Bogon addresses: what are invalid IP ranges?

What are bogon addresses?

Bogon addresses are IP addresses reserved for special purposes and not used for regular internet communication. The term "bogon" comes from "bogus" — these are special IP ranges set aside by internet standards for specific functions like private networks, documentation, and testing.

Why bogon addresses exist. Internet protocols reserve these special addresses for important purposes:

• Private networks — your home WiFi and office networks (like 192.168.x.x).
• System functions — computer self-communication (like 127.0.0.1 localhost).
• Documentation — examples in technical guides and tutorials.
• Future use — space reserved for new internet features.

Types of bogon addresses

RFC 1918 private addresses

• 10.0.0.0/8 — 10.0.0.0 – 10.255.255.255
• 172.16.0.0/12 — 172.16.0.0 – 172.31.255.255
• 192.168.0.0/16 — 192.168.0.0 – 192.168.255.255

Your home WiFi, office network, and router admin pages use these addresses.

Special use addresses

• 0.0.0.0/8 — current network.
• 127.0.0.0/8 — loopback addresses.
• 169.254.0.0/16 — link-local (APIPA).
• 224.0.0.0/4 — multicast addresses.

System functions like localhost, automatic IP assignment, and group communications.

Standards references

• RFC 1918: Private Internet Address Allocation.
• RFC 3927: Dynamic Configuration of IPv4 Link-Local Addresses.
• RFC 5735: Special-Use IPv4 Addresses.
• RFC 6890: Special-Purpose IP Address Registries.
• IANA Registry: Special-Purpose Address Registry.

Complete bogon address list

Here's the comprehensive list of IPv4 bogon addresses that should be filtered at internet boundaries:

How bogon addresses work in practice

Home and office networks

Private addresses (192.168.x.x, 10.x.x.x) are used because:

• Every home can use the same ranges without conflict.
• Routers automatically handle the translation to public IPs.
• It saves millions of public IP addresses.
• Most routers come pre-configured to use these ranges.

System functions

Special addresses serve important purposes:

• 127.0.0.1 — your computer talking to itself (localhost).
• 169.254.x.x — automatic IP when DHCP fails.
• 224.x.x.x — group communications (like streaming).
• 0.0.0.0 — "any address" in network configurations.

When you might encounter bogon addresses

Home network setup

When setting up home networks, you'll work with private addresses:

• Router admin page: usually 192.168.1.1 or 10.0.0.1.
• Device IPs: your laptop might be 192.168.1.100.
• Port forwarding: using private IPs for game servers.
• Network troubleshooting: checking local connectivity.

Office IT management

IT professionals work with bogon addresses for:

• Internal networks: organising departments with 10.x.x.x.
• Documentation: using example IPs in network diagrams.
• Testing: lab environments with reserved addresses.
• VPN setup: connecting remote offices securely.

Why you don't need to worry

• Router filtering — consumer and business routers automatically block bogon routing.
• ISP protection — internet service providers filter bogon traffic at network edges.
• Built-in standards — network equipment follows RFC standards by default.
• Automatic updates — modern systems update bogon lists automatically.
• Protocol design — internet protocols are designed to handle these addresses correctly.

Dynamic bogons and unallocated space

Beyond static reserved ranges, "dynamic bogons" include currently unallocated IPv4 address space that may be allocated in the future. As IPv4 addresses become increasingly scarce:

• IANA exhaustion — completed in 2011, no more /8 blocks to allocate.
• RIR exhaustion — regional registries running out of space.
• Dynamic allocation — previously bogon space being allocated.
• Filtering updates — networks must update bogon lists regularly.

Test your network for bogon exposure

Use our bogon detection tool to check any IP address against the bogon list. It provides:

• Real-time detection — instant identification of bogon addresses.
• Security warnings — alerts for potentially malicious traffic.
• RFC references — detailed explanations of why addresses are invalid.
• Network context — impact analysis for your infrastructure.

Practical examples: using bogon addresses

Example: home network setup

Situation: setting up a home office network.

Using bogon addresses:

• Router: 192.168.1.1 (admin interface).
• Work laptop: 192.168.1.10.
• Home server: 192.168.1.100.
• Smart devices: 192.168.1.20–50.

Result: everything works perfectly. Your router handles all the internet communication.

Example: testing web applications

Situation: developer testing a web application.

Using bogon addresses:

• localhost: 127.0.0.1 (testing on your own computer).
• Examples: 192.0.2.1 (in documentation).
• Lab network: 10.0.0.x (isolated test environment).
• Demo servers: 203.0.113.x (safe example IPs).

Result: safe testing without affecting real internet traffic.

Key takeaways: bogon addresses serve important purposes in internet protocols; modern equipment handles bogon filtering automatically; you use bogon addresses every day (home WiFi, localhost); internet infrastructure prevents bogon routing issues; these addresses are defined by international internet standards.

Related reading: What is an IP address? · IP addressing & subnetting · Network diagnostics