Automate SNMP configuration on multiple ESXi hosts

I have created a PowerCLI script that can be used for applying SNMP configuration on multiple ESXi hosts of a vSphere Cluster by replicating configuration from a reference ESXi host.

Leave a comment with your email address if you have a question and I will get back to you soon.

Enjoy the script 🙂

  1. <#
  2.   configure-snmp-on-esxi.ps1
  4.   Configure SNMP settings on multiple ESXi hosts using a reference host settings
  6.   .History.
  7.   2020/04/09 - 0.1 - Reza Rafiee - First version
  9.   .Variables.
  10.   $VC: vCenter Server
  11.   $targethosts: Target ESXi host cluster
  12.   (to apply on single ESXi host refer to line30)
  13.   $refesxhost : Reference ESXi host
  15. #>
  17. $VC="vCenter Server Name"
  18. $targethosts="Target cluster name"
  19. $refesxhost = "Reference ESXi host name"
  23. Connect-viserver $VCServer
  24. $refhost = get-vmhost $refesxhost
  25. $refesxcli = Get-EsxCli -VMhost $refhost -V2
  26. $snmp=$refesxcli.system.snmp.get.invoke()
  27. write-host "SNMP configuration on " $refesxhost," (Refernce Host): "
  28. $snmp
  30. $vmhosts = get-cluster -name $targethosts | get-vmhost
  31. <#If you want to apply the snmp config on a single host
  32.  then enter ESXi host name for $targethosts variable and
  33.  replace the above line with the below line:
  35.  $vmhosts = get-vmhost -name $targethosts
  37.  #>
  40. foreach ($vmhost in $vmhosts){
  42. $esxcli = Get-EsxCli -VMHost $vmhost -V2
  44. <#Reset SNMP settings to factory default on the target host prior to
  45. reconfigure SNMP settings on that host#>
  46. $snmpreset = $esxcli.system.snmp.set.CreateArgs()
  47. $snmpreset.reset = $true
  48. $esxcli.system.snmp.set.Invoke($snmpreset)
  50. write-host "SNMP settigs has been reset to default on $vmhost"
  51. #SNMP settings reset complete
  53. $esxcli = Get-EsxCli -VMHost $vmhost -V2
  54. $arguments = $esxcli.system.snmp.set.CreateArgs()
  56. #The below arguments (if statements) cannot be null hence we skip the null ones
  58. if ($snmp.communities -ne $null) {
  59. $arguments.communities = $snmp.communities
  60. }
  62. if ($snmp.engineid -ne "$null") {
  63. write-host "engineid is nt null"
  64. $arguments.engineid = $snmp.engineid
  65. }
  67. if ($snmp.targets -ne $null) {
  68. $arguments.targets = $snmp.targets
  69. }
  71. if ($snmp.users -ne $null) {
  72. $arguments.users = $snmp.users
  73. }
  75. if ($snmp.privacy -in ("none", "AES128")) {
  76. $arguments.privacy = $snmp.privacy
  77. }
  79. if ($snmp.remoteusers -ne $null) {
  80. $arguments.remoteusers = $snmp.remoteusers
  81. }
  83. if ($snmp.authentication -in ("none", "MD5", "SHA1")) {
  84. $arguments.authentication = $snmp.authentication
  85. }
  87. if ($snmp.v3targets -in ("none", "auth", "priv")) {
  88. $arguments.v3targets = $snmp.v3targets
  89. }
  91. $arguments.hwsrc = $snmp.hwsrc
  92. $arguments.largestorage = $snmp.largestorage
  93. $arguments.loglevel = $snmp.loglevel
  94. $arguments.notraps = $snmp.notraps
  95. $arguments.enable = $snmp.enable
  96. $arguments.port = $snmp.port
  97. $arguments.syscontact = $snmp.syscontact
  98. $arguments.syslocation = $snmp.syslocation
  100. $esxcli.system.snmp.set.Invoke($arguments)
  102. $newsnmp=$esxcli.system.snmp.get.Invoke()
  103. write-host "SNMP configuration on", $vmhost, ": "
  104. $newsnmp
  106. }

Connect vNIC on a VM to network using command line

Once upon a time I had an ESXi host in disconnected state and the management services were out of order and even restarting management services couldn’t help out to get it back to manageable state.

