Lazarus Pascal

Send an SSH IGNORE Message

Demonstrates the Chilkat Ssh.SendIgnore method, which sends an SSH IGNORE message. It takes no arguments. The server does not reply, but a successful send helps confirm the connection is still writable. No channel is required.

Background: The SSH IGNORE message is discarded by the peer by design; its usefulness is as a lightweight keep-alive or liveness probe. Because it exercises the actual write path, a successful SendIgnore is stronger evidence than CheckConnection that the link is still usable, without side effects on any channel.

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Lazarus Pascal

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;
  ssh: TSsh;
  sshPort: Integer;
  password: string;

begin
  success := False;

  //  Demonstrates the Ssh.SendIgnore method, which sends an SSH IGNORE message.  It takes no
  //  arguments.  The server does not reply, but a successful send helps confirm the connection is
  //  still writable.  No channel is required.

  ssh := TSsh.Create;

  //  Connect to the SSH server.  Port 22 is the usual SSH port.
  sshPort := 22;
  success := ssh.Connect('ssh.example.com',sshPort);
  if (success = False) then
    begin
      WriteLn(ssh.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 := ssh.AuthenticatePw('mySshLogin',password);
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Send an IGNORE message to verify the connection is still writable.
  success := ssh.SendIgnore();
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;
  WriteLn('IGNORE message sent.');

  ssh.Disconnect();


  ssh.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.