Delphi DLL

Connect an SSH Tunnel Through a Jump Host

Demonstrates the Chilkat SshTunnel.ConnectThroughSsh method, which connects to an SSH 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 SSH hostname and port.

Background: This chains the tunnel through a "jump host" (bastion): the application reaches a gateway server, then tunnels onward to an SSH server that is only accessible from inside the network. Each hop authenticates separately with its own credentials. The result is a normal SshTunnel — still requiring its own authentication and BeginAccepting — whose transport is routed through the first connection.

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var
success: Boolean;
sshJump: HCkSsh;
sshPort: Integer;
password: PWideChar;
tunnel: HCkSshTunnel;
waitForThreadExit: Boolean;

begin
success := False;

//  Demonstrates the SshTunnel.ConnectThroughSsh method, which connects to an SSH 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 SSH hostname and port.

sshJump := CkSsh_Create();

//  Connect and authenticate to the jump host first.
sshPort := 22;
success := CkSsh_Connect(sshJump,'jump.example.com',sshPort);
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;

//  Set up the tunnel and connect to the target SSH server through the jump host.
tunnel := CkSshTunnel_Create();
CkSshTunnel_putDestHostname(tunnel,'db.internal.example.com');
CkSshTunnel_putDestPort(tunnel,5432);

success := CkSshTunnel_ConnectThroughSsh(tunnel,sshJump,'ssh.internal.example.com',sshPort);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSshTunnel__lastErrorText(tunnel));
    Exit;
  end;

//  Authenticate to the target SSH server (its own credentials).
success := CkSshTunnel_AuthenticatePw(tunnel,'mySshLogin',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSshTunnel__lastErrorText(tunnel));
    Exit;
  end;

//  After authenticating, call BeginAccepting to start listening for local connections to forward.

waitForThreadExit := True;
success := CkSshTunnel_CloseTunnel(tunnel,waitForThreadExit);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSshTunnel__lastErrorText(tunnel));
    Exit;
  end;

CkSsh_Disconnect(sshJump);

CkSsh_Dispose(sshJump);
CkSshTunnel_Dispose(tunnel);