This module is meant primarily for "paranoid" Drupal use cases involving information warfare. Typical users might be political dissidents in repressive regimes, BitTorrent bootleggers, various kinds of activists, and so on and so forth.
Basically, if you have adversaries trying to hunt & shut your site down or limit your ability to disseminate information, you'll probably want to install Lockdown to help maintain tight information discipline as well as to guard the perimeter and perhaps give you some advance warning when it's getting to be time to move shop.
- Lockdown levels are a measure of the level of alertness and the general state of readiness to respond to threats posed by adversaries seeking to disrupt normal activities. Levels implement and enforce configurable lockdown policies and their activation can be triggered automatically through Rules events.
- Lockdown policies are implemented as part of lockdown levels, and can be used to determine e.g. how accessible the Drupal site is to anonymous visitors (including web crawlers specifically) and what the data retention times are for access logs and other personally identifying information.
- Lockdown rules can be configured for each lockdown level and executed automatically when that level is activated, taking precautionary actions, such as notifying administrators, or defensive measures such as immediately scrubbing the database of any personally identifying information, executing pre-configured shell/SQL/PHP commands, or even erasing the Drupal database altogether.