ssh-audit/ssh-audit.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
   The MIT License (MIT)
   
   Copyright (C) 2016 Andris Raugulis (moo@arthepsy.eu)
   
   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
   in the Software without restriction, including without limitation the rights
   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   copies of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:
   
   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.
   
   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   THE SOFTWARE.
"""
from __future__ import print_function
import os, io, sys, socket, struct, random, errno, getopt, re, hashlib, base64

VERSION = 'v1.7.1.dev'

if sys.version_info >= (3,):  # pragma: nocover
	StringIO, BytesIO = io.StringIO, io.BytesIO
	text_type = str
	binary_type = bytes
else:  # pragma: nocover
	import StringIO as _StringIO  # pylint: disable=import-error
	StringIO = BytesIO = _StringIO.StringIO
	text_type = unicode  # pylint: disable=undefined-variable
	binary_type = str
try:  # pragma: nocover
	# pylint: disable=unused-import
	from typing import Dict, List, Set, Sequence, Tuple, Iterable
	from typing import Callable, Optional, Union, Any
except ImportError:  # pragma: nocover
	pass
try:  # pragma: nocover
	from colorama import init as colorama_init
	colorama_init()  # pragma: nocover
except ImportError:  # pragma: nocover
	pass


def usage(err=None):
	# type: (Optional[str]) -> None
	uout = Output()
	p = os.path.basename(sys.argv[0])
	uout.head('# {0} {1}, moo@arthepsy.eu\n'.format(p, VERSION))
	if err is not None:
		uout.fail('\n' + err)
	uout.info('usage: {0} [-1246pbnvl] <host>\n'.format(p))
	uout.info('   -h,  --help             print this help')
	uout.info('   -1,  --ssh1             force ssh version 1 only')
	uout.info('   -2,  --ssh2             force ssh version 2 only')
	uout.info('   -4,  --ipv4             enable IPv4 (order of precedence)')
	uout.info('   -6,  --ipv6             enable IPv6 (order of precedence)')
	uout.info('   -p,  --port=<port>      port to connect')
	uout.info('   -b,  --batch            batch output')
	uout.info('   -n,  --no-colors        disable colors')
	uout.info('   -v,  --verbose          verbose output')
	uout.info('   -l,  --level=<level>    minimum output level (info|warn|fail)')
	uout.sep()
	sys.exit(1)


class AuditConf(object):
	# pylint: disable=too-many-instance-attributes
	def __init__(self, host=None, port=22):
		# type: (Optional[str], int) -> None
		self.host = host
		self.port = port
		self.ssh1 = True
		self.ssh2 = True
		self.batch = False
		self.colors = True
		self.verbose = False
		self.minlevel = 'info'
		self.ipvo = ()  # type: Sequence[int]
		self.ipv4 = False
		self.ipv6 = False
	
	def __setattr__(self, name, value):
		# type: (str, Union[str, int, bool, Sequence[int]]) -> None
		valid = False
		if name in ['ssh1', 'ssh2', 'batch', 'colors', 'verbose']:
			valid, value = True, True if value else False
		elif name in ['ipv4', 'ipv6']:
			valid = False
			value = True if value else False
			ipv = 4 if name == 'ipv4' else 6
			if value:
				value = tuple(list(self.ipvo) + [ipv])
			else:
				if len(self.ipvo) == 0:
					value = (6,) if ipv == 4 else (4,)
				else:
					value = tuple(filter(lambda x: x != ipv, self.ipvo))
			self.__setattr__('ipvo', value)
		elif name == 'ipvo':
			if isinstance(value, (tuple, list)):
				uniq_value = utils.unique_seq(value)
				value = tuple(filter(lambda x: x in (4, 6), uniq_value))
				valid = True
				ipv_both = len(value) == 0
				object.__setattr__(self, 'ipv4', ipv_both or 4 in value)
				object.__setattr__(self, 'ipv6', ipv_both or 6 in value)
		elif name == 'port':
			valid, port = True, utils.parse_int(value)
			if port < 1 or port > 65535:
				raise ValueError('invalid port: {0}'.format(value))
			value = port
		elif name in ['minlevel']:
			if value not in ('info', 'warn', 'fail'):
				raise ValueError('invalid level: {0}'.format(value))
			valid = True
		elif name == 'host':
			valid = True
		if valid:
			object.__setattr__(self, name, value)
	
	@classmethod
	def from_cmdline(cls, args, usage_cb):
		# type: (List[str], Callable[..., None]) -> AuditConf
		# pylint: disable=too-many-branches
		aconf = cls()
		try:
			sopts = 'h1246p:bnvl:'
			lopts = ['help', 'ssh1', 'ssh2', 'ipv4', 'ipv6', 'port',
			         'batch', 'no-colors', 'verbose', 'level=']
			opts, args = getopt.getopt(args, sopts, lopts)
		except getopt.GetoptError as err:
			usage_cb(str(err))
		aconf.ssh1, aconf.ssh2 = False, False
		oport = None
		for o, a in opts:
			if o in ('-h', '--help'):
				usage_cb()
			elif o in ('-1', '--ssh1'):
				aconf.ssh1 = True
			elif o in ('-2', '--ssh2'):
				aconf.ssh2 = True
			elif o in ('-4', '--ipv4'):
				aconf.ipv4 = True
			elif o in ('-6', '--ipv6'):
				aconf.ipv6 = True
			elif o in ('-p', '--port'):
				oport = a
			elif o in ('-b', '--batch'):
				aconf.batch = True
				aconf.verbose = True
			elif o in ('-n', '--no-colors'):
				aconf.colors = False
			elif o in ('-v', '--verbose'):
				aconf.verbose = True
			elif o in ('-l', '--level'):
				if a not in ('info', 'warn', 'fail'):
					usage_cb('level {0} is not valid'.format(a))
				aconf.minlevel = a
		if len(args) == 0:
			usage_cb()
		if oport is not None:
			host = args[0]
			port = utils.parse_int(oport)
		else:
			s = args[0].split(':')
			host = s[0].strip()
			if len(s) == 2:
				oport, port = s[1], utils.parse_int(s[1])
			else:
				oport, port = '22', 22
		if not host:
			usage_cb('host is empty')
		if port <= 0 or port > 65535:
			usage_cb('port {0} is not valid'.format(oport))
		aconf.host = host
		aconf.port = port
		if not (aconf.ssh1 or aconf.ssh2):
			aconf.ssh1, aconf.ssh2 = True, True
		return aconf


class Output(object):
	LEVELS = ['info', 'warn', 'fail']
	COLORS = {'head': 36, 'good': 32, 'warn': 33, 'fail': 31}
	
	def __init__(self):
		# type: () -> None
		self.batch = False
		self.colors = True
		self.verbose = False
		self.__minlevel = 0
	
	@property
	def minlevel(self):
		# type: () -> str
		if self.__minlevel < len(self.LEVELS):
			return self.LEVELS[self.__minlevel]
		return 'unknown'
	
	@minlevel.setter
	def minlevel(self, name):
		# type: (str) -> None
		self.__minlevel = self.getlevel(name)
	
	def getlevel(self, name):
		# type: (str) -> int
		cname = 'info' if name == 'good' else name
		if cname not in self.LEVELS:
			return sys.maxsize
		return self.LEVELS.index(cname)
	
	def sep(self):
		# type: () -> None
		if not self.batch:
			print()
	
	@property
	def colors_supported(self):
		# type: () -> bool
		return 'colorama' in sys.modules or os.name == 'posix'
	
	@staticmethod
	def _colorized(color):
		# type: (str) -> Callable[[text_type], None]
		return lambda x: print(u'{0}{1}\033[0m'.format(color, x))
	
	def __getattr__(self, name):
		# type: (str) -> Callable[[text_type], None]
		if name == 'head' and self.batch:
			return lambda x: None
		if not self.getlevel(name) >= self.__minlevel:
			return lambda x: None
		if self.colors and self.colors_supported and name in self.COLORS:
			color = '\033[0;{0}m'.format(self.COLORS[name])
			return self._colorized(color)
		else:
			return lambda x: print(u'{0}'.format(x))


class OutputBuffer(list):
	def __enter__(self):
		# type: () -> OutputBuffer
		# pylint: disable=attribute-defined-outside-init
		self.__buf = StringIO()
		self.__stdout = sys.stdout
		sys.stdout = self.__buf
		return self
	
	def flush(self):
		# type: () -> None
		for line in self:
			print(line)
	
	def __exit__(self, *args):
		# type: (*Any) -> None
		self.extend(self.__buf.getvalue().splitlines())
		sys.stdout = self.__stdout


class SSH2(object):  # pylint: disable=too-few-public-methods
	class KexDB(object):  # pylint: disable=too-few-public-methods
		# pylint: disable=bad-whitespace
		WARN_OPENSSH74_UNSAFE = 'disabled (in client) since OpenSSH 7.4, unsafe algorithm'
		WARN_OPENSSH72_LEGACY = 'disabled (in client) since OpenSSH 7.2, legacy algorithm'
		FAIL_OPENSSH70_LEGACY = 'removed since OpenSSH 7.0, legacy algorithm'
		FAIL_OPENSSH70_WEAK   = 'removed (in server) and disabled (in client) since OpenSSH 7.0, weak algorithm'
		FAIL_OPENSSH70_LOGJAM = 'disabled (in client) since OpenSSH 7.0, logjam attack'
		INFO_OPENSSH69_CHACHA = 'default cipher since OpenSSH 6.9.'
		FAIL_OPENSSH67_UNSAFE = 'removed (in server) since OpenSSH 6.7, unsafe algorithm'
		FAIL_OPENSSH61_REMOVE = 'removed since OpenSSH 6.1, removed from specification'
		FAIL_OPENSSH31_REMOVE = 'removed since OpenSSH 3.1'
		FAIL_DBEAR67_DISABLED = 'disabled since Dropbear SSH 2015.67'
		FAIL_DBEAR53_DISABLED = 'disabled since Dropbear SSH 0.53'
		FAIL_PLAINTEXT        = 'no encryption/integrity'
		WARN_CURVES_WEAK      = 'using weak elliptic curves'
		WARN_RNDSIG_KEY       = 'using weak random number generator could reveal the key'
		WARN_MODULUS_SIZE     = 'using small 1024-bit modulus'
		WARN_MODULUS_CUSTOM   = 'using custom size modulus (possibly weak)'
		WARN_HASH_WEAK        = 'using weak hashing algorithm'
		WARN_CIPHER_MODE      = 'using weak cipher mode'
		WARN_BLOCK_SIZE       = 'using small 64-bit block size'
		WARN_CIPHER_WEAK      = 'using weak cipher'
		WARN_ENCRYPT_AND_MAC  = 'using encrypt-and-MAC mode'
		WARN_TAG_SIZE         = 'using small 64-bit tag size'
		
