# networkd.conf

## NAME



           networkd.conf, networkd.conf.d - Global Network configuration
           files
    


## SYNOPSIS



               /etc/systemd/networkd.conf
               /run/systemd/networkd.conf
               /usr/local/lib/systemd/networkd.conf
               /usr/lib/systemd/networkd.conf
               /etc/systemd/networkd.conf.d/*.conf
               /run/systemd/networkd.conf.d/*.conf
               /usr/local/lib/systemd/networkd.conf.d/*.conf
               /usr/lib/systemd/networkd.conf.d/*.conf
    


## DESCRIPTION



           These configuration files control global network parameters.
    


## CONFIGURATION DIRECTORIES AND PRECEDENCE



           The default configuration is set during compilation, so
           configuration is only needed when it is necessary to deviate from
           those defaults. The main configuration file is loaded from one of
           the listed directories in order of priority, only the first file
           found is used: /etc/systemd/, /run/systemd/,
           /usr/local/lib/systemd/ [1], /usr/lib/systemd/. The vendor version
           of the file contains commented out entries showing the defaults as
           a guide to the administrator. Local overrides can also be created
           by creating drop-ins, as described below. The main configuration
           file can also be edited for this purpose (or a copy in /etc/ if it
           is shipped under /usr/), however using drop-ins for local
           configuration is recommended over modifications to the main
           configuration file.
    
           In addition to the main configuration file, drop-in configuration
           snippets are read from /usr/lib/systemd/*.conf.d/,
           /usr/local/lib/systemd/*.conf.d/, and /etc/systemd/*.conf.d/.
           Those drop-ins have higher precedence and override the main
           configuration file. Files in the *.conf.d/ configuration
           subdirectories are sorted by their filename in lexicographic
           order, regardless of in which of the subdirectories they reside.
           When multiple files specify the same option, for options which
           accept just a single value, the entry in the file sorted last
           takes precedence, and for options which accept a list of values,
           entries are collected as they occur in the sorted files.
    
           When packages need to customize the configuration, they can
           install drop-ins under /usr/. Files in /etc/ are reserved for the
           local administrator, who may use this logic to override the
           configuration files installed by vendor packages. Drop-ins have to
           be used to override package drop-ins, since the main configuration
           file has lower precedence. It is recommended to prefix all
           filenames in those subdirectories with a two-digit number and a
           dash, to simplify the ordering. This also defines a concept of
           drop-in priorities to allow OS vendors to ship drop-ins within a
           specific range lower than the range used by users. This should
           lower the risk of package drop-ins overriding accidentally
           drop-ins defined by users. It is recommended to use the range
           10-40 for drop-ins in /usr/ and the range 60-90 for drop-ins in
           /etc/ and /run/, to make sure that local and transient drop-ins
           take priority over drop-ins shipped by the OS vendor.
    
           To disable a configuration file supplied by the vendor, the
           recommended way is to place a symlink to /dev/null in the
           configuration directory in /etc/, with the same filename as the
           vendor configuration file.
    


## [NETWORK] SECTION OPTIONS



           The following options are available in the [Network] section:
    
           _SpeedMeter=_
               Takes a boolean. If set to yes, then **systemd-networkd** measures
               the traffic of each interface, and **networkctl status** _INTERFACE_
               shows the measured speed. Defaults to no.
    
               Added in version 244.
    
           _SpeedMeterIntervalSec=_
               Specifies the time interval to calculate the traffic speed of
               each interface. If _SpeedMeter=no_ , the value is ignored.
               Defaults to 10sec.
    
               Added in version 244.
    
           _ManageForeignRoutingPolicyRules=_
               A boolean. When true, **systemd-networkd** will remove rules that
               are not configured in .network files (except for rules with
               protocol "kernel"). When false, it will not remove any foreign
               rules, keeping them even if they are not configured in a
               .network file. Defaults to yes.
    
               Added in version 249.
    
           _ManageForeignRoutes=_
               A boolean. When true, **systemd-networkd** will remove routes that
               are not configured in .network files (except for routes with
               protocol "kernel", "dhcp" when _KeepConfiguration=_ is true or
               "dhcp", and "static" when _KeepConfiguration=_ is true or
               "static"). When false, it will not remove any foreign routes,
               keeping them even if they are not configured in a .network
               file. Defaults to yes.
    
               Added in version 246.
    
