The threats and intrusions in IT systems can basically be compared to human diseases with the difference that the human body has an effective way to deal with them, what still need to be designed for IT systems. The human immune system (HIS) can detect and defend against yet unseen intruders, is distributed, adaptive and multilayered to name only a few of its features. Our immune system incorporates a powerful and diverse set of characteristics which are very interesting to use in the design of Intrusion Detection Systems (IDS). The authors propose therefore a hybrid intrusion detection system which combines host based and network based components but giving the focus to the host based intrusion detection as it is similar to the HIS. The proposed intrusion detection system will use the concepts of the artificial immune systems (AIS) which is a promising biologically inspired computing model based on the HIS. This paper presents an intrusion detection system based on the model of the h...