We are pleased to announce the release of our Full Bogons ACLs in eleven different formats. This data is updated every four hours. For our purposes we are including private networks within the Bogon ranges. The remaining Bogons are bogus IP addresses. Bogon is also an informal name for an IP packet on the public Internet that claims to be from an area of the IP address space reserved, but not yet allocated or delegated by the Internet Assigned Numbers Authority (IANA) or a delegated Regional Internet Registry (RIR). The areas of unallocated address space are called the bogon space. Source: Wikipedia