ni6 is a security assessment tool that exploits potential flaws in the processing of ICMPv6 Node Information messages.
You can download it from the following link: https://packetstormsecurity.com/files/download/114509/ni6-v1.0.tar.gz
Source: https://packetstormsecurity.com/files/114509/IPv6-Node-Information-Assessment-Tool-1.0.html