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resxtop bug in vCLI 4.1 not vMA 4.1

10.17.2010 by William Lam // Leave a Comment

I recently noticed a thread in the vMA forums regarding an issue using resxtop on vMA 4.1 to view VM disk statistics on an ESXi 4.0 hosts. The thread was started on July 26th 2010 and as far as I could tell, no resolution was ever provided. A recent comment that was left on Oct 14th 2010 by another user experiencing the same behavior got my attention while browsing the VMTN forums. I decided to perform a small test to see if this was in fact an issue and it turns out it maybe a bug in resxtop running on vMA 4.1.

The test environment consists of the following:

  • 1 x vESXi 4.0u2 running 1 VM
  • 1 x vESXi 4.1 running 1 VM
  • 1 x vMA 4.0
  • 1 x vMA 4.1

Here is a screenshot of running esxtop locally within Tech Support Mode (Busybox console) on the ESXi 4.0 hosts and you can see, the VM disk statistics are visible and present:

Here is a screenshot of running esxtop locally within Tech Support Mode (Busybox console) on the ESXi 4.1 hosts and you can see, the VM disk statistics are visible and present:

Now here is a screenshot of running both vMA 4.1 (on top) and vMA 4.0 (on bottom) connecting to an ESXi 4.0 host running a single virtual machine called VM2. I use resxtop to connect to the ESXi 4.0 and select "v" option or VM disk statistics and as you can see from the screenshot, no statistics are being displayed when using vMA 4.1:

I perform the same exact test but now connecting to an ESXi 4.1 host using both vMA 4.1 (on top) and vMA 4.0 (on bottom) and what is actually surprising is, the VM disk statistics shows up for both vMA 4.0 and vMA 4.1:

It looks like something changed in the resxtop binary between vMA 4.0 and vMA 4.1 that causes the the VM disk statistics on ESX(i) hosts running on 4.0 not to be visible. I have not found any VMware KB articles documenting this issue nor found anything in vMA's release notes in which this configuration is not supported. This looks like a bug to me and I will try follow-up with the vMA's product manager to get an official word.

Note: I used ESXi since it was quicker to deploy for this test, but the issue affects both ESX and ESXi 4.0 when using resxtop from vMA 4.1

UPDATE:  After further investigation, I found out the issue is in fact with vCLI 4.1 installation and not with vMA 4.1. To confirm, I spun up a CentOS VM and installed and individually tested vCLI 4.0u2 and vCLI 4.1 and experience the same behavior as in vMA. I have already reported the issue to vMA product manager and hopefully we can get this resolved in either a patch or an updated released.

Categories // Uncategorized Tags // resxtop, vma, vSphere 4.1

Why you should upgrade from vMA 4.0 to vMA 4.1

08.10.2010 by William Lam // 5 Comments

As you may know, with the release of vSphere 4.1, core vSphere components such as vCenter and ESX(i) all received significant feature updates. This was no exception with VMware vMA, though the number of updates were minimal but still signifcant.

Here is the list of new features:

  • Support for Windows Active Directory Integration using Likewise Open
  • Offline bundle support for upgrading vMA
  • Resolved major security flaw with vi-fastpass component

1. Support for Windows Active Directory Integration using Likewise Open
For those that use Active Directory, you now have the capability of centralizing your user management on vMA. Using Likewise's Open software, users can now login to vMA using their AD credentials. Not only can they login, but with the enhancement of the new vi-fastpass, you can now add a target and configure it to support AD authentication versus normal fastpass authentication. This means that the user who logs into vCenter can log into vMA to perform an operation such as adding a vSwitch or powering on a Virtual Machine without providing further credentials using this new AD authentication passthrough. For more details, take a look at this article vMA 4.1 Authentication Policy - fpauth vs adauth.

2. Offline bundle support for upgrading vMA
Prior to vMA 4.1, to upgrade the software within vMA, you had to use vima-update (now renamed to vma-update) which connects to VMware's online repository. This was an issue for envrionments that did not have direct internet or proxy access to VMware's website and there were no supported work arounds for this. You now can download an offline bundle just like you can for  ESX or ESXi and perform an offline upgrade.

