Enumerating TCP Connections

What I was looking for is a simple script to capture all new ("Established") connections.  This could use some improve since my code has some side-effects.  'Compare-object' subtracts the diff between two arrays: the reference set and the difference set. To run this I type this at a PS prompt:

• function Est_do {do {Established} while (1)}
  
• Est_do | out-file $pwd\Established.txt
  

function global:Established 

{

    Begin

    {

    $a = [System.Net.NetworkInformation.IPGlobalProperties]::GetIPGlobalProperties()

    }

    Process

    {

    if ($b -ne $null) {$last_b = $b}

    $b = $a.GetActiveTcpConnections()   | where{$_.State -eq "Established" }  

    if ($last_b -ne $null) 

        {$c = compare-object $last_b $b;

            if ($c.SideIndicator -eq "=>" ) {write $c.InputObject | ft -HideTableHeaders}       

        }

   $global:last_b = $b

      }

    End 

    {

    start-sleep -m 250

    }  

}

[Established.txt] :

Established 192.168.0.8:3419 209.85.147.83:80

Established 192.168.0.8:3420 74.125.19.191:80

Established 192.168.0.8:3422 74.125.19.191:80

...