Keywords: PuTTY, root, ESX, secure shell, remote shell
If you start using VMWare ESX server 3.5 without reading documentation, you will be surprised to see that you can’t connect to ESX server via PuTTY or any remote secure shell with root account. It’s because, VMWare blocks root access to secure shell by default.
So you would be asking how do I connect to ESX server remotely. The right answer is create a casual user account in ESX server (using web console or VMWare Virtual client).
Login using your casual user account via PuTTy . Use "su" to get into super user mode OR use "sudo" to run commands.
Hope that helps.