Delphi DLL

Connect to an SFTP Server Through a Jump Host

Demonstrates the Chilkat SFtp.ConnectThroughSsh method, which connects to an SFTP server through an already connected and authenticated Ssh object. The first argument is the jump-host Ssh object, and the second and third are the destination hostname and port.

Background: This is the "jump host" (bastion) pattern: the application connects to a reachable gateway, then tunnels onward to an SFTP server that is only accessible from inside the network. Each hop authenticates separately with its own credentials. The result is a normal SFtp object — still requiring its own authentication and InitializeSftp — that happens to be routed through the first connection.

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var
success: Boolean;
sshJump: HCkSsh;
port: Integer;
password: PWideChar;
sftp: HCkSFtp;

begin
success := False;

//  Demonstrates the SFtp.ConnectThroughSsh method, which connects to an SFTP server through an
//  already connected and authenticated Ssh object (a jump host).  The 1st argument is the Ssh
//  object, and the 2nd and 3rd are the destination hostname and port.

sshJump := CkSsh_Create();

//  Connect and authenticate to the jump host first.
port := 22;
success := CkSsh_Connect(sshJump,'jump.example.com',port);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(sshJump));
    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(sshJump,'myJumpLogin',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(sshJump));
    Exit;
  end;

//  Connect to the SFTP server through the jump host.
sftp := CkSFtp_Create();
success := CkSFtp_ConnectThroughSsh(sftp,sshJump,'sftp.internal.example.com',port);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

//  Authenticate to the SFTP server (its own credentials), then initialize SFTP.
success := CkSFtp_AuthenticatePw(sftp,'mySshLogin',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

success := CkSFtp_InitializeSftp(sftp);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;
Memo1.Lines.Add('Connected to the SFTP server through the jump host.');

CkSFtp_Disconnect(sftp);
CkSsh_Disconnect(sshJump);

CkSsh_Dispose(sshJump);
CkSFtp_Dispose(sftp);