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snxconnect.py
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snxconnect.py
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#!/usr/bin/python
from __future__ import print_function, unicode_literals
import os
import os.path
import sys
import socket
try :
from urllib2 import build_opener, HTTPCookieProcessor, Request
from urllib import urlencode
from httplib import IncompleteRead
rsatype = long
except ImportError :
from urllib.request import build_opener, HTTPCookieProcessor, Request
from urllib.parse import urlencode
from http.client import IncompleteRead
rsatype = int
try :
from cookielib import LWPCookieJar
except ImportError :
from http.cookiejar import LWPCookieJar
from bs4 import BeautifulSoup
from getpass import getpass
from argparse import ArgumentParser
from netrc import netrc, NetrcParseError
from Crypto.PublicKey import RSA
from struct import pack, unpack
from subprocess import Popen, PIPE
from snxvpnversion import VERSION
""" Todo:
- timeout can be retrieved at /sslvpn/Portal/LoggedIn
Function to do this is RetrieveTimeoutVal (url_above) in portal
This seems to be in seconds. But my portal always displays
"nNextTimeout = 6;" content-type is text/javascript.
- We may want to get the RSA parameters from the javascript in the
received html, RSA pubkey will probably be different for different
deployments.
- Log debug logs to syslog
"""
if sys.version_info >= (3,) :
def b_ord (x) :
return x
else :
def b_ord (x) :
return ord (x)
def iterbytes (x) :
""" Compatibility with python3: Iterating over bytes returns int.
Adding insult to injury calling bytes (23) will return a bytes
object with length 23 filled with b'\0'. So we do this.
Note that we will have to flatten iterators like the one
resulting from a call to reversed.
>>> a = []
>>> for k in iterbytes (b'abcdef') :
... a.append (k)
>>> for k in iterbytes (reversed (b'abcdef')) :
... a.append (k)
>>> print (repr (b''.join (a)).lstrip ('b'))
'abcdeffedcba'
"""
if sys.version_info >= (3,) :
x = bytes (x)
else :
x = b''.join (x)
for i in range (len (x)) :
yield (x [i:i+1])
# end def iterbytes
class HTML_Requester (object) :
def __init__ (self, args) :
self.modulus = None
self.exponent = None
self.args = args
self.jar = j = LWPCookieJar ()
self.has_cookies = False
if self.args.cookiefile :
self.has_cookies = True
try :
j.load (self.args.cookiefile, ignore_discard = True)
except IOError :
self.has_cookies = False
self.opener = build_opener (HTTPCookieProcessor (j))
self.nextfile = args.file
# end def __init__
def call_snx (self) :
""" The snx binary usually lives in the default snxpath and is
setuid root. We call it with the undocumented '-Z' option.
When everything is well it forks a subprocess and exists
(daemonize). If an error occurs before forking we get the
result back on one of the file descriptors. If everything
goes well, the forked snx process opens a port on
localhost:7776 (I've found no way this can be configured)
and waits for us to pass the binary-encoded parameters via
this socket. It later sends back an answer. It seems to keep
the socket open, so we do another read to wait for snx to
terminate.
"""
sp = self.args.snxpath
snx = Popen ([sp, '-Z'], stdin = PIPE, stdout = PIPE, stderr = PIPE)
stdout, stderr = snx.communicate ('')
rc = snx.returncode
if rc != 0 :
print ("SNX terminated with error: %d %s%s" % (rc, stdout, stderr))
sock = socket.socket (socket.AF_INET, socket.SOCK_STREAM)
sock.connect (("127.0.0.1", 7776))
sock.sendall (self.snx_info)
answer = sock.recv (4096)
if self.args.debug :
f = open ('snxanswer', 'wb')
f.write (answer)
f.close ()
print ("SNX connected, to leave VPN open, leave this running!")
answer = sock.recv (4096) # should block until snx dies
# end def call_snx
def debug (self, s) :
if self.args.debug :
print (s)
# end def debug
def generate_snx_info (self) :
""" Communication with SNX (originally by the java framework) is
done via an undocumented binary format. We try to reproduce
this here. We asume native byte-order but we don't know if
snx binaries exist for other architectures with a different
byte-order.
