Nmap
Nmap is a network scanner created by Gordon Lyon. Nmap is used to discover hosts and services on computer network by sending packets and analyzing the responses.
Nmap provides a number of features for probing computer networks, including host discovery and service and operating system detection.
# NSE (banner grabbing)
nmap -sV -O --script=banner $IPNetcat
Netcat or nc utility is used for just about anything under the sun involving TCP or UDP.
nc -nv $IP $PORT