850
 851     <para>The DUID value specified here overrides the DUID that systemd-networkd generates
 852     using the machine-id from the <filename>/etc/machine-id</filename> file, as well as the
 853     global DUID that may be specified in <citerefentry><refentrytitle>networkd.conf
 854     </refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 855
 856     <para>The configured DHCP DUID should conform to the specification in
 857     <ulink url="http://tools.ietf.org/html/rfc3315#section-9">RFC 3315</ulink>,
 858     <ulink url="http://tools.ietf.org/html/rfc6355">RFC 6355</ulink>.</para>
 859
 860     <para>The following options are available in <literal>[DUID]</literal> section:</para>
 861
 862     <variablelist class='network-directives'>
 863
 864       <varlistentry>
 865         <term><varname>RawData=</varname></term>
 866         <listitem><para>Specifies the DUID bytes as a single newline-terminated, hexadecimal
 867         string, with each byte separated by a ':'.</para></listitem>
 868       </varlistentry>
 869
 870     </variablelist>
 871   </refsect1>
 872
 873   <refsect1>
 874     <title>[DHCPServer] Section Options</title>
 875     <para>The <literal>[DHCPServer]</literal> section contains
 876     settings for the DHCP server, if enabled via the
 877     <varname>DHCPServer=</varname> option described above:</para>
 878
 879     <variablelist class='network-directives'>
 880
 881       <varlistentry>
 882         <term><varname>PoolOffset=</varname></term>
 883         <term><varname>PoolSize=</varname></term>
 884
 885         <listitem><para>Configures the pool of addresses to hand out. The pool
 886         is a contiguous sequence of IP addresses in the subnet configured for
 887         the server address, which does not include the subnet nor the broadcast
 888         address. <varname>PoolOffset=</varname> takes the offset of the pool
 889         from the start of subnet, or zero to use the default value.
 890         <varname>PoolSize=</varname> takes the number of IP addresses in the
 891         pool or zero to use the default value. By default, the pool starts at
 892         the first address after the subnet address and takes up the rest of
 893         the subnet, excluding the broadcast address. If the pool includes
 894         the server address (the default), this is reserved and not handed
 895         out to clients.</para></listitem>
 896       </varlistentry>
 897
 898       <varlistentry>
 899         <term><varname>DefaultLeaseTimeSec=</varname></term>
 900         <term><varname>MaxLeaseTimeSec=</varname></term>
 901
 902         <listitem><para>Control the default and maximum DHCP lease
 903         time to pass to clients. These settings take time values in seconds or
 904         another common time unit, depending on the suffix. The default
 905         lease time is used for clients that did not ask for a specific
 906         lease time. If a client asks for a lease time longer than the
 907         maximum lease time, it is automatically shortened to the
 908         specified time. The default lease time defaults to 1h, the
 909         maximum lease time to 12h. Shorter lease times are beneficial
 910         if the configuration data in DHCP leases changes frequently
 911         and clients shall learn the new settings with shorter
 912         latencies. Longer lease times reduce the generated DHCP
 913         network traffic.</para></listitem>
 914       </varlistentry>
 915
 916       <varlistentry>
 917         <term><varname>EmitDNS=</varname></term>
 918         <term><varname>DNS=</varname></term>
 919
 920         <listitem><para>Configures whether the DHCP leases handed out
 921         to clients shall contain DNS server information. The
 922         <varname>EmitDNS=</varname> setting takes a boolean argument
 923         and defaults to <literal>yes</literal>. The DNS servers to
 924         pass to clients may be configured with the
 925         <varname>DNS=</varname> option, which takes a list of IPv4
 926         addresses. If the <varname>EmitDNS=</varname> option is
 927         enabled but no servers configured, the servers are
 928         automatically propagated from an "uplink" interface that has
 929         appropriate servers set. The "uplink" interface is determined
 930         by the default route of the system with the highest
 931         priority. Note that this information is acquired at the time
 932         the lease is handed out, and does not take uplink interfaces