		ALGORITHMS = {
			'kex': {
				'diffie-hellman-group1-sha1': [['2.3.0,d0.28,l10.2', '6.6', '6.9'], [FAIL_OPENSSH67_UNSAFE, FAIL_OPENSSH70_LOGJAM], [WARN_MODULUS_SIZE, WARN_HASH_WEAK]],
				'diffie-hellman-group14-sha1': [['3.9,d0.53,l10.6.0'], [], [WARN_HASH_WEAK]],
				'diffie-hellman-group14-sha256': [['7.3,d2016.73']],
				'diffie-hellman-group16-sha512': [['7.3,d2016.73']],
				'diffie-hellman-group18-sha512': [['7.3']],
				'diffie-hellman-group-exchange-sha1': [['2.3.0', '6.6', None], [FAIL_OPENSSH67_UNSAFE], [WARN_HASH_WEAK]],
				'diffie-hellman-group-exchange-sha256': [['4.4'], [], [WARN_MODULUS_CUSTOM]],
				'ecdh-sha2-nistp256': [['5.7,d2013.62,l10.6.0'], [WARN_CURVES_WEAK]],
				'ecdh-sha2-nistp384': [['5.7,d2013.62'], [WARN_CURVES_WEAK]],
				'ecdh-sha2-nistp521': [['5.7,d2013.62'], [WARN_CURVES_WEAK]],
				'curve25519-sha256@libssh.org': [['6.5,d2013.62,l10.6.0']],
				'curve25519-sha256': [['7.4']],
				'kexguess2@matt.ucc.asn.au': [['d2013.57']],
			},
			'key': {
				'rsa-sha2-256': [['7.2']],
				'rsa-sha2-512': [['7.2']],
				'ssh-ed25519': [['6.5,l10.7.0']],
				'ssh-ed25519-cert-v01@openssh.com': [['6.5']],
				'ssh-rsa': [['2.5.0,d0.28,l10.2']],
				'ssh-dss': [['2.1.0,d0.28,l10.2', '6.9'], [FAIL_OPENSSH70_WEAK], [WARN_MODULUS_SIZE, WARN_RNDSIG_KEY]],
				'ecdsa-sha2-nistp256': [['5.7,d2013.62,l10.6.4'], [WARN_CURVES_WEAK], [WARN_RNDSIG_KEY]],
				'ecdsa-sha2-nistp384': [['5.7,d2013.62,l10.6.4'], [WARN_CURVES_WEAK], [WARN_RNDSIG_KEY]],
				'ecdsa-sha2-nistp521': [['5.7,d2013.62,l10.6.4'], [WARN_CURVES_WEAK], [WARN_RNDSIG_KEY]],
				'ssh-rsa-cert-v00@openssh.com': [['5.4', '6.9'], [FAIL_OPENSSH70_LEGACY], []],
				'ssh-dss-cert-v00@openssh.com': [['5.4', '6.9'], [FAIL_OPENSSH70_LEGACY], [WARN_MODULUS_SIZE, WARN_RNDSIG_KEY]],
				'ssh-rsa-cert-v01@openssh.com': [['5.6']],
				'ssh-dss-cert-v01@openssh.com': [['5.6', '6.9'], [FAIL_OPENSSH70_WEAK], [WARN_MODULUS_SIZE, WARN_RNDSIG_KEY]],
				'ecdsa-sha2-nistp256-cert-v01@openssh.com': [['5.7'], [WARN_CURVES_WEAK], [WARN_RNDSIG_KEY]],
				'ecdsa-sha2-nistp384-cert-v01@openssh.com': [['5.7'], [WARN_CURVES_WEAK], [WARN_RNDSIG_KEY]],
				'ecdsa-sha2-nistp521-cert-v01@openssh.com': [['5.7'], [WARN_CURVES_WEAK], [WARN_RNDSIG_KEY]],
			},
			'enc': {
				'none': [['1.2.2,d2013.56,l10.2'], [FAIL_PLAINTEXT]],
				'3des-cbc': [['1.2.2,d0.28,l10.2', '6.6', None], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH74_UNSAFE, WARN_CIPHER_WEAK, WARN_CIPHER_MODE, WARN_BLOCK_SIZE]],
				'3des-ctr': [['d0.52']],
				'blowfish-cbc': [['1.2.2,d0.28,l10.2', '6.6,d0.52', '7.1,d0.52'], [FAIL_OPENSSH67_UNSAFE, FAIL_DBEAR53_DISABLED], [WARN_OPENSSH72_LEGACY, WARN_CIPHER_MODE, WARN_BLOCK_SIZE]],
				'twofish-cbc': [['d0.28', 'd2014.66'], [FAIL_DBEAR67_DISABLED], [WARN_CIPHER_MODE]],
				'twofish128-cbc': [['d0.47', 'd2014.66'], [FAIL_DBEAR67_DISABLED], [WARN_CIPHER_MODE]],
				'twofish256-cbc': [['d0.47', 'd2014.66'], [FAIL_DBEAR67_DISABLED], [WARN_CIPHER_MODE]],
				'twofish128-ctr': [['d2015.68']],
				'twofish256-ctr': [['d2015.68']],
				'cast128-cbc': [['2.1.0', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_CIPHER_MODE, WARN_BLOCK_SIZE]],
				'arcfour': [['2.1.0', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_CIPHER_WEAK]],
				'arcfour128': [['4.2', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_CIPHER_WEAK]],
				'arcfour256': [['4.2', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_CIPHER_WEAK]],
				'aes128-cbc': [['2.3.0,d0.28,l10.2', '6.6', None], [FAIL_OPENSSH67_UNSAFE], [WARN_CIPHER_MODE]],
				'aes192-cbc': [['2.3.0,l10.2', '6.6', None], [FAIL_OPENSSH67_UNSAFE], [WARN_CIPHER_MODE]],
				'aes256-cbc': [['2.3.0,d0.47,l10.2', '6.6', None], [FAIL_OPENSSH67_UNSAFE], [WARN_CIPHER_MODE]],
				'rijndael128-cbc': [['2.3.0', '3.0.2'], [FAIL_OPENSSH31_REMOVE], [WARN_CIPHER_MODE]],
				'rijndael192-cbc': [['2.3.0', '3.0.2'], [FAIL_OPENSSH31_REMOVE], [WARN_CIPHER_MODE]],
				'rijndael256-cbc': [['2.3.0', '3.0.2'], [FAIL_OPENSSH31_REMOVE], [WARN_CIPHER_MODE]],
				'rijndael-cbc@lysator.liu.se': [['2.3.0', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_CIPHER_MODE]],
				'aes128-ctr': [['3.7,d0.52,l10.4.1']],
				'aes192-ctr': [['3.7,l10.4.1']],
				'aes256-ctr': [['3.7,d0.52,l10.4.1']],
				'aes128-gcm@openssh.com': [['6.2']],
				'aes256-gcm@openssh.com': [['6.2']],
				'chacha20-poly1305@openssh.com': [['6.5'], [], [], [INFO_OPENSSH69_CHACHA]],
			},
			'mac': {
				'none': [['d2013.56'], [FAIL_PLAINTEXT]],
				'hmac-sha1': [['2.1.0,d0.28,l10.2'], [], [WARN_ENCRYPT_AND_MAC, WARN_HASH_WEAK]],
				'hmac-sha1-96': [['2.5.0,d0.47', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_ENCRYPT_AND_MAC, WARN_HASH_WEAK]],
				'hmac-sha2-256': [['5.9,d2013.56,l10.7.0'], [], [WARN_ENCRYPT_AND_MAC]],
				'hmac-sha2-256-96': [['5.9', '6.0'], [FAIL_OPENSSH61_REMOVE], [WARN_ENCRYPT_AND_MAC]],
				'hmac-sha2-512': [['5.9,d2013.56,l10.7.0'], [], [WARN_ENCRYPT_AND_MAC]],
				'hmac-sha2-512-96': [['5.9', '6.0'], [FAIL_OPENSSH61_REMOVE], [WARN_ENCRYPT_AND_MAC]],
				'hmac-md5': [['2.1.0,d0.28', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_ENCRYPT_AND_MAC, WARN_HASH_WEAK]],
				'hmac-md5-96': [['2.5.0', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_ENCRYPT_AND_MAC, WARN_HASH_WEAK]],
				'hmac-ripemd160': [['2.5.0', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_ENCRYPT_AND_MAC]],
				'hmac-ripemd160@openssh.com': [['2.1.0', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_ENCRYPT_AND_MAC]],
				'umac-64@openssh.com': [['4.7'], [], [WARN_ENCRYPT_AND_MAC, WARN_TAG_SIZE]],
				'umac-128@openssh.com': [['6.2'], [], [WARN_ENCRYPT_AND_MAC]],
				'hmac-sha1-etm@openssh.com': [['6.2'], [], [WARN_HASH_WEAK]],
				'hmac-sha1-96-etm@openssh.com': [['6.2', '6.6', None], [FAIL_OPENSSH67_UNSAFE], [WARN_HASH_WEAK]],
				'hmac-sha2-256-etm@openssh.com': [['6.2']],
				'hmac-sha2-512-etm@openssh.com': [['6.2']],
				'hmac-md5-etm@openssh.com': [['6.2', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_HASH_WEAK]],
				'hmac-md5-96-etm@openssh.com': [['6.2', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY, WARN_HASH_WEAK]],
				'hmac-ripemd160-etm@openssh.com': [['6.2', '6.6', '7.1'], [FAIL_OPENSSH67_UNSAFE], [WARN_OPENSSH72_LEGACY]],
				'umac-64-etm@openssh.com': [['6.2'], [], [WARN_TAG_SIZE]],
				'umac-128-etm@openssh.com': [['6.2']],
			}
		}  # type: Dict[str, Dict[str, List[List[Optional[str]]]]]
	
	class KexParty(object):
		def __init__(self, enc, mac, compression, languages):
			# type: (List[text_type], List[text_type], List[text_type], List[text_type]) -> None
			self.__enc = enc
			self.__mac = mac
			self.__compression = compression
			self.__languages = languages
		
		@property
		def encryption(self):
			# type: () -> List[text_type]
			return self.__enc
		
		@property
		def mac(self):
			# type: () -> List[text_type]
			return self.__mac
		
		@property
		def compression(self):
			# type: () -> List[text_type]
			return self.__compression
		
		@property
		def languages(self):
			# type: () -> List[text_type]
			return self.__languages
	
	class Kex(object):
		def __init__(self, cookie, kex_algs, key_algs, cli, srv, follows, unused=0):
			# type: (binary_type, List[text_type], List[text_type], SSH2.KexParty, SSH2.KexParty, bool, int) -> None
			self.__cookie = cookie
			self.__kex_algs = kex_algs
			self.__key_algs = key_algs
			self.__client = cli
			self.__server = srv
			self.__follows = follows
			self.__unused = unused
		
		@property
		def cookie(self):
			# type: () -> binary_type
			return self.__cookie
		
		@property
		def kex_algorithms(self):
			# type: () -> List[text_type]
			return self.__kex_algs
		
		@property
		def key_algorithms(self):
			# type: () -> List[text_type]
			return self.__key_algs
		
		# client_to_server
		@property
		def client(self):
			# type: () -> SSH2.KexParty
			return self.__client
		
		# server_to_client
		@property
		def server(self):
			# type: () -> SSH2.KexParty
			return self.__server
		
		@property
		def follows(self):
			# type: () -> bool
			return self.__follows
		
		@property
		def unused(self):
			# type: () -> int
			return self.__unused
		
		def write(self, wbuf):
			# type: (WriteBuf) -> None
			wbuf.write(self.cookie)
			wbuf.write_list(self.kex_algorithms)
			wbuf.write_list(self.key_algorithms)
			wbuf.write_list(self.client.encryption)
			wbuf.write_list(self.server.encryption)
			wbuf.write_list(self.client.mac)
			wbuf.write_list(self.server.mac)
			wbuf.write_list(self.client.compression)
			wbuf.write_list(self.server.compression)
			wbuf.write_list(self.client.languages)
			wbuf.write_list(self.server.languages)
			wbuf.write_bool(self.follows)
			wbuf.write_int(self.__unused)
		
