Abstract This paper presents a new passive technique for estimating the bottleneck bandwidth based on transferring the Gaussian kernel density estimation of the packets inter-arrival times to the frequency domain. The resulting spectrum contains information about the transmission time of the bottleneck link and can reveal information about multiple bottlenecks if they exist along the end-to-end path. The advantage of the technique is that it provides a model that can be manipulated by the digital signal processing methods and, unlike prior work in the area, it relies less on statistical methods. The proposed technique was validated using the ns2 network simulator [1] on several topologies and traffic sources. Further experiments were conducted to test the strength of the patterns between flows that share a bottleneck by applying K-means algorithm to cluster the average packet inter-arrival times of these flows. The paper also presents a set of results from real traffic experiments conducted in order to infer both the bottleneck bandwidth and the capacity of the path using a passive approach.