OpenSSL - Raspberry Pi4 failing to communicate to server on windows system - python-3.x

Question

As the title states I get an error trying to communicate from a Raspberry PI 4 and windows system using an SSL connection.
The current client script works perfectly on windows to a server application running on windows.
This is the client script:
from OpenSSL import SSL
import sys, os, select, socket, time
ctx = SSL.Context(SSL.SSLv23_METHOD)
sock = SSL.Connection(ctx, socket.socket(socket.AF_INET, socket.SOCK_STREAM))
sock.connect(('10.0.0.84', 443))
stri = 'hello\r\n'
tobyte = bytes(stri,'utf-8')
print(tobyte)
buf = sock.recv(4096)
while True:
sock.send(tobyte)
time.sleep(60)
The error I get on Raspberry Pi 4:
Traceback (most recent call last): File
"/home/pi/Documents/scripts/openssltest.py", line 15, in
buf = sock.recv(4096)
File "/usr/lib/python3/dist-packages/OpenSSL/SSL.py", line 1791, in recv
self._raise_ssl_error(self._ssl, result) File "/usr/lib/python3/dist-packages/OpenSSL/SSL.py", line 1647, in
_raise_ssl_error
_raise_current_error() File "/usr/lib/python3/dist-packages/OpenSSL/_util.py", line 54, in
exception_from_error_queue
raise exception_type(errors) OpenSSL.SSL.Error: [('SSL routines', 'ssl_choose_client_version', 'unsupported protocol')]
I have the same version of OpenSSL running on the Raspberry Pi and Windows PC
One thing I noticed in Visual Studio Code (for the Raspberry Pi) is that the sock.send() is not recognised but sock.sendall() is. VSC in windows is showing sock.send() as an option.
I am using OpenSSL version 1.1.1k and python 3.7.3 on the Raspberry PI. OpenSSL 1.1.1k and python 3.9.6 on windows. All devices are running on the same network
I have not written the server application but uses a self signed certificate.
Any suggestions would be much appreciated

Answer 1

Adding #mti2935 comment as the answer as this fixed my problem. Just to help anyone in the future
('SSL routines', 'ssl_choose_client_version', 'unsupported protocol')
usually means the server will only allow connections using certain
SSL/TLS protocols (e.g. TLS1.2 or above), but the client does not
support any of the protocols that the server requires (e.g. client
supports TLS1.0 or lower). Can you try connecting to the server from
the command line of the PI, by doing openssl s_client -connect
10.0.0.84:443? Does it connect? If so, what protocol does it use?
The problem was that my client was using a protocol that the server did not support SSLv23_METHOD. Changed the protocol to SSL.TLSv1_METHOD.
Corrected code:
from OpenSSL import SSL
import sys, os, select, socket, time
ctx = SSL.Context(SSL.TLSv1_METHOD)
sock = SSL.Connection(ctx, socket.socket(socket.AF_INET, socket.SOCK_STREAM))
sock.connect(('10.0.0.84', 443))
stri = 'hello\r\n'
tobyte = bytes(stri,'utf-8')
print(tobyte)
buf = sock.recv(4096)
print(buf)
while True:
sock.send(tobyte)
time.sleep(5)