Huawei Quidway S5600 Series Operation Manual page 673

Operation Manual - DHCP
Quidway S5600 Series Ethernet Switches-Release 1510
When DHCP is enabled, sockets UDP 67 and UDP 68 used by DHCP are enabled.
When DHCP is disabled, sockets UDP 67 and UDP 68 are disabled at the same
time.
The preceding functions are implemented as follows:
After you configure a DHCP server group by using the dhcp-server command,
sockets UDP 67 and UDP 68 will be enabled.
After you delete the DHCP server group by using the undo dhcp-server command
and disable all the DHCP functions, sockets UDP 67 and UDP 68 will be disabled.
3.2.4 Configuring DHCP Relay Security
I. Configuring address checking
When a DHCP client obtain an IP address from a DHCP server with the help of a
DHCP relay, the DHCP relay creates an entry (dynamic entry) in the user address
table to track the IP-MAC address binding information about the DHCP client. You can
also configure user address entries manually (static entries) to bind an IP address and
a MAC address statically.
The purpose of the address checking function on DHCP relay is to prevent
unauthorized users from statically configuring IP addresses to access external
networks. With this function enabled, a DHCP relay inhibits a user from accessing
external networks if the IP address configured on the user end and the MAC address
of the user end do not match any entries (including the entries dynamically tracked by
the DHCP relay and the manually configured static entries) in the user address table
on the DHCP relay.
Table 3-4 Configure address checking
Operation
Enter system view
Create a DHCP user
address
manually
Enter interface view
Enable
checking function
system-view
dhcp-security
entry
ip-address mac-address
interface
interface-number
the address
address-check enable
Huawei Technologies Proprietary
Chapter 3 DHCP Relay Configuration
Command
—
Optional
static
By default, no DHCP user
address entry is configured
interface-type
—
Required
By
checking function is disabled
3-6
Description
default, the address