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
  83     <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6 nor IPv6LL enabled,
  84     shall be considered to have no IPv6 support. IPv6 will be automatically disabled for that interface by writing "1"
  85     to <filename>/proc/sys/net/ipv6/conf/<replaceable>ifname</replaceable>/disable_ipv6</filename>.
  86     </para>
  87   </refsect1>
  88
  89   <refsect1>
  90     <title>[Match] Section Options</title>
  91
  92       <para>The network file contains a <literal>[Match]</literal>
  93       section, which determines if a given network file may be applied
  94       to a given device; and a <literal>[Network]</literal> section
  95       specifying how the device should be configured. The first (in
  96       lexical order) of the network files that matches a given device
  97       is applied, all later files are ignored, even if they match as
  98       well.</para>
  99
 100       <para>A network file is said to match a device if each of the
 101       entries in the <literal>[Match]</literal> section matches, or if
 102       the section is empty. The following keys are accepted:</para>
 103
 104       <variablelist class='network-directives'>
 105         <varlistentry>
 106           <term><varname>MACAddress=</varname></term>
 107           <listitem>
 108             <para>The hardware address of the interface (use full colon-delimited hexadecimal, e.g.,
 109             01:23:45:67:89:ab).</para>
 110           </listitem>
 111         </varlistentry>
 112         <varlistentry>
 113           <term><varname>Path=</varname></term>
 114           <listitem>
 115             <para>A whitespace-separated list of shell-style globs
 116             matching the persistent path, as exposed by the udev
 117             property <literal>ID_PATH</literal>.</para>
 118           </listitem>
 119         </varlistentry>
 120         <varlistentry>
 121           <term><varname>Driver=</varname></term>
 122           <listitem>
 123             <para>A whitespace-separated list of shell-style globs
 124             matching the driver currently bound to the device, as
 125             exposed by the udev property <literal>DRIVER</literal>
 126             of its parent device, or if that is not set the driver
 127             as exposed by <literal>ethtool -i</literal> of the
 128             device itself.</para>
 129           </listitem>
 130         </varlistentry>
 131         <varlistentry>
 132           <term><varname>Type=</varname></term>
 133           <listitem>
 134             <para>A whitespace-separated list of shell-style globs
 135             matching the device type, as exposed by the udev property
 136             <literal>DEVTYPE</literal>.</para>
 137           </listitem>
 138         </varlistentry>
 139         <varlistentry>
 140           <term><varname>Name=</varname></term>
 141           <listitem>
 142             <para>A whitespace-separated list of shell-style globs
 143             matching the device name, as exposed by the udev property
 144             <literal>INTERFACE</literal>.</para>
 145           </listitem>
 146         </varlistentry>
 147         <varlistentry>
 148           <term><varname>Host=</varname></term>
 149           <listitem>
 150             <para>Matches against the hostname or machine ID of the
 151             host. See <literal>ConditionHost=</literal> in
 152             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 153             for details.
 154             </para>
 155           </listitem>
 156         </varlistentry>
 157         <varlistentry>
 158           <term><varname>Virtualization=</varname></term>
 159           <listitem>
 160             <para>Checks whether the system is executed in a virtualized
 161             environment and optionally test whether it is a specific
 162             implementation. See <literal>ConditionVirtualization=</literal> in
 163             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 164             for details.
 165             </para>
 166           </listitem>
 167         </varlistentry>
 168         <varlistentry>
 169           <term><varname>KernelCommandLine=</varname></term>
 170           <listitem>
 171             <para>Checks whether a specific kernel command line option is
 172             set (or if prefixed with the exclamation mark unset). See
 173             <literal>ConditionKernelCommandLine=</literal> in
 174             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 175             for details.
 176             </para>
 177           </listitem>
 178         </varlistentry>
 179         <varlistentry>
 180           <term><varname>Architecture=</varname></term>
 181           <listitem>
 182             <para>Checks whether the system is running on a specific
 183             architecture. See <literal>ConditionArchitecture=</literal> in
 184             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 185             for details.
 186             </para>
 187           </listitem>
 188         </varlistentry>
 189       </variablelist>
 190
 191   </refsect1>
 192
 193   <refsect1>
 194     <title>[Link] Section Options</title>
 195
 196     <para> The <literal>[Link]</literal> section accepts the following keys:</para>
 197
 198     <variablelist class='network-directives'>
 199       <varlistentry>
 200         <term><varname>MACAddress=</varname></term>
 201         <listitem>
 202           <para>The hardware address to set for the device.</para>
 203         </listitem>
 204       </varlistentry>
 205       <varlistentry>
 206         <term><varname>MTUBytes=</varname></term>
 207         <listitem>
 208           <para>The maximum transmission unit in bytes to set for the
 209           device. The usual suffixes K, M, G, are supported and are
 210           understood to the base of 1024.</para>
 211           <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
 212           below 1280 (the minimum MTU for IPv6) it will automatically be increased to this value.</para>
 213         </listitem>
 214       </varlistentry>
 215       <varlistentry>
 216         <term><varname>ARP=</varname></term>
 217         <listitem>
 218           <para> A boolean. Enables or disables the ARP (low-level Address Resolution Protocol)
 219           for this interface. Defaults to unset, which means that the kernel default will be used.</para>
 220           <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
 221           interfaces atop a single lower-level physical interface, which will then only serve as a
 222           link/"bridge" device aggregating traffic to the same physical link and not participate in
 223           the network otherwise.</para>
 224         </listitem>
 225       </varlistentry>
 226     </variablelist>
 227   </refsect1>
 228
 229   <refsect1>
 230     <title>[Network] Section Options</title>
 231
 232       <para>The <literal>[Network]</literal> section accepts the following keys:</para>
 233
 234       <variablelist class='network-directives'>
 235         <varlistentry>
 236           <term><varname>Description=</varname></term>
 237           <listitem>
 238             <para>A description of the device. This is only used for
 239             presentation purposes.</para>
 240           </listitem>
 241         </varlistentry>
 242         <varlistentry>
 243           <term><varname>DHCP=</varname></term>
 244           <listitem>
 245             <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
 246             <literal>yes</literal>, <literal>no</literal>,
 247             <literal>ipv4</literal>, or <literal>ipv6</literal>.</para>
 248
 249             <para>Note that DHCPv6 will by default be triggered by Router
 250             Advertisement, if that is enabled, regardless of this parameter.
 251             By enabling DHCPv6 support explicitly, the DHCPv6 client will
 252             be started regardless of the presence of routers on the link,
 253             or what flags the routers pass. See
 254             <literal>IPv6AcceptRA=</literal>.</para>
 255
 256             <para>Furthermore, note that by default the domain name
 257             specified through DHCP is not used for name resolution.