 933         into account that acquire DNS or NTP server information at a
 934         later point. DNS server propagation does not take
 935         <filename>/etc/resolv.conf</filename> into account. Also, note
 936         that the leases are not refreshed if the uplink network
 937         configuration changes. To ensure clients regularly acquire the
 938         most current uplink DNS server information, it is thus
 939         advisable to shorten the DHCP lease time via
 940         <varname>MaxLeaseTimeSec=</varname> described
 941         above.</para></listitem>
 942       </varlistentry>
 943
 944       <varlistentry>
 945         <term><varname>EmitNTP=</varname></term>
 946         <term><varname>NTP=</varname></term>
 947
 948         <listitem><para>Similar to the <varname>EmitDNS=</varname> and
 949         <varname>DNS=</varname> settings described above, these
 950         settings configure whether and what NTP server information
 951         shall be emitted as part of the DHCP lease. The same syntax,
 952         propagation semantics and defaults apply as for
 953         <varname>EmitDNS=</varname> and
 954         <varname>DNS=</varname>.</para></listitem>
 955       </varlistentry>
 956
 957       <varlistentry>
 958         <term><varname>EmitTimezone=</varname></term>
 959         <term><varname>Timezone=</varname></term>
 960
 961         <listitem><para>Configures whether the DHCP leases handed out
 962         to clients shall contain timezone information. The
 963         <varname>EmitTimezone=</varname> setting takes a boolean
 964         argument and defaults to <literal>yes</literal>. The
 965         <varname>Timezone=</varname> setting takes a timezone string
 966         (such as <literal>Europe/Berlin</literal> or
 967         <literal>UTC</literal>) to pass to clients. If no explicit
 968         timezone is set, the system timezone of the local host is
 969         propagated, as determined by the
 970         <filename>/etc/localtime</filename> symlink.</para></listitem>
 971       </varlistentry>
 972
 973     </variablelist>
 974   </refsect1>
 975
 976   <refsect1>
 977     <title>[Bridge] Section Options</title>
 978       <para>The <literal>[Bridge]</literal> section accepts the
 979       following keys.</para>
 980       <variablelist class='network-directives'>
 981         <varlistentry>
 982           <term><varname>UnicastFlood=</varname></term>
 983           <listitem>
 984             <para>A boolean. Controls whether the bridge should flood
 985             traffic for which an FDB entry is missing and the destination
 986             is unknown through this port. Defaults to on.
 987             </para>
 988           </listitem>
 989         </varlistentry>
 990         <varlistentry>
 991           <term><varname>HairPin=</varname></term>
 992           <listitem>
 993             <para>A boolean. Configures whether traffic may be sent back
 994             out of the port on which it was received. By default, this
 995             flag is false, and the bridge will not forward traffic back
 996             out of the receiving port.</para>
 997           </listitem>
 998         </varlistentry>
 999         <varlistentry>
1000           <term><varname>UseBPDU=</varname></term>
1001           <listitem>
1002             <para>A boolean. Configures whether STP Bridge Protocol Data Units will be
1003             processed by the bridge port. Defaults to yes.</para>
1004           </listitem>
1005         </varlistentry>
1006         <varlistentry>
1007           <term><varname>FastLeave=</varname></term>
1008           <listitem>
1009             <para>A boolean. This flag allows the bridge to immediately stop multicast
1010             traffic on a port that receives an IGMP Leave message. It is only used with
1011             IGMP snooping if enabled on the bridge. Defaults to off.</para>
1012           </listitem>
1013         </varlistentry>
1014         <varlistentry>
1015           <term><varname>AllowPortToBeRoot=</varname></term>
1016           <listitem>
1017             <para>A boolean. Configures whether a given port is allowed to
1018             become a root port. Only used when STP is enabled on the bridge.
1019             Defaults to on.</para>
1020           </listitem>
1021         </varlistentry>
1022         <varlistentry>
1023           <term><varname>Cost=</varname></term>
1024           <listitem>
1025             <para>Sets the "cost" of sending packets of this interface.
