886
Predefined user roles
network-admin
Parameters
threshold-value
: Specifies the threshold value. The value range is 1 to 1000000 in units of DNS
packets sent to an IP address per second.
Usage guidelines
The global threshold applies to global DNS flood attack detection. Adjust the threshold according to
the application scenarios. If the number of DNS packets sent to a protected DNS 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 DNS flood attack detection configured, the device is in attack detection state. When the
sending rate of DNS 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 DNS 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] dns-flood threshold 100
Related commands
dns-flood action
dns-flood detect
dns-flood detect non-specific
exempt acl
Use
exempt acl
to configure attack detection exemption.
Use
undo exempt acl
to restore the default.
Syntax
exempt acl
[
ipv6
] {
acl-number
|
name
acl-name
}
undo exempt acl
[
ipv6
]
Default
Attack detection exemption is not configured.
Views
Attack defense policy view
Predefined user roles
network-admin
Parameters
ipv6
: Specifies an IPv6 ACL. To specify an IPv4 ACL, do not use this keyword.
acl-number
: Specifies an ACL by its number:
•
2000 to 2999 for basic ACLs.
•
3000 to 3999 for advanced ACLs.