A packet sniffer for intercepting and logging traffic on a digital network. Utilizes IP packet injection to gather information about network setup, firewall configurations, and intermediate nodes.
A packet sniffer analyses network behavior, performance and applications that generate or receive network traffic. It can also be used for analyzing the network infrastructure itself by determining whether all necessary routing is occurring properly, allowing the user to further isolate the source of a problem.
It is also possible to use a packet sniffer for the specific purpose of intercepting and displaying the communications of another user or computer. A user with the necessary privileges on a system acting as a router or gateway through which unencrypted traffic such as Telnet or HTTP passes can use tcpdump to view login IDs, passwords, the URLs and content of websites being viewed, or any other unencrypted information.