subscriptions (over 100 sub) for that my college asked me if it is possible to write another script only to target one vnet or one subnet in a vnet ,and that’s normal since he does not need details about all the vnet’s that exist , and he need an updated version of the report since any change can happen and he can no be based on an older report .

for that I have added this two scripts below to help extract details about the vnet and subent and save the report in a stylish table format in excel .

How to Use :

1 – Connect to Azure: Run Connect-AzAccount to authenticate and connect to your Azure account.
2- Install-Module -Name ImportExcel -Scope CurrentUser -Force
3- Insert the subscription id ,the ressource group name ,the vnet ,and the subnet is optionel.
4 – Execute the Script: Copy and run the script in your PowerShell environment.
5 – View Results: The script outputs a summary to the console and saves detailed results to a specified Excel file.
6 – Access the Excel : Open the XlSX file located at path.xlxs` to review the details.

This script is useful for administrators needing to audit network configurations and IP usage across multiple Azure subscriptions.

Script:

$subscriptionId = ''
$resourceGroupName = ''
$vnetName = ''
$subnetName = ''  # Can be empty to process all subnets
$desktopPath = [System.Environment]::GetFolderPath("Desktop")
$exportDirectory = "$desktopPath\export_subnets"

Import-Module ImportExcel -Force

# Connect to Azure
Select-AzSubscription -SubscriptionId $subscriptionId

# Get the virtual network
$vnet = Get-AzVirtualNetwork -Name $vnetName -ResourceGroupName $resourceGroupName
if (-not $vnet) {
    Write-Host "The VNet $vnetName was not found." -ForegroundColor Red
    exit
}

# Function to process a single subnet
function Process-Subnet {
    param (
        [Parameter(Mandatory=$true)]
        $subnet
    )

    Write-Host "--------------------------"
    Write-Host " "
    Write-Host "   Subnet: $($subnet.Name)"
    $connectedDevices = $subnet.IpConfigurations.Count
    Write-Host "   Connected devices: $connectedDevices"

    # Calculate IPs
    $subnetMask = $subnet.AddressPrefix.Split('/')[1]
    $totalIps = [math]::Pow(2, 32 - $subnetMask)
    $reservedIps = 5
    $usedIps = $connectedDevices + $reservedIps
    $availableIps = $totalIps - $usedIps
    Write-Host "   Total IPs: $totalIps"
    Write-Host "   Used IPs: $usedIps"
    Write-Host "   Available IPs: $availableIps"

    # Service Endpoints and Delegations
    $serviceEndpoints = if ($subnet.ServiceEndpoints) { $subnet.ServiceEndpoints.Service -join ', ' } else { "None" }
    Write-Host "   Service Endpoints: $serviceEndpoints"
    $delegations = if ($subnet.Delegations) { $subnet.Delegations.ServiceName -join ', ' } else { "None" }
    Write-Host "   Delegations: $delegations"

    # Subnet address
    $addressPrefixString = $subnet.AddressPrefix -join ', '

    # Network interfaces
    $networkInterfaces = Get-AzNetworkInterface | Where-Object { $_.IpConfigurations.Subnet.Id -eq $subnet.Id }
    $results = @()

    foreach ($nic in $networkInterfaces) {
        foreach ($ipConfig in $nic.IpConfigurations) {
            $vm = Get-AzVM | Where-Object { $_.Id -eq $nic.VirtualMachine.Id }
            $vmName = if ($vm) { $vm.Name } else { "Not Available" }

            $results += [PSCustomObject]@{
                Subscription     = [string]$subscriptionId
                VNet            = [string]$vnetName
                Subnet          = [string]$subnet.Name
                AddressPrefix   = [string]$addressPrefixString
                TotalIps        = [int64]$totalIps
                UsedIps         = [int64]$usedIps
                AvailableIps    = [int64]$availableIps
                ConnectedDevices= [int]$connectedDevices
                ServiceEndpoints= [string]$serviceEndpoints
                Delegations     = [string]$delegations
                IpAddress       = [string]$ipConfig.PrivateIpAddress
                VMName          = [string]$vmName
                NicName         = [string]$nic.Name
                AttachedTo      = [string]"NIC: $($nic.Name), VM: $vmName"
            }
        }
    }

