A computer-implemented method and device for analyzing network packet traffic flow affected by a network security device in a communication network. Received in a network monitoring device is packet traffic flow data from a network security device that filters network traffic based upon prescribed security filter settings. The network monitoring device analyzes the received packet traffic flow data by correlating the received traffic flow data with the security filter settings prescribed in the network security device. Certain statistics are identified regarding the network traffic flow affected by the security filter settings of the network security device based upon the correlating of the received traffic flow data with the security filter settings prescribed in the network security device. A report regarding the identified statistics is preferably sent to a network administrator.