虚拟机安装Kali linux 参考地址：
http://www.360doc.com/content/14/1006/11/6692392_414734398.shtml
http://jingyan.baidu.com/article/9faa7231b1ffb9473d28cb7e.html
http://www.linuxidc.com/Linux/2016-11/137594.htm
Kali linux 安装后，SSH已安装不可访问：参考：
http://jingyan.baidu.com/article/7f766daf9cdbd24100e1d053.html
