How to enable the root login in the ESX server which is OFF by default?
Edit the configuration file for SSH with the command:
Find the line that starts with PermitRootLogin and change the no to yes. You can find this line about 2 pages down from the top.
Save the file by first pressing Ctrl-O and then Enter.
Exit with Ctrl-X.
Restart the sshd service with the command:
service sshd restart