3. Resolved major security flaw with vi-fastpass component
Saving the best for last. This has been a security issue that has existed since the release of VIMA 1.0 which was not considered an offiical release by VMware until vMA 4.0. The issue was with the use of vifpinit (now renamed to vifptarget) and when a target was initialized using the vi-fastpass library, the username and password was viewable in plain text.

When you add a target to vMA's management using vi-fastpass, two accounts are created on the target host: vi-adminXX and vi-userXX. The password for these two accounts are obfuscated using a simple XOR cipher which can be cracked in days if not hours and the obfuscated form is stored in a credential store located in /home/vi-admin/.vmware/credstore. Prior to vMA 4.1, when you initialize a target from this credential store, you are allowed to execute any vCLI or vSphere SDK for Perl script without having to provide additional credentials to the host. The authentication is basically bypassed as it uses the vi-adminXX credentials to login and perform the operation. The side effect of initializing the fastpass target, was that the password to the vi-adminXX was exposed as plain text via an environmental variable.

Here is an example of of initializing a target on vMA 4.0 with the password exposed:

As you can see from above, both the username and password is exposed as a simple environmental variable entry. You can now take those credentials and login to an ESX(i) host and perform an administrative operation as if you were root.

Here is an example of using these credentials to create a new vSwitch on an ESX host:

Before you jump and upgrade vMA 4.1, note that the security issue has been resolved but it does NOT make the system any more secure than it was in vMA 4.0. The vi-fastpass is actually available as a library module that supports both Perl and Java. There is available sample code under /opt/vmware/vima/samples/ for vMA4.0 and /opt/vmware/vma/samples/ for vMA 4.1. Using this library, you can access the targets under vMA management which also includes both the username and password in its unencrypted form.

Here is a vMA 4.0 script I wrote called enumeratevifp40.pl that demonstrates the above:

Here is a vMA 4.1 script I wrote called enumeratevifp41.pl that demonstrates the above:

As you can see, even with the security issue fixed vMA 4.1, a user can still access the entire credential store and obtain both the username and password to any of the targets. The only real way to protect against this issue is to use adauth when adding your targets and forcing users to authenticate against your AD server when connecting and performing an operation on vCenter or an ESX(i) host. For those that must use standard fpauth, VMware has released a KB1017669 article for vMA 4.1 on securing the credential store by creating an encrypted volume in which the obfuscated file is stored in. This ensures that if you are transferring your vMA image, someone can not just mount the VMDK and extract the credential store file and try to decrypt the contents.

Now, that you understand the security implication and features available with vMA 4.1, off you go to upgrade 🙂

Here are additional links that may also be useful:

  • http://www.virtuallyghetto.com/2010/07/resxtop-vi-fastpass-downgraded-feature.html
  • http://www.virtuallyghetto.com/2010/07/vma-41-active-directory-intergration.html

Categories // Uncategorized Tags // vma, vSphere 4.1

vMA 4.1 - Authentication Policy (fpauth vs adauth)

07.21.2010 by William Lam // 5 Comments

I recently wrote an article about vMA 4.1 and Active Directory Integration and today I noticed there were some confusion on the expected behavior of the two types of authentication policy: vi-fastpass authentication versus Active Directory authentication. There are actually a few things to consider:

  • What user context are you trying to execute a command against a target?
  • What authentication policy was used to add the target to vMA?
  • Is vMA host joined to an Active Directory Domain?
USER CONTEXT FPAUTH or ADAUTH vMA in AD DOMAIN
vi-admin fpauth no
DOMAIN\username adauth yes

I will try to explain the following two scenarios listed above.

