If you do not specify a value for the pps argument in the arp rate-limit command, the default rate limit value applies. Packets that exceed the rate limit are discarded.

Examples

# Enable the ARP packet rate limit feature on GigabitEthernet 1/0/1, and set the maximum ARP packet rate to 50 pps.

<Sysname> system-view

[Sysname] interface gigabitethernet 1/0/1

[Sysname-GigabitEthernet1/0/1] arp rate-limit 50

arp rate-limit log enable

Use arp rate-limit log enable to enable logging for ARP packet rate limit.

Use undo arp rate-limit log enable to disable logging for ARP packet rate limit.

Syntax

arp rate-limit log enable

undo arp rate-limit log enable

Default

Logging for ARP packet rate limit is disabled.

Views

System view

Predefined user roles

network-admin

Usage guidelines

When logging for ARP packet rate limit is enabled, the device sends the highest threshold-crossed ARP packet rate within the sending interval in a log message to the information center. You can configure the information center module to set the log output rules. For more information about information center, see System Management Configuration Guide.

Examples

# Enable logging for ARP packet rate limit.

<Sysname> system-view

[Sysname] arp rate-limit log enable

arp rate-limit log interval

Use arp rate-limit log interval to set the notification and log message sending interval for ARP packet rate limit.

Use undo arp rate-limit log interval to restore the default.

Syntax

arp rate-limit log interval interval

undo arp rate-limit log interval

Default

The device sends notifications or log messages every 60 seconds when the rate of ARP packets received on an interface exceeds the limit.

Views

System view

Predefined user roles

network-admin

Parameters

interval: Specifies an interval in the range of 1 to 86400 seconds.

Usage guidelines

To change the default interval and activate it, you must enable ARP packet rate limit and enable sending notifications or log messages for ARP packet rate limit.

Examples

# Set the device to send notifications and log messages every 120 seconds when the rate of ARP packets received on an interface exceeds the limit.

<Sysname> system-view

[Sysname] arp rate-limit log interval 120

Related commands

arp rate-limit

arp rate-limit log enable

snmp-agent trap enable arp

Use snmp-agent trap enable arp to enable SNMP notifications for ARP.

Use undo snmp-agent trap enable arp to disable SNMP notifications for ARP.

Syntax

snmp-agent trap enable arp [ rate-limit ]

undo snmp-agent trap enable arp [ rate-limit ]

Default

SNMP notifications for ARP is disabled.

Views

System view

Predefined user roles

network-admin

Parameters

rate-limit: Specifies the ARP packet rate limit feature.

Usage guidelines

After you enable SNMP notifications for ARP, the device generates a notification that includes the highest threshold-crossed ARP packet rate within the sending interval.

For ARP event notifications to be sent correctly, you must also configure SNMP on the device. For more information about SNMP configuration, see Network Management and Monitoring Configuration Guide.

Examples

# Enable SNMP notifications for ARP packet rate limit.

<Sysname> system-view

[Sysname] snmp-agent trap enable arp rate-limit

Source MAC-based ARP attack detection commands

arp source-mac

Use arp source-mac to enable the source MAC-based ARP attack detection feature and specify a handling method.

Use undo arp source-mac to disable the source MAC-based ARP attack detection feature.

Syntax

arp source-mac { filter | monitor }

undo arp source-mac [ filter | monitor ]

Default

The source MAC-based ARP attack detection feature is disabled.

Views

System view

Predefined user roles

network-admin

Parameters

filter: Specifies the filter handling method.

monitor: Specifies the monitor handling method.

Usage guidelines

Configure this feature on the gateways.

This feature checks the number of ARP packets delivered to the CPU. If the number of packets from the same MAC address within 5 seconds exceeds a threshold, the device generates an ARP attack entry for the MAC address. Before the entry ages out, the device handles the attack by using either of the following methods:

· Monitor—Only generates log messages.

· Filter—Generates log messages and filters out subsequent ARP packets from the MAC address.

Make sure you have enabled the ARP logging feature before enabling the source MAC-based ARP attack detection feature. For information about the ARP logging feature, see ARP configuration in Network Connectivity Configuration Guide.

