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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
tunnel: TChilkatSocket;
sshHostname: WideString;
sshPort: Integer;
success: Integer;
channel: IChilkatSocket;
maxWaitMs: Integer;
useTls: Integer;
bigEndian: Integer;
dt: TCkDateTime;
bLocalTime: Integer;

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

tunnel := TChilkatSocket.Create(Self);

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

// Connect to an SSH server and establish the SSH tunnel:
success := tunnel.SshOpenTunnel(sshHostname,sshPort);
if (success <> 1) then
  begin
    Memo1.Lines.Add(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.SshAuthenticatePw('mySshLogin','mySshPassword');
if (success <> 1) then
  begin
    Memo1.Lines.Add(tunnel.LastErrorText);
    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 := 0;
channel := tunnel.SshOpenChannel('time-c.nist.gov',37,useTls,maxWaitMs);
if (tunnel.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(tunnel.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
// 1 or 0 to indicate success.  If successful, the integer
// is obtained via the ReceivedInt property.
bigEndian := 1;
success := channel.ReceiveInt32(bigEndian);
if (success <> 1) then
  begin
    Memo1.Lines.Add(channel.LastErrorText);

    Exit;
  end;

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

// Show the current local date/time
bLocalTime := 1;
Memo1.Lines.Add('Current local date/time: ' + dt.GetAsRfc822(bLocalTime));

// Close the SSH channel.
success := channel.Close(maxWaitMs);
if (success <> 1) then
  begin
    Memo1.Lines.Add(channel.LastErrorText);

    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.
channel := tunnel.SshOpenChannel('time-a.nist.gov',37,useTls,maxWaitMs);
if (tunnel.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(tunnel.LastErrorText);
    Exit;
  end;

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

// 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 := channel.Close(maxWaitMs);
if (success <> 1) then
  begin
    Memo1.Lines.Add(channel.LastErrorText);

    Exit;
  end;

// Finally, close the SSH tunnel.
success := tunnel.SshCloseTunnel();
if (success <> 1) then
  begin
    Memo1.Lines.Add(tunnel.LastErrorText);
    Exit;
  end;

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