Dhcp Server Screening; Dhcp Server Screening Port Settings - D-Link xStack DGS-3420 Series Reference Manual

xStack® DGS-3420 Series Layer 2 Managed Stackable Gigabit Switch Web UI Reference Guide

DHCP Server Screening

This function allows the user to not only to restrict all DHCP Server packets but also to receive any specified DHCP
server packet by any specified DHCP client, it is useful when one or more DHCP servers are present on the
network and both provide DHCP services to different distinct groups of clients.
The first time the DHCP filter is enabled it will create both an access profile entry and an access rule per port entry,
it will also create other access rules. These rules are used to block all DHCP server packets. In addition to a permit
DHCP entry it will also create one access profile and one access rule entry the first time the DHCP client MAC
address is used as the client MAC address. The Source IP address is the same as the DHCP server's IP address
(UDP port number 68). These rules are used to permit the DHCP server packets with specific fields, which the user
has configured.
When DHCP Server filter function is enabled all DHCP Server packets will be filtered from a specific port.

DHCP Server Screening Port Settings

The Switch supports DHCP Server Screening, a feature that denies access to rogue DHCP servers. When the
DHCP server filter function is enabled, all DHCP server packets will be filtered from a specific port.
To view this window, click Security > DHCP Server Screening > DHCP Server Screening Port Settings as
shown below:
The fields that can be configured are described below:
Parameter
DHCP Server Screening
Trap Log State
Illegal Server Log
Suppress Duration
Unit
From Port / To Port
State
Figure 8-61 DHCP Server Screening Port Settings window
Description
Enable or disable this feature.
Choose an illegal server log suppress duration of 1 minute, 5 minutes, or 30
minutes.
Select the unit you wish to configure.
A consecutive group of ports may be configured starting with the selected port.
Choose Enabled to enable the DHCP server screening or Disabled to disable it.
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