cisco certification devnet

cisco certification devnet.first simply consider the behavior of systems and applications as normal, and then categorize those systems and applications as heuristic-based.However, sometimes it is not easy to categorize a particular behavior as normal or abnormal based on various factors such asThe negotiated protocol and port number.Variations in the particular application.Changes in network architecture.There is a "variant" of the anomaly-based analysis method called profile-baseddetection.A variation on the anomaly-based analysis approach is called profile-baseddetection. The NIDS performing this detection method can also adjust the alert messages it generates when certain systems and end users change the way they communicate within the network. There is another anomaly-based detection method called protocol-based detection. This detection method involves a protocol decoding method that132 Chapter 2 Network Security Appliances and Cloud Servicesbut it is important not to confuse the two methods. In contrast to the protocol decoding method, the protocol-based detection method relies on a well-defined protocol, and the NIDS performing the method classifies any volatile or configurable values in the relevant protocol header fields as anomalies. For example, a cache overflow is considered to be detected when a specific string is identified within the net load of the IP packet being detected.Tip: A cache overflow occurs when a program stores more data in a temporary storage area of memory (cache) than it was designed for. This may allow data to incorrectly overflow into an adjacent memory area. An attacker can take the opportunity to insert his own carefully constructed special data into the adjacent buffer. Thereafter, when the system reads this special data, new instructions and malicious commands are executed.