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Cisco Intrusion Prevention System CLI Sensor Configuration Guide for IPS 7.1
OL-19892-01
Chapter 9 Configuring Anomaly Detection
Configuring the Illegal Zone
Configuring TCP Protocol for the Illegal Zone
Use the tcp {enabled | dst-port number | default-thresholds} command in service anomaly detection
illegal zone submode to enable and configure the TCP service. The following options apply:
• enabled {false | true}—Enables/disables TCP protocol.
• default-thresholds—Defines thresholds to be used for all ports not specified in the destination port
map:
–
threshold-histogram {low | medium | high} num-source-ips number—Sets values in the
threshold histogram.
–
scanner-threshold—Sets the scanner threshold. The default is 200.
• dst-port number—Defines thresholds for specific destination ports. The valid values are 0 to 65535.
• enabled {true | false}—Enables/disables the service.
• override-scanner-settings {yes | no}—Lets you override the scanner values:
–
threshold-histogram {low | medium | high} num-source-ips number—Sets values in the
threshold histogram.
–
scanner-threshold—Sets the scanner threshold. The default is 200.
Configuring the Illegal Zone TCP Protocol
To configure TCP protocol for illegal zone, follow these steps:
Step 1 Log in to the CLI using an account with administrator privileges.
Step 2 Enter anomaly detection illegal zone submode.
sensor# configure terminal
sensor(config)# service anomaly-detection ad0
sensor(config-ano)# illegal-zone
sensor(config-ano-ill)#
Step 3 Enable TCP protocol.
sensor(config-ano-ill)# tcp
sensor(config-ano-ill-tcp)# enabled true
Step 4 Associate a specific port with TCP protocol.
sensor(config-ano-ill-tcp)# dst-port 20
sensor(config-ano-ill-tcp-dst)#
Step 5 Enable the service for that port.
sensor(config-ano-ill-tcp-dst)# enabled true
Step 6 Override the scanner values for that port. You can use the default scanner values, or you can override
them and configure your own scanner values.
sensor(config-ano-ill-tcp-dst)# override-scanner-settings yes
sensor(config-ano-ill-tcp-dst-yes)#
Step 7 Add a histogram for the new scanner settings. Enter the number of destination IP addresses (low,
medium, or high) and the number of source IP addresses you want associated with this histogram.
sensor(config-ano-ill-tcp-dst-yes)# threshold-histogram low num-source-ips 100