check_dane_smtp

   1 #!/usr/bin/python3
   2 #
   3 #
   4
   5 from __future__ import print_function
   6
   7 import sys
   8 import argparse
   9 import logging
  10
  11 from socket import socket, AF_INET6, AF_INET, create_connection
  12 from ssl import SSLContext, PROTOCOL_TLSv1_2, CERT_REQUIRED, cert_time_to_seconds, SSLError, CertificateError, create_default_context
  13 from unbound import ub_ctx, ub_strerror
  14
  15 from check_dane.tlsa import verify_tlsa_record
  16 from check_dane.cert import verify_certificate, add_certificate_options
  17
  18 def init_connection(sslcontext, args):
  19     host = args.Host
  20
  21     if args.ssl:
  22         port = 465 if args.port == 0 else args.port
  23         connection = sslcontext.wrap_socket(socket(AF_INET),
  24                                             server_hostname=host)
  25         connection.connect((host, port))
  26
  27     else:
  28         port = 25 if args.port == 0 else args.port
  29
  30         connection = create_connection((host, port))
  31         answer = connection.recv(512)
  32         logging.debug(answer)
  33
  34         connection.send(b"EHLO localhost\r\n")
  35         answer = connection.recv(512)
  36         logging.debug(answer)
  37
  38         connection.send(b"STARTTLS\r\n")
  39         answer = connection.recv(512)
  40         logging.debug(answer)
  41
  42         connection = sslcontext.wrap_socket(connection, server_hostname=host)
  43         connection.do_handshake()
  44
  45     return connection
  46
  47
  48 def close_connection(connection):
  49     connection.send(b"QUIT\r\n")
  50     answer = connection.recv(512)
  51     logging.debug(answer)
  52
  53
  54 def init(args):
  55     sslcontext = SSLContext(PROTOCOL_TLSv1_2)
  56     sslcontext.verify_mode = CERT_REQUIRED
  57     sslcontext.load_verify_locations(args.castore)
  58
  59     resolver = ub_ctx()
  60     resolver.add_ta_file(args.ancor)
  61
  62     return sslcontext, resolver
  63
  64
  65 def main():
  66     logging.basicConfig(format='%(levelname)5s %(message)s')
  67     parser = argparse.ArgumentParser()
  68     parser.add_argument("Host")
  69
  70     parser.add_argument("--verbose", action="store_true")
  71     parser.add_argument("--quiet", action="store_true")
  72     parser.add_argument("-p", "--port",
  73                         action="store", type=int, default=0,
  74                         help="SMTP port")
  75     parser.add_argument("--ssl",
  76                         action="store_true",
  77                         help="Use direct TLS connection instead of starttls (default: disabled)")
  78     parser.add_argument("--check-dane",
  79                         action="store_false",
  80                         help="Verify presented certificate via DANE (default: enabled)")
  81     parser.add_argument("--check-ca",
  82                         action="store_false",
  83                         help="Verify presented certificate via the CA system (default: enabled)")
  84     parser.add_argument("--check-expire",
  85                         action="store_false",
  86                         help="Verify presented certificate for expiration (default: enabled)")
  87
  88     parser.add_argument("-a", "--ancor",
  89                         action="store", type=str, default="/etc/unbound/root.key",
  90                         help="DNSSEC root ancor")
  91     parser.add_argument("--castore", action="store", type=str,
  92                         default="/etc/ssl/certs/ca-certificates.crt",
  93                         help="ca certificate bundle")
  94
  95     group = parser.add_mutually_exclusive_group()
  96     group.add_argument("-6", "--6", action="store_true", help="check via IPv6 only")
  97     group.add_argument("-4", "--4", action="store_true", help="check via IPv4 only")
  98     group.add_argument("--64", action="store_false", help="check via IPv4 and IPv6 (default)")
  99
 100     add_certificate_options(parser)
 101
 102     args = parser.parse_args()
 103
 104     if args.verbose:
 105         logging.getLogger().setLevel(logging.DEBUG)
 106     elif args.quiet:
 107         logging.getLogger().setLevel(logging.WARNING)
 108     else:
 109         logging.getLogger().setLevel(logging.INFO)
 110
 111     port = args.port
 112     if port == 0:
 113         port = 465 if args.ssl else 25
 114     host = args.Host.encode('idna').decode()
 115
 116     sslcontext, resolver = init(args)
 117     try:
 118         connection = init_connection(sslcontext, args)
 119     except ConnectionRefusedError:
 120         logging.error("Connection refused")
 121         return 2
 122
 123     retval = verify_certificate(connection.getpeercert(), args)
 124     nretval = verify_tlsa_record(resolver, "_%d._tcp.%s" % (port, host), connection.getpeercert(binary_form=True))
 125     retval = max(retval, nretval)
 126
 127     close_connection(connection)
 128     return retval
 129
 130
 131 if __name__ == '__main__':
 132     sys.exit(main())