show open ports ubuntu 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: check what ports are open linux

## if you use linux
sudo ss -tulw

Example 3: ubuntu open all port

sudo ufw allow 1:9999/tcp

Example 4: 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/