About cookies about python crawler

I am trying to grap the message from a web page. Anything goes well, but I face a problem that one parameter in cookies changes when I login in different time. I try to goole to find anwser, but I got nothing. If u could help, many thanks.

  import requests

  cookies = {
  'ASP.NET_SessionId': 'ry1gstswj0pu013efuzgdsct',
  '**********1': 'outid=::ffff:10.102.14.251&failnum=2&faildate=2016-11-23 22:03:13',
  '.NECEID': '1',
  '.NEWCAPEC1': '$newcapec$:zh-CN_CAMPUS',
  '.ASPXAUTSSM': '3606B64104F915DC863C94D88EFC73D68531EBAE6C1DEBACCD1C4B7EB1B2537EBCAEC3B4D4C613557A6F2F1EEBEA1A5205C4551C1F868A947FC21C2D9FD0AB80C1BAE6F64776DECAA34CC8CACAEBB46D2D1D47AE127F4602044097BE10603209922E12FAD25B0436F5B7C63550A016F0',
  }

and the .ASPXAUTSSM changes all the time.

when I login, it sets the .ASPXAUTSSM Login

when I send request, it will send the cookies as well. send request

How can I get the value of .ASPXAUTSSM.
Thanks again!