         config.append("           weight        = 1\n")
         config.append("        }\n\n");
         config.append("}\n\n");
-        if true{
+        if !natSwitch.isOn {
             config.append("proxy-etr-ipv4 {\n")
             config.append("        address     = \(petr)\n")
             config.append("        priority    = 1\n")

        config.append("# NAT Traversal configuration. \n")
        config.append("#   nat_traversal_support: check if the node is behind NAT\n\n")
        config.append("nat_traversal_support = \(natSwitch.isOn)\n\n\n")
        config.append("# Encapsulated Map-Requests are sent to this map-resolver\n")
        config.append("# You can define several map-resolvers. Encapsulated Map-Request messages will\n")
        config.append("# be sent to only one.\n")
        config.append("#   address: IPv4 or IPv6 address of the map resolver\n")
        config.append("map-resolver        = {\n")
        config.append("        \(defaults?.string(forKey: "mapResolver") ?? "")\n")
        config.append("}\n\n\n")
        config.append("# Map-Registers are sent to this map-server\n")
        config.append("# You can define several map-servers. Map-Register messages will be sent to all\n")
        config.append("# of them.\n")

    }
    
    @IBAction func saveButton(_ sender: Any) {
        var alert:UIAlertController? = nil;
        var hasAlert = false
        var message = ""
        if !validateIpAddress(ip: eidTextField.text!){
            message = message + "* Please enter a valid EID address\n"
            hasAlert = true
        }
        if !natSwitch.isOn {
            if !validateIpAddress(ip: mapResolverTextField.text!){
                message = message + "* Please enter a valid Map Resolver address\n"
                hasAlert = true
            }
            if !validateIpAddress(ip: proxyEtrAddressTextField.text!){
                message = message + "* Please enter a valid Proxy ETR address\n"
                hasAlert = true
            }
        }
        if !validateIpAddress(ip: mapServerTextField.text!){
            message = message + "* Please enter a valid Map Server address\n"
            hasAlert = true
        }
        if !validateIpAddress(ip: dnsServerTextField.text!){
            message = message + "* Please enter a valid DNS server address\n"
            hasAlert = true
        }
        
        if (iidTextField != nil){
            let iid = Int(iidTextField.text!)
            if iid == nil || iid! < 0 || iid! > 16777215 {
                message = message + "* Please enter a valid IID [0 - 16777215]\n"
                hasAlert = true
            }
        }else{
            iidTextField.text = "0"
        }
        
        if (hasAlert){
            alert = UIAlertController(title: "Invalid Configuration:",message: message, preferredStyle: .alert)
            alert!.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))
            self.present(alert!, animated: true)
        }else{
            saveConfig()
            saveLabel.text = "Configuration saved!"
        }
    }
    
