(Swift) SSH Tunnel Inside another SSH Tunnel

Demonstrates how to create a TCP/IP socket connection through an SSH tunnel that is dynamic port forwarded through another SSH tunnel.

Note: This example requires Chilkat v11.0.0 or greater.

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func chilkatTest() {
    var success: Bool = false

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    let tunnel = CkoSshTunnel()!

    var sshHostname: String? = "www.ssh-serverA.com"
    var sshPort: Int = 22

    // Connect to an SSH server and establish the SSH tunnel:
    success = tunnel.connect(sshHostname, port: sshPort)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    // Authenticate with the SSH server via a login/password
    // or with a public key.  
    // This example demonstrates SSH password authentication.
    success = tunnel.authenticatePw("mySshLogin", password: "mySshPassword")
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    // Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
    // with dynamic port forwarding:
    tunnel.dynamicPortForwarding = true

    // We may optionally require that connecting clients authenticate with our SOCKS proxy server.
    // To do this, set an inbound username/password.  Any connecting clients would be required to 
    // use SOCKS5 with the correct username/password.
    // If no inbound username/password is set, then our SOCKS proxy server will accept both
    // SOCKS4 and SOCKS5 unauthenticated connections.

    tunnel.inboundSocksUsername = "chilkat123"
    tunnel.inboundSocksPassword = "password123"

    // Start the listen/accept thread to begin accepting SOCKS proxy client connections.
    // Listen on port 1080.
    success = tunnel.beginAccepting(1080)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    // Now that a background thread is running a SOCKS proxy server that forwards connections
    // through an SSH tunnel, it is possible to use any Chilkat implemented protocol that is SOCKS capable,
    // such as HTTP, POP3, SMTP, IMAP, FTP, Socket, etc.  The protocol may use SSL/TLS because the SSL/TLS
    // will be passed through the SSH tunnel to the end-destination.  Also, any number of simultaneous
    // connections may be routed through the SSH tunnel.

    let tunnelB = CkoSocket()!

    // Indicate that the socket object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
    tunnelB.socksHostname = "localhost"
    tunnelB.socksPort = 1080
    tunnelB.socksVersion = 5
    tunnelB.socksUsername = "chilkat123"
    tunnelB.socksPassword = "password123"

    // Open a new SSH tunnel through the existing tunnel (via what we treat as a SOCKS5 proxy,
    // but it is actually a dynamic port-forwarded SSH tunnel).
    success = tunnelB.sshOpenTunnel("www.ssh-serverB.com", sshPort: 22)
    if success == false {
        print("\(tunnelB.lastErrorText!)")
        return
    }

    // Authenticate with ssh-serverB.com
    success = tunnelB.sshAuthenticatePw("uname", sshPassword: "pwd")
    if success == false {
        print("\(tunnelB.lastErrorText!)")
        return
    }

    // OK, the SSH tunnel (within a tunnel) is setup.  Now open a channel within the tunnel.
    // Once the channel is obtained, the Socket API may
    // be used exactly the same as usual, except all communications
    // are sent through the channel in the SSH tunnel.
    // Any number of channels may be created from the same SSH tunnel.
    // Multiple channels may coexist at the same time.

    // Connect to an NIST time server and read the current date/time
    let channel = CkoSocket()!
    var maxWaitMs: Int = 4000
    var useTls: Bool = false
    success = tunnelB.sshNewChannel("time-c.nist.gov", port: 37, ssl: useTls, maxWaitMs: maxWaitMs, channel: channel)
    if success == false {
        print("\(tunnelB.lastErrorText!)")
        return
    }

    // The time server will send a big-endian 32-bit integer representing
    // the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
    // The ReceiveInt32 method will receive a 4-byte integer, but returns
    // true or false to indicate success.  If successful, the integer
    // is obtained via the ReceivedInt property.
    var bigEndian: Bool = true
    success = channel.receiveInt32(bigEndian)
    if success == false {
        print("\(channel.lastErrorText!)")
        return
    }

    let dt = CkoDateTime()!
    dt.setFromNtpTime(channel.receivedInt.intValue)

    // Show the current local date/time
    var bLocalTime: Bool = true
    print("Current local date/time: \(dt.getAsRfc822(bLocalTime)!)")

    // Close the SSH channel.
    success = channel.close(maxWaitMs)
    if success == false {
        print("\(channel.lastErrorText!)")
        return
    }

    // Stop the background listen/accept thread:
    var waitForThreadExit: Bool = true
    success = tunnel.stopAccepting(waitForThreadExit)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    // Close the SSH tunnel (would also kick any remaining connected clients).
    success = tunnel.close(waitForThreadExit)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }


}