PSTelnet.ps1

Test-Port -Source '127.0.0.1' -Destination '10.196.11.206','10.196.11.206','10.196.11.206','123.234.234.3' `
                      -Port 3389,20, 21 -Verbose | ft -AutoSize
                      #-Iterate | Export-Csv portstatus.csv -NoTypeInformation

#Test-PortConnectivity '127.0.0.1' 'dc1' 57766 -Protocol UDP -Iterate
#Test-PortConnectivity 'localhost' 'dc2' 51753 -Protocol UDP
#Test-PortConnectivity -Source $EUCAS -Destination $EUMBX -Port 135 -Iterate
#Test-PortConnectivity -Source 'localhost' -Destination '127.0.0.1' -Port 135 -Iterate -protocol TCP

Function Test-Port
{

[cmdletbinding()]
Param
(
    [Parameter(Position=0)] $Source = $(Hostname),
    [Parameter(Mandatory=$true,Position=1)] $Destination,
    [Parameter(Mandatory=$true,Position=2)]
    [ValidateScript({
                        If($_ -match "^[0-9]+$"){$True}
                        else{Throw "A port should be a numeric value, and $_ is not a valid number"}
    })] $Port,
    [Parameter(Position=3)][ValidateSet('TCP','UDP')] $Protocol = 'TCP',
    [Switch] $Iterate
)

Begin{}
Process
{
    # If $source is a localhost, invoke command is not required and we can test port, withhout credentials
    If($Source -like "127.*" -or $source -like "*$(hostname)*" -or $Source -like 'localhost')
    {
        Do
        {
            PSTelnet $Destination $Port $Protocol;
            Start-Sleep -Seconds 1   #Initiate sleep to slow down Continous telnet
    
        }While($Iterate)
       
    }
    Else  #Prompt for credentials when Source is not the local machine.
    {     
        Get-Credential -Message "Provide Admin credentials to Telnet from [Remote source] to [Remote destination] machine(s)" -OutVariable Credentials
        If($Credentials)
        {
            Do
            {
                Foreach($Item in $Source)
                {          
                    Invoke-command -ComputerName $Item `
                                   -Credential $Credentials `
                                   -ScriptBlock ${Function:PSTelnet} `
                                   -ArgumentList $Destination,$Port,$Protocol                                            
                }
    
                # Sleep to slow down Continous telnet
                Start-Sleep -Seconds 1

            }While($Iterate)
        }
       
    }

}
end{}

}
  
Function PSTelnet
{

[Alias("Tn")]
[Cmdletbinding()]
Param(
        [String[]] $Destination, 
        [Int[]] $port, 
        [string[]] $Protocol
)

Begin
{
    $Source = (hostname).toupper()    
}
Process
{
    Foreach($Target in $Destination)
    {
        Foreach($CurrentPort in $Port)
        {
            Write-Verbose "Testing $Protocol port $CurrentPort from $Source to $Target"

            $HostStatus = (QuickPing -Computername '127.0.0.1').status
            
            If($Protocol -eq 'TCP')
            {

                Try
                {
                    $TCPClient = New-Object System.Net.Sockets.TCPClient 
                    $Connection = $TCPClient.BeginConnect('127.0.0.1',20, $null, $null)
                    $wait = $Connection.AsyncWaitHandle.WaitOne(5000,$false)
                    $TCPClient.EndConnect($Connection) 

                    If($PortStatus)
                    {
                        #Write-host "$((hostname).toupper()) connected to $($Target.toupper()) on $Protocol port : $currentPort " -back green -ForegroundColor White
                        
                        ''|select @{n='Source';e={$Source}},`
                                  @{n='Destination';e={$Target.toupper()}},`
                                  @{n='Protocol';e={$Protocol}},`
                                  @{n='Port';e={$CurrentPort}},`
                                  @{n='Open';e={$true}}, `
                                  @{n='HostUp?';e={If($HostStatus -eq 'success'){$True}else{$false}}} 
                    }
                }
                Catch
                {
                    #Write-host "$((hostname).toupper()) Not connected to $($Target.toupper()) on $Protocol port : $currentPort" -back red -ForegroundColor white
                    