		@property
		def payload(self):
			# type: () -> binary_type
			wbuf = WriteBuf()
			self.write(wbuf)
			return wbuf.write_flush()
		
		@classmethod
		def parse(cls, payload):
			# type: (binary_type) -> SSH2.Kex
			buf = ReadBuf(payload)
			cookie = buf.read(16)
			kex_algs = buf.read_list()
			key_algs = buf.read_list()
			cli_enc = buf.read_list()
			srv_enc = buf.read_list()
			cli_mac = buf.read_list()
			srv_mac = buf.read_list()
			cli_compression = buf.read_list()
			srv_compression = buf.read_list()
			cli_languages = buf.read_list()
			srv_languages = buf.read_list()
			follows = buf.read_bool()
			unused = buf.read_int()
			cli = SSH2.KexParty(cli_enc, cli_mac, cli_compression, cli_languages)
			srv = SSH2.KexParty(srv_enc, srv_mac, srv_compression, srv_languages)
			kex = cls(cookie, kex_algs, key_algs, cli, srv, follows, unused)
			return kex


class SSH1(object):
	class CRC32(object):
		def __init__(self):
			# type: () -> None
			self._table = [0] * 256
			for i in range(256):
				crc = 0
				n = i
				for _ in range(8):
					x = (crc ^ n) & 1
					crc = (crc >> 1) ^ (x * 0xedb88320)
					n = n >> 1
				self._table[i] = crc
		
		def calc(self, v):
			# type: (binary_type) -> int
			crc, l = 0, len(v)
			for i in range(l):
				n = ord(v[i:i + 1])
				n = n ^ (crc & 0xff)
				crc = (crc >> 8) ^ self._table[n]
			return crc
	
	_crc32 = None  # type: Optional[SSH1.CRC32]
	CIPHERS = ['none', 'idea', 'des', '3des', 'tss', 'rc4', 'blowfish']
	AUTHS = ['none', 'rhosts', 'rsa', 'password', 'rhosts_rsa', 'tis', 'kerberos']
	
	@classmethod
	def crc32(cls, v):
		# type: (binary_type) -> int
		if cls._crc32 is None:
			cls._crc32 = cls.CRC32()
		return cls._crc32.calc(v)
	
	class KexDB(object):  # pylint: disable=too-few-public-methods
		# pylint: disable=bad-whitespace
		FAIL_PLAINTEXT        = 'no encryption/integrity'
		FAIL_OPENSSH37_REMOVE = 'removed since OpenSSH 3.7'
		FAIL_NA_BROKEN        = 'not implemented in OpenSSH, broken algorithm'
		FAIL_NA_UNSAFE        = 'not implemented in OpenSSH (server), unsafe algorithm'
		TEXT_CIPHER_IDEA      = 'cipher used by commercial SSH'
		
		ALGORITHMS = {
			'key': {
				'ssh-rsa1': [['1.2.2']],
			},
			'enc': {
				'none': [['1.2.2'], [FAIL_PLAINTEXT]],
				'idea': [[None], [], [], [TEXT_CIPHER_IDEA]],
				'des': [['2.3.0C'], [FAIL_NA_UNSAFE]],
				'3des': [['1.2.2']],
				'tss': [[''], [FAIL_NA_BROKEN]],
				'rc4': [[], [FAIL_NA_BROKEN]],
				'blowfish': [['1.2.2']],
			},
			'aut': {
				'rhosts': [['1.2.2', '3.6'], [FAIL_OPENSSH37_REMOVE]],
				'rsa': [['1.2.2']],
				'password': [['1.2.2']],
				'rhosts_rsa': [['1.2.2']],
				'tis': [['1.2.2']],
				'kerberos': [['1.2.2', '3.6'], [FAIL_OPENSSH37_REMOVE]],
			}
		}  # type: Dict[str, Dict[str, List[List[Optional[str]]]]]
	
	class PublicKeyMessage(object):
		def __init__(self, cookie, skey, hkey, pflags, cmask, amask):
			# type: (binary_type, Tuple[int, int, int], Tuple[int, int, int], int, int, int) -> None
			assert len(skey) == 3
			assert len(hkey) == 3
			self.__cookie = cookie
			self.__server_key = skey
			self.__host_key = hkey
			self.__protocol_flags = pflags
			self.__supported_ciphers_mask = cmask
			self.__supported_authentications_mask = amask
		
		@property
		def cookie(self):
			# type: () -> binary_type
			return self.__cookie
		
		@property
		def server_key_bits(self):
			# type: () -> int
			return self.__server_key[0]
		
		@property
		def server_key_public_exponent(self):
			# type: () -> int
			return self.__server_key[1]
		
		@property
		def server_key_public_modulus(self):
			# type: () -> int
			return self.__server_key[2]
		
		@property
		def host_key_bits(self):
			# type: () -> int
			return self.__host_key[0]
		
		@property
		def host_key_public_exponent(self):
			# type: () -> int
			return self.__host_key[1]
		
		@property
		def host_key_public_modulus(self):
			# type: () -> int
			return self.__host_key[2]
		
		@property
		def host_key_fingerprint_data(self):
			# type: () -> binary_type
			# pylint: disable=protected-access
			mod = WriteBuf._create_mpint(self.host_key_public_modulus, False)
			e = WriteBuf._create_mpint(self.host_key_public_exponent, False)
			return mod + e
		
		@property
		def protocol_flags(self):
			# type: () -> int
			return self.__protocol_flags
		
		@property
		def supported_ciphers_mask(self):
			# type: () -> int
			return self.__supported_ciphers_mask
		
		@property
		def supported_ciphers(self):
			# type: () -> List[text_type]
			ciphers = []
			for i in range(len(SSH1.CIPHERS)):
				if self.__supported_ciphers_mask & (1 << i) != 0:
					ciphers.append(utils.to_utext(SSH1.CIPHERS[i]))
			return ciphers
		
		@property
		def supported_authentications_mask(self):
			# type: () -> int
			return self.__supported_authentications_mask
		
		@property
		def supported_authentications(self):
			# type: () -> List[text_type]
			auths = []
			for i in range(1, len(SSH1.AUTHS)):
				if self.__supported_authentications_mask & (1 << i) != 0:
					auths.append(utils.to_utext(SSH1.AUTHS[i]))
			return auths
		
		def write(self, wbuf):
			# type: (WriteBuf) -> None
			wbuf.write(self.cookie)
			wbuf.write_int(self.server_key_bits)
			wbuf.write_mpint1(self.server_key_public_exponent)
			wbuf.write_mpint1(self.server_key_public_modulus)
			wbuf.write_int(self.host_key_bits)
			wbuf.write_mpint1(self.host_key_public_exponent)
			wbuf.write_mpint1(self.host_key_public_modulus)
			wbuf.write_int(self.protocol_flags)
			wbuf.write_int(self.supported_ciphers_mask)
			wbuf.write_int(self.supported_authentications_mask)
		
		@property
		def payload(self):
			# type: () -> binary_type
			wbuf = WriteBuf()
			self.write(wbuf)
			return wbuf.write_flush()
		
		@classmethod
		def parse(cls, payload):
			# type: (binary_type) -> SSH1.PublicKeyMessage
			buf = ReadBuf(payload)
			cookie = buf.read(8)
			server_key_bits = buf.read_int()
			server_key_exponent = buf.read_mpint1()
			server_key_modulus = buf.read_mpint1()
			skey = (server_key_bits, server_key_exponent, server_key_modulus)
			host_key_bits = buf.read_int()
			host_key_exponent = buf.read_mpint1()
			host_key_modulus = buf.read_mpint1()
			hkey = (host_key_bits, host_key_exponent, host_key_modulus)
			pflags = buf.read_int()
			cmask = buf.read_int()
			amask = buf.read_int()
			pkm = cls(cookie, skey, hkey, pflags, cmask, amask)
			return pkm


class ReadBuf(object):
	def __init__(self, data=None):
		# type: (Optional[binary_type]) -> None
		super(ReadBuf, self).__init__()
		self._buf = BytesIO(data) if data else BytesIO()
		self._len = len(data) if data else 0
	
	@property
	def unread_len(self):
		# type: () -> int
		return self._len - self._buf.tell()
	
	def read(self, size):
		# type: (int) -> binary_type
		return self._buf.read(size)
	
	def read_byte(self):
		# type: () -> int
		v = struct.unpack('B', self.read(1))[0]  # type: int
		return v
	
	def read_bool(self):
		# type: () -> bool
		return self.read_byte() != 0
	
	def read_int(self):
		# type: () -> int
		v = struct.unpack('>I', self.read(4))[0]  # type: int
		return v
	
	def read_list(self):
		# type: () -> List[text_type]
		list_size = self.read_int()
		return self.read(list_size).decode('utf-8', 'replace').split(',')
	
	def read_string(self):
		# type: () -> binary_type
		n = self.read_int()
		return self.read(n)
	
	@classmethod
	def _parse_mpint(cls, v, pad, sf):
		# type: (binary_type, binary_type, str) -> int
		r = 0
		if len(v) % 4:
			v = pad * (4 - (len(v) % 4)) + v
		for i in range(0, len(v), 4):
			r = (r << 32) | struct.unpack(sf, v[i:i + 4])[0]
		return r
		
	def read_mpint1(self):
		# type: () -> int
		# NOTE: Data Type Enc @ http://www.snailbook.com/docs/protocol-1.5.txt
		bits = struct.unpack('>H', self.read(2))[0]
		n = (bits + 7) // 8
		return self._parse_mpint(self.read(n), b'\x00', '>I')
	
	def read_mpint2(self):
		# type: () -> int
		# NOTE: Section 5 @ https://www.ietf.org/rfc/rfc4251.txt
		v = self.read_string()
		if len(v) == 0:
			return 0
		pad, sf = (b'\xff', '>i') if ord(v[0:1]) & 0x80 else (b'\x00', '>I')
		return self._parse_mpint(v, pad, sf)
	
	def read_line(self):
		# type: () -> text_type
		return self._buf.readline().rstrip().decode('utf-8', 'replace')


class WriteBuf(object):
	def __init__(self, data=None):
		# type: (Optional[binary_type]) -> None
		super(WriteBuf, self).__init__()
		self._wbuf = BytesIO(data) if data else BytesIO()
	
	def write(self, data):
		# type: (binary_type) -> WriteBuf
		self._wbuf.write(data)
		return self
	
	def write_byte(self, v):
		# type: (int) -> WriteBuf
		return self.write(struct.pack('B', v))
	
	def write_bool(self, v):
		# type: (bool) -> WriteBuf
		return self.write_byte(1 if v else 0)
	
	def write_int(self, v):
		# type: (int) -> WriteBuf
		return self.write(struct.pack('>I', v))
	
	def write_string(self, v):
		# type: (Union[binary_type, text_type]) -> WriteBuf
		if not isinstance(v, bytes):
			v = bytes(bytearray(v, 'utf-8'))
		self.write_int(len(v))
		return self.write(v)
	
	def write_list(self, v):
		# type: (List[text_type]) -> WriteBuf
		return self.write_string(u','.join(v))
	
	@classmethod
	def _bitlength(cls, n):
		# type: (int) -> int
		try:
			return n.bit_length()
		except AttributeError:
			return len(bin(n)) - (2 if n > 0 else 3)
		
