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

I had the same error and google brought me to this question, so here is what I did, hoping that it helps others in a similar situation.

This is applicable for OS X.

Check in the Terminal which version of OpenSSL I had:

$ python3 -c "import ssl; print(ssl.OPENSSL_VERSION)"
>> OpenSSL 0.9.8zh 14 Jan 2016

As my version of OpenSSL was too old, the accepted answer did not work.

So I had to update OpenSSL. To do this, I updated Python to the latest version (from version 3.5 to version 3.6) with Homebrew, following some of the steps suggested here:

$ brew update
$ brew install openssl
$ brew install python3

Then I was having problems with the PATH and the version of python being used, so I just created a new virtualenv making sure that the newest version of python was taken:

$ virtualenv webapp --python=python3.6

Issue solved.