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Using Google Authenticator To Provide Two-Factor Authentication For ESXi

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Last year, I came across an interesting open source project called Google Authenticator, which provides two-factor authentication by using both a PAM (Pluggable Authentication Module) module and a mobile application for generating one-time passcodes. This project sparked my curiosity and I wanted to see if I could get Google Authenticator to run on ESXi to provide additional security by requiring two-factor authentication when attempting to login to the ESXi Shell. After several attempts, I failed to get Google Authenticator working on ESXi and eventually gave up. I reported the behavior I saw in my environment in the Issues section of the project which did not yield any responses and I thought that was the end of that experiment.

Almost eight months later, I received a surprising email from two VMware engineers who were also interested in the Google Authenticator project and were able to figure out how to get Google Authenticator to work on ESXi. In sharing their findings, it turns out that the solution was actually quite simple and it just required commenting out three lines of C Macros in the Google Authenticator source code (tweak is documented in this blog post here). I was able to confirm the engineers findings in my home lab and was also able to build a custom Google Authenticator VIB for ESXi to help with the setup.

Disclaimer: This is not officially supported by VMware, use at your own risk

Installing Google Authenticator Custom VIB / Offline Bundle

Prerequisite:

  • Ensure that your ESXi host's clock is in sync with a proper time source (skew should be < 4minutes)
  • Keep a separate SSH connection open to your ESXi host, in case something goes wrong you can easily revert the changes else you can potentially lock yourself out

Step 1 - Download either the Google Authenticator VIB vghetto-google-auth.vib or offline bundle vghetto-google-auth.zip and upload it to the datastore of your ESXi host

Step 2 - You will need to change the acceptance level of your ESXi host to Community Supported as this is a requirement for any custom VIBs created. Run the following ESXCLI command:

esxcli software acceptance set --level CommunitySupported

Step 3 - To install Google Authenticator VIB, you will need to run the following ESXCLI command and specify the full datastore path of the VIB:

esxcli software vib install -v /vmfs/volumes/mini-local-datastore-1/vghetto-google-auth.vib -f

To install the Google Authenticator offline bundle, you will run the same command but instead of using the -v argument, you will specify the -d

Step 4 - You can verify the Google Authenticator was installed successfully by running the following ESXCLI command:

esxcli software vib get -n vGhetto-goog-auth

 

Configuring Google Authenticator & ESXi Configurations

Step 1 - Download the Google Authenticator app for your mobile phone. In this example, I am using the iPhone's Google Authenticator mobile app.

Step 2 - Next you will need to configure Google Authenticator for the ESXi host, run the google-authenticator command in the ESXi Shell which will start the setup.

You should see a URL as well as the secret key which you will need to enter into your Google Authenticator mobile app. You can either manually add your ESXi host into the mobile app by entering the secret key OR copy and paste the URL into a web browser which provides a QRC code that the mobile app can just read.

For all the prompted questions, you can use yes for the defaults.

Step 3 - You will need to add the following configuration to your SSHD configuration under /etc/ssh/sshd_config

ChallengeResponseAuthentication yes

Step 4 - You will also need to add the following entry to the following PAM configuration files /etc/pam.d/login and /etc/pam.d/sshd

auth   required   pam_google_authenticator.so

To add the entry into both files on the ESXi Shell, run the following two commands:

sed -i -e '3iauth       required     pam_google_authenticator.so\' /etc/pam.d/login
sed -i -e '3iauth       required     pam_google_authenticator.so\' /etc/pam.d/sshd

Note:  To ensure the above configuration persists after a reboot, you will need to add the two sed commands to /etc/rc.local.d/local.sh for ESXi 5.1 or /etc/rc.local for ESXi 5.0 hosts which will automatically add the entries upon bootup. 

Finally, you will need to restart the SSH daemon for the changes to go into effect by running the following command:

/etc/init.d/SSH restart

Step 5 - To validate that everything was configured correctly, open a new SSH session to your ESXi host. Instead of seeing the usual password prompt, you should now see a verification code prompt. Open up your Google Authenticator mobile app and enter the code that is displayed for your ESXi host and then enter the root password.

