Delphi DLL Requires Chilkat v11.0.0+

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

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
//  1 or 0 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);