"""
magic = b'\x13\x11\x00\x00'
length = 0x3d0
gw_ip = socket.gethostbyname(self.extender_vars ['host_name'])
gw_int = unpack("!I", socket.inet_aton(gw_ip))[0]
fmt = b'=4sLL64sL6s256s256s128s256sH'
info = pack \
( fmt
, magic
, length
, gw_int
, self.extender_vars ['host_name']
, int (self.extender_vars ['port'])
, b''
, self.extender_vars ['server_cn']
, self.extender_vars ['user_name']
, self.extender_vars ['password']
, self.extender_vars ['server_fingerprint']
, 1 # ???
)
assert len (info) == length + 8 # magic + length
self.snx_info = info
# end def generate_snx_info
def login (self) :
if self.has_cookies :
self.debug ("has cookie")
self.nextfile = 'Portal/Main'
self.open ()
self.debug (self.purl)
if self.purl.endswith ('Portal/Main') :
self.open ('sslvpn/SNX/extender')
self.parse_extender ()
self.generate_snx_info ()
return True
else :
# Forget Cookies, otherwise we get a 400 bad request later
self.jar.clear ()
self.next_file (self.purl)
self.debug (self.nextfile)
self.open ()
self.debug (self.purl)
# Get the RSA parameters from the javascript in the received html
for script in self.soup.find_all ('script') :
if 'RSA' in script.attrs.get ('src', '') :
self.next_file (script ['src'])
self.debug (self.nextfile)
break
else :
print ('No RSA javascript file found, cannot login')
return
self.open (do_soup = False)
self.parse_rsa_params ()
if not self.modulus :
# Error message already given in parse_rsa_params
return
for form in self.soup.find_all ('form') :
if 'id' in form.attrs and form ['id'] == 'loginForm' :
self.next_file (form ['action'])
assert form ['method'] == 'post'
break
self.debug (self.nextfile)
enc = PW_Encode (modulus = self.modulus, exponent = self.exponent)
d = dict \
( password = enc.encrypt (self.args.password)
, userName = self.args.username
, selectedRealm = self.args.realm
, loginType = self.args.login_type
, vpid_prefix = self.args.vpid_prefix
, HeightData = self.args.height_data
)
self.open (data = urlencode (d))
self.debug (self.purl)
self.debug (self.info)
while 'MultiChallenge' in self.purl :
d = self.parse_pw_response ()
otp = getpass ('One-time Password: ')
d ['password'] = enc.encrypt (otp)
self.debug ("nextfile: %s" % self.nextfile)
self.debug ("purl: %s" % self.purl)
self.open (data = urlencode (d))
self.debug ("info: %s" % self.info)
if self.purl.endswith ('Portal/Main') :
if self.args.save_cookies :
self.jar.save (self.args.cookiefile, ignore_discard = True)
self.debug ("purl: %s" % self.purl)
self.open ('sslvpn/SNX/extender')
self.debug (self.purl)
self.debug (self.info)
self.parse_extender ()
self.generate_snx_info ()
return True
else :
print ("Unexpected response, looking for MultiChallenge or Portal")
self.debug ("purl: %s" % self.purl)
return
# end def login
def next_file (self, fname) :
if fname.startswith ('/') :
self.nextfile = fname.lstrip ('/')
elif fname.startswith ('http') :
self.nextfile = fname.split ('/', 3)[-1]
else :
dir = self.nextfile.split ('/')
dir = dir [:-1]
fn = fname.split ('/')
self.nextfile = '/'.join (dir + fn)
# We might try to remove '..' elements in the future
# end def next_file
def open (self, filepart = None, data = None, do_soup = True) :
filepart = filepart or self.nextfile
url = '/'.join (('%s:/' % self.args.protocol, self.args.host, filepart))
if data :
data = data.encode ('ascii')
rq = Request (url, data)
self.f = f = self.opener.open (rq, timeout = 10)
if do_soup :
# Sometimes we get incomplete read. So we read everything
# the server sent us and hope this is ok. Note: This means
# we cannot pass the file to BeautifulSoup but need to read
# everything here.
try:
page = f.read ()
except IncompleteRead as e:
page = e.partial
self.soup = BeautifulSoup (page, "lxml")
self.purl = f.geturl ()
self.info = f.info ()
# end def open
def parse_extender (self) :
""" The SNX extender page contains the necessary credentials for
connecting the VPN. This information then passed to the snx
program via a socket.
