Pascal (Lazarus/Delphi)

FTP through SSH Tunnel with Dynamic Port Forwarding

See more FTP Examples

Demonstrates how to start a background thread that runs a portable SSH tunnel w/ dynamic port forwarding that the foreground thread can be used for establishing FTP sessions through an SSH tunnel.

Note: Some developers may be accustomed to starting an stunnel.exe proxy from https://www.stunnel.org. The stunnel.exe is not necessary here. Chilkat's background thread fulfills the task of what the external stunnel.exe does. Therefore, your application is self-contained, meaning that it can run anywhere because the SSH tunnel proxy is built-in.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.SshTunnel,
  Chilkat.Ftp2;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  tunnel: TSshTunnel;
  sshHostname: string;
  sshPort: Integer;
  ftp: TFtp2;
  localFilename: string;
  remoteFilename: string;
  waitForThreadExit: Boolean;

begin
  success := False;

  //  This example assumes the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  success := False;

  tunnel := TSshTunnel.Create;

  sshHostname := 'sftp.example.com';
  sshPort := 22;

  //  Connect to an SSH server and establish the SSH tunnel:
  success := tunnel.Connect(sshHostname,sshPort);
  if (success <> True) then
    begin
      WriteLn(tunnel.LastErrorText);
      Exit;
    end;

  //  Authenticate with the SSH server via a login/password
  //  or with a public key.  
  //  This example demonstrates SSH password authentication.
  success := tunnel.AuthenticatePw('mySshLogin','mySshPassword');
  if (success <> True) then
    begin
      WriteLn(tunnel.LastErrorText);
      Exit;
    end;

  //  Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
  //  with dynamic port forwarding:
  tunnel.DynamicPortForwarding := True;

  //  We may optionally require that connecting clients authenticate with our SOCKS proxy server.
  //  To do this, set an inbound username/password.  Any connecting clients would be required to 
  //  use SOCKS5 with the correct username/password.
  //  If no inbound username/password is set, then our SOCKS proxy server will accept both
  //  SOCKS4 and SOCKS5 unauthenticated connections.

  tunnel.InboundSocksUsername := 'chilkat123';
  tunnel.InboundSocksPassword := 'password123';

  //  Start the listen/accept thread to begin accepting SOCKS proxy client connections.
  //  Listen on port 1080.
  success := tunnel.BeginAccepting(1080);
  if (success <> True) then
    begin
      WriteLn(tunnel.LastErrorText);
      Exit;
    end;

  //  Now that a background thread is running a SOCKS proxy server that forwards connections
  //  through an SSH tunnel, it is possible to use any Chilkat implemented protocol that is SOCKS capable,
  //  such as HTTP, POP3, SMTP, IMAP, FTP, etc.  The protocol may use SSL/TLS because the SSL/TLS
  //  will be passed through the SSH tunnel to the end-destination.  Also, any number of simultaneous
  //  connections may be routed through the SSH tunnel.

  ftp := TFtp2.Create;

  //  Indicate that the HTTP object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
  ftp.SocksHostname := 'localhost';
  //  The SocksPort must equal the port passed to BeginAccepting above.
  ftp.SocksPort := 1080;
  ftp.SocksVersion := 5;
  //  The SOCKS5 login/password set here must equal the InboundSocksUsername/Password set above.
  ftp.SocksUsername := 'chilkat123';
  ftp.SocksPassword := 'password123';

  //  This is the actual FTP server domain or IP address, and the login/password for the user account on the destination FTP server.
  ftp.Hostname := 'ftp.someFtpServer.com';
  ftp.Username := 'myLogin';
  ftp.Password := 'myPassword';
  ftp.AuthTls := True;

  //  Connect and login (via the SSH tunnel) to the FTP server.
  success := ftp.Connect();
  if (success <> True) then
    begin
      WriteLn(ftp.LastErrorText);
      Exit;
    end;

  //  Change to the remote directory where the file is located.
  //  This step is only necessary if the file is not in the root directory
  //  for the FTP account.
  success := ftp.ChangeRemoteDir('junk');
  if (success <> True) then
    begin
      WriteLn(ftp.LastErrorText);
      Exit;
    end;

  localFilename := 'c:/temp/hamlet.xml';
  remoteFilename := 'hamlet.xml';

  //  Download a file.  (the data connection is also automatically established through the 
  //  SSH tunnel using dynamic port forwarding..)
  success := ftp.GetFile(remoteFilename,localFilename);
  if (success <> True) then
    begin
      WriteLn(ftp.LastErrorText);
      Exit;
    end;

  //  The disconnect is disconnecting with the FTP server and closes the SSH tunnel.
  //  The background tunnel thread is still running, and may be used for subsequent FTP connections,
  //  or even connections for any other purpose, such as HTTP, IMAP, SMTP, POP3, etc.
  success := ftp.Disconnect();

  //  When the app is finished with the tunnel, it can cleanup..

  //  Stop the background listen/accept thread:
  waitForThreadExit := True;
  success := tunnel.StopAccepting(waitForThreadExit);
  if (success <> True) then
    begin
      WriteLn(tunnel.LastErrorText);
      Exit;
    end;

  //  Close the SSH tunnel (would also kick any remaining connected clients).
  success := tunnel.CloseTunnel(waitForThreadExit);
  if (success <> True) then
    begin
      WriteLn(tunnel.LastErrorText);
      Exit;
    end;


  tunnel.Free;
  ftp.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.