(Swift 3,4,5...) 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.

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    // 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.
    let mailman = CkoMailMan()!

    // 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: String? = "sftp.example.com"
    var sshPort: Int = 22

    // Connect to an SSH server and establish the SSH tunnel:
    var success: Bool = mailman.sshOpenTunnel(sshHostname, sshPort: sshPort)
    if success != true {
        print("\(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", sshPassword: "ssh_password")
    if success != true {
        print("\(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 {
        print("\(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.
    print("\(mailman.lastErrorText!)")

    // How many messages are in the POP3 inbox?
    var numToDownload: Int = mailman.getMailboxCount().intValue
    if numToDownload > 5 {
        numToDownload = 5
    }

    if numToDownload == 0 {
        return
    }

    // Download a max of 5 messages
    var i: Int
    var email: CkoEmail?
    for i = 1; i <= numToDownload; i++ {
        email = mailman.fetch(byMsgnum: i)
        if mailman.lastMethodSuccess == false {
            print("\(mailman.lastErrorText!)")
            return
        }

        print("\(email!.from!)")
        print("\(email!.subject!)")
        print("----")
        email = nil
    }

    // Close the connection with the POP3 server, leaving the SSH tunnel open for subsequent POP3 connections.
    success = mailman.pop3EndSession()
    if success != true {
        print("\(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 {
        print("\(mailman.lastErrorText!)")
        return
    }

    // Review the LastErrorText to see that the connection was made via the SSH tunnel:
    print("\(mailman.lastErrorText!)")

    success = mailman.pop3EndSession()
    if success != true {
        print("\(mailman.lastErrorText!)")
        return
    }

    // Close the SSH tunnel.
    success = mailman.sshCloseTunnel()
    if success != true {
        print("\(mailman.lastErrorText!)")
        return
    }


}