Dart

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.

Dart

import 'package:chilkat/chilkat.dart';

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

  final ssh1 = CkSsh();

  // Connect directly to the 1st SSH server.
  try {
    ssh1.connect('serverssh1.com', 22);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Authenticate using login/password:
  try {
    ssh1.authenticatePw('ssh1Login', 'ssh1Password');
  } on ChilkatException catch (e) {
    print(e.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.
  final ssh2 = CkSsh();
  try {
    ssh2.connectThroughSsh(ssh1, 'serverssh2.com', 22);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Authenticate with ssh2...
  try {
    ssh2.authenticatePw('ssh2Login', 'ssh2Password');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final mailman = 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
  try {
    mailman.useSsh(ssh2);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Set the SMTP server.
  mailman.smtpHost = 'smtp.someserver.com';

  // Set the SMTP login/password (if required)
  mailman.smtpUsername = 'myUsername';
  mailman.smtpPassword = 'myPassword';

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

  email.subject = 'This is a test';
  email.body = 'This is a test';
  email.from = 'Chilkat Support <support@chilkatsoft.com>';
  email.addTo('Chilkat Admin', 'admin@chilkatsoft.com');

  try {
    mailman.sendEmail(email);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Close the connection with the server.  This closes the tunnel through ssh2.
  try {
    mailman.closeSmtpConnection();
  } on ChilkatException {
    print('Connection to SMTP server not closed cleanly.');
  }

  print('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();
}