Information:
To properly setup Public and Private key pairs on your ESX server for use with Plink.exe or other SSH utilities you can do the following.
Note: Public Key authentication done on a per user basis, and the user must have SSH access to the ESX host.
1) Use PuttyGen.exe to create a public and private key for use with a specified user on the ESX Host
a. Save the files as follows
b. username-public.pub
c. username-private.ppk
d. authorized_keys (Cut and paste from the PuttyGen GUI)

2) Login to the ESX host with a user that has SSH permissions.
a. By default the root user can not telnet, SSH, or SCP, etc to the ESX Host. You must grant another user SSH access then issue the su --login command to gain root privileges.
3) Create the .ssh/authorized_keys folder and file in the user home folder.
a. The user home folder is the folder the user is placed in after logon.
b. In the user home folder create an .ssh folder
i. mkdir .ssh
1. By default the .ssh folder is hidden.
c. Change to the .ssh folder
i. cd .ssh
d. Create the authorized_keys file using Nano
i. nano authorized_keys
1. Copy and paste the information from the authorized_keys file created earlier in authorized_keys file on the ESX host.
2. Note: the pasted information should be a single line with spaces in the two shown loacations; after ssh-rsa and after the equal sign (=).
a. Example: ssh-rsa 123RandomKey123Abreviated= rsa-key-20091028
ii. Ctrl-O to write the file
iii. Ctrl-X to close Nano
4) To test the connection to the ESX host run the following command
a. plink -l username esxhost -i username-private.ppk vmware -v
b. Reply YES to store information in registry.
More Information:
To run multiple commands from plink.exe use the –m file option or separate each command on the command line with a semi-colon (;).
plink -l username esxhost -i username-private.ppk vmware –v; vmware --help