arp validate
Function
The arp validate command enables MAC address consistency check in an ARP packet. This function compares the source and destination MAC addresses in ARP packets with those in the Ethernet frame header.
The undo arp validate command disables MAC address consistency check in an ARP packet.
By default, MAC address consistency check in an ARP packet is disabled.
Format
arp validate { source-mac | destination-mac } *
undo arp validate { source-mac | destination-mac } *
Parameters
| Parameter | Description | Value |
|---|---|---|
| source-mac | Indicates that the device compares the source MAC address in a received ARP packet with that in the Ethernet frame header. | - |
| destination-mac | Indicates that the device compares the destination MAC address in a received ARP packet with that in the Ethernet frame header. | - |
Usage Guidelines
Usage Scenario
This function defends against attacks from bogus ARP packets in which the source and destination MAC addresses are different from those in the Ethernet frame header.
After the arp validate command is run, the gateway checks the MAC address consistency in an ARP packet before ARP learning. If the source and destination MAC addresses in an ARP packet are different from those in the Ethernet frame header, the device discards the packet as an attack. If the source and destination MAC addresses in an ARP packet are the same as those in the Ethernet frame header, the device performs ARP learning.
- If source-mac is specified:
- When receiving an ARP Request packet, the device checks only the source MAC address consistency.
- When receiving an ARP Reply packet, the device checks only the source MAC address consistency.
- If destination-mac is specified:
When receiving an ARP Request packet, the device does not check the destination MAC address consistency because the ARP Request packet is broadcast.
- When receiving an ARP Reply packet, the device checks the destination MAC address consistency.
- If source-mac and destination-mac are specified:
- When receiving an ARP Request packet, the device checks only the source MAC address consistency.
- When receiving an ARP Reply packet, the device checks the source and destination MAC address consistency.
Precautions
VLANIF interfaces do not support the arp validate command. When receiving ARP packets, a VLANIF interface checks MAC address consistency based on the rule configured on the member interface.
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