In the current age of technology, where preserving one’s online privacy and security is of paramount importance, it is essential to ensure the confidentiality of your online activities. While many aspects of online privacy are widely discussed, DNS privacy is an often-overlooked area that deserves attention. The Domain Name System (DNS) acts as the internet’s phone book, translating human-readable domain names into machine-readable IP addresses. However, this process can expose your online activity and compromise your privacy if not properly secured.
Before delving into DNS privacy concerns, let’s first understand how DNS works. DNS can be thought of as the internet’s phonebook. Just like a phonebook helps us find the contact details of a person, DNS helps computers find the location of websites. When we type a website address, such as “google.com,” our computer needs to convert it into an IP address to establish a connection. This process is known as resolving the DNS query.
The DNS system is structured hierarchically, similar to a tree. To resolve a DNS query, our DNS resolver starts at the top of this tree and works its way down, gathering information about each segment of the URL. This recursive process involves checking each level of the domain, from the top-level domain (TLD) to subdomains, until it reaches the bottom.
A recursive resolver first queries an authoritative root server to confirm the top-level domain and then queries the authoritative server for the specific domain. This process involves multiple nodes that can log and access the original DNS query, potentially compromising your privacy.
The Privacy Implications of DNS
While DNS is crucial for internet connectivity, it also poses privacy risks. When we leak our DNS information, it is as if we are publicly announcing our online activities. Both authoritative servers and our DNS resolvers have access to this information, making it vulnerable to exploitation.
- Leaking Personal Information: By examining DNS requests, authoritative servers can create detailed profiles of users’ online behavior, leading to privacy violations. Advertisers, intelligence agencies, and other entities may find this information valuable for various purposes.
- ISP Data Collection: Internet Service Providers (ISPs) often run DNS resolvers, and they are notorious for collecting and selling user data. The terms and conditions of ISP contracts may hide privacy-compromising clauses, allowing them to harvest and exploit users’ browsing data.
- DNS Snooping: DNS traffic is typically transmitted in clear text, making it susceptible to snooping. Certain governments and threat actors use DNS snooping to collect data, especially in regions lacking strong privacy regulations.
Mitigating the Threat
Given the privacy implications of DNS, it is crucial to take steps to safeguard our DNS queries. By configuring our DNS resolver and choosing privacy-focused DNS providers, we can enhance our online privacy significantly.
To enhance end-user privacy protection, two key changes can be made to the DNS resolution process:
- Providing confidentiality through encryption.
- Minimizing the information leaked to DNS authoritative name servers.
Encryption Protocols for DNS Privacy
Encrypting DNS transactions is a crucial step in safeguarding your privacy. Several protocols have been developed to encrypt and authenticate DNS transactions:
- DNSCrypt: Although not standardized by the Internet Engineering Task Force (IETF), DNSCrypt encrypts and authenticates DNS transactions between stub resolvers and recursive resolvers.
- DoT (DNS over TLS): Defined in RFC 7858, DoT uses TLS to provide privacy through encryption.
- DoD (DNS over Datagram Transport Layer Security): An experimental protocol defined in RFC 8094, DoD relies on the DTLS protocol to protect UDP traffic, similar to how TLS protects TCP traffic.
- DoH (DNS over HTTPS): Defined in RFC 8484, DoH allows DNS queries and responses to be sent over the HTTP Secure protocol, leveraging the encryption provided by TLS.
These protocols encrypt DNS transactions between stub resolvers and recursive resolvers, and in some cases, between recursive resolvers and authoritative name servers. Implementation and deployment of these techniques require support in both the resolver and appropriate configuration.
Limiting Data Leakage – QNAME Minimization
In addition to encryption, minimizing the information leaked to authoritative name servers is essential for DNS privacy. Traditionally, the DNS resolution process involves resending the original query to each authoritative name server contacted. However, a technique called QNAME minimization mitigates this information leakage.
QNAME minimization modifies the DNS resolution procedure at the recursive resolver, only resending the original query when strictly necessary. Instead of resending the query to each authoritative name server, the resolver queries for the authority of each involved domain zone, starting from the root zone. This significantly reduces the exposure of the original query to authoritative name servers. Many popular resolvers already support QNAME minimization as the default setting.
Recommended DNS Privacy Providers
To ensure DNS privacy, it is crucial to choose a DNS resolver that supports encryption protocols and prioritizes privacy protection. Here are some recommended providers:
- Quad9: As a non-profit organization, Quad9 provides DNS resolution with support for DoH, DoT, and DNSCrypt. They focus on blocking malicious domains and offer servers in various locations worldwide.
- NextDNS: NextDNS offers both free and commercial services, supporting DoH, DoT, and DoQ. They provide options for adblocking and blocking malicious domains, with individual server configurations based on user preferences.
- AdGuard DNS: AdGuard offers commercial DNS resolution services with support for DoH, DoT, and DNSCrypt. They focus on adblocking and blocking malicious domains, and their servers are hosted by reputable providers. You can also self-host AdGuard DNS.
- Cloudflare DNS: Cloudflare provides DNS resolution services with support for DoH and DoT. They offer customizable configurations and prioritize privacy protection.
Native Operating System DNS Support
Major operating systems have started to include native support for encrypted DNS protocols, making it easier for users to enhance their privacy. For example:
- Android 9 and above support DNS over TLS, which can be configured in the network settings.
- iOS, iPadOS, tvOS, and macOS support both DoT and DoH. Users can configure DNS settings through configuration profiles or the DNS Settings API.
Encrypted DNS Proxies
In situations where native support for encrypted DNS is not available, encrypted DNS proxies can be used to provide a local proxy for unencrypted DNS resolvers. These proxies forward DNS queries to the resolver while adding a layer of encryption. Two popular encrypted DNS proxies are:
- AdGuard Home: AdGuard Home is an open-source DNS sinkhole that provides DNS filtering to block unwanted web content, including advertisements. It features a user-friendly web interface for managing blocked content.
- Pi-hole: Pi-hole is an open-source DNS sinkhole designed to be hosted on platforms like Raspberry Pi. It offers DNS filtering capabilities to block unwanted web content, and it can be accessed through a web interface.
As internet privacy and security concerns continue to grow, DNS privacy plays a vital role in protecting your online activities. By implementing encryption protocols and minimizing data leakage, you can significantly enhance your privacy and ensure that your online browsing remains confidential. Choosing reputable DNS privacy providers and taking advantage of native operating system support for encrypted DNS further strengthens your security posture. By prioritizing DNS privacy, you can navigate the internet with confidence, knowing that your online activities remain private and secure.