If you do not specify any handling method in the undo arp source-mac command, the command disables this feature.

Examples

# Enable the source MAC-based ARP attack detection feature and specify the filter handling method.

<Sysname> system-view

[Sysname] arp source-mac filter

arp source-mac aging-time

Use arp source-mac aging-time to set the aging time for ARP attack entries.

Use undo arp source-mac aging-time to restore the default.

Syntax

arp source-mac aging-time time

undo arp source-mac aging-time

Default

The aging time for ARP attack entries is 300 seconds.

Views

System view

Predefined user roles

network-admin

Parameters

time: Sets the aging time for ARP attack entries, in the range of 60 to 6000 seconds.

Examples

# Set the aging time for ARP attack entries to 60 seconds.

<Sysname> system-view

[Sysname] arp source-mac aging-time 60

arp source-mac exclude-mac

Use arp source-mac exclude-mac to exclude specific MAC addresses from source MAC-based ARP attack detection.

Use undo arp source-mac exclude-mac to remove the excluded MAC addresses from source MAC-based ARP attack detection.

Syntax

arp source-mac exclude-mac mac-address&<1-n>

undo arp source-mac exclude-mac [ mac-address&<1-n> ]

Default

No MAC addresses are excluded from source MAC-based ARP attack detection.

Views

System view

Predefined user roles

network-admin

Parameters

mac-address&<1-10>: Specifies up to n excluded MAC addresses in the format of H-H-H. The value for n is 10.

Usage guidelines

If you do not specify a MAC address, the undo arp source-mac exclude-mac command removes all excluded MAC addresses.

Examples

# Exclude a MAC address from source MAC-based ARP attack detection.

<Sysname> system-view

[Sysname] arp source-mac exclude-mac 001e-1200-0213

arp source-mac threshold

Use arp source-mac threshold to set the threshold for source MAC-based ARP attack detection. If the number of ARP packets sent from a MAC address within 5 seconds exceeds this threshold, the device recognizes this as an attack.

Use undo arp source-mac threshold to restore the default.

Syntax

arp source-mac threshold threshold-value

undo arp source-mac threshold

Default

The threshold for source MAC-based ARP attack detection is 30.

Views

System view

Predefined user roles

network-admin

Parameters

threshold-value: Specifies the threshold for source MAC-based ARP attack detection. The value range is 1 to 5000.

Examples

# Set the threshold for source MAC-based ARP attack detection to 30.

<Sysname> system-view

[Sysname] arp source-mac threshold 30

display arp source-mac

Use display arp source-mac to display ARP attack entries detected by source MAC-based ARP attack detection.

Syntax

display arp source-mac [ interface interface-type interface-number ]

Views

Any view

Predefined user roles

network-admin

network-operator

Parameters

interface interface-type interface-number: Specifies an interface by its type and number.

Examples

# Display the ARP attack entries detected by source MAC-based ARP attack detection on GigabitEthernet 1/0/1.

<Sysname> display arp source-mac interface gigabitethernet 1/0/1

Source-MAC VLAN ID Interface Aging-time

23f3-1122-3344 4094 GE1/0/1 10

Table 2 Command output

Field	Description
Source-MAC	Source MAC address of the attack.
VLAN ID	ID of the VLAN in which the attack was detected.
Interface	Interface on which the attack was detected.
Aging-time	Aging time for the ARP attack entry, in minutes.

display arp source-mac statistics

Use display arp source-mac statistics to display statistics for packets dropped by source MAC-based ARP attack detection.

Syntax

display arp source-mac statistics

Views

Any view

Predefined user roles

network-admin

network-operator

Parameters

Examples

# Display statistics for packets dropped by source MAC-based ARP attack detection.

<Sysname> display arp source-mac statistics

Dropped ARP packets:23321

Table 3 Command output

Field	Description
Dropped ARP packets	Number of packets dropped by source MAC-based ARP attack detection.

‌

Related commands

arp source-mac

reset arp source-mac statistics

Use reset arp source-mac statistics to clear statistics of packets dropped by source MAC-based ARP attack detection.

