Host-serial.ps1

function Get-VMHostWSManInstance {
    param (
    [Parameter(Mandatory=$TRUE,HelpMessage="VMHosts to probe")]
    [VMware.VimAutomation.ViCore.Impl.V1.Inventory.VMHostImpl[]]
    $VMHost,

    [Parameter(Mandatory=$TRUE,HelpMessage="Class Name")]
    [string]
    $class,

    [switch]
    $ignoreCertFailures,

    [System.Management.Automation.PSCredential]
    $credential=$null
    )

    $omcBase = "http://schema.omc-project.org/wbem/wscim/1/cim-schema/2/"
    $dmtfBase = "http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/"
    $vmwareBase = "http://schemas.vmware.com/wbem/wscim/1/cim-schema/2/"

    if ($ignoreCertFailures) {
        $option = New-WSManSessionOption -SkipCACheck -SkipCNCheck -SkipRevocationCheck
    } else {
        $option = New-WSManSessionOption
    }
    foreach ($H in $VMHost) {
        if ($credential -eq $null) {
            $hView = $H | Get-View -property Value
            $ticket = $hView.AcquireCimServicesTicket()
            $password = convertto-securestring $ticket.SessionId -asplaintext -force
            $credential = new-object -typename System.Management.Automation.PSCredential -argumentlist $ticket.SessionId, $password
        }
        $uri = "https`://" + $h.Name + "/wsman"
        if ($class -cmatch "^CIM") {
            $baseUrl = $dmtfBase
        } elseif ($class -cmatch "^OMC") {
            $baseUrl = $omcBase
        } elseif ($class -cmatch "^VMware") {
            $baseUrl = $vmwareBase
        } else {
            throw "Unrecognized class"
        }
        Get-WSManInstance -Authentication basic -ConnectionURI $uri -Credential $credential -Enumerate -Port 443 -UseSSL -SessionOption $option -ResourceURI "$baseUrl/$class"
    }
}

Get-VMHost | ForEach-Object {
  $VMHost = $_
  $PhysicalPackage = Get-VMHostWSManInstance -VMHost $_ -class CIM_PhysicalPackage -ignoreCertFailures | Where-Object {$_.ElementName -eq "Chassis"}
  $Report = "" | Select-Object -Property VMHost,SerialNumber
  $Report.VMHost = $VMHost.Name
  $Report.SerialNumber = $PhysicalPackage.SerialNumber
  $Report
} | Export-Csv -NoTypeInformation -UseCulture -Path c:\EsxSerialNumbers.csv