NAME | SYNOPSIS | DESCRIPTION | [MATCH] SECTION OPTIONS | [LINK] SECTION OPTIONS | [NETWORK] SECTION OPTIONS | [ADDRESS] SECTION OPTIONS | [ROUTE] SECTION OPTIONS | [DHCP] SECTION OPTIONS | [IPV6ACCEPTRA] SECTION OPTIONS | [DHCPSERVER] SECTION OPTIONS | [BRIDGE] SECTION OPTIONS | [BRIDGEFDB] SECTION OPTIONS | [BRIDGEVLAN] SECTION OPTIONS | EXAMPLE | SEE ALSO | NOTES | COLOPHON

SYSTEMD.NETWORK(5)             systemd.network            SYSTEMD.NETWORK(5)

NAME         top

       systemd.network - Network configuration

SYNOPSIS         top

       network.network

DESCRIPTION         top

       Network setup is performed by systemd-networkd(8).

       The main network file must have the extension .network; other
       extensions are ignored. Networks are applied to links whenever the
       links appear.

       The .network files are read from the files located in the system
       network directory /usr/lib/systemd/network, the volatile runtime
       network directory /run/systemd/network and the local administration
       network directory /etc/systemd/network. All configuration files are
       collectively sorted and processed in lexical order, regardless of the
       directories in which they live. However, files with identical
       filenames replace each other. Files in /etc have the highest
       priority, files in /run take precedence over files with the same name
       in /usr/lib. This can be used to override a system-supplied
       configuration file with a local file if needed. As a special case, an
       empty file (file size 0) or symlink with the same name pointing to
       /dev/null disables the configuration file entirely (it is "masked").

       Along with the network file foo.network, a "drop-in" directory
       foo.network.d/ may exist. All files with the suffix ".conf" from this
       directory will be parsed after the file itself is parsed. This is
       useful to alter or add configuration settings, without having to
       modify the main configuration file. Each drop-in file must have
       appropriate section headers.

       In addition to /etc/systemd/network, drop-in ".d" directories can be
       placed in /usr/lib/systemd/network or /run/systemd/network
       directories. Drop-in files in /etc take precedence over those in /run
       which in turn take precedence over those in /usr/lib. Drop-in files
       under any of these directories take precedence over the main netdev
       file wherever located. (Of course, since /run is temporary and
       /usr/lib is for vendors, it is unlikely drop-ins should be used in
       either of those places.)

       Note that an interface without any static IPv6 addresses configured,
       and neither DHCPv6 nor IPv6LL enabled, shall be considered to have no
       IPv6 support. IPv6 will be automatically disabled for that interface
       by writing "1" to /proc/sys/net/ipv6/conf/ifname/disable_ipv6.

[MATCH] SECTION OPTIONS         top

       The network file contains a "[Match]" section, which determines if a
       given network file may be applied to a given device; and a
       "[Network]" section specifying how the device should be configured.
       The first (in lexical order) of the network files that matches a
       given device is applied, all later files are ignored, even if they
       match as well.

       A network file is said to match a device if each of the entries in
       the "[Match]" section matches, or if the section is empty. The
       following keys are accepted:

       MACAddress=
           The hardware address of the interface (use full colon-delimited
           hexadecimal, e.g., 01:23:45:67:89:ab).

       Path=
           A whitespace-separated list of shell-style globs matching the
           persistent path, as exposed by the udev property "ID_PATH".

       Driver=
           A whitespace-separated list of shell-style globs matching the
           driver currently bound to the device, as exposed by the udev
           property "DRIVER" of its parent device, or if that is not set the
           driver as exposed by "ethtool -i" of the device itself.

       Type=
           A whitespace-separated list of shell-style globs matching the
           device type, as exposed by the udev property "DEVTYPE".

       Name=
           A whitespace-separated list of shell-style globs matching the
           device name, as exposed by the udev property "INTERFACE".

       Host=
           Matches against the hostname or machine ID of the host. See
           "ConditionHost=" in systemd.unit(5) for details.

