表单的简单使用
按下submit，数据就会上报服务器
http数据：
POST /submit-form
Host: www.example.com
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/XX.X.XXXX.XX Safari/537.36
Content-Type: application/x-www-form-urlencoded
Content-Length: 45
Connection: keep-alive
username=admin&password=123456
接下来就是tcp打包，ip打包，链路打包，路由器打包