Syntax

reset arp source-mac statistics

Views

User view

Predefined user roles

network-admin

Parameters

all: Clear all statistics of packets.

slot slot-number: Specifies a VM by its slot number. (vBRAS-CPs)

Usage guidelines

If you do not specify any parameter, the command clears all statistics of packets dropped by source MAC-based ARP attack detection.

Examples

# Clear all statistics of packets dropped by source MAC-based ARP attack detection.

<Sysname> reset arp source-mac statistics

Related commands

display arp source-mac statistics

ARP packet source MAC consistency check commands

arp valid-check enable

Use arp valid-check enable to enable ARP packet source MAC address consistency check.

Use undo arp valid-check enable to disable ARP packet source MAC address consistency check.

Syntax

arp valid-check enable

undo arp valid-check enable

Default

ARP packet source MAC address consistency check is disabled.

Views

System view

Predefined user roles

network-admin

Usage guidelines

Configure this feature on gateways. The gateways can filter out ARP packets whose source MAC address in the Ethernet header is different from the sender MAC address in the message body.

Examples

# Enable ARP packet source MAC address consistency check.

<Sysname> system-view

[Sysname] arp valid-check enable

display arp valid-check statistics

Use display arp valid-check statistics to display statistics for packets dropped by ARP packet source MAC address consistency check.

Syntax

display arp valid-check statistics

Views

Any view

Predefined user roles

network-admin

network-operator

Parameters

Examples

# Display statistics for packets dropped by ARP packet source MAC address consistency check.

<Sysname> display arp valid-check statistics

Dropped ARP packets: 23321

Table 4 Command output

Field	Description
Dropped ARP packets	Number of packets dropped by ARP packet source MAC address consistency check.

‌

Related commands

arp valid-check enable

reset arp valid-check statistics

Use reset arp valid-check statistics to clear statistics for packets dropped by ARP packet source MAC address consistency check.

Syntax

reset arp valid-check statistics

Views

User view

Predefined user roles

network-admin

Parameters

all: Specifies all statistics for packets dropped by ARP packet source MAC address consistency check.

Examples

# Clear statistics for packets dropped by ARP packet source MAC address consistency check.

<Sysname> reset arp valid-check statistics

Related commands

display arp valid-check statistics

ARP active acknowledgement commands

arp active-ack enable

Use arp active-ack enable to enable the ARP active acknowledgement feature.

Use undo arp active-ack enable to disable the ARP active acknowledgement feature.

Syntax

arp active-ack [ strict ] enable

undo arp active-ack [ strict ] enable

Default

The ARP active acknowledgement feature is disabled.

Views

System view

Predefined user roles

network-admin

Parameters

strict: Enables strict mode for ARP active acknowledgement.

Usage guidelines

Configure this feature on gateways to prevent user spoofing.

Examples

# Enable the ARP active acknowledgement feature.

<Sysname> system-view

[Sysname] arp active-ack enable

Authorized ARP commands

arp authorized enable

Use arp authorized enable to enable authorized ARP on an interface.

Use undo arp authorized enable to disable authorized ARP on an interface.

Syntax

arp authorized enable

undo arp authorized enable

Default

Authorized ARP is disabled on the interface.

Views

Layer 3 Ethernet interface view

Layer 3 Ethernet subinterface view

VLAN interface view

Predefined user roles

network-admin

Examples

# Enable authorized ARP on VLAN-interface 200.

<Sysname> system-view

[Sysname] interface vlan-interface 200

[Sysname-Vlan-interface200] arp authorized enable

ARP attack detection commands

arp detection enable

Use arp detection enable to enable ARP attack detection.

Use undo arp detection enable to disable ARP attack detection.

Syntax

arp detection enable

undo arp detection enable

Default

ARP attack detection is disabled.

Views

VLAN view

Predefined user roles

network-admin

Usage guidelines

A Layer 2 Ethernet interface is enabled with ARP attack detection after you enable ARP attack detection on the interface or in the VLAN to which the interface belongs.

A Layer 2 Ethernet interface is disabled with ARP attack detection only after you disable ARP attack detection both on the interface and in the VLAN to which the interface belongs.

If a Layer 2 Ethernet interface is both enabled with ARP attack detection and configured as an ARP trusted port, the system does not perform ARP attack detection on packets received on the interface.

