NETWORKD.CONF(5) networkd.conf NETWORKD.CONF(5)
NAME
networkd.conf, networkd.conf.d - Global Network configuration files
SYNOPSIS
/etc/systemd/networkd.conf
/etc/systemd/networkd.conf.d/*.conf
/lib/systemd/networkd.conf.d/*.conf
DESCRIPTION
These configuration files control global network parameters. Currently
the DHCP Unique Identifier (DUID).
CONFIGURATION DIRECTORIES AND PRECEDENCE
The default configuration is defined during compilation, so a
configuration file is only needed when it is necessary to deviate from
those defaults. By default, the configuration file in /etc/systemd/
contains commented out entries showing the defaults as a guide to the
administrator. This file can be edited to create local overrides.
When packages need to customize the configuration, they can install
configuration snippets in /usr/lib/systemd/*.conf.d/ or
/usr/local/lib/systemd/*.conf.d/. The main configuration file is read
before any of the configuration directories, and has the lowest
precedence; entries in a file in any configuration directory override
entries in the single 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 with the
lexicographically latest name takes precedence. For options which
accept a list of values, entries are collected as they occur in files
sorted lexicographically.
Files in /etc/ are reserved for the local administrator, who may use
this logic to override the configuration files installed by vendor
packages. It is recommended to prefix all filenames in those
subdirectories with a two-digit number and a dash, to simplify the
ordering of the files.
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.
SpeedMeterIntervalSec=
Specifies the time interval to calculate the traffic speed of each
interface. If SpeedMeter=no, the value is ignored. Defaults to
10sec.
[DHCP] SECTION OPTIONS
This section configures the DHCP Unique Identifier (DUID) value used by
DHCP protocol. DHCPv6 client protocol sends the DHCP Unique Identifier
and the interface Identity Association Identifier (IAID) to a DHCP
server when acquiring a dynamic IPv6 address. 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.
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[1] for a
description of all the options.
The following values are understood:
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.
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).
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".
In all cases, DUIDRawData= can be used to override the actual DUID
value that is used.
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[2], RFC 6355[3]. 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".
SEE ALSO
systemd(1), systemd.network(5), systemd-networkd.service(8), machine-
id(5), sd_id128_get_machine_app_specific(3)
NOTES
1. RFC 3315
https://tools.ietf.org/html/rfc3315#section-9
2. RFC 3315
http://tools.ietf.org/html/rfc3315#section-9
3. RFC 6355
http://tools.ietf.org/html/rfc6355
systemd 245 NETWORKD.CONF(5)