Pascal (Lazarus/Delphi)

SSH Tunnel Inside another SSH Tunnel

See more SSH Tunnel Examples

Demonstrates how to create a TCP/IP socket connection through an SSH tunnel that is dynamic port forwarded through another SSH tunnel. 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.CkDateTime,
  Chilkat.Socket;

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

procedure RunDemo;
var
  success: Boolean;
  tunnel: TSshTunnel;
  sshHostname: string;
  sshPort: Integer;
  tunnelB: TSocket;
  channel: TSocket;
  maxWaitMs: Integer;
  useTls: Boolean;
  bigEndian: Boolean;
  dt: TCkDateTime;
  bLocalTime: Boolean;
  waitForThreadExit: Boolean;

begin
  success := False;

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

  tunnel := TSshTunnel.Create;

  sshHostname := 'www.ssh-serverA.com';
  sshPort := 22;

  //  Connect to an SSH server and establish the SSH tunnel:
  success := tunnel.Connect(sshHostname,sshPort);
  if (success = False) 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 = False) 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 = False) 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, Socket, 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.

  tunnelB := TSocket.Create;

  //  Indicate that the socket object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
  tunnelB.SocksHostname := 'localhost';
  tunnelB.SocksPort := 1080;
  tunnelB.SocksVersion := 5;
  tunnelB.SocksUsername := 'chilkat123';
  tunnelB.SocksPassword := 'password123';

  //  Open a new SSH tunnel through the existing tunnel (via what we treat as a SOCKS5 proxy,
  //  but it is actually a dynamic port-forwarded SSH tunnel).
  success := tunnelB.SshOpenTunnel('www.ssh-serverB.com',22);
  if (success = False) then
    begin
      WriteLn(tunnelB.LastErrorText);
      Exit;
    end;

  //  Authenticate with ssh-serverB.com
  success := tunnelB.SshAuthenticatePw('uname','pwd');
  if (success = False) then
    begin
      WriteLn(tunnelB.LastErrorText);
      Exit;
    end;

  //  OK, the SSH tunnel (within a tunnel) is setup.  Now open a channel within the tunnel.
  //  Once the channel is obtained, the Socket API may
  //  be used exactly the same as usual, except all communications
  //  are sent through the channel in the SSH tunnel.
  //  Any number of channels may be created from the same SSH tunnel.
  //  Multiple channels may coexist at the same time.

  //  Connect to an NIST time server and read the current date/time
  channel := TSocket.Create;
  maxWaitMs := 4000;
  useTls := False;
  success := tunnelB.SshNewChannel('time-c.nist.gov',37,useTls,maxWaitMs,channel);
  if (success = False) then
    begin
      WriteLn(tunnelB.LastErrorText);
      Exit;
    end;

  //  The time server will send a big-endian 32-bit integer representing
  //  the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
  //  The ReceiveInt32 method will receive a 4-byte integer, but returns
  //  True or False to indicate success.  If successful, the integer
  //  is obtained via the ReceivedInt property.
  bigEndian := True;
  success := channel.ReceiveInt32(bigEndian);
  if (success = False) then
    begin
      WriteLn(channel.LastErrorText);
      Exit;
    end;

  dt := TCkDateTime.Create;
  dt.SetFromNtpTime(channel.ReceivedInt);

  //  Show the current local date/time
  bLocalTime := True;
  WriteLn('Current local date/time: ' + dt.GetAsRfc822(bLocalTime));

  //  Close the SSH channel.
  success := channel.Close(maxWaitMs);
  if (success = False) then
    begin
      WriteLn(channel.LastErrorText);
      Exit;
    end;

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

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


  tunnel.Free;
  tunnelB.Free;
  channel.Free;
  dt.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.