       Virtualization=
           Checks whether the system is executed in a virtualized
           environment and optionally test whether it is a specific
           implementation. See "ConditionVirtualization=" in systemd.unit(5)
           for details.

       KernelCommandLine=
           Checks whether a specific kernel command line option is set (or
           if prefixed with the exclamation mark unset). See
           "ConditionKernelCommandLine=" in systemd.unit(5) for details.

       Architecture=
           Checks whether the system is running on a specific architecture.
           See "ConditionArchitecture=" in systemd.unit(5) for details.

[LINK] SECTION OPTIONS         top

       The "[Link]" section accepts the following keys:

       MACAddress=
           The hardware address to set for the device.

       MTUBytes=
           The maximum transmission unit in bytes to set for the device. The
           usual suffixes K, M, G, are supported and are understood to the
           base of 1024.

           Note that if IPv6 is enabled on the interface, and the MTU is
           chosen below 1280 (the minimum MTU for IPv6) it will
           automatically be increased to this value.

       ARP=
           A boolean. Enables or disables the ARP (low-level Address
           Resolution Protocol) for this interface. Defaults to unset, which
           means that the kernel default will be used.

           For example, disabling ARP is useful when creating multiple
           MACVLAN or VLAN virtual interfaces atop a single lower-level
           physical interface, which will then only serve as a link/"bridge"
           device aggregating traffic to the same physical link and not
           participate in the network otherwise.

[NETWORK] SECTION OPTIONS         top

       The "[Network]" section accepts the following keys:

       Description=
           A description of the device. This is only used for presentation
           purposes.

       DHCP=
           Enables DHCPv4 and/or DHCPv6 client support. Accepts "yes", "no",
           "ipv4", or "ipv6".

           Note that DHCPv6 will by default be triggered by Router
           Advertisement, if that is enabled, regardless of this parameter.
           By enabling DHCPv6 support explicitly, the DHCPv6 client will be
           started regardless of the presence of routers on the link, or
           what flags the routers pass. See "IPv6AcceptRA=".

           Furthermore, note that by default the domain name specified
           through DHCP is not used for name resolution. See option
           UseDomains= below.

           See the "[DHCP]" section below for further configuration options
           for the DHCP client support.

       DHCPServer=
           A boolean. Enables DHCPv4 server support. Defaults to "no".
           Further settings for the DHCP server may be set in the
           "[DHCPServer]" section described below.

       LinkLocalAddressing=
           Enables link-local address autoconfiguration. Accepts "yes",
           "no", "ipv4", or "ipv6". Defaults to "ipv6".

       IPv4LLRoute=
           A boolean. When true, sets up the route needed for non-IPv4LL
           hosts to communicate with IPv4LL-only hosts. Defaults to false.

       IPv6Token=
           An IPv6 address with the top 64 bits unset. When set, indicates
           the 64-bit interface part of SLAAC IPv6 addresses for this link.
           Note that the token is only ever used for SLAAC, and not for
           DHCPv6 addresses, even in the case DHCP is requested by router
           advertisement. By default, the token is autogenerated.

       LLMNR=
           A boolean or "resolve". When true, enables Link-Local Multicast
           Name Resolution[1] on the link. When set to "resolve", only
           resolution is enabled, but not host registration and
           announcement. Defaults to true. This setting is read by
           systemd-resolved.service(8).

       MulticastDNS=
           A boolean or "resolve". When true, enables Multicast DNS[2]
           support on the link. When set to "resolve", only resolution is
           enabled, but not host or service registration and announcement.
           Defaults to false. This setting is read by
           systemd-resolved.service(8).

       DNSSEC=
           A boolean or "allow-downgrade". When true, enables DNSSEC[3] DNS
           validation support on the link. When set to "allow-downgrade",
           compatibility with non-DNSSEC capable networks is increased, by
           automatically turning off DNSEC in this case. This option defines
           a per-interface setting for resolved.conf(5)'s global DNSSEC=
           option. Defaults to false. This setting is read by
           systemd-resolved.service(8).

