ARP Inspection

ARP Inspection is a security feature used in network and infrastructure security to protect local area networks (LANs) against ARP spoofing and ARP poisoning attacks. The Address Resolution Protocol (ARP) translates IP addresses into MAC addresses for communication between devices on the same network segment. Attackers exploit this process by sending forged ARP messages, associating their own MAC address with a legitimate device's IP address — such as the default gateway — enabling man-in-the-middle attacks, session hijacking, or denial-of-service scenarios.

To prevent these threats, ARP Inspection intercepts and validates all ARP packets on the network by cross-referencing the sender's IP and MAC address against a trusted database, typically built from DHCP snooping binding tables or manually configured static entries. Any ARP packet that fails validation — indicating a forged or unauthorized IP-to-MAC binding — is immediately dropped, and an alert is generated. By enforcing the integrity of ARP communications at Layer 2, ARP Inspection serves as a critical component in a defense-in-depth cybersecurity strategy, safeguarding network resources, data confidentiality, and user privacy against common layer 2 exploits.