Query for IP, loop back to query if IP already exists

[bvi1006]

Hi,

I've been trying to get the logic down to do the following:

Query for an IP

Ping the IP

If exists, query for IP again

If does not exist, continue on..

Can someone help me with this? I have worked on this, but I don't believe it's worth posting my code on this one!

Thanks in advance.

[LucD]

Are you testing the range of IP addresses in a subnet ?

WHat exactly do you mean with "query for an IP" ?

[bvi1006]

Hi Luc,

I'm just presenting a popup requesting an IP address from the user. I want to be sure the one they are giving me has not already been taken, so I want to ping the IP. If the ping succeeds I'd like to loop back and ask the user for another IP.

Thanks...

[LucD]

That can be done with the Test-Connection cmdlet.

Something like this for example

$ip = Read-Host "Enter IP address" 
while(Test-Connection -ComputerName $ip -Quiet -Count 1 -ErrorAction SilentlyContinue){
  "IP address $ip seems to be in use. try another IP address"
  $ip = Read-Host
}

[bvi1006]

Hi Luc,

The error message I get when running this is the following:

Testing connection to computer 'x.x.x.x' failed: Error due to lack of resources.

Resource unavailable.

This happens regardless of whether I input a good IP or not. Have you seen this message?

Thanks,

Jen

[LucD]

It seems something went wrong with my copy/paste of that code.

I corrected the code above. Can you try again ?

[gottr]

I have been using this solution for a while.  I query whole ranges since we use vlans but you should be able to modify for you use.  This snippet will ping IPs async and if a ping is recieved it will move on to the next IP.  If a ping is not recieved then it checks if there is a DNS entry (incase the server is off or rebooting).  Hope it helps!

#vlan125   
    if ($vlan -eq 'vlan125')
    {
    $valid = $true
   
        foreach($i in 254..3)
        {
        $ip = "111.111.1.$i"
            If (Test-Connection -comp $ip -count 1 -quiet)
            {
                write-host -ForegroundColor Green "Computer online $ip"
            }
            Else
            {
                "Computer offline $ip"
                try
                {
                    $HostName = [System.Net.Dns]::GetHostByAddress($ip).HostName
                    $hostname
                }
                catch
                {
                    write-host -ForegroundColor Red "This is the $ip that will be used.";
                    $valid=$false;
                    break
                }
            }
        }
            if ($valid -eq $true)
            {
            write-host -ForegroundColor Red "Alert there are no available IP address for $vlan"
            }
        $SUB = '255.255.255.0'
        $Gateway = '111.111.1.1'
    }

[bvi1006]

@Luc, no, still not working, I removed the onerror action and it worked.

[bvi1006]

@gottr - Thanks for the script - I am using Luc's script and will be adding the additional tests. Thanks again!

[LucD]

Strange, it works for me with the OnErrorAction parameter.

Are you using PowerShell v2 or v3 ?

[bvi1006]

2....

[LucD]

This is with PS v2.

Are you getting an error message ?

Can you include the message ?

[bvi1006]

Now I am not getting the error! I did get it earlier today, and yesterday:

[LucD · Accepted solution]

That error can appear when the Test-Connection fails to make a connection to the server or IP address.

That is the reason why I included the OnErrorAction.