Interface Parameter Settings

On a network with DHCP configured, attackers can take many methods to attack a network. You can configure DHCP snooping to prevent DHCP attacks.

Context

After the DHCP snooping basic function is configured on a switch, the switch ensures that DHCP clients obtain IP addresses from authorized DHCP servers. This function effectively prevents bogus DHCP server attack. On a network with DHCP configured, attackers can take many methods to attack a network. You can configure DHCP snooping to prevent DHCP attacks.

Procedure

Set interface parameters.

Choose Security > DHCP Snooping > Interface Parameter Settings in the navigation tree to open the Interface Parameter Settings page

Table 1 describes the parameters on the page.

**Table 1** Interface Parameter Settings
Parameter		Description
Interface Name		Indicates the name of the interface.
Packet Rate Limiting		Indicates whether the function of detecting the rate of DHCP packets sent to the DHCP module is enabled.
Packet Rate Alarm		Indicates that an alarm is sent when the number of discarded DHCP packets reaches the limit.
Alarm Threshold (packets)		Indicates the alarm threshold for DHCP packet discarding. When the number of discarded DHCP packets reaches this threshold, an alarm is reported.
Lease Extending Check		Indicates whether the function of checking DHCP packets against binding table is enabled.
Lease Extending Alarm		Indicates whether the alarm function for DHCP packets discarded in binding table check is enabled.
Alarm Threshold (packets)		Indicates the alarm threshold for DHCP packet discarding. When the number of discarded DHCP packets reaches this threshold, an alarm is reported.
CHADDR Check		Indicates the function of comparing the source MAC address in DHCP Request packet header with the CHADDR field.
CHADDR Alarm		CHADDR alarm is reported when the number of packets discarded in CHADDR field check reaches the alarm threshold.
Alarm Threshold (packets)		When the number of packets discarded in CHADDR field check reaches this alarm threshold, the device generates a CHADDR alarm.

Select interfaces and click Configure to open the Interface Parameter Settings page

Table 2 describes the parameters on the page.

**Table 2** Interface Parameter Settings on Specified Interface
Parameter		Description
Interface name		Indicates the interface where the DHCP snooping function will be configured.
Packet rate limiting		Indicates the packet rate limiting function on the interface, including enabled and disabled.
Packet rate alarm		Indicates the packet rate limiting alarm on the interface, including enabled and disabled.
Alarm threshold		Indicates the packet rate alarm threshold.
Lease extending check		Indicates the status of the lease extending check function, including enabled and disabled.
Lease extending alarm		Indicates the status of lease extending check alarm, including enabled and disabled.
Alarm threshold		Indicates the lease extending alarm threshold.
CHADDR check		Indicates the status of CHADDR check function, including enabled and disabled.
CHADDR alarm		Indicates the status of CHADDR alarm function, including enabled and disabled.
Alarm threshold		Indicates the CHADDR alarm threshold.

Set the required parameters.
Click OK.

Update interface parameters.
1. Choose Security > DHCP Snooping > Interface Parameter Settings in the navigation tree to open the Interface Parameter Settings page.
2. Click Refresh.
Query interface parameters.
1. Choose Security > DHCP Snooping > Interface Parameter Settings in the navigation tree to open the Interface Parameter Settings page.
2. In the Query area, select an interface type and enter the interface number, and click Query.