 258             See option <option>UseDomains=</option> below.</para>
 259
 260             <para>See the <literal>[DHCP]</literal> section below for further configuration options for the DHCP client
 261             support.</para>
 262           </listitem>
 263         </varlistentry>
 264         <varlistentry>
 265           <term><varname>DHCPServer=</varname></term>
 266           <listitem>
 267             <para>A boolean. Enables DHCPv4 server support. Defaults
 268             to <literal>no</literal>. Further settings for the DHCP
 269             server may be set in the <literal>[DHCPServer]</literal>
 270             section described below.</para>
 271           </listitem>
 272         </varlistentry>
 273         <varlistentry>
 274           <term><varname>LinkLocalAddressing=</varname></term>
 275           <listitem>
 276             <para>Enables link-local address autoconfiguration. Accepts
 277             <literal>yes</literal>, <literal>no</literal>,
 278             <literal>ipv4</literal>, or <literal>ipv6</literal>. Defaults to
 279             <literal>ipv6</literal>.</para>
 280           </listitem>
 281         </varlistentry>
 282         <varlistentry>
 283           <term><varname>IPv4LLRoute=</varname></term>
 284           <listitem>
 285             <para>A boolean. When true, sets up the route needed for
 286             non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
 287             to false.
 288             </para>
 289           </listitem>
 290         </varlistentry>
 291         <varlistentry>
 292           <term><varname>IPv6Token=</varname></term>
 293           <listitem>
 294             <para>An IPv6 address with the top 64 bits unset. When set, indicates the
 295             64-bit interface part of SLAAC IPv6 addresses for this link. Note that
 296             the token is only ever used for SLAAC, and not for DHCPv6 addresses, even
 297             in the case DHCP is requested by router advertisement. By default, the
 298             token is autogenerated.</para>
 299           </listitem>
 300         </varlistentry>
 301         <varlistentry>
 302           <term><varname>LLMNR=</varname></term>
 303           <listitem>
 304             <para>A boolean or <literal>resolve</literal>. When true,
 305             enables <ulink
 306             url="https://tools.ietf.org/html/rfc4795">Link-Local
 307             Multicast Name Resolution</ulink> on the link. When set to
 308             <literal>resolve</literal>, only resolution is enabled,
 309             but not host registration and announcement. Defaults to
 310             true. This setting is read by
 311             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 312           </listitem>
 313         </varlistentry>
 314         <varlistentry>
 315           <term><varname>MulticastDNS=</varname></term>
 316           <listitem>
 317             <para>A boolean or <literal>resolve</literal>. When true,
 318             enables <ulink
 319             url="https://tools.ietf.org/html/rfc6762">Multicast
 320             DNS</ulink> support on the link. When set to
 321             <literal>resolve</literal>, only resolution is enabled,
 322             but not host or service registration and
 323             announcement. Defaults to false. This setting is read by
 324             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 325           </listitem>
 326         </varlistentry>
 327         <varlistentry>
 328           <term><varname>DNSSEC=</varname></term>
 329           <listitem>
 330             <para>A boolean or
 331             <literal>allow-downgrade</literal>. When true, enables
 332             <ulink
 333             url="https://tools.ietf.org/html/rfc4033">DNSSEC</ulink>
 334             DNS validation support on the link. When set to
 335             <literal>allow-downgrade</literal>, compatibility with
 336             non-DNSSEC capable networks is increased, by automatically
 337             turning off DNSEC in this case. This option defines a
 338             per-interface setting for
 339             <citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
 340             global <varname>DNSSEC=</varname> option. Defaults to
 341             false. This setting is read by
 342             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 343           </listitem>
 344         </varlistentry>
 345         <varlistentry>
 346           <term><varname>DNSSECNegativeTrustAnchors=</varname></term>
 347           <listitem><para>A space-separated list of DNSSEC negative
 348           trust anchor domains. If specified and DNSSEC is enabled,
 349           look-ups done via the interface's DNS server will be subject
 350           to the list of negative trust anchors, and not require
 351           authentication for the specified domains, or anything below
 352           it. Use this to disable DNSSEC authentication for specific
 353           private domains, that cannot be proven valid using the
 354           Internet DNS hierarchy. Defaults to the empty list. This
 355           setting is read by
 356           <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 357           </listitem>
 358         </varlistentry>
 359         <varlistentry>
 360           <term><varname>LLDP=</varname></term>
 361           <listitem>
 362             <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
 363             implemented on professional routers and bridges which announces which physical port a system is connected
 364             to, as well as other related data. Accepts a boolean or the special value
 365             <literal>routers-only</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
 366             neighbors maintained. If <literal>routers-only</literal> is set only LLDP data of various types of routers
 367             is collected and LLDP data about other types of devices ignored (such as stations, telephones and
 368             others). If false, LLDP reception is disabled. Defaults to <literal>routers-only</literal>. Use
 369             <citerefentry><refentrytitle>networkctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
 370             collected neighbor data. LLDP is only available on Ethernet links. See <varname>EmitLLDP=</varname> below
 371             for enabling LLDP packet emission from the local system.