    # If no device found, add an empty row
    if ($results.Count -eq 0) {
        $results += [PSCustomObject]@{
            Subscription     = [string]$subscriptionId
            VNet            = [string]$vnetName
            Subnet          = [string]$subnet.Name
            AddressPrefix   = [string]$addressPrefixString
            TotalIPs        = [int64]$totalIps
            UsedIPs         = [int64]$usedIps
            AvailableIPs    = [int64]$availableIps
            ConnectedDevices= [int]0
            ServiceEndpoints= [string]$serviceEndpoints
            Delegations     = [string]$delegations
            IpAddress       = [string]""
            VMName          = [string]""
            NicName         = [string]""
            AttachedTo      = [string]"Not Applicable"
        }
    }

    return $results
}

# Determine which subnets to process
$subnetsToProcess = @()
if ([string]::IsNullOrEmpty($subnetName)) {
    $subnetsToProcess = $vnet.Subnets
    $exportFileName = "all_subnets.xlsx"
} else {
    $subnet = $vnet.Subnets | Where-Object { $_.Name -eq $subnetName }
    if (-not $subnet) {
        Write-Host "The subnet $subnetName was not found." -ForegroundColor Red
        exit
    }
    $subnetsToProcess = @($subnet)
    $exportFileName = "$subnetName.xlsx"
}

# Process all selected subnets
$allResults = @()
foreach ($subnet in $subnetsToProcess) {
    $results = Process-Subnet -subnet $subnet
    $allResults += $results
}

# Create export directory if it doesn't exist
if (-not (Test-Path -Path $exportDirectory)) {
    Write-Host "Creating export directory: $exportDirectory"
    New-Item -ItemType Directory -Path $exportDirectory | Out-Null
}

$excelFilePath = "$exportDirectory\$exportFileName"

try {
    $excelApp = New-Object -ComObject Excel.Application
    $excelApp.Visible = $false

    $workbook = $excelApp.Workbooks.Add()
    $worksheet = $workbook.Sheets.Item(1)
    $worksheet.Name = "Subnet Report"

    # Define headers with formatting
    $headers = @("Subscription", "VNet", "Subnet", "AddressPrefix", "TotalIPs", "UsedIPs", "AvailableIPs", 
                "ConnectedDevices", "ServiceEndpoints", "Delegations", "IpAddress", "VMName", "NicName", "AttachedTo")

    for ($i = 0; $i -lt $headers.Count; $i++) {
        $cell = $worksheet.Cells.Item(1, $i + 1)
        $cell.Value = $headers[$i]
        $cell.Font.Bold = $true
        $cell.Interior.ColorIndex = 37
        $cell.Borders.LineStyle = 1
    }

    # Insert data with borders
    $row = 2
    foreach ($result in $allResults) {
        for ($col = 1; $col -le $headers.Count; $col++) {
            $cell = $worksheet.Cells.Item($row, $col)
            $propertyName = $headers[$col - 1]
            $propertyValue = $result.$propertyName
            
            # Convert numeric values to strings for Excel
            if ($propertyValue -is [int64] -or $propertyValue -is [int] -or $propertyValue -is [double]) {
                $cell.Value2 = [double]$propertyValue
            } else {
                $cell.Value2 = [string]$propertyValue
            }
            
            $cell.Borders.LineStyle = 1
        }
        $row++
    }

    # Auto-fit column widths
    $worksheet.Columns.AutoFit()

    # Save and close the Excel file
    $workbook.SaveAs($excelFilePath)
    $workbook.Close()
    $excelApp.Quit()

    Write-Host "✅ Export completed! File saved at: $excelFilePath" -ForegroundColor Green
    Invoke-Item -Path $excelFilePath
} catch {
    Write-Host "❌ An error occurred: $($_.Exception.Message)" -ForegroundColor Red
} finally {
    if ($excelApp) { [System.Runtime.Interopservices.Marshal]::ReleaseComObject($excelApp) }
}

Ps : This article was written in collaboration with my friend Malik .

How to Use :

1 – Connect to Azure: Run Connect-AzAccount to authenticate and connect to your Azure account.
2 – Execute the Script: Copy and run the script in your PowerShell environment.
3 – View Results: The script outputs a summary to the console and saves detailed results to a specified CSV file.
4 – Access the CSV: Open the CSV file located at path.csv` to review the details.

This script is useful for administrators needing to audit network configurations and IP usage across multiple Azure subscriptions.

#Connect-AzAccount
# Define the subscription name
$subs = Get-AzSubscription 
# Initialize an array to store the results
$results = @()
# Initialize location  to store the results
$csvFilePath = "insert your path here\data.csv"
foreach ($Sub in $subs) {
    Write-Host "***************************"
    Write-Host " "
    Write-Host "Subscription: $Sub"
    Write-Host " "
    Write-Host "***************************"
    Write-Host " "
    $Sub.Name 
    
    $SelectSub = Select-AzSubscription -SubscriptionName $Sub.Name


    # Get all virtual networks in the subscription
    $VNETs = Get-AzVirtualNetwork
    foreach ($VNET in $VNETs) {
        Write-Host "--------------------------"
        Write-Host " "
        Write-Host "   vNet: $($VNET.Name)"
        Write-Host "   AddressPrefixes: $($VNET.AddressSpace.AddressPrefixes -join ', ')"
        Write-Host " "

