If you're unable to connect to your Plesk server via FTP and see an error indicating an "Insecure server" that "does not support FTP over TLS," it usually means a service conflict on the FTP port (21). This guide will walk you through identifying and resolving the issue.
What Are vsftpd and xinetd?
vsftpd (Very Secure FTP Daemon) is a popular, secure FTP server for UNIX systems, while xinetd is an Internet services daemon that manages network connections for various services, including FTP, in Linux. In Plesk environments, xinetd typically manages FTP, but conflicts can arise if vsftpd or other services are running on the same port (21), causing connection issues.
Prerequisites
- Access to the server via SSH with root privileges.
- Familiarity with basic Linux commands and an FTP client like FileZilla.
Symptoms
If this issue occurs, you may see errors similar to the following in your FTP client log (note: messages vary by client):
Status: Connecting to 203.0.113.2:21...
Status: Connection established, waiting for welcome message...
Status: Insecure server, it does not support FTP over TLS.
Command: USER testuser
Response: 331 Please specify the password.
Command: PASS *********
Response: 530 Login incorrect.
Error: Critical error: Could not connect to server
Verifying the Issue
- Check which service is running on port 21 (the default FTP port) with the command:
This command displays active services on port 21. Ifss -tlpn | grep :21vsftpdor another service appears, it may be causing the conflict. - Check for errors in
xinetdlogs:
If you see an error likejournalctl -u xinetdinetd[1113]: bind failed (Address already in use (errno = 98)). service = ftp, it confirms a port conflict.
Cause
The error occurs because another package, such as vsftpd, is running on port 21, blocking xinetd from starting the FTP service on that port.
Resolution Steps
- Stop the Conflicting Service
Connect to the server over SSH and stop the conflicting service on port 21. In this example, the service isvsftpd:systemctl stop vsftpd - Remove the Conflicting Package
To prevent the service from restarting, remove it from your system:- For RHEL-based systems, run:
dnf remove vsftpd - For Debian-based systems, run:
apt remove vsftpd
- For RHEL-based systems, run:
- Restart xinetd
After removing the conflict, restart thexinetdservice to re-establish FTP functionality:systemctl restart xinetd
Additional Tips
- Use a Test Environment: Always apply changes in a test environment before deploying to production.
- Check Plesk Documentation: Ensure that you reference the latest Plesk and Linux documentation for version-specific commands and compatibility.
Disclaimer
Be cautious when removing packages as it can affect other dependencies on your server. Always verify changes in a test environment first.
