Overriding DNS in Debian 12

Oct 13, 2025 by wbrum.org 123 views

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Introduction

Debian 12, also known as Bookworm, is a popular Linux distribution that offers a wide range of features and tools for system administrators. One of the common tasks that system administrators perform is configuring the DNS settings on their network. In this article, we will discuss how to override the DNS settings in Debian 12 to bypass a DNS service like Pi-hole.

Understanding DNS

DNS (Domain Name System) is a critical component of the internet infrastructure that translates human-readable domain names into IP addresses that computers can understand. When you enter a URL in your web browser, your computer sends a request to a DNS server to resolve the domain name into an IP address. The DNS server then returns the IP address, which your computer uses to connect to the website.

Pi-hole and DNS Bypass

Pi-hole is a popular open-source DNS service that blocks ads and trackers on your network. However, in some cases, you may need to bypass Pi-hole and use a different DNS service, such as 1.1.1.1. This can be useful if you need to access a website or service that is blocked by Pi-hole.

Overriding DNS in Debian 12

To override the DNS settings in Debian 12, you can use the resolvconf command. However, this method is not recommended as it can cause conflicts with other DNS services on your network. A better approach is to use the systemd-resolved service, which is the default DNS resolver in Debian 12.

Method 1: Using `systemd-resolved`

To override the DNS settings using systemd-resolved, you can create a file in the /etc/systemd/resolved.conf.d/ directory. This file will contain the DNS settings that you want to use.

sudo nano /etc/systemd/resolved.conf.d/override.conf

In this file, add the following lines:

[Resolve]
DNS=1.1.1.1

Save and close the file. Then, reload the systemd-resolved service to apply the changes:

sudo systemctl reload systemd-resolved

Method 2: Using `/etc/resolv.conf`

Another way to override the DNS settings is to edit the /etc/resolv.conf file directly. However, this method is not recommended as it can cause conflicts with other DNS services on your network.

sudo nano /etc/resolv.conf

In this file, add the following lines:

nameserver 1.1.1.1

Save and close the file. Then, reload the systemd-resolved service to apply the changes:

sudo systemctl reload systemd-resolved

Method 3: Using a Network Manager

If you are using a network manager like NetworkManager, you can override the DNS settings by editing the network configuration file.

sudo nano /etc/NetworkManager/system-connections/your-connection-name

In this file, add the following lines:

[ipv4]
method=manual
dns=1.1.1.1

Save and close the file. Then, reload the NetworkManager service to apply the changes:

sudo systemctl reload NetworkManager

Conclusion

In this article, we discussed how to override the DNS settings in Debian 12 to bypass a DNS service like Pi-hole. We covered three methods: using systemd-resolved, editing the /etc/resolv.conf file, and using a network manager. Remember to always use the recommended method and to reload the relevant service to apply the changes.

Additional Tips

Make sure to backup your DNS settings before making any changes.
If you are using a DNS service like Pi-hole, make sure to configure it to work with the new DNS settings.
If you are experiencing issues with your DNS settings, try restarting the systemd-resolved service or the NetworkManager service.

Troubleshooting

If you are experiencing issues with your DNS settings, try the following troubleshooting steps:

Check the DNS settings in the /etc/resolv.conf file or the /etc/systemd/resolved.conf.d/override.conf file.
Check the DNS settings in the network configuration file.
Try restarting the systemd-resolved service or the NetworkManager service.
Try flushing the DNS cache using the sudo systemd-resolve --flush-caches command.

FAQs

Q: How do I configure Pi-hole to work with the new DNS settings? A: You can configure Pi-hole to work with the new DNS settings by editing the Pi-hole configuration file and setting the DNS server to the new IP address.
Q: How do I reset the DNS settings to their default values? A: You can reset the DNS settings to their default values by deleting the /etc/systemd/resolved.conf.d/override.conf file or the /etc/resolv.conf file and reloading the systemd-resolved service.
Q: How do I troubleshoot DNS issues? A: You can troubleshoot DNS issues by checking the DNS settings in the /etc/resolv.conf file or the /etc/systemd/resolved.conf.d/override.conf file, checking the DNS settings in the network configuration file, and trying restarting the systemd-resolved service or the NetworkManager service.

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Q: What is the purpose of overriding DNS in Debian 12?

A: The purpose of overriding DNS in Debian 12 is to bypass a DNS service like Pi-hole and use a different DNS service, such as 1.1.1.1. This can be useful if you need to access a website or service that is blocked by Pi-hole.

Q: How do I configure Pi-hole to work with the new DNS settings?

