(Delphi DLL) TCP Socket through SSH Tunnel (Port Forwarding)

Demonstrates using Chilkat Socket to communicate to a TCP service through an SSH tunnel. This example will connect to an NIST time server and (using the old Time Protocol (RFC 868)), will read the current GMT time.

Note: This is not necessarily a recommended means for getting the current date/time. The most commonly used time protocol is the Network Time Protocol (RFC-1305). The intent of this example is to show how TCP communications can occur through an SSH tunnel.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, CkDateTime, Socket;

...

procedure TForm1.Button1Click(Sender: TObject);
var
tunnel: HCkSocket;
sshHostname: PWideChar;
sshPort: Integer;
success: Boolean;
channel: HCkSocket;
maxWaitMs: Integer;
useTls: Boolean;
bigEndian: Boolean;
dt: HCkDateTime;
bLocalTime: Boolean;

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

tunnel := CkSocket_Create();

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

// Connect to an SSH server and establish the SSH tunnel:
success := CkSocket_SshOpenTunnel(tunnel,sshHostname,sshPort);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tunnel));
    Exit;
  end;

// Authenticate with the SSH server via a login/password
// or with a public key.
// This example demonstrates SSH password authentication.
success := CkSocket_SshAuthenticatePw(tunnel,'mySshLogin','mySshPassword');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tunnel));
    Exit;
  end;

// OK, the SSH 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

maxWaitMs := 4000;
useTls := False;
channel := CkSocket_SshOpenChannel(tunnel,'time-c.nist.gov',37,useTls,maxWaitMs);
if (CkSocket_getLastMethodSuccess(tunnel) = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tunnel));
    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 := CkSocket_ReceiveInt32(channel,bigEndian);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(channel));
    CkSocket_Dispose(channel);
    Exit;
  end;

dt := CkDateTime_Create();
CkDateTime_SetFromNtpTime(dt,CkSocket_getReceivedInt(channel));

// Show the current local date/time
bLocalTime := True;
Memo1.Lines.Add('Current local date/time: ' + CkDateTime__getAsRfc822(dt,bLocalTime));

// Close the SSH channel.
success := CkSocket_Close(channel,maxWaitMs);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(channel));
    CkSocket_Dispose(channel);
    Exit;
  end;

CkSocket_Dispose(channel);

// It is possible to create a new channel from the existing SSH tunnel for the next connection:
// Any number of channels may be created from the same SSH tunnel.
// Multiple channels may coexist at the same time.
channel := CkSocket_SshOpenChannel(tunnel,'time-a.nist.gov',37,useTls,maxWaitMs);
if (CkSocket_getLastMethodSuccess(tunnel) = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tunnel));
    Exit;
  end;

// Review the LastErrorText to see that the connection was made via the SSH tunnel:
Memo1.Lines.Add(CkSocket__lastErrorText(tunnel));

// Close the connection to time-a.nist.gov.  This is actually closing our channel
// within the SSH tunnel, but keeps the tunnel open for the next port-forwarded connection.
success := CkSocket_Close(channel,maxWaitMs);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(channel));
    CkSocket_Dispose(channel);
    Exit;
  end;

CkSocket_Dispose(channel);

// Finally, close the SSH tunnel.
success := CkSocket_SshCloseTunnel(tunnel);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tunnel));
    Exit;
  end;

Memo1.Lines.Add('TCP SSH tunneling example completed.');

CkSocket_Dispose(tunnel);
CkDateTime_Dispose(dt);

end;