           _ManageForeignNextHops=_
               A boolean. When true, **systemd-networkd** will remove nexthops
               that are not configured in .network files (except for routes
               with protocol "kernel"). When false, it will not remove any
               foreign nexthops, keeping them even if they are not configured
               in a .network file. Defaults to yes.
    
               Added in version 256.
    
           _RouteTable=_
               Defines the route table name. Takes a whitespace-separated
               list of the pairs of route table name and number. The route
               table name and number in each pair are separated with a colon,
               i.e., "_name_ :_number_ ". The route table name must not be
               "default", "main", or "local", as these route table names are
               predefined with route table number 253, 254, and 255,
               respectively. The route table number must be an integer in the
               range 1...4294967295, except for predefined numbers 253, 254,
               and 255. This setting can be specified multiple times. If an
               empty string is specified, then the list specified earlier are
               cleared. Defaults to unset.
    
               Added in version 248.
    
           _IPv4Forwarding=_
               Configures IPv4 packet forwarding for the system. Takes a
               boolean value. This controls the
               net.ipv4.conf.default.forwarding and
               net.ipv4.conf.all.forwarding sysctl options. See **IP Sysctl******[2]
               for more details about the sysctl options. Defaults to unset
               and the sysctl options will not be changed.
    
               If an interface is configured with a .network file that
               enables _IPMasquerade=_ for IPv4 (that is, "ipv4" or "both"),
               this setting is implied unless explicitly specified. See
               _IPMasquerade=_ in systemd.network(5) for more details.
    
               Added in version 256.
    
           _IPv6Forwarding=_
               Configures IPv6 packet forwarding for the system. Takes a
               boolean value. This controls the
               net.ipv6.conf.default.forwarding and
               net.ipv6.conf.all.forwarding sysctl options. See **IP Sysctl******[2]
               for more details about the sysctl options. Defaults to unset
               and the sysctl options will not be changed.
    
               If an interface is configured with a .network file that
               enables _IPMasquerade=_ for IPv6 (that is, "ipv6" or "both"),
               this setting is implied unless explicitly specified. See
               _IPMasquerade=_ in systemd.network(5) for more details.
    
               Added in version 256.
    
           _IPv6PrivacyExtensions=_
               Specifies the default value for per-network
               _IPv6PrivacyExtensions=_. Takes a boolean or the special values
               "prefer-public" and "kernel". See for details in
               systemd.network(5). Defaults to "no".
    
               Added in version 254.
    
           _UseDomains=_
               Specifies the network- and protocol-independent default value
               for the same settings in [IPv6AcceptRA], [DHCPv4], and
               [DHCPv6] sections below. Takes a boolean, or the special value
               **route**. See the same setting in systemd.network(5). Defaults to
               "no".
    
               Added in version 256.
    


## [IPV6ACCEPTRA] SECTION OPTIONS



           This section configures the default setting of the Neighbor
           Discovery. The following options are available in the
           [IPv6AcceptRA] section:
    
           _UseDomains=_
               Specifies the network-independent default value for the same
               setting in the [IPv6AcceptRA] section in systemd.network(5).
               Takes a boolean, or the special value **route**. When unspecified,
               the value specified in the [Network] section in
               networkd.conf(5), which defaults to "no", will be used.
    
               Added in version 256.
    


## [IPV6ADDRESSLABEL] SECTION OPTIONS



           An [IPv6AddressLabel] section accepts the following keys. Specify
           multiple [IPv6AddressLabel] sections to configure multiple address
           labels. IPv6 address labels are used for address selection. See
           **RFC 3484******[3]. Precedence is managed by userspace, and only the
           label itself is stored in the kernel._Label=_
               The label for the prefix, an unsigned integer in the range
               0...4294967294. 0xffffffff is reserved. This setting is
               mandatory.
    
               Added in version 257.
    
           _Prefix=_
               IPv6 prefix is an address with a prefix length, separated by a
               slash "/" character. This setting is mandatory.
    
               Added in version 257.
    


## [DHCPV4] SECTION OPTIONS



           This section configures the default configurations of DHCPv4
           client. If the DHCPv4 client is enabled on an interface, then the
           configurations below will be used by default unless explicitly
           specified in the corresponding .network file. See also
           systemd.network(5).
    
