BGP & Routing

Bogon IP Checker

Check whether an IP address or CIDR prefix is a bogon — private, reserved, documentation, loopback, or multicast address that should not appear in public routing.

Check IP or Prefix

About Bogon IP Addresses

Bogon prefixes are IP address ranges that have not been allocated for public internet use. The term "bogon" comes from "bogus" and refers to address space that should never appear in public BGP routing tables or as source/destination addresses in public traffic.

Common Bogon Categories

Private ranges (RFC 1918): 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 — used in internal networks
Loopback (RFC 5735): 127.0.0.0/8 — localhost addresses, never leave the host
Link-local (RFC 3927): 169.254.0.0/16 — auto-configuration, single segment only
Documentation (RFC 5737): 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24 — for examples and documentation
Multicast (RFC 5771): 224.0.0.0/4 — group communication, not unicast routable
Reserved: 240.0.0.0/4 and other IANA-reserved ranges not yet allocated

Why Filter Bogons?

ISPs and network operators implement bogon filtering as part of BCP38 (Network Ingress Filtering, RFC 2827) to prevent IP spoofing. Traffic claiming to originate from bogon addresses is definitively spoofed since those addresses are not routable on the public internet. MANRS (Mutually Agreed Norms for Routing Security) recommends bogon filtering as a core practice.