 372             </para>
 373           </listitem>
 374         </varlistentry>
 375         <varlistentry>
 376           <term><varname>EmitLLDP=</varname></term>
 377           <listitem>
 378             <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
 379             <literal>nearest-bridge</literal>, <literal>non-tpmr-bridge</literal> and
 380             <literal>customer-bridge</literal>.  Defaults to false, which turns off LLDP packet emission. If not false,
 381             a short LLDP packet with information about the local system is sent out in regular intervals on the
 382             link. The LLDP packet will contain information about the local host name, the local machine ID (as stored
 383             in <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
 384             local interface name, as well as the pretty hostname of the system (as set in
 385             <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
 386             emission is only available on Ethernet links. Note that this setting passes data suitable for
 387             identification of host to the network and should thus not be enabled on untrusted networks, where such
 388             identification data should not be made available. Use this option to permit other systems to identify on
 389             which interfaces they are connected to this system. The three special values control propagation of the
 390             LLDP packets. The <literal>nearest-bridge</literal> setting permits propagation only to the nearest
 391             connected bridge, <literal>non-tpmr-bridge</literal> permits propagation across Two-Port MAC Relays, but
 392             not any other bridges, and <literal>customer-bridge</literal> permits propagation until a customer bridge
 393             is reached. For details about these concepts, see <ulink
 394             url="http://standards.ieee.org/getieee802/download/802.1AB-2009.pdf">IEEE 802.1AB-2009</ulink>. Note that
 395             configuring this setting to true is equivalent to <literal>nearest-bridge</literal>, the recommended and
 396             most restricted level of propagation. See <varname>LLDP=</varname> above for an option to enable LLDP
 397             reception.</para>
 398           </listitem>
 399         </varlistentry>
 400         <varlistentry>
 401           <term><varname>BindCarrier=</varname></term>
 402           <listitem>
 403             <para>A link name or a list of link names. When set, controls the behavior of the current
 404             link. When all links in the list are in an operational down state, the current link is brought
 405             down. When at least one link has carrier, the current interface is brought up.
 406             </para>
 407           </listitem>
 408         </varlistentry>
 409         <varlistentry>
 410           <term><varname>Address=</varname></term>
 411           <listitem>
 412             <para>A static IPv4 or IPv6 address and its prefix length,
 413             separated by a <literal>/</literal> character. Specify
 414             this key more than once to configure several addresses.
 415             The format of the address must be as described in
 416             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 417             This is a short-hand for an [Address] section only
 418             containing an Address key (see below). This option may be
 419             specified more than once.
 420             </para>
 421
 422             <para>If the specified address is 0.0.0.0 (for IPv4) or
 423             [::] (for IPv6), a new address range of the requested size
 424             is automatically allocated from a system-wide pool of
 425             unused ranges. The allocated range is checked against all
 426             current network interfaces and all known network
 427             configuration files to avoid address range conflicts. The
 428             default system-wide pool consists of 192.168.0.0/16,
 429             172.16.0.0/12 and 10.0.0.0/8 for IPv4, and fc00::/7 for
 430             IPv6. This functionality is useful to manage a large
 431             number of dynamically created network interfaces with the
 432             same network configuration and automatic address range
 433             assignment.</para>
 434
 435           </listitem>
 436         </varlistentry>
 437         <varlistentry>
 438           <term><varname>Gateway=</varname></term>
 439           <listitem>
 440             <para>The gateway address, which must be in the format
 441             described in
 442             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 443             This is a short-hand for a [Route] section only containing
 444             a Gateway key. This option may be specified more than
 445             once.</para>
 446           </listitem>
 447         </varlistentry>
 448         <varlistentry>
 449           <term><varname>DNS=</varname></term>
 450           <listitem>
 451             <para>A DNS server address, which must be in the format
 452             described in
 453             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 454             This option may be specified more than once. This setting is read by
 455             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 456           </listitem>
 457         </varlistentry>
 458         <varlistentry>
 459           <term><varname>Domains=</varname></term>
 460           <listitem>
 461             <para>The domains used for DNS host name resolution on this link. Takes a list of DNS domain names which
 462             are used as search suffixes for extending single-label host names (host names containing no dots) to become
 463             fully qualified domain names (FQDNs). If a single-label host name is resolved on this interface, each of
 464             the specified search domains are appended to it in turn, converting it into a fully qualified domain name,
 465             until one of them may be successfully resolved.</para>
 466
 467             <para>The specified domains are also used for routing of DNS queries: look-ups for host names ending in the
 468             domains specified here are preferably routed to the DNS servers configured for this interface. If a domain
 469             name is prefixed with <literal>~</literal>, the domain name becomes a pure "routing" domain, is used for
 470             DNS query routing purposes only and is not used in the described domain search logic. By specifying a
 471             routing domain of <literal>~.</literal> (the tilde indicating definition of a routing domain, the dot
 472             referring to the DNS root domain which is the implied suffix of all valid DNS names) it is possible to
 473             route all DNS traffic preferably to the DNS server specified for this interface. The route domain logic is
 474             particularly useful on multi-homed hosts with DNS servers serving particular private DNS zones on each
 475             interface.</para>
 476
 477             <para>This setting is read by
 478             <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 479           </listitem>
 480         </varlistentry>
 481         <varlistentry>
 482           <term><varname>NTP=</varname></term>
 483           <listitem>
 484             <para>An NTP server address. This option may be specified more than once. This setting is read by
 485             <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 486           </listitem>
 487         </varlistentry>
 488         <varlistentry>
 489           <term><varname>IPForward=</varname></term>
 490           <listitem><para>Configures IP packet forwarding for the
 491           system. If enabled, incoming packets on any network
 492           interface will be forwarded to any other interfaces
 493           according to the routing table. Takes either a boolean
 494           argument, or the values <literal>ipv4</literal> or
 495           <literal>ipv6</literal>, which only enable IP packet
 496           forwarding for the specified address family.  This controls
 497           the <filename>net.ipv4.ip_forward</filename> and
 498           <filename>net.ipv6.conf.all.forwarding</filename> sysctl
 499           options of the network interface (see <ulink
 500           url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink>
 501           for details about sysctl options). Defaults to
 502           <literal>no</literal>.</para>
 503
 504           <para>Note: this setting controls a global kernel option,
 505           and does so one way only: if a network that has this setting
 506           enabled is set up the global setting is turned on.  However,
 507           it is never turned off again, even after all networks with
 508           this setting enabled are shut down again.</para>
 509
 510           <para>To allow IP packet forwarding only between specific
 511           network interfaces use a firewall.</para>
 512           </listitem>
 513         </varlistentry>
 514         <varlistentry>
 515           <term><varname>IPMasquerade=</varname></term>
 516           <listitem><para>Configures IP masquerading for the network
 517           interface. If enabled, packets forwarded from the network
 518           interface will be appear as coming from the local host.
