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/. Files in /etc/ are reserved for the local administrator, who may use this
       logic to override the configuration files installed by vendor packages. 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 which of
       the subdirectories they reside in. 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. 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.

[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.

           link-layer-time, link-layer, uuid
               Those values are parsed and can be used to set the DUID type field, but DUID contents must be
               provided using DUIDRawData=.

           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 generates using the machine-id
           from the /etc/machine-id file. 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), machine-id(1)

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 237                                                                                     NETWORKD.CONF(5)