Netcat
In computing, netcat is a network utility for reading from and writing to network connections on either TCP or UDP. It is designed in a thin and simple way, which makes it easy to incorporate in larger applications. Because of its versatility, netcat is also called the "TCP/IP Swiss Army Knife".
The original version of netcat is a UNIX program. Its author is known only as *hobbit*. A Windows version of netcat was created by Chris Wysopal.