import requests
import base64
url="http://123.206.87.240:8002/web6/"
res=requests.get(url)
flag=res.headers['flag'] #获取header的falg字段
flag=base64.b64decode(flag).decode('utf8')[-8:] #后边八个数
flag=base64.b64decode(flag)
res1=requests.post(url,{'margin':flag},cookies=res.cookies)#要提交cookie
print(res1.text)