Question

I currently have a script that listens on a specified port. I would like this script to stop running after 5 seconds, regardless of getting connected to or not. Is there a way that I am able to do that? Some sort of delay

function listen-port ($port) {
    $endpoint = new-object System.Net.IPEndPoint ([ipaddress]::any,$port)
    $listener = new-object System.Net.Sockets.TcpListener $endpoint
    $listener.start()
    $listener.AcceptTcpClient() # will block here until connection
    $listener.stop()
    }
listen-port 25

Answer 1

If you are not going to do anything with the client, then you don’t have to accept them and can just stop listening:

function listen-port ($port) {
$endpoint = new-object System.Net.IPEndPoint ([ipaddress]::any,$port)
$listener = new-object System.Net.Sockets.TcpListener $endpoint
$listener.start()
Start-Sleep -s 5
$listener.stop()
}

You can utilize the asynchronous AcceptTcpClient methods (BeginAcceptTcpClient,EndAcceptTcpClient) if you need to do something with the client:

function listen-port ($port) {
$endpoint = new-object System.Net.IPEndPoint ([ipaddress]::any,$port)
$listener = new-object System.Net.Sockets.TcpListener $endpoint
$listener.start()
$ar = $listener.BeginAcceptTcpClient($null,$null) # will not block here until connection

if ($ar.AsyncWaitHandle.WaitOne([timespan]'0:0:5') -eq $false) 
{ 
 Write-Host "no connection within 5 seconds" 
}
else
{ 
 Write-Host "connection within 5 seconds"
 $client = $listener.EndAcceptTcpClient($ar)
}

$listener.stop()
}

Another option would be to use the Pending method on the listener:

function listen-port ($port) {
$endpoint = new-object System.Net.IPEndPoint ([ipaddress]::any,$port)
$listener = new-object System.Net.Sockets.TcpListener $endpoint
$listener.start()
Start-Sleep -s 5

if ($listener.Pending() -eq $false)
{
 Write-Host "nobody connected"
} 
else
{ 
 Write-Host "somebody connected"
 $client = $listener.AcceptTcpClient()
}

$listener.stop()
}