Example tcpdump Command The expression identifies which packets to capture, and the options define, in part, how those packets are displayed as well as other aspects of program behavior.

You can also specify a source or destination port using similar commands. In the example below, we use tcpdump to collect traffic heading to a local web server.

Part I of this article discussed tcpdump, a command-line utility that sniffs network traffic. Now let's see what it can do. Scenario 1: Established Telnet Connection Using tcpdump we can analyze the ...