title: vertica install failing with ssh error
body: <p>I was trying to install vertica using <code>/opt/vertica/sbin/install_vertica</code> script and following command <code>/opt/vertica/sbin/install_vertica -s vertica001,vertica002,vertica003 -r /root/packages/vertica-6.0.1-7.x86_64.RHEL5.rpm</code></p>
  
  <p>I was getting following error</p>
  
  <pre><code>Vertica Analytic Database 6.0.1-7 Installation Tool
  Starting installation tasks...
  Getting system information for cluster (this may take a while)....
  'failed to login to 172.16.10.212: EOF ERROR: Could not login with SSH. Here is what SSH said:  (publickey,gssapi-keyex,gssapi-with-mic).\r\r\n'
  
  Updating Nodes that are UP
  
  'failed to login to 172.16.10.18: EOF ERROR: Could not login with SSH. Here is what SSH said:  (publickey,gssapi-keyex,gssapi-with-mic).\r\r\n'
  
  Updating Nodes that are UP
  
  Removing 172.16.10.212,172.16.10.18 from hosts list
  backing up admintools.conf on 172.16.10.52
  Info: the package 'pstack' is useful during troubleshooting. Vertica recommends this package is installed.
  Checking/fixing OS parameters.....
  
  Error: No JSON object could be decoded
  Traceback (most recent call last):
  File "/opt/vertica/bin/verticaInstall.py", line 1187, in &lt;module&gt;
  if not SSH.check_min_free_kbytes(installerSSH, fix=True):
  File "/opt/vertica/oss/python/lib/python2.7/site-packages/vertica/network/SSH.py", line 2388, in check_min_free_kbytes
  data =json.loads( ''.join(res[host][1]))
  File "/opt/vertica/oss/python/lib/python2.7/json/__init__.py", line 310, in loads
  return _default_decoder.decode(s)
  File "/opt/vertica/oss/python/lib/python2.7/json/decoder.py", line 346, in decode
  obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/opt/vertica/oss/python/lib/python2.7/json/decoder.py", line 364, in raw_decode
  raise ValueError("No JSON object could be decoded")
  ValueError: No JSON object could be decoded
  </code></pre>
  
  <p>I have setup passwordless ssh for dbadmin also it has sudo access. </p>
  
  <p>Do I need to have passwordless ssh for root user here ? what I am missing here ?</p>