Chapter 6 ■ tLS/SSL
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if name == 'main':
parser = argparse.ArgumentParser(description='Protect a socket with TLS')
parser.add_argument('host', help='hostname or IP address')
parser.add_argument('port', type=int, help='TCP port number')
parser.add_argument('-a', metavar='cafile', default=None,
help='authority: path to CA certificate PEM file')
parser.add_argument('-c', metavar='certfile', default=None,
help='path to PEM file with client certificate')
parser.add_argument('-C', metavar='ciphers', default='ALL',
help='list of ciphers, formatted per OpenSSL')
parser.add_argument('-p', metavar='PROTOCOL', default='SSLv23',
help='protocol version (default: "SSLv23")')
parser.add_argument('-s', metavar='certfile', default=None,
help='run as server: path to certificate PEM file')
parser.add_argument('-d', action='store_true', default=False,
help='debug mode: do not hide "ctypes" exceptions')
parser.add_argument('-v', action='store_true', default=False,
help='verbose: print out remote certificate')
args = parser.parse_args()
address = (args.host, args.port)
protocol = lookup('PROTOCOL_', args.p)
context = ssl.SSLContext(protocol)
context.set_ciphers(args.C)
context.check_hostname = False
if (args.s is not None) and (args.c is not None):
parser.error('you cannot specify both -c and -s')
elif args.s is not None:
context.verify_mode = ssl.CERT_OPTIONAL
purpose = ssl.Purpose.CLIENT_AUTH
context.load_cert_chain(args.s)
else:
context.verify_mode = ssl.CERT_REQUIRED
purpose = ssl.Purpose.SERVER_AUTH
if args.c is not None:
context.load_cert_chain(args.c)
if args.a is None:
context.load_default_certs(purpose)
else:
context.load_verify_locations(args.a)
print()
ssl_sock = open_tls(context, address, args.s)
cert = describe(ssl_sock, args.host, args.s, args.d)
print()
if args.v:
pprint(cert)
You can most easily learn the command-line options supported by this tool by running it with the standard –h
help option. It tries to expose all of the major features of an SSLContext through its command-line options so that you
can experiment with them and learn how they affect negotiation. For example, you can investigate how the default