Pascal (Lazarus/Delphi)

Connect to an SSH Server Through Another (Jump Host)

Demonstrates the Chilkat Ssh.ConnectThroughSsh method, which connects to a second SSH server through an already connected and authenticated Ssh object. The first argument is the first (jump-host) Ssh object, and the second and third are the destination hostname and port.

Background: This is SSH chaining through a "jump host" (bastion): the application connects to a reachable gateway, then tunnels onward to a target that is only accessible from inside the network. Each hop is authenticated separately with its own credentials. The result is a normal Ssh object for the target that happens to be routed through the first connection.

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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;

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

procedure RunDemo;
var
  success: Boolean;
  sshJump: TSsh;
  sshPort: Integer;
  password: string;
  sshTarget: TSsh;

begin
  success := False;

  //  Demonstrates the Ssh.ConnectThroughSsh method, which connects to a second SSH server through
  //  an already connected and authenticated Ssh object (a jump host).  The 1st argument is the
  //  first Ssh object, and the 2nd and 3rd are the destination hostname and port.

  sshJump := TSsh.Create;

  //  Connect and authenticate to the first SSH server (the jump host).
  sshPort := 22;
  success := sshJump.Connect('jump.example.com',sshPort);
  if (success = False) then
    begin
      WriteLn(sshJump.LastErrorText);
      Exit;
    end;

  //  Normally you would not hard-code the password in source.  You should instead obtain it
  //  from an interactive prompt, environment variable, or a secrets vault.
  password := 'mySshPassword';

  success := sshJump.AuthenticatePw('jumpUser',password);
  if (success = False) then
    begin
      WriteLn(sshJump.LastErrorText);
      Exit;
    end;

  //  Connect to the target SSH server through the jump host.
  sshTarget := TSsh.Create;
  success := sshTarget.ConnectThroughSsh(sshJump,'target.example.com',sshPort);
  if (success = False) then
    begin
      WriteLn(sshTarget.LastErrorText);
      Exit;
    end;

  //  Authenticate to the target server (separate credentials).
  success := sshTarget.AuthenticatePw('targetUser',password);
  if (success = False) then
    begin
      WriteLn(sshTarget.LastErrorText);
      Exit;
    end;
  WriteLn('Connected to the target through the jump host.');

  sshTarget.Disconnect();
  sshJump.Disconnect();


  sshJump.Free;
  sshTarget.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.