If everything was correct, you should now be authorized and logged into your ESXi host

Though the configuration could be a bit more automated including adding each ESXi host to your mobile application, this is a pretty nifty and free solution to provide two-factor authentication for your ESXi hosts. I am curious to see if others are interested in such functionality within ESXi or if this would be useful? Feel free to leave a comment.

Big thanks to VMware engineers who helped me get this solution to work!

How To "Pause" (Not Suspend) A Virtual Machine In ESXi?

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Last week I received a very interesting question from a fellow blogger asking whether it was possible to "pause" (not suspend) a virtual machine running on ESXi. Today ESXi only supports the suspend operation which saves the current memory state of a virtual machine to disk. With a "pause" operation, the memory state of the virtual machine is not saved to disk, it is still preserved in the physical memory of the ESXi host. The main difference with a "pause" operation is the allocated memory is not released and this allows you to quickly resume a virtual machine almost instantly at the cost of holding onto physical memory.

The use case for this particular request was also quite interesting. The user had an NFS server that housed about 200 virtual machines that needed to be restarted and the goal was to minimize the impact to his virtual machines as much as possible. He opted out from suspending the virtual machines as it would have taken too long and decided on a more creative solution. He filled up the remainder capacity on the datastore which in effect caused all virtual machines to halt their I/O operations. Though not an ideal solution IMHO, this allowed him to restart the NFS server and then run a script for the virtual machines to retry their I/O operation once the NFS server was available again.

Based on the above scenario, he asked if it was possible to "pause" the virtual machines similar to a capability Hyper-V provides today which would have provided him a quicker way to resume the virtual machines. Thinking about the question for a bit, a virtual machine is just a VMX process running in ESXi and I wondered if this process could be paused like a UNIX/Linux process using the "kill" command. Well, it turns out, it can be!

Disclaimer: This is not officially supported by VMware, use at your own risk.

Using the kill command, you can pause the VMX process by sending the STOP signal and to resume the VMX process, you can send the CONT signal. Before getting started, you will need to identify the PID (Process ID) for the virtual machine's VMX process.

There are two methods of identifying the parent VMX PID, the easiest is using the following ESXCLI command:

esxcli vm process list


The PID for the virtual machine will be listed under the "VMX Cartel ID" and in this example I have a virtual machine called vcenter51-1 and on the right I am pinging the system to verify it is up and running. An alternative way of identifying the PID is to use "ps" by running the following command:

ps -c | grep -v grep | grep [vmname]

Note: Make sure you identify the parent PID of the virtual machine if you are using the above command as you will see multiple entries for the different VMX sub-processes.

To pause the VMX process, run the following command (substitute your PID):

kill -STOP [pid]

To resume VMX process, run the following command:

kill -CONT [pid]

Here is a screenshot of pausing and then resuming the virtual machine. You can also see where the pings stop as the virtual machine is paused and then resumed. Once the virtual machine was resumed, it operated exactly where it left off with no issues as far as I can tell.
 
Note: I have found that if you have VM monitoring enabled, there maybe issues resuming the virtual machine. This should only be done if you have VM monitoring disabled as it may not be properly aware that the VMX process being paused on purpose.

Though it is possible to pause a virtual machine, I am not sure I see too many valid use cases for this feature? Are there are use cases where this feature would actually be beneficial, feel free to leave a comment if you believe there are. For now, this is just another neat "notsupported" trick 😉

How To Quickly Get Started With The New VMware Puppet Modules

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Yesterday, VMware Automation gurus Nick Weaver and Nan Liu just announced the release of four awesome new VMware Puppet modules that can help you manage and configure vCenter Server (including ESXi) and vCloud Networking & Security (vShield). You can read all about the details here and here and if you were lucky enough to have attended PEX (Partner Exchange) you might even have caught the demo given by Nick in his session.

I have used Puppet in the past, but it was pretty limited and specifically in How to Deploy ESXi 5 Using Razor & Puppet. I thought this might be a good time to revisit Puppet and try out the new VMware Puppet modules. I took a look at some of the examples provided by Nan on his blog but for new users to Puppet, it may not provide enough details to quickly get started (including myself). I thought I document the minimal steps I took to quickly get started (I also ran into a few bugs which Nan has fixed).

