ubuntu check port is open code example

Example 1: ubuntu check process on port

sudo lsof -i:22

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: see what is using a port ubuntu

$ sudo lsof -i:22