       DNSSECNegativeTrustAnchors=
           A space-separated list of DNSSEC negative trust anchor domains.
           If specified and DNSSEC is enabled, look-ups done via the
           interface's DNS server will be subject to the list of negative
           trust anchors, and not require authentication for the specified
           domains, or anything below it. Use this to disable DNSSEC
           authentication for specific private domains, that cannot be
           proven valid using the Internet DNS hierarchy. Defaults to the
           empty list. This setting is read by systemd-resolved.service(8).

       LLDP=
           Controls support for Ethernet LLDP packet reception. LLDP is a
           link-layer protocol commonly implemented on professional routers
           and bridges which announces which physical port a system is
           connected to, as well as other related data. Accepts a boolean or
           the special value "routers-only". When true, incoming LLDP
           packets are accepted and a database of all LLDP neighbors
           maintained. If "routers-only" is set only LLDP data of various
           types of routers is collected and LLDP data about other types of
           devices ignored (such as stations, telephones and others). If
           false, LLDP reception is disabled. Defaults to "routers-only".
           Use networkctl(1) to query the collected neighbor data. LLDP is
           only available on Ethernet links. See EmitLLDP= below for
           enabling LLDP packet emission from the local system.

       EmitLLDP=
           Controls support for Ethernet LLDP packet emission. Accepts a
           boolean parameter or the special values "nearest-bridge",
           "non-tpmr-bridge" and "customer-bridge". Defaults to false, which
           turns off LLDP packet emission. If not false, a short LLDP packet
           with information about the local system is sent out in regular
           intervals on the link. The LLDP packet will contain information
           about the local host name, the local machine ID (as stored in
           machine-id(5)) and the local interface name, as well as the
           pretty hostname of the system (as set in machine-info(5)). LLDP
           emission is only available on Ethernet links. Note that this
           setting passes data suitable for identification of host to the
           network and should thus not be enabled on untrusted networks,
           where such identification data should not be made available. Use
           this option to permit other systems to identify on which
           interfaces they are connected to this system. The three special
           values control propagation of the LLDP packets. The
           "nearest-bridge" setting permits propagation only to the nearest
           connected bridge, "non-tpmr-bridge" permits propagation across
           Two-Port MAC Relays, but not any other bridges, and
           "customer-bridge" permits propagation until a customer bridge is
           reached. For details about these concepts, see IEEE
           802.1AB-2009[4]. Note that configuring this setting to true is
           equivalent to "nearest-bridge", the recommended and most
           restricted level of propagation. See LLDP= above for an option to
           enable LLDP reception.

       BindCarrier=
           A link name or a list of link names. When set, controls the
           behavior of the current link. When all links in the list are in
           an operational down state, the current link is brought down. When
           at least one link has carrier, the current interface is brought
           up.

       Address=
           A static IPv4 or IPv6 address and its prefix length, separated by
           a "/" character. Specify this key more than once to configure
           several addresses. The format of the address must be as described
           in inet_pton(3). This is a short-hand for an [Address] section
           only containing an Address key (see below). This option may be
           specified more than once.

           If the specified address is 0.0.0.0 (for IPv4) or [::] (for
           IPv6), a new address range of the requested size is automatically
           allocated from a system-wide pool of unused ranges. The allocated
           range is checked against all current network interfaces and all
           known network configuration files to avoid address range
           conflicts. The default system-wide pool consists of
           192.168.0.0/16, 172.16.0.0/12 and 10.0.0.0/8 for IPv4, and
           fc00::/7 for IPv6. This functionality is useful to manage a large
           number of dynamically created network interfaces with the same
           network configuration and automatic address range assignment.

       Gateway=
           The gateway address, which must be in the format described in
           inet_pton(3). This is a short-hand for a [Route] section only
           containing a Gateway key. This option may be specified more than
           once.

       DNS=
           A DNS server address, which must be in the format described in
           inet_pton(3). This option may be specified more than once. This
           setting is read by systemd-resolved.service(8).