           The following options are understood:
    
           _ClientIdentifier=_
               Specifies the default DHCPv4 client identifier to be used.
               Takes one of **mac** or **duid**. If set to **mac** , the MAC address of
               each link will be used. If set to **duid** , an RFC4361-compliant
               Client ID, which is the combination of IAID and DUID, is used.
               IAID can be configured by _IAID=_ in each matching .network
               file. DUID can be configured by _DUIDType=_ and _DUIDRawData=_.
               Defaults to **duid**.
    
               Added in version 258.
    
           _DUIDType=_
               Specifies how the DUID should be generated. See **RFC 3315******[4]
               for a description of all the options.
    
               This takes an integer in the range 0...65535, or one of the
               following string values:**vendor**
                   If "DUIDType=vendor", then the DUID value will be
                   generated using "43793" as the vendor identifier (systemd)
                   and hashed contents of machine-id(5). This is the default
                   if _DUIDType=_ is not specified.
    
                   Added in version 230.
    
               **uuid**
                   If "DUIDType=uuid", and _DUIDRawData=_ is not set, then the
                   product UUID is used as a DUID value. If a system does not
                   have valid product UUID, then an application-specific
                   machine-id(5) is used as a DUID value. About the
                   application-specific machine ID, see
                   sd_id128_get_machine_app_specific(3).
    
                   Added in version 230.
    
               **link-layer-time[:**_TIME_**]** , **link-layer**
                   If "link-layer-time" or "link-layer" is specified, then
                   the MAC address of the interface is used as a DUID value.
                   The value "link-layer-time" can take additional time value
                   after a colon, e.g.  "link-layer-time:2018-01-23 12:34:56
                   UTC". The default time value is "2000-01-01 00:00:00 UTC".
    
                   Added in version 240.
    
               In all cases, _DUIDRawData=_ can be used to override the actual
               DUID value that is used.
    
               Added in version 230.
    
           _DUIDRawData=_
               Specifies the DHCP DUID value as a single newline-terminated,
               hexadecimal string, with each byte separated by ":". The DUID
               that is sent is composed of the DUID type specified by
               _DUIDType=_ and the value configured here.
    
               The DUID value specified here overrides the DUID that
               systemd-networkd.service(8) generates from the machine ID. To
               configure DUID per-network, see systemd.network(5). The
               configured DHCP DUID should conform to the specification in
               **RFC 3315******[5],**RFC 6355******[6]. To configure IAID, seesystemd.network(5).
    
               **Example 1. A DUIDType=vendor with a custom value**
    
                   DUIDType=vendor
                   DUIDRawData=00:00:ab:11:f9:2a:c2:77:29:f9:5c:00
    
               This specifies a 14 byte DUID, with the type DUID-EN
               ("00:02"), enterprise number 43793 ("00:00:ab:11"), and
               identifier value "f9:2a:c2:77:29:f9:5c:00".
    
               Added in version 230.
    
           _UseDomains=_
               Same as the one in the [IPv6AcceptRA] section, but applied for
               DHCPv4 protocol.
    
               Added in version 256.
    


## [DHCPV6] SECTION OPTIONS



           This section configures the default configurations of DHCPv6
           client. If the DHCPv6 client is enabled on an interface, then the
           configurations below will be used by default unless explicitly
           specified in the corresponding .network file. See also
           systemd.network(5).
    
           The following options are understood:
    
           _DUIDType=_ , _DUIDRawData=_
               As in the [DHCPv4] section.
    
               Added in version 249.
    
           _UseDomains=_
               As in the [DHCPv4] section.
    
               Added in version 256.
    


## [DHCPSERVER] SECTION OPTIONS



           This section configures the default setting of the DHCP server.
           The following options are available in the [DHCPServer] section:
    
           _PersistLeases=_
               Specifies the default value for per-network _PersistLeases=_.
               Takes a boolean or special value "runtime". See for details in
               systemd.network(5). Defaults to "yes".
    
               Added in version 256.
    


## NOTES



            1. 💣💥🧨💥💥💣 Please note that those configuration files must
               be available at all times. If /usr/local/ is a separate
               partition, it may not be available during early boot, and must
               not be used for configuration.
    
            2. IP Sysctl
               https://docs.kernel.org/networking/ip-sysctl.html
    
            3. RFC 3484
               https://tools.ietf.org/html/rfc3484
    
            4. RFC 3315
               https://tools.ietf.org/html/rfc3315#section-9
    
            5. RFC 3315
               http://tools.ietf.org/html/rfc3315#section-9
    
            6. RFC 6355
               http://tools.ietf.org/html/rfc6355
    


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