H3C MSR Series Command Reference

1084
Predefined user roles
network-admin
Parameters
threshold-value: Specifies the threshold value. The value range is 1 to 1000000 in units of SYN-ACK
packets sent to an IP address per second.
Usage guidelines
The global threshold applies to global SYN-ACK flood attack detection. Adjust the threshold
according to the application scenarios. If the number of SYN-ACK 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.
With global SYN-ACK flood attack detection configured, the device is in attack detection state. When
the sending rate of SYN-ACK 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.
Examples
# Set the global threshold to 100 for triggering SYN-ACK flood attack prevention in the attack
defense policy atk-policy-1.
<Sysname> system-view
[Sysname] attack-defense policy atk-policy-1
[Sysname-attack-defense-policy-atk-policy-1] syn-ack-flood threshold 100
Related commands
syn-ack-flood action
syn-ack-flood detect
syn-ack-flood detect non-specific
syn-flood action
Use syn-flood action to specify global actions against SYN flood attacks.
Use undo syn-flood action to restore the default.
Syntax
syn-flood action { client-verify | drop | logging } *
undo syn-flood action
Default
No global action is specified for SYN flood attacks.
Views
Attack defense policy view
Predefined user roles
network-admin
Parameters
client-verify: Adds the victim IP addresses to the protected IP list for TCP client verification. If TCP
client verification is enabled, the device provides proxy services for protected servers.
drop: Drops subsequent SYN packets destined for the victim IP addresses.

H3C MSR Series Specifications

General

Category	Network Router
IPv6 Support	Yes
Dimensions	Varies by model
Weight	Varies by model
Product Type	Modular Router
Ports	Varies by model
WAN Interfaces	Varies by model
Firewall	Yes
QoS	Yes
Wireless Support	Varies by model
USB Ports	Varies by model
Console Port	Yes
Power Supply	Varies by model
Redundancy	Varies by model
Operating Temperature	0°C to 45°C
Storage Temperature	-40°C to 70°C
Humidity	5% to 95% non-condensing
Series	MSR
Certifications	CE, FCC, RoHS