       Domains=
           The domains used for DNS host name resolution on this link. Takes
           a list of DNS domain names which are used as search suffixes for
           extending single-label host names (host names containing no dots)
           to become fully qualified domain names (FQDNs). If a single-label
           host name is resolved on this interface, each of the specified
           search domains are appended to it in turn, converting it into a
           fully qualified domain name, until one of them may be
           successfully resolved.

           The specified domains are also used for routing of DNS queries:
           look-ups for host names ending in the domains specified here are
           preferably routed to the DNS servers configured for this
           interface. If a domain name is prefixed with "~", the domain name
           becomes a pure "routing" domain, the DNS server is used for the
           given domain names only and is not used in the described domain
           search logic. By specifying a routing domain of "~."  (the tilde
           indicating definition of a routing domain, the dot referring to
           the DNS root domain which is the implied suffix of all valid DNS
           names) it is possible to route all DNS traffic preferably to the
           DNS server specified for this interface. The route domain logic
           is particularly useful on multi-homed hosts with DNS servers
           serving particular private DNS zones on each interface.

           This setting is read by systemd-resolved.service(8).

       NTP=
           An NTP server address. This option may be specified more than
           once. This setting is read by systemd-timesyncd.service(8).

       IPForward=
           Configures IP packet forwarding for the system. If enabled,
           incoming packets on any network interface will be forwarded to
           any other interfaces according to the routing table. Takes either
           a boolean argument, or the values "ipv4" or "ipv6", which only
           enable IP packet forwarding for the specified address family.
           This controls the net.ipv4.ip_forward and
           net.ipv6.conf.all.forwarding sysctl options of the network
           interface (see ip-sysctl.txt[5] for details about sysctl
           options). Defaults to "no".

           Note: this setting controls a global kernel option, and does so
           one way only: if a network that has this setting enabled is set
           up the global setting is turned on. However, it is never turned
           off again, even after all networks with this setting enabled are
           shut down again.

           To allow IP packet forwarding only between specific network
           interfaces use a firewall.

       IPMasquerade=
           Configures IP masquerading for the network interface. If enabled,
           packets forwarded from the network interface will be appear as
           coming from the local host. Takes a boolean argument. Implies
           IPForward=ipv4. Defaults to "no".

       IPv6PrivacyExtensions=
           Configures use of stateless temporary addresses that change over
           time (see RFC 4941[6], Privacy Extensions for Stateless Address
           Autoconfiguration in IPv6). Takes a boolean or the special values
           "prefer-public" and "kernel". When true, enables the privacy
           extensions and prefers temporary addresses over public addresses.
           When "prefer-public", enables the privacy extensions, but prefers
           public addresses over temporary addresses. When false, the
           privacy extensions remain disabled. When "kernel", the kernel's
           default setting will be left in place. Defaults to "no".

       IPv6AcceptRA=
           Enable or disable IPv6 Router Advertisement (RA) reception
           support for the interface. Takes a boolean parameter. If true,
           RAs are accepted; if false, RAs are ignored, independently of the
           local forwarding state. When not set, the kernel default is used,
           and RAs are accepted only when local forwarding is disabled for
           that interface. When RAs are accepted, they may trigger the start
           of the DHCPv6 client if the relevant flags are set in the RA
           data, or if no routers are found on the link.

           Further settings for the IPv6 RA support may be configured in the
           "[IPv6AcceptRA]" section, see below.

           Also see ip-sysctl.txt[5] in the kernel documentation regarding
           "accept_ra", but note that systemd's setting of 1 (i.e. true)
           corresponds to kernel's setting of 2.

       IPv6DuplicateAddressDetection=
           Configures the amount of IPv6 Duplicate Address Detection (DAD)
           probes to send. Defaults to unset.

       IPv6HopLimit=
           Configures IPv6 Hop Limit. For each router that forwards the
           packet, the hop limit is decremented by 1. When the hop limit
           field reaches zero, the packet is discarded. Defaults to unset.