 519           Takes a boolean argument. Implies
 520           <varname>IPForward=ipv4</varname>. Defaults to
 521           <literal>no</literal>.</para></listitem>
 522         </varlistentry>
 523         <varlistentry>
 524           <term><varname>IPv6PrivacyExtensions=</varname></term>
 525           <listitem><para>Configures use of stateless temporary
 526           addresses that change over time (see <ulink
 527           url="https://tools.ietf.org/html/rfc4941">RFC 4941</ulink>,
 528           Privacy Extensions for Stateless Address Autoconfiguration
 529           in IPv6). Takes a boolean or the special values
 530           <literal>prefer-public</literal> and
 531           <literal>kernel</literal>. When true, enables the privacy
 532           extensions and prefers temporary addresses over public
 533           addresses. When <literal>prefer-public</literal>, enables the
 534           privacy extensions, but prefers public addresses over
 535           temporary addresses. When false, the privacy extensions
 536           remain disabled. When <literal>kernel</literal>, the kernel's
 537           default setting will be left in place.  Defaults to
 538           <literal>no</literal>.</para></listitem>
 539         </varlistentry>
 540         <varlistentry>
 541           <term><varname>IPv6AcceptRA=</varname></term>
 542           <listitem><para>Enable or disable IPv6 Router Advertisement (RA) reception support for the interface.  Takes
 543           a boolean parameter. If true, RAs are accepted; if false, RAs are ignored, independently of the local
 544           forwarding state. When not set, the kernel default is used, and RAs are accepted only when local forwarding
 545           is disabled for that interface.  When RAs are accepted, they may trigger the start of the DHCPv6 client if
 546           the relevant flags are set in the RA data, or if no routers are found on the link.</para>
 547
 548           <para>Further settings for the IPv6 RA support may be configured in the
 549           <literal>[IPv6AcceptRA]</literal> section, see below.</para>
 550
 551           <para>Also see <ulink
 552           url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink> in the kernel
 553           documentation regarding <literal>accept_ra</literal>, but note that systemd's setting of
 554           <constant>1</constant> (i.e. true) corresponds to kernel's setting of <constant>2</constant>.</para>
 555         </listitem>
 556         </varlistentry>
 557         <varlistentry>
 558           <term><varname>IPv6DuplicateAddressDetection=</varname></term>
 559           <listitem><para>Configures the amount of IPv6 Duplicate
 560           Address Detection (DAD) probes to send. Defaults to unset.
 561         </para></listitem>
 562         </varlistentry>
 563         <varlistentry>
 564           <term><varname>IPv6HopLimit=</varname></term>
 565           <listitem><para>Configures IPv6 Hop Limit. For each router that
 566           forwards the packet, the hop limit is decremented by 1. When the
 567           hop limit field reaches zero, the packet is discarded.
 568           Defaults to unset.
 569         </para></listitem>
 570         </varlistentry>
 571         <varlistentry>
 572           <term><varname>ProxyARP=</varname></term>
 573           <listitem><para>A boolean. Configures proxy ARP. Proxy ARP is the technique in which one host,
 574           usually a router, answers ARP requests intended for another machine. By "faking" its identity,
 575           the router accepts responsibility for routing packets to the "real" destination. (see <ulink
 576           url="https://tools.ietf.org/html/rfc1027">RFC 1027</ulink>.
 577           Defaults to unset.
 578         </para></listitem>
 579         </varlistentry>
 580         <varlistentry>
 581           <term><varname>Bridge=</varname></term>
 582           <listitem>
 583             <para>The name of the bridge to add the link to.</para>
 584           </listitem>
 585         </varlistentry>
 586         <varlistentry>
 587           <term><varname>Bond=</varname></term>
 588           <listitem>
 589             <para>The name of the bond to add the link to.</para>
 590           </listitem>
 591         </varlistentry>
 592         <varlistentry>
 593           <term><varname>VRF=</varname></term>
 594           <listitem>
 595             <para>The name of the VRF to add the link to.</para>
 596           </listitem>
 597         </varlistentry>
 598         <varlistentry>
 599           <term><varname>VLAN=</varname></term>
 600           <listitem>
 601             <para>The name of a VLAN to create on the link. This
 602             option may be specified more than once.</para>
 603           </listitem>
 604         </varlistentry>
 605         <varlistentry>
 606           <term><varname>MACVLAN=</varname></term>
 607           <listitem>
 608             <para>The name of a MACVLAN to create on the link. This
 609             option may be specified more than once.</para>
 610           </listitem>
 611         </varlistentry>
 612         <varlistentry>
 613           <term><varname>VXLAN=</varname></term>
 614           <listitem>
 615             <para>The name of a VXLAN to create on the link. This
 616             option may be specified more than once.</para>
 617           </listitem>
 618         </varlistentry>
 619         <varlistentry>
 620           <term><varname>Tunnel=</varname></term>
 621           <listitem>
 622             <para>The name of a Tunnel to create on the link. This
 623             option may be specified more than once.</para>
 624           </listitem>
 625         </varlistentry>
 626       </variablelist>
 627
 628   </refsect1>
 629
 630   <refsect1>
 631     <title>[Address] Section Options</title>
 632
 633       <para>An <literal>[Address]</literal> section accepts the
 634       following keys. Specify several <literal>[Address]</literal>
 635       sections to configure several addresses.</para>
 636
 637       <variablelist class='network-directives'>
 638         <varlistentry>
 639           <term><varname>Address=</varname></term>
 640           <listitem>
 641             <para>As in the <literal>[Network]</literal> section. This
 642             key is mandatory.</para>
 643           </listitem>
 644         </varlistentry>
 645         <varlistentry>
 646           <term><varname>Peer=</varname></term>
 647           <listitem>
 648             <para>The peer address in a point-to-point connection.
 649             Accepts the same format as the <literal>Address</literal>
 650             key.</para>
 651           </listitem>
 652         </varlistentry>
 653         <varlistentry>
 654           <term><varname>Broadcast=</varname></term>
 655           <listitem>
 656             <para>The broadcast address, which must be in the format
 657             described in
 658             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
 659             This key only applies to IPv4 addresses. If it is not
 660             given, it is derived from the <literal>Address</literal>
 661             key.</para>
 662           </listitem>
 663         </varlistentry>
 664         <varlistentry>
 665           <term><varname>Label=</varname></term>
 666           <listitem>
 667             <para>An address label.</para>
 668           </listitem>
 669         </varlistentry>
 670         <varlistentry>
 671           <term><varname>PreferredLifetime=</varname></term>
 672           <listitem>
 673             <para>Allows the default "preferred lifetime" of the address to be overridden.
