Debian: download and install security upgrades automatically

To improve the situation with the Security Server, a good idea is to install security updates automatically. In order to ensure that security updates are posted automatically, you need an unattended-upgrades package.

unattended-upgrades package can download and install security upgrades automatically and unattended, taking care to only install packages from the configured APT source, and checking for dpkg prompts about configuration file changes.

This script is the backend for the APT::Periodic::Unattended-Upgrade option.

1. Install unattended-upgrades package
   apt–get install unattended–upgrades
2. Configure this package
   dpkg–reconfigure unattended–upgradesIn this setting Automatic Security Updates over.