Netcat

Netcat is a network utility for interacting with TCP/UDP ports. It’s primarily used for connecting to shells. Generally speaking, it is used to connect to a listening port and interact with the service running on that port. It can also be used to transfer files.

Socat is another tool that has features Netcat doesn’t support like port forwarding and connecting to serial devices. It can also be used to upgrade a shell to a fully interactive “TTY”.

nc -nv has the same affect as the nmap -sV --script=banner command.