Pascal (Lazarus/Delphi)

TCP or TLS over Multiple Hop SSH to Remote Server

See more Socket/SSL/TLS Examples

Demonstrates how to use the Chilkat Socket API to connect to a remote server (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => DestinationServer

The ConnectThroughSsh and UseSsh methods are added in Chilkat version 9.5.0.55 to accomplish this task.

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.Ssh,
  Chilkat.Socket;

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

procedure RunDemo;
var
  success: Boolean;
  ssh1: TSsh;
  ssh2: TSsh;
  socket: TSocket;
  useTls: Boolean;
  maxWaitMillisec: Integer;
  responseStatusLine: string;
  responseHeaderLine: string;
  remainderOfHeader: string;

begin
  success := False;

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

  ssh1 := TSsh.Create;

  //  Connect directly to the 1st SSH server.
  success := ssh1.Connect('serverssh1.com',22);
  if (success <> True) then
    begin
      WriteLn(ssh1.LastErrorText);
      Exit;
    end;

  //  Authenticate using login/password:
  success := ssh1.AuthenticatePw('ssh1Login','ssh1Password');
  if (success <> True) then
    begin
      WriteLn(ssh1.LastErrorText);
      Exit;
    end;

  //  Connect through the 1st SSH connection to reach a 2nd SSH server.
  //  Note: Any number of SSH connections may be simultaneously tunneled through a single
  //  existing SSH connection.
  ssh2 := TSsh.Create;
  success := ssh2.ConnectThroughSsh(ssh1,'serverssh2.com',22);
  if (success <> True) then
    begin
      WriteLn(ssh2.LastErrorText);
      Exit;
    end;

  //  Authenticate with ssh2...
  success := ssh2.AuthenticatePw('ssh2Login','ssh2Password');
  if (success <> True) then
    begin
      WriteLn(ssh2.LastErrorText);
      Exit;
    end;

  socket := TSocket.Create;

  //  Tell the socket object to connect to our destination server though the ssh2 tunnel (which itself is routed through ssh1).
  //  The connection looks like this:  ApplicationSocket(TLS) => ServerSSH1 => ServerSSH2 => DestinationServer
  success := socket.UseSsh(ssh2);
  if (success <> True) then
    begin
      WriteLn(socket.LastErrorText);
      Exit;
    end;

  //  Connect using TLS to www.chilkatsoft.com
  //  We could also tunnel a bare TCP connection by specifying port 80 with useTls = False.
  useTls := True;
  maxWaitMillisec := 20000;
  success := socket.Connect('www.chilkatsoft.com',443,useTls,maxWaitMillisec);
  if (success <> True) then
    begin
      WriteLn(socket.LastErrorText);
      Exit;
    end;

  //  Once the multiple hop SSH tunneled connection is setup,  the socket programming
  //  is identical to the normal case where we have a direct connection.

  //  Tell the socket object that all text is to be sent in the utf-8 encoding,
  //  and the text received is assumed to be utf-8.
  socket.StringCharset := 'utf-8';

  //  Send an HTTP HEAD request:
  success := socket.SendString('HEAD / HTTP/1.1' + #13#10 + 'Host: www.chilkatsoft.com' + #13#10 + #13#10);
  if (success <> True) then
    begin
      WriteLn(socket.LastErrorText);
      Exit;
    end;

  //  Wait a maximum of 4 seconds while no data is forthcoming:
  socket.MaxReadIdleMs := 4000;

  //  Get the 1st response line, which should be "HTTP/1.1 200 OK"
  responseStatusLine := socket.ReceiveToCRLF();
  if (socket.LastMethodSuccess <> True) then
    begin
      WriteLn(socket.LastErrorText);
      Exit;
    end;

  WriteLn('StatusLine: ' + responseStatusLine);

  //  Now get the 1st line of the response header:
  responseHeaderLine := socket.ReceiveToCRLF();
  if (socket.LastMethodSuccess <> True) then
    begin
      WriteLn(socket.LastErrorText);
      Exit;
    end;

  WriteLn('HeaderLine: ' + responseHeaderLine);

  //  Now read the remainder of the response header by reading until a double CRLF is seen:
  remainderOfHeader := socket.ReceiveUntilMatch(#13#10 + #13#10);
  if (socket.LastMethodSuccess <> True) then
    begin
      WriteLn(socket.LastErrorText);
      Exit;
    end;

  WriteLn('Remainder: ' + remainderOfHeader);

  //  Close the connection with the server.  This closes the tunnel through ssh2.
  //  Wait a max of 20 seconds (20000 millsec)
  success := socket.Close(20000);

  //  Close the connection with ssh2.  (This closes the the tunnel through ssh1.)
  //  The connection with ssh1 is still alive, and may be used for more connections.
  ssh2.Disconnect();

  ssh1.Disconnect();


  ssh1.Free;
  ssh2.Free;
  socket.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.