The callback connection feature of USBDeviceShare allows you to establish connection between the server and the client even when the server cannot accept incoming connections. The server will not be able to accept incoming connections if it does not have a directly accessible IP address (example: when server is behind a router or a firewall).
In callback connection mode, the client waits for the connection while the server initiates the connection request. See http://www.sysnucleus.com/usbshare/help/callbackconnection.htm to know more about callback connections.
Download and try the 15 days evaluation copy of USBDeviceShare USB over Ethernet software from http://www.sysnucleus.com/usbshare/usbshare_download.html.