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Revisiting prompting for user input during an interactive or scripted install of ESXi

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For those that have a need to prompt for additional user input during an installation of ESXi, whether that is an interactive session or using a scripted install (Kickstart) may have noticed the solution posted in my 2015 blog post no longer works with recent releases of ESXi (newer than 6.0).


I was recently contacted by VMTN community cacheman, who authored the original snippet after my 2011 post with an updated solution that would work with newer releases of ESXi (e.g. 6.5 or newer). Thanks to Chris, he discovered the following after taking another look at the initial hack:

It seems that the tty1 techsupport.sh which I had commented out in /etc/inittab is having no effect in these versions and the login prompt is starting on tty1. As far as I can tell this is because for versions >= 6.5, the init process starts before the extras.tgz is unpacked, so it reads the /etc/inittab that comes natively with ESXi rather than the modified one in extras.tgz.

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Using ESXi Kickstart %firstboot with Secure Boot

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If you install ESXi via a Kickstart script and make use of the %firstboot option to execute commands on the first boot of the ESXi host after installation, you should be aware of its incompatibility with the Secure Boot feature. If you install ESXi where Secure Boot is enabled, the Kickstart will install ESXi normally only execute up to the %post section. However, it will not execute the %firstboot scripts and if you look at the /var/log/kickstart.log after the host boots, you should see the following message:

INFO UEFI Secure Boot Enabled, skipping execution of /var/lib/vmware/firstboot/001.firstboot_001

If you have Secure Boot enabled, %firstboot is not supported. The reason for this is Secure Boot mandates only known tardisks which can hold executable scripts, and a kickstart script is an unknown source so it can not run when Secure Boot is enabled. If you wish to continue using %firstboot scripts, the only option is to disable Secure Boot and then re-enable it after the installation. A preferred alternative is to convert your %firstboot logic into an external script which can then be applied using the vSphere API (recommended method) and this way you can still customize your ESXi host after the initial installations. I have already filed an internal documentation bug to add a note regarding Secure Boot and %firstboot, hopefully that will roll out with the net documentation refresh.

Quick Tip - What hashing algorithm is supported for ESXi Kickstart password?

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I had a question the other day asking whether the encrypted password which can be specified within an ESXi Kickstart file (denoted by the --isencrypted flag) can use a different hashing algorithm other than MD5? The answer is absolutely yes. In fact, MD5 as a default hashing algorithm has NOT been used for a number of releases, probably dating back to classic ESX (you know, the version that had the Service Console).

For all recent releases of ESXi including 5.5 to 6.7, the default hashing algorithm has been SHA512 for quite some time now. Below are two ways in which you can check which default hashing algorithm is currently being used:

Option 1 - SSH to ESXi host and take a look at /etc/pam.d/passwd


Option 2 - SSH to ESXi host and take a look at /etc/shadow and look at the field prior to the salt.

As a reference:

  • $1$ - MD5
  • $5$ - SHA256
  • $6$ - SHA512