Introduction

This comprehensive guide will assist you in disabling IPv6 on your server. If your server experiences issues with IPv6 networking, it can lead to problems like backup destination validation timeouts. By disabling IPv6, you can effectively work around these issues.

Important Note: cPanel software support cannot directly modify your server’s network configuration. It’s strongly recommended to have the steps outlined in this article performed by a qualified system administrator.

Top 10 questions that this article can effectively answer:

• How do I disable IPv6 on my cPanel server?
• How to turn off IPv6 in cPanel?
• What is the command to disable IPv6 in cPanel?
• How to fix backup destination validation timeout issues in cPanel?
• Why is my server experiencing problems with IPv6 networking?
• How to make the IPv6 disable setting permanent in cPanel?
• What changes need to be made to the /etc/sysctl.conf file to disable IPv6?
• How do I configure SSH to use only IPv4 after disabling IPv6?
• What is the /etc/ssh/sshd_config file used for in cPanel?
• Why shouldn’t I remove IPv6 kernel modules in cPanel?

Procedure to Disable IPv6

Follow these steps to disable IPv6 on your server:

1. Access your server via SSH: Log in to your server as the root user using Secure Shell (SSH) or Terminal.

2. Disable IPv6 temporarily: Execute the following command:

   echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
   

   This command will disable IPv6, but the change will revert upon reboot.

3. Make the change permanent:

   • Open the /etc/sysctl.conf file using a text editor (e.g., nano or vi). (Example: nano /etc/sysctl.conf)
   • Add / Append the following lines to the file:

     net.ipv6.conf.all.disable_ipv6 = 1
     net.ipv6.conf.default.disable_ipv6 = 1
     

   • Save the file and exit the text editor.

4. Apply the changes: Run the following command to make the settings take effect immediately:

   sysctl -p
   

5. Configure SSH to use IPv4 only:

   • Open the /etc/ssh/sshd_config file using a text editor.
   • Locate the AddressFamily directive and set it to inet:

     AddressFamily inet
     

   • If the AddressFamily directive is not present, add it to the file.

6. Restart SSH: Execute the following command to restart the SSH service and apply the changes:

   /scripts/restartsrv_sshd
   

Caution:

• Do not remove IPv6 kernel modules. Removing these modules can trigger warnings in cPanel & WHM, potentially hindering account creation and causing service disruptions.

Key Points to Remember

• Root Access: Ensure you’re logged in as the root user or have equivalent privileges to execute these commands.
• Potential Impacts: Disabling IPv6 might affect certain applications or services that rely on IPv6 connectivity.
• Expert Assistance: If you’re unsure about any of these steps or encounter any issues, don’t hesitate to seek help from your hosting provider’s support team or a qualified system administrator.

Conclusion

By following this guide, you can successfully disable IPv6 on your cPanel server, resolving potential networking issues and ensuring smooth operation. Remember to proceed with caution and seek expert assistance if needed.