the only working example of python socket with ssl

client.py

#!/usr/bin/python3

import socket
import ssl

host_addr = '127.0.0.1'
host_port = 8082
server_sni_hostname = 'example.com'
server_cert = 'server.crt'
client_cert = 'client.crt'
client_key = 'client.key'

context = ssl.create_default_context(ssl.Purpose.SERVER_AUTH, cafile=server_cert)
context.load_cert_chain(certfile=client_cert, keyfile=client_key)

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
conn = context.wrap_socket(s, server_side=False, server_hostname=server_sni_hostname)
conn.connect((host_addr, host_port))
print("SSL established. Peer: {}".format(conn.getpeercert()))
print("Sending: 'Hello, world!")
conn.send(b"Hello, world!")
print("Closing connection")
conn.close()

commands.txt

1) openssl req -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout server.key -out server.crt
 
2) openssl req -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout client.key -out client.crt

source: https://www.electricmonk.nl/log/2018/06/02/ssl-tls-client-certificate-verification-with-python-v3-4-sslcontext/

server.py

#!/usr/bin/python3

import socket
from socket import AF_INET, SOCK_STREAM, SO_REUSEADDR, SOL_SOCKET, SHUT_RDWR
import ssl

listen_addr = '127.0.0.1'
listen_port = 8082
server_cert = 'server.crt'
server_key = 'server.key'
client_certs = 'client.crt'

context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
context.verify_mode = ssl.CERT_REQUIRED
context.load_cert_chain(certfile=server_cert, keyfile=server_key)
context.load_verify_locations(cafile=client_certs)

bindsocket = socket.socket()
bindsocket.bind((listen_addr, listen_port))
bindsocket.listen(5)

while True:
    print("Waiting for client")
    newsocket, fromaddr = bindsocket.accept()
    print("Client connected: {}:{}".format(fromaddr[0], fromaddr[1]))
    conn = context.wrap_socket(newsocket, server_side=True)
    print("SSL established. Peer: {}".format(conn.getpeercert()))
    buf = b''  # Buffer to hold received client data
    try:
        while True:
            data = conn.recv(4096)
            if data:
                # Client sent us data. Append to buffer
                buf += data
            else:
                # No more data from client. Show buffer and close connection.
                print("Received:", buf)
                break
    finally:
        print("Closing connection")
        conn.shutdown(socket.SHUT_RDWR)
        conn.close()