	@classmethod
	def _create_mpint(cls, n, signed=True, bits=None):
		# type: (int, bool, Optional[int]) -> binary_type
		if bits is None:
			bits = cls._bitlength(n)
		length = bits // 8 + (1 if n != 0 else 0)
		ql = (length + 7) // 8
		fmt, v2 = '>{0}Q'.format(ql), [0] * ql
		for i in range(ql):
			v2[ql - i - 1] = (n & 0xffffffffffffffff)
			n >>= 64
		data = bytes(struct.pack(fmt, *v2)[-length:])
		if not signed:
			data = data.lstrip(b'\x00')
		elif data.startswith(b'\xff\x80'):
			data = data[1:]
		return data
	
	def write_mpint1(self, n):
		# type: (int) -> WriteBuf
		# NOTE: Data Type Enc @ http://www.snailbook.com/docs/protocol-1.5.txt
		bits = self._bitlength(n)
		data = self._create_mpint(n, False, bits)
		self.write(struct.pack('>H', bits))
		return self.write(data)
	
	def write_mpint2(self, n):
		# type: (int) -> WriteBuf
		# NOTE: Section 5 @ https://www.ietf.org/rfc/rfc4251.txt
		data = self._create_mpint(n)
		return self.write_string(data)
	
	def write_line(self, v):
		# type: (Union[binary_type, str]) -> WriteBuf
		if not isinstance(v, bytes):
			v = bytes(bytearray(v, 'utf-8'))
		v += b'\r\n'
		return self.write(v)
	
	def write_flush(self):
		# type: () -> binary_type
		payload = self._wbuf.getvalue()
		self._wbuf.truncate(0)
		self._wbuf.seek(0)
		return payload


class SSH(object):  # pylint: disable=too-few-public-methods
	class Protocol(object):  # pylint: disable=too-few-public-methods
		# pylint: disable=bad-whitespace
		SMSG_PUBLIC_KEY = 2
		MSG_KEXINIT     = 20
		MSG_NEWKEYS     = 21
		MSG_KEXDH_INIT  = 30
		MSG_KEXDH_REPLY = 32
	
	class Product(object):  # pylint: disable=too-few-public-methods
		OpenSSH = 'OpenSSH'
		DropbearSSH = 'Dropbear SSH'
		LibSSH = 'libssh'
	
	class Software(object):
		def __init__(self, vendor, product, version, patch, os_version):
			# type: (Optional[str], str, str, Optional[str], Optional[str]) -> None
			self.__vendor = vendor
			self.__product = product
			self.__version = version
			self.__patch = patch
			self.__os = os_version
		
		@property
		def vendor(self):
			# type: () -> Optional[str]
			return self.__vendor
		
		@property
		def product(self):
			# type: () -> str
			return self.__product
		
		@property
		def version(self):
			# type: () -> str
			return self.__version
		
		@property
		def patch(self):
			# type: () -> Optional[str]
			return self.__patch
		
		@property
		def os(self):
			# type: () -> Optional[str]
			return self.__os
		
		def compare_version(self, other):
			# type: (Union[None, SSH.Software, text_type]) -> int
			# pylint: disable=too-many-branches
			if other is None:
				return 1
			if isinstance(other, SSH.Software):
				other = '{0}{1}'.format(other.version, other.patch or '')
			else:
				other = str(other)
			mx = re.match(r'^([\d\.]+\d+)(.*)$', other)
			if mx:
				oversion, opatch = mx.group(1), mx.group(2).strip()
			else:
				oversion, opatch = other, ''
			if self.version < oversion:
				return -1
			elif self.version > oversion:
				return 1
			spatch = self.patch or ''
			if self.product == SSH.Product.DropbearSSH:
				if not re.match(r'^test\d.*$', opatch):
					opatch = 'z{0}'.format(opatch)
				if not re.match(r'^test\d.*$', spatch):
					spatch = 'z{0}'.format(spatch)
			elif self.product == SSH.Product.OpenSSH:
				mx1 = re.match(r'^p\d(.*)', opatch)
				mx2 = re.match(r'^p\d(.*)', spatch)
				if not (mx1 and mx2):
					if mx1:
						opatch = mx1.group(1)
					if mx2:
						spatch = mx2.group(1)
			if spatch < opatch:
				return -1
			elif spatch > opatch:
				return 1
			return 0
		
		def between_versions(self, vfrom, vtill):
			# type: (str, str) -> bool
			if vfrom and self.compare_version(vfrom) < 0:
				return False
			if vtill and self.compare_version(vtill) > 0:
				return False
			return True
		
		def display(self, full=True):
			# type: (bool) -> str
			r = '{0} '.format(self.vendor) if self.vendor else ''
			r += self.product
			if self.version:
				r += ' {0}'.format(self.version)
			if full:
				patch = self.patch or ''
				if self.product == SSH.Product.OpenSSH:
					mx = re.match(r'^(p\d)(.*)$', patch)
					if mx is not None:
						r += mx.group(1)
						patch = mx.group(2).strip()
				if patch:
					r += ' ({0})'.format(patch)
				if self.os:
					r += ' running on {0}'.format(self.os)
			return r
		
		def __str__(self):
			# type: () -> str
			return self.display()
		
		def __repr__(self):
			# type: () -> str
			r = 'vendor={0}'.format(self.vendor) if self.vendor else ''
			if self.product:
				if self.vendor:
					r += ', '
				r += 'product={0}'.format(self.product)
			if self.version:
				r += ', version={0}'.format(self.version)
			if self.patch:
				r += ', patch={0}'.format(self.patch)
			if self.os:
				r += ', os={0}'.format(self.os)
			return '<{0}({1})>'.format(self.__class__.__name__, r)
		
		@staticmethod
		def _fix_patch(patch):
			# type: (str) -> Optional[str]
			return re.sub(r'^[-_\.]+', '', patch) or None
		
		@staticmethod
		def _fix_date(d):
			# type: (str) -> Optional[str]
			if d is not None and len(d) == 8:
				return '{0}-{1}-{2}'.format(d[:4], d[4:6], d[6:8])
			else:
				return None
		
		@classmethod
		def _extract_os_version(cls, c):
			# type: (Optional[str]) -> Optional[str]
			if c is None:
				return None
			mx = re.match(r'^NetBSD(?:_Secure_Shell)?(?:[\s-]+(\d{8})(.*))?$', c)
			if mx:
				d = cls._fix_date(mx.group(1))
				return 'NetBSD' if d is None else 'NetBSD ({0})'.format(d)
			mx = re.match(r'^FreeBSD(?:\slocalisations)?[\s-]+(\d{8})(.*)$', c)
			if not mx:
				mx = re.match(r'^[^@]+@FreeBSD\.org[\s-]+(\d{8})(.*)$', c)
			if mx:
				d = cls._fix_date(mx.group(1))
				return 'FreeBSD' if d is None else 'FreeBSD ({0})'.format(d)
			w = ['RemotelyAnywhere', 'DesktopAuthority', 'RemoteSupportManager']
			for win_soft in w:
				mx = re.match(r'^in ' + win_soft + r' ([\d\.]+\d)$', c)
				if mx:
					ver = mx.group(1)
					return 'Microsoft Windows ({0} {1})'.format(win_soft, ver)
			generic = ['NetBSD', 'FreeBSD']
			for g in generic:
				if c.startswith(g) or c.endswith(g):
					return g
			return None
		
		@classmethod
		def parse(cls, banner):
			# type: (SSH.Banner) -> Optional[SSH.Software]
			# pylint: disable=too-many-return-statements
			software = str(banner.software)
			mx = re.match(r'^dropbear_([\d\.]+\d+)(.*)', software)
			v = None  # type: Optional[str]
			if mx:
				patch = cls._fix_patch(mx.group(2))
				v, p = 'Matt Johnston', SSH.Product.DropbearSSH
				v = None
				return cls(v, p, mx.group(1), patch, None)
			mx = re.match(r'^OpenSSH[_\.-]+([\d\.]+\d+)(.*)', software)
			if mx:
				patch = cls._fix_patch(mx.group(2))
				v, p = 'OpenBSD', SSH.Product.OpenSSH
				v = None
				os_version = cls._extract_os_version(banner.comments)
				return cls(v, p, mx.group(1), patch, os_version)
			mx = re.match(r'^libssh-([\d\.]+\d+)(.*)', software)
			if mx:
				patch = cls._fix_patch(mx.group(2))
				v, p = None, SSH.Product.LibSSH
				os_version = cls._extract_os_version(banner.comments)
				return cls(v, p, mx.group(1), patch, os_version)
			mx = re.match(r'^RomSShell_([\d\.]+\d+)(.*)', software)
			if mx:
				patch = cls._fix_patch(mx.group(2))
				v, p = 'Allegro Software', 'RomSShell'
				return cls(v, p, mx.group(1), patch, None)
			mx = re.match(r'^mpSSH_([\d\.]+\d+)', software)
			if mx:
				v, p = 'HP', 'iLO (Integrated Lights-Out) sshd'
				return cls(v, p, mx.group(1), None, None)
			mx = re.match(r'^Cisco-([\d\.]+\d+)', software)
			if mx:
				v, p = 'Cisco', 'IOS/PIX sshd'
				return cls(v, p, mx.group(1), None, None)
			return None
	
	class Banner(object):
		_RXP, _RXR = r'SSH-\d\.\s*?\d+', r'(-\s*([^\s]*)(?:\s+(.*))?)?'
		RX_PROTOCOL = re.compile(re.sub(r'\\d(\+?)', r'(\\d\g<1>)', _RXP))
		RX_BANNER = re.compile(r'^({0}(?:(?:-{0})*)){1}$'.format(_RXP, _RXR))
		
		def __init__(self, protocol, software, comments, valid_ascii):
			# type: (Tuple[int, int], Optional[str], Optional[str], bool) -> None
			self.__protocol = protocol
			self.__software = software
			self.__comments = comments
			self.__valid_ascii = valid_ascii
		
		@property
		def protocol(self):
			# type: () -> Tuple[int, int]
			return self.__protocol
		
		@property
		def software(self):
			# type: () -> Optional[str]
			return self.__software
		
		@property
		def comments(self):
			# type: () -> Optional[str]
			return self.__comments
		
		@property
		def valid_ascii(self):
			# type: () -> bool
			return self.__valid_ascii
		
		def __str__(self):
			# type: () -> str
			r = 'SSH-{0}.{1}'.format(self.protocol[0], self.protocol[1])
			if self.software is not None:
				r += '-{0}'.format(self.software)
			if self.comments:
				r += ' {0}'.format(self.comments)
			return r
		
		def __repr__(self):
			# type: () -> str
			p = '{0}.{1}'.format(self.protocol[0], self.protocol[1])
			r = 'protocol={0}'.format(p)
			if self.software:
				r += ', software={0}'.format(self.software)
			if self.comments:
				r += ', comments={0}'.format(self.comments)
			return '<{0}({1})>'.format(self.__class__.__name__, r)
		
		@classmethod
		def parse(cls, banner):
			# type: (text_type) -> SSH.Banner
			valid_ascii = utils.is_print_ascii(banner)
			ascii_banner = utils.to_print_ascii(banner)
			mx = cls.RX_BANNER.match(ascii_banner)
			if mx is None:
				return None
			protocol = min(re.findall(cls.RX_PROTOCOL, mx.group(1)))
			protocol = (int(protocol[0]), int(protocol[1]))
			software = (mx.group(3) or '').strip() or None
			if software is None and (mx.group(2) or '').startswith('-'):
				software = ''
			comments = (mx.group(4) or '').strip() or None
			if comments is not None:
				comments = re.sub(r'\s+', ' ', comments)
			return cls(protocol, software, comments, valid_ascii)
	
	class Fingerprint(object):
		def __init__(self, fpd):
			# type: (binary_type) -> None
			self.__fpd = fpd
		
