This is a browser plugin to generate barcode image, so you can copy the barcode string and get the image, then you can use Packetracer barcode scanning function. Thanks Luxin for developing this usefull plugin.
For Google Chrome, download and install directly. Download Link
For Firefox, you need download Google Chrome extensions manager firstly and install it.

Plugin official site:
http://www.killwin.com/articles/312.html