What is a Network DMZ & How does it protect my Business?

Network DMZ
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What is a network DMZ? A corporate network has different types of users ranging from stakeholders to cyber attackers accessing it on a daily basis. As a business expands and grows, it gets more challenging to identify which users you can trust.

While you may find internal business personnel to be trustworthy, you can never predict users from outside your business. An effective solution to this problem comes in the form of a DMZ or Demilitarized Zone.

Below, we take a look at DMZ and try to understand how it can help keep your business safe.

What is a DMZ?

A DMZ (Demilitarized Zone) network is essentially a subnetwork that contains all the outward-facing services of an organization. It serves as the exposed point to untrusted networks like the internet.

A DMZ is also called a perimeter network or screened subnetwork and aims to provide an extra layer of security for the organization’s local area network by blocking users from trying to access sensitive business information.

Services an organization wants to provide to users through the internet are generally placed on the DMZ network. All the external-facing services, resources, and servers, including the FTP, proxy servers, email, web, and DNS, are placed here. Users can access these services and data from the internet, but the internal LAN stays inaccessible.

Such an approach offers an additional safety layer to the local network as it blocks access to internal data and servers.

What is the Purpose of a Network DMZ?

A DMZ provides a buffer between the business’ sensitive information and the outside world. This can be particularly useful in preventing cybercriminals from gaining information through internet-facing services for future attacks.

Even if an attacker accesses the DMZ, they only access the data in that zone and keep the sensitive data safe and protected.

Demilitarized zones have a zero-trust policy, meaning everything is identified as untrusted and requires trust to work. So, if an attacker enters the zone, they don’t have any option but to find a way into your network.

This is not easy in a zero-trust environment. DMZs provide network segmentation to protect the internal corporate network. The zone isolates critical resources to ensure that an attack does not cause any loss or damage to the organization.

How Does a Network DMZ Work?

Organizations that host a corporate public website must make their server accessible through the internet. This puts their internal network at risk from cyber attackers. The business can prevent this by hosting the website or servers on a firewall, which can affect performance. Therefore, public servers are hosted on a network that is isolated.

A demilitarized zone (DMZ) network facilitates a buffer between the private network of the business and the internet. It is isolated using a firewall that filters the traffic and directs it to either the LAN or the DMZ. The DMZ server is safeguarded by another gateway filtering traffic that comes from external networks.

The zone is ideally located between two firewalls, and the firewall setup ensures that every incoming packet is checked before entering the servers hosted on the DMZ. This implies that even if an attacker gets past the first firewall, it must access the robust services in the DMZ before causing any harm to the business.

If an intruder penetrates the external firewall and enters the DMZ, it has to get past an internal firewall before accessing any sensitive business data. A sophisticated attacker might be able to breach a DMZ, but the system consists of alerts that provide warning signs about a breach in progress.

Benefits of Using a DMZ

The primary advantage of using a DMZ is to facilitate an extra layer of security for the company’s internal network. It enables users to access certain services while creating a buffer to protect the private network of the organization and sensitive data and servers.

A Demilitarized Zone also offers several additional security benefits:

Enables Access Control

A business allows people to use its services through the web. The DMZ implements network segmentation to ensure unauthorized users cannot reach the private network.

It can also include a proxy server to centralize the flow of internal traffic and simplify traffic monitoring and recording.

Prevents Network Reconnaissance

A DMZ, by creating a buffer between the private network and the internet, blocks attackers from carrying out reconnaissance work to look for potential targets.

Servers placed in the demilitarized zone have public exposure but stay protected with an extra firewall that blocks attackers from intruding on the private network.

Even when the system gets compromised, the firewall keeps the private network separated from the DMZ to keep it protected and avoid any external reconnaissance.

Blocks IP Spoofing

Cyber attackers generally try and find ways to gain access to systems by spoofing the IP address of a device authorized to sign into a network.

A DMZ can identify such spoofing attempts as the other service verifies how legitimate the IP address is.

It also offers network segmentation to build a space for traffic to keep it organized and give access to public services away from the private network.

DMZ Design and Architecture

There are several ways to design a demilitarized zone network ranging from single-firewall to dual and multiple firewalls. Most DMZ architectures today use dual firewalls as they can be easily expanded to accommodate more complex systems.

  • Single Firewall: A demilitarized zone network with this type of design needs three or more interfaces – an external network that connects the internet to the firewall, the internal network, and the one that connects to the DMZ. Organizations can set up rules to control and monitor this zone’s traffic and restrict access to the LAN.
  • Dual Firewall: A more secure option is to put two firewalls and a perimeter network between them. The first gateway allows external traffic to the zone, while the second allows only the traffic going from DMZ into the internal network. An intruder must compromise both the firewalls to gain access to the business LAN.


A network demilitarized zone, or DMZ, is an essential component of network security. These subnetworks generate a tiered security structure, which reduces the likelihood of an attack as well as its impact in the event that it does take place.

They are utilized in the process of isolating a corporation’s applications that face the outside world from the internal network of the organization. It is best practice to place a system or application in a DMZ if it is exposed to the public internet.

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