Addresses for Carrier-grade NAT, Teredo, and 6to4 and documentation prefixes also fall into this category.
Many ISPs and end-user firewalls filter and block bogons, because they have no legitimate use, and usually are the result of accidental misconfiguration or malicious intent.
Bogons can be filtered by using router access-control lists (ACLs), or by BGP blackholing.
Announcements of new assignments are often published on network operators' mailing lists (such as NANOG) to ensure that bogon filtering can be removed for addresses that have become legitimate.
[7] As of November 2011[update], the Internet Engineering Task Force (IETF) recommends that, since there are no longer any unallocated IPv4 /8s, IPv4 bogon filters based on registration status should be removed.