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Configuration restrictions and guidelines
When you configure ARP scanning and fixed ARP, follow these restrictions and guidelines:
•
IP addresses in existing ARP entries are not scanned.
•
ARP scanning will take some time. To stop an ongoing scan, press
Ctrl
+
C
. Dynamic ARP
entries are created based on ARP replies received before the scan is terminated.
•
The
arp fixup
command is a one-time operation. You can use this command again to convert
the dynamic ARP entries learned later to static.
•
Due to the limit on the total number of static ARP entries, some dynamic ARP entries might fail
the conversion.
•
To delete a static ARP entry converted from a dynamic one, use the
undo arp
ip-address
[
vpn-instance-name
] command. Use the
reset arp all
command to delete all ARP entries or
the
reset arp static
command to delete all static ARP entries.
Configuration procedure
To configure ARP scanning and fixed ARP:
Step Command
1.
Enter system view.
system-view
2.
Enter Layer 3 Ethernet interface/Layer 3
Ethernet subinterface/VLAN
interface/Layer 3 aggregate
interface/Layer 3 aggregate
subinterface view.
interface
interface-type interface-number
3.
Trigger an ARP scanning.
arp scan
[
start-ip-address
to
end-ip-address
]
4.
Return to system view.
quit
5.
Enable fixed ARP.
arp fixup
Configuring ARP gateway protection
Configure this feature on interfaces not connected to a gateway to prevent gateway spoofing attacks.
When such an interface receives an ARP packet, it checks whether the sender IP address in the
packet is consistent with that of any protected gateway. If yes, it discards the packet. If not, it handles
the packet correctly.
Configuration guidelines
Follow these guidelines when you configure ARP gateway protection:
•
You can enable ARP gateway protection for a maximum of eight gateways on an interface.
•
Do not configure both the
arp filter source
and
arp filter binding
commands on an interface.
•
If ARP gateway protection works with ARP detection, MFF, ARP fast-reply, and ARP snooping,
ARP gateway protection applies first.