While the Host was partially manageable we had to connect a network interface of a VM to network but the only option was command line. The below commands did the job:

You will need to find the VM ID and the vNIC device ID as well using the below two commands:

vim-cmd vmsvc/getallvms | grep "VM_Name"
vim-cmd vmsvc/get.configuration "VM_ID"

Then you can run the below command to connect/disconnect the vNIC:

vim-cmd vmsvc/device.connection true|false


How to know if ESXi or Xen server is using UEFI or Legacy boot mode

There might be times that you need to know if the ESXi host boot mode is set to UEFI or Legacy and obviously one option is to reboot the host and check the boot mode from BIOS. But it requires a downtime and sometimes it’s not an option in critical production environment.

Here is a simple command in both ESXi and Xen server that you can run to identify the boot mode without rebooting the server:


to check boot type of esx run this command from putty SSH:

vsish -e get /hardware/firmwareType


to check boot type of a xen host check for the EFI folder under /sys/firmware/

open up the xen host console and run the check the contents of /sys/firmware folder by running the below commands:

cd /sys/firmware/

if it returns a folder labled EFI then it’s UEFI boot. Otherwise it’s Legacy.

Some useful tips for powering off VMs from ESXi Command Line

There might be occasions that you need to power off VMs from ESXi command line for some reason. knowing how to do it can save you time and effort from dealing with corrupted virtual disks and VMs. For instance an ESXi host loses all network connectivity due to a driver and firmware compatibility issue and you have to reboot the host but the VMs are still running with no network connectivity. In that case it will be safer if you gracefully shutdown the VMs and then put the host in maintenance mode and then reboot the ESXi host. Let’s see how to do it:

First of all you will need to grab Virtual Machines ID by running the below command:

vim-cmd vmsvc/getallvms

Below command returns the VM’s power state:

vim-cmd vmsvc/power.getstate VMID

Now you can try grcefully shutdown the VM. If the VM doesn’t respond to graceful shutdown in couple of minutes then you can forcefully power it off by the second command:

#For gracefull shutdown:
vim-cmd vmsvc/power.shutdown VMID
#For forcefully powering off the VM:
vim-cmd vmsvc/ VMID

The alternative way of doing the power off action is using ESXCLI command:

esxcli vms vm list
esxcli vms vm kill --type=[soft,hard,force] --world-id= WorldNumber

If neither of the above work then you will need to kill the VM process using below commands:

#find the VM World ID
esxcli vm process list

#Kill the VM process
esxcli vm process kill --type=[soft,hard,force] --world-id= WorldNumber

Note You can kill VM process using ps and kill commands similar to “esxcli vm process” if esxcli is not functioning.

Once you power off all you VMs then you can put the ESXi host in maintenance mode and power it off or reboot it using the following command:

#put the host in maintenance mode
esxcli system maintenanceMode set --enable true

#Power off the ESXi host
esxcli system shutdown [poweroff,reboot] --delay "seconds" --reason "description"

Compare Advanced Settings of two ESXi hosts

Of course you can use host profile templates to check compliance of ESXi host configuration against baseline configuration. But there might be some ad-hoc times that you need to compare Advanced Settings of two ESXi hosts and probably export a report out of it.

The below piece of PowerCLI code would be helpful for that purpose.

The credit for this code goes to Frederic Martin, the author of the code.