In this example, vMA was not joined to an Active Directory Domain and we are adding a vCenter target to vMA using a local administrator account on vCenter server (by default, fpauth is assumed):

[vi-admin@tancredi ~]$ sudo vifp addserver manaslu.primp-industries.com
Enter username for manaslu.primp-industries.com: administrator
*protected email*'s password:
This will store username and password in credential store which is a security risk. Do you want to continue?(yes/no): yes

We can verify the target was added using fpauth by running the following command:

[vi-admin@tancredi ~]$ vifp listservers -l

esx4-1.primp-industries.com ESX fpauth
esxi4-3.primp-industries.com ESXi fpauth
manaslu.primp-industries.com vCenter fpauth

Next, we will set the fastpass target to the newly added vCenter server:

[vi-admin@tancredi ~]$ vifptarget -s manaslu.primp-industries.com

[vi-admin@tancredi ~][manaslu.primp-industries.com]$

If we run "esxcfg-nics -l" against an ESX(i) host that is being managed by this vCenter, we would do the following (note: user context is vi-admin):

[vi-admin@tancredi ~][manaslu.primp-industries.com]$ esxcfg-nics -l --vihost esxi4-3.primp-industries.com

Name PCI Driver Link Speed Duplex MAC Address MTU Description
vmnic0 02:00.0 e1000 Up 1000Mbps Full 00:50:56:ac:69:95 1500 Intel Corporation PRO/1000 MT Single Port Adapter

In this first example, we are relying solely on vi-fastpass authentication, where a vi-adminXX account is created on the target. The credentials to this account is generated by vMA and stored in the local credential store.

In this example, vMA has been joined to an Active Directory Domain and we are adding a vCenter target using Active Directory credentials:

[vi-admin@tancredi ~]$ sudo vifp addserver reflex.primp-industries.com --authpolicy adauth
Enter username for reflex.primp-industries.com: PRIMP-IND\primp

Note: As of writing this, there is a typo in vMA 4.1 documentation on the syntax to use when specifying the username when prompted. You will need to use DOMAIN\username, if you decide to use the --username, then you need to add a second "slash" to escape the first (e.g. DOMAIN\\username)

We can verify the target was added using adauth by running the following command:

[vi-admin@tancredi ~]$ vifp listservers -l

esx4-1.primp-industries.com ESX fpauth
esxi4-3.primp-industries.com ESXi fpauth
manaslu.primp-industries.com vCenter fpauth
reflex.primp-industries.com vCenter adauth

Next, we will set the fastpass target to the newly added vCenter server but before we do so, we need to login to vMA using a valid Active Directory account.

[primp@tancredi ~]$ vifptarget -s reflex.primp-industries.com

[primp@tancredi ~][reflex.primp-industries.com]$

Now if we run "esxcfg-nics -l" against an ESX(i) host that is being managed by this vCenter, we would do the following (note: user context is DOMAIN account):

[primp@tancredi ~][reflex.primp-industries.com]$ esxcfg-nics -l --vihost himalaya.primp-industries.com

Name PCI Driver Link Speed Duplex MAC Address MTU Description
vmnic0 06:00.0 e1000e Up 1000Mbps Full 00:30:48:d9:58:6a 1500 Intel Corporation 82574L Gigabit Network Connection
vmnic1 07:00.0 e1000e Down 0Mbps Half 00:30:48:d9:58:6b 1500 Intel Corporation 82574L Gigabit Network Connection

In this second example, we are relying solely on Active Directory authentication, where credentials of the user that is logged into vMA are being used. Unlike in the first example, if you were in the vi-admin context and tried to execute the same command, you will notice you are prompted for credentials. This is the intended and expected behavior of the two scenarios.

However, if you do not want to join vMA to an Active Directory Domain but would still like to perform an unattended authentication from vi-admin context, then you need to setup a Kerberos ticket for the target. The details on configuring this is outlined in vMA 4.1 user guide, please refer to the document for more details.

One thing to note which I actually ran into, is that when you join your vMA host to Active Directory Domain, you must reboot vMA after joining to the domain. If you do not, you will run into issues when trying to add a target using adauth authentication policy.

Categories // Uncategorized Tags // vi-fastpass, vifp, vma, vSphere 4.1

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William is Distinguished Platform Engineering Architect in the VMware Cloud Foundation (VCF) Division at Broadcom. His primary focus is helping customers and partners build, run and operate a modern Private Cloud using the VMware Cloud Foundation (VCF) platform.

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