What is MAC Flood Attack?

What is MAC Flood Attack?

Have you ever experienced interference in your computer from an attacker? These attackers can capture very sensitive information from a network. This article will help you learn about MAC flood attacks and how to prevent them. So what is a MAC flood attack?

MAC flood attack, also known as CAM table flooding attack, refers to a kind of network attack where the attacker connected to a switch port goes ahead and floods the switch interface with a huge number of Ethernet frames using fake and different MAC addresses.

The MAC flooding is a common challenge that many people seek to get rid of. Nobody wants attackers to capture their sensitive data from the computer or any other source. Let us discuss the MAC flooding.

MAC Flooding

Within a very short period, the MAC of the switch gets filled with fake MAC addresses or port mappings. That particular switch’s MAC has just a limited amount of memory. Therefore, it is not capable of saving any more MAC addresses in its address table.

Anytime the MAC of the switch is full and incapable of saving any more MAC address, it will enter into fail-open mode and behave like a network hub. The frames will flood to all ports, just like the broadcast communication type.

How will the attacker benefit? The machine of the attacker is delivered with all the frames between any other appliance and the victim. The attacker is now able to access and capture sensitive information/data from the network.

In an unprecedented MAC flood attack, many Ethernet frames feed the switch. Each one of them contains specific source MAC addresses by the attacker. The purpose is to devour the circumscribed memory reserved in the switch to store the MAC address table.

The consequence of this particular attack may differ across implementations, but the demanded result by the attacker is to force authorized MAC  addresses out of the MAC address table. This causes large quantities of incoming frames to flood out on all ports. The MAC flooding derives its name from this flooding.

A spiteful user may use a packet of analyzer after launching a successful MAC flooding to get data transmitted between other computers, which would not be easily assessed if the switch were operating normally. The attacker can also investigate an address resolution protocol spoofing attack that will allow them to keep access to the confidential data after the switches recover from the previous MAC flood attack.

MAC may also be used as a fundamental virtual LAN hopping attack.

Network Switch

It is a device in computer networking that connects devices on a computer network. The switches work like the network hubs though there are several differences. Switches have computers inside them where the use of physical ports connects a network. Hence switches themselves for a network.

When incoming data arrives in a switch, it forwards that data to one or more ports where that particular data is aimed to reach. A hub is less advanced, and they always broadcast the incoming data to all the ports.

The Ethernet Frame

An Ethernet refers to a connection between LAN and any other systems. It acts to control the passing of information from LAN to all other connected systems. The Ethernet frame has a source destination and MAC address. It begins with phase one[the header], and it ends with a series of checks that the user defines.

The organization determines the control checks in the frame it is being used for. Like the MAC table, the Ethernet frame has a list based on which the checks are performed. It is one of the commonest and widely used LAN frame structures in today’s world.

MAC Address

Manufacturers provide MAC addresses to all computers. The three first fields represent the manufacturer, while the other three fields represent the host computer. You can easily find your system’s MAC address from the command prompt. 

The purpose of sending data to the destined machine is accomplished with the aid of a structured table known as the MAC table. The main purpose of the attacker is to destroy the MAC table.

 How to Prevent MAC Flood Attack?

  1. Port security

There is a  feature that the vendors call “port security.” It is often used as a counter to MAC flood attacks. Several highly developed switches may be configured to reduce the number of MAC addresses learned on ports usually connected to end stations.

Cisco switches are always packed with an in-built security system that counters MAC flood attacks. Port security in cisco switches gives significant protection against  MAC flood attacks.

Also, a smaller table of secure MAC addresses should be maintained besides the traditional MAC addresses tables.

  1. Authenticating with AAA server

Vendors allow the MAC addresses to be verified against the AAA server, and these addresses are filtered afterward.

  1. Employ security measures to prevent ARP spoofing

Security features to counter ARP spoofing or IP address spoofing in other cases can also carry out additional MAC addresses filtering on unicast packets.

  1. Implementation of IEE802.1X

Implementing IEE802.1X suites allows packet filtering rules installation explicitly by an AAA server based on dynamically learned information about clients. This includes the MAC address.

The above methods are efficient in preventing the MAC flood attack.

What Is ARP Spoofing?

ARP spoofing is a type of attack whereby the attackers send falsified address resolution protocol messages so that the attacker’s MAC  address is linked with the IP address of an authenticated user in the network.

The ARP is a kind of protocol that the internet uses mostly by the IPv4 for mapping the IP address of a machine to a physical address such as MAC address, also referred to as Ethernet address.


MAC flood overwhelms the network switch with data packets which interrupt the sender to recipient flow of data that is usual with MAC addresses. The data is then blasted out across all networks. I hope this article has been enjoyable to read.

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