AFAIK，你做不到.
您无权访问PC(出于安全原因)，并且如果可以的话，这种行为也不是行为良好的网站.

即使可以，也无法阻止用户拔出网络电缆，拔出其PC插头，或者关闭路由器.

您将不得不寻找另一种方式！抱歉.

AFAIK, you can''t do it.
You have no access to the PC (for security reasons) and that kind of behavior would not be that of a well behaved site if you could.

Even if you could, you can''t prevent the user pulling then network cable out, unplugging his PC, or turning off the router.

You will have to find another way! Sorry.