    This script will compare all advanced settings between 2 ESXi servers
    The script will compare each of all advanced settings between a source and a destination ESXi server and will display the difference
    Author     : Frederic Martin -
.PARAMETER hostSourceName 
   Name of the host used for source compare
.PARAMETER hostDestinationName 
   Name of the host used for destination compare
   This switch allows you to bypass some advanced settings thanks to variable named $excludedSettings
	C:\foo> .\Compare-AdvancedSettings.ps1 -hostSourceName -hostDestinationName
	Display all differences between advanced settings from host and host
	C:\foo> .\Compare-AdvancedSettings.ps1 -hostSourceName -hostDestinationName -short
	Display differences (without those in $excludedSettings) between advanced settings from host and host

param (

# Checking if source host exists
if (-Not ($hostSource = Get-VMHost $hostSourceName -ErrorAction SilentlyContinue)) {
	Write-Host -ForegroundColor Red "There is no source host available with name" $hostSourceName

# Checking if destination host exists
if (-Not ($hostDestination = Get-VMHost $hostDestinationName -ErrorAction SilentlyContinue)) {
	Write-Host -ForegroundColor Red "There is no destination host available with name" $hostDestinationName

$diffAdvancedSettings = @()
# Using hastable for easy and fast handle
$advancedSettingsSource = @{}
$advancedSettingsDestination = @{}
# You can filter unwanted advanced settings to be unchecked (regexp)
$excludedSettings = "ScratchConfig.CurrentScratchLocation|ScratchConfig.ConfiguredScratchLocation|Vpx.Vpxa.config.vpxa.|UserVars.ActiveDirectoryPreferredDomainControllers|Config.Defaults.cpuidMask|Mem.HostLocalSwapDir"

# Retrieving advanced settings
Get-AdvancedSetting -Entity $hostSource | %{$advancedSettingsSource.Add($_.Name,$_.Value)}
Get-AdvancedSetting -Entity $hostDestination | %{$advancedSettingsDestination.Add($_.Name,$_.Value)}

# Browsing advanced settings and check for mismatch
ForEach ($advancedSetting in $advancedSettingsSource.GetEnumerator()) {
	if ( ($short -And $advancedSetting.Name -notmatch $excludedSettings -And $advancedSetting.Value -ne $advancedSettingsDestination[$advancedSetting.Name]) -Or (-Not $short -And $advancedSetting.Value -ne $advancedSettingsDestination[$advancedSetting.Name]) ) {
		$line = "" | Select Settings, SourceValue, DestinationValue
		$line.Settings = $advancedSetting.Name
		$line.SourceValue = $advancedSetting.Value
		$line.DestinationValue = $advancedSettingsDestination[$advancedSetting.Name]
		$diffAdvancedSettings += $line

# Displaying results

PowerCLI code to Find a datastore by NAA ID

There are times that you have a NAA ID of a LUN and need to find the corresponding datastore.

The below PowerCLI code is quite helpful that you can use to run to quickly find which datastore is attached to the NAA ID:

get-datastore |
Where-Object { $ -eq “NAA_ID of the Datastore”}

It returns the matching datastore name similar to this one:

get-datastore | Where-Object { $
iskname -eq "naa.60060160f12335007e8600b99aeae211"}

Name                               FreeSpaceGB      CapacityGB
----                               -----------      ----------
DATASTORE_HIGH_0                       294.117       1,023.750

PowerCLI shortcode to find ESXi host using a Mac Address

There might be a situation that you need to look up an ESXi host with it’s Mac address especially when troubleshooting and tracing network connectivity issues.

Although you can use RVTools report to find the matching ESXi host but sometimes PowerCLI is just there and probably easier to run a single line code to grab the required information.

You can use the below single line PowerCLI to simply find which ESXi host owns the Mac address:

Get-VMHost | Get-VMHostNetworkAdapter | 
Where-Object {$_.Mac -eq "00:25:b5:01:00:1b"} | 
Select VMHost, Name, DeviceName, Mac

If there is an ESXi host in your vCenter environment that owns that Mac address then it will retrun the Hostname and the NIC name similar to the below:

VMHost                Name               Mac
------                ----               ---
ESXi01.mylab          vmnic9             00:25:b5:01:00:1b