Examples

# Enable ARP attack detection for VLAN 2.

<Sysname> system-view

[Sysname] vlan 2

[Sysname-vlan2] arp detection enable

Related commands

arp detection rule

display arp detection

arp detection log enable

Use arp detection log enable to enable ARP attack detection logging.

Use undo arp detection log enable to disable ARP attack detection logging.

Syntax

arp detection log enable [ interval interval | number number | threshold threshold-value ] *

undo arp detection log enable

Default

ARP attack detection logging is disabled.

Views

System view

Predefined user roles

network-admin

Parameters

interval interval: Specifies the interval for sending ARP attack detection logs to the information center, in seconds. The value for the interval argument can be 0 or a value in the range of 10 to 3600. The default value is 60. If you set the interval to 0 seconds, the device sends ARP attack detection logs to the information center immediately.

number number: Specifies the maximum number of ARP attack detection logs for each log output. The value range for the number argument is 1 to 128, and the default value is 128.

threshold threshold-value: Specifies the per-destination address threshold for ARP attack detection logging. The value range for the threshold-value argument is 1 to 128, and the default is 1.

Usage guidelines

This feature enables the device to generate ARP detection logs and send them to the information center. For information about the log destination and output rule configuration in the information center, see System Management Configuration Guide.

As a best practice, disable this feature if the log generation affects the device performance.

Excessive number of logs not only affects the device performance, but also makes it difficult for you to locate logs for specific events. To resolve the issue, you can adjust the maximum number of ARP attack detection logs for each log output. The logs that exceed the number limit will not be output and displayed. In addition, you can also adjust the per-destination address threshold for logging. The device generates a log only when the number of packets destined for a destination address reaches or exceeds the threshold.

A card, member device, or device can send a maximum of 128 ARP detection logs each time.

Examples

# Enable ARP attack detection logging.

<Sysname> system-view

[Sysname] arp detection log enable

arp detection port-match-ignore

Use arp detection port-match-ignore to ignore ingress ports of ARP packets during user validity check.

Use undo arp detection port-match-ignore to remove the configuration.

Syntax

arp detection port-match-ignore

undo arp detection port-match-ignore

Default

Ingress ports of ARP packets are checked for user invalidity.

Views

System view

Predefined user roles

network-admin

Usage guidelines

This command configures ARP attack detection to ignore the ingress port information of ARP packets when the packets are compared with the entries used for user validity check.

Examples

# Ignore ingress ports of ARP packets during user validity check.

<Sysname> system-view

[Sysname] arp detection port-match-ignore

Related commands

arp detection enable

arp detection rule

Use arp detection rule to configure a user validity check rule.

Use undo arp detection rule to delete a user validity check rule.

Syntax

arp detection rule rule-id { deny | permit } ip { ip-address [ mask ] | any } mac { mac-address [ mask ] | any } [ vlan vlan-id ]

undo arp detection rule [ rule-id ]

Default

No user validity check rule is configured.

Views

System view

Predefined user roles

network-admin

Parameters

rule-id: Assigns an ID to the user validity check rule. The ID value range is 0 to 511. A smaller value represents a higher priority.

deny: Denies matching ARP packets.

permit: Permits matching ARP packets.

ip { ip-address [ mask ] | any }: Specifies the sender IP address as the match criterion.

· ip-address: Specifies an IP address in dotted decimal notation.

· mask: Specifies the address mask in dotted decimal notation. If you do not specify the mask, the ip-address argument specifies a host IP address.

· any: Matches any IP address.

mac { mac-address [ mask ] | any }: Specifies the sender MAC address as the match criterion.

· mac-address: Specifies a MAC address in the H-H-H format.

· mask: Specifies the MAC address mask in the H-H-H format. If you do not specify the mask, the argument specifies the host MAC address.

· any: Matches any MAC address.

vlan vlan-id: Specifies the ID of a VLAN in the specified rule. The value range for the vlan-id argument is 1 to 4094. If you do not specify a VLAN, the packets' VLAN information is not checked.

Usage guidelines

A user validity check rule takes effect only when ARP attack detection is enabled.

