Bogon
An IP address or prefix that should never appear on the public internet, such as unallocated, reserved, or private space.
A bogon is an IP address or route that has no business appearing on the public internet. The category includes private RFC 1918 ranges (10.0.0.0/8, 192.168.0.0/16), loopback (127.0.0.0/8), link-local, multicast, and IANA-reserved or unallocated prefixes. Seeing a bogon as a packet source usually means a spoofed source address or a misconfigured router. Network operators filter bogons at the edge to drop obviously forged traffic, and Team Cymru publishes a maintained bogon list for this purpose.