linux commands: Used ports

used-ports.sh

# To check the listening ports and applications on Linux:

# Open a terminal application i.e. shell prompt.
# Run any one of the following command on Linux to see open ports:
sudo lsof -i -P -n | grep LISTEN
sudo netstat -tulpn | grep LISTEN
sudo ss -tulpn | grep LISTEN
sudo lsof -i:22 ## see a specific port such as 22 ##
sudo nmap -sTU -O IP-address-Here

# For the latest version of Linux use the ss command. For example: 
ss -tulw