Enabling Dhcp Starvation Attack Protection - HP 6125G Configuration Manual

To configure DHCP snooping entries backup:
Step
1. Enter system view.
2. Specify the name of the file for
storing DHCP snooping
entries.
3. Back up DHCP snooping
entries to the file.
4. Set the interval at which the
DHCP snooping entry file is
refreshed.

Enabling DHCP starvation attack protection

A DHCP starvation attack occurs when an attacker constantly sends forged DHCP requests using
different MAC addresses in the chaddr field to a DHCP server. This exhausts the IP address resources of
the DHCP server so legitimate DHCP clients cannot obtain IP addresses. The DHCP server may also fail
to work because of exhaustion of system resources. You can protect against starvation attacks in the
following ways:
To relieve a DHCP starvation attack that uses DHCP packets encapsulated with different source
•
MAC addresses, you can limit the number of MAC addresses that a Layer 2 port can learn.
• To prevent a DHCP starvation attack that uses DHCP requests encapsulated with the same source
MAC address, enable MAC address check on the DHCP snooping device. With this function
enabled, the DHCP snooping device compares the chaddr field of a received DHCP request with
the source MAC address field of the frame. If they are the same, the request is considered valid and
forwarded to the DHCP server. If not, the request is discarded.
Enable MAC address check only on Layer 2 Ethernet ports and Layer 2 aggregate interfaces.
To enable MAC address check:
Step
1. Enter system view.
2. Enter interface view.
3. Enable MAC address check.
Command
system-view
dhcp-snooping binding
database filename filename
dhcp-snooping binding
database update now
dhcp-snooping binding
database update interval
minutes
Command
system-view
interface interface-type
interface-number
dhcp-snooping check mac-address
55
Remarks
N/A
Not specified by default.
DHCP snooping entries are stored
immediately after this command is
used and then updated at the
interval set by the dhcp-snooping
binding database update interval
command.
Optional.
DHCP snooping entries will be
stored to the file each time this
command is used.
Optional.
By default, the file is not refreshed
periodically.
Remarks
N/A
N/A
Disabled by default