		@property
		def md5(self):
			# type: () -> text_type
			h = hashlib.md5(self.__fpd).hexdigest()
			r = u':'.join(h[i:i + 2] for i in range(0, len(h), 2))
			return u'MD5:{0}'.format(r)
		
		@property
		def sha256(self):
			# type: () -> text_type
			h = base64.b64encode(hashlib.sha256(self.__fpd).digest())
			r = h.decode('ascii').rstrip('=')
			return u'SHA256:{0}'.format(r)
	
	class Algorithm(object):
		@staticmethod
		def get_ssh_version(version_desc):
			# type: (str) -> Tuple[str, str]
			if version_desc.startswith('d'):
				return (SSH.Product.DropbearSSH, version_desc[1:])
			elif version_desc.startswith('l1'):
				return (SSH.Product.LibSSH, version_desc[2:])
			else:
				return (SSH.Product.OpenSSH, version_desc)
		
		@classmethod
		def get_timeframe(cls, versions, for_server=True, result=None):
			# type: (List[Optional[str]], bool, Optional[Dict[str, List[Optional[str]]]]) -> Dict[str, List[Optional[str]]]
			result = result or {}
			vlen = len(versions)
			for i in range(3):
				if i > vlen - 1:
					if i == 2 and vlen > 1:
						cversions = versions[1]
					else:
						continue
				else:
					cversions = versions[i]
				if cversions is None:
					continue
				for v in cversions.split(','):
					ssh_prefix, ssh_version = cls.get_ssh_version(v)
					if not ssh_version:
						continue
					if ssh_version.endswith('C'):
						if for_server:
							continue
						ssh_version = ssh_version[:-1]
					if ssh_prefix not in result:
						result[ssh_prefix] = [None, None, None]
					prev, push = result[ssh_prefix][i], False
					if prev is None:
						push = True
					elif i == 0 and prev < ssh_version:
						push = True
					elif i > 0 and prev > ssh_version:
						push = True
					if push:
						result[ssh_prefix][i] = ssh_version
			return result
		
		@classmethod
		def get_since_text(cls, versions):
			# type: (List[Optional[str]]) -> Optional[text_type]
			tv = []
			if len(versions) == 0 or versions[0] is None:
				return None
			for v in versions[0].split(','):
				ssh_prefix, ssh_version = cls.get_ssh_version(v)
				if not ssh_version:
					continue
				if ssh_prefix in [SSH.Product.LibSSH]:
					continue
				if ssh_version.endswith('C'):
					ssh_version = '{0} (client only)'.format(ssh_version[:-1])
				tv.append('{0} {1}'.format(ssh_prefix, ssh_version))
			if len(tv) == 0:
				return None
			return 'available since ' + ', '.join(tv).rstrip(', ')
	
	class Algorithms(object):
		def __init__(self, pkm, kex):
			# type: (Optional[SSH1.PublicKeyMessage], Optional[SSH2.Kex]) -> None
			self.__ssh1kex = pkm
			self.__ssh2kex = kex
		
		@property
		def ssh1kex(self):
			# type: () -> Optional[SSH1.PublicKeyMessage]
			return self.__ssh1kex
		
		@property
		def ssh2kex(self):
			# type: () -> Optional[SSH2.Kex]
			return self.__ssh2kex
		
		@property
		def ssh1(self):
			# type: () -> Optional[SSH.Algorithms.Item]
			if self.ssh1kex is None:
				return None
			item = SSH.Algorithms.Item(1, SSH1.KexDB.ALGORITHMS)
			item.add('key', [u'ssh-rsa1'])
			item.add('enc', self.ssh1kex.supported_ciphers)
			item.add('aut', self.ssh1kex.supported_authentications)
			return item
		
		@property
		def ssh2(self):
			# type: () -> Optional[SSH.Algorithms.Item]
			if self.ssh2kex is None:
				return None
			item = SSH.Algorithms.Item(2, SSH2.KexDB.ALGORITHMS)
			item.add('kex', self.ssh2kex.kex_algorithms)
			item.add('key', self.ssh2kex.key_algorithms)
			item.add('enc', self.ssh2kex.server.encryption)
			item.add('mac', self.ssh2kex.server.mac)
			return item
		
		@property
		def values(self):
			# type: () -> Iterable[SSH.Algorithms.Item]
			for item in [self.ssh1, self.ssh2]:
				if item is not None:
					yield item
		
		@property
		def maxlen(self):
			# type: () -> int
			def ml(items):
				# type: (Sequence[text_type]) -> int
				return max(len(i) for i in items)
			maxlen = 0
			if self.ssh1kex is not None:
				maxlen = max(ml(self.ssh1kex.supported_ciphers),
				             ml(self.ssh1kex.supported_authentications),
				             maxlen)
			if self.ssh2kex is not None:
				maxlen = max(ml(self.ssh2kex.kex_algorithms),
				             ml(self.ssh2kex.key_algorithms),
				             ml(self.ssh2kex.server.encryption),
				             ml(self.ssh2kex.server.mac),
				             maxlen)
			return maxlen
		
		def get_ssh_timeframe(self, for_server=True):
			# type: (bool) -> Dict[str, List[Optional[str]]]
			r = {}  # type: Dict[str, List[Optional[str]]]
			for alg_pair in self.values:
				alg_db = alg_pair.db
				for alg_type, alg_list in alg_pair.items():
					for alg_name in alg_list:
						alg_name_native = utils.to_ntext(alg_name)
						alg_desc = alg_db[alg_type].get(alg_name_native)
						if alg_desc is None:
							continue
						versions = alg_desc[0]
						r = SSH.Algorithm.get_timeframe(versions, for_server, r)
			return r
		
		def get_recommendations(self, software, for_server=True):
			# type: (Optional[SSH.Software], bool) -> Tuple[Optional[SSH.Software], Dict[int, Dict[str, Dict[str, Dict[str, int]]]]]
			# pylint: disable=too-many-locals,too-many-statements
			vproducts = [SSH.Product.OpenSSH,
			             SSH.Product.DropbearSSH,
			             SSH.Product.LibSSH]
			if software is not None:
				if software.product not in vproducts:
					software = None
			if software is None:
				ssh_timeframe = self.get_ssh_timeframe(for_server)
				for product in vproducts:
					if product not in ssh_timeframe:
						continue
					version = ssh_timeframe[product][0]
					if version is not None:
						software = SSH.Software(None, product, version, None, None)
						break
			rec = {}  # type: Dict[int, Dict[str, Dict[str, Dict[str, int]]]]
			if software is None:
				return software, rec
			for alg_pair in self.values:
				sshv, alg_db = alg_pair.sshv, alg_pair.db
				rec[sshv] = {}
				for alg_type, alg_list in alg_pair.items():
					if alg_type == 'aut':
						continue
					rec[sshv][alg_type] = {'add': {}, 'del': {}}
					for n, alg_desc in alg_db[alg_type].items():
						if alg_type == 'key' and '-cert-' in n:
							continue
						versions = alg_desc[0]
						if len(versions) == 0 or versions[0] is None:
							continue
						matches = False
						for v in versions[0].split(','):
							ssh_prefix, ssh_version = SSH.Algorithm.get_ssh_version(v)
							if not ssh_version:
								continue
							if ssh_prefix != software.product:
								continue
							if ssh_version.endswith('C'):
								if for_server:
									continue
								ssh_version = ssh_version[:-1]
							if software.compare_version(ssh_version) < 0:
								continue
							matches = True
							break
						if not matches:
							continue
						adl, faults = len(alg_desc), 0
						for i in range(1, 3):
							if not adl > i:
								continue
							fc = len(alg_desc[i])
							if fc > 0:
								faults += pow(10, 2 - i) * fc
						if n not in alg_list:
							if faults > 0:
								continue
							rec[sshv][alg_type]['add'][n] = 0
						else:
							if faults == 0:
								continue
							if n == 'diffie-hellman-group-exchange-sha256':
								if software.compare_version('7.3') < 0:
									continue
							rec[sshv][alg_type]['del'][n] = faults
					add_count = len(rec[sshv][alg_type]['add'])
					del_count = len(rec[sshv][alg_type]['del'])
					new_alg_count = len(alg_list) + add_count - del_count
					if new_alg_count < 1 and del_count > 0:
						mf = min(rec[sshv][alg_type]['del'].values())
						new_del = {}
						for k, cf in rec[sshv][alg_type]['del'].items():
							if cf != mf:
								new_del[k] = cf
						if del_count != len(new_del):
							rec[sshv][alg_type]['del'] = new_del
							new_alg_count += del_count - len(new_del)
					if new_alg_count < 1:
						del rec[sshv][alg_type]
					else:
						if add_count == 0:
							del rec[sshv][alg_type]['add']
						if del_count == 0:
							del rec[sshv][alg_type]['del']
						if len(rec[sshv][alg_type]) == 0:
							del rec[sshv][alg_type]
				if len(rec[sshv]) == 0:
					del rec[sshv]
			return software, rec
		
		class Item(object):
			def __init__(self, sshv, db):
				# type: (int, Dict[str, Dict[str, List[List[Optional[str]]]]]) -> None
				self.__sshv = sshv
				self.__db = db
				self.__storage = {}  # type: Dict[str, List[text_type]]
			
			@property
			def sshv(self):
				# type: () -> int
				return self.__sshv
			
			@property
			def db(self):
				# type: () -> Dict[str, Dict[str, List[List[Optional[str]]]]]
				return self.__db
			
			def add(self, key, value):
				# type: (str, List[text_type]) -> None
				self.__storage[key] = value
			
			def items(self):
				# type: () -> Iterable[Tuple[str, List[text_type]]]
				return self.__storage.items()
	
