Establish passwordless ssh between ubuntu and ESX host.

Here we describe the procedure to establish passwordless SSH connection to ESX host from ubuntu machine.

• First, let us login into the local machine and generate the authentication key through the following command.

ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/giri/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/giri/.ssh/id_rsa.
Your public key has been saved in /home/giri/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:+7Rs50PhUaT2/ldhaB2nVoqx84o5GKsqbHvBPi+i/7c giri@giri-e2e
The key's randomart image is:
+---[RSA 2048]----+
|             ..  |
|            ....o|
|            o=o+o|
|           .*+++ |
|   .    S  ..*o .|
|    o   ..  o.. .|
| . . .  .+.+ .. .|
|  = = . o+=.+  ..|
|.+o*o*Eo .++..  o|
+----[SHA256]-----+

• After generating the key pair, the same has to be copied to the remote machine. In ESX, the location of ssh specific files are located in `/etc/ssh` directory. This is different from linux operating systems. So ,we need to copy the public key into that directory.

cat .ssh/id_rsa.pub | ssh xxxxx@192.168.xxx.xxx 'cat >> /etc/ssh/authorized_keys'

You will be prompted for remote machine’s password. After copying the public key successfully, the passwordless SSH to the remote machine will be established successfully.

user@machine1:~$ ssh root@192.168.xxx.xxx
The time and date of this login have been sent to the system logs.
VMware offers supported, powerful system administration tools.  Please
see www.vmware.com/go/sysadmintools for details.
The ESXi Shell can be disabled by an administrative user. See the
vSphere Security documentation for more information.
[root@esx:~]

Thus, we can enable passwordless SSH between linux and ESX host.