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Extracting SSL Thumbprint from ESXi

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While browsing the VMTN forums earlier this week, I noticed an interesting request from a user who was trying to compile an inventory of the SHA1 Thumbprints for all his ESXi hosts. The challenge the user had, was that he was capturing this information manually by "looking" at the DCUI screen which is where the SHA1 Thumbprint for an ESXi host is displayed by default.

As you might have guessed, this can be very tedious and error prone by copying down this very long string by just looking at the screen. Even if you do not make a mistake copying this long string, I bet your eyes will eventually give out. Luckily, there are a few ways to retrieve this information and I will show you some methods to help automate this across all of your ESXi hosts.

UPDATE (05/22/16) - Here's how you can extract SSL Thumbprint using PowerShell

Option 1 - Retrieve SSL Thumbprint using the DCUI as shown above, this is going to be the most manual method.

Option 2 - If you have remote SSH or direct console access to ESXi Shell, you can login to your ESXi host and using openssl utility, you can retrieve the SSL Thumbprint which you can then use or copy off to a remote host.

openssl x509 -in /etc/vmware/ssl/rui.crt -fingerprint -sha1 -noout

Option 3 - You can remotely retrieve the SSL Thumbprint by leveraging just the openssl utility and you do not even need to login to the ESXi host. This not only allows you to retrieve the SSL Thumbprint from a centralized location, but you can easily automate this across all your hosts.

echo -n | openssl s_client -connect 172.30.0.252:443 2>/dev/null | openssl x509 -noout -fingerprint -sha1

Using Option 3, you can easily wrap this in a simple "for" loop to iterate through all your ESXi hosts as long as you have either the hostname/IP Address. Here is a simple shell script that you can use to iterate through all your ESXi hosts to extract the SSL Thumbprint.

In the script above, I have a list of three ESXi hosts and it is simply going through each host and executing the two commands to extract the SSL Thumbprint and displaying it on the screen.

Option 4 - You can also retrieve the SSL Thumbprint using the vSphere API, but the property is only displayed when it is connected to a vCenter Server. There is a property on the ESXi host called sslThumbprint that is populated when querying against the vCenter Server that is managing the ESXi host. You can use the vSphere Health Check script which captures this and other useful information about your vSphere infrastructure.

As you can see, there are several options on obtaining the SSL Thumbprint for an ESXi host, you definitely do not have to manually read it off the DCUI screen. Automation FTW again! 🙂

Auditing vMotion Migrations

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I saw an interesting question this week about auditing vMotion events and the number of times a VM has migrated to a particular ESX(i) host for license compliance. You can view this information using the Task/Events in your vCenter Server but you can also extract out the various types of events using the EventManager in the vSphere API. You will be able to go as far back in time as your vCenter Server's database retention policy allows you to. We will be searching for the VmMigratedEvent Event which will include variety of information including the source and destination host for the VM. The destination host will only be populated upon a successful vMotion.

Of course I had to write a script to help automate this, so here is a vSphere SDK for Perl script called getNumberOfvMotions.pl that accepts the name of an existing VM and will return the number of vMotions that has been performed on the VM as well as the list of destination hosts and the number of times it has migrated to those hosts. You will need a system that has the vCLI installed or you can you use vMA.

Note:  If you want to look at past vMotion for a VM that no longer exists, this is still possible, but you will need to parse the "message" within the Event as you can no longer look up that VM object in vCenter.

Here is an example of the script running:

You can easily modify the script to audit all VM's in your environment or just use a simple "for" loop to go through a set of VM's you are interested in, but I will leave that as an exercise for you.

How to Create Bootable ESXi 5 ISO & Specifying Kernel Boot Options

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This week I helped to answer a few questions about creating your own ESXi 5 bootable ISO along with automatically using a static IP Address when the custom ISO first boots up. Although all this information is available via the vSphere documentation, it may not always be easy to put all the pieces together and thought I share the steps for others to also benefit.

You will need access to a UNIX/Linux system and a copy of the base ESXi 5 ISO image. In this example I will be using VMware vMA and VMware-VMvisor-Installer-5.0.0.update01-623860.x86_64.iso and walk you through two different configurations. We will also be referencing the vSphere documentation Create an Installer ISO Image with a Custom Installation or Upgrade Script and Kernel Boot Options.

Create ESXi 5 Bootable ISO w/Remote ks.cfg:

In this configuration, we will create a custom ESXi ISO that will boot with a static IP Address and use a remote ks.cfg (kickstart) configuration file.

Step 1 - Mount base ESXi ISO using the "mount" utility:

$ mkdir esxi_cdrom_mount
$ sudo mount -o loop VMware-VMvisor-Installer-5.0.0.update01-623860.x86_64.iso esxi_cdrom_mount

Step 2 - Copy the contents of the mounted image to a local directory called "esxi_cdrom":

$  cp -r esxi_cdrom_mount esxi_cdrom

Step 3 - Unmount the ISO after you have successfully copied it and change into the esxi_cdrom directory

$ sudo umount esxi_cdrom_mount
$ cd esxi_cdrom

Step 4 - Edit the boot.cfg and specifically the "kernelopt" line to not use the weasel installer but kickstart and also specifying the remote location of your ks.cfg. To get more details on the various kernel boot options, please take a look at the vSphere Boot Options documentation above.

You will also need to specify the static IP Address you wish to have the host automatically use when the ISO first boots up on the same line.

Step 5 - Once you have finished your edits and saved the boot.cfg, you will now change back to the parent directory and use the "mkisofs" to create your new bootable ISO. In this example, we will name the new ISO "custom_esxi.iso":

$ sudo mkisofs -relaxed-filenames -J -R -o custom_esxi.iso -b isolinux.bin -c boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table esxi_cdrom/

You now have a new bootable ESXi 5 ISO called "custom_esxi.iso" which will now automatically boot up with the specified static IP Address and install based on the ks.cfg that was specified.

Create ESXi 5 Bootable ISO w/Local ks.cfg:

Similar to the above configuration, we will create a custom ESXi ISO that will boot with a static IP Address but use a local ks.cfg (kickstart) configuration file that will be included within the custom ISO.

Step 1 through 3 is exactly the same as above

Step 4 - By default, a basic ks.cfg is included in the ESXi 5 ISO in /etc/vmware/weasel/ks.cfg and we will create a custom *.tgz file that will include our ks.cfg within the ISO. First off by creating a temporary directory which will be used to store our ks.cfg:

$ mkdir -p temp/etc/vmware/weasel

Step 5 - Copy your ks.cfg file into the temp/etc/vmware/weasel:

$ cp ks_custom.cfg temp/etc/vmware/weasel

Step 6 - Create a *.tgz file containing the path to our ks.cfg using the "tar" utility. In this example, we will called it customks.tgz:

$ cd temp
$ tar czvf customks.tgz *

Step 7 -  Copy the customks.tgz from temp directory to your esxi_cdrom directory:

$ cp temp/customks.tgz esxi_cdrom

Step 8 -  Change into the "esxi_cdrom" directory and edit the boot.cfg just like the above, but we will be using the "file://" stanza to specify the path to our ks.cfg, static IP Address as well as adding our customks.tgz to the module list to ensure that it loads up which contains the actual ks.cfg file that is called in the boot.cfg.

Step 9 - Same as Step 5 above, you now just need to run the "mkisofs" utility to create your bootable ISO.

You now have a new bootable ESXi 5 ISO called "custom_esxi.iso" which will now automatically boot up with the specified static IP Address and install based on the ks.cfg that is included within the ISO.