An open source software tool allowing protocol debugging, available for free.
Perhaps one of the most fascinating features of Tcpdump is that it can be run with the -w flag, the tool can save the packet data to a file for a later analysis, and/or with the -r flag that enables the program to read from a saved packet file instead of reading packets from a network interface. With this too, only packets that match the expression are processed by tcpdump.
It is noteworthy that Tcpdump will, if not run with the -c flag, continue capturing packets until it is interrupted by a SIGINT signal, typically generated by typing your interrupt character, typically control-C, or a SIGTERM signal, typically generated with the kill(1) command. Additionally, if it runs with the -c flag, the software can capture packets until it is interrupted by a SIGINT, SIGTERM signal, or the specified number of packets have been processed.
Finally, it is important to mention that Tcpdump is licensed and distributed under the terms of the BSD License, making it an open-source and flexible tool for users. In a nutshell, Tcpdump is a tool that needs to be added to the toolbox of every network administrator, protocol debugger, and data analyst to get the most out of network-specific workloads.
Version 4.0.0: N/A