Step 1 - Install Ubuntu Precise (Ubuntu Server 12.04 LTS - See more at: http://www.virtuallyghetto.com/2012/05/how-to-deploy-esxi-5-using-razor-puppet.html

Step 1 - Install Ubuntu Precise (Ubuntu Server 12.04 LTS). You can use other distros, I just choose Ubuntu as I had the image lying around.

Step 2 - Download Puppet Labs package repository by running the following commands:

wget http://apt.puppetlabs.com/puppetlabs-release-$(lsb_release -c | cut -f 2).deb
dpkg -i puppetlabs-release-$(lsb_release -c | cut -f 2).deb
apt-get update

Step 3 - Install all the necessary packages such as Ruby, Ruby Gems, Puppet, etc. by running the following commands:

apt-get install -y libxslt-dev libxml2-dev ruby rubygems puppet
gem install nokogiri
gem install net-ssh

Step 4 - Install the VMware Puppet modules by running the following command:

puppet module install vmware/vcsa
puppet module install vmware/vcenter
puppet module install vmware/vshield

To start using the VMware Puppet modules, you will need to create what's known as a manifest file that contains the resources which maps to the actions you wish to perform (e.g. configure a newly deployed VCSA appliance or create a Cluster in vCenter Server and add an ESXi host to that cluster). You can find a bunch of example manifest files in each of the Puppet modules, here is the path to each:

/etc/puppet/modules/vcsa/tests/
/etc/puppet/modules/vcenter/tests/
/etc/puppet/modules/vshield/tests/

You will see in some of the examples, they import a file in each directory called data.pp which contains the actual definitions of your VCSA, vCNS and ESXi hosts but you can also just specify that in the main manifest file as well for simplicity. The latter option provides more flexibility as you can easily reference various configurations for different environments. For your convenience, I have created the following manifest files that you can use and you just need to modify them to fit your environment.

Here is what my lab environment looks like and their respective IP Addresses for your reference (these must already be deployed and vCenter & vCNS does not need to be configured but just accessible over network):

vCenter Server = 172.30.0.135
vCloud Networking and Security = 172.30.0.136
ESXi Host = 172.30.0.137

Step 5 - As mentioned by Nan, a custom Rbvmomi was used and we will need to ensure our Puppet management host (Ubuntu system we are on) includes it. To ensure all the necessary packages are downloaded for us, we will use the rbvmomi.pp manifest file for our host and use Puppet to apply the policy. Replace management_server in rbvmomi.pp with the hostname or IP Address of your Ubuntu host and then run the following command:

puppet apply rbvmomi.pp

Note:  You can safely ignore the red warnings, it must not have liked something in my environment.

Step 6 - We will start off by configuring the VCSA so we can then perform operations such as adding in Datacenters, Clusters, ESXi hosts, etc. We will use the configure-vcsa.pp manifest file by running the following command:

puppet apply configure-vcsa.pp

Step 7 - Next we will create a Datacenter, Cluster and add our ESXi host by using the setup-vcenter.pp manifest file by running the following command:

puppet apply setup-vcenter.pp

Step 8 - We are now onto configuring vCloud Networking and Security and we will also associate it with our vCenter Server by using the configure-vcns.pp manifest file and running the following command:

puppet apply configure-vcns.pp

Step 9 - After configuring vCloud Networking and Security, we can now deploy a vCloud Networking and Security Edge Gateway to provide various networking services to our vSphere environment using the deploy-edge.pp and by running the following command:

puppet apply deploy-edge.pp

In about 5-10 minutes, you will have a fully configured vSphere environment that contains your vCenter Server, vCloud Networking and Security Manager and Edge Gateway and ESXi hosts all ready to start providing compute and networking services for your virtual machines and applications! I want to stress the above is a very simplistic example of what you can do with the new VMware Puppet modules. There are definitely more advanced capabilities provided in the modules and I would recommend you take a look in the samples directory of each module for more details.

Overall, I was pretty impressed with the VMware integration that Nick, Nan and team built with Puppet. This was a great learning experience for myself, I learned quite a bit with just trying out these modules and I think I might have found a reason to dive more into Puppet! 🙂

Big thanks to Nan for helping me out with some of my Puppet questions!