If you do not specify a rule ID, the undo arp detection rule command deletes all user validity check rules.

Examples

# Configure a user validity check rule and enable ARP detection for VLAN 2.

<Sysname> system-view

[Sysname] arp detection rule 0 permit ip 10.1.1.1 255.255.0.0 mac 0001-0203-0405 ffff-ffff-0000

[Sysname] vlan 2

[Sysname-vlan2] arp detection enable

Related commands

arp detection enable

arp detection trust

Use arp detection trust to configure an interface as an ARP trusted interface or configure an AC as an ARP trusted AC.

Use undo arp detection trust to restore the default.

Syntax

arp detection trust

undo arp detection trust

Default

An interface is an ARP untrusted interface. An AC is an ARP untrusted AC.

Views

Layer 2 Ethernet interface view

Layer 2 aggregate interface view

Predefined user roles

network-admin

Examples

# Configure GigabitEthernet 1/0/1 as an ARP trusted interface.

<Sysname> system-view

[Sysname] interface gigabitethernet 1/0/1

[Sysname-GigabitEthernet1/0/1] arp detection trust

arp detection validate

Use arp detection validate to enable ARP packet validity check.

Use undo arp detection validate to disable ARP packet validity check.

Syntax

arp detection validate { dst-mac | ip | src-mac } *

undo arp detection validate [ dst-mac | ip | src-mac ] *

Default

ARP packet validity check is disabled.

Views

System view

Predefined user roles

network-admin

Parameters

dst-mac: Checks the target MAC address of ARP responses. If the target MAC address is all-zero, all-one, or inconsistent with the destination MAC address in the Ethernet header, the packet is considered invalid and discarded.

ip: Checks the sender and target IP addresses of ARP replies, and the sender IP address of ARP requests. All-one or multicast IP addresses are considered invalid and the corresponding packets are discarded.

src-mac: Checks whether the sender MAC address in the message body is identical to the source MAC address in the Ethernet header. If they are identical, the packet is forwarded. Otherwise, the packet is discarded.

Usage guidelines

You can specify more than one object to be checked in one command line.

If no keyword is specified, the undo arp detection validate command disables ARP packet validity check for all objects.

Examples

# Enable ARP packet validity check by checking the MAC addresses and IP addresses of ARP packets.

<Sysname> system-view

[Sysname] arp detection validate dst-mac ip src-mac

arp restricted-forwarding enable

Use arp restricted-forwarding enable to enable ARP restricted forwarding.

Use undo arp restricted-forwarding enable to disable ARP restricted forwarding.

Syntax

arp restricted-forwarding enable

undo arp restricted-forwarding enable

Default

ARP restricted forwarding is disabled.

Views

VLAN view

Predefined user roles

network-admin

Examples

# Enable ARP restricted forwarding in VLAN 2.

<Sysname> system-view

[Sysname] vlan 2

[Sysname-vlan2] arp restricted-forwarding enable

display arp detection

Use display arp detection to display the VLANs that are enabled with ARP attack detection.

Syntax

display arp detection

Views

Any view

Predefined user roles

network-admin

network-operator

Examples

# Display the VLANs that are enabled with ARP attack detection.

<Sysname> display arp detection

ARP detection is enabled in the following VLANs:

1-2, 4-5

Related commands

arp detection enable

display arp detection statistics attack-source

Use display arp detection statistics attack-source to display statistics for ARP attack sources.

Syntax

display arp detection statistics attack-source

Views

Any view

Predefined user roles

network-admin

network-operator

Usage guidelines

This command displays a maximum of 1023 statistic entries for ARP attack sources and 1 identification entry.

When the maximum number is reached for the first time, the device overwrites the oldest statistics entry with the newest statistic entry and generates an identification entry. The parameters in the identification entry are as follows:

· The Interface, VLAN, MAC address, and IP address fields are empty.

· The Number field displays the value of the Number filed in the old entry that has been overwritten.

· The Time field displays the time when the identification entry was generated.

Subsequently, each time a new statistic entry is generated, the device updates the identification entry as follows:

· Adds the Number field value of the new entry to the current value of the Number field.

