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Systemd-resolved and DNS lookup

Cloudflare DNS Setup Guide

DNS Configuration with Custom Scripts

Step-by-step guide to configuring DNS with "dns" and "resolvdinst" scripts

  • 1

    Check Current DNS Configuration

    First, use the script named "dns" to display your currently configured DNS servers.

    The script will output a list of DNS servers configured on your system, similar to this:

  • 2

    Install and Configure systemd-resolved

    Run the script "resolvdinst". This script will:

    • Install systemd-resolved if it is not already installed.
    • Automatically configure the DNS settings to use Cloudflare DNS servers (1.1.1.1 and 1.0.0.1).

    After execution, the script will ensure that the system DNS settings are updated and active.

  • 3

    Verify New DNS Configuration

    Re-run the script "dns" to confirm that the DNS servers have been updated to Cloudflare:

    If the changes are not reflected, check for errors in the "resolvdinst" script output and retry the process.

Modify DNS Configurations

Using the "cdns" script for advanced DNS configuration

  • 1

    Run the "cdns" Script

    The script "cdns" allows you to modify DNS configurations for both /etc/resolv.conf and systemd-resolved.

    When executed, the script will display the following menu options:

    Select an option:
1. Change DNS in systemd-resolved to Cloudflare (1.1.1.1)
2. Change DNS in systemd-resolved to a specific IP address
3. Modify /etc/systemd/resolved.conf
4. Change DNS to Cloudflare (1.1.1.1) in /etc/resolv.conf
5. Modify /etc/resolv.conf
6. Change DNS to a specific IP address
7. Lock DNS
8. Unlock DNS
q. Quit

    Choose the appropriate option based on your requirements to modify DNS settings effectively.

Systemd-resolved with Cloudflare DNS

- without the scripts

  • 1

    Prepare the Environment

    Update the system's package index to ensure all dependencies are available. 
    sudo apt update
  • 2

    Install systemd-resolved

    Install the systemd-resolved package and verify its status. 
    
sudo apt install -y systemd-resolved
if systemctl is-active --quiet systemd-resolved; then
    echo "systemd-resolved is active."
else
    echo "Installation failed."
    exit 1
fi
  • 3

    Configure Cloudflare DNS

    Edit the systemd-resolved configuration file to use Cloudflare's DNS servers:
    • Comment existing DNS lines in /etc/systemd/resolved.conf
    • Add the Cloudflare DNS entries: DNS=1.1.1.1 1.0.0.1
    
sudo sed -i '/^DNS=/s/^/#/' /etc/systemd/resolved.conf
echo "DNS=1.1.1.1 1.0.0.1" | sudo tee -a /etc/systemd/resolved.conf > /dev/null
  • 4

    Restart and Verify

    Restart the systemd-resolved service and check the configuration: 
    
sudo systemctl restart systemd-resolved
resolvectl status | grep 'DNS Servers'
  • 5

    Completion

    Ensure that the system is now using Cloudflare DNS and all changes have been applied successfully.

    Output should confirm DNS Servers: 1.1.1.1 1.0.0.1.