 674             Only three settings are accepted: <literal>forever</literal> or <literal>infinity</literal>
 675             which is the default and means that the address never expires, and <literal>0</literal> which means
 676             that the address is considered immediately "expired" and will not be used,
 677             unless explicitly requested. A setting of PreferredLifetime=0 is useful for
 678             addresses which are added to be used only by a specific application,
 679             which is then configured to use them explicitly.</para>
 680           </listitem>
 681         </varlistentry>
 682       </variablelist>
 683   </refsect1>
 684
 685   <refsect1>
 686     <title>[Route] Section Options</title>
 687       <para>The <literal>[Route]</literal> section accepts the
 688       following keys. Specify several <literal>[Route]</literal>
 689       sections to configure several routes.</para>
 690
 691       <variablelist class='network-directives'>
 692         <varlistentry>
 693           <term><varname>Gateway=</varname></term>
 694           <listitem>
 695             <para>As in the <literal>[Network]</literal> section.</para>
 696           </listitem>
 697         </varlistentry>
 698         <varlistentry>
 699           <term><varname>Destination=</varname></term>
 700           <listitem>
 701             <para>The destination prefix of the route. Possibly
 702             followed by a slash and the prefix length. If omitted, a
 703             full-length host route is assumed.</para>
 704           </listitem>
 705         </varlistentry>
 706         <varlistentry>
 707           <term><varname>Source=</varname></term>
 708           <listitem>
 709             <para>The source prefix of the route. Possibly followed by
 710             a slash and the prefix length. If omitted, a full-length
 711             host route is assumed.</para>
 712           </listitem>
 713         </varlistentry>
 714         <varlistentry>
 715           <term><varname>Metric=</varname></term>
 716           <listitem>
 717             <para>The metric of the route (an unsigned integer).</para>
 718           </listitem>
 719         </varlistentry>
 720         <varlistentry>
 721           <term><varname>Scope=</varname></term>
 722           <listitem>
 723             <para>The scope of the route, which can be <literal>global</literal>,
 724             <literal>link</literal> or <literal>host</literal>. Defaults to
 725             <literal>global</literal>.</para>
 726           </listitem>
 727         </varlistentry>
 728         <varlistentry>
 729           <term><varname>PreferredSource=</varname></term>
 730           <listitem>
 731             <para>The preferred source address of the route. The address
 732             must be in the format described in
 733             <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
 734           </listitem>
 735         </varlistentry>
 736         <varlistentry>
 737           <term><varname>Table=<replaceable>num</replaceable></varname></term>
 738           <listitem>
 739           <para>The table identifier for the route (a number between 1 and 4294967295, or 0 to unset).
 740           The table can be retrieved using <command>ip route show table <replaceable>num</replaceable></command>.
 741           </para>
 742           </listitem>
 743         </varlistentry>
 744       </variablelist>
 745   </refsect1>
 746
 747   <refsect1>
 748     <title>[DHCP] Section Options</title>
 749       <para>The <literal>[DHCP]</literal> section configures the
 750       DHCPv4 and DHCP6 client, if it is enabled with the
 751       <varname>DHCP=</varname> setting described above:</para>
 752
 753       <variablelist class='network-directives'>
 754         <varlistentry>
 755           <term><varname>UseDNS=</varname></term>
 756           <listitem>
 757             <para>When true (the default), the DNS servers received
 758             from the DHCP server will be used and take precedence over
 759             any statically configured ones.</para>
 760
 761             <para>This corresponds to the <option>nameserver</option>
 762             option in <citerefentry
 763             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 764           </listitem>
 765         </varlistentry>
 766         <varlistentry>
 767           <term><varname>UseNTP=</varname></term>
 768           <listitem>
 769             <para>When true (the default), the NTP servers received
 770             from the DHCP server will be used by systemd-timesyncd
 771             and take precedence over any statically configured ones.</para>
 772           </listitem>
 773         </varlistentry>
 774         <varlistentry>
 775           <term><varname>UseMTU=</varname></term>
 776           <listitem>
 777             <para>When true, the interface maximum transmission unit
 778             from the DHCP server will be used on the current link.