· Replaces the Time field value with the time when this identification entry was updated.

Examples

# Display statistics for ARP attack sources on slot 1.

<Sysname> display arp detection statistics attack-source slot 1

Interface VLAN MAC address IP address Number Time

GE1/0/1 1 0005-0001-0001 10.1.1.14 24 17:09:56

03-27-2017

Table 5 Command output

Field	Description
Interface	Receiving interface of ARP attack packets.
VLAN	VLAN to which ARP attack packets belong.
MAC address	Sender MAC address in ARP attack packets.
IP address	Sender IP address in ARP attack packets.
Number	Number of ARP attack packets dropped by ARP attack detection.
Time	The most recent time when ARP attack detection dropped an ARP attack packet.

Related commands

arp detection enable

display arp detection statistics packet-drop

Use display arp detection statistics packet-drop to display statistics for packets dropped by ARP attack detection.

Syntax

display arp detection statistics packet-drop [ interface interface-type interface-number ]

Views

Any view

Predefined user roles

network-admin

network-operator

Parameters

interface interface-type interface-number: Specifies an interface by its type and number. If you do not specify an interface, this command displays dropped packet statistics for all interfaces.

Usage guidelines

This command displays numbers of packets discarded by user validity check and ARP packet validity check on interfaces.

Examples

# Display statistics for packets dropped by ARP attack detection.

<Sysname> display arp detection statistics packet-drop

State: U-Untrusted T-Trusted

ARP packets dropped by ARP inspect checking:

Interface(State) IP Src-MAC Dst-MAC Inspect

GE1/0/1(U) 40 0 0 78

GE1/0/2(U) 0 0 0 0

GE1/0/3(T) 0 0 0 0

GE1/0/4(U) 0 0 30 0

Table 6 Command output

Field	Description
State	State of an interface: · U—ARP untrusted interface. · T—ARP trusted interface.
Interface(State)	Inbound interface of ARP packets. State specifies the port state, trusted or untrusted.
IP	Number of ARP packets discarded due to invalid sender and target IP addresses.
Src-MAC	Number of ARP packets discarded due to invalid source MAC address.
Dst-MAC	Number of ARP packets discarded due to invalid destination MAC address.
Inspect	Number of ARP packets that failed to pass user validity check.

Related commands

reset arp detection statistics packet-drop

reset arp detection statistics attack-source

Use reset arp detection statistics attack-source to clear statistics for ARP attack sources.

Syntax

reset arp detection statistics attack-source

Views

User view

Predefined user roles

network-admin

Examples

# Clear statistics for ARP attack sources.

<Sysname> reset arp detection statistics attack-source

Related commands

arp detection enable

display arp detection statistics attack-source

reset arp detection statistics packet-drop

Use reset arp detection statistics packet-drop to clear statistics for packets dropped by ARP attack detection.

Syntax

reset arp detection statistics packet-drop [ interface interface-type interface-number ]

Views

User view

Predefined user roles

network-admin

Parameters

interface interface-type interface-number: Specifies an interface by its type and number. If you do not specify an interface, this command clears dropped packet statistics for all interfaces.

Examples

# Clear statistics for packets dropped by ARP attack detection.

<Sysname> reset arp detection statistics packet-drop

Related commands

display arp detection statistics packet-drop

ARP scanning and fixed ARP commands

arp fixup

Use arp fixup to convert existing dynamic ARP entries to static ARP entries.

Use undo arp fixup to convert valid static ARP entries to dynamic ARP entries and delete invalid static ARP entries.

Syntax

arp fixup

undo arp fixup

Views

System view

Predefined user roles

network-admin

Usage guidelines

The ARP conversion is a one-time operation. You can use this command again to convert the dynamic ARP entries learned later to static.

The static ARP entries converted from dynamic ARP entries have the same attributes as the manually configured static ARP entries. Due to the device's limit on the total number of static ARP entries, some dynamic ARP entries might fail the conversion.

The static ARP entries after conversion can include the following entries:

· Existing dynamic and static ARP entries before conversion.

· New dynamic ARP entries learned during the conversion.

Dynamic ARP entries that are aged out during the conversion are not converted to static ARP entries.

To delete a static ARP entry changed from a dynamic one, use the undo arp ip-address command. To delete all such static ARP entries, use the reset arp all or reset arp static command.

Examples

# Convert existing dynamic ARP entries to static ARP entries.

<Sysname> system-view

[Sysname] arp fixup

arp scan

Use arp scan to trigger an ARP scanning in an address range.

Syntax

arp scan [ start-ip-address to end-ip-address ]

Views

Layer 3 Ethernet interface view

Layer 3 Ethernet subinterface view

VLAN interface view

Predefined user roles

network-admin

Parameters

start-ip-address: Specifies the start IP address of the scanning range.

end-ip-address: Specifies the end IP address of the scanning range. The end IP address must be higher than or equal to the start IP address.

Usage guidelines

CAUTION:

ARP scanning will take some time and occupy a lot of system and network resources. To stop an ongoing scan, press Ctrl + C. Dynamic ARP entries are created based on ARP replies received before the scan is terminated.

ARP scanning automatically creates ARP entries for devices in the specified address range. IP addresses already in existing ARP entries are not scanned.

If the interface's primary and secondary IP addresses are in the address range, the sender IP address in the ARP request is the address on the smallest network segment.

If no address range is specified, the device learns ARP entries for devices on the subnet where the primary IP address of the interface resides. The sender IP address in the ARP requests is the primary IP address of the interface.

The start and end IP addresses must be on the same subnet as the primary IP address or secondary IP addresses of the interface.

Examples

# Configure the device to scan the neighbors on the network where the primary IP address of VLAN-interface 2 resides.

<Sysname> system-view

[Sysname] interface vlan-interface 2

[Sysname-Vlan-interface2] arp scan

# Configure the device to scan neighbors in an address range.

<Sysname> system-view

[Sysname] interface vlan-interface 2

[Sysname-Vlan-interface2] arp scan 1.1.1.1 to 1.1.1.20

arp scan auto enable

Use arp scan auto enable to enable automatic ARP scanning in a specified address range on an interface.

Use undo arp scan auto enable to disable automatic ARP scanning on an interface.

Syntax

arp scan auto enable [ start-ip-address to end-ip-address [ source-addr source-ip-address ] ]

undo arp scan auto enable

The following compatibility matrixes show the support of the device models for this command:

Series	Models	Product codes	Command compatibility
WX3500X series	WX3510X WX3520X WX3540X	EWP-WX3510X EWP-WX3520X EWP-WX3540X	Yes
WCG380 series	WCG382	EWP-WCG382	No

Series

Models

Product codes

Command compatibility

WX3500X series

WX3510X

WX3520X

WX3540X

EWP-WX3510X

EWP-WX3520X

EWP-WX3540X

Yes

WCG380 series

WCG382

EWP-WCG382

Series	Models	Product codes	Command compatibility
WX3800X series	WX3820X WX3840X	EWP-WX3820X EWP-WX3840X	Yes

Series

Models

Product codes

Command compatibility

WX3800X series

WX3820X

WX3840X

EWP-WX3820X

EWP-WX3840X

Yes

Default

Automatic ARP scanning is disabled on an interface.

Views

Layer 3 Ethernet interface view

Layer 3 Ethernet subinterface view

VLAN interface view

Predefined user roles

network-admin

Parameters

start-ip-address: Specifies the start IP address of the scanning range.

to end-ip-address: Specifies the end IP address of the scanning range. The end IP address must be higher than or equal to the start IP address. The maximum number of IP addresses in the IP range is 65535.

source-addr source-ip-address: Specifies the source address for the ARP requests. The source-ip-address argument can be any valid IP address. If you do not specify this option, the interface uses its IP address as the source address of the ARP requests.

Usage guidelines

Automatic ARP scanning enables an interface to update its ARP entries in time. It automatically sends ARP requests to the IP addresses in the specified address range to create ARP entries for them. IP addresses that already have ARP entries are not scanned any more.

If you know the IP address range assigned to the neighbors on the LAN, you can specify the assigned IP address range as the ARP scanning range to shorten the scanning waiting time.