"""
for script in self.soup.find_all ('script') :
if '/* Extender.user_name' in script.text :
break
else :
print ("Error retrieving extender variables")
return
for line in script.text.split ('\n') :
if '/* Extender.user_name' in line :
break
stmts = line.split (';')
vars = {}
for stmt in stmts :
try :
lhs, rhs = stmt.split ('=')
except ValueError :
break
try :
lhs = lhs.split ('.', 1)[1].strip ()
except IndexError :
continue
rhs = rhs.strip ().strip ('"')
vars [lhs] = rhs.encode ('utf-8')
self.extender_vars = vars
# end def parse_extender
def parse_pw_response (self) :
""" The password response contains another form where the
one-time password (in our case received via a message to the
phone) must be entered.
"""
for form in self.soup.find_all ('form') :
if 'name' in form.attrs and form ['name'] == 'MCForm' :
self.next_file (form ['action'])
assert form ['method'] == 'post'
break
d = {}
for input in form.find_all ('input') :
if input.attrs.get ('type') == 'password' :
continue
if 'name' not in input.attrs :
continue
if input ['name'] in ('password', 'btnCancel') :
continue
d [input ['name']] = input.attrs.get ('value', '')
return d
# end def parse_pw_response
def parse_rsa_params (self) :
keys = ('modulus', 'exponent')
vars = {}
for line in self.f :
line = line.decode ('utf-8')
for k in keys :
if 'var %s' % k in line :
val = line.strip ().rstrip (';')
val = val.split ('=', 1) [-1]
val = val.strip ().strip ("'")
vars [k] = val
break
if len (vars) == 2 :
break
else :
print ('No RSA parameters found, cannot login')
return
self.debug (repr (vars))
self.modulus = rsatype (vars ['modulus'], 16)
self.exponent = rsatype (vars ['exponent'], 16)
# end def parse_rsa_params
# end class HTML_Requester
class PW_Encode (object) :
""" RSA encryption module with special padding and reversing to be
compatible with checkpoints implementation.
Test with non-random padding to get known value:
>>> p = PW_Encode (testing = True)
>>> print (p.encrypt ('xyzzy'))
451c2d5b491ee22d6f7cdc5a20f320914668f8e01337625dfb7e0917b16750cfbafe38bfcb68824b30d5cc558fa1c6d542ff12ac8e1085b7a9040f624ab39f625cabd77d1d024c111e42fede782e089400d2c9b1d6987c0005698178222e8500243f12762bebba841eae331d17b290f80bca6c3f8a49522fb926646c24db3627
>>> print (p.encrypt ('XYZZYxyzzyXYZZYxyzzy'))
a529e86cf80dd131e3bdae1f6dbab76f67f674e42041dde801ebdb790ab0637d56cc82f52587f2d4d34d26c490eee3a1ebfd80df18ec41c4440370b1ecb2dec3f811e09d2248635dd8aab60a97293ec0315a70bf024b33e8a8a02582fbabc98dd72d913530151e78b47119924f45b711b9a1189d5eec5a20e6f9bc1d44bfd554
"""
def __init__ (self, modulus = None, exponent = None, testing = False) :
m = rsatype \
( b'c87e9e96ffde3ec47c3f116ea5ac0e15'
b'34490b3da6dbbedae1af50dc32bf1012'
b'bdb7e1ff67237e0302b48c8731f343ff'
b'644662de2bb21d2b033127660e525d58'
b'889f8f6f05744906dddc8f4b85e0916b'
b'5d9cf5b87093ed260238674f143801b7'
b'e58a18795adc9acefaf0f378326fea19'
b'9ac6e5a88be83a52d4a77b3bba5f1aed'
, 16
)
e = rsatype (b'010001', 16)
m = modulus or m
e = exponent or e
self.pubkey = RSA.construct ((m, e))
self.testing = testing
# end def __init__
def pad (self, txt) :
l = (self.pubkey.size () + 7) >> 3
r = []
r.append (b'\0')
