Powershell looping Test-NetConnection

Question

I'm a bit new to Powershell scripting and I'm trying to create a simple loop with the Test-NetConnection tool, but I don't know how to do this.

This is what I have:

param(
  [string]$tcpserveraddress,
  [string]$tcpport
)
if (Test-NetConnection -ComputerName $tcpserveraddress -Port $tcpport -InformationLevel Quiet -WarningAction SilentlyContinue) {"Port $tcpport is open" }
else {"Port $tcpport is closed"}

If the tcpport is not open, I would like the script to loop and issue the text "Port $tcpport is closed" every 10 seconds, until it is open.
When tcppport is open, it should display the "Port $tcpport is open" text and terminate.

`while( ! (Test-NetConnection ...)) {"Port $tcpport is closed"; Start-Sleep 10}` — zett42, Mar 28 '22 at 13:53
Hi zett42, Thank you very much for your fast help. This is working great! — Eric van Loon, Mar 28 '22 at 14:39

codewario · Accepted Answer · 2022-03-28T15:14:06.260

We can use a while loop to achieve this with a few modifications to your existing code:

param(
  [string]$tcpserveraddress,
  [string]$tcpport
)

$tcnArgs = @{
  ComputerName = $tcpserveraddress
  Port = $tcpport
  WarningAction = 'SilentlyContinue'
}

while( !( Test-NetConnection @tcnArgs ).TcpTestSucceeded ) {
  "Port $tcpport is closed"
  Start-Sleep -Seconds 60
}

"Port $tcpport is open"

Since you indicated you are new to PowerShell, here's a breakdown of how this works:

For the sake of readability, I have use argument splatting to define and pass the cmdlet parameters as a hashmap. Here are some additional answers that explain splatting in more detail, for those interested.
No longer use -InformationLevel Quiet. In a script we generally want the detailed object as it has more information on it, and we can operate off of its properties.
The while loops, until ( Test-NetConnection @tcnArgs ).TcpTestSucceeded returns true. In other words, the loop code runs while the TCP test is failing.
Sleep in the loop, no need to check constantly.
Once the while loop exits, output a string stating the TCP port is open

Powershell looping Test-NetConnection

1 Answers1