React Native Requires Chilkat v11.0.0+

POP3 over Multiple Hop SSH

Demonstrates how to read POP3 email (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => POP3Server

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 POP3 server though the ssh2 tunnel (which itself is routed through ssh1).
  // The connection looks like this:  Application => ServerSSH1 => ServerSSH2 => POP3Server
  try {
    mailman.useSsh(ssh2);
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  // Set the POP3 server's hostname
  mailman.mailHost = 'pop.example.com';

  // Set the POP3 login/password.
  mailman.popUsername = 'myLogin';
  mailman.popPassword = 'myPassword';

  // Establish the POP3 connection through the ssh2 tunnel.
  try {
    await mailman.pop3BeginSessionAsync();
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  // Get the number of messages in the mailbox.
  const numMessages = await mailman.getMailboxCountAsync();

  const email = new Email();
  let i = 1;
  while (i <= numMessages) {
    // Fetch by the message number (not by the UIDL)
    try {
      await mailman.fetchOneAsync(false, 0, i, email);
    } catch {
      console.log(mailman.lastErrorText);
      return;
    }

    console.log(`${email.from}: ${email.subject}\n`);

    i++;
  }

  // Close the connection with the POP3 server.  (This closes the tunnel through ssh2)
  // The connection with ssh2 is still alive, and may be used for more connections.
  await mailman.pop3EndSessionAsync();

  // 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();
}