Skip to content

Instantly share code, notes, and snippets.

@gdamjan
Last active May 11, 2023 08:07
Embed
What would you like to do?
Python script to check on SSL certificates
# -*- encoding: utf-8 -*-
# requires a recent enough python with idna support in socket
# pyopenssl, cryptography and idna
from OpenSSL import SSL
from cryptography import x509
from cryptography.x509.oid import NameOID
import idna
from socket import socket
from collections import namedtuple
HostInfo = namedtuple(field_names='cert hostname peername', typename='HostInfo')
HOSTS = [
('damjan.softver.org.mk', 443),
('expired.badssl.com', 443),
('wrong.host.badssl.com', 443),
('ca.ocsr.nl', 443),
('faß.de', 443),
('самодеј.мкд', 443),
]
def verify_cert(cert, hostname):
# verify notAfter/notBefore, CA trusted, servername/sni/hostname
cert.has_expired()
# service_identity.pyopenssl.verify_hostname(client_ssl, hostname)
# issuer
def get_certificate(hostname, port):
hostname_idna = idna.encode(hostname)
sock = socket()
sock.connect((hostname, port))
peername = sock.getpeername()
ctx = SSL.Context(SSL.SSLv23_METHOD) # most compatible
ctx.check_hostname = False
ctx.verify_mode = SSL.VERIFY_NONE
sock_ssl = SSL.Connection(ctx, sock)
sock_ssl.set_connect_state()
sock_ssl.set_tlsext_host_name(hostname_idna)
sock_ssl.do_handshake()
cert = sock_ssl.get_peer_certificate()
crypto_cert = cert.to_cryptography()
sock_ssl.close()
sock.close()
return HostInfo(cert=crypto_cert, peername=peername, hostname=hostname)
def get_alt_names(cert):
try:
ext = cert.extensions.get_extension_for_class(x509.SubjectAlternativeName)
return ext.value.get_values_for_type(x509.DNSName)
except x509.ExtensionNotFound:
return None
def get_common_name(cert):
try:
names = cert.subject.get_attributes_for_oid(NameOID.COMMON_NAME)
return names[0].value
except x509.ExtensionNotFound:
return None
def get_issuer(cert):
try:
names = cert.issuer.get_attributes_for_oid(NameOID.COMMON_NAME)
return names[0].value
except x509.ExtensionNotFound:
return None
def print_basic_info(hostinfo):
s = '''» {hostname} « … {peername}
\tcommonName: {commonname}
\tSAN: {SAN}
\tissuer: {issuer}
\tnotBefore: {notbefore}
\tnotAfter: {notafter}
'''.format(
hostname=hostinfo.hostname,
peername=hostinfo.peername,
commonname=get_common_name(hostinfo.cert),
SAN=get_alt_names(hostinfo.cert),
issuer=get_issuer(hostinfo.cert),
notbefore=hostinfo.cert.not_valid_before,
notafter=hostinfo.cert.not_valid_after
)
print(s)
def check_it_out(hostname, port):
hostinfo = get_certificate(hostname, port)
print_basic_info(hostinfo)
import concurrent.futures
if __name__ == '__main__':
with concurrent.futures.ThreadPoolExecutor(max_workers=4) as e:
for hostinfo in e.map(lambda x: get_certificate(x[0], x[1]), HOSTS):
print_basic_info(hostinfo)
@Damien455
Copy link

Would it be possible to convert the cert to a byte string or an instance of asn1crypto.x509.Certificate please?

@dimazarno
Copy link

Hi, the script is useful, but it's possible put these values: ('damjan.softver.org.mk', 443), ('expired.badssl.com', 443), ('wrong.host.badssl.com', 443), ('ca.ocsr.nl', 443), ('faß.de', 443), ('самодеј.мкд', 443), inside a text file? I mean exist an elegant way to read lines of file into list?

you can change HOSTS into this:

HOSTS = []

for line in hosts_file:
host, port = line.strip().split(':')
HOSTS.append((host, int(port)))

@panofish
Copy link

I really appreciate that you took the time to share this with the world... super useful !!! Thank you.

@leejhn
Copy link

leejhn commented May 11, 2023

Thank you so much for being so helpful.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment