Can't connect over FTP: Insecure server, it does not support FTP over TLS.

Symptoms

• Unable to connect via FTP with the following errors.

  Note: These error logs are from FileZilla. The messages may be different on other FTP clients.

  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

• Another service is running on port 21 instead of xinetd (the FTP server used by Plesk)

  # ss -tlpn | grep :21
  LISTEN 0 64 *:21 : users:(("vsftpd",pid=1660,fd=5))

• xinetd is running, but the following message appears in journalctl

  inetd[1113]: bind failed (Address already in use (errno = 98)). service = ftp
  xinetd[1113]: Service ftp failed to start and is deactivated.

Cause

Another package is preventing xinetd from starting by occupying its port.

Resolution

Remove the package running on port 21 and restart xinetd

Note: This example uses vsftpd as the service running on port 21. The name of the service and exact steps may vary.

1. Connect to the server over SSH

2. Stop the service running on port 21

   # systemctl stop vsftpd

3. Remove its package with the appropriate command for the system

   • RHEL-based

     # dnf remove vsftpd

   • Debian-based

     # apt remove vsftpd

4. Restart the xinetd service

   # systemctl restart xinetd