React Native

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.

React Native

import { Email, MailMan, Ssh } from '@chilkat/react-native'

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

  const ssh1 = new Ssh();

  // Connect directly to the 1st SSH server.
  try {
    await ssh1.connectAsync('serverssh1.com', 22);
  } catch {
    console.log(ssh1.lastErrorText);
    return;
  }

  // Authenticate using login/password:
  try {
    await ssh1.authenticatePwAsync('ssh1Login', 'ssh1Password');
  } catch {
    console.log(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.
  const ssh2 = new Ssh();
  try {
    await ssh2.connectThroughSshAsync(ssh1, 'serverssh2.com', 22);
  } catch {
    console.log(ssh2.lastErrorText);
    return;
  }

  // Authenticate with ssh2...
  try {
    await ssh2.authenticatePwAsync('ssh2Login', 'ssh2Password');
  } catch {
    console.log(ssh2.lastErrorText);
    return;
  }

  const mailman = new MailMan();

  // 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);
  } catch {
    console.log(mailman.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
  const email = new Email();

  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 {
    await mailman.sendEmailAsync(email);
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  // Close the connection with the server.  This closes the tunnel through ssh2.
  try {
    await mailman.closeSmtpConnectionAsync();
  } catch {
    console.log('Connection to SMTP server not closed cleanly.');
  }

  console.log('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();
}