xsupplinent不能认证成功？

问题如下：

装好后运行:
xsupplicant -i eth0  -u XXXXXXX -p xxxxxxx
提示错误:
Username override!  Using username XXXXXXXX
Password passed in from command line!  (This isn't very secure!)
Error : libnet_select_device(): No network interfaces found.

什么含义呢?怎么才能解决啊?
这是校园网认证客户端的