Abstract: It is not possible to detect all the security attacks together. The detection that is available is on various platforms. This in turn exploits security problems which are way too difficult and expensive to resolve. The integrity, availability and confidentiality of a system is compromised by an intrusion. The Intrusion Detection System (IDS) is used to detect such intrusions in a network. For this the Data Mining is integrated with the IDS to detect such intrusions. Algorithms such as EDADT algorithm, varying HOPERAA algorithm, Hybrid IDS model, and semi supervised approach are used for detection of such attacks. All the algorithms are quite accurate and false alarm rate is reduced

Keywords: Anomaly based algorithm, classification algorithm, data communication, Denial of Service attack, Intrusion Detection, EDADT algorithm, HOPERAA algorithm, hybrid IDS model, semi-supervised approach