Why You Need a DMZ in Your Network and How it Works

Why You Need a DMZ in Your Network and How it Works. In cyber security, a DMZ provides additional security to defend itself from external attacks in a LAN. The term,’DMZ’ has its origins in the demilitarized zone, which is a geographical buffer zone set between South Korea and North Korea at the end of the Korean War. Just like the Korean boundary DMZ, a network DMZ prevents the movement of traffic into a private business network.

Hence, DMZs are crucial for network security, regardless of the network size. They provide an additional security layer by minimizing internal servers and data access

Shall we start with Why You Need a DMZ in Your Network and How it Works.

What is a DMZ?

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A Demilitarized zone (DMZ) configuration is a logical or physical subnet that isolates an internal LAN from untrusted traffic such as the public internet. Basically, a DMZ sits between the public internet and private network to keep the internal networks secure. In essence, all services provided on the public internet should be initiated in the DMZ network. These include mail, web, Voice over Internet Protocol (VoIP), Domain Name System (DNS), proxy servers, and File Transfer Protocol (FTP).

The servers and resources in the DMZ network are accessible from the internet but are separated with extreme access restrictions to the internal LAN. Because of this, the internal LAN has an extra layer of protection that makes it difficult for a hacker to access the internal servers or data from the internet directly.

On the other hand, it is still possible for cyber criminals and hackers to reach the systems that power services on a DMZ server. Therefore, the security on these servers should be tightened to enable them to withstand constant attacks. The main goal of a DMZ network is to enable organizations to access the public internet while ensuring their LANs or private networks are secure.

What is the Purpose of a DMZ?

The purpose of a DMZ is to protect the hosts with the most vulnerabilities. All in all, DMZ hosts typically involve services that stretch to users that are on the outside of the LAN. The high likelihood of attacks makes it crucial for them to be put into the monitored subnet. In turn, this ensures the rest of the network is secure even if they eventually get compromised.

Additionally, hosts in the DMZ network have access permissions to services inside the internal network. However, this access is strictly controlled as the data being passed through the DMZ is not necessarily secure.

Examples of a DMZ

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If you have a DMZ implemented, you should locate all services involving a external network it. These include:

  • Mail Servers– User databases and emails that contain login credentials and sensitive messages are normally stored on servers that can’t directly access the internet. Here, an email server is created within the DMZ for access and interaction with the email database, whilst protecting it from exposure to potentially harmful traffic.
  • Web Servers– The web servers used to communicate with internal database servers ought to be put inside a DMZ to secure the database. Often, these databases store sensitive information and it’s essential to secure them effectively. Basically, the web then interacts directly with the internal database server or via an application firewall, while still being protected by the DMZ.
  • FTP ServersData transfer servers based on the FTP protocol provide seamless file transfers across the internet and local networks. Because of this, you need to store FTP servers isolated from critical internal systems.

Since the inception of firewalls, DMZ networks have been a crucial component of enterprise network security. With DMZ networks, they help to protect sensitive resources and resources. In addition, DMZ networks are also used for:

Thus, DMZs are vital for network security for both large organizations and individual users. The additional layer of security provides protects your network by limiting access to data and internal servers.

How Does a DMZ Work?

Businesses with public websites have to make their web servers reachable from the internet. This places the entire internal network at high risk. However, this risk is easily averted if the organization hosts its website or its public servers on a firewall. However, this could negatively affect the performance. This is where a DMZ comes in.

Undoubtedly, DMZ network acts as a buffer between an organization’s private network and the internet. Separated by a security gateway, such as a firewall, which filters traffic between the LAN and DMZ. While, the default DMZ server is protected by a different gateway that filters inbound traffic from external networks. It is preferably positioned between two firewalls.

In the same way, DMZ firewall structure ensures that inbound packets are monitored by a firewall or any other security tool before accessing the servers hosted in the DMZ. Even if a malicious attacker manages to bypass the first firewall, the DMZ ensures they can’t compromise the internal network.

If an attacker penetrates the external firewall and compromises a system within the DMZ, the attacker still needs to bypass an internal firewall before they access sensitive business data. In case a sophisticated hacker compromises a secure DMZ, you receive a warning of an ongoing attack from the built in alert systems.

Organizations that have to comply with certain industry regulations such as PCI DSS have to install a proxy server in the DMZ. This makes it easy to filter website content and simplifies the monitoring and logging of user activities.

