(Node.js) 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.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

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.
    var mailman = new chilkat.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).
    var sshHostname = "sftp.example.com";
    var sshPort = 22;

    // Connect to an SSH server and establish the SSH tunnel:
    var success = mailman.SshOpenTunnel(sshHostname,sshPort);
    if (success !== true) {
        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.
    success = mailman.SshAuthenticatePw("ssh_login","ssh_password");
    if (success !== true) {
        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:
    success = mailman.Pop3BeginSession();
    if (success !== true) {
        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?
    var numToDownload = mailman.GetMailboxCount();
    if (numToDownload > 5) {
        numToDownload = 5;
    }

    if (numToDownload == 0) {
        return;
    }

    // Download a max of 5 messages
    var i;
    // email: Email
    var email;
    for (i = 1; i <= numToDownload; i++) {
        email = mailman.FetchByMsgnum(i);
        if (mailman.LastMethodSuccess == false) {
            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.
    success = mailman.Pop3EndSession();
    if (success !== true) {
        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;

    success = mailman.Pop3BeginSession();
    if (success !== true) {
        console.log(mailman.LastErrorText);
        return;
    }

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

    success = mailman.Pop3EndSession();
    if (success !== true) {
        console.log(mailman.LastErrorText);
        return;
    }

    // Close the SSH tunnel.
    success = mailman.SshCloseTunnel();
    if (success !== true) {
        console.log(mailman.LastErrorText);
        return;
    }


}

chilkatExample();