Taken from http://www.yellow-bricks.com/2008/08/10/howto-esxi-and-ssh/
By default this isn’t possible. But there’s a way to get this working, just do the following:
Go to the ESXi console and press alt+F1 Type: unsupported Enter the root password(No prompt, typing is blindly) At the prompt type “vi /etc/inetd.conf” Look for the line that starts with “#ssh” (you can search with pressing “/”) Remove the “#” (press the “x” if the cursor is on the character) Save “/etc/inetd.conf” by typing “:wq!” Restart the management service “/sbin/services.sh restart”
To create a valid account, you must meet a certain criteria (not listed anywhere) for the password, which includes a combination of :