In this paper, an intelligent monitoring system for local-area network traffic is presented. The presented system sniffs the traffic on a local area network, parses the captured go-through packets and analyzes the current network traffic in a real-time manner. Thus, the developed system effectively provides the real-time traffic information for users to refer. Besides, the system offers a Web-based interface for users. Through this Web-based user interface, the authenticated users may access the information about active host physical address, IP address and opened TCP ports. Based on this real-time information, network users are accurately aware of the current network traffic, reduce the management effort and enhance the network administration performance. All software components employed in the implementation are based on open sources, including ARP, TCPDUMP and CronTab. Thus the feasibility of this presented system is confirmed.