A string sent to the DHCP server to identify the local machine which the DHCP server may use to customize the DHCP lease and options.
When the property is a hex string ('aa:bb:cc') it is interpreted as a binary client ID, in which case the first byte is assumed to be
the 'type' field as per RFC 2132 section 9.14 and the remaining bytes may be an hardware address (e.g. '01NMSettingIP4Config:xx
NMSettingIP4Config:xx
NMSettingIP4Config:xx
NMSettingIP4Config:xx
NMSettingIP4Config:xx
NMSettingIP4Config:xx
' where 1 is the Ethernet ARP type and the rest is a MAC address). If the property is not a hex
string it is considered as a non-hardware-address client ID and the 'type' field is set to 0.
The special values "mac" and "perm-mac" are supported, which use the current or permanent MAC address of the device to generate a client identifier with type ethernet (01). Currently, these options only work for ethernet type of links.
The special value "ipv6-duid" uses the DUID from "ipv6.dhcp-duid" property as an RFC4361-compliant client identifier. As IAID it uses "ipv4.dhcp-iaid" and falls back to "ipv6.dhcp-iaid" if unset.
The special value "duid" generates a RFC4361-compliant client identifier based on "ipv4.dhcp-iaid" and uses a DUID generated by hashing /etc/machine-id.
The special value "stable" is supported to generate a type 0 client identifier based on the stable-id (see connection.stable-id) and a per-host key. If you set the stable-id, you may want to include the "${DEVICE}" or "${MAC}" specifier to get a per-device key.
If unset, a globally configured default is used. If still unset, the default depends on the DHCP plugin.