 779             Defaults to false.</para>
 780           </listitem>
 781         </varlistentry>
 782         <varlistentry>
 783           <term><varname>SendHostname=</varname></term>
 784           <listitem>
 785             <para>When true (the default), the machine's hostname will
 786             be sent to the DHCP server.</para>
 787           </listitem>
 788         </varlistentry>
 789         <varlistentry>
 790           <term><varname>UseHostname=</varname></term>
 791           <listitem>
 792             <para>When true (the default), the hostname received from
 793             the DHCP server will be set as the transient hostname of the system
 794             </para>
 795           </listitem>
 796         </varlistentry>
 797         <varlistentry>
 798         <term><varname>Hostname=</varname></term>
 799         <listitem>
 800           <para>Use this value for the hostname which is sent to the
 801           DHCP server, instead of machine's hostname.</para>
 802         </listitem>
 803       </varlistentry>
 804         <varlistentry>
 805           <term><varname>UseDomains=</varname></term>
 806           <listitem>
 807             <para>Takes a boolean argument, or the special value <literal>route</literal>. When true, the domain name
 808             received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
 809             the <option>Domains=</option> setting. If set to <literal>route</literal>, the domain name received from
 810             the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
 811             the <option>Domains=</option> setting when the argument is prefixed with <literal>~</literal>. Defaults to
 812             false.</para>
 813
 814             <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
 815             of all host names, in particular of single-label names. It is generally safer to use the supplied domain
 816             only as routing domain, rather than as search domain, in order to not have it affect local resolution of
 817             single-label names.</para>
 818
 819             <para>When set to true, this setting corresponds to the <option>domain</option> option in <citerefentry
 820             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 821           </listitem>
 822         </varlistentry>
 823         <varlistentry>
 824           <term><varname>UseRoutes=</varname></term>
 825           <listitem>
 826             <para>When true (the default), the static routes will be
 827             requested from the DHCP server and added to the routing
 828             table with a metric of 1024.</para>
 829           </listitem>
 830         </varlistentry>
 831
 832         <varlistentry>
 833           <term><varname>UseTimezone=</varname></term>
 834
 835           <listitem><para>When true, the timezone received from the
 836           DHCP server will be set as timezone of the local
 837           system. Defaults to <literal>no</literal>.</para></listitem>
 838         </varlistentry>
 839
 840         <varlistentry>
 841           <term><varname>CriticalConnection=</varname></term>
 842           <listitem>
 843             <para>When true, the connection will never be torn down
 844             even if the DHCP lease expires. This is contrary to the
 845             DHCP specification, but may be the best choice if, say,
 846             the root filesystem relies on this connection. Defaults to
 847             false.</para>
 848           </listitem>
 849         </varlistentry>
 850
 851         <varlistentry>
 852           <term><varname>ClientIdentifier=</varname></term>
 853           <listitem>
 854             <para>The DHCPv4 client identifier to use. Either <literal>mac</literal> to use the MAC address of the link
 855             or <literal>duid</literal> (the default, see below) to use an RFC4361-compliant Client ID.</para>
 856           </listitem>
 857         </varlistentry>
 858
 859         <varlistentry>
 860           <term><varname>VendorClassIdentifier=</varname></term>
 861           <listitem>
 862             <para>The vendor class identifier used to identify vendor
 863             type and configuration.</para>
 864           </listitem>
 865         </varlistentry>
 866
 867         <varlistentry>
 868           <term><varname>DUIDType=</varname></term>
 869           <listitem>
 870             <para>Override the global <varname>DUIDType</varname> setting for this network. See
 871             <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 872             for a description of possible values.</para>
 873           </listitem>
 874         </varlistentry>
 875
 876         <varlistentry>
 877           <term><varname>DUIDRawData=</varname></term>
 878           <listitem>
 879             <para>Override the global <varname>DUIDRawData</varname> setting for this network. See
 880             <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 881             for a description of possible values.</para>
 882           </listitem>
 883         </varlistentry>
 884
 885         <varlistentry>
 886           <term><varname>IAID=</varname></term>
 887           <listitem>
 888             <para>The DHCP Identity Association Identifier (IAID) for the interface, a 32-bit unsigned integer.</para>
 889           </listitem>
 890         </varlistentry>
 891
 892         <varlistentry>
 893           <term><varname>RequestBroadcast=</varname></term>
 894           <listitem>
 895             <para>Request the server to use broadcast messages before
 896             the IP address has been configured. This is necessary for
 897             devices that cannot receive RAW packets, or that cannot
 898             receive packets at all before an IP address has been
 899             configured. On the other hand, this must not be enabled on
 900             networks where broadcasts are filtered out.</para>
 901           </listitem>
 902         </varlistentry>
 903
 904         <varlistentry>
 905           <term><varname>RouteMetric=</varname></term>
 906           <listitem>
 907             <para>Set the routing metric for routes specified by the
 908             DHCP server.</para>
 909           </listitem>
 910         </varlistentry>
 911       </variablelist>
 912     </refsect1>
 913
 914   <refsect1>
 915     <title>[IPv6AcceptRA] Section Options</title>
 916       <para>The <literal>[IPv6AcceptRA]</literal> section configures the IPv6 Router Advertisement
 917       (RA) client, if it is enabled with the <varname>IPv6AcceptRA=</varname> setting described
 918       above:</para>
 919
 920       <variablelist class='network-directives'>
 921         <varlistentry>
 922           <term><varname>UseDNS=</varname></term>
 923           <listitem>
 924             <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
 925             precedence over any statically configured ones.</para>
 926
 927             <para>This corresponds to the <option>nameserver</option> option in <citerefentry
 928             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 929           </listitem>
 930         </varlistentry>
 931
 932         <varlistentry>
 933           <term><varname>UseDomains=</varname></term>
 934           <listitem>
 935             <para>Takes a boolean argument, or the special value <literal>route</literal>. When true, the domain name
 936             received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
 937             the effect of the <option>Domains=</option> setting. If set to <literal>route</literal>, the domain name
 938             received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
 939             effect of the <option>Domains=</option> setting when the argument is prefixed with
 940             <literal>~</literal>. Defaults to false.</para>
 941
 942             <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
 943             of all host names, in particular of single-label names. It is generally safer to use the supplied domain
 944             only as routing domain, rather than as search domain, in order to not have it affect local resolution of
 945             single-label names.</para>
 946
 947             <para>When set to true, this setting corresponds to the <option>domain</option> option in <citerefentry
 948             project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 949           </listitem>
 950         </varlistentry>
 951       </variablelist>
 952   </refsect1>
 953
 954
 955   <refsect1>
 956     <title>[DHCPServer] Section Options</title>
 957     <para>The <literal>[DHCPServer]</literal> section contains
 958     settings for the DHCP server, if enabled via the
 959     <varname>DHCPServer=</varname> option described above:</para>
 960
 961     <variablelist class='network-directives'>
 962
 963       <varlistentry>
 964         <term><varname>PoolOffset=</varname></term>
 965         <term><varname>PoolSize=</varname></term>
 966
 967         <listitem><para>Configures the pool of addresses to hand out. The pool
 968         is a contiguous sequence of IP addresses in the subnet configured for
 969         the server address, which does not include the subnet nor the broadcast
 970         address. <varname>PoolOffset=</varname> takes the offset of the pool
 971         from the start of subnet, or zero to use the default value.
