How to Fix FTP Service Failure in Plesk with IPv6 Disabled

If you’re running a Plesk server on Linux and have disabled IPv6, might encounter an issue where the FTP Service Failure in Plesk with IPv6 Disabled. This problem is triggered when the xinetd attempts to launch the FTP daemon using IPv6, despite the protocol being disabled system-wide.

You might see the following error in your server logs (typically found in journalctl, /var/log/messages, or systemctl status xinetd):

xinetd[503]: socket creation failed (Address family not supported by protocol (errno = 97)). service = ftp
xinetd[503]: Service ftp failed to start and is deactivated.

The FTP service remains inactive, rendering you unable to connect via FTP.

The issue is due to xinetd attempting to bind the FTP service using the IPv6 address family. If IPv6 is disabled at the kernel level, this fails with error 97, “Address family not supported by protocol”.

Resolution: Force xinetd to Use IPv4

Step 1: Connect to your server via SSH

ssh root@server-ip

Step 2: Edit the FTP service configuration

Open the /etc/xinetd.d/ftp_psa file with your preferred text editor. Example using vim editor:

vim /etc/xinetd.d/ftp_psa

Look for this line:

flags = IPv6

Replace it with:

flags = IPv4

Your updated configuration should look like this:

service ftp
{
        flags           = IPv4
        disable         = no
        socket_type     = stream
        protocol        = tcp
        wait            = no
        user            = root
        instances       = UNLIMITED
        server          = /usr/sbin/in.proftpd
        server_args     = -c /etc/proftpd.conf
}

This file may be overwritten during a future Plesk update, so you might want to create a script or automation to reapply this fix if needed.

Step 3: Restart the xinetd service

After saving the changes, restart xinetd to apply them:

systemctl start xinetd

To verify it’s running:

systemctl status xinetd

If everything is configured correctly, the FTP service should now be active and accepting connections over IPv4.

Conclusion

While disabling IPv6 can improve security or simplify networking in certain environments, it can cause compatibility issues like FTP Service Failure in Plesk with IPv6 Disabled when services expect IPv6 support by default. By explicitly telling xinetd to use IPv4, you ensure your FTP service continues to work even with IPv6 turned off.

Need expert help fixing FTP service failures on your Plesk server with IPv6 disabled? Contact Skynats today for reliable Plesk Server Management Services and fast support!