SSH Tunnel (Port Forwarding via direct-tcpip Channel)

See more SSH Examples

Demonstrates creating an SSH tunnel to a remote host:port using a direct-tcpip channel. Data written to the channel is forwarded by the SSH server to the target, and data read back is whatever the target sent. This example tunnels a simple HTTP GET request to a web server.

var
success: Boolean;
ssh: HCkSsh;
hostname: PWideChar;
port: Integer;
password: PWideChar;
targetHost: PWideChar;
targetPort: Integer;
channelNum: Integer;
httpReq: PWideChar;
caseSensitive: Boolean;
matchStr: PWideChar;
responseHeader: PWideChar;
pollTimeoutMs: Integer;
numBytesRead: Integer;
htmlBody: PWideChar;

begin
success := False;

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

//  Demonstrates creating an SSH tunnel to a remote host:port using a direct-tcpip channel.
//  Data written to the channel is forwarded by the SSH server to the target host:port, and data
//  read from the channel is whatever the target sent back.

ssh := CkSsh_Create();

hostname := 'ssh.example.com';
port := 22;
success := CkSsh_Connect(ssh,hostname,port);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    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 := CkSsh_AuthenticatePw(ssh,'mySshLogin',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  Ask the SSH server to connect onward to this host:port.  The target is resolved by the SSH
//  server, not by this computer, so it must be reachable from the server's network.  The target
//  need not be a web server -- it can be any TCP service.
targetHost := 'www.chilkatsoft.com';
targetPort := 80;
channelNum := CkSsh_OpenDirectTcpIpChannel(ssh,targetHost,targetPort);
if (channelNum < 0) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  Send a simple HTTP GET request through the tunnel.
httpReq := 'GET /xyz123.html HTTP/1.1' + #13#10 + 'Host: www.chilkatsoft.com' + #13#10 + #13#10;
success := CkSsh_ChannelSendString(ssh,channelNum,httpReq,'utf-8');
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
//  which means no limit -- without it, this call waits forever if the received data never
//  contains a match.
CkSsh_putReadTimeoutMs(ssh,15000);

//  An HTTP response header ends with a blank line, so receive until a double CRLF is seen.
//  The method may read beyond the match, but it stops waiting as soon as the match appears.
caseSensitive := False;
matchStr := #13#10 + #13#10;
success := CkSsh_ChannelReceiveUntilMatch(ssh,channelNum,matchStr,'utf-8',caseSensitive);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  GetReceivedTextS removes everything through and including the match, which is exactly the
//  response header.
responseHeader := CkSsh__getReceivedTextS(ssh,channelNum,matchStr,'utf-8');
if (CkSsh_getLastMethodSuccess(ssh) = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;
Memo1.Lines.Add('---- HTTP Response Header ----');
Memo1.Lines.Add(responseHeader);

//  The body may already have arrived along with the header.  Poll briefly for anything more.
//  A -2 return simply means nothing further arrived, which is not an error here.
pollTimeoutMs := 200;
numBytesRead := CkSsh_ChannelPoll(ssh,channelNum,pollTimeoutMs);
if (numBytesRead = -1) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

htmlBody := CkSsh__getReceivedText(ssh,channelNum,'utf-8');
if (CkSsh_getLastMethodSuccess(ssh) = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;
Memo1.Lines.Add('---- HTML BODY ----');
Memo1.Lines.Add(htmlBody);

success := CkSsh_ChannelSendClose(ssh,channelNum);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

CkSsh_Disconnect(ssh);

CkSsh_Dispose(ssh);