Netcat is a featured networking utility which reads and writes 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.