If you specify the ARP scanning range without specifying the source address for sending ARP requests, the interface scans the IP address intersection of the scanning range and the subnet of the interface. If the interface is configured with multiple subnet addresses that intersect with the scanning range, the source address for the ARP requests is the IP address with the longest subnet mask. If the subnet masks are of the same length, the source address is the primary IP address for the interface. If all IP addresses in the scanning range are on the same subnet of the interface, the source address is that subnet IP address.

If you specify the ARP scanning range and source address for the sending ARP requests, the interface scans all IP addresses in the scanning range without considering the subnet addresses of the interface.

If the ARP scanning range is not specified, the interface scans neighbors on the subnet where the primary IP address of the interface resides. The source IP address for the ARP requests is the primary IP address for the interface.

You can set the ARP request sending rate by using the arp scan auto send-rate command.

If you trigger ARP scanning and enable automatic ARP scanning on an interface, both of them take effect. As a best practice, enable automatic ARP scanning only on networks where user come online and go offline frequently.

Examples

# Configure the device to automatically scan the neighbors on the network where the primary IP address of VLAN-interface 2 resides.

<Sysname> system-view

[Sysname] interface vlan-interface 2

[Sysname-Vlan-interface2] arp scan auto enable

Related commands

arp scan auto send-rate

Use arp scan auto send-rate to set the ARP packet sending rate for automatic ARP scanning.

Use undo arp scan auto send-rate to restore the default.

Syntax

arp scan auto send-rate { ppm ppm | pps }

undo arp scan auto send-rate

The following compatibility matrixes show the support of the device models for this command:

Series

Models

Product codes

Command compatibility

WX3500X series

WX3510X

WX3520X

WX3540X

EWP-WX3510X

EWP-WX3520X

EWP-WX3540X

Yes

WCG380 series

WCG382

EWP-WCG382

Series	Models	Product codes	Command compatibility
WX3800X series	WX3820X WX3840X	EWP-WX3820X EWP-WX3840X	Yes

Series

Models

Product codes

Command compatibility

WX3800X series

WX3820X

WX3840X

EWP-WX3820X

EWP-WX3840X

Yes

Default

The device sends ARP packets at the rate of 48 pps during automatic ARP scanning.

Views

System view

Predefined user roles

network-admin

Parameters

ppm ppm: Specifies the ARP packet sending rate, in packets per minute (ppm). The value range for the ppm argument is 10 to 600, and the value must be a multiple of 10.

pps: Specifies the ARP packet sending rate, in packets per second (pps). The value range for the pps argument is 10 to 1000, and the value must be a multiple of 10.

Usage guidelines

You can set the ARP packet sending rate if the scanning range has a large number of IP addresses. This setting can avoid high CPU usage and heavy network load caused by a burst of ARP traffic.

When you set the sending rate to a large value, the device might use a rate lower than the specified rate to ensure the device performance.

Examples

# Set the ARP packet sending rate to 10 pps during automatic ARP scanning.

<Sysname> system-view

[Sysname] arp scan auto send-rate 10

Related commands

arp scan auto enable

ARP packet sender IP address checking commands

arp sender-ip-range

Use arp sender-ip-range to specify the sender IP address range for ARP packet checking.

Use undo arp sender-ip-range to restore the default.

Syntax

arp sender-ip-range start-ip-address end-ip-address

undo arp sender-ip-range

Default

No sender IP address range is specified for ARP packet checking.

Views

VLAN view

Predefined user roles

network-admin

Parameters

start-ip-address: Specifies the start IP address.

end-ip-address: Specifies the end IP address. The end IP address must be higher than or equal to the start IP address.

Usage guidelines

The gateway discards an ARP packet if its sender IP address is not within the allowed IP address range.

If you execute this command multiple times, the most recent configuration takes effect.

Examples

# Specify the sender IP address range 1.1.1.1 to 1.1.1.20 for ARP packet checking in VLAN 2.

<Sysname> system-view

[Sysname] vlan 2

[Sysname–vlan2] arp sender-ip-range 1.1.1.1 1.1.1.20

16-Security Command Reference

display arp source-suppression

display arp detection statistics packet-drop

reset arp detection statistics packet-drop

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