Computer Basics - Demilitarized Zo

A Demilitarized Zone (DMZ) in networking is an isolated network segment that hosts public-facing services (such as web servers, email servers, or DNS servers), while keeping the internal corporate network protected.

Purpose of a DMZ:

• Acts as a buffer zone between the internet (untrusted) and the internal network (trusted).

• Ensures that if a public-facing service is compromised, attackers cannot directly access the internal network.

• Provides an additional layer of defense in depth.

How It Works:

• Public services (web servers, mail servers, FTP servers) are placed in the DMZ.

• Firewalls (or similar controls) are used to strictly control:

  • Inbound traffic → from the internet to the DMZ only.

  • Outbound traffic → from the DMZ to the internet if required.

  • Limited traffic → between the DMZ and the internal LAN.

Example:

• Without DMZ: A web server is placed directly inside the internal LAN → if hacked, the whole network is at risk.

• With DMZ: The web server is isolated in the DMZ → even if compromised, attackers cannot easily reach sensitive internal resources.

Benefits:

• Reduces the attack surface.

• Segregates public services from private systems.

• Adds layered security for critical assets.

Typical Setup:

• Firewall 1: Between internet and DMZ → allows only necessary inbound connections (e.g., HTTPS).

• Firewall 2: Between DMZ and internal LAN → allows only specific, controlled communication (e.g., database queries to an internal server).

Would you like me to also create a simple diagram of a DMZ architecture to make this clearer?