Swift

FTP through SSH Tunnel with Dynamic Port Forwarding

See more FTP Examples

Demonstrates how to start a background thread that runs a portable SSH tunnel w/ dynamic port forwarding that the foreground thread can be used for establishing FTP sessions through an SSH tunnel.

Note: Some developers may be accustomed to starting an stunnel.exe proxy from https://www.stunnel.org. The stunnel.exe is not necessary here. Chilkat's background thread fulfills the task of what the external stunnel.exe does. Therefore, your application is self-contained, meaning that it can run anywhere because the SSH tunnel proxy is built-in.

Swift

func chilkatTest() {
    var success: Bool = false

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

    success = false

    let tunnel = CkoSshTunnel()!

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

    // Connect to an SSH server and establish the SSH tunnel:
    success = tunnel.connect(hostname: sshHostname, port: sshPort)
    if success != true {
        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(login: "mySshLogin", password: "mySshPassword")
    if success != true {
        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(listenPort: 1080)
    if success != true {
        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, 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 ftp = CkoFtp2()!

    // Indicate that the HTTP object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
    ftp.socksHostname = "localhost"
    // The SocksPort must equal the port passed to BeginAccepting above.
    ftp.socksPort = 1080
    ftp.socksVersion = 5
    // The SOCKS5 login/password set here must equal the InboundSocksUsername/Password set above.
    ftp.socksUsername = "chilkat123"
    ftp.socksPassword = "password123"

    // This is the actual FTP server domain or IP address, and the login/password for the user account on the destination FTP server.
    ftp.hostname = "ftp.someFtpServer.com"
    ftp.username = "myLogin"
    ftp.password = "myPassword"
    ftp.authTls = true

    // Connect and login (via the SSH tunnel) to the FTP server.
    success = ftp.connect()
    if success != true {
        print("\(ftp.lastErrorText!)")
        return
    }

    // Change to the remote directory where the file is located.
    // This step is only necessary if the file is not in the root directory
    // for the FTP account.
    success = ftp.changeRemoteDir(relativeDirPath: "junk")
    if success != true {
        print("\(ftp.lastErrorText!)")
        return
    }

    var localFilename: String? = "c:/temp/hamlet.xml"
    var remoteFilename: String? = "hamlet.xml"

    // Download a file.  (the data connection is also automatically established through the 
    // SSH tunnel using dynamic port forwarding..)
    success = ftp.getFile(remoteFilename: remoteFilename, localPath: localFilename)
    if success != true {
        print("\(ftp.lastErrorText!)")
        return
    }

    // The disconnect is disconnecting with the FTP server and closes the SSH tunnel.
    // The background tunnel thread is still running, and may be used for subsequent FTP connections,
    // or even connections for any other purpose, such as HTTP, IMAP, SMTP, POP3, etc.
    success = ftp.disconnect()

    // When the app is finished with the tunnel, it can cleanup..

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

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


}