dealt with the ND cache poisoning attack in Section 4.10.1, SO that will not be reintroduced in this section. There are a number of ingenious ways to attack hosts and routers on a multi-access link [175] if the attacker is able to gain access to the link and also spoof its NDP packet source address. Redirecting traffic to on-link or even off-link victim hosts, preventing a host from sending traffic to off-link destinations, removing legitimate default routers from end hosts' default router list, preventing hosts completing SLAAC by purposely failing DAD procedure and advertising bogus prefixes on the link are just some well-known attacks making use of NDP's vulnerabilities [176]. All these culminate in the lack of proving the ownership of the claimed source address of the NDP message. Rogue Router Advertisements can also be an annoying issue and prevent the end host reaching its desired off-link destinations [177]. In many cases rogue Router Advertise- ments seen in the wild are unintentional: the byproduct of a badly configured host or a flawed implementation in the host operating system. Secure Neighbor Discovery SEND [146] has a mechanism that is used for showing address ownership on individual nodes and is based on CGAs [147]. SEND utilizes X.509 certificates that include the extension for IPv6 addresses [178, 179, 180] to prove that, for example, the on-link router is authorized to advertize a given IPv6 prefix. The challenge of SEND is that it requires support from both sender and receiver of the SEND protected NDP message. There are also further network and device management challenges. The required certificate provisioning, and the Resource Public Key Infrastructure (RPKI) [181] for RPKI certificates [182] handling might be an even bigger issue, preventing wider adoption than the technology itself. Another approach to addressing on-link threats is using dedicated (layer-2) devices or functions incorporated into other required networking devices that do the required tracking of source addresses, NDP messag