Netcat is a featured networking utility which reads and writees data across network connections, using the TCP/IP protocol. It is designed to be a reliable "back-end" tool that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and exploration tool, since it can create almost any kind of connection you would need and has several interesting built-in capabilities.
Platform: Linux/BSD;License: GNU General Public License v3
Reference: https://sourceforge.net/projects/netcat/