       ProxyARP=
           A boolean. Configures proxy ARP. Proxy ARP is the technique in
           which one host, usually a router, answers ARP requests intended
           for another machine. By "faking" its identity, the router accepts
           responsibility for routing packets to the "real" destination.
           (see RFC 1027[7]. Defaults to unset.

       Bridge=
           The name of the bridge to add the link to.

       Bond=
           The name of the bond to add the link to.

       VRF=
           The name of the VRF to add the link to.

       VLAN=
           The name of a VLAN to create on the link. This option may be
           specified more than once.

       MACVLAN=
           The name of a MACVLAN to create on the link. This option may be
           specified more than once.

       VXLAN=
           The name of a VXLAN to create on the link. This option may be
           specified more than once.

       Tunnel=
           The name of a Tunnel to create on the link. This option may be
           specified more than once.

[ADDRESS] SECTION OPTIONS         top

       An "[Address]" section accepts the following keys. Specify several
       "[Address]" sections to configure several addresses.

       Address=
           As in the "[Network]" section. This key is mandatory.

       Peer=
           The peer address in a point-to-point connection. Accepts the same
           format as the "Address" key.

       Broadcast=
           The broadcast address, which must be in the format described in
           inet_pton(3). This key only applies to IPv4 addresses. If it is
           not given, it is derived from the "Address" key.

       Label=
           An address label.

       PreferredLifetime=
           Allows the default "preferred lifetime" of the address to be
           overridden. Only three settings are accepted: "forever" or
           "infinity" which is the default and means that the address never
           expires, and "0" which means that the address is considered
           immediately "expired" and will not be used, unless explicitly
           requested. A setting of PreferredLifetime=0 is useful for
           addresses which are added to be used only by a specific
           application, which is then configured to use them explicitly.

[ROUTE] SECTION OPTIONS         top

       The "[Route]" section accepts the following keys. Specify several
       "[Route]" sections to configure several routes.

       Gateway=
           As in the "[Network]" section.

       Destination=
           The destination prefix of the route. Possibly followed by a slash
           and the prefix length. If omitted, a full-length host route is
           assumed.

       Source=
           The source prefix of the route. Possibly followed by a slash and
           the prefix length. If omitted, a full-length host route is
           assumed.

       Metric=
           The metric of the route (an unsigned integer).

       Scope=
           The scope of the route, which can be "global", "link" or "host".
           Defaults to "global".

       PreferredSource=
           The preferred source address of the route. The address must be in
           the format described in inet_pton(3).

       Table=num
           The table identifier for the route (a number between 1 and
           4294967295, or 0 to unset). The table can be retrieved using ip
           route show table num.

[DHCP] SECTION OPTIONS         top

       The "[DHCP]" section configures the DHCPv4 and DHCP6 client, if it is
       enabled with the DHCP= setting described above:

       UseDNS=
           When true (the default), the DNS servers received from the DHCP
           server will be used and take precedence over any statically
           configured ones.

           This corresponds to the nameserver option in resolv.conf(5).

       UseNTP=
           When true (the default), the NTP servers received from the DHCP
           server will be used by systemd-timesyncd and take precedence over
           any statically configured ones.

       UseMTU=
           When true, the interface maximum transmission unit from the DHCP
           server will be used on the current link. Defaults to false.

       SendHostname=
           When true (the default), the machine's hostname will be sent to
           the DHCP server.

       UseHostname=
           When true (the default), the hostname received from the DHCP
           server will be set as the transient hostname of the system

       Hostname=
           Use this value for the hostname which is sent to the DHCP server,
           instead of machine's hostname.

       UseDomains=
           Takes a boolean argument, or the special value "route". When
           true, the domain name received from the DHCP server will be used
           as DNS search domain over this link, similar to the effect of the
           Domains= setting. If set to "route", the domain name received
           from the DHCP server will be used for routing DNS queries only,
           but not for searching, similar to the effect of the Domains=
           setting when the argument is prefixed with "~". Defaults to
           false.

           It is recommended to enable this option only on trusted networks,
           as setting this affects resolution of all host names, in
           particular of single-label names. It is generally safer to use
           the supplied domain only as routing domain, rather than as search
           domain, in order to not have it affect local resolution of
           single-label names.

