vmware | Earl C. Ruby III

If you’re like me, you rarely ssh into your vCenter appliance as “root”. However, the time comes when you need to update vCenter, you run the “Pre-Update Checks” — and because you never log into the appliance — you get the message that your root password needs to be updated before you can install the update.

So… log into the vCenter Service Management Console (https://your-vcenter:5480), click Access and then Edit. Make sure that SSH Login, DCLI, Console CLI, and BASH access are all enabled. Set the BASH timeout to 15 minutes so it gets disabled automatically when you’re done.

Once you’ve done that, ssh to the appliance.

$ ssh root@vcenter.labs.earlruby.org

VMware vCenter Server 7.0.0.10700

Type: vCenter Server with an embedded Platform Services Controller

Received disconnect from 192.168.200.11 port 22:2: Too many authentication failures
Disconnected from 192.168.200.11 port 22

Did you get a “Received disconnect … Too many authentication failures” message? Don’t worry, no one is hacking into your vCenter, it’s just that you have more than one ssh key on your keyring and for some reason someone at VMware thought that it would be a great idea to set the vCenter ssh setting MaxAuthTries = 2. Your first ssh key counts as one try, your second ssh key counts as attempt number 2, and… you’re done. vCenter won’t let you log in.

To bypass public key authentication checks entirely use the -o PubkeyAuthentication=no parameter for ssh:

$ ssh -o PubkeyAuthentication=no root@vcenter.labs.earlruby.org

VMware vCenter Server 7.0.0.10700

Type: vCenter Server with an embedded Platform Services Controller

root@vcenter.labs.earlruby.org's password:
Connected to service

    * List APIs: "help api list"
    * List Plugins: "help pi list"
    * Launch BASH: "shell"

Command>

Now get to the bash shell by typing shell, then passwd to set the new password, and you can update the root password:

Command> shell
Shell access is granted to root
root@vcenter [ ~ ]# passwd
New password:
Retype new password:
passwd: password updated successfully
root@vcenter [ ~ ]# exit
Command> exit
Connection to vcenter.labs.earlruby.org closed.

Before you log out, run the Pre-Update Check again to verify that vCenter sees that the password has been updated. This time you should get the message “No issues found. Pre-update checks have passed.”

Hope you find this useful.

I spin up a lot of VMs using VMware Fusion. I generally keep “clean” generic copies of a few different distros and versions of Linux servers ready to go with my login, an sshd server, ssh keys, and basic settings that I use already set up. When I need to quickly test something manually — usually some new, multi-VM distributed container orchestration or database system — I just make as many copies of the server’s *.vmwarevm file as I need, fire up the VM copies on my laptop, test whatever I need to test, then shut them down. Eventually I delete the copies and recover the disk space.

Depending on where my laptop is running I’ll get a completely random IP address for the VM from the local DHCP server. I would log into the consoles, get the IPs, then log into the various VMs from a terminal. (Cut and paste just works a whole lot better on a terminal than on the VMware console.)

However, since the console screens are up, and I repeat this pattern several times a week, I figured why not save a step and make the ephemeral VMs just show me their IP address on their consoles without having to login, so I added an “on reboot” file called /etc/cron.d/welcome on the master image which updates the /etc/issue file.

/etc/cron.d/welcome looks like this:

@reboot root (/bin/hostname; /bin/uname -a; echo; if [ -x /sbin/ip ]; then /sbin/ip addr; else /sbin/ifconfig; fi) > /etc/issue

When a new VM boots, it writes the hostname, kernel info, and the ethernet config to the /etc/issue file. /etc/issue is displayed on the screen before the login prompt, so now I can just glance at the console, see the IP address, and ssh to the new VM.

Although you’d never want to do this on a production system, it works great for ephemeral, throw-away test VMs.

Hope you find this useful.

Earl C. Ruby III

Tag Archives: vmware

Quickly get IP addresses of new VMs