With recent technologies, the growing network is highly increased.The number of the network user is rapidly increasing day by day which reflects the growth of network traffic also. So it’s very important to monitor networks traffic as well as its user’s activities to keep the network smooth and efficient. For a large network, it’s very complicated task to monitor the network because a large number of packets are available. For this purpose packet sniffing is used. Packet sniffing is important in network monitoring to watch network activities which help network administrators to find out the weakness of network. This paper focuses on sniffing network traffic working in the different environment. Working of Network sniffing tool Wireshark.By using this packet sniffer we can capture traffic as well as we analyzed capture traffic. We can generate reports on the basis of analyzed traffic. Many protocols like TCP, IP, UDP etc. are implemented and filtering on basis of protocol is also done. Alerts generated on the occurring of suspected activities.