Opening up a port with powershell

Question

On Machine A I am running a port scanner. On Machine B I would like to open and close ports in an organized fashion. I am hoping to do all of this

Answer 1

Avoid COM if possible. You can use TcpListener to open a port:

$Listener = [System.Net.Sockets.TcpListener]9999;
$Listener.Start();
#wait, try connect from another PC etc.
$Listener.Stop();

If you happen to miss a Stop command during debugging - just close and re-open the application from where you opened the socket - hanging port should be cleared. In my case it was PowerGUI script editor.

Then use TcpClient to check it.

(new-object Net.Sockets.TcpClient).Connect($host, $port)

If you cannot connect, means the firewall is blocking it.

EDIT: To print a message when connection is received, you should be able to use this code (based on this article from MSDN):

#put this code in between Start and Stop calls.
while($true) 
{
    $client = $Listener.AcceptTcpClient();
    Write-Host "Connected!";
    $client.Close();
}