Daily Archives: 10th August 2015

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Simple netcat-like TCP Server or client

This entry was posted in Powershell Engine and tagged firewall ncat netcat on 10th August 2015 by Dimitri

Need to have a process listening on some port to test your firewall rules? Instead of using a netcat or ncat, here’s a very simple Powershell implementation of this ncat/netcat feature:

Simple TCP Server

PowerShell

function Wait-OnPort ($port) { $endpoint = new-object System.Net.IPEndPoint ([ipaddress]::any, $port) $listener = new-object System.Net.Sockets.TcpListener $endpoint $listener.start() $listener.AcceptTcpClient() # wait until somebody connect $listener.stop() }

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function Wait-OnPort ($port) { $endpoint = new-object System.Net.IPEndPoint ([ipaddress]::any, $port) $listener = new-object System.Net.Sockets.TcpListener $endpoint $listener.start() $listener.AcceptTcpClient() # wait until somebody connect $listener.stop() }

If you need a TCP Client, the code is very straightforward:

Use of TcpClient

PowerShell

$t = New-Object System.Net.Sockets.TcpClient("servernameorIPAddress",port) #port is not open, you get an exception New-Object : Exception calling ".ctor" with "2" argument(s): "No connection could be made because the target machine actively refused it 10.254.212.81:666" At line:1 char:16 + $t = New-Object <<<< System.Net.Sockets.TcpClient("servernameorIPAddress",port) + CategoryInfo : InvalidOperation: (:) [New-Object], MethodInvocationException + FullyQualifiedErrorId : ConstructorInvokedThrowException,Microsoft.PowerShell.Commands.NewObjectCommand #port is open, you get nothing $t.Close()

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$t = New-Object System.Net.Sockets.TcpClient("servernameorIPAddress",port) #port is not open, you get an exception New-Object : Exception calling ".ctor" with "2" argument(s): "No connection could be made because the target machine actively refused it 10.254.212.81:666" At line:1 char:16 + $t = New-Object <<<<  System.Net.Sockets.TcpClient("servernameorIPAddress",port)     + CategoryInfo          : InvalidOperation: (:) [New-Object], MethodInvocationException     + FullyQualifiedErrorId : ConstructorInvokedThrowException,Microsoft.PowerShell.Commands.NewObjectCommand   #port is open, you get nothing $t.Close()

 

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