func configureVPN(serverAddress: String, username: String, password: String) {
    var configData:Data = Data.init()
    self.getCertificate{certificate in
        configData = certificate!
        
        guard
            //If we want to read from a file
 //                let configData = self.readFile(name: "vtest2"),
            let providerManager = self.providerManager
        else {
            return
        }
        
        self.providerManager?.loadFromPreferences { error in
            if error == nil {
                let tunnelProtocol = NETunnelProviderProtocol()
                tunnelProtocol.username = username
                tunnelProtocol.serverAddress = serverAddress
                tunnelProtocol.providerBundleIdentifier = self.providerId // bundle id of the network extension target
                tunnelProtocol.providerConfiguration = ["ovpn": configData]
                tunnelProtocol.disconnectOnSleep = false
                providerManager.protocolConfiguration = tunnelProtocol
                providerManager.localizedDescription = "Slyfone Guard" // the title of the VPN profile which will appear on Settings
                providerManager.isEnabled = true
                providerManager.saveToPreferences(completionHandler: { (error) in
                    if error == nil  {
                        providerManager.loadFromPreferences(completionHandler: { (error) in
                            do {
                                try providerManager.connection.startVPNTunnel(options: nil) // starts the VPN tunnel.
                            } catch let error {
                                print(error.localizedDescription)
                            }
                        })
                    }
                })
            }
        }
    }
}