 972         <varname>PoolSize=</varname> takes the number of IP addresses in the
 973         pool or zero to use the default value. By default, the pool starts at
 974         the first address after the subnet address and takes up the rest of
 975         the subnet, excluding the broadcast address. If the pool includes
 976         the server address (the default), this is reserved and not handed
 977         out to clients.</para></listitem>
 978       </varlistentry>
 979
 980       <varlistentry>
 981         <term><varname>DefaultLeaseTimeSec=</varname></term>
 982         <term><varname>MaxLeaseTimeSec=</varname></term>
 983
 984         <listitem><para>Control the default and maximum DHCP lease
 985         time to pass to clients. These settings take time values in seconds or
 986         another common time unit, depending on the suffix. The default
 987         lease time is used for clients that did not ask for a specific
 988         lease time. If a client asks for a lease time longer than the
 989         maximum lease time, it is automatically shortened to the
 990         specified time. The default lease time defaults to 1h, the
 991         maximum lease time to 12h. Shorter lease times are beneficial
 992         if the configuration data in DHCP leases changes frequently
 993         and clients shall learn the new settings with shorter
 994         latencies. Longer lease times reduce the generated DHCP
 995         network traffic.</para></listitem>
 996       </varlistentry>
 997
 998       <varlistentry>
 999         <term><varname>EmitDNS=</varname></term>
1000         <term><varname>DNS=</varname></term>
1001
1002         <listitem><para>Configures whether the DHCP leases handed out
1003         to clients shall contain DNS server information. The
1004         <varname>EmitDNS=</varname> setting takes a boolean argument
1005         and defaults to <literal>yes</literal>. The DNS servers to
1006         pass to clients may be configured with the
1007         <varname>DNS=</varname> option, which takes a list of IPv4
1008         addresses. If the <varname>EmitDNS=</varname> option is
1009         enabled but no servers configured, the servers are
1010         automatically propagated from an "uplink" interface that has
1011         appropriate servers set. The "uplink" interface is determined
1012         by the default route of the system with the highest
1013         priority. Note that this information is acquired at the time
1014         the lease is handed out, and does not take uplink interfaces
1015         into account that acquire DNS or NTP server information at a
1016         later point. DNS server propagation does not take
1017         <filename>/etc/resolv.conf</filename> into account. Also, note
1018         that the leases are not refreshed if the uplink network
1019         configuration changes. To ensure clients regularly acquire the
1020         most current uplink DNS server information, it is thus
1021         advisable to shorten the DHCP lease time via
1022         <varname>MaxLeaseTimeSec=</varname> described
1023         above.</para></listitem>
1024       </varlistentry>
1025
1026       <varlistentry>
1027         <term><varname>EmitNTP=</varname></term>
1028         <term><varname>NTP=</varname></term>
1029
1030         <listitem><para>Similar to the <varname>EmitDNS=</varname> and
1031         <varname>DNS=</varname> settings described above, these
1032         settings configure whether and what NTP server information
1033         shall be emitted as part of the DHCP lease. The same syntax,
1034         propagation semantics and defaults apply as for
1035         <varname>EmitDNS=</varname> and
1036         <varname>DNS=</varname>.</para></listitem>
1037       </varlistentry>
1038
1039       <varlistentry>
1040         <term><varname>EmitRouter=</varname></term>
1041
1042         <listitem><para>Similar to the <varname>EmitDNS=</varname>
1043         setting described above, this setting configures whether the
1044         DHCP lease should contain the router option. The same syntax,
1045         propagation semantics and defaults apply as for
1046         <varname>EmitDNS=</varname>.</para></listitem>
1047       </varlistentry>
1048
1049       <varlistentry>
1050         <term><varname>EmitTimezone=</varname></term>
1051         <term><varname>Timezone=</varname></term>
1052
1053         <listitem><para>Configures whether the DHCP leases handed out
1054         to clients shall contain timezone information. The
1055         <varname>EmitTimezone=</varname> setting takes a boolean
1056         argument and defaults to <literal>yes</literal>. The
1057         <varname>Timezone=</varname> setting takes a timezone string
1058         (such as <literal>Europe/Berlin</literal> or
1059         <literal>UTC</literal>) to pass to clients. If no explicit
1060         timezone is set, the system timezone of the local host is
1061         propagated, as determined by the
1062         <filename>/etc/localtime</filename> symlink.</para></listitem>
1063       </varlistentry>
1064
1065     </variablelist>
1066   </refsect1>
1067
1068   <refsect1>
1069     <title>[Bridge] Section Options</title>
1070       <para>The <literal>[Bridge]</literal> section accepts the
1071       following keys.</para>
1072       <variablelist class='network-directives'>
1073         <varlistentry>
1074           <term><varname>UnicastFlood=</varname></term>
1075           <listitem>
1076             <para>A boolean. Controls whether the bridge should flood
1077             traffic for which an FDB entry is missing and the destination
1078             is unknown through this port. Defaults to on.
1079             </para>
1080           </listitem>
1081         </varlistentry>
1082         <varlistentry>
1083           <term><varname>HairPin=</varname></term>
1084           <listitem>
1085             <para>A boolean. Configures whether traffic may be sent back
1086             out of the port on which it was received. By default, this
1087             flag is false, and the bridge will not forward traffic back
1088             out of the receiving port.</para>
1089           </listitem>
1090         </varlistentry>
1091         <varlistentry>
1092           <term><varname>UseBPDU=</varname></term>
1093           <listitem>
1094             <para>A boolean. Configures whether STP Bridge Protocol Data Units will be
1095             processed by the bridge port. Defaults to yes.</para>
1096           </listitem>
1097         </varlistentry>
1098         <varlistentry>
1099           <term><varname>FastLeave=</varname></term>
1100           <listitem>
1101             <para>A boolean. This flag allows the bridge to immediately stop multicast
1102             traffic on a port that receives an IGMP Leave message. It is only used with
1103             IGMP snooping if enabled on the bridge. Defaults to off.</para>
1104           </listitem>
1105         </varlistentry>
1106         <varlistentry>
1107           <term><varname>AllowPortToBeRoot=</varname></term>
1108           <listitem>
1109             <para>A boolean. Configures whether a given port is allowed to
1110             become a root port. Only used when STP is enabled on the bridge.
1111             Defaults to on.</para>
1112           </listitem>
1113         </varlistentry>
1114         <varlistentry>
1115           <term><varname>Cost=</varname></term>
1116           <listitem>
1117             <para>Sets the "cost" of sending packets of this interface.