	class Security(object):  # pylint: disable=too-few-public-methods
		# pylint: disable=bad-whitespace
		CVE = {
			'Dropbear SSH': [
				['0.44', '2015.71', 1, 'CVE-2016-3116', 5.5, 'bypass command restrictions via xauth command injection'],
				['0.28', '2013.58', 1, 'CVE-2013-4434', 5.0, 'discover valid usernames through different time delays'],
				['0.28', '2013.58', 1, 'CVE-2013-4421', 5.0, 'cause DoS via a compressed packet (memory consumption)'],
				['0.52', '2011.54', 1, 'CVE-2012-0920', 7.1, 'execute arbitrary code or bypass command restrictions'],
				['0.40', '0.48.1',  1, 'CVE-2007-1099', 7.5, 'conduct a MitM attack (no warning for hostkey mismatch)'],
				['0.28', '0.47',    1, 'CVE-2006-1206', 7.5, 'cause DoS via large number of connections (slot exhaustion)'],
				['0.39', '0.47',    1, 'CVE-2006-0225', 4.6, 'execute arbitrary commands via scp with crafted filenames'],
				['0.28', '0.46',    1, 'CVE-2005-4178', 6.5, 'execute arbitrary code via buffer overflow vulnerability'],
				['0.28', '0.42',    1, 'CVE-2004-2486', 7.5, 'execute arbitrary code via DSS verification code']],
			'libssh': [
				['0.1',   '0.7.2',  1, 'CVE-2016-0739', 4.3, 'conduct a MitM attack (weakness in DH key generation)'],
				['0.5.1', '0.6.4',  1, 'CVE-2015-3146', 5.0, 'cause DoS via kex packets (null pointer dereference)'],
				['0.5.1', '0.6.3',  1, 'CVE-2014-8132', 5.0, 'cause DoS via kex init packet (dangling pointer)'],
				['0.4.7', '0.6.2',  1, 'CVE-2014-0017', 1.9, 'leak data via PRNG state reuse on forking servers'],
				['0.4.7', '0.5.3',  1, 'CVE-2013-0176', 4.3, 'cause DoS via kex packet (null pointer dereference)'],
				['0.4.7', '0.5.2',  1, 'CVE-2012-6063', 7.5, 'cause DoS or execute arbitrary code via sftp (double free)'],
				['0.4.7', '0.5.2',  1, 'CVE-2012-4562', 7.5, 'cause DoS or execute arbitrary code (overflow check)'],
				['0.4.7', '0.5.2',  1, 'CVE-2012-4561', 5.0, 'cause DoS via unspecified vectors (invalid pointer)'],
				['0.4.7', '0.5.2',  1, 'CVE-2012-4560', 7.5, 'cause DoS or execute arbitrary code (buffer overflow)'],
				['0.4.7', '0.5.2',  1, 'CVE-2012-4559', 6.8, 'cause DoS or execute arbitrary code (double free)']],
			'OpenSSH': [
				['7.2',     '7.2p2',   1, 'CVE-2016-6515',  7.8, 'cause DoS via long password string (crypt CPU consumption)'],
				['1.2.2',   '7.2',     1, 'CVE-2016-3115',  5.5, 'bypass command restrictions via crafted X11 forwarding data'],
				['5.4',     '7.1',     1, 'CVE-2016-1907',  5.0, 'cause DoS via crafted network traffic (out of bounds read)'],
				['5.4',     '7.1p1',   2, 'CVE-2016-0778',  4.6, 'cause DoS via requesting many forwardings (heap based buffer overflow)'],
				['5.0',     '7.1p1',   2, 'CVE-2016-0777',  4.0, 'leak data via allowing transfer of entire buffer'],
				['6.0',     '7.2p2',   5, 'CVE-2015-8325',  7.2, 'privilege escalation via triggering crafted environment'],
				['6.8',     '6.9',     5, 'CVE-2015-6565',  7.2, 'cause DoS via writing to a device (terminal disruption)'],
				['5.0',     '6.9',     5, 'CVE-2015-6564',  6.9, 'privilege escalation via leveraging sshd uid'],
				['5.0',     '6.9',     5, 'CVE-2015-6563',  1.9, 'conduct impersonation attack'],
				['6.9p1',   '6.9p1',   1, 'CVE-2015-5600',  8.5, 'cause Dos or aid in conduct brute force attack (CPU consumption)'],
				['6.0',     '6.6',     1, 'CVE-2015-5352',  4.3, 'bypass access restrictions via a specific connection'],
				['6.0',     '6.6',     2, 'CVE-2014-2653',  5.8, 'bypass SSHFP DNS RR check via unacceptable host certificate'],
				['5.0',     '6.5',     1, 'CVE-2014-2532',  5.8, 'bypass environment restrictions via specific string before wildcard'],
				['1.2',     '6.4',     1, 'CVE-2014-1692',  7.5, 'cause DoS via triggering error condition (memory corruption)'],
				['6.2',     '6.3',     1, 'CVE-2013-4548',  6.0, 'bypass command restrictions via crafted packet data'],
				['1.2',     '5.6',     1, 'CVE-2012-0814',  3.5, 'leak data via debug messages'],
				['1.2',     '5.8',     1, 'CVE-2011-5000',  3.5, 'cause DoS via large value in certain length field (memory consumption)'],
				['5.6',     '5.7',     2, 'CVE-2011-0539',  5.0, 'leak data or conduct hash collision attack'],
				['1.2',     '6.1',     1, 'CVE-2010-5107',  5.0, 'cause DoS via large number of connections (slot exhaustion)'],
				['1.2',     '5.8',     1, 'CVE-2010-4755',  4.0, 'cause DoS via crafted glob expression (CPU and memory consumption)'],
				['1.2',     '5.6',     1, 'CVE-2010-4478',  7.5, 'bypass authentication check via crafted values'],
				['4.3',     '4.8',     1, 'CVE-2009-2904',  6.9, 'privilege escalation via hard links to setuid programs'],
				['4.0',     '5.1',     1, 'CVE-2008-5161',  2.6, 'recover plaintext data from ciphertext'],
				['1.2',     '4.6',     1, 'CVE-2008-4109',  5.0, 'cause DoS via multiple login attempts (slot exhaustion)'],
				['1.2',     '4.8',     1, 'CVE-2008-1657',  6.5, 'bypass command restrictions via modifying session file'],
				['1.2.2',   '4.9',     1, 'CVE-2008-1483',  6.9, 'hijack forwarded X11 connections'],
				['4.0',     '4.6',     1, 'CVE-2007-4752',  7.5, 'privilege escalation via causing an X client to be trusted'],
				['4.3p2',   '4.3p2',   1, 'CVE-2007-3102',  4.3, 'allow attacker to write random data to audit log'],
				['1.2',     '4.6',     1, 'CVE-2007-2243',  5.0, 'discover valid usernames through different responses'],
				['4.4',     '4.4',     1, 'CVE-2006-5794',  7.5, 'bypass authentication'],
				['4.1',     '4.1p1',   1, 'CVE-2006-5229',  2.6, 'discover valid usernames through different time delays'],
				['1.2',     '4.3p2',   1, 'CVE-2006-5052',  5.0, 'discover valid usernames through different responses'],
				['1.2',     '4.3p2',   1, 'CVE-2006-5051',  9.3, 'cause DoS or execute arbitrary code (double free)'],
				['4.5',     '4.5',     1, 'CVE-2006-4925',  5.0, 'cause DoS via invalid protocol sequence (crash)'],
				['1.2',     '4.3p2',   1, 'CVE-2006-4924',  7.8, 'cause DoS via crafted packet (CPU consumption)'],
				['3.8.1p1', '3.8.1p1', 1, 'CVE-2006-0883',  5.0, 'cause DoS via connecting multiple times (client connection refusal)'],
				['3.0',     '4.2p1',   1, 'CVE-2006-0225',  4.6, 'execute arbitrary code'],
				['2.1',     '4.1p1',   1, 'CVE-2005-2798',  5.0, 'leak data about authentication credentials'],
				['3.5',     '3.5p1',   1, 'CVE-2004-2760',  6.8, 'leak data through different connection states'],
				['2.3',     '3.7.1p2', 1, 'CVE-2004-2069',  5.0, 'cause DoS via large number of connections (slot exhaustion)'],
				['3.0',     '3.4p1',   1, 'CVE-2004-0175',  4.3, 'leak data through directoy traversal'],
				['1.2',     '3.9p1',   1, 'CVE-2003-1562',  7.6, 'leak data about authentication credentials'],
				['3.1p1',   '3.7.1p1', 1, 'CVE-2003-0787',  7.5, 'privilege escalation via modifying stack'],
				['3.1p1',   '3.7.1p1', 1, 'CVE-2003-0786', 10.0, 'privilege escalation via bypassing authentication'],
				['1.0',     '3.7.1',   1, 'CVE-2003-0695',  7.5, 'cause DoS or execute arbitrary code'],
				['1.0',     '3.7',     1, 'CVE-2003-0693', 10.0, 'execute arbitrary code'],
				['3.0',     '3.6.1p2', 1, 'CVE-2003-0386',  7.5, 'bypass address restrictions for connection'],
				['3.1p1',   '3.6.1p1', 1, 'CVE-2003-0190',  5.0, 'discover valid usernames through different time delays'],
				['3.2.2',   '3.2.2',   1, 'CVE-2002-0765',  7.5, 'bypass authentication'],
				['1.2.2',   '3.3p1',   1, 'CVE-2002-0640', 10.0, 'execute arbitrary code'],
				['1.2.2',   '3.3p1',   1, 'CVE-2002-0639', 10.0, 'execute arbitrary code'],
				['2.1',     '3.2',     1, 'CVE-2002-0575',  7.5, 'privilege escalation'],
				['2.1',     '3.0.2p1', 2, 'CVE-2002-0083', 10.0, 'privilege escalation'],
				['3.0',     '3.0p1',   1, 'CVE-2001-1507',  7.5, 'bypass authentication'],
				['1.2.3',   '3.0.1p1', 5, 'CVE-2001-0872',  7.2, 'privilege escalation via crafted environment variables'],
				['1.2.3',   '2.1.1',   1, 'CVE-2001-0361',  4.0, 'recover plaintext from ciphertext'],
				['1.2',     '2.1',     1, 'CVE-2000-0525', 10.0, 'execute arbitrary code (improper privileges)']]
		}  # type: Dict[str, List[List[Any]]]
		TXT = {
			'Dropbear SSH': [
				['0.28', '0.34', 1, 'remote root exploit', 'remote format string buffer overflow exploit (exploit-db#387)']],
			'libssh': [
				['0.3.3', '0.3.3', 1, 'null pointer check', 'missing null pointer check in "crypt_set_algorithms_server"'],
				['0.3.3', '0.3.3', 1, 'integer overflow',   'integer overflow in "buffer_get_data"'],
				['0.3.3', '0.3.3', 3, 'heap overflow',      'heap overflow in "packet_decrypt"']]
		}  # type: Dict[str, List[List[Any]]]
	
	class Socket(ReadBuf, WriteBuf):
		class InsufficientReadException(Exception):
			pass
		
		SM_BANNER_SENT = 1
		
		def __init__(self, host, port):
			# type: (Optional[str], int) -> None
			super(SSH.Socket, self).__init__()
			self.__sock = None  # type: Optional[socket.socket]
			self.__block_size = 8
			self.__state = 0
			self.__header = []  # type: List[text_type]
			self.__banner = None  # type: Optional[SSH.Banner]
			if host is None:
				raise ValueError('undefined host')
			nport = utils.parse_int(port)
			if nport < 1 or nport > 65535:
				raise ValueError('invalid port: {0}'.format(port))
			self.__host = host
			self.__port = nport
		
		def _resolve(self, ipvo):
			# type: (Sequence[int]) -> Iterable[Tuple[int, Tuple[Any, ...]]]
			ipvo = tuple(filter(lambda x: x in (4, 6), utils.unique_seq(ipvo)))
			ipvo_len = len(ipvo)
			prefer_ipvo = ipvo_len > 0
			prefer_ipv4 = prefer_ipvo and ipvo[0] == 4
			if ipvo_len == 1:
				family = socket.AF_INET if ipvo[0] == 4 else socket.AF_INET6
			else:
				family = socket.AF_UNSPEC
			try:
				stype = socket.SOCK_STREAM
				r = socket.getaddrinfo(self.__host, self.__port, family, stype)
				if prefer_ipvo:
					r = sorted(r, key=lambda x: x[0], reverse=not prefer_ipv4)
				check = any(stype == rline[2] for rline in r)
				for (af, socktype, proto, canonname, addr) in r:
					if not check or socktype == socket.SOCK_STREAM:
						yield (af, addr)
			except socket.error as e:
				out.fail('[exception] {0}'.format(e))
				sys.exit(1)
		