        # Get expanded virtual network details including subnets and IP configurations
        $vNetExpanded = Get-AzVirtualNetwork -Name $VNET.Name -ResourceGroupName $VNET.ResourceGroupName -ExpandResource 'subnets/ipConfigurations'

        foreach ($subnet in $vNetExpanded.Subnets) {
            Write-Host "       Subnet: $($subnet.Name)"
            $connectedDevices = $subnet.IpConfigurations.Count
            Write-Host "          Connected devices: $connectedDevices"

            # Calculate total, used, and available IPs in the subnet
            $subnetMask = $subnet.AddressPrefix.Split('/')[1]
            $totalIps = [math]::Pow(2, 32 - $subnetMask)
            $reservedIps = 5  # 5 IPs are reserved by Azure
            $usedIps = $connectedDevices + $reservedIps
            $availableIps = $totalIps - $usedIps
            Write-Host "          Total IPs: $totalIps"
            Write-Host "          Used IPs: $usedIps"
            Write-Host "          Available IPs: $availableIps"

            # Get activated Service Endpoints
            $serviceEndpoints = if ($subnet.ServiceEndpoints) { $subnet.ServiceEndpoints.Service -join ', ' } else { "None" }
            Write-Host "          Service Endpoints: $serviceEndpoints"

            # Get Delegations Service Names
            $delegations = if ($subnet.Delegations) { $subnet.Delegations.ServiceName -join ', ' } else { "None" }
            Write-Host "          Delegations: $delegations"

            # Join the address prefixes into a single string
            $addressPrefixString = $subnet.AddressPrefix -join ', '

            # Add information for each IP configuration in the subnet
            foreach ($ipConfig in $subnet.IpConfigurations) {
                Write-Host "            IP Address: $($ipConfig.PrivateIpAddress)"

                # Attempt to get the VM name associated with this IP configuration
                $nic = Get-AzNetworkInterface | Where-Object { $_.IpConfigurations.Id -eq $ipConfig.Id }
                if ($nic) {
                    $vm = Get-AzVM | Where-Object { $_.Id -eq $nic.VirtualMachine.Id }
                    $vmName = if ($vm) { $vm.Name } else { "Not Available" }

                    # Add the information to the results array
                    $results += [PSCustomObject]@{
                        Subscription      = $Sub
                        VNet              = $VNET.Name
                        Subnet            = $subnet.Name
                        AddressPrefix     = $addressPrefixString
                        TotalIps          = $totalIps
                        UsedIps           = $usedIps
                        AvailableIps      = $availableIps
                        ConnectedDevices  = $connectedDevices
                        ServiceEndpoints  = $serviceEndpoints
                        Delegations       = $delegations
                        IpAddress         = $ipConfig.PrivateIpAddress
                        VMName            = $vmName
                        NicName           = $nic.Name
                    }
                } else {
                    # Add the information to the results array
                    $results += [PSCustomObject]@{
                        Subscription      = $Sub
                        VNet              = $VNET.Name
                        Subnet            = $subnet.Name
                        AddressPrefix     = $addressPrefixString
                        TotalIps          = $totalIps
                        UsedIps           = $usedIps
                        AvailableIps      = $availableIps
                        ConnectedDevices  = $connectedDevices
                        ServiceEndpoints  = $serviceEndpoints
                        Delegations       = $delegations
                        IpAddress         = $ipConfig.PrivateIpAddress
                        VMName            = "Not Available"
                        NicName           = "Not Available"
                    }
                }
            }

            # If there are no IP configurations, add a record with "0" connected devices
            if ($connectedDevices -eq 0) {
                $results += [PSCustomObject]@{
                    Subscription      = $Sub
                    VNet              = $VNET.Name
                    Subnet            = $subnet.Name
                    AddressPrefix     = $addressPrefixString
                    TotalIps          = $totalIps
                    UsedIps           = $usedIps
                    AvailableIps      = $availableIps
                    ConnectedDevices  = 0
                    ServiceEndpoints  = $serviceEndpoints
                    Delegations       = $delegations
                    IpAddress         = ""
                    VMName            = ""
                    NicName           = ""
                }
            }

            Write-Host " "
        }
    }
    Write-Host "***************************"
}

# Display the results in a table format
$results | Format-Table -AutoSize

# Export the results to a CSV file

$results | Export-Csv -Path $csvFilePath -NoTypeInformation

# Output a message to indicate the script has finished
Write-Output "Script completed. Results have been saved to CSV files."

# Open the CSV file to show the results
Invoke-Item -Path $csvFilePath

Results (Fake Data Results ,as i can not share real data ^^' )

Source Code  : link