ubuntu display open 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: ubuntu open port

sudo ufw allow 1191/tcp

Example 3: 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 4: netstat command in linux to check specific port

netstat -tulpn | grep :80

Example 5: ubuntu open all port

sudo ufw allow 1:9999/tcp