Privacy Protection with DNS over HTTPS (DoH) and DNS over TLS (DoT)

In the digital age, privacy and security have become paramount concerns for internet users. One of the fundamental building blocks of internet communication is the Domain Name System (DNS), which translates human-readable domain names into machine-readable IP addresses. However, traditional DNS queries are sent in plain text, making them susceptible to interception and eavesdropping. Fortunately, technologies like DNS over HTTPS (DoH) and DNS over TLS (DoT) offer enhanced privacy protection. In this article, we’ll explore how DoH and DoT work, their differences, and how they contribute to a more secure online experience.

What is DNS?

Before delving into DoH and DoT, it’s essential to understand what DNS is. DNS acts like a phone book for the internet. When you type a web address into your browser, DNS translates that address into an IP address, allowing your browser to locate and connect to the web server hosting the site.

The Privacy Problem with Traditional DNS

Traditional DNS queries are transmitted in plaintext, which means that anyone monitoring your internet traffic (like your Internet Service Provider (ISP) or a malicious actor) can see which websites you are visiting. This lack of privacy can lead to potential data breaches, targeted advertising, and other privacy violations.

What is DNS over HTTPS (DoH)?

DNS over HTTPS (DoH) is a protocol that encrypts DNS queries using HTTPS, which is the same protocol that secures your web browsing. By sending DNS queries over HTTPS, DoH ensures that your DNS requests are encrypted, making it difficult for third parties to intercept or manipulate DNS traffic.

Key Features of DoH:

• Encryption: Protects DNS queries from eavesdropping.
• Privacy: Hides user browsing habits from ISPs and other entities.
• Integrity: Ensures that DNS responses haven’t been tampered with.

Example of a DoH Request

Here is an example of how a DNS query is sent using DoH:

GET /dns-query?name=example.com&type=A HTTP/1.1
Host: dns.example.com
Accept: application/dns-json

What is DNS over TLS (DoT)?

DNS over TLS (DoT) is another protocol designed to secure DNS queries, but it works differently than DoH. DoT encrypts DNS traffic using the TLS protocol, which is also used to secure many web communications. Unlike DoH, which runs over the standard HTTPS port (443), DoT typically operates over port 853.

Key Features of DoT:

• Encryption: Similar to DoH, DoT encrypts DNS queries to protect user privacy.
• Dedicated Port: Runs over a specific port (853), which can make firewall configurations easier.
• Compatibility: Works with existing DNS infrastructure and is easier to implement for DNS servers.

Example of a DoT Request

Here’s how a DNS query would look when sent using DoT:

Client -> Server: [ClientHello]
Server -> Client: [ServerHello]
Client -> Server: [ClientKeyExchange]
Client -> Server: [Finished]

Comparison: DoH vs. DoT

Benefits of Using DoH and DoT

1. Enhanced Privacy: Both DoH and DoT help protect users’ browsing habits by encrypting DNS queries, preventing third parties from spying on users’ online activities.

2. Security Against DNS Spoofing: By encrypting DNS traffic, these protocols help guard against attacks like DNS spoofing, where an attacker can inject malicious responses.

3. User Control: Many modern browsers and applications allow users to choose between DoH and DoT, giving them control over their security preferences.

4. Improved Performance: DoH can take advantage of HTTP/2 multiplexing, which can lead to faster DNS resolution times.

Implementing DoH and DoT

Configuring DNS over HTTPS

To set up DoH, you can configure your browser or operating system settings to use a DoH-compatible DNS provider. Here’s how to enable DoH in a popular browser like Firefox:

1. Open Firefox and