09-Security Configuration Guide

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12-Attack detection and prevention configuration

Configuring attack detection and prevention


Attack detection and prevention enables a device to detect attacks by inspecting arriving packets, and to drop attack packets to protect a private network.

The device supports only TCP fragment attack prevention.

Enabling TCP fragment attack prevention

The TCP fragment attack prevention feature takes effect only on Layer 3 packets.

This feature enables the device to drop attack TCP fragments to prevent TCP fragment attacks that traditional packet filter cannot detect. As defined in RFC 1858, attack TCP fragments refer to the following TCP fragments:

·          First fragments in which the TCP header is smaller than 20 bytes.

·          Non-first fragments with a fragment offset of 8 bytes (FO=1).

To enable TCP fragment attack prevention:





1.       Enter system view.



2.       Enable TCP fragment attack prevention.

attack-defense tcp fragment enable

By default, TCP fragment attack prevention is enabled.


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