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