Defense In Depth

The concept behind the Defense in Depth strategy is to protect a system against an array of attacks using various methods. It is essentially a layering tactic, originally conceived by the NSA (National Security Agency) as a comprehensive method of securing electronic information. Defense in Depth was first used as a military strategy to delay, rather than completely prevent a specific attack. This was done by yielding space in order to buy extra time for preparation. The implementation of procedures, policies and various mechanisms describes the modern usage of Defense in Depth. This is done to increase the security and reliability of an IT system in which multiple layers of protection are designed to prevent attacks. Examples of Defense in Depth: physical security (dead bolt locks), authentication-based security, anti-virus software, firewall (software of hardware), proxy servers), demilitarized zones (perimeter networks), packet filters, switches and routers, VPN (virtual private networks), timed access control, biometrics.