stable_id

This represents the identity of the connection used for various purposes.

It allows to configure multiple profiles to share the identity. Also, the stable-id can contain placeholders that are substituted dynamically and deterministically depending on the context.

The stable-id is used for generating IPv6 stable private addresses with ipv6.addr-gen-mode=stable-privacy. It is also used to seed the generated cloned MAC address for ethernet.cloned-mac-address=stable and wifi.cloned-mac-address=stable. It is also used to derive the DHCP client identifier with ipv4.dhcp-client-id=stable, the DHCPv6 DUID with ipv6.dhcp-duid=stable-[llt,ll,uuid] and the DHCP IAID with ipv4.iaid=stable and ipv6.iaid=stable.

Note that depending on the context where it is used, other parameters are also seeded into the generation algorithm. For example, a per-host key is commonly also included, so that different systems end up generating different IDs. Or with ipv6.addr-gen-mode=stable-privacy, also the device's name is included, so that different interfaces yield different addresses. The per-host key is the identity of your machine and stored in /var/lib/NetworkManager/secret_key. See NetworkManager(8) manual about the secret-key and the host identity.

The '$' character is treated special to perform dynamic substitutions at activation time. Currently, supported are "${CONNECTION}", "${DEVICE}", "${MAC}", "${BOOT}", "${RANDOM}". These effectively create unique IDs per-connection, per-device, per-boot, or every time. The "${CONNECTION}" uses the profile's connection.uuid, the "${DEVICE}" uses the interface name of the device and "${MAC}" the permanent MAC address of the device. Any unrecognized patterns following '$' are treated verbatim, however are reserved for future use. You are thus advised to avoid '$' or escape it as "$$". For example, set it to "${CONNECTION}-${BOOT}-${DEVICE}" to create a unique id for this connection that changes with every reboot and differs depending on the interface where the profile activates.

If the value is unset, a global connection default is consulted. If the value is still unset, the default is "default${CONNECTION}" go generate an ID unique per connection profile.