1026             Each port in a bridge may have a different speed and the cost
1027             is used to decide which link to use. Faster interfaces
1028             should have lower costs.</para>
1029           </listitem>
1030         </varlistentry>
1031       </variablelist>
1032   </refsect1>
1033   <refsect1>
1034     <title>[BridgeFDB] Section Options</title>
1035       <para>The <literal>[BridgeFDB]</literal> section manages the
1036       forwarding database table of a port and accepts the following
1037       keys. Specify several <literal>[BridgeFDB]</literal> sections to
1038       configure several static MAC table entries.</para>
1039
1040       <variablelist class='network-directives'>
1041         <varlistentry>
1042           <term><varname>MACAddress=</varname></term>
1043           <listitem>
1044             <para>As in the <literal>[Network]</literal> section. This
1045             key is mandatory.</para>
1046           </listitem>
1047         </varlistentry>
1048         <varlistentry>
1049           <term><varname>VLANId=</varname></term>
1050           <listitem>
1051             <para>The VLAN ID for the new static MAC table entry. If
1052             omitted, no VLAN ID info is appended to the new static MAC
1053             table entry.</para>
1054           </listitem>
1055         </varlistentry>
1056       </variablelist>
1057   </refsect1>
1058
1059   <refsect1>
1060     <title>Example</title>
1061     <example>
1062       <title>/etc/systemd/network/50-static.network</title>
1063
1064       <programlisting>[Match]
1065 Name=enp2s0
1066
1067 [Network]
1068 Address=192.168.0.15/24
1069 Gateway=192.168.0.1</programlisting>
1070     </example>
1071
1072     <example>
1073       <title>/etc/systemd/network/80-dhcp.network</title>
1074
1075       <programlisting>[Match]
1076 Name=en*
1077
1078 [Network]
1079 DHCP=yes</programlisting>
1080     </example>
1081
1082     <example>
1083       <title>/etc/systemd/network/25-bridge-static.network</title>
1084
1085       <programlisting>[Match]
1086 Name=bridge0
1087
1088 [Network]
1089 Address=192.168.0.15/24
1090 Gateway=192.168.0.1
1091 DNS=192.168.0.1</programlisting>
1092     </example>
1093
1094     <example>
1095       <title>/etc/systemd/network/25-bridge-slave-interface.network</title>
1096
1097       <programlisting>[Match]
1098 Name=enp2s0
1099
1100 [Network]
1101 Bridge=bridge0</programlisting>
1102     </example>
1103     <example>
1104       <title>/etc/systemd/network/25-ipip.network</title>
1105
1106       <programlisting>[Match]
1107 Name=em1
1108
1109 [Network]
1110 Tunnel=ipip-tun</programlisting>
1111     </example>
1112
1113     <example>
1114       <title>/etc/systemd/network/25-sit.network</title>
1115
1116       <programlisting>[Match]
1117 Name=em1
1118
1119 [Network]
1120 Tunnel=sit-tun</programlisting>
1121     </example>
1122
1123     <example>
1124       <title>/etc/systemd/network/25-gre.network</title>
1125
1126       <programlisting>[Match]
1127 Name=em1
1128
1129 [Network]
1130 Tunnel=gre-tun</programlisting>
1131     </example>
1132
1133     <example>
1134       <title>/etc/systemd/network/25-vti.network</title>
1135
1136       <programlisting>[Match]
1137 Name=em1
1138
1139 [Network]
1140 Tunnel=vti-tun</programlisting>
1141     </example>
1142
1143     <example>
1144       <title>/etc/systemd/network/25-bond.network</title>
1145
1146       <programlisting>[Match]
1147 Name=bond1
1148
1149 [Network]
1150 DHCP=yes
1151 </programlisting>
1152     </example>
1153
1154   </refsect1>
1155
1156   <refsect1>
1157     <title>See Also</title>
1158     <para>
1159       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1160       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1161       <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1162       <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1163       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1164     </para>
1165   </refsect1>
1166
1167 </refentry>