TCP/IP swiss army knife

 A simple Unix utility which reads and writes data across network
 connections using TCP or UDP 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.
 .
 This is the "classic" netcat, written by *Hobbit*. It lacks many
 features found in netcat-openbsd.