Securing Your Ubuntu System with DNS over HTTPS (DoH): A Comprehensive Guide

DNS over HTTPS (DoH) is a method of encrypting DNS lookups, enhancing your online privacy and security. This guide provides a comprehensive walkthrough of configuring DoH on your Ubuntu system, covering various methods and troubleshooting common issues.

Why Use DNS over HTTPS?

Traditional DNS queries are sent in plain text, making them vulnerable to eavesdropping and manipulation. DoH encrypts these queries, protecting them from:

• Network eavesdropping: Your ISP or other network observers cannot see which websites you're accessing.
• DNS spoofing and cache poisoning: Malicious actors cannot redirect your traffic to fake websites.
• DNS censorship: Your access to websites is less likely to be blocked or restricted.

Methods for Configuring DoH on Ubuntu

There are several ways to enable DoH on Ubuntu, each with its own advantages and disadvantages:

1. Using NetworkManager (Recommended for most users)

NetworkManager is a powerful tool that simplifies network management. This is the recommended method for most users as it integrates seamlessly with the system.

1. Open NetworkManager settings: You can access this through the system settings or by running nm-connection-editor in the terminal.
2. Edit your connection: Select the connection you want to modify (usually your Wi-Fi or Ethernet connection).
3. Add DoH settings: Navigate to the 'IPv4' or 'IPv6' settings (depending on your connection). Look for an option to specify a DNS server. Enter the DoH address, such as https://dns.google/dns-query for Google Public DNS or https://cloudflare-dns.com/dns-query for Cloudflare DNS.
4. Save changes: Apply the changes and reconnect to your network.

2. Modifying `/etc/resolv.conf` (Advanced users only)

Directly editing `/etc/resolv.conf` is generally not recommended as changes might be overwritten by NetworkManager. However, for advanced users who understand the implications, it's possible to configure DoH this way. **Note:** This method might require additional configuration with systemd-resolved.

This approach usually involves using a DNS client that supports DoH, like `systemd-resolved` with appropriate configuration in `/etc/systemd/resolved.conf`

3. Using a DoH-enabled DNS client (e.g., unbound)

Unbound is a validating, recursive, and caching DNS resolver. It can be configured to use DoH, providing a highly customizable and secure DNS solution. This option requires more technical expertise.

Installation and configuration instructions for unbound can be found in its official documentation. You'll need to configure the DoH provider and then configure your system to use unbound as its primary DNS resolver.

Troubleshooting

If you encounter issues after configuring DoH, try the following:

• Verify your DoH provider address: Ensure you've entered the correct address for your chosen provider.
• Check your network connection: Make sure you have a stable internet connection.
• Restart your network services: Try restarting NetworkManager (sudo systemctl restart NetworkManager) or your chosen DNS client.
• Review your firewall settings: Ensure that your firewall isn't blocking DoH traffic (typically on port 443).

Choosing a DoH Provider

Several reputable providers offer DoH services, including:

• Google Public DNS (https://dns.google/dns-query): Widely used and reliable.
• Cloudflare DNS (https://cloudflare-dns.com/dns-query): Known for its performance and privacy focus.
• Quad9 (https://dns.quad9.net/dns-query): Prioritizes security and blocks malicious domains.

Remember to research each provider's privacy policy to ensure it aligns with your needs.

By following this guide, you can effectively secure your Ubuntu system with DNS over HTTPS, enhancing your online privacy and security.