		def connect(self, ipvo=(), cto=3.0, rto=5.0):
			# type: (Sequence[int], float, float) -> None
			err = None
			for (af, addr) in self._resolve(ipvo):
				s = None
				try:
					s = socket.socket(af, socket.SOCK_STREAM)
					s.settimeout(cto)
					s.connect(addr)
					s.settimeout(rto)
					self.__sock = s
					return
				except socket.error as e:
					err = e
					self._close_socket(s)
			if err is None:
				errm = 'host {0} has no DNS records'.format(self.__host)
			else:
				errt = (self.__host, self.__port, err)
				errm = 'cannot connect to {0} port {1}: {2}'.format(*errt)
			out.fail('[exception] {0}'.format(errm))
			sys.exit(1)
		
		def get_banner(self, sshv=2):
			# type: (int) -> Tuple[Optional[SSH.Banner], List[text_type], Optional[str]]
			if self.__sock is None:
				return self.__banner, self.__header, 'not connected'
			banner = 'SSH-{0}-OpenSSH_7.4'.format('1.5' if sshv == 1 else '2.0')
			rto = self.__sock.gettimeout()
			self.__sock.settimeout(0.7)
			s, e = self.recv()
			self.__sock.settimeout(rto)
			if s < 0:
				return self.__banner, self.__header, e
			if self.__state < self.SM_BANNER_SENT:
				self.send_banner(banner)
			e = None
			while self.__banner is None:
				if not s > 0:
					s, e = self.recv()
					if s < 0:
						break
				while self.__banner is None and self.unread_len > 0:
					line = self.read_line()
					if len(line.strip()) == 0:
						continue
					if self.__banner is None:
						self.__banner = SSH.Banner.parse(line)
						if self.__banner is not None:
							continue
					self.__header.append(line)
				s = 0
			return self.__banner, self.__header, e
		
		def recv(self, size=2048):
			# type: (int) -> Tuple[int, Optional[str]]
			if self.__sock is None:
				return (-1, 'not connected')
			try:
				data = self.__sock.recv(size)
			except socket.timeout:
				return (-1, 'timed out')
			except socket.error as e:
				if e.args[0] in (errno.EAGAIN, errno.EWOULDBLOCK):
					return (0, 'retry')
				return (-1, str(e.args[-1]))
			if len(data) == 0:
				return (-1, None)
			pos = self._buf.tell()
			self._buf.seek(0, 2)
			self._buf.write(data)
			self._len += len(data)
			self._buf.seek(pos, 0)
			return (len(data), None)
		
		def send(self, data):
			# type: (binary_type) -> Tuple[int, Optional[str]]
			if self.__sock is None:
				return (-1, 'not connected')
			try:
				self.__sock.send(data)
				return (0, None)
			except socket.error as e:
				return (-1, str(e.args[-1]))
			self.__sock.send(data)
		
		def send_banner(self, banner):
			# type: (str) -> None
			self.send(banner.encode() + b'\r\n')
			if self.__state < self.SM_BANNER_SENT:
				self.__state = self.SM_BANNER_SENT
		
		def ensure_read(self, size):
			# type: (int) -> None
			while self.unread_len < size:
				s, e = self.recv()
				if s < 0:
					raise SSH.Socket.InsufficientReadException(e)
		
		def read_packet(self, sshv=2):
			# type: (int) -> Tuple[int, binary_type]
			try:
				header = WriteBuf()
				self.ensure_read(4)
				packet_length = self.read_int()
				header.write_int(packet_length)
				# XXX: validate length
				if sshv == 1:
					padding_length = (8 - packet_length % 8)
					self.ensure_read(padding_length)
					padding = self.read(padding_length)
					header.write(padding)
					payload_length = packet_length
					check_size = padding_length + payload_length
				else:
					self.ensure_read(1)
					padding_length = self.read_byte()
					header.write_byte(padding_length)
					payload_length = packet_length - padding_length - 1
					check_size = 4 + 1 + payload_length + padding_length
				if check_size % self.__block_size != 0:
					out.fail('[exception] invalid ssh packet (block size)')
					sys.exit(1)
				self.ensure_read(payload_length)
				if sshv == 1:
					payload = self.read(payload_length - 4)
					header.write(payload)
					crc = self.read_int()
					header.write_int(crc)
				else:
					payload = self.read(payload_length)
					header.write(payload)
				packet_type = ord(payload[0:1])
				if sshv == 1:
					rcrc = SSH1.crc32(padding + payload)
					if crc != rcrc:
						out.fail('[exception] packet checksum CRC32 mismatch.')
						sys.exit(1)
				else:
					self.ensure_read(padding_length)
					padding = self.read(padding_length)
				payload = payload[1:]
				return packet_type, payload
			except SSH.Socket.InsufficientReadException as ex:
				if ex.args[0] is None:
					header.write(self.read(self.unread_len))
					e = header.write_flush().strip()
				else:
					e = ex.args[0].encode('utf-8')
				return (-1, e)
		
		def send_packet(self):
			# type: () -> Tuple[int, Optional[str]]
			payload = self.write_flush()
			padding = -(len(payload) + 5) % 8
			if padding < 4:
				padding += 8
			plen = len(payload) + padding + 1
			pad_bytes = b'\x00' * padding
			data = struct.pack('>Ib', plen, padding) + payload + pad_bytes
			return self.send(data)
		
		def _close_socket(self, s):
			# type: (Optional[socket.socket]) -> None
			try:
				if s is not None:
					s.shutdown(socket.SHUT_RDWR)
					s.close()  # pragma: nocover
			except:  # pylint: disable=bare-except
				pass
		
		def __del__(self):
			# type: () -> None
			self.__cleanup()
		
		def __cleanup(self):
			# type: () -> None
			self._close_socket(self.__sock)


class KexDH(object):  # pragma: nocover
	def __init__(self, alg, g, p):
		# type: (str, int, int) -> None
		self.__alg = alg
		self.__g = g
		self.__p = p
		self.__q = (self.__p - 1) // 2
		self.__x = 0
		self.__e = 0
	
	def send_init(self, s):
		# type: (SSH.Socket) -> None
		r = random.SystemRandom()
		self.__x = r.randrange(2, self.__q)
		self.__e = pow(self.__g, self.__x, self.__p)
		s.write_byte(SSH.Protocol.MSG_KEXDH_INIT)
		s.write_mpint2(self.__e)
		s.send_packet()


class KexGroup1(KexDH):  # pragma: nocover
	def __init__(self):
		# type: () -> None
		# rfc2409: second oakley group
		p = int('ffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024e088a67'
		        'cc74020bbea63b139b22514a08798e3404ddef9519b3cd3a431b302b0a6d'
		        'f25f14374fe1356d6d51c245e485b576625e7ec6f44c42e9a637ed6b0bff'
		        '5cb6f406b7edee386bfb5a899fa5ae9f24117c4b1fe649286651ece65381'
		        'ffffffffffffffff', 16)
		super(KexGroup1, self).__init__('sha1', 2, p)


class KexGroup14(KexDH):  # pragma: nocover
	def __init__(self):
		# type: () -> None
		# rfc3526: 2048-bit modp group
		p = int('ffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024e088a67'
		        'cc74020bbea63b139b22514a08798e3404ddef9519b3cd3a431b302b0a6d'
		        'f25f14374fe1356d6d51c245e485b576625e7ec6f44c42e9a637ed6b0bff'
		        '5cb6f406b7edee386bfb5a899fa5ae9f24117c4b1fe649286651ece45b3d'
		        'c2007cb8a163bf0598da48361c55d39a69163fa8fd24cf5f83655d23dca3'
		        'ad961c62f356208552bb9ed529077096966d670c354e4abc9804f1746c08'
		        'ca18217c32905e462e36ce3be39e772c180e86039b2783a2ec07a28fb5c5'
		        '5df06f4c52c9de2bcbf6955817183995497cea956ae515d2261898fa0510'
		        '15728e5a8aacaa68ffffffffffffffff', 16)
		super(KexGroup14, self).__init__('sha1', 2, p)


def output_algorithms(title, alg_db, alg_type, algorithms, maxlen=0):
	# type: (str, Dict[str, Dict[str, List[List[Optional[str]]]]], str, List[text_type], int) -> None
	with OutputBuffer() as obuf:
		for algorithm in algorithms:
			output_algorithm(alg_db, alg_type, algorithm, maxlen)
	if len(obuf) > 0:
		out.head('# ' + title)
		obuf.flush()
		out.sep()


def output_algorithm(alg_db, alg_type, alg_name, alg_max_len=0):
	# type: (Dict[str, Dict[str, List[List[Optional[str]]]]], str, text_type, int) -> None
	prefix = '(' + alg_type + ') '
	if alg_max_len == 0:
		alg_max_len = len(alg_name)
	padding = '' if out.batch else ' ' * (alg_max_len - len(alg_name))
	texts = []
	if len(alg_name.strip()) == 0:
		return
	alg_name_native = utils.to_ntext(alg_name)
	if alg_name_native in alg_db[alg_type]:
		alg_desc = alg_db[alg_type][alg_name_native]
		ldesc = len(alg_desc)
		for idx, level in enumerate(['fail', 'warn', 'info']):
			if level == 'info':
				versions = alg_desc[0]
				since_text = SSH.Algorithm.get_since_text(versions)
				if since_text:
					texts.append((level, since_text))
			idx = idx + 1
			if ldesc > idx:
				for t in alg_desc[idx]:
					if t is None:
						continue
					texts.append((level, t))
		if len(texts) == 0:
			texts.append(('info', ''))
	else:
		texts.append(('warn', 'unknown algorithm'))
	first = True
	for (level, text) in texts:
		f = getattr(out, level)
		text = '[' + level + '] ' + text
		if first:
			if first and level == 'info':
				f = out.good
			f(prefix + alg_name + padding + ' -- ' + text)
			first = False
		else:
			if out.verbose:
				f(prefix + alg_name + padding + ' -- ' + text)
			else:
				f(' ' * len(prefix + alg_name) + padding + ' `- ' + text)


def output_compatibility(algs, for_server=True):
	# type: (SSH.Algorithms, bool) -> None
	ssh_timeframe = algs.get_ssh_timeframe(for_server)
	vp = 1 if for_server else 2
	comp_text = []
	for sshd_name in [SSH.Product.OpenSSH, SSH.Product.DropbearSSH]:
		if sshd_name not in ssh_timeframe:
			continue
		v = ssh_timeframe[sshd_name]
		if v[0] is None:
			continue
		if v[vp] is None:
			comp_text.append('{0} {1}+'.format(sshd_name, v[0]))
		elif v[0] == v[vp]:
			comp_text.append('{0} {1}'.format(sshd_name, v[0]))
		else:
			software = SSH.Software(None, sshd_name, v[0], None, None)
			if software.compare_version(v[vp]) > 0:
				tfmt = '{0} {1}+ (some functionality from {2})'
			else:
				tfmt = '{0} {1}-{2}'
			comp_text.append(tfmt.format(sshd_name, v[0], v[vp]))
	if len(comp_text) > 0:
		out.good('(gen) compatibility: ' + ', '.join(comp_text))


def output_security_sub(sub, software, padlen):
	# type: (str, Optional[SSH.Software], int) -> None
	secdb = SSH.Security.CVE if sub == 'cve' else SSH.Security.TXT
	if software is None or software.product not in secdb:
		return
	for line in secdb[software.product]:
		vfrom, vtill = line[0:2]  # type: str, str
		if not software.between_versions(vfrom, vtill):
			continue
		target, name = line[2:4]  # type: int, str
		is_server, is_client = target & 1 == 1, target & 2 == 2
		is_local = target & 4 == 4
		if not is_server:
			continue
		p = '' if out.batch else ' ' * (padlen - len(name))
		if sub == 'cve':
			cvss, descr = line[4:6]  # type: float, str
			out.fail('(cve) {0}{1} -- ({2}) {3}'.format(name, p, cvss, descr))
		else:
			descr = line[4]
			out.fail('(sec) {0}{1} -- {2}'.format(name, p, descr))


