NETWORKD.CONF(5) networkd.conf NETWORKD.CONF(5)
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 DHCP Unique Identifier (DUID) value used by
DHCP protocol. DHCPv4 client protocol sends IAID and DUID to the DHCP
server when acquiring a dynamic IPv4 address if ClientIdentifier=duid.
IAID and DUID allows a DHCP server to uniquely identify the machine and
the interface requesting a DHCP IP address. To configure IAID and
ClientIdentifier, see systemd.network(5).
The following options are understood:
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, see systemd.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 DHCP Unique Identifier (DUID) value used by
DHCPv6 protocol. DHCPv6 client protocol sends the DHCP Unique Identifier
and the interface Identity Association Identifier (IAID) to a DHCPv6
server when acquiring a dynamic IPv6 address. IAID and DUID allows a
DHCPv6 server to uniquely identify the machine and the interface
requesting a DHCP IP address. To configure IAID, see 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. See for details in systemd.network(5). Defaults to "yes".
Added in version 256.
SEE ALSO
systemd(1), systemd.network(5), systemd-networkd.service(8), machine-
id(5), sd_id128_get_machine_app_specific(3)
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
systemd 257.9 NETWORKD.CONF(5)
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