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NETWORKD.CONF(5) networkd.conf NETWORKD.CONF(5)
networkd.conf, networkd.conf.d - Global Network configuration
files
/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
These configuration files control global network parameters.
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.
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.
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.
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.
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, 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.
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.
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.
systemd(1), systemd.network(5), systemd-networkd.service(8),
machine-id(5), sd_id128_get_machine_app_specific(3)
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
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 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover 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 258~rc2 NETWORKD.CONF(5)
Pages that refer to this page: networkctl(1), networkd.conf(5), systemd.netdev(5), systemd.network(5), systemd.directives(7), systemd.index(7), systemd.system-credentials(7), systemd-network-generator.service(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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