Data mining techniques have been successfully applied in almost all the fields including process control, marketing, manufacturing, fraud detection and network management. Over the past few years, a growing number of research projects have applied data mining techniques to various problems in intrusion detection. In information security, intrusion detection is the act of detecting actions that attempt to compromise the three pillars of network security such as confidentiality, data integrity and resource availability. Intrusion detection does not, in general, include prevention of intrusions. In this paper, the authors mostly focus on data mining techniques that are being used for such purposes. Finally they present a new idea on how data mining can be applied to detect the intrusions.