ubuntu list ports\ code example

Example 1: ubuntu listening ports

# To see ports in use
sudo lsof -i -P -n | grep LISTEN 
sudo netstat -tulpn | grep LISTEN

Example 2: check all running ports ubuntu

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

# Source
https://www.cyberciti.biz/faq/unix-linux-check-if-port-is-in-use-command/