           When set to true, this setting corresponds to the domain option
           in resolv.conf(5).

       UseRoutes=
           When true (the default), the static routes will be requested from
           the DHCP server and added to the routing table with a metric of
           1024.

       UseTimezone=
           When true, the timezone received from the DHCP server will be set
           as timezone of the local system. Defaults to "no".

       CriticalConnection=
           When true, the connection will never be torn down even if the
           DHCP lease expires. This is contrary to the DHCP specification,
           but may be the best choice if, say, the root filesystem relies on
           this connection. Defaults to false.

       ClientIdentifier=
           The DHCPv4 client identifier to use. Either "mac" to use the MAC
           address of the link or "duid" (the default, see below) to use an
           RFC4361-compliant Client ID.

       VendorClassIdentifier=
           The vendor class identifier used to identify vendor type and
           configuration.

       DUIDType=
           Override the global DUIDType setting for this network. See
           networkd.conf(5) for a description of possible values.

       DUIDRawData=
           Override the global DUIDRawData setting for this network. See
           networkd.conf(5) for a description of possible values.

       IAID=
           The DHCP Identity Association Identifier (IAID) for the
           interface, a 32-bit unsigned integer.

       RequestBroadcast=
           Request the server to use broadcast messages before the IP
           address has been configured. This is necessary for devices that
           cannot receive RAW packets, or that cannot receive packets at all
           before an IP address has been configured. On the other hand, this
           must not be enabled on networks where broadcasts are filtered
           out.

       RouteMetric=
           Set the routing metric for routes specified by the DHCP server.

       RouteTable=num
           The table identifier for DHCP routes (a number between 1 and
           4294967295, or 0 to unset). The table can be retrieved using ip
           route show table num.

[IPV6ACCEPTRA] SECTION OPTIONS         top

       The "[IPv6AcceptRA]" section configures the IPv6 Router Advertisement
       (RA) client, if it is enabled with the IPv6AcceptRA= setting
       described above:

       UseDNS=
           When true (the default), the DNS servers received in the Router
           Advertisement will be used and take precedence over any
           statically configured ones.

           This corresponds to the nameserver option in resolv.conf(5).

       UseDomains=
           Takes a boolean argument, or the special value "route". When
           true, the domain name received via IPv6 Router Advertisement (RA)
           will be used as DNS search domain over this link, similar to the
           effect of the Domains= setting. If set to "route", the domain
           name received via IPv6 RA will be used for routing DNS queries
           only, but not for searching, similar to the effect of the
           Domains= setting when the argument is prefixed with "~". Defaults
           to false.

           It is recommended to enable this option only on trusted networks,
           as setting this affects resolution of all host names, in
           particular of single-label names. It is generally safer to use
           the supplied domain only as routing domain, rather than as search
           domain, in order to not have it affect local resolution of
           single-label names.

           When set to true, this setting corresponds to the domain option
           in resolv.conf(5).

       RouteTable=num
           The table identifier for the routes received in the Router
           Advertisement (a number between 1 and 4294967295, or 0 to unset).
           The table can be retrieved using ip route show table num.

[DHCPSERVER] SECTION OPTIONS         top

       The "[DHCPServer]" section contains settings for the DHCP server, if
       enabled via the DHCPServer= option described above:

       PoolOffset=, PoolSize=
           Configures the pool of addresses to hand out. The pool is a
           contiguous sequence of IP addresses in the subnet configured for
           the server address, which does not include the subnet nor the
           broadcast address.  PoolOffset= takes the offset of the pool from
           the start of subnet, or zero to use the default value.  PoolSize=
           takes the number of IP addresses in the pool or zero to use the
           default value. By default, the pool starts at the first address
           after the subnet address and takes up the rest of the subnet,
           excluding the broadcast address. If the pool includes the server
           address (the default), this is reserved and not handed out to
           clients.

