The Atomic ARP engine is a signature engine that defines basic Layer 2 ARP signatures and provides more advanced detection of the ARP spoof tools dsniff and ettercap. ARP spoofing is an attack that involves sending spoofed ARP messages over a local area network to associate the attacker’s MAC address with the IP address of the target. The Atomic ARP engine inspects the Layer 2 ARP protocol and compares the ARP requests and replies with the MAC address table to detect any anomalies or inconsistencies. The Atomic ARP engine can also detect gratuitous ARP messages, which are unsolicited ARP replies that can be used to poison the ARP cache of other hosts. The Atomic ARP engine is different from other IPS engines because most engines are based on Layer 3 IP protocol. References :=