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Configuration Guide - Security

S1720, S2700, S5700, and S6720 V200R011C10

This document describes the configurations of Security, including ACL, local attack defense, MFF, attack defense, traffic suppression and storm control, ARP security, Port security, DHCP snooping, ND snooping, PPPoE+, IPSG, SAVI, URPF, keychain, MPAC, separating the management plane from the service plane, security risks, PKI.
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(Optional) Disabling Location Transition for DHCP Snooping Users

(Optional) Disabling Location Transition for DHCP Snooping Users


When a mobile user connects to the network through interface A, and then reconnects through interface B, the user sends a DHCP Discover message to reapply for an IP address. By default, if DHCP snooping is enabled on the device, the device allows the user to go online and updates the DHCP snooping binding entries. However, this may bring security risks. For example, if an attacker pretends to be an authorized user and sends a DHCP Discover message, the authorized user is disconnected after the DHCP snooping binding table is updated. To prevent such attacks, disable the DHCP snooping location transition function, after which the device discards the DHCP Discover messages sent by a user who has an entry in the DHCP snooping binding table (the user whose MAC address exists in the DHCP snooping binding table) if the packet is sent through another interface.


Interface A and interface B must belong to the same VLAN.


  1. Run system-view

    The system view is displayed.

  2. Run undo dhcp snooping user-transfer enable

    Location transition is disabled for DHCP snooping users.

    By default, location transition is enabled for DHCP snooping users.

Updated: 2019-09-23

Document ID: EDOC1000178177

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