React Native Requires Chilkat v11.0.0+

IMAP SSH Tunneling (Port Forwarding)

Demonstrates how to setup and use an SSH tunnel for IMAP. React Native

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

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

  const imap = new Imap();

  // 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 = 'www.mysshserver.com';
  const sshPort = 22;

  // Connect to an SSH server and establish the SSH tunnel:
  try {
    await imap.sshOpenTunnelAsync(sshHostname, sshPort);
  } catch {
    console.log(imap.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 IMAP server, it is
  // for authenticating with the SSH server, which is separate.
  try {
    await imap.sshAuthenticatePwAsync('mySshLogin', 'mySshPassword');
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

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

  // Connect to an IMAP server via the SSH tunnel.
  // Because the SSH tunnel has been previously setup,
  // this does not establish a direct connection with the IMAP
  // server.  It directs the SSH server to establish the connection.

  // In this example, the IMAP server requires SSL/TLS.  The TLS connection
  // will be enclosed within the SSH tunnel.
  imap.ssl = true;
  imap.port = 993;
  try {
    await imap.connectAsync('imap.my-imap-server.com');
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  // Authenticate with the IMAP server via the SSH tunnel.
  try {
    await imap.loginAsync('myLogin', 'myPassword');
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  // Select an IMAP mailbox
  try {
    await imap.selectMailboxAsync('Inbox');
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  // How many messages in Inbox?
  const msgCount = imap.numMessages;
  if (msgCount === 0) {
    console.log('No messages found.');
    return;
  }

  let upperBound = 10;
  if (msgCount < upperBound) {
    upperBound = msgCount;
  }

  // Download up to the 1st 10 messages.
  const email = new Email();
  const bUid = false;
  for (let i = 1; i <= upperBound; i++) {

    try {
      await imap.fetchEmailAsync(false, i, bUid, email);
    } catch {
      console.log(imap.lastErrorText);
      return;
    }

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

  // Disconnect from the IMAP server.
  // The SSH tunnel remains open.
  try {
    await imap.disconnectAsync();
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  // It is possible to re-use the existing SSH tunnel for the next connection:
  try {
    await imap.connectAsync('imap.my-imap-server2.com');
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

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

  try {
    await imap.disconnectAsync();
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  // Finally, close the SSH tunnel.
  try {
    await imap.sshCloseTunnelAsync();
  } catch {
    console.log(imap.lastErrorText);
    return;
  }

  console.log('IMAP SSH tunneling example completed.');
}