Reservce dynamic tcp udp port.

 

Show excluded port range:

netsh int ipv4 show excludedportrange tcp




Reserve port:

netsh int ipv4 add excludedportrange protocol=tcp startport=49698 numberofports=1




netsh int ipv6 add excludedportrange protocol=udp startport=63566 numberofports=5

 

How to test if a port is open using powershell

Use this Powershell command to to test if a port is open on a server and if you are able to connect to it remotely.

$tcp = New-Object System.Net.Sockets.TcpClient
$tcp.connect('servername or ip address', portnumber)

Or you can use this single line of code
(New-Object System.Net.Sockets.TcpClient).Connect('servername or ip address', portnumber)

There is also an in built powershell cmdlet that lets you test a port connection which only works with powershell 4.0

Test-NetConnection -Port portnumber -Computername 'Servername or ip address'

The first commands are much faster compared to the second one but does not give you any output.
The powershell cmdlet does give you a good output that you can use in another script but is much slower.