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DNS Firewall

What Is a DNS Firewall?

A Domain Name System (DNS) firewall prevents users from visiting dangerous websites and systems on a network from connecting with known harmful internet sites. To stop data exfiltration, DNS firewalls use DNS response policy zones (RPZs) and actionable threat intelligence that identifies potentially harmful sites that users should not visit.

With automated threat intelligence, DNS firewalls can keep up with the changing cybersecurity threat landscape, help isolate affected devices so they can be cleaned up, and offer insights into potentially risky websites.

How Do DNS Firewalls Work?

DNS firewall rules are specifically created to secure an organization's internal systems. They filter traffic that flows through a DNS firewall port. Typically, DNS entries are redirected to the firewall vendor's nameservers. All incoming traffic gets examined at this point and compared against a set of guidelines and policies. If any of these policies or guidelines are violated, the web request is banned.

How Does a DNS Firewall Help Resolve Business Security Challenges?

A DNS firewall protects your DNS from attacks like distributed denial-of-service (DDoS) and cache poisoning, which sends visitors to malicious websites. When a user submits a query, the DNS server examines the query's hostname and IP address and compares them to a list of known risks. If these are deemed secure, the DNS will return the address. But if the DNS server detects danger, it will direct the user to a safe landing page.

The goal of DNS security is to stop issues before they impact computers, users, or your network. As such, DNS firewalls can be extremely helpful, primarily because they keep employees, visitors, and other users from connecting with harmful sites.  

Here are some ways DNS firewalls can help resolve business security issues:

Monitor Internet Activity Across Multiple Locations

Organizations with numerous offices require a centralized location to monitor threats and the websites employees visit. DNS firewalls give you this option. For example, if users in a certain location start using a site that presents a threat, you can use a DNS firewall to block access to it. Also, as you discover problematic sites, you can simultaneously prevent all users, regardless of where they are physically located, from accessing these sites.

Provide Detailed Threat-blocking Capabilities

Every DNS request is directed to a particular address, and hackers can take advantage of this process to send visitors to malicious sites. With a DNS firewall, you can check the sites employees visit and block potentially dangerous Uniform Resource Locators (URLs).

Safeguard Remote Work Environbments

Today's mobile workforce introduces significant risks. You have no idea where they operate, what dangers they are facing, or what sort of browsing habits they have. A virtual private network (VPN) protects communication between two points, and a DNS firewall manages access to certain websites, helping to limit the risks remote employees have to contend with.

Protect Employees While They Are at Home

You can stop numerous threats from ever reaching your organization by using a DNS firewall on your employees’ browsers. This is especially helpful if your organization has a bring-your-own-device (BYOD) policy. A DNS firewall can prevent various threats—including malware, ransomware, and data exfiltration attacks—from getting to your office network by first attacking an employee’s computer at home.

For example, suppose an employee has a DNS firewall on their laptop, and they attempt to visit a site that is known to distribute malware. The DNS firewall can block access to the site. Without it, the employee could have gone to the site, brought their laptop to work, connected to your network, and spread the malware throughout the organization's system.

Get Security Without Sacrificing Privacy

Your internet service provider (ISP) knows every website you visit because DNS converts hostnames to IP addresses. But with a DNS firewall solution, you can get protection without handing over your entire traffic history to your DNS firewall provider. 

For instance, Google tracks traffic and knows where it is coming from and what is in it. This enables the company to sell targeted marketing data and services to other businesses. But with a business DNS firewall solution, you need not worry about this kind of information collection, primarily because your DNS firewall vendor will likely not collect data regarding traffic.

DNS Firewall vs. Next-generation Firewall—How To Choose the Best Firewall for Your Enterprise?

A next-generation firewall (NGFW) provides deep packet filtering that goes beyond simple port/protocol inspection and blocking. In this way, an NGFW gives you application-level inspection and intrusion prevention, making it very different from a DNS firewall. 

Here are some specific ways the two solutions are different:

An NGFW Is a Defensive Tool

An NGFW will respond if your network is attacked because NGFWs react after an assault has already been initiated. Therefore, an NGFW functions as a defensive mechanism—one that is reactive rather than proactive. 

The speed and volume of new attack techniques make it possible for malware to sit dormant and go undiscovered for weeks or even months. Therefore, it can be dangerous to only depend on a firewall to protect your network, especially if it does not have the ability to detect these kinds of attacks, which can live in your system for extended periods of time.

DNS Firewalls Take Preventative Measures to Block Malicious Traffic

A DNS firewall can block hostile websites by preventing users from accessing them in the first place. In this capacity, a DNS firewall is significantly quicker, more responsive, and more successful in safeguarding users from malicious websites, whether employees work inside or outside your network perimeter.

A Next-Generation Firewall Provides Advanced Protection

However, despite the ability of a DNS firewall to prevent access to dangerous sites, there are some things it cannot do that an NGFW can. For example, an NGFW can inspect the contents of data packets to detect threats inside them. A DNS firewall cannot do that.

A DNS firewall is like a security officer in a post office with a list of mail bombers and where they live. The officer checks the addresses of every package that comes through to see if it is from someone who tends to send mail bombs.

But what happens if a new mail bomber living at an address the security officer has not heard of comes on the scene? The officer may let the dangerous package pass through.

But an NGFW with the right firewall configuration is like a security officer who checks each package’s address and opens it to see what is inside. Which officer is more likely to stop a mail bomb? The one that opens the package, of course. Similarly, an NGFW can protect your organization from certain threats a DNS firewall may miss. This is one of the most significant firewall benefits of an NGFW.

Types of Threats Blocked by DNS Firewalls

That being said, a DNS firewall does block a number of internet-based threats, including:

  1. Data theft
  2. Phishing sites
  3. Adware
  4. Ransomware downloads
  5. Spyware
  6. Hijacked IP addresses
  7. Botnet nodes and hosts

It blocks these threats, not by identifying the threat itself but by identifying the website that may carry the threat. The DNS firewall then prevents traffic from that website from entering your network.

How Fortinet Can Help?

With the Fortinet FortiGate Next-Generation Firewall, your organization can block malicious websites using FortiGate DNS filtering and benefit from deep packet inspection. Unlike some firewalls, FortiGate provides extremely high throughput, preventing latency as it protects your environment in real time.


Do I need a DNS firewall?

Because a DNS firewall can shield employees from accessing malicious websites, it is a very useful tool. However, many companies do not necessarily “need” one, particularly if they have a next-generation firewall (NGFW). This is because an NGFW can also come equipped with DNS filtering, which prevents employees from accessing dangerous sites. Also, as is the case with FortiGate, if the NGFW gets threat intelligence from a global defense system, it can use that data to protect users from numerous bad sites.

How do you make DNW work with a firewall?

Your Domain Name System (DNS) and firewall work in tandem. Your DNS connects the website addresses users type into their browsers with the sites they are supposed to go to. Your firewall prevents those users from getting to dangerous sites.