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Cisco Intrusion Prevention System Sensor CLI Configuration Guide for IPS 7.2
OL-29168-01
Chapter1 4 Configuring Attack Response Controller for Blocking and Rate Limiting
Disabling Blocking
Configuring Addresses Never to Block
Use the never-block-hosts and the never-block-networks commands in the service network access
submode to configure hosts and network that should never be blocked.
The following options apply:
ip_address—Specifies the IP address of the device that should never be blocked.
ip_address
/
netmask—Specifies the IP address of the network that should never be blocked. The
format is A.B.C.D/nn.
You must tune your sensor to identify hosts and networks that should never be blocked, not even
manually, because you may have a trusted network device whose normal, expected behavior appears to
be an attack. Such a device should never be blocked, and trusted, internal ne tworks should never be
blocked. You can specify a single host or an entire network.
Note
The never-block-hosts and the never-block-networks commands apply only to the Request Block Host
and Request Block Connection event actions. It does not apply to the Deny Attacker Inline, Deny
Connection Inline, or Deny Packet Inline event actions. Use event action rules to filter out the hosts that
you do not want blocked, denied, or dropped.
Configuring Addresses Never to Be Blocked
To set up addresses never to be blocked by blocking devices, follow these steps:
Step 1
Log in to the CLI using an account with administrator privileges.
Step 2
Enter network access submode.
sensor# configure terminal
sensor(config)# service network-access
sensor(config-net)#
Step 3
Enter general submode.
sensor(config-net)# general
Step 4
Specify the address that should never be blocked:
For a single host
sensor(config-net-gen)# never-block-hosts 192.0.2.1
For a network
sensor(config-net-gen)# never-block-networks 209.165.200.224/27
Step 5
Verify the settings.
sensor(config-net-gen)# show settings
general
-----------------------------------------------
log-all-block-events-and-errors: true <defaulted>
enable-nvram-write: false <defaulted>
enable-acl-logging: false <defaulted>
allow-sensor-block: false default: false
block-enable: true default: true
block-max-entries: 100 default: 250
max-interfaces: 250 <defaulted>
master-blocking-sensors (min: 0, max: 100, current: 0)