Defense in depth is a security strategy that involves using multiple layers of security controls to protect a system or network. Each layer of defense is designed to prevent or mitigate different types of threats, and if one layer is breached, the other layers can still provide protection.
Here is a diagram that illustrates the concept of defense in depth:
+-----------------------+
| Application Controls |
+-----------------------+
| Network Segmentation |
+-----------------------+
| Host-based IDS |
+-----------------------+
| Firewalls |
+-----------------------+
| Physical Security |
+-----------------------+
In this diagram, each layer of defense represents a different security control:
- Physical Security: Physical security measures such as security cameras, access controls, and guards to protect physical assets like servers, routers, and switches.
- Firewalls: Firewalls that can filter traffic and block unauthorized access to the network.
- Host-based IDS: Intrusion detection systems installed on individual hosts to detect and prevent attacks at the host level.
- Network Segmentation: The network is segmented into different subnets to limit the spread of attacks across the network.
- Application Controls: Application-level controls such as access controls, input validation, and encryption to protect against application-level attacks.
By implementing multiple layers of defense, a system or network can remain secure even if one layer of defense is breached.
