Media Access Control (MAC) Flooding

Media Access Control (MAC) flooding is a type of network attack that targets the switching infrastructure of a local area network (LAN). This attack exploits a vulnerability in the way network switches handle MAC address tables, leading to network performance degradation or even a complete denial of service.

In a typical Ethernet network, switches use MAC address tables (also known as Content Addressable Memory or CAM tables) to maintain a mapping between MAC addresses and the corresponding switch ports. This enables the switches to forward network traffic only to the appropriate destination devices.

In a MAC flooding attack, the attacker floods the switch with a large number of fake MAC addresses, overwhelming the switch's MAC address table. As a result, the switch enters a "fail-open" mode, where it starts acting like a hub instead of a switch. In this mode, the switch broadcasts incoming network traffic to all connected ports, regardless of the destination MAC address. This flooding of unnecessary traffic consumes network resources and can lead to network congestion, performance degradation, and potential denial of service for legitimate network users.

MAC flooding attacks can be mitigated through the following preventive measures:

• Port Security: Implement port security features on network switches to limit the number of MAC addresses allowed on each port. This prevents an excessive number of MAC addresses from being learned by the switch and mitigates the impact of MAC flooding attacks.
• MAC Address Aging: Configure switches to age out MAC address entries from the MAC address table after a certain period of inactivity. By removing stale or unused MAC address entries, the switch can free up resources and mitigate the impact of MAC flooding attacks.
• Dynamic MAC Address Learning: Enable dynamic MAC address learning on switches to only allow the learning of MAC addresses associated with legitimate network traffic. This prevents the switch from learning fake MAC addresses used in MAC flooding attacks.
• Network Segmentation: Implement network segmentation using VLANs (Virtual Local Area Networks) to limit the broadcast domain and isolate different parts of the network. This prevents MAC flooding attacks from affecting the entire network and helps contain the impact within a specific VLAN.
• Switch Firmware Updates: Regularly update the firmware of network switches to ensure that known vulnerabilities related to MAC flooding are patched. Stay informed about security advisories from switch vendors and promptly apply recommended updates.