Update your Ubuntu Server
It is good to keep any server especially once that are facing the internet up to date even Linux Machines. If you have an Ubuntu Server here are some simple commands that will help you keep you server up to date.
sudo apt-get update # Fetches the list of available updates
sudo apt-get upgrade # Strictly upgrades the current packages
sudo apt-get dist-upgrade # Installs updates (new ones)
Optional sudo apt-get autoremove