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Operation Manual - DHCP
Quidway S5600 Series Ethernet Switches-Release 1510
Chapter 3 DHCP Relay Configuration
Huawei Technologies Proprietary
3-6
z
When DHCP is enabled, sockets UDP 67 and UDP 68 used by DHCP are enabled.
z
When DHCP is disabled, sockets UDP 67 and UDP 68 are disabled at the same
time.
The preceding functions are implemented as follows:
z
After you configure a DHCP server group by using the
dhcp-server
command,
sockets UDP 67 and UDP 68 will be enabled.
z
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
Command
Description
Enter system view
system-view
—
Create a DHCP user
address entry
manually
dhcp-security static
ip-address
mac
-
address
Optional
By default, no DHCP user
address entry is configured
Enter interface view
interface
interface-type
interface-number
—
Enable the address
checking function
address-check enable
Required
By default, the address
checking function is disabled