syn-flood threshold

Use syn-flood threshold to set the global threshold for triggering SYN flood attack prevention.

Use undo syn-flood threshold to restore the default.


syn-flood threshold threshold-value

undo syn-flood threshold


The global threshold is 1000 for triggering SYN flood attack prevention.


Attack defense policy view

Predefined user roles




threshold-value: Specifies the threshold value. The value range is 1 to 1000000 in units of SYN packets sent to an IP address per second.

Usage guidelines

With global SYN flood attack detection configured, the device is in attack detection state. When the sending rate of SYN packets to an IP address reaches the threshold, the device enters prevention state and takes the specified actions. When the rate is below the silence threshold (three-fourths of the threshold), the device returns to the attack detection state.

The global threshold applies to global SYN flood attack detection. Adjust the threshold according to the application scenarios. If the number of SYN packets sent to a protected server, such as an HTTP or FTP server, is normally large, set a large threshold. A small threshold might affect the server services. For a network that is unstable or susceptible to attacks, set a small threshold.


# Set the global threshold to 100 for triggering SYN flood attack prevention in attack defense policy atk-policy-1.

<Sysname> system-view
[Sysname] attack-defense policy atk-policy-1
[Sysname-attack-defense-policy-atk-policy-1] syn-flood threshold 100

Related commands

syn-flood action

syn-flood detect

syn-flood detect non-specific