Artisinal Handcrafted HTTP 3 picoctfwp

题目描述:We found a hidden flag server hiding behind a proxy, but the proxy has some… interesting ideas of what qualifies someone to make HTTP requests. Looks like you’ll have to do this one by hand. Try connecting via nc 2018shell2.picoctf.com 2651, and use the proxy to send HTTP requests to flag.local. We’ve also recovered a username and a password for you to use on the login page: realbusinessuser/potoooooooo.
大概意思是通过用户名密码realbusinessuser/potoooooooo.发送http请求给flag.local,需要content-type,content-length参数

得到set-cookie，再以get方式发送，

得到flag