What is the Domain Name System (DNS)?
The Domain Name System (DNS) is like a phonebook for the Internet. The DNS catalogs a web page’s IP address—a multi digit identification code—which is its primary name tag on the home server. IP addresses can be long and cumbersome to memorize. Though it's possible to visit some websites by typing in their IP address, it's much more user-friendly to type in (and remember) a URL. That’s where domain names, and the DNS come into play.
When individuals navigate the web using domain names such as venafi.com, their web browsers communicate via Internet Protocol (IP) addresses. The Domain Name System (DNS) serves as a translator, converting domain names into IP addresses that browsers use to retrieve online resources. Essentially, DNS is the mechanism that assigns user-friendly names to websites, which are easier for people to remember than the numerical IP addresses used by the network.
DNS is an important element in the process of accessing internet content—no web content can be loaded without first undergoing DNS resolution. This role makes DNS filtering or DNS traffic blocking a powerful tool for controlling the type of content users are able to access on the internet.
What is DNS Traffic?
DNS traffic refers to the flow of data between devices and DNS servers that helps to translate human-friendly domain names into IP addresses that computers use to identify each other on the network. When you type a website URL into your browser, a DNS query is initiated. This query is a part of DNS traffic and is essential for your device to understand which server on the internet it needs to connect to in order to access the desired website. Essentially, every time you visit a new website, send an email, or connect to a new online service, DNS traffic is generated. This process is fundamental to how the internet operates, acting as the backbone for routing the multitude of daily requests to the correct website servers across the global web.
SSL/TLS Certificates and Their Prevalence on the Dark Web
What is DNS Traffic Blocking and how does it work?
DNS traffic blocking, often referred to as DNS filtering or DNS blocking, is a network management process that prevents access to specific websites or internet services based on their domain names. This is achieved by configuring DNS servers to refuse resolving certain domain names into IP addresses, effectively making these websites unreachable. Organizations use DNS traffic blocking to enforce web access policies, enhancing security by blocking access to malicious sites, or to comply with regulatory requirements. Additionally, DNS blocking is a common method for implementing parental controls, as it can restrict access to inappropriate content. It is also used in certain geopolitical contexts to censor the internet and block access to information. DNS traffic blocking serves as a straightforward but powerful tool to control and secure internet usage on a network.
At the DNS level, various security strategies can be adopted to enhance protection. For instance, DNS traffic blocking can safeguard users in your organization from accessing harmful websites through phishing emails. When a user clicks on a link within such an email, their computer sends a DNS query to your organization's DNS resolver which employs DNS filtering techniques. Should the targeted site be listed on your organization's blocklist, the DNS resolver will deny the request, effectively stopping the malicious website from loading and thereby preventing potential security breaches.
A DNS traffic block functions by effectively erasing the IP address from your server's “phonebook”, rendering it incapable of finding specific web pages. To block entire categories of websites, such as piracy sites, DNS blocking services can configure your server to disregard extensive ranges of IP addresses based on predefined criteria. This disruption in communication between the IP server and the user's device makes DNS traffic blocking a viable method to restrict access to harmful or undesirable websites. This approach requires minimal system resources and does not necessitate any physical hardware.
Block malware and phishing attacks
Many DNS traffic blockers, or filters, streamline their operations by organizing websites into categories. By default, they block access to certain groups that are notorious for distributing malware, recognized as phishing sites, or considered risky due to hosting exploitable security flaws. This categorization helps in effectively maintaining network safety by preemptively denying access to potentially dangerous online destinations.
Blocking malware
Should your users navigate to a website known for harboring malware, they might be deceived into downloading harmful software or become victims of a drive-by download—where malware is automatically downloaded as soon as the webpage is accessed. DNS traffic blocking can thwart such threats by preventing users from loading these malicious web pages in the first place, effectively blocking the initial contact and subsequent risk.
Blocking phishing attacks
Phishing websites are fake websites that attempt to fool users into giving their account credentials to an attacker. The domains used in phishing attacks could be a spoofed domain or just an official-looking domain that it wouldn’t occur to most users to question. You can prevent users from accessing these websites using DNS traffic blocking.
Why Use DNS Traffic Blocking? Tips for DNS security
Given its role as a critical facilitator of modern web traffic, it’s easy to understand why DNS has become a key tactic in the playbook of cybercriminals. DNS traffic blocking is one of the many tools in your arsenal to prevent inadvertent access to malware and phishing websites.
Here are some of the DNS security best practices that can help you prevent threats originating from this common source.
Use redundant DNS servers
Given the integral role DNS plays in the functioning of network applications like Active Directory, file sharing, and email services, ensuring the high availability of your DNS infrastructure is important. To achieve this, it is essential to have at least two DNS servers—a primary and a secondary—providing redundancy. This setup guarantees that if one server fails or experiences issues, the other can seamlessly take over, thereby enhancing the reliability of your infrastructure and minimizing the potential for service disruptions.
Enable cache locking
Each time DNS processes a query, it retains the information in its cache to expedite future responses to identical queries. This caching is key to decreasing subsequent load times on the server. However, this cache can become a target for cybercriminals who want to infiltrate your systems. Implementing cache locking is a preventive measure that restricts modifications to the cached data, safeguarding it from unauthorized alterations or overwrites until it reaches a predetermined expiration time. Activating cache locking by default and adjusting its duration can effectively shield the data for a specified interval, enhancing your system's security against such exploits.
Use DNS logging
Recording DNS activity through logs is an effective method for detecting anomalies in client interactions, query patterns, updates, and more. These detailed logs are important for uncovering issues such as DNS poisoning or DNS spoofing—tactics where cybercriminals manipulate cached data, misleading the server into directing users from a legitimate website they intended to visit to a malicious one. By analyzing these logs, administrators can identify and address such vulnerabilities, enhancing the security of the DNS environment.
Hide DNS servers and information
It's important to apply the principle of least privilege to DNS servers, much like any other area of IT management. This approach dictates that DNS servers should be accessible solely to designated end users who require them. Your primary server should be kept out of general visibility and limited to system managers and authorized IT personnel only, ensuring that access is tightly controlled and restricted to those specifically entrusted with its management.
Conclusion
DNS traffic blocking is an important tool for maintaining the security of your organization's data and providing security teams with the ability to regulate employee access on company networks. DNS traffic blocking, or filtering, typically forms an integral component of a broader identity and access management strategy. This ensures a controlled and secure environment by overseeing and limiting network access based on established organizational policies.
