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

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.

For auditing SSH logins, you can take a look at /var/log/messages and here is a snippet when logging in over SSH with AD user:

2017-10-04T19:05:34.595761+00:00 vcenter65-3 sshd[24899]: Accepted keyboard-interactive/pam for *protected email* from 172.30.0.121 port 56999 ssh2
2017-10-04T19:05:34.596753+00:00 vcenter65-3 sshd[24899]: pam_unix(sshd:session): session opened for user *protected email* by (uid=0)

For auditing all appliance shell operations (which are logged by default), you can take a look at /var/log/vmware/applmgmt-audit/applmgmt-audit-syslog.log and below is a snippet when running the system.update.get command:

17-10-04T19:02:45.338210+00:00 info applmgmt-audit 2017-10-04T19:02:45.277: INFO ---API Input Details---
17-10-04T19:03:04.027464+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO Authentication request -- "user:"*protected email*", action:"system.listMethods", result:"success"
17-10-04T19:03:04.041664+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO AuthenticationResult = { authenticated=True, userid=False username=*protected email*, role=superAdministrator, renew=False, auth_method=SSO }
17-10-04T19:03:04.043748+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO Authentication request -- "user:"*protected email*", action:"system.listMethods", result:"success"
17-10-04T19:03:04.044535+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO AuthenticationResult = { authenticated=True, userid=False username=*protected email*, role=superAdministrator, renew=False, auth_method=SSO }
17-10-04T19:03:04.058065+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO Authentication request -- "user:"*protected email*", action:"system.listMethods", result:"success"
17-10-04T19:03:04.059265+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO AuthenticationResult = { authenticated=True, userid=False username=*protected email*, role=superAdministrator, renew=False, auth_method=SSO }
17-10-04T19:03:04.076688+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO Authentication request -- "user:"*protected email*", action:"com.vmware.appliance.system.uptime.get", result:"success"
17-10-04T19:03:04.078043+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO AuthenticationResult = { authenticated=True, userid=False username=*protected email*, role=superAdministrator, renew=False, auth_method=SSO }
17-10-04T19:03:04.081941+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO Authorization Result: User=*protected email*, priv=ViewConfiguration, authorized=False
17-10-04T19:03:04.082454+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO Authorization Result: User=*protected email*, priv=ModifyLocalConf, authorized=True
17-10-04T19:03:04.083534+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO Authorization Result: User=*protected email*, priv=ModifyLocalConf, authorized=True
17-10-04T19:03:04.085034+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO ---API Input Details---
17-10-04T19:03:04.085501+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO Function : com.vmware.appliance.system.uptime.get
17-10-04T19:03:04.086017+00:00 info applmgmt-audit 2017-10-04T19:03:04.277: INFO ---API Input Details---

For general shell usage, as noted earlier when you logged into the VCSA, it is mostly NOT logged. Having said that, depending on the tools you use, it may still be logged at the application layer which you can find in some of the logs. In general, this is an area that Engineering is working on to improve and providing more comprehensive auditing capabilities for ANY user that accessing the VCSA whether that is via the API and/or direct shell access. If there is any feedback or requests that you may have, feel free to leave a comment and I will be sure to forward this off to the PM and the Engineering teams.