How to Listen on Port in PowerShell

This tutorial demonstrates how to listen on a port in PowerShell.

PowerShell Listen on Port

Listening on a port can be achieved using PowerShell with step-by-step commands. We can initialize a listener using the [System.Net.Sockets.TcpListener]Port command in PowerShell.

Follow the steps below to listen on a port using PowerShell:

1. First, we need to open PowerShell as an Administrator. Search PowerShell in the Start menu, right-click on the PowerShell icon, then click Run as Administrator.

   The system may ask for permission; click Yes.

2. Create a PowerShell script in the next step. Run the following command:

   New-Item 'C:\Users\Sheeraz\DemoTCPServer.ps1' -type file
   

   The above command will create a PowerShell file named DemoTCPServer.ps1 in the path C:\Users\Sheeraz. See the output:

   	Directory: C:\Users\Sheeraz
   
   
   Mode                 LastWriteTime         Length Name
   ----                 -------------         ------ ----
   -a----         11/3/2022   4:02 PM              0 DemoTCPServer.ps1
   

3. Once the file is created, the next step is to edit the script. Run the following command:

   ise C:\Users\Sheeraz\DemoTCPServer.ps1
   

   The above command will edit the file DemoTCPServer.ps1 in PowerShell ISE.

4. We will follow a step-by-step process for the DemoTCPServer.ps1 script.

   • First, initialize the variables for the port, a text file, and the server banner.

   • Then, create an endpoint on the given port.

   • Now, create a TCP port with a listener using the New-Object System.Net.Sockets.TcpListener $DemoEndpoint command. This will help us to listen on a port.

   • Start the TCP port.

   • Allow the TCP port to accept the TCP client.

   • Create a stream of the TCP client.

   • Now, create a writer with the stream.

   • Use the banner to write the lines and flush the writer.

   • Now, create a Buffer to read the stream to listen on a port.

   • Use a loop to read each line of the stream.

   • We have performed the listening on the port and now dispose of the buffer, stream, and TCP client.

   • Finally, stop the TCP Port. Let’s implement these steps in the PowerShell script DemoTCPServer.ps1.

```powershell
$DemoPort = 8080
$DemoFile = 'C:\Users\Sheeraz\demo.txt'
$DemoBanner = "Connection: OK"

$DemoEndpoint = New-Object System.Net.IPEndPoint([IPAddress]::Any, $DemoPort)
$DemoTCPPort = New-Object System.Net.Sockets.TcpListener $DemoEndpoint
$DemoTCPPort.Start()
Write-Output "The TCP Port $DemoPort is Open Now"
$AcceptIngTcp = $DemoTCPPort.AcceptTcpClient()
$Stream = $AcceptIngTcp.GetStream()
$DemoWriter = New-Object System.IO.StreamWriter($Stream)
$DemoBanner | % {
    $DemoWriter.WriteLine($_)
    $DemoWriter.Flush()
}

while ($true) {
    $DemoBuffer = New-Object System.IO.StreamReader $Stream
    $DEMOLINE = $DemoBuffer.ReadLine()
    if ($DEMOLINE -eq "quit") {
        break
    }
    else {
        $DEMOLINE
        $DEMOLINE |  Out-File $DemoFile -Append
    }
}
$DemoBuffer.Dispose()
$Stream.Dispose()
$AcceptIngTcp.Dispose()
$DemoTCPPort.Stop()
Write-Output "The TCP Port $DemoPort is Closed"
```

5. Once the script is created, save it. Now its time to execute the script to create a TCP port with listen on port operation; run the following command:

   PowerShell.exe -ExecutionPolicy Bypass -File C:\Users\Sheeraz\DemoTCPServer.ps1
   

   The above command will now start a TCP port and listen on a port. The output for the command is below.

   The TCP Port 8080 is Open Now
   

6. To connect to the TCP port on a remote computer, run the following telnet command in cmd. First, make sure the telnet service is activated, which can be checked from Control Panel>Programs>Turn Windows features on or off.

   See the command:

   telnet 10.10.10.10 8080
   

7. We can also use a telnet client application like PuTTY, which can be downloaded from here. Don’t forget to select Other and Telnet in the connection type.

   See the screenshot below.

   

8. Insert the IP and port, then click Open.

   

9. Now, we can use this terminal to send data over a connection and listen on a port. For example:

   This is PowerShell Listen on Port Test
   

   

10. The above-sent data will be saved the in the file 'C:\Users\Sheeraz\demo.txt', which means listening on the port is performed.

    

11. Finally, to close the TCP connection, run the quit command.