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Is a DNS server still required when using a Static IP for VCSA?

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When deploying a vCenter Server Appliance (VCSA), customers have two options for setting up a static network address: using either a hostname (Fully Qualified Domain Name) or just a static IP Address (e.g. no DNS). In the first option when using an FQDN, it should be no surprise that you need to also specify a valid DNS Server which the VCSA UI/CLI Installer will automatically validate both the forward and reverse address. This is the most common deployment model for customers in both production as well as for development environments such as a vSphere home lab.

In the second scenario, where a static IP Address is used, a DNS server is not required because we are NOT using an FQDN for the hostname but rather an IP Address. Having said that, if you have ever used the VCSA UI or CLI, you will find that the DNS Server entry is actually a required field and you can not proceed without providing an address.

VCSA UI Installer:

VCSA CLI Installer:

"network": {
    "ip_family": "ipv4",
    "mode": "static",
    "ip": "192.168.30.151",
    "dns_servers": [
        "192.168.30.1"
    ],
    "prefix": "24",
    "gateway": "192.168.30.1",
    "system_name": "192.168.30.151"
}

As mentioned earlier, we know that it should not be required but currently the VCSA Installer is a bit overly cautious in its pre-checks and does require a value today. This is something that has already been shared internally and the team will be relaxing this requirement in the future.

With that said, this leads us back to the original question posed in the blog title, do we need a valid DNS server when using a static IP for the VCSA?

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Enabling shell access for Active Directory users via SSH to vCenter Server Appliance (VCSA)

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I had a question the other day on whether it was possible to enable shell access for Active Directory users when logging into the vCenter Server Appliance (VCSA) via SSH? The answer is yes and though this is documented here, it is not very clear whether this is only applicable to SSO-based users only. In any case, the process to enable this is pretty straight forward and simply requires two steps which I have outlined below.

Step 0 - Ensure that your VCSA and/or PSC is joined to Active Directory before proceeding to the next step. If not, take a look at the documentation here for more details.

Step 1 - Login to vSphere Web Client and under Administration->System Configuration->Nodes->Manage->Settings->Access, go ahead and enable boh SSH and bash shell options. The first setting turns on SSH to the VCSA and the second setting allows users (local, SSO and AD) to access the shell on the VCSA.


Step 2 - In the vSphere Web Client and under Administration->Single Sign-On->Users and Groups->Groups, select the SystemConfiguration.BaseShellAdministrators group and add either an AD User and/or Group that you wish to allow to access the shell.


Once you have completed the steps above, you can now SSH to your VCSA/PSC using the AD user (UPN format) that you had authorized earlier. In the example below, I am logging into one of my VCSA using user *protected email* and as you can see, I am placed into the appliance shell by default.


At this point I can access all the appliancesh commands just like I normally would if I had logged as a root or *protected email*.

If we wish to change to bash shell, we simply just type "shell" which will enable shell access, assuming you had performed Step 2.


One thing that I noticed is that the default home directory for the AD user is /var/lib/nobody and apparently that does not exists by default, so users end up in / directory by default after enabling shell access. I am not sure if this is also related, but the username shows up as nobody as you can see from the prompt. This is something I will share with Engineering to see if we can improve upon as I am sure most of you would rather see the user that is actually logged in.

The good news from an auditing and logging standpoint is that for operations that are logged, it does properly show the username even though the prompt is showing up as nobody.

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Quick Tip - List all open ports on the VCSA / PSC

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The list of required ports for both a vCenter Server Appliance (VCSA) and Platform Services Controller (PSC) are pretty well documented here (6.5), here (6.0) and here (5.5) for customers who require this information to setup external connectivity within their networking infrastructure. Having said that, it is may not always be clear on what ports are actually opened as they will usually depend on the type of deployment and the services that are running. Instead, some customers have inquired about getting a list of all open ports directly from the VCSA/PSC to ensure they have the actual configuration which can be used to build firewall rules and/or for auditing purposes.

Today, the only method is to login directly into the VCSA/PSC via SSH (you could also use GuestOps API, so that SSH is NOT required) and fetching this information using iptables. Hopefully, in the future, this can be made available as part of the VAMI API since it already covers some basic inbound firewall rule capabilities. In the mean time, below are examples of how to get all the open ports for both VCSA/PSC

Run the following command to view all open ports on VCSA/PSC:

iptables -L port_filter -n --line-numbers


You will notice in the output above, there is also a chain number on the far left side which is associated with each rule. This chain number can be used to inspect the rule further and some rules include a nice alias to help you identify what the port might be used for.

For example, we can run the following to inspect chain rule #30 and find out this port is being used for syslog. If we want the port number, we simply add the -n option.

iptables -L port_filter 30
iptables -L port_filter 30 -n


Not all of the firewall rules have an alias name and even if they do, it still may not be apparent on what service is opening that particular port. We can actually look at the firewall rule definitions which are located under /etc/vmware/appliance/firewall and you will see a JSON file for each of the VCSA/PSC services that require firewall rules to be opened up. For a given port, you can just grep in this directory to identify the service that is requiring the port.

For example, if we take a look at the vmware-syslog, we see that it requires tcp/udp 514 and tcp 1514 under the "rules" array which defines the list of external ports open. You can ignore the internal ports as those are not exposed to the outside world but used by internal services. In case the services are still not clear, you can always reference the port number back to the documentation which I had linked above to get more details about the particular port.