H3C Technologies H3C S5560 Series Switches - Manual (Page 217)

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Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Set the maximum number
of DHCPv6 snooping
entries for the interface to
learn.
ipv6 dhcp snooping
max-learning-num number
By default, the number of DHCPv6
snooping entries for an interface to
learn is not limited.
Enabling DHCPv6-REQUEST check
Perform this task to use the DHCPv6-REQUEST check function to protect the DHCPv6 server against
DHCPv6 client spoofing attacks. Attackers can forge DHCPv6-RENEW messages to renew leases for
legitimate DHCPv6 clients that no longer need the IP addresses. The forged messages disable the victim
DHCPv6 server from releasing the IP addresses. Attackers can also forge DHCPv6-DECLINE or
DHCPv6-RELEASE messages to terminate leases for legitimate DHCPv6 clients that still need the IP
addresses.
The DHCPv6-REQUEST check function enables the DHCPv6 snooping device to check every received
DHCPv6-RENEW, DHCPv6-DECLINE, or DHCPv6-RELEASE message against DHCPv6 snooping entries.
• If any of the criteria in an entry is matched, the device compares the entry with the message
information.
{
If they are consistent, the device considers the message valid and forwards it to the DHCPv6
server.
{
If they are different, the device considers the message forged and discards it.
• If no matching entry is found, the device forwards the message to the DHCPv6 server.
To enable DHCPv6-REQUEST check:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Enable DHCPv6-REQUEST
check.
ipv6 dhcp snooping check
request-message
By default, DHCPv6-REQUEST check is
disabled.
You can enable the function only on Layer
2 Ethernet interfaces, Layer 2 aggregate
interfaces.
Configuring DHCPv6 packet rate limit
This DHCPv6 packet rate limit feature discards exceeding DHCPv6 packets to prevent attacks that send
large numbers of DHCPv6 packets.
To configure DHCPv6 packet rate limit: