title: How to fix 'knife bootstrap ssh connection to client issue' in chef?
body: <p>i'm trying to add a chef client node from chef workstation using knife bootstrap command.But getting error message as '''ERROR: Train::Transports::SSHFailed: SSH session could not be established'''</p>
  
  <p>I have disabled iptables on chef client</p>
  
  <pre><code>[root@chefclient ~]# service iptables status
  Redirecting to /bin/systemctl status  iptables.service
  iptables.service - IPv4 firewall with iptables
     Loaded: loaded (/usr/lib/systemd/system/iptables.service; disabled)
     Active: inactive (dead)
  
  Jul 29 16:21:18 chefclient.jp.com systemd[1]: [/usr/lib/systemd/system/iptables.service:5] Unknown lvalue 'AssertPathExists' in... 'Unit'
  Hint: Some lines were ellipsized, use -l to show in full
  
  '''knife bootstrap 192.168.56.6 -N chefclient.jp.com -U root --sudo -i /root/Downloads/chefsetup.pem'''
  
  Getting result as:
  Connecting to 192.168.56.6
  WARN: [SSH] PTY requested: stderr will be merged into stdout
  The authenticity of host '192.168.56.6 ()' can't be established.
  fingerprint is SHA256:8x0e7QPub3Zj/2GFz5XSFZCABEbez6uVV/eR1MvYoIE.
  
  Are you sure you want to continue connecting
  ? (Y/N) Y
  WARN: [SSH] PTY requested: stderr will be merged into stdout
  WARN: [SSH] connection failed, terminating (#&lt;Net::SSH::AuthenticationFailed: Authentication failed for user root@192.168.56.6&gt;)
  ERROR: Train::Transports::SSHFailed: SSH session could not be established
  </code></pre>