slackbuilds/network/netcat

GNU 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.