Appnr

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.