CHAPTER 16CISCO IOS IPS

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SECURING NETWORKS WITH IDS AND IPS

Intrusion Detection System (IDS) and Intrusion Prevention System (IPS) sensors protect your network from malicious traffic. The two systems are deployed differently and scan for malicious traffic in different ways. Each system has strengths and weaknesses when deployed separately, but when used together, IDS and IPS can provide a much richer and deeper level of security

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BASIC FUNCTIONS OF THE INTRUSION DETECTION SYSTEM (IDS)

IDS is typically characterized as a passive listening device. This label is given to these systems because traffic does not have to pass through the system; IDS sensors listen promiscuously to all traffic on the network

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BASIC FUNCTIONS OF THE INTRUSION PREVENTION SYSTEM (IPS)

IPS is characterized as an active device. This is because the device is implemented as an inline sensor. The IPS requires the use of more than one interface, and all traffic must pass through the sensor. Network traffic enters through one interface and exits through another

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USING IDS AND IPS TOGETHER

When you think about having one or the other of these sensors on your network, think about the benefits you would get from having both. An IPS sensor is much like a firewall; it can block traffic that is malicious or threatening. It should only block traffic that is known to be a threat, though. IPS should not block legitimate traffic or you could suffer a disruption in legitimate connectivity and find that applications are unable to perform their tasks

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BENEFITS AND DRAWBACKS OF IPS/IDS SENSORS A network-based monitoring system has the

benefit of easily seeing attacks that are occurring across the entire network

Encryption of the network traffic stream can effectively blind the sensor. Reconstructing fragmented traffic can also be a difficult problem to solve

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TYPES OF IDS AND IPS SENSORS

Network Based (NIPS,NIDS)

Host Based (HIPS,HIDS)

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NETWORK BASED INTRUSION PREVENTION SYSTEM (NIPS) Network-based sensors examine packets and

traffic that are traversing through the network for known signs of malicious activity. Because these systems are watching network traffic, any attack signatures detected may succeed or fail. It is usually difficult, if not impossible, for network-based monitoring systems to assess the success or failure of the actual attacks

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HOST BASED INTRUSION PREVENTION SYSTEM(HIPS) A host-based sensor examines information at

the local host or operating system. The HIPS has full access to the internals of the end station, and can relate incoming traffic to the activity on the end station to understand the context. Host-based sensors can be implemented to a couple of different complexity levels

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MALICIOUS TRAFFIC IDENTIFICATION APPROACHES

Signature-based

Policy-based

Anomaly-based

Honeypot

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SIGNATURE TYPES

Exploit signatures

Connection signatures

String signatures

DoS signatures

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IPS ALARMS

An IPS sensor can react in real time when a signature is matched. This allows the sensor to act before network security has been compromised. The sensor can optionally log whatever happened with a syslog message or Security Device Event Exchange (SDEE)

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CONFIGURING IOS IPS

It is now time to look at the configuration of IOS IPS. This section takes you through the configuration process using the SDM interface. The SDM gives you quite a few configuration capabilities for IOS IPS. You can configure every option through the IPS Edit menu

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SDM HOME SCREEN

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DEFAULT CONFIGURATION SCREEN

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DEFAULT IPS SCREEN

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SDEE ENABLE NOTIFICATION

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IPS WIZARD WELCOME SCREEN

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SELECT INTERFACES SCREEN

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SDF LOCATIONS SCREEN

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ADD A SIGNATURE LOCATION DIALOG BOX

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SDF LOCATIONS WITH FILE ADDED

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WIZARD SUMMARY PAGE

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SUMMARY