Understanding Bogon Networks and Bogon Filtering

4/30/20242 min read

Understanding Bogon Networks and Bogon Filtering

In the world of computer networks and internet security, the term "bogon" refers to IP addresses that are either invalid or unallocated. These addresses are not meant to be used on the internet and can cause various security risks if allowed to pass through network filters. Bogon filtering is the process of blocking or filtering out these bogon addresses to enhance network security.

What are Bogon Networks?

Bogon networks, also known as bogon prefixes, are IP address ranges that are not officially assigned or allocated by the Internet Assigned Numbers Authority (IANA) or the regional internet registries (RIRs). These addresses fall into two main categories:

  1. IPv4 Bogons: These are IP addresses that have not been allocated by IANA or RIRs and are therefore considered invalid or unallocated.
  2. IPv6 Bogons: Similar to IPv4 bogons, these are IPv6 address ranges that have not been officially assigned or allocated.

Why is Bogon Filtering Important?

Bogon filtering plays a crucial role in network security for several reasons:

  1. Preventing IP Spoofing: Bogon filtering helps prevent IP spoofing attacks, where attackers forge the source IP address of their packets to appear as if they are coming from a legitimate source. By filtering out bogon addresses, network administrators can significantly reduce the risk of such attacks.
  2. Protecting Against DoS Attacks: Denial of Service (DoS) attacks can overwhelm a network by flooding it with a high volume of traffic. Bogon filtering can help mitigate the impact of these attacks by blocking traffic from known bogon addresses.
  3. Enhancing Network Performance: By filtering out bogon addresses, network resources can be better utilized, improving overall network performance and reducing unnecessary traffic.
  4. Complying with Internet Standards: Following best practices and internet standards, such as filtering out bogon networks, helps ensure network security and maintain the integrity of the internet as a whole.

Implementing Bogon Filtering

To implement bogon filtering, network administrators can use various methods:

  1. Access Control Lists (ACLs): ACLs can be configured on routers or firewalls to block traffic from bogon addresses.
  2. Border Gateway Protocol (BGP) Filtering: BGP filters can be set up to prevent the advertisement or acceptance of routes from bogon networks.
  3. Third-Party Services: Some organizations may opt to use third-party services that provide up-to-date bogon filtering capabilities.


Bogon networks and bogon filtering are essential components of network security. By implementing bogon filtering measures, organizations can significantly reduce the risk of IP spoofing, DoS attacks, and enhance network performance. It is crucial for network administrators to stay informed about the latest bogon address ranges and regularly update their filters to maintain a secure network environment.