Netcat

Hello GYZ!This tool goes by the name of netcat, and although well known in hacking circles, it's virtually unknown outside. It's so powerful and useful, that many people within the hacking community refer to it as the "Swiss Army knife of hacking tools."

Netcat, usually abbreviated to nc, is a network utility with which you can use TCP/IP protocols to read and write data across network connections.

You can use it to create any kind of connection as well as to explore and debug networks using tunneling mode, port-scanning, etc.

Netcat (often abbreviated to nc) is a computer networking utility for reading from and writing to network connections using TCP or UDP. Netcat is designed to be a dependable back-end 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 investigation tool, since it can produce almost any kind of connection its user could need and has a number of built-in capabilities.
Its list of features includes port scanning, transferring files, and port listening, and it can be used as a backdoor.