Bogon Networks:
Filter what
shouldn’t exist.
Team Cymru has maintained the bogon reference for the operators defending the internet since 2002. Continuously updated data for unrouted, reserved, and unallocated IPv4 and IPv6 prefixes, in six access formats, used in production by hundreds of network operators to filter route announcements, harden ACLs, and reduce DDoS exposure. Operated for the community, not as a product.
Six ways to query the bogon list.
Pick the format that fits your stack. Real-time BGP, scriptable HTTP, DNS lookups, RIR-formatted filter sets, and human-readable lists for direct router configuration.
Why we recommend BGP. Subscribe once and your filters updateautomatically as IANA reallocates address space and as the bogons list refreshes through the day. It is the one format that maintains itself after setup, and the one format that needs a short request to provision your peering session. Every other format below is ready to fetch or query without a form.
The Bogon Route Server Project provides bogon tracking through amultihop eBGP peering session. Subscribe once. Filters updateautomatically as IANA assigns new blocks and as the fullbogons list refreshes throughout the day. Available for traditional IPv4 bogons, IPv4 fullbogons, and IPv6 fullbogons.
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FIVE MORE FORMATS, READY NOW
No cost, no request required. Fetch or query directly. Use the arrows to see all five →
Bogon Reference HTTP
Plain-text bogon lists fetchable over HTTP. Fullbogons refresh every four hours. No registration required.
Bogon Reference DNS
Query DNS to check any IPv4 or IPv6 address against bogon zones. DNSBL-style integration.
Bogon Dotted Decimal
Dotted-decimal notation with reversed-netmask for direct Cisco ACL drop-in.
Bogon Bit Notation
CIDR notation with Juniper prefix-list format. Compatible with most modern routing platforms.
Routing Registry Bogons
Bogon filter-sets published to RADb and RIPE NCC.RPSL-formatted objects for registry-aware automation.
Why We Run This
The bogon reference exists because somebody has to keep it running.
Bogon prefixes shift constantly. Address space gets allocated, reclaimed, reassigned. Filters that worked last quarter break this one. Operators who run real networks know the cost of stale reference data: bad announcements that should have been dropped, ACLs that quietly stop matching, DDoS reflection paths that open back up.
Team Cymru has maintained this reference for the operators who can’t afford that drift. We update continuously, distribute in the formats your stack actually uses, and we’ve done it for 25 years because the internet needs someone to.
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We run the bogon reference because the operators defending the internet shouldn’t have to maintain it themselves. It’s community infrastructure. We’ll keep operating it as long as the internet needs it.
Used Worldwide
Tier-1 carriers. National CSIRTs. Cloud hosting providers. Critical infrastructurenetworks. The teams running production traffic across six continents quietly relyon the same reference data, and have for two decades.
Tier-1 ISPS
National Csirts
CLOUD PROVIDERS
Hosting Networks
CRITICAL INFRASTRUCTURE
Every format on this page exists because an operator asked for it. If your stack needs something we don’t offer yet, submit a request. The team that builds and maintains the reference reads every one.
Defense is Layered
Bogon filtering hardens the routing layer. If your operational priority is hunting threats, mitigating attacks, enriching IOCs, or coordinating with the global CSIRT community, the Operational Marketplace has the right tool for the mission.
Nimbus Threat Monitor
Continuous infrastructure telemetry and threat visibility for modern defenders. Pivot from signal to attribution.
DDoS Mitigation UTRS
Coordinated BGP blackholing for volumetric attack response. Community-driven mitigation, real-time signal sharing.
MHR API
Programmatic malware hash lookups against an indexed sample corpus. Sub-second response, built for triage workflows.
CSIRT Assistance Program
Operational support for national and sector CSIRTs worldwide. Trust-network coordination and incident response.
GLOBAL DEFENDER EXCHANGE COMMUNITY
Pick your format.
Start filtering bogons.
Operated by Team Cymru for the network operators defending the internet, since 2002. Six access formats, ready when you are. Apply for BGP peering or RIR integration, or fetch the HTTP and DNS feeds without registration. Built for operators who need to filter at the routing layer, harden ACLs, and reduce DDoS exposure.