       DefaultLeaseTimeSec=, MaxLeaseTimeSec=
           Control the default and maximum DHCP lease time to pass to
           clients. These settings take time values in seconds or another
           common time unit, depending on the suffix. The default lease time
           is used for clients that did not ask for a specific lease time.
           If a client asks for a lease time longer than the maximum lease
           time, it is automatically shortened to the specified time. The
           default lease time defaults to 1h, the maximum lease time to 12h.
           Shorter lease times are beneficial if the configuration data in
           DHCP leases changes frequently and clients shall learn the new
           settings with shorter latencies. Longer lease times reduce the
           generated DHCP network traffic.

       EmitDNS=, DNS=
           Configures whether the DHCP leases handed out to clients shall
           contain DNS server information. The EmitDNS= setting takes a
           boolean argument and defaults to "yes". The DNS servers to pass
           to clients may be configured with the DNS= option, which takes a
           list of IPv4 addresses. If the EmitDNS= option is enabled but no
           servers configured, the servers are automatically propagated from
           an "uplink" interface that has appropriate servers set. The
           "uplink" interface is determined by the default route of the
           system with the highest priority. Note that this information is
           acquired at the time the lease is handed out, and does not take
           uplink interfaces into account that acquire DNS or NTP server
           information at a later point. DNS server propagation does not
           take /etc/resolv.conf into account. Also, note that the leases
           are not refreshed if the uplink network configuration changes. To
           ensure clients regularly acquire the most current uplink DNS
           server information, it is thus advisable to shorten the DHCP
           lease time via MaxLeaseTimeSec= described above.

       EmitNTP=, NTP=
           Similar to the EmitDNS= and DNS= settings described above, these
           settings configure whether and what NTP server information shall
           be emitted as part of the DHCP lease. The same syntax,
           propagation semantics and defaults apply as for EmitDNS= and
           DNS=.

       EmitRouter=
           Similar to the EmitDNS= setting described above, this setting
           configures whether the DHCP lease should contain the router
           option. The same syntax, propagation semantics and defaults apply
           as for EmitDNS=.

       EmitTimezone=, Timezone=
           Configures whether the DHCP leases handed out to clients shall
           contain timezone information. The EmitTimezone= setting takes a
           boolean argument and defaults to "yes". The Timezone= setting
           takes a timezone string (such as "Europe/Berlin" or "UTC") to
           pass to clients. If no explicit timezone is set, the system
           timezone of the local host is propagated, as determined by the
           /etc/localtime symlink.

[BRIDGE] SECTION OPTIONS         top

       The "[Bridge]" section accepts the following keys.

       UnicastFlood=
           A boolean. Controls whether the bridge should flood traffic for
           which an FDB entry is missing and the destination is unknown
           through this port. Defaults to on.

       HairPin=
           A boolean. Configures whether traffic may be sent back out of the
           port on which it was received. By default, this flag is false,
           and the bridge will not forward traffic back out of the receiving
           port.

       UseBPDU=
           A boolean. Configures whether STP Bridge Protocol Data Units will
           be processed by the bridge port. Defaults to yes.

       FastLeave=
           A boolean. This flag allows the bridge to immediately stop
           multicast traffic on a port that receives an IGMP Leave message.
           It is only used with IGMP snooping if enabled on the bridge.
           Defaults to off.

       AllowPortToBeRoot=
           A boolean. Configures whether a given port is allowed to become a
           root port. Only used when STP is enabled on the bridge. Defaults
           to on.

       Cost=
           Sets the "cost" of sending packets of this interface. Each port
           in a bridge may have a different speed and the cost is used to
           decide which link to use. Faster interfaces should have lower
           costs.

[BRIDGEFDB] SECTION OPTIONS         top

       The "[BridgeFDB]" section manages the forwarding database table of a
       port and accepts the following keys. Specify several "[BridgeFDB]"
       sections to configure several static MAC table entries.

       MACAddress=
           As in the "[Network]" section. This key is mandatory.

       VLANId=
           The VLAN ID for the new static MAC table entry. If omitted, no
           VLAN ID info is appended to the new static MAC table entry.

