Abstract: System for facilitating detection of network intrusion. Through continuous accumulation of network traffic parameter information, data for a particular session is reduced to a single metric that represents the threat potential of the session as compared to normal network traffic. An analysis station accumulates and maintains the historical data and defines a point for each specific session within a distribution. The dimensions in the distribution space take into account various network traffic parameters useful in identifying an attack. The distance between a session's point and the centroid of the distribution represents the threat metric. The analysis station can display the threat metric as a point or points on a display. The intensity of the point is an indication of the threat potential. The easy-to-read display calls anomalous traffic to the attention of an operator and facilitates discrimination among ambiguous cases.