networkd.conf(5) — Linux manual page


NETWORKD.CONF(5)                networkd.conf               NETWORKD.CONF(5)

NAME         top

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

SYNOPSIS         top




DESCRIPTION         top

       These configuration files control global network parameters.
       Currently the DHCP Unique Identifier (DUID).


       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

       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.


       The following options are available in the [Network] section:

           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.

           Specifies the time interval to calculate the traffic speed of
           each interface. If SpeedMeter=no, the value is ignored. Defaults
           to 10sec.

           A boolean. When true, systemd-networkd will store any routes
           configured by other tools in its memory. When false,
           systemd-networkd will not manage the foreign routes, thus they
           are kept even if KeepConfiguration= is false. Defaults to yes.


       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

       The following options are understood:

           Specifies how the DUID should be generated. See RFC 3315[1] for a
           description of all the options.

           The following values are understood:

               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.

               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

           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.

           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 The
           configured DHCP DUID should conform to the specification in RFC
           3315[2], RFC 6355[3]. To configure IAID, see

           Example 1. A DUIDType=vendor with a custom value


           This specifies a 14 byte DUID, with the type DUID-EN ("00:02"),
           enterprise number 43793 ("00:00:ab:11"), and identifier value

SEE ALSO         top

       systemd(1),, systemd-networkd.service(8),
       machine-id(5), sd_id128_get_machine_app_specific(3)

NOTES         top

        1. RFC 3315

        2. RFC 3315

        3. RFC 6355

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug
       report for this manual page, see
       ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-11-01.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-11-01.)  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 im‐
       provements to the information in this COLOPHON (which is not part of
       the original manual page), send a mail to

systemd 247                                                 NETWORKD.CONF(5)

Pages that refer to this page: