Netcat

Netcat is a utility tool that is used for a variety of issues related to TCP or UDP protocol. That can open TCP connections, send UDP paketpaket, listen on TCP and UDP ports, do port scanning, and in accordance with IPV4 and IPV6. Unlike telnet, nc scripts separates error messages onto standard error instead of to standard output, while telnet to send the output and standard error to the same output.

Netcat is usually used by the hacker or hackers to connect back to the target system so that hackers gain root access via the port who have been determined by the hacker.