title: Python returning an error when I try to run paramiko
body: <p>When I try to use the paramiko module it returns an error. I have tried to install  cliff/python cliff module but that hasn't solved the problem. I've also followed the recommendations here: <a href="https://stackoverflow.com/questions/38166531/python-pip-install-requestsecurity-have-error">Python pip install request[security] have error</a> without success. Does any one know how to do this? Thanks.</p>
  
  <pre><code>import paramiko
  paramiko.util.log_to_file("filename.log")
  def connect():
      client=paramiko.SSHClient()
      client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
      client.connect('192.168.0.100',username='XXX',password='XXX')
      chan = client.get_transport().open_session()
      chan.send("Hello")
      print chan.recv(1024)
  connect()
  </code></pre>
  
  <p>Here is the error log:</p>
  
  <pre><code>DEB [20160703-06:53:33.249] thr=1   paramiko.transport: starting thread (client mode): 0xb53dd250L
  DEB [20160703-06:53:33.249] thr=1   paramiko.transport: Local version/idstring: SSH-2.0-paramiko_2.0.1
  DEB [20160703-06:53:33.305] thr=1   paramiko.transport: Remote version/idstring: SSH-2.0-paramiko_1.15.3
  INF [20160703-06:53:33.305] thr=1   paramiko.transport: Connected (version 2.0, client paramiko_1.15.3)
  DEB [20160703-06:53:33.306] thr=1   paramiko.transport: kex algos:[u'diffie-hellman-group14-sha1', u'diffie-hellman-group-exchange-sha1', u'diffie-hellman-group1-sha1'] server key:[u'ssh-rsa'] client encrypt:[u'aes128-ctr', u'aes256-ctr', u'aes128-cbc', u'blowfish-cbc', u'aes256-cbc', u'3des-cbc', u'arcfour128', u'arcfour256'] server encrypt:[u'aes128-ctr', u'aes256-ctr', u'aes128-cbc', u'blowfish-cbc', u'aes256-cbc', u'3des-cbc', u'arcfour128', u'arcfour256'] client mac:[u'hmac-sha1', u'hmac-md5', u'hmac-sha1-96', u'hmac-md5-96'] server mac:[u'hmac-sha1', u'hmac-md5', u'hmac-sha1-96', u'hmac-md5-96'] client compress:[u'none'] server compress:[u'none'] client lang:[u''] server lang:[u''] kex follows?False
  DEB [20160703-06:53:33.306] thr=1   paramiko.transport: Kex agreed: diffie-hellman-group1-sha1
  DEB [20160703-06:53:33.306] thr=1   paramiko.transport: Cipher agreed: aes128-ctr
  DEB [20160703-06:53:33.306] thr=1   paramiko.transport: MAC agreed: hmac-md5
  DEB [20160703-06:53:33.306] thr=1   paramiko.transport: Compression agreed: none
  ERR [20160703-06:53:33.350] thr=1   paramiko.transport: Unknown exception: No     module named _cffi_backend
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport: Traceback (most recent call last):
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/paramiko/transport.py", line 1772, in run
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:     self.kex_engine.parse_next(ptype, m)
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/paramiko/kex_group1.py", line 75, in parse_next
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:     return self._parse_kexdh_reply(m)
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/paramiko/kex_group1.py", line 111, in _parse_kexdh_reply
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:     self.transport._verify_key(host_key, sig)
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/paramiko/transport.py", line 1617, in _verify_key
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:     key = self._key_info[self.host_key_type](Message(host_key))
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/paramiko/rsakey.py", line 58, in __init__
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:     ).public_key(default_backend())
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/cryptography/hazmat/backends/__init__.py", line 35, in default_backend
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:     _default_backend = MultiBackend(_available_backends())
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/cryptography/hazmat/backends/__init__.py", line 22, in _available_backends
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:     "cryptography.backends"
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2235, in     resolve
  ERR [20160703-06:53:33.353] thr=1   paramiko.transport:     module = __import__(self.module_name, fromlist=['__name__'], level=0)
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/cryptography/hazmat/backends/openssl/__init__.py", line 7, in &lt;module&gt;
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:     from cryptography.hazmat.backends.openssl.backend import backend
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/cryptography/hazmat/backends/openssl/backend.py", line 15, in &lt;module&gt;
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:     from cryptography     import utils, x509
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/cryptography/x509/__init__.py", line 7, in &lt;module&gt;
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:     from cryptography.x509.base import (
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/cryptography/x509/base.py", line 15, in &lt;module&gt;
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:     from cryptography.x509.extensions import Extension, ExtensionType
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/cryptography/x509/extensions.py", line 19, in &lt;module&gt;
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:     from cryptography.hazmat.primitives import constant_time, serialization
  ERR [20160703-06:53:33.354] thr=1   paramiko.transport:   File "/usr/local/lib/python2.7/dist-packages/cryptography/hazmat/primitives/constant_time.py", line 9, in &lt;module&gt;
  ERR [20160703-06:53:33.358] thr=1   paramiko.transport:     from cryptography.hazmat.bindings._constant_time import lib
  ERR [20160703-06:53:33.358] thr=1   paramiko.transport: ImportError: No     module named _cffi_backend
  ERR [20160703-06:53:33.358] thr=1   paramiko.transport:
  </code></pre>