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

[senthil]

Applicable to:

• Plesk for Linux

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.
  
  Code Select Expand
  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)
  
  Code Select Expand
  # ss -tlpn | grep :21
LISTEN 0 64 *:21 : users:(("vsftpd",pid=1660,fd=5))
• xinetd is running, but the following message appears in journalctl
  
  Code Select Expand
  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.

• Connect to the server over SSH
• Stop the service running on port 21
  
  Code Select Expand
  # systemctl stop vsftpd
• Remove its package with the appropriate command for the system
  RHEL-based
  
  Code Select Expand
  # dnf remove vsftpdDebian-based
  
  Code Select Expand
  # apt remove vsftpd
• Restart the xinetd service
  
  Code Select Expand
  # systemctl restart xinetd