How to Configure Squid Proxy Server for IPv6

How to Configure Squid Proxy Server for IPv6

As the internet continues to grow, the pool of available IPv4 addresses is rapidly depleting. This has led to the development and gradual adoption of IPv6, a newer version of the Internet Protocol that provides a vastly larger number of addresses. If you’re running a Squid proxy server, it’s important to ensure that it’s configured to handle IPv6 traffic.

This tutorial will guide you through the process of configuring your Squid server for IPv6 on CentOS.

The benefits of configuring your Squid proxy server for IPv6 include future-proofing your network infrastructure, improving compatibility with modern devices and networks, and taking advantage of the improved performance and security features offered by IPv6.

Before we start, make sure you have Squid installed on your server. If you haven’t installed it yet, you can follow the instructions in our previous tutorial on how to install Squid.

Step 1: Checking IPv6 Support

The first step is to check if your server’s operating system and Squid version support IPv6. You can do this by running the following command:

squid -v

Look for the ‘–enable-ipv6’ flag in the output. If it’s present, it means that your Squid version supports IPv6.

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Step 2: Configuring Squid for IPv6

Open the Squid configuration file with your preferred text editor. In this tutorial, we’ll use nano:

nano /etc/squid/squid.conf

Find the following lines:

http_port 3128

Replace them with:

http_port [::]:3128

The ‘[::]’ syntax is used to specify an IPv6 address. In this case, it means “any IPv6 address”.

Step 3: Allowing IPv6 Connections

Next, you need to configure Squid to allow incoming IPv6 connections. Add the following lines to the Squid configuration file:

acl localnet src ::1/128
http_access allow localnet

The ‘acl localnet src ::1/128’ line defines an access control list (ACL) that matches any traffic coming from the IPv6 localhost address (::1). The ‘http_access allow localnet’ line allows HTTP access from any source defined in the ‘localnet’ ACL.

Step 4: Restarting Squid

After making these changes, save and close the Squid configuration file. Then, restart Squid to apply the changes:

systemctl restart squid

Step 5: Testing the Configuration

Finally, test your configuration to make sure that Squid is correctly handling IPv6 traffic. You can do this by running the following command:

curl -x [::1]:3128

If the command returns the HTML content of the Google homepage, it means that your Squid proxy server is correctly configured for IPv6.

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Commands Mentioned:

  • squid -v – Checks the version and configuration options of Squid.
  • nano /etc/squid/squid.conf – Opens the Squid configuration file in the nano text editor.
  • systemctl restart squid – Restarts the Squid service, applying any changes made to the configuration file.
  • curl -x [::1]:3128 – Tests the Squid proxy server’s handling of IPv6 traffic.


Congratulations! You’ve successfully configured your Squid proxy server for IPv6. By doing so, you’ve ensured that your proxy server is ready to handle the modern internet’s demands and can interact with IPv6 networks and devices. This is an important step in future-proofing your network infrastructure and staying compatible with the latest internet technologies.

Remember, as with any server configuration changes, it’s important to monitor your server after making these changes to ensure that everything is running smoothly.

Hope you found this tutorial helpful.

If you have any questions or run into any issues, feel free to leave a comment below.


  1. Why do I need to configure Squid for IPv6?

    IPv6 is the latest version of the Internet Protocol. As IPv4 addresses run out, more devices and networks are using IPv6. Configuring Squid for IPv6 ensures your proxy server can interact with these networks and devices.

  2. What does the ‘::’ in ‘[::]:3128’ mean?

    In IPv6, ‘::’ is a shorthand that represents multiple groups of zeros. In the context of the ‘http_port’ directive, ‘[::]’ means ‘any IPv6 address’.

  3. How can I check if my server supports IPv6?

    You can check if your server supports IPv6 by running the ‘ip -6 addr’ command. If the command returns an IPv6 address, your server supports IPv6.

  4. What should I do if the ‘curl’ command doesn’t return the expected output?

    If the ‘curl’ command doesn’t return the expected output, it means there’s an issue with your Squid configuration or your server’s IPv6 connectivity. Check your Squid configuration file for errors, and ensure that your server can connect to other IPv6 networks.

  5. Can I use both IPv4 and IPv6 with Squid?

    Yes, Squid can handle both IPv4 and IPv6 traffic. You just need to specify separate ‘http_port’ directives for IPv4 and IPv6 in the Squid configuration file.


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