Configuring ARP Gateway Anti-Collision

Context

If an attacker forges the gateway address to send ARP packets with the source IP address being the IP address of the gateway on the LAN, ARP entries on hosts in the LAN record the incorrect gateway address. As a result, all traffic from user hosts to the gateway is sent to the attacker and the attacker intercepts user information. Communication of users is interrupted.

To prevent bogus gateway attacks, enable ARP gateway anti-collision on the gateway. The gateway considers a gateway collision to have occurred when a received ARP packet meets either of the following conditions:

The source IP address in the ARP packet is the same as the IP address of the VLANIF interface matching the inbound interface of the packet.
The source IP address in the ARP packet is the virtual IP address of the inbound interface but the source MAC address in the ARP packet is not the virtual MAC address of the VRRP group.

The device generates an ARP anti-collision entry and discards the received packets with the same source MAC address and VLAN ID in a specified period. This function prevents ARP packets with the bogus gateway address from being broadcast in a VLAN.

Only the S5720-EI, S5720-HI, S5720I-SI, S5720S-SI, S5720-SI, S5735-L, S5735S-L, S5735S-L-M, S5735-S, S5735S-S, S5735-S-I, S5730-HI, S5730S-EI, S5730-SI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720-LI, S6720S-EI, S6720S-LI, S6720S-SI, S6720-SI, S6730-H, S6730S-H, S6730-S, and S6730S-S support this function.

Procedure

Run system-view
The system view is displayed.
Run arp anti-attack gateway-duplicate enable
ARP gateway anti-collision is enabled.

By default, ARP gateway anti-collision is disabled.