React Native Requires Chilkat v11.0.0+

POP3 SSH Tunneling (Port Forwarding)

Demonstrates how to connect to a POP3 server through an SSH tunnel. Reads a POP3 mailbox and display the FROM and SUBJECT header fields of each email. React Native

import { Email, MailMan } 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.

  // The mailman object is used for receiving (POP3) 
  // and sending (SMTP) email.
  const mailman = new MailMan();

  // The SSH hostname may be a hostname or an 
  // IP address, such as "192.168.1.108".
  // The port is typically 22 (the standard port for SSH).
  const sshHostname = 'sftp.example.com';
  const sshPort = 22;

  // Connect to an SSH server and establish the SSH tunnel:
  try {
    await mailman.sshOpenTunnelAsync(sshHostname, sshPort);
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  // Authenticate with the SSH server via a login/password
  // or with a public key.
  // This example demonstrates SSH password authentication.
  // Note: This is not authenticating with the POP3 server, it is
  // for authenticating with the SSH server, which is separate.
  try {
    await mailman.sshAuthenticatePwAsync('ssh_login', 'ssh_password');
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  // OK, the SSH tunnel is setup.  The mailman may
  // be used exactly the same as usual, except all communications
  // are now sent through the SSH tunnel.

  // The SSH tunnel may be kept open for any number of 
  // POP3 connections.  

  // Set the POP3 server's hostname
  mailman.mailHost = 'mail.my-pop3-server.com';

  // Set the POP3 settings for your POP3 server:
  mailman.popUsername = 'pop3_login';
  mailman.popPassword = 'pop3_password';
  mailman.mailPort = 995;
  mailman.popSsl = true;

  // Connect to the POP3 server through the already-established SSH tunnel:
  try {
    await mailman.pop3BeginSessionAsync();
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  // A visual inspection of the LastErrorText after
  // a successful POP3 connection will confirm the SSH tunneling.
  // Note: If the POP3 connection uses SSL/TLS, then the SSL/TLS 
  // secure channel will be wrapped within the SSH tunnel.
  console.log(mailman.lastErrorText);

  // How many messages are in the POP3 inbox?
  let numToDownload = await mailman.getMailboxCountAsync();
  if (numToDownload > 5) {
    numToDownload = 5;
  }

  if (numToDownload === 0) {
    console.log('No messages in the POP3 inbox.');
    return;
  }

  // Download a max of 5 messages
  const email = new Email();
  for (let i = 1; i <= numToDownload; i++) {
    try {
      await mailman.fetchOneAsync(false, 0, i, email);
    } catch {
      console.log(mailman.lastErrorText);
      return;
    }

    console.log(email.from);
    console.log(email.subject);
    console.log('----');
  }

  // Close the connection with the POP3 server, leaving the SSH tunnel open for subsequent POP3 connections.
  try {
    await mailman.pop3EndSessionAsync();
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  // Try connecting to a different POP3 server through the same aleady setup SSH tunnel:
  // Set the POP3 server's hostname
  mailman.mailHost = 'mail.my-pop3-server2.com';

  // Set the POP3 settings for your POP3 server:
  mailman.popUsername = 'pop3_login2';
  mailman.popPassword = 'pop3_password2';
  mailman.mailPort = 110;
  mailman.popSsl = false;

  try {
    await mailman.pop3BeginSessionAsync();
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  // Review the LastErrorText to see that the connection was made via the SSH tunnel:
  console.log(mailman.lastErrorText);

  try {
    await mailman.pop3EndSessionAsync();
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  // Close the SSH tunnel.
  try {
    await mailman.sshCloseTunnelAsync();
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }
}