Monday, January 17, 2011

ESXi hidden console is no more hidden

First some history. As you probably know, in ESXi 3.x (released on december 2007) the Red Hat service console had been removed and replaced by a small Linux version. In this old ESXi version the only way to access the hidden service console (or "Tech Support Mode" as they called it at VmWare) was to use this sneaky unsupported method :
  • You had to physically move to your server room and sit at the console of the server. There was no way to access this console via a remote tool.
  • Once you were on the server console you had to press Alt-F1 to see the console log.
  • At that point there was no prompt apparently available for you to pass commands to the server. Furthermore if you typed something, it would not appear on the screen.
  • The only thing that you could do was to enter the magic command "unsupported" and then press enter. Again, this would not appear on the screen but nontheless it would activate the aforementioned “Tech Support Mode".
Once you had activated the "Tech Support Mode" you could log in with you ESXi 3.x server root password and, for instance, enable SSH by editing your inetd.conf configuration file. The procedure for activating SSH was quite simple but very well undocumented at the time:
  • Edit the inetd.conf file by typing "vi /etc/inetd.conf"
  • Remove the # in front of the SSH line
  • Reboot your ESXi server (or kill the inetd process and start it again)
With the new vSphere 4.1, the ESXi “hidden” "Tech support mode" (which is now abbreviated as "TSM") has been finally made public by VmWare, and this is a great news. Now I can stay at my desk with my cup of black coffee and enjoy sending remote commands to my ESXi without having that strange feeling of sneaking inside my own systems...

So, back to the present. You can today enable access the ESXi tiny service console and to SSH straight from the Direct Console User Interface (DCUI). Just:

  • Press F2

  • Enter your root password

  • Go to Troubleshooting Options

  • Enable either Remote Tech Support (SSH) or Local Tech Support.

Optionally, if you want to configure the TimeOut for TSM:
  • Select Modify Tech Support timeout and press Enter.
  • Enter the desired TimeOut value in minutes and press Enter. I suggest putting 10 minutes in here.

  • Press Esc three times to return to the main DCUI screen.
Note that the TimeOut setting won't terminate existing sessions. This setting will just tell the system to let people remotely connect for i.e. 10 minutes than will close the door. If you are already logged inside the system it will not halt your session.

Hope this helps!

 VMware ESXi: Planning, Implementation, and Security Mastering VMware vSphere 4 (Computer/Tech)

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