en
upgrade tftp://<hostname|IP>[:port]/path/file
upgrade ftp://<user>:<passwd>@<hostname|IP>[:port]/path/file
upgrade sftp://<user>@<hostname|IP>[:port]>/path/file
upgrade http://<hostname|IP>[:port]/path/file
upgrade cf:/path/file
upgrade usb1:/path/file
upgrade usb2:/path/file