Dnsmasq is a lightweight DNS forwarder and DHCP server that is commonly used on various Linux distributions, including Ubuntu. However, you might want to disable Dnsmasq from listening on port 53 for various reasons, such as avoiding conflicts with other DNS services or improving security.
Original Problem Scenario
You may have encountered a situation where Dnsmasq is actively listening on port 53, causing unwanted behavior or conflicts with other services. The original question might have been framed like this: "How do I stop Dnsmasq from listening on port 53 in Ubuntu 20.04?"
Understanding Dnsmasq and Port 53
Port 53 is the default port for DNS services. When Dnsmasq is running on this port, it can interfere with other DNS resolvers or services that you want to utilize on your system. Disabling Dnsmasq on this port may be essential, especially when using alternative DNS servers or software like systemd-resolved.
Steps to Disable Dnsmasq on Port 53
Here’s a step-by-step guide to stop Dnsmasq from listening on port 53 in Ubuntu 20.04:
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Check Dnsmasq Status First, you should check whether Dnsmasq is running on your system. Open the terminal and run the following command:
sudo systemctl status dnsmasq -
Stop Dnsmasq If Dnsmasq is currently running, you can stop it by executing:
sudo systemctl stop dnsmasq -
Disable Dnsmasq from Starting Automatically To prevent Dnsmasq from starting automatically at boot, use the following command:
sudo systemctl disable dnsmasq -
Remove Dnsmasq (Optional) If you don’t need Dnsmasq at all, you can remove it completely:
sudo apt remove dnsmasq -
Verify Port 53 is No Longer in Use After stopping Dnsmasq, verify that port 53 is no longer being listened to by any process. Use this command:
sudo netstat -tuln | grep :53
Additional Considerations
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Firewall Configuration: If you are using UFW (Uncomplicated Firewall), ensure that it is configured correctly to allow or deny DNS traffic as needed.
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Alternative DNS Services: If you plan to use an alternative DNS service, make sure to configure it properly to utilize port 53 without conflicts.
Practical Example
Imagine you have installed Unbound, a caching DNS resolver, and you find that it is not functioning correctly. The reason might be that Dnsmasq is still running on port 53, leading to conflicts. Following the above steps to disable Dnsmasq allows Unbound to operate smoothly.
Conclusion
Disabling Dnsmasq from listening on port 53 on Ubuntu 20.04 is straightforward and can prevent various conflicts with other DNS services. By following the steps outlined above, you can ensure that your system operates efficiently without unnecessary interruptions.
Useful Resources
By utilizing these steps and considerations, you should be able to manage Dnsmasq effectively on your Ubuntu system and improve your DNS management processes.
