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CLI-based Configuration Guide - Security

AR500, AR510, and AR530 V200R007

This document describes the configurations of Security, including AAA, DAA,NAC, BRAS Access, ACL, Firewall, Deep Security Defense, Local Attack Defense;Attack Defense, Traffic Suppression, ARP Security, Port Security, DHCP Snooping, IPSG, URPF, PKI, SSL, HTTPS, Keychain, separating the management plane from the service plane, security risks.
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(Optional) Configuring the Device to Discard DHCP Request Messages with Non-0 GIADDR Field

(Optional) Configuring the Device to Discard DHCP Request Messages with Non-0 GIADDR Field

Context

The GIADDR field in a DHCP Request message records the IP address of the first DHCP relay agent through which the DHCP Request message passes. If the DHCP server and client are on different network segments, the first DHCP relay agent fills its own IP address in the GIADDR field before forwarding the DHCP Request message. The DHCP server then locates the DHCP client and selects an appropriate address pool to assign an IP address to the client.

To ensure that the device obtains parameters such as MAC addresses for generating a binding table, enable DHCP snooping on Layer 2 access devices or the first DHCP relay agent. Then, the GIADDR field in the DHCP Request messages received by the DHCP snooping-enabled device is 0. If the GIADDR field is not 0, the message is considered to be invalid and discarded.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Enable the device to check whether the GIADDR field in the DHCP Request message is 0 in the VLAN view or interface view.
    1. Run:

      vlan vlan-id

      The VLAN view is displayed.

      Or run:

      interface interface-type interface-number

      The interface view is displayed.

    2. Run:

      dhcp snooping check dhcp-giaddr enable

      The device is enabled to check whether the GIADDR field in a DHCP Request message is 0.

      By default, the device does not check whether the GIADDR field in a DHCP Request message is 0.

    If you run this command in the VLAN view, the command takes effect on all the DHCP messages in the specified VLAN received by all the interfaces on the device. If you run this command in the interface view, the command takes effect on all the DHCP messages received by the specified interface.

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Updated: 2019-05-25

Document ID: EDOC1000097287

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