For massive data such as network traffic, DBSCAN has weakness of greatly time consuming, it has poor clustering effect for some network protocol as well. In the context of network traffic classification via HMM, an improved DBSCAN algorithm is put forward. The algorithm improves the time efficiency and accuracy by reducing the time of querying. The improved algorithm is used to construct the HMM of network traffic automatically based on the divided-andconquer strategy. The experimental result shows that the...