linux see open port code example
Example 1: how to check list of open ports in linux
sudo lsof -i -P -n | grep LISTEN
sudo netstat -tulpn | grep LISTEN
sudo lsof -i:22 # see a specific port such as 22
sudo nmap -sTU -O IP-address-Here
Example 2: linux see used ports
netstat -tulpn
Example 3: check what ports are open linux
## if you use linux
sudo ss -tulw