IPv6 offers a much larger address space than that of its IPv4 counterpart. The standard /64 IPv6 subnets can (in theory) accommodate approximately 1.844 * 10^19 hosts, thus resulting in a much lower host density (#hosts/#addresses) than their IPv4 counterparts. As a result, it is widely assumed that it would take a tremendous effort to perform host scanning attacks against IPv6 networks, and therefore IPv6 host scanning attacks have long been considered unfeasible. This document analyzes the IPv6 address configuration policies implemented in most popular IPv6 stacks, and identifies a number of patterns in the resulting addresses lead to a tremendous reduction in the host address search space, thus dismantling the myth that IPv6 host scanning attacks are unfeasible.
You can download it from the following link: https://packetstormsecurity.com/files/download/112060/draft-gont-opsec-ipv6-host-scanning-00.txt
Source: https://packetstormsecurity.com/files/112060/Host-Scanning-In-IPv6-Networks.html