# Note that first reversing and then encoding to utf-8 would
# *not* be correct!
for x in iterbytes (reversed (txt.encode ('utf-8'))) :
r.append (x)
r.append (b'\0')
n = l - len (r) - 2
if self.testing :
r.append (b'\1' * n)
else :
r.append (os.urandom (n))
r.append (b'\x02')
r.append (b'\x00')
return b''.join (reversed (r))
# end def pad
def encrypt (self, password) :
x = self.pad (password)
e = self.pubkey.encrypt (x, '')[0]
e = ''.join ('%02x' % b_ord (c) for c in reversed (e))
return e
# end def encrypt
# end class PW_Encode
def main () :
# First try to parse config-file ~/.snxvpnrc:
home = os.environ.get ('HOME')
cfgf = None
if home :
try :
cfgf = open (os.path.join (home, '.snxvpnrc'), 'rb')
except (OSError, IOError) :
pass
cfg = {}
boolopts = ['debug', 'save_cookies']
if cfgf :
for line in cfgf :
line = line.strip ().decode ('utf-8')
if line.startswith ('#') :
continue
k, v = line.split (None, 1)
if k == 'server' :
k = 'host'
k = k.replace ('-', '_')
if k in boolopts :
v = (v.lower () in ('true', 'yes'))
cfg [k] = v
host = cfg.get ('host', '')
cookiefile = cfg.get ('cookiefile', '%s/.snxcookies' % home)
cmd = ArgumentParser ()
cmd.add_argument \
( '-c', '--cookiefile'
, help = 'Specify cookiefile to save and attempt reconnect'
' default="%(default)s"'
, default = cookiefile
)
cmd.add_argument \
( '-D', '--debug'
, help = 'Debug handshake'
, action = 'store_true'
, default = cfg.get ('debug', None)
)
cmd.add_argument \
( '-F', '--file'
, help = 'File part of URL default="%(default)s"'
, default = cfg.get ('file', 'sslvpn/Login/Login')
)
cmd.add_argument \
( '-H', '--host'
, help = 'Host part of URL default="%(default)s"'
, default = host
, required = not host
)
cmd.add_argument \
( '--height-data'
, help = 'Height data in form, default "%(default)s"'
, default = cfg.get ('height_data', '')
)
cmd.add_argument \
( '-L', '--login-type'
, help = 'Login type, default="%(default)s"'
, default = cfg.get ('login_type', 'Standard')
)
cmd.add_argument \
( '-P', '--password'
, help = 'Login password, not a good idea to specify on commandline'
, default = cfg.get ('password', None)
)
cmd.add_argument \
( '-p', '--protocol'
, help = 'http or https, should *always* be https except for tests'
, default = cfg.get ('protocol', 'https')
)
cmd.add_argument \
( '-R', '--realm'
, help = 'Selected realm, default="%(default)s"'
, default = cfg.get ('realm', 'ssl_vpn')
)
cmd.add_argument \
( '-s', '--save-cookies'
, help = 'Save cookies to %(cookiefile)s, might be a security risk,'
' default is off' % locals ()
, action = 'store_true'
, default = cfg.get ('save_cookies', False)
)
cmd.add_argument \
( '-S', '--snxpath'
, help = 'snx binary to call, default="%(default)s", you might'
' want a full path here'
, default = cfg.get ('snxpath', 'snx')
)
cmd.add_argument \
( '-U', '--username'
, help = 'Login username, default="%(default)s"'
, default = cfg.get ('username', '')
)
cmd.add_argument \
( '-V', '--vpid-prefix'
, help = 'VPID prefix, default "%(default)s"'
, default = cfg.get ('vpid_prefix', '')
)
cmd.add_argument \
( '--version'
, help = 'Display version and exit'
, action = 'store_true'
)
args = cmd.parse_args ()
if args.version :
print ("snxconnect version %s by Ralf Schlatterbeck" % VERSION)
sys.exit (0)
if not args.username or not args.password :
n = a = None
try :
n = netrc ()
except (IOError, NetrcParseError) :
pass
if n :
a = n.authenticators (args.host)
if a :
un, dummy, pw = a
if not args.username :
args.username = un
if not args.password :
args.password = pw
if not args.password :
args.password = getpass ('Password: ')
rq = HTML_Requester (args)
result = rq.login ()
if result :
rq.call_snx ()
# end def main ()
if __name__ == '__main__' :
main ()