Python requests WWW-Authenticate missing in headers

I’m trying to access the WWW-Authenticate header after a GET request using Python’s requests library. When I do this in Postman it returns it but in Python it doesn’t.

Python:

import requests
from requests.auth import HTTPBasicAuth

headers = {
    # "Python-Token": "<calculated when request is sent>",
    # "Host": "<calculated when request is sent>",
    "Accept": "application/json, */*", 
    "User-Agent": "PythonRuntime/3.9.7",
    # "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.106 Safari/537.36",
    "Accept-Encoding": "gzip, deflate, br", 
    "Connection": "keep-alive", 
    "Access-Control-Expose-Headers": "x-WWW-Authenticate",
    'x-requested-with': 'XMLHttpRequest',
    'sec-fetch-site': 'same-origin',
    'sec-fetch-mode': 'cors',
    "Authorization": "Bearer"
}
site = "https://YourSPOSiteURL/_vti_bin/client.svc/"
auth = HTTPBasicAuth('[e-mail]', 'somepasswordhere')
headers = dict( requests.get(f"{site}/_vti_bin/client.svc/", auth=auth).headers )

headers:

{'Cache-Control': 'private, max-age=0',
 'Content-Length': '0',
 'Content-Security-Policy': "frame-ancestors 'self' teams.microsoft.com "
                            '*.teams.microsoft.com *.skype.com '
                            '*.teams.microsoft.us local.teams.office.com '
                            '*.powerapps.com *.yammer.com '
                            '*.officeapps.live.com *.office.com '
                            '*.stream.azure-test.net *.microsoftstream.com '
                            '*.dynamics.com;',
 'Date': 'Fri, 04 Feb 2022 14:53:16 GMT',
 'Expires': 'Thu, 20 Jan 2022 14:53:16 GMT',
 'Last-Modified': 'Fri, 04 Feb 2022 14:53:16 GMT',
 'MS-CV': 'xxxxxxxxxxxxx.0',
 'MicrosoftSharePointTeamServices': 'xx.x.x.xxxxx',
 'P3P': 'CP="ALL IND DSP COR ADM CONo CUR CUSo IVAo IVDo PSA PSD TAI TELo OUR '
        'SAMo CNT COM INT NAV ONL PHY PRE PUR UNI"',
 'SPRequestGuid': '697da8340-a0d3-30123-9fc9-98c88419387426',
 'Server': 'Microsoft-IIS/10.0',
 'Strict-Transport-Security': 'max-age=31536000',
 'Vary': 'Origin',
 'X-AspNet-Version': '4.0.xxxxx',
 'X-Content-Type-Options': 'nosniff',
 'X-FRAME-OPTIONS': 'SAMEORIGIN',
 'X-MS-InvokeApp': '1; RequireReadOnly',
 'X-Powered-By': 'ASP.NET',
 'X-SharePointHealthScore': '2',
 'request-id': '697da8340-a0d3-30123-9fc9-98c88419387426'}

Postman:

I’ve tried every headers param I can find but can’t seem to return the WWW-Authenticate response header which I need…any help would be much appreciated.

Edit:

Within Postman, it looks to be the Host key in the headers get request that’s generating the WWW-Authenticate in the response headers. When I remove it (in Postman) I get only a handful of headers in the response headers. But how would I replicate this in Python’s requests library?

This is what it says when hovering over the Host header in GET:

Answer

Pass the request headers to the server:

# requests.get(f"{site}/_vti_bin/client.svc/", auth=auth)
requests.get(f"{site}/_vti_bin/client.svc/", headers=headers, auth=auth)