Securing Your Network with NetworkManager and DNS over HTTPS (DoH): A Comprehensive Guide

DNS over HTTPS (DoH) is a privacy-enhancing technology that encrypts your DNS queries, preventing your internet service provider (ISP) and potential eavesdroppers from seeing which websites you visit. NetworkManager, a widely used network management service in Linux distributions, provides excellent support for configuring and using DoH. This guide will walk you through the process of setting up DoH with NetworkManager, covering various methods and troubleshooting common issues.

Understanding DNS over HTTPS

Traditional DNS queries are sent in plain text, making them easily intercepted and analyzed. DoH addresses this vulnerability by encrypting these queries using HTTPS, the same protocol used for secure web browsing. This ensures confidentiality and protects your online privacy.

Setting up DoH with NetworkManager

There are several ways to configure DoH with NetworkManager, each offering varying levels of control and flexibility:

1. Using the nmcli Command-Line Tool:

This is a powerful and versatile method suitable for users comfortable with the command line. The following command sets the DoH resolver for a specific connection:

sudo nmcli con mod "Connection Name" ipv4.dns "https://dns.google/dns-query"

Replace "Connection Name" with the actual name of your network connection (e.g., "Wired connection 1", "Wi-Fi connection 1"). You can find the connection name using nmcli con show. Replace "https://dns.google/dns-query" with the DoH URL of your preferred DNS provider. Some popular options include:

• Google Public DNS: https://dns.google/dns-query
• Cloudflare DNS: https://cloudflare-dns.com/dns-query
• Quad9: https://dns.quad9.net/dns-query

To apply the changes, disconnect and reconnect to your network.

2. Modifying the Network Configuration File:

For more granular control, you can directly edit the network configuration file. This file is usually located in /etc/NetworkManager/system-connections/. Find the file corresponding to your connection and add or modify the following lines within the [ipv4] section:

dns=https://dns.google/dns-query

Remember to replace the DoH URL with your preferred provider. Save the file and restart NetworkManager using sudo systemctl restart NetworkManager.

3. Using a Graphical Network Manager (GUI):

Many Linux distributions provide a graphical interface for managing network connections. The specific steps may vary depending on your distribution and the GUI being used. Generally, you'll need to find your connection settings, look for DNS configuration options, and enter the DoH URL there. Consult your distribution's documentation for detailed instructions.

Troubleshooting

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

• Verify the DoH URL: Double-check the URL for typos and ensure it's correct.
• Restart NetworkManager: After making changes, restart NetworkManager using sudo systemctl restart NetworkManager.
• Check Network Connection: Ensure you have a stable internet connection.
• Firewall Rules: Make sure your firewall isn't blocking DoH traffic. You might need to allow outgoing connections on port 443 (HTTPS).
• DNS Resolution Tests: Use tools like nslookup or dig to test DNS resolution and verify that DoH is working correctly.

Choosing a DoH Provider

The choice of DoH provider depends on your priorities. Some providers offer enhanced privacy features, while others prioritize speed and reliability. Research different providers to find one that aligns with your needs.

Conclusion

Implementing DNS over HTTPS with NetworkManager is a straightforward yet effective way to enhance your network security and privacy. By following the steps outlined in this guide, you can easily configure DoH and benefit from the added protection it offers.