Delphi DLL

TCP Socket through SSH Tunnel (Port Forwarding)

See more Socket/SSL/TLS Examples

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.

Delphi 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
success: Boolean;
tunnel: HCkSocket;
sshHostname: PWideChar;
sshPort: Integer;
maxWaitMs: Integer;
useTls: Boolean;
channel: HCkSocket;
bigEndian: Boolean;
dt: HCkDateTime;
bLocalTime: Boolean;

begin
success := False;

// 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 = False) 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 = False) 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_Create();
success := CkSocket_SshNewChannel(tunnel,'time-c.nist.gov',37,useTls,maxWaitMs,channel);
if (success = 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 = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(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));
    Exit;
  end;

// 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.
success := CkSocket_SshNewChannel(tunnel,'time-a.nist.gov',37,useTls,maxWaitMs,channel);
if (success = 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));
    Exit;
  end;

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

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

CkSocket_Dispose(tunnel);
CkSocket_Dispose(channel);
CkDateTime_Dispose(dt);

end;