1118             Each port in a bridge may have a different speed and the cost
1119             is used to decide which link to use. Faster interfaces
1120             should have lower costs.</para>
1121           </listitem>
1122         </varlistentry>
1123       </variablelist>
1124   </refsect1>
1125   <refsect1>
1126     <title>[BridgeFDB] Section Options</title>
1127       <para>The <literal>[BridgeFDB]</literal> section manages the
1128       forwarding database table of a port and accepts the following
1129       keys. Specify several <literal>[BridgeFDB]</literal> sections to
1130       configure several static MAC table entries.</para>
1131
1132       <variablelist class='network-directives'>
1133         <varlistentry>
1134           <term><varname>MACAddress=</varname></term>
1135           <listitem>
1136             <para>As in the <literal>[Network]</literal> section. This
1137             key is mandatory.</para>
1138           </listitem>
1139         </varlistentry>
1140         <varlistentry>
1141           <term><varname>VLANId=</varname></term>
1142           <listitem>
1143             <para>The VLAN ID for the new static MAC table entry. If
1144             omitted, no VLAN ID info is appended to the new static MAC
1145             table entry.</para>
1146           </listitem>
1147         </varlistentry>
1148       </variablelist>
1149   </refsect1>
1150   <refsect1>
1151     <title>[BridgeVLAN] Section Options</title>
1152       <para>The <literal>[BridgeVLAN]</literal> section manages the VLAN ID configuration of a bridge port and accepts
1153       the following keys. Specify several <literal>[BridgeVLAN]</literal> sections to configure several VLAN entries.
1154       The <varname>VLANFiltering=</varname> option has to be enabled, see <literal>[Bridge]</literal> section in
1155       <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
1156
1157       <variablelist class='network-directives'>
1158         <varlistentry>
1159           <term><varname>VLAN=</varname></term>
1160           <listitem>
1161             <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
1162             from 1 to 4094.</para>
1163           </listitem>
1164         </varlistentry>
1165         <varlistentry>
1166           <term><varname>EgressUntagged=</varname></term>
1167           <listitem>
1168             <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
1169             <varname>EgressUntagged=</varname> implicates the use of <varname>VLAN=</varname> above and will enable the
1170             VLAN ID for ingress as well. This can be either a single ID or a range M-N.</para>
1171           </listitem>
1172         </varlistentry>
1173         <varlistentry>
1174           <term><varname>PVID=</varname></term>
1175           <listitem>
1176             <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
1177             <varname>PVID=</varname> can be used only once. Configuring <varname>PVID=</varname> implicates the use of
1178             <varname>VLAN=</varname> above and will enable the VLAN ID for ingress as well.</para>
1179           </listitem>
1180         </varlistentry>
1181       </variablelist>
1182   </refsect1>
1183
1184   <refsect1>
1185     <title>Example</title>
1186     <example>
1187       <title>/etc/systemd/network/50-static.network</title>
1188
1189       <programlisting>[Match]
1190 Name=enp2s0
1191
1192 [Network]
1193 Address=192.168.0.15/24
1194 Gateway=192.168.0.1</programlisting>
1195     </example>
1196
1197     <example>
1198       <title>/etc/systemd/network/80-dhcp.network</title>
1199
1200       <programlisting>[Match]
1201 Name=en*
1202
1203 [Network]
1204 DHCP=yes</programlisting>
1205     </example>
1206
1207     <example>
1208       <title>/etc/systemd/network/25-bridge-static.network</title>
1209
1210       <programlisting>[Match]
1211 Name=bridge0
1212
1213 [Network]
1214 Address=192.168.0.15/24
1215 Gateway=192.168.0.1
1216 DNS=192.168.0.1</programlisting>
1217     </example>
1218
1219     <example>
1220       <title>/etc/systemd/network/25-bridge-slave-interface.network</title>
1221
1222       <programlisting>[Match]
1223 Name=enp2s0
1224
1225 [Network]
1226 Bridge=bridge0</programlisting>
1227     </example>
1228     <example>
1229       <title>/etc/systemd/network/25-bridge-slave-interface-vlan.network</title>
1230
1231       <programlisting>[Match]
1232 Name=enp2s0
1233
1234 [Network]
1235 Bridge=bridge0
1236
1237 [BridgeVLAN]
1238 VLAN=1-32
1239 PVID=42
1240 EgressUntagged=42
1241
1242 [BridgeVLAN]
1243 VLAN=100-200
1244
1245 [BridgeVLAN]
1246 EgressUntagged=300-400</programlisting>
1247     </example>
1248     <example>
1249       <title>/etc/systemd/network/25-ipip.network</title>
1250
1251       <programlisting>[Match]
1252 Name=em1
1253
1254 [Network]
1255 Tunnel=ipip-tun</programlisting>
1256     </example>
1257
1258     <example>
1259       <title>/etc/systemd/network/25-sit.network</title>
1260
1261       <programlisting>[Match]
1262 Name=em1
1263
1264 [Network]
1265 Tunnel=sit-tun</programlisting>
1266     </example>
1267
1268     <example>
1269       <title>/etc/systemd/network/25-gre.network</title>
1270
1271       <programlisting>[Match]
1272 Name=em1
1273
1274 [Network]
1275 Tunnel=gre-tun</programlisting>
1276     </example>
1277
1278     <example>
1279       <title>/etc/systemd/network/25-vti.network</title>
1280
1281       <programlisting>[Match]
1282 Name=em1
1283
1284 [Network]
1285 Tunnel=vti-tun</programlisting>
1286     </example>
1287
1288     <example>
1289       <title>/etc/systemd/network/25-bond.network</title>
1290
1291       <programlisting>[Match]
1292 Name=bond1
1293
1294 [Network]
1295 DHCP=yes
1296 </programlisting>
1297     </example>
1298
1299     <example>
1300       <title>/etc/systemd/network/25-vrf.network</title>
1301       <para>Add the bond1 interface to the VRF master interface vrf-test. This will redirect routes generated on this interface to be within the routing table defined during VRF creation. Traffic won't be redirected towards the VRFs routing table unless specific ip-rules are added.</para>
1302       <programlisting>[Match]
1303 Name=bond1
1304
1305 [Network]
1306 VRF=vrf-test
1307 </programlisting>
1308     </example>
1309
1310   </refsect1>
1311
1312   <refsect1>
1313     <title>See Also</title>
1314     <para>
1315       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1316       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1317       <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1318       <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1319       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1320     </para>
1321   </refsect1>
1322
1323 </refentry>