Architecture and Design of DMZ Networks

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There are several ways to create a network using a DMZ. These are Single Firewall and Dual Firewalls.  Both of these systems can be extended to set up sophisticated DMZ architectures that fulfil network requirements:

1. Single Firewall– This is the most preferred approach to network architecture. Includes a single firewall with a minimum of 3 network interfaces. The DMZ is positioned within this firewall. On balance, it connects to the external network device, that is done from the ISP. A second network device connects the internal network while the third device manages connections inside the DMZ.

2. Dual Firewall– The most secure method of Implementing a DMZ network is using two firewalls. The initial firewall is referred to as the frontend firewall and is designed only to allow traffic that travels towards the DMZ. The second firewall is referred to as the backend firewall and is only responsible for the traffic headed toward the internal network from the DMZ. To further enhance network security, it’s best to use firewalls from multiple providers to reduce the possibility of having similar security vulnerabilities. Not to mention, it is a more efficient but expensive way to design a DMZ for a large network.

With a DMZ in place, the organization can fine tune the different network sections. On balance, you configure an Intrusion Prevention System (IPS) or Intrusion Detection System (IDS) inside a DMZ to block all traffic except Hypertext Transfer Protocol Secure (HTTPS) requests to the Transmission Control Protocol (TCP) port 443.

What are the Benefits of a DMZ?

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The main benefit of using a DMZ is that it offers an additional layer of advanced protection to an internal network by limiting access to servers and sensitive information. This enables safe browsing and protects both the website and the end user.

Additionally DMZ also provides security benefits such as:

Access Control

Businesses offer access to services outside the network to their clients via the public internet. The DMZ network enables this access while guaranteeing network segmentation to make it difficult for unauthorized users to reach the private networks. A proxy server is also included with the DMZ, which simplifies its monitoring and logging and centralizes internal traffic flow.

Preventing Network Reconnaissance

So as to DMZ, it creates a buffer between the internet and a private network. Therefore, it helps prevent attackers from executing reconnaissance that’s done to look for potential targets. Servers located within the DMZ are not exposed to the public. Instead, they have an additional firewall protocol that restricts anyone from analyzing the internal network.

Preventing Network Spoofing

So far, cyber attackers usually gain access to IT systems by impersonating already approved devices and falsifying Internet Protocol addresses. But, a DMZ is capable of tracking down and blocking this kind of attempt as a different service confirms the legitimacy of the Internet Protocol address.

That is to say DMZ allows network segmentation which organizes traffic, and provides access to services without accessing the private internal networks.

What are the Drawbacks of a DMZ?

Some of the drawbacks of a DMZ include:

No Internal Protections

Authorized users such as employees still access the sensitive information being stored for your business. To be sure, your business networks are not fully secure from insider threats.

Does Not Provide Full Protection

With each day cyber attackers crafting complex attack methods of bypassing security systems, DMZ servers can’t guarantee 100% safety. Remember to still monitor your network environment even when your DMZ setup is complete.

Time Consuming

Configuring DMZ networks is time consuming. With the emergence of smart cloud technologies, DMZ is becoming less relevant.

Applications of a DMZ

Here are some real world applications of DMZ:

Cloud Services

Various cloud computing services employ hybrid security. This involves implementing a DMZ between the virtual network and an organization’s on-premises network. This security approach is vital when a business application runs on a virtual network and partially on-premise. DMZ is also useful in auditing outbound traffic or where granular traffic control is compulsory between the on-premise data center and the virtual network.

Home Networks

You can implement a DMZ within home networks where internet enabled devices connect to the internet via a LAN configuration or a broadband router. Some home routers come with a DMZ host feature.

Industrial Control Systems (ICS)

DMZs offer potential solutions to the security risks that ICSs face. Smart industrial machinery are more efficient for production environments. However, this does enlarge the threat surface. Most of the Operational Technology (OT) machinery that is connected to the internet is not built to handle attacks like IT devices are designed to do. A DMZ enables increased network segmentation to make it harder for ransomware and other threats to occupy the space between the IT systems and the more vulnerable OT components.

Thank you for reading Why You Need a DMZ in Your Network and How it Works. let’s conclude this article.

Why You Need a DMZ in Your Network and How it Works Conclusion

Demilitarized zones help maintain high level enterprise security while enabling users to interact with external connections. Currently, most organizations rely on web applications or cloud services for service delivery. As a result, it’s virtually impossible to restrict access to the internal network completely. Therefore, implementing a DMZ between the LAN and the internet enables secure external access. If you have an application or business system facing the public internet, it should be put in a DMZ.

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Avatar for Dennis Muvaa
Dennis Muvaa

Dennis is an expert content writer and SEO strategist in cloud technologies such as AWS, Azure, and GCP. He's also experienced in cybersecurity, big data, and AI.

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