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Understanding Dynamic ARP Inspection(DAI)

Posted on Mar 21, 2024 by
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When we talk about network security, there's an often overlooked but crucial component known as the Address Resolution Protocol (ARP). ARP is what helps your computer figure out the network address of another device. But, like many things on the internet, it's not foolproof. That's where Dynamic ARP Inspection, or DAI, comes in. This post will guide you through what DAI is, why it's important, and how it works to keep our networks safe.

Enterprise Switch

What Is ARP Spoofing?

ARP spoofing, also known as ARP poisoning, is a type of cyber attack where attackers send fake ARP messages over a local area network (LAN) to associate their MAC address with the IP address of a legitimate device. This allows attackers to intercept, modify, or redirect network traffic intended for the legitimate device, enabling various malicious activities such as eavesdropping, data theft, and session hijacking.

The consequences of ARP spoofing can be significant. It can enable a variety of attacks, including:

  • Man-in-the-middle (MitM) attacks: The attacker intercepts and potentially alters communication between two parties without their knowledge.

  • Denial of service (DoS): By sending conflicting ARP responses, the attacker can cause network traffic to be dropped or sent to non-existent hosts.

  • Session hijacking: With control over the network traffic, an attacker can hijack ongoing sessions, steal session tokens, cookies, and passwords to gain unauthorized access to applications.

  • Malware dissemination: An attacker could modify the traffic to include malicious payloads, leading to malware infection on the targeted devices.

What Is Dynamic ARP Inspection (DAI)?

Dynamic ARP Inspection is like a bouncer for your network. It checks the ID of the data packets that come in through ARP messages. This is important because ARP doesn't have a way to confirm who's who on its own. DAI steps in to make sure data packets are coming from trusted devices. It does this by checking a trusted list of MAC-to-IP address bindings, known as a DHCP binding table. So, DAI keeps an eye out for any fishy business.

For added security, consider implementing DAI alongside the reliable FS S3910-24TS switch to keep an eye out for any fishy business.

Enterprise Switch

How DAI work

DAI validates packet authenticity by inspecting IP-to-MAC address bindings. Once confirmed as valid, packets are forwarded to their intended destination. However, any packets with invalid IP-to-MAC address bindings, failing the inspection process, are dropped by DAI. This ensures that only legitimate ARP requests and responses are transmitted. When enabled, DAI performs three key functions:

  • Intercepting all ARP requests and responses on untrusted ports.

  • Verifying the validity of intercepted packets' IP-to-MAC address bindings before updating the local ARP cache or forwarding them to their destination.

  • Discarding any ARP packets deemed invalid due to containing incorrect or invalid IP-to-MAC address bindings.

Conclusion

Dynamic ARP Inspection (DAI) is a vital security feature for enterprise switches, helping safeguard networks against ARP spoofing attacks. Implementing DAI alongside other security measures can significantly reduce the risk of ARP-related security incidents and protect the overall integrity of the network infrastructure.

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