PowerShell function to get the list of active connections, grouped or not

Get-NetstatProcess.ps1

<#
.SYNOPSIS
    It produces a list of the active connections and outputs to a file.
.DESCRIPTION
    The script basically calls the Get-NetTcpConnection cmdlet to have a picture of the active connections.
    Each connection is retrieved with all the details about the owning process.
    The $Grouped switch let you group the results and sort them descending by amount of active connections.
    The amount of free dynamic ports and the OS uptime are also printed.
.PARAMETER DESTINATIONFILEPATH
    String containing the output file path.
    Its existence will be checked.
.PARAMETER GROUPED
    Switch to define the results as simply listed or grouped.
.NOTES
    TODO: Check if the script is ran as administrator
.NOTES
    https://serverfault.com/questions/963140/what-are-sockets-with-bound-state-on-0-0-0-0
#>

function Get-NetstatProcess {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory=$True, HelpMessage="Output file destination path")]
        [ValidateScript({Test-Path $_ })]
        [string]$DestinationFilePath,
        [switch]$Grouped
    )

    # Variables
    $RightNow = Get-Date -Format "yyyyMMdd_HHmm"
    if ($Grouped) {
        $OutputFile = "$RightNow" + "_Netstat_grouped.log"
    } else {
        $OutputFile = "$RightNow" + "_Netstat_all_processes.log"
    }    

    # Date
    Get-Date -Format "dd-MM-yyyy HH:mm" | Out-file "$DestinationFilePath\$OutputFile" -Append 

    # Uptime
    $SinceLastBoot = (Get-Date) - (Get-CimInstance Win32_OperatingSystem).LastBootUptime
    $TotalTime = "Uptime : " + $SinceLastBoot.Days.ToString() + " days, " + $SinceLastBoot.Hours.ToString() + " hours"
    $TotalTime | Out-file "$DestinationFilePath\$OutputFile" -Append

    # Connections
    $Connections = Get-NetTCPConnection | Select-Object -property LocalAddress, LocalPort, RemoteAddress, RemotePort, State, @{Name = "PID"; Expression = { $_.OwningProcess } }, @{Name = "ProcessName"; Expression = { $(Get-Process -id $_.OwningProcess).Name } }, @{Name = "ProcessPath"; Expression = { $(Get-Process -id $_.OwningProcess).Path } }, @{Name = "HandleCount"; Expression = { $(Get-Process -id $_.OwningProcess).HandleCount } }

    # Format output
    if ($Grouped) {
        $GroupedConnections = $Connections | Group-Object -Property PID,State | Select-Object -Property Count,@{Name="State";Expression={($_.Name.Split(',')[1])}}, @{Name="ProcessID";Expression={($_.Name.Split(',')[0])}}, @{Name = "HandleCount"; Expression = { (Get-Process -PID ($_.Name.Split(',')[0].Trim(' '))).HandleCount } }, @{Name="ProcessName";Expression={(Get-Process -PID ($_.Name.Split(',')[0].Trim(' '))).Name}}, @{Name = "ProcessPath"; Expression = { (Get-Process -PID ($_.Name.Split(',')[0].Trim(' '))).Path } } 
        $GroupedConnections | Sort-Object Count -Descending | Format-Table -Property Count, State, ProcessID, ProcessName, @{ Expression='ProcessPath'; width = 255 }, HandleCount | Out-file "$DestinationFilePath\$OutputFile" -Append
        $OccupiedPorts = $GroupedConnections | Measure-Object -Property Count -Sum | Select-Object -ExpandProperty Sum
    
    } else {
        $Connections | Format-Table -Autosize -Property LocalAddress, LocalPort, RemoteAddress, RemotePort, State, PID, HandleCount, ProcessName, @{ Expression='ProcessPath'; width = 255 } | Out-file "$DestinationFilePath\$OutputFile" -Append
    }

    # Available ports
    $DynamicPorts = Get-NetTcpSetting | Select-Object -Property SettingName, @{Name="InitialPort"; Expression={$_.DynamicPortRangeStartPort}}, @{Name="AvailablePorts";Expression={$_.DynamicPortRangeNumberOfPorts}} | Where-Object {$_.SettingName -eq 'Internet'}
    $RemainingPorts = "Available dynamic ports: " + $($DynamicPorts.AvailablePorts - $OccupiedPorts)
    $RemainingPorts | Out-File "$DestinationFilePath\$OutputFile" -Append

}