A: You can configure Pi-hole to work with the new DNS settings by editing the Pi-hole configuration file and setting the DNS server to the new IP address. You can do this by running the following command:

sudo nano /etc/pihole/setupVars.conf

In this file, add the following lines:

DNS1=1.1.1.1

Save and close the file. Then, restart the Pi-hole service to apply the changes:

sudo service pihole-FTL restart

Q: How do I reset the DNS settings to their default values?

A: You can reset the DNS settings to their default values by deleting the /etc/systemd/resolved.conf.d/override.conf file or the /etc/resolv.conf file and reloading the systemd-resolved service. You can do this by running the following commands:

sudo rm /etc/systemd/resolved.conf.d/override.conf
sudo rm /etc/resolv.conf
sudo systemctl reload systemd-resolved

Q: How do I troubleshoot DNS issues?

A: You can troubleshoot DNS issues by checking the DNS settings in the /etc/resolv.conf file or the /etc/systemd/resolved.conf.d/override.conf file, checking the DNS settings in the network configuration file, and trying restarting the systemd-resolved service or the NetworkManager service. You can also try flushing the DNS cache using the sudo systemd-resolve --flush-caches command.

Q: What are the benefits of using `systemd-resolved`?

A: The benefits of using systemd-resolved include:

Automatic DNS configuration
Support for multiple DNS servers
Support for DNSSEC validation
Support for DNS over TLS (DoT)
Support for DNS over HTTPS (DoH)

Q: How do I configure `systemd-resolved` to use a specific DNS server?

A: You can configure systemd-resolved to use a specific DNS server by creating a file in the /etc/systemd/resolved.conf.d/ directory. This file will contain the DNS settings that you want to use. For example, to use the 1.1.1.1 DNS server, you can create a file called override.conf with the following contents:

[Resolve]
DNS=1.1.1.1

Save and close the file. Then, reload the systemd-resolved service to apply the changes:

sudo systemctl reload systemd-resolved

Q: How do I configure `systemd-resolved` to use multiple DNS servers?

A: You can configure systemd-resolved to use multiple DNS servers by creating a file in the /etc/systemd/resolved.conf.d/ directory. This file will contain the DNS settings that you want to use. For example, to use the 1.1.1.1 and 8.8.8.8 DNS servers, you can create a file called override.conf with the following contents:

[Resolve]
DNS=1.1.1.1 8.8.8.8

Save and close the file. Then, reload the systemd-resolved service to apply the changes:

sudo systemctl reload systemd-resolved

Q: How do I configure `systemd-resolved` to use DNSSEC validation?

A: You can configure systemd-resolved to use DNSSEC validation by creating a file in the /etc/systemd/resolved.conf.d/ directory. This file will contain the DNS settings that you want to use. For example, to enable DNSSEC validation, you can create a file called override.conf with the following contents:

[Resolve]
DNSSEC=yes

Save and close the file. Then, reload the systemd-resolved service to apply the changes:

sudo systemctl reload systemd-resolved

Q: How do I configure `systemd-resolved` to use DNS over TLS (DoT)?

A: You can configure systemd-resolved to use DNS over TLS (DoT) by creating a file in the /etc/systemd/resolved.conf.d/ directory. This file will contain the DNS settings that you want to use. For example, to use the 1.1.1.1 DNS server over DoT, you can create a file called override.conf with the following contents:

[Resolve]
DNS=1.1.1.1
DNSOverTLS=yes

Save and close the file. Then, reload the systemd-resolved service to apply the changes:

sudo systemctl reload systemd-resolved

Q: How do I configure `systemd-resolved` to use DNS over HTTPS (DoH)?

A: You can configure systemd-resolved to use DNS over HTTPS (DoH) by creating a file in the /etc/systemd/resolved.conf.d/ directory. This file will contain the DNS settings that you want to use. For example, to use the 1.1.1.1 DNS server over DoH, you can create a file called override.conf with the following contents:

[Resolve]
DNS=1.1.1.1
DNSOverHTTPS=yes

Save and close the file. Then, reload the systemd-resolved service to apply the changes:

sudo systemctl reload systemd-resolved

Q: How do I troubleshoot issues with `systemd-resolved`?

A: You can troubleshoot issues with systemd-resolved by checking the system logs for errors, checking the DNS settings in the /etc/resolv.conf file or the /etc/systemd/resolved.conf.d/override.conf file, and trying restarting the systemd-resolved service. You can also try flushing the DNS cache using the sudo systemd-resolve --flush-caches command.