pip install pyOpenSSL

import socket
import ssl
import OpenSSL.crypto as crypto

dst = ('kele.im',443)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(dst)

# upgrade the socket to SSL without checking the certificate
# !!!! don't transfer any sensitive data over this socket !!!!
ctx = ssl.create_default_context()
ctx.check_hostname = False
ctx.verify_mode = ssl.CERT_NONE
s = ctx.wrap_socket(s, server_hostname=dst[0])

# get certificate
cert_bin = s.getpeercert(True)
x509 = crypto.load_certificate(crypto.FILETYPE_ASN1,cert_bin)
print("CN=" + x509.get_subject().CN)

来自https://stackoverflow.com/questions/45478536/python-getting-common-name-from-url-using-ssl-getpeercert