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Quick Tip - Easily identify source DHCP server using ESXi DCUI

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While installing the ESXi 7.0 Update 1 on one of my physical system, I happened to be in the "Configure Management Network" section of the ESXi Direct Console UI (DCUI) and noticed something I had never seen before. As shown in the screenshot, it now shows the IP Address of the DHCP server in which ESXi received the DHCP lease.


I had not noticed this before and after asking on Twitter, it looks like this is definitely a new enhancement that was added fairly recently. I did not see this in one of my ESXi 6.7 Update 3 deployments, but it may have came in a later patch but definitely new in ESXi 7.0 or greater. Not only is this a quick and easy way to identify the DHCP server being used but in case you need to track down an unexpected rogue DHCP server running, this will certainly come in handy as pointed out by John.

Customizing the ESXi DCUI to show number of VMs

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Last week there was a question that was posted internally asking if it was possible to customize the ESXi DCUI screen to include the number of Virtual Machines? Although there is nothing out of the box, you can in fact add add almost anything to the DCUI screen by modifying the /etc/vmware/welcome configuration file which I had blogged about several years back on adding a splash of color to the ESXi DCUI. There was even a recent VMware Fling that provides a VIB that applies a variety of DoD STIG implementations, one of which was to update the DCUI screen with some specific text.

However, instead of having to manually edit the file directly on the ESXi host, we also provide an API in the way of an ESXi Advanced Setting called Annotations.WelcomeMessage which can then be updated remotely using anyone of the vSphere SDK/CLIs that you are familiar with.

Here is an example PowerCLI snippet to connect to an ESXi host (you can also do this by connecting to vCenter Server) and extracting all Virtual Machines residing on the host and then updating the DCUI screen with the total number of VMs as well as the names of each VM. Obviously, if you have more than 10 or so VMs, it may not make much sense to actually list them as it will just run off the screen, but this just gives you an example of some of the things you can do leveraging the vSphere API or any other data that you might have at your disposal.

Connect-VIServer -Server 192.168.1.50 -User root -Password vmware123

$vms = Get-View -ViewType VirtualMachine -Property Name

$DCUIString = "{color:yellow}
                {esxproduct} {esxversion}

                Hostname: {hostname}
                IP: {ip}
                
                Virtual Machines: " + $vms.Count + "
{/color}
{color:white}
"

foreach ($vm in $vms) {
    $DCUIString += "`t`t" + $vm.Name + "`n"
}

Set-VMHostAdvancedConfiguration -Name Annotations.WelcomeMessage -Value $DCUIString

Disconnect-VIServer -Confirm:$false

Note: If you wish to only filter out powered on Virtual Machines, you can add the following: -Filter @{"Runtime.PowerState" = "PoweredOn"} to the end of the Get-View command

Here is a screenshot quick screenshot of what this would look like on the DCUI screen of your ESXi host:

displaying_vms_in_esxi_dcui_1
Note: You can actually run the DCUI over SSH, which can be useful for testing purposes without having to directly login to the console remotely. Take a look at this blog post here for more details.

One final thing to be aware of when editing the welcome message on your ESXi host is that it will also be displayed in the ESXi Embedded Host Client login page as shown in the screenshot below. Just something to be aware of in case you plan to make any sensitive information available as this can be seen without needing to login to the ESXi host (just like the DCUI interface).

displaying_vms_in_esxi_dcui_2

vCenter Server 6.0 Tidbits Part 6: Customizing VCSA's DCUI

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For those of you who have deployed the latest VCSA 6.0, you may have noticed that it now includes a DCUI interface similar to that of ESXi. Just like ESXi, it provides some basic functionality such as network configuration, restarting of the management interface, enabling SSH/Shell access and viewing support logs. For some customers, there is a mandatory requirement in terms of compliance to be able to display a security or warning banner prior to logging into a system which can also include interactive console UI's like the DCUI.

With ESXi, it was possible to customize the DCUI as seen in the screenshot below (more serious customizations are used in customer environments of course). For more details, please take a look at this blog post here.

dcui4
Luckily, with the VCSA 6.0, it is also now possible to customize some of the text on the DCUI interface. However, you will not have complete free range like you did with the ESXi's DCUI interface but will be specific part of the screen. Here is an example of what can be added to the VCSA's DCUI screen:

customizing-vcsa-dcui
There is a section before the IP Address and a section after the IP Address which you can append custom text. This is controlled by the following configuration file located in: /etc/vmware/appliance/dcui.cfg and specifically with the following two variables: CONNECTION_MESSAGE which is the message before the IP Address and CONNECTION_MESSAGE_AFTER_IP for the message after the IP Address.

Here is an example of what the above customization looks like:

{
    "PRODUCT_NAME": "VMware vCenter Server Appliance 6.0",
    "CONNECTION_MESSAGE_BEFORE_IP": "https://",
    "CONNECTION_PORT": "443",
    "CONNECTION_MESSAGE": "\n\t### Message BEFORE IP ###\n",
    "CONNECTION_MESSAGE_AFTER_IP": "\n\n\t### Message AFTER IP ###\n"
}

For the changes to take affect, you will need to reload the DCUI interface which you can do by running the following command:

kill $(ps -ef | grep dcui.py | grep -v grep | awk '{print $2}')