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Cisco Intrusion Prevention System Appliance and Module Installation Guide for IPS 7.1
OL-24002-01
Chapter 1 Introducing the Sensor
How the Sensor Functions
•
Filter out known false positives caused by specialized software, such as vulnerability scanner and
load balancers by one of the following methods:
–
You can configure the sensor to ignore the alerts from the IP addresses of the scanner and load
balancer.
–
You can configure the sensor to allow these alerts and then use the IME to filter out the false
positives.
•
Filter the Informational alerts.
These low priority events notifications could indicate that another device is doing reconnaissance
on a device protected by the IPS. Research the source IP addresses from these Informational alerts
to determine what the source is.
•
Analyze the remaining actionable alerts:
–
Research the alert.
–
Fix the attack source.
–
Fix the destination host.
–
Modify the IPS policy to provide more information.
For More Information
•
For a detailed description of risk rating, refer to
Calculating the Risk Rating
.
•
For information on Cisco signatures, for the IDM and IME refer to
Defining Signatures
, and for the
CLI refer to
Defining Signatures.
•
For detailed information on event action overrides, for the IDM and IME refer to
Configuring Event
Action Overrides
, and for the CLI, refer to
Configuring Event Action Overrides.
Sensor Interfaces
This section describes the sensor interfaces, and contains the following topics:
•
Understanding Sensor Interfaces, page 1-4
•
Command and Control Interface, page 1-5
•
Sensing Interfaces, page 1-6
•
Interface Support, page 1-6
•
TCP Reset Interfaces, page 1-11
•
Interface Restrictions, page 1-12
Understanding Sensor Interfaces
The sensor interfaces are named according to the maximum speed and physical location of the interface.
The physical location consists of a port number and a slot number. All interfaces that are built-in on the
sensor motherboard are in slot 0, and the interface card expansion slots are numbered beginning with
slot 1 for the bottom slot with the slot numbers increasing from bottom to top (except for the
IPS 4270-20, where the ports are numbered from top to bottom). Each physical interface can be divided
in to VLAN group subinterfaces, each of which consists of a group of VLANs on that interface.