In the OSI model, the Layer 2 is Data Link Layer. All protocols of the layer describe methods for exchanging data frames between devices over a common media. “Common media” means “local”, created by all of devices operating at the Layer 2.

The Layer 2 is a weakest link to the higher OSI Layers because if Layer 2 is compromised, hackers can work their way up. It is important for the network security engineers to remember that Layer 2 attacks typically require internal access, either from an employee or visitor.

Because almost threats originate from inside an organization, so network security specialists must mitigate attacks within the Layer 2 infrastructure. These attacks include MAC address flooding, VLAN hopping, attacks between devices on a common VLAN, DHCP starvation and DHCP spoofing, Spanning-tree compromises, MAC spoofing, ARP spoofing, Switch Spoofing, IP Spoofing, CDP manipulation …

More Understanding

• Layer 2 Security
• Understanding, Preventing, and Defending Against Layer 2 Attacks

References

• Describe Layer 2 Attacks – Part 1
• Describe Layer 2 Attacks – Part 2