*** Warning: Expected privileged user 'cyg_server' does not exist.
*** Warning: Defaulting to 'SYSTEM'

>>> import paramiko
>>> ssh=paramiko.SSHClient()
>>> ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
>>> ssh.connect(hostname='10.xx.xx.xx',username='xxxxx', password=u'xxx',key_filename=u'/home/xxxxx/.ssh/id_rsa',timeout=30.0, allow_agent=False, look_for_keys=False,)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/ute/python/lib/python2.7/site-packages/paramiko/client.py", line 424, in connect
    passphrase,
  File "/opt/ute/python/lib/python2.7/site-packages/paramiko/client.py", line 714, in _auth
    raise saved_exception
paramiko.ssh_exception.SSHException: No existing session

$ net user cyg_server
User name                    cyg_server
Full Name                    Privileged server
Comment                      <cygwin home="/var/empty" shell="/bin/false"/>
User's comment
Country code                 000 (System Default)
Account active               Yes

$ net user SYSTEM
The user name could not be found.

More help is available by typing NET HELPMSG 2221.

*** Info: The sshd service has been installed under the 'cyg_server'