                    ''|select @{n='Source';e={$Source}},`
                              @{n='Destination';e={$Target.toupper()}},`
                              @{n='Protocol';e={$Protocol}},`
                              @{n='Port';e={$CurrentPort}},`
                              @{n='Open';e={$false}}, `
                              @{n='HostUp?';e={If($HostStatus -eq 'success'){$True}else{$false}}} 
                }
                Finally
                {
                    $TCPClient.Close()
                }            
            }
            Else
            {   
                                                              
                #Create object for connecting to port on computer   
                $UDPClient = new-Object system.Net.Sockets.Udpclient 
                
                #Set a timeout on receiving message, to avoid source machine to Listen forever. 
                $UDPClient.client.ReceiveTimeout = 5000 
                
                #Datagrams must be sent with Bytes, hence the text is converted into Bytes
                $ASCII = new-object system.text.asciiencoding
                $Bytes = $ASCII.GetBytes("Hi")
                
                #UDP datagram is send
                [void]$UDPClient.Send($Bytes,$Bytes.length,$Target,$Port)  
                $RemoteEndpoint = New-Object system.net.ipendpoint([system.net.ipaddress]::Any,0)  
                 
                Try
                {
                    #Waits for a UDP response until timeout defined above
                    $RCV_Bytes = $UDPClient.Receive([ref]$RemoteEndpoint)  
                    $RCV_Data = $ASCII.GetString($RCV_Bytes) 
                    If($RCV_Data) 
                    {
                   
                        #Write-host "$((hostname).toupper()) connected to $($Target.toupper()) on $Protocol port : $currentPort " -back green -ForegroundColor White
                        ''|select @{n='Source';e={$Source}},`
                                  @{n='Destination';e={$Target.toupper()}},`
                                  @{n='Protocol';e={$Protocol}},`
                                  @{n='Port';e={$CurrentPort}},`
                                  @{n='Open';e={$true}}, `
                                  @{n='HostUp?';e={If($HostStatus -eq 'success'){$True}else{$false}}} 
                    }
                }
                catch
                {
                    #If the UDP recieve is timed out it's inferred that no response was received.
                    #Write-host "$((hostname).toupper()) Not connected to $($Target.toupper()) on $Protocol port : $currentPort " -back red -ForegroundColor White
                    ''|select @{n='Source';e={$Source}},`
                              @{n='Destination';e={$Target.toupper()}},`
                              @{n='Protocol';e={$Protocol}},`
                              @{n='Port';e={$CurrentPort}},`
                              @{n='Open';e={$false}}, `
                              @{n='HostUp?';e={If($HostStatus -eq 'success'){$True}else{$false}}} 
                }
                Finally
                {l
                
                    #Disposing Variables
                    $UDPClient.Close()
                    $RCV_Data=$RCV_Bytes=$null
                }                                    
            }

        }
    }
}
end{}

}

# Though we have Test-Connection cmdlet, but that don't have a Timeout option in it. 
# Which makes running the script for multiple machines somewhat slower, as it waits for default timeout
# As a workaround, instantiating System.Net class give us an option to specify the TimeOut for ICMP requests, hence this function
Function QuickPing
{
    Param(
            [String] $Computername
    )
    
    [int]$timeout = 80
    [switch]$resolve = $true
    [int]$TTL = 128
    [switch]$DontFragment = $false
    [int]$buffersize = 32
    $options = new-object system.net.networkinformation.pingoptions
    $options.TTL = $TTL
    $options.DontFragment = $DontFragment
    $buffer=([system.text.encoding]::ASCII).getbytes("hi"*$buffersize)
    $Ping = New-Object system.net.networkinformation.ping
    $ping.Send($Computername,$timeout,$buffer,$options)
    $ping.Dispose()
}