Dynamic ARP Inspection on Cisco Catalyst Switches
Dynamic ARP Inspection (DAI) is a security feature that allows you to prevent ARP spoofing attacks on your network. In this blog post, we will go over the steps for configuring DAI on a Cisco switch.
Step 1: Enable DAI on the desired VLAN.
To enable DAI on a particular VLAN, enter the following command:
ip arp inspection vlan vlan_number
For example, to enable DAI on VLAN 10, you would enter the following command:
ip arp inspection vlan 10
Step 2: Specify the trusted interfaces.
You can specify the interfaces that are trusted and will not be inspected by DAI by entering the following command:
ip arp inspection trust
For example, to trust interface GigabitEthernet0/1 and GigabitEthernet0/2, you would enter the following commands:
interface GigabitEthernet0/1
ip arp inspection trust
interface GigabitEthernet0/2
ip arp inspection trust
Step 3: Configure the DAI violation action.
When a device attempts to send an ARP packet with an invalid MAC address, a DAI violation occurs. You can specify the action that should be taken when a violation occurs by entering the following command:
ip arp inspection validate {src-mac | dst-mac | ip | default}
Src-mac: Validate the source MAC address of the ARP packet. Dst-mac: Validate the destination MAC address of the ARP packet. IP: Validate both the source and destination MAC addresses of the ARP packet. Default: Use the default DAI behavior. For example, to validate both the source and destination MAC addresses of the ARP packet on VLAN 10, you would enter the following command:
ip arp inspection vlan 10 validate ip
Step 4: Save the configuration.
To save the DAI configuration, enter the following command:
write memory
And that’s it! You have successfully configured DAI on your Cisco switch. Be sure to regularly check the DAI status to ensure it is functioning properly and to update the trusted interfaces as needed.