[BRIDGEVLAN] SECTION OPTIONS         top

       The "[BridgeVLAN]" section manages the VLAN ID configuration of a
       bridge port and accepts the following keys. Specify several
       "[BridgeVLAN]" sections to configure several VLAN entries. The
       VLANFiltering= option has to be enabled, see "[Bridge]" section in
       systemd.netdev(5).

       VLAN=
           The VLAN ID allowed on the port. This can be either a single ID
           or a range M-N. VLAN IDs are valid from 1 to 4094.

       EgressUntagged=
           The VLAN ID specified here will be used to untag frames on
           egress. Configuring EgressUntagged= implicates the use of VLAN=
           above and will enable the VLAN ID for ingress as well. This can
           be either a single ID or a range M-N.

       PVID=
           The Port VLAN ID specified here is assigned to all untagged
           frames at ingress.  PVID= can be used only once. Configuring
           PVID= implicates the use of VLAN= above and will enable the VLAN
           ID for ingress as well.

EXAMPLE         top

       Example 1. /etc/systemd/network/50-static.network

           [Match]
           Name=enp2s0

           [Network]
           Address=192.168.0.15/24
           Gateway=192.168.0.1

       Example 2. /etc/systemd/network/80-dhcp.network

           [Match]
           Name=en*

           [Network]
           DHCP=yes

       Example 3. /etc/systemd/network/25-bridge-static.network

           [Match]
           Name=bridge0

           [Network]
           Address=192.168.0.15/24
           Gateway=192.168.0.1
           DNS=192.168.0.1

       Example 4. /etc/systemd/network/25-bridge-slave-interface.network

           [Match]
           Name=enp2s0

           [Network]
           Bridge=bridge0

       Example 5. /etc/systemd/network/25-bridge-slave-interface-
       vlan.network

           [Match]
           Name=enp2s0

           [Network]
           Bridge=bridge0

           [BridgeVLAN]
           VLAN=1-32
           PVID=42
           EgressUntagged=42

           [BridgeVLAN]
           VLAN=100-200

           [BridgeVLAN]
           EgressUntagged=300-400

       Example 6. /etc/systemd/network/25-ipip.network

           [Match]
           Name=em1

           [Network]
           Tunnel=ipip-tun

       Example 7. /etc/systemd/network/25-sit.network

           [Match]
           Name=em1

           [Network]
           Tunnel=sit-tun

       Example 8. /etc/systemd/network/25-gre.network

           [Match]
           Name=em1

           [Network]
           Tunnel=gre-tun

       Example 9. /etc/systemd/network/25-vti.network

           [Match]
           Name=em1

           [Network]
           Tunnel=vti-tun

       Example 10. /etc/systemd/network/25-bond.network

           [Match]
           Name=bond1

           [Network]
           DHCP=yes

       Example 11. /etc/systemd/network/25-vrf.network

       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.

           [Match]
           Name=bond1

           [Network]
           VRF=vrf-test

SEE ALSO         top

       systemd(1), systemd-networkd.service(8), systemd.link(5),
       systemd.netdev(5), systemd-resolved.service(8)

NOTES         top

        1. Link-Local Multicast Name Resolution
           https://tools.ietf.org/html/rfc4795

        2. Multicast DNS
           https://tools.ietf.org/html/rfc6762

        3. DNSSEC
           https://tools.ietf.org/html/rfc4033

        4. IEEE 802.1AB-2009
           http://standards.ieee.org/getieee802/download/802.1AB-2009.pdf

        5. ip-sysctl.txt
           https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt

        6. RFC 4941
           https://tools.ietf.org/html/rfc4941

        7. RFC 1027
           https://tools.ietf.org/html/rfc1027

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a bug
       report for this manual page, see 
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.  This
       page was obtained from the project's upstream Git repository 
       ⟨https://github.com/systemd/systemd.git⟩ on 2016-10-04.  If you dis‐
       cover any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

systemd 231                                               SYSTEMD.NETWORK(5)