* Configures apt to use caching proxy (if any was specified).

* Sets-up umask for all logins to ``0027``.

* Installs sudo.

* Sets-up uniform bash prompt for all accounts (optionally coloured and with

  identifier). This is useful for distinguishing machines and/or environments.

* Installs additional base packages, as configured.

* Creates additional operating system groups, as configured.

* Creates additional operating system users, as configured.

* Hardens the SSH server by disabling remote ``root`` logins and password-based

  authentication.

* Allows traversing of directory ``/etc/ssl/private/`` to everyone. This lets

  you put TLS private keys in central location where any operating system user