def output_security(banner, padlen):
	# type: (Optional[SSH.Banner], int) -> None
	with OutputBuffer() as obuf:
		if banner is not None:
			software = SSH.Software.parse(banner)
			output_security_sub('cve', software, padlen)
			output_security_sub('txt', software, padlen)
	if len(obuf) > 0:
		out.head('# security')
		obuf.flush()
		out.sep()


def output_fingerprint(algs, sha256=True, padlen=0):
	# type: (SSH.Algorithms, bool, int) -> None
	with OutputBuffer() as obuf:
		fps = []
		if algs.ssh1kex is not None:
			name = 'ssh-rsa1'
			fp = SSH.Fingerprint(algs.ssh1kex.host_key_fingerprint_data)
			bits = algs.ssh1kex.host_key_bits
			fps.append((name, fp, bits))
		for fpp in fps:
			name, fp, bits = fpp
			fpo = fp.sha256 if sha256 else fp.md5
			p = '' if out.batch else ' ' * (padlen - len(name))
			out.good('(fin) {0}{1} -- {2} {3}'.format(name, p, bits, fpo))
	if len(obuf) > 0:
		out.head('# fingerprints')
		obuf.flush()
		out.sep()


def output_recommendations(algs, software, padlen=0):
	# type: (SSH.Algorithms, Optional[SSH.Software], int) -> None
	for_server = True
	with OutputBuffer() as obuf:
		software, alg_rec = algs.get_recommendations(software, for_server)
		for sshv in range(2, 0, -1):
			if sshv not in alg_rec:
				continue
			for alg_type in ['kex', 'key', 'enc', 'mac']:
				if alg_type not in alg_rec[sshv]:
					continue
				for action in ['del', 'add']:
					if action not in alg_rec[sshv][alg_type]:
						continue
					for name in alg_rec[sshv][alg_type][action]:
						p = '' if out.batch else ' ' * (padlen - len(name))
						if action == 'del':
							an, sg, fn = 'remove', '-', out.warn
							if alg_rec[sshv][alg_type][action][name] >= 10:
								fn = out.fail
						else:
							an, sg, fn = 'append', '+', out.good
						b = '(SSH{0})'.format(sshv) if sshv == 1 else ''
						fm = '(rec) {0}{1}{2}-- {3} algorithm to {4} {5}'
						fn(fm.format(sg, name, p, alg_type, an, b))
	if len(obuf) > 0:
		title = '(for {0})'.format(software.display(False)) if software else ''
		out.head('# algorithm recommendations {0}'.format(title))
		obuf.flush()
		out.sep()


def output(banner, header, kex=None, pkm=None):
	# type: (Optional[SSH.Banner], List[text_type], Optional[SSH2.Kex], Optional[SSH1.PublicKeyMessage]) -> None
	sshv = 1 if pkm else 2
	algs = SSH.Algorithms(pkm, kex)
	with OutputBuffer() as obuf:
		if len(header) > 0:
			out.info('(gen) header: ' + '\n'.join(header))
		if banner is not None:
			out.good('(gen) banner: {0}'.format(banner))
			if not banner.valid_ascii:
				# NOTE: RFC 4253, Section 4.2
				out.warn('(gen) banner contains non-printable ASCII')
			if sshv == 1 or banner.protocol[0] == 1:
				out.fail('(gen) protocol SSH1 enabled')
			software = SSH.Software.parse(banner)
			if software is not None:
				out.good('(gen) software: {0}'.format(software))
		else:
			software = None
		output_compatibility(algs)
		if kex is not None:
			compressions = [x for x in kex.server.compression if x != 'none']
			if len(compressions) > 0:
				cmptxt = 'enabled ({0})'.format(', '.join(compressions))
			else:
				cmptxt = 'disabled'
			out.good('(gen) compression: {0}'.format(cmptxt))
	if len(obuf) > 0:
		out.head('# general')
		obuf.flush()
		out.sep()
	maxlen = algs.maxlen + 1
	output_security(banner, maxlen)
	if pkm is not None:
		adb = SSH1.KexDB.ALGORITHMS
		ciphers = pkm.supported_ciphers
		auths = pkm.supported_authentications
		title, atype = 'SSH1 host-key algorithms', 'key'
		output_algorithms(title, adb, atype, ['ssh-rsa1'], maxlen)
		title, atype = 'SSH1 encryption algorithms (ciphers)', 'enc'
		output_algorithms(title, adb, atype, ciphers, maxlen)
		title, atype = 'SSH1 authentication types', 'aut'
		output_algorithms(title, adb, atype, auths, maxlen)
	if kex is not None:
		adb = SSH2.KexDB.ALGORITHMS
		title, atype = 'key exchange algorithms', 'kex'
		output_algorithms(title, adb, atype, kex.kex_algorithms, maxlen)
		title, atype = 'host-key algorithms', 'key'
		output_algorithms(title, adb, atype, kex.key_algorithms, maxlen)
		title, atype = 'encryption algorithms (ciphers)', 'enc'
		output_algorithms(title, adb, atype, kex.server.encryption, maxlen)
		title, atype = 'message authentication code algorithms', 'mac'
		output_algorithms(title, adb, atype, kex.server.mac, maxlen)
	output_recommendations(algs, software, maxlen)
	output_fingerprint(algs, True, maxlen)


class Utils(object):
	@classmethod
	def _type_err(cls, v, target):
		# type: (Any, text_type) -> TypeError
		return TypeError('cannot convert {0} to {1}'.format(type(v), target))
	
	@classmethod
	def to_bytes(cls, v, enc='utf-8'):
		# type: (Union[binary_type, text_type], str) -> binary_type
		if isinstance(v, binary_type):
			return v
		elif isinstance(v, text_type):
			return v.encode(enc)
		raise cls._type_err(v, 'bytes')
	
	@classmethod
	def to_utext(cls, v, enc='utf-8'):
		# type: (Union[text_type, binary_type], str) -> text_type
		if isinstance(v, text_type):
			return v
		elif isinstance(v, binary_type):
			return v.decode(enc)
		raise cls._type_err(v, 'unicode text')
	
	@classmethod
	def to_ntext(cls, v, enc='utf-8'):
		# type: (Union[text_type, binary_type], str) -> str
		if isinstance(v, str):
			return v
		elif isinstance(v, text_type):
			return v.encode(enc)  # PY2 only
		elif isinstance(v, binary_type):
			return v.decode(enc)  # PY3 only
		raise cls._type_err(v, 'native text')
	
	@classmethod
	def _is_ascii(cls, v, char_filter=lambda x: x <= 127):
		# type: (Union[text_type, str], Callable[[int], bool]) -> bool
		r = False
		if isinstance(v, (text_type, str)):
			for c in v:
				i = cls.ctoi(c)
				if not char_filter(i):
					return r
			r = True
		return r
	
	@classmethod
	def _to_ascii(cls, v, char_filter=lambda x: x <= 127, errors='replace'):
		# type: (Union[text_type, str], Callable[[int], bool], str) -> str
		if isinstance(v, (text_type, str)):
			r = bytearray()
			for c in v:
				i = cls.ctoi(c)
				if char_filter(i):
					r.append(i)
				else:
					if errors == 'ignore':
						continue
					r.append(63)
			return cls.to_ntext(r.decode('ascii'))
		raise cls._type_err(v, 'ascii')
	
	@classmethod
	def is_ascii(cls, v):
		# type: (Union[text_type, str]) -> bool
		return cls._is_ascii(v)
	
	@classmethod
	def to_ascii(cls, v, errors='replace'):
		# type: (Union[text_type, str], str) -> str
		return cls._to_ascii(v, errors=errors)
	
	@classmethod
	def is_print_ascii(cls, v):
		# type: (Union[text_type, str]) -> bool
		return cls._is_ascii(v, lambda x: x >= 32 and x <= 126)
	
	@classmethod
	def to_print_ascii(cls, v, errors='replace'):
		# type: (Union[text_type, str], str) -> str
		return cls._to_ascii(v, lambda x: x >= 32 and x <= 126, errors)
	
	@classmethod
	def unique_seq(cls, seq):
		# type: (Sequence[Any]) -> Sequence[Any]
		seen = set()  # type: Set[Any]
		
		def _seen_add(x):
			# type: (Any) -> bool
			seen.add(x)
			return False
		
		if isinstance(seq, tuple):
			return tuple(x for x in seq if x not in seen and not _seen_add(x))
		else:
			return [x for x in seq if x not in seen and not _seen_add(x)]
	
	@classmethod
	def ctoi(cls, c):
		# type: (Union[text_type, str, int]) -> int
		if isinstance(c, (text_type, str)):
			return ord(c[0])
		else:
			return c
	
	@staticmethod
	def parse_int(v):
		# type: (Any) -> int
		try:
			return int(v)
		except:  # pylint: disable=bare-except
			return 0


def audit(aconf, sshv=None):
	# type: (AuditConf, Optional[int]) -> None
	out.batch = aconf.batch
	out.colors = aconf.colors
	out.verbose = aconf.verbose
	out.minlevel = aconf.minlevel
	s = SSH.Socket(aconf.host, aconf.port)
	s.connect(aconf.ipvo)
	if sshv is None:
		sshv = 2 if aconf.ssh2 else 1
	err = None
	banner, header, err = s.get_banner(sshv)
	if banner is None:
		if err is None:
			err = '[exception] did not receive banner.'
		else:
			err = '[exception] did not receive banner: {0}'.format(err)
	if err is None:
		packet_type, payload = s.read_packet(sshv)
		if packet_type < 0:
			try:
				payload_txt = payload.decode('utf-8') if payload else u'empty'
			except UnicodeDecodeError:
				payload_txt = u'"{0}"'.format(repr(payload).lstrip('b')[1:-1])
			if payload_txt == u'Protocol major versions differ.':
				if sshv == 2 and aconf.ssh1:
					audit(aconf, 1)
					return
			err = '[exception] error reading packet ({0})'.format(payload_txt)
		else:
			err_pair = None
			if sshv == 1 and packet_type != SSH.Protocol.SMSG_PUBLIC_KEY:
				err_pair = ('SMSG_PUBLIC_KEY', SSH.Protocol.SMSG_PUBLIC_KEY)
			elif sshv == 2 and packet_type != SSH.Protocol.MSG_KEXINIT:
				err_pair = ('MSG_KEXINIT', SSH.Protocol.MSG_KEXINIT)
			if err_pair is not None:
				fmt = '[exception] did not receive {0} ({1}), ' + \
				      'instead received unknown message ({2})'
				err = fmt.format(err_pair[0], err_pair[1], packet_type)
	if err:
		output(banner, header)
		out.fail(err)
		sys.exit(1)
	if sshv == 1:
		pkm = SSH1.PublicKeyMessage.parse(payload)
		output(banner, header, pkm=pkm)
	elif sshv == 2:
		kex = SSH2.Kex.parse(payload)
		output(banner, header, kex=kex)


utils = Utils()
out = Output()
if __name__ == '__main__':  # pragma: nocover
	conf = AuditConf.from_cmdline(sys.argv[1:], usage)
	audit(conf)