ssl.SSLError: tlsv1 alert protocol version

Question

I'm using the REST API for a Cisco CMX device, and trying to write Python code which makes a GET request to the API for information. The code is as follows and is the same as that in the file except with the necessary information changed.

from http.client import HTTPSConnection
from base64 import b64encode


# Create HTTPS connection
c = HTTPSConnection("0.0.0.0")

# encode as Base64
# decode to ascii (python3 stores as byte string, need to pass as ascii 
value for auth)
username_password = b64encode(b"admin:password").decode("ascii")
headers = {'Authorization': 'Basic {0}'.format(username_password)}

# connect and ask for resource
c.request('GET', '/api/config/v1/aaa/users', headers=headers)

# response
res = c.getresponse()

data = res.read()

However, I am continuously getting the following error:

Traceback (most recent call last):
  File "/Users/finaris/PycharmProjects/test/test/test.py", line 14, in <module>
    c.request('GET', '/api/config/v1/aaa/users', headers=headers)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/http/client.py", line 1106, in request
    self._send_request(method, url, body, headers)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/http/client.py", line 1151, in _send_request
    self.endheaders(body)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/http/client.py", line 1102, in endheaders
    self._send_output(message_body)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/http/client.py", line 934, in _send_output
    self.send(msg)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/http/client.py", line 877, in send
    self.connect()
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/http/client.py", line 1260, in connect
    server_hostname=server_hostname)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/ssl.py", line 377, in wrap_socket
    _context=self)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/ssl.py", line 752, in __init__
    self.do_handshake()
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/ssl.py", line 988, in do_handshake
    self._sslobj.do_handshake()
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/ssl.py", line 633, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLError: [SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:645)

I also tried updating OpenSSL but that had no effect.

Answer 1

The only thing you have to do is to install requests[security] in your virtualenv. You should not have to use Python 3 (it should work in Python 2.7). Moreover, if you are using a recent version of macOS, you don't have to use homebrew to separately install OpenSSL either.

$ virtualenv --python=/usr/bin/python tempenv  # uses system python
$ . tempenv/bin/activate
$ pip install requests
$ python
>>> import ssl
>>> ssl.OPENSSL_VERSION
'OpenSSL 0.9.8zh 14 Jan 2016'  # this is the built-in openssl
>>> import requests
>>> requests.get('https://api.github.com/users/octocat/orgs')
requests.exceptions.SSLError: HTTPSConnectionPool(host='api.github.com', port=443): Max retries exceeded with url: /users/octocat/orgs (Caused by SSLError(SSLError(1, u'[SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:590)'),))
$ pip install 'requests[security]'
$ python  # install requests[security] and try again
>>> import requests
>>> requests.get('https://api.github.com/users/octocat/orgs')
<Response [200]>

requests[security] allows requests to use the latest version of TLS when negotiating the connection. The built-in openssl on macOS supports TLS v1.2.

Before you install your own version of OpenSSL, ask this question: how is Google Chrome loading https://github.com?

Answer 2

I encountered this exact issue when I attempted gem install bundler, and I was confused by all the Python responses (since I was using Ruby). Here was my exact error:

ERROR:  Could not find a valid gem 'bundler' (>= 0), here is why:
          Unable to download data from https://rubygems.org/ - SSL_connect returned=1 errno=0 state=SSLv2/v3 read server hello A: tlsv1 alert protocol version (https://rubygems.org/latest_specs.4.8.gz)

My solution: I updated Ruby to the most recent version (2.6.5). Problem solved.