Best Practices to Prevent VLAN Hopping Attacks

C.

VLAN hopping attacks are a type of network security vulnerability where an attacker gains unauthorized access to switch ports on a VLAN by sending frames with fake VLAN tags. VLAN hopping can allow an attacker to access sensitive data or launch further attacks on the network.

To protect a network from VLAN hopping attacks, there are several best practices that can be implemented. Let's discuss each of the options provided in the question:

A. Enable dynamic ARP inspection: Dynamic ARP Inspection (DAI) is a security feature that helps prevent ARP spoofing attacks. DAI works by intercepting ARP packets and verifying the source IP and MAC addresses against a trusted database. If the information does not match, the packet is dropped. While DAI does not directly protect against VLAN hopping attacks, it can help mitigate the effects of these attacks by preventing attackers from spoofing ARP packets and gaining unauthorized access to the network.

B. Configure an ACL to prevent traffic from changing VLANs: Access Control Lists (ACLs) can be used to restrict traffic between VLANs. By configuring an ACL to prevent traffic from changing VLANs, an attacker would be unable to send frames with fake VLAN tags to gain unauthorized access to a VLAN. This is a useful technique for protecting against VLAN hopping attacks, but it is important to ensure that the ACL is properly configured and maintained.

C. Change native VLAN to an unused VLAN ID: The native VLAN is the VLAN that is used for untagged traffic on a trunk port. By default, the native VLAN is VLAN 1, which is a well-known VLAN and can be easily targeted by attackers. Changing the native VLAN to an unused VLAN ID can help protect against VLAN hopping attacks by making it more difficult for an attacker to send frames with fake VLAN tags.

D. Implement port security on internet-facing VLANs: Port security can be used to restrict the number of MAC addresses that are allowed on a port. By limiting the number of MAC addresses, an attacker would be unable to connect multiple devices to a port and gain unauthorized access to a VLAN. Implementing port security on internet-facing VLANs can help protect against VLAN hopping attacks by preventing an attacker from connecting a device to a port and sending frames with fake VLAN tags.

In conclusion, all of the options provided in the question can help protect a network from VLAN hopping attacks. However, the best approach will depend on the specific needs and configuration of the network. It is recommended to implement a combination of these best practices to provide layered security and reduce the risk of a successful attack.