Securing Your Opnsense Network with Unbound DNS over HTTPS (DoH)

DNS over HTTPS (DoH) enhances your network's privacy and security by encrypting DNS queries. This guide details how to configure Unbound, a powerful and flexible DNS resolver, with DoH support on your Opnsense firewall. This offers significant advantages over traditional DNS, protecting your browsing activity from eavesdropping and manipulation.

Why Use DoH with Unbound on Opnsense?

Using DoH with Unbound on Opnsense provides several key benefits:

• Enhanced Privacy: DoH encrypts your DNS queries, preventing your ISP and other potential observers from seeing which websites you're visiting.
• Improved Security: Encryption protects against DNS spoofing and other attacks that could redirect you to malicious websites.
• Centralized Management: Managing DNS resolution from your Opnsense firewall provides a single point of control and simplifies configuration for all devices on your network.
• Flexibility: Unbound is highly configurable, allowing you to tailor DNS resolution to your specific needs, including specifying upstream DoH resolvers and implementing advanced features.
• Performance: Unbound is a fast and efficient DNS resolver, ensuring quick and reliable name resolution.

Configuring Unbound with DoH on Opnsense

The following steps outline the configuration process. Remember to replace placeholder values with your own.

1. Access Opnsense WebGUI

Log in to your Opnsense web interface using your administrator credentials.

2. Navigate to Unbound

Go to Services > DNS Resolver > General settings.

3. Enable Unbound

Ensure that the "Enable" checkbox is ticked.

4. Configure Upstream DoH Servers

Under the "Advanced settings" tab, locate the "Forwarders" section. Instead of using traditional forwarders, you'll configure DoH servers. You'll need to add DoH servers as custom forwarders using the following format:

https://dns.google/dns-query

You can add multiple DoH servers for redundancy. Popular options include:

• https://dns.google/dns-query (Google Public DNS)
• https://cloudflare-dns.com/dns-query (Cloudflare DNS)
• https://doh.opendns.com/dns-query (OpenDNS)
• https://doh.quad9.net/dns-query (Quad9)

Remember to replace the example with your chosen server addresses.

5. Configure DNSSEC

Enabling DNSSEC adds an extra layer of security by verifying the authenticity of DNS responses. Consider enabling this option under the "Advanced settings" tab.

6. Apply Changes

Save the configuration and allow Opnsense to apply the changes. This may take a few moments.

7. Test Your Configuration

After applying the changes, test your DNS resolution using a tool like dig or nslookup. Check if it is successfully resolving names using your specified DoH servers.

Troubleshooting

If you encounter issues, double-check the following:

• Correct DoH Server URLs: Ensure the DoH server URLs are entered accurately.
• Network Connectivity: Verify that your Opnsense firewall has internet access.
• Firewall Rules: Ensure that your firewall rules don't block the necessary ports for DoH communication (typically port 443).
• Opnsense Restart: In some cases, a reboot of your Opnsense box might be necessary for the changes to take full effect.

Conclusion

By configuring Unbound with DoH on your Opnsense firewall, you significantly enhance the privacy and security of your network. This comprehensive guide provides step-by-step instructions to secure your DNS traffic, offering a robust and efficient solution for managing DNS resolution within your home or business network. Remember to monitor your DNS logs and periodically review your chosen DoH providers' security and privacy practices.