(Java) SMTP over Multiple Hop SSH

Demonstrates how to send email (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => SmtpServer

The ConnectThroughSsh and UseSsh methods are added in Chilkat version 9.5.0.55 to accomplish this task.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkSsh ssh1 = new CkSsh();

    // Connect directly to the 1st SSH server.
    boolean success = ssh1.Connect("serverssh1.com",22);
    if (success != true) {
        System.out.println(ssh1.lastErrorText());
        return;
        }

    // Authenticate using login/password:
    success = ssh1.AuthenticatePw("ssh1Login","ssh1Password");
    if (success != true) {
        System.out.println(ssh1.lastErrorText());
        return;
        }

    // Connect through the 1st SSH connection to reach a 2nd SSH server.
    // Note: Any number of SSH connections may be simultaneously tunneled through a single
    // existing SSH connection.
    CkSsh ssh2 = new CkSsh();
    success = ssh2.ConnectThroughSsh(ssh1,"serverssh2.com",22);
    if (success != true) {
        System.out.println(ssh2.lastErrorText());
        return;
        }

    // Authenticate with ssh2...
    success = ssh2.AuthenticatePw("ssh2Login","ssh2Password");
    if (success != true) {
        System.out.println(ssh2.lastErrorText());
        return;
        }

    CkMailMan mailman = new CkMailMan();

    // Tell the mailman object to connect to the SMTP server though the ssh2 tunnel (which itself is routed through ssh1).
    // The connection looks like this:  Application => ServerSSH1 => ServerSSH2 => SMTPServer
    success = mailman.UseSsh(ssh2);
    if (success != true) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    // Set the SMTP server.
    mailman.put_SmtpHost("smtp.someserver.com");

    // Set the SMTP login/password (if required)
    mailman.put_SmtpUsername("myUsername");
    mailman.put_SmtpPassword("myPassword");

    // Create a new email object
    CkEmail email = new CkEmail();

    email.put_Subject("This is a test");
    email.put_Body("This is a test");
    email.put_From("Chilkat Support <support@chilkatsoft.com>");
    success = email.AddTo("Chilkat Admin","admin@chilkatsoft.com");

    success = mailman.SendEmail(email);
    if (success != true) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    // Close the connection with the server.  This closes the tunnel through ssh2.
    success = mailman.CloseSmtpConnection();
    if (success != true) {
        System.out.println("Connection to SMTP server not closed cleanly.");
        }

    System.out.println("Mail Sent!");

    // Close the connection with ssh2.  (This closes the the tunnel through ssh1.)
    // The connection with ssh1 is still alive, and may be used for more connections.
    ssh2.Disconnect();

    ssh1.Disconnect();
  }
}