HTTP Basic Authentication not working with Python 3

Question

I am trying to access an intranet site with HTTP Basic Authentication enabled.

Here's the code I'm using:

from bs4 import BeautifulSoup
import urllib.request, base64, urllib.error

request = urllib.request.Request(url)
string = '%s:%s' % ('username','password')

base64string = base64.standard_b64encode(string.encode('utf-8'))

request.add_header("Authorization", "Basic %s" % base64string)
try:
    u = urllib.request.urlopen(request)
except urllib.error.HTTPError as e:
    print(e)
    print(e.headers)

soup = BeautifulSoup(u.read(), 'html.parser')

print(soup.prettify())

But it doesn't work and fails with 401 Authorization required. I can't figure out why it's not working.

K G · Accepted Answer · 2017-11-09T12:03:35.253

The solution given here works without any modifications.

from bs4 import BeautifulSoup
import urllib.request

# create a password manager
password_mgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()

# Add the username and password.
# If we knew the realm, we could use it instead of None.
top_level_url = "http://example.com/foo/"
password_mgr.add_password(None, top_level_url, username, password)

handler = urllib.request.HTTPBasicAuthHandler(password_mgr)

# create "opener" (OpenerDirector instance)
opener = urllib.request.build_opener(handler)

# use the opener to fetch a URL
u = opener.open(url)

soup = BeautifulSoup(u.read(), 'html.parser')

The previous code works as well. You just have to decode the utf-8 encoded string otherwise the header contains a byte-sequence.

from bs4 import BeautifulSoup
import urllib.request, base64, urllib.error

request = urllib.request.Request(url)
string = '%s:%s' % ('username','password')

base64string = base64.standard_b64encode(string.encode('utf-8'))

request.add_header("Authorization", "Basic %s" % base64string.decode('utf-8'))
try:
    u = urllib.request.urlopen(request)
except urllib.error.HTTPError as e:
    print(e)
    print(e.headers)

soup = BeautifulSoup(u.read(), 'html.parser')

print(soup.prettify())

score 0 · Answer 2 · answered Nov 09 '17 at 10:33

0

UTF-8 encoding might not work. You can try to use ASCII or ISO-8859-1 encoding instead.

Also, try to access the intranet site with a web browser and check how the Authorization header is different from the one you are generating.

answered Nov 09 '17 at 10:33

StefanOS

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Thanks. I got the authentication to work using the instructions given [here](https://docs.python.org/3.1/howto/urllib2.html#id6). But for learning purposes, how do I check what header is being generated by the browser? – K G Nov 09 '17 at 10:37
Great that you got it working. You should submit the solution as an answer and accept it so others may benefit from it. – StefanOS Nov 09 '17 at 11:25
You can see the headers in browsers' dev tools. For example the Network tab in Chrome dev tools. https://stackoverflow.com/questions/4423061/view-http-headers-in-google-chrome – StefanOS Nov 09 '17 at 11:25
Ok I checked and the Authorization header I'm generating using the code above is exactly the same as what the browser is sending so I don't understand what the problem is. – K G Nov 09 '17 at 11:52
1

Ok I figured out what the problem is. Modifying my answer with the solution. – K G Nov 09 '17 at 11:58

score 0 · Answer 3 · edited Feb 15 '22 at 19:50

Encode using "ascii". This worked for me.

import base64
import urllib.request

url = "http://someurl/path"
username = "someuser"
token = "239487svksjdf08234"

request = urllib.request.Request(url)
base64string = base64.b64encode((username + ":" + token).encode("ascii"))
request.add_header("Authorization", "Basic {}".format(base64string.decode("ascii")))
response = urllib.request.urlopen(request)

response.read() # final response string

HTTP Basic Authentication not working with Python 3

3 Answers3