Page "IPv6" Paragraph 37

Privacy extensions for IPv6 have been defined to address these privacy concerns.

When privacy extensions are enabled, the operating system generates ephemeral IP addresses by concatenating a randomly generated host identifier with the assigned network prefix.

These ephemeral addresses, instead of trackable static IP addresses, are used to communicate with remote hosts.

The use of ephemeral addresses makes it difficult to accurately track a user's Internet activity by scanning activity streams for a single IPv6 address.