Can I check for specific HTTP response codes with PRTG?

There is no native Sensor within PRTG which can do this but you may use the following script in addition to a EXE/Script Sensor:

sUrl = "http://www.google.com"
sStatusToCheck = 200


If Wscript.Arguments.Count = 1 then
    sUrl = Wscript.Arguments(0)
End If

If Wscript.Arguments.Count = 2 then
    sUrl = Wscript.Arguments(0)
    sStatusToCheck = Wscript.Arguments(1)
End If

Set oXMLHTTP = CreateObject("MSXML2.XMLHTTP.3.0")

oXMLHTTP.Open "GET", sUrl, False, " "," "
oXMLHTTP.Send

WScript.Echo oXMLHTTP.Status & ":" & oXMLHTTP.StatusText

If oXMLHTTP.Status = sStatusToCheck then
    WScript.Quit("0")
Else
    WScript.Quit("2")
End If

The script can be called with parameters, where the first parameter has to be the URL and the second parameter has to be the Status Code to check for (e.g. 200,401,...).

Kudos for the script go to PRTG User Colby.

Nice script! Thnx! I extended it a bit, by disabling redirects, adding post values and extending error handling:

'************************************************
'**  Init
'************************************************
Option Explicit
Dim oXMLHTTP
Dim url, postParameter
Const WinHttpRequestOption_EnableRedirects = 6

'************************************************
'**  Configuration parameters
'************************************************
url				= "http://www.google.com"
postParameter	= ""

'************************************************
'**  Main
'************************************************
If Wscript.Arguments.Count = 1 then
    url				= Wscript.Arguments(0)
ElseIf Wscript.Arguments.Count = 2 then
    url				= Wscript.Arguments(0)
    postParameter	= Wscript.Arguments(1)
End If

Set oXMLHTTP = CreateObject("WinHttp.WinHttpRequest.5.1")

oXMLHTTP.Option(WinHttpRequestOption_EnableRedirects)	= false
oXMLHTTP.Open "POST", url, False
oXMLHTTP.Send postParameter

'************************************************
'**  Return value
'************************************************
If Err.Number = 0 Then
	WScript.Echo oXMLHTTP.Status & ":" & oXMLHTTP.StatusText
	WScript.Quit(0)
Else
	WScript.Quit(2)
End If

Here is an updated version, I believe there was a bug with Konstantin's version: when sStatusToCheck is given as argument, it is cast as string, not int, so the status part of the script should be:

[...] If oXMLHTTP.Status = CInt(sStatusToCheck) then [...]

Here is a revised version (note: http only, https support should be fairly easy, or duplicate the check):

'******************************************************************************
'** Script to check a specific HTTP return code
'** 
'** Authors: PRTG User Colby, Konstantin Wolff (Paessler Support), Thomas Blanchard - [email protected]
'** Version: 0.01
'** Version Date: 2014-12-03
'** Source: 
'** 	- https://kb.paessler.com/en/topic/47373-can-i-check-for-specific-http-response-codes-with-prtg
'******************************************************************************

sHost = "www.lynda.com"
sStatusToCheck = 200

If Wscript.Arguments.Count = 1 then
    sHost = Wscript.Arguments(0)
End If

If Wscript.Arguments.Count = 2 then
    sHost = Wscript.Arguments(0)
    sStatusToCheck = Wscript.Arguments(1)
End If

sUrl = "http://" & sHost & "/"
' WScript.Echo sUrl & " " & sStatusToCheck

Set oXMLHTTP = CreateObject("MSXML2.XMLHTTP.3.0")

oXMLHTTP.Open "GET", sUrl, False, " "," "
oXMLHTTP.Send

sMsg = sHost & " returns " & oXMLHTTP.Status & " " & oXMLHTTP.StatusText & " (expecting " & sStatusToCheck & ")"

If oXMLHTTP.Status = CInt(sStatusToCheck) then
	WScript.Echo oXMLHTTP.Status & ":OK " & sMsg
    WScript.Quit("0")
Else
	WScript.Echo oXMLHTTP.Status & ":ERROR " & sMsg
    WScript.Quit("2")
End If

Can you please post how should parameters be typed for different url and status code? I can not get it work with parameters.

Hi Ozgur,

You can also try the following PowerShell script: http://pastebin.com/KpCSbrzt

Call it with the following parameters:
-URL "www.google.de" -ResponseCode 220 -Protocol "HTTP"

Note Remember to execute a PowerShell (x86) with admin privileges and run Set-ExecutionPolicy RemoteSigned

...in order to make the script work :)

Hello,

I am currently running the Powershell script that Stephan posted, and the script itself is running correctly (from what I can tell). PRTG, however, is not picking up on the value that the script is putting out, and I am getting "Unauthorized access" as the last message. Any thoughts?

What URL are you trying to check?

https://mobile.processnow.com

Stephan,

I modified your version of the Powershell script (see below) so that I am able to successfully get response codes in our environment. PRTG is giving me an "Unauthorized Access" error when I tell the EXE/Script Sensor to run it. Any thoughts?

param(
    [string]$URL,
    [int]$ResponseCode1 = "",
    [int]$ResponseCode2 = "200",
    [string]$DefaultDNS = "false",
    [string]$protocol = "https",
    [string]$HeaderHost = "https://mobile.processnow.com"
    ) 
 
# Ignore SSL errors
[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}
 
$URL = $HeaderHost
$req = [system.Net.WebRequest]::Create($URL)


       
 
# Add some headers to the web request (for round robin dns and load balancers)
#$req.$Host = $HeaderHost;
$req.AllowAutoRedirect=$true
# catch exceptions
try                                                     { $res = $req.GetResponse() }
catch [System.Net.WebException] { $res = $_.Exception.Response }
 
 
# get the numeric response code of the request
$ResponseCode1 = (($res.StatusCode) -as [int])
 
# and some error handling
if([int]$ResponseCode1 -eq [int]$ResponseCode2){
    Write-Host $ResponseCode2":Page returned HTTP code "$ResponseCode1" as expected (used "$URL").";
    exit 0;
}
 
elseif([int]$ResponseCode1 -eq 200){
        Write-Host $ResponseCode1":Connection error (used "$URL").";
}
 
else{
    Write-Host $ResponseCode1":Page returned "$ResponseCode1" instead of $ResponseCode2 unexpectedly (used "$URL").";
}

Can you post your sensor settings? You probably have to set "Use security context of parent device" in the sensor security context settings. Can you check that?

I have set the security settings to "Use security context of parent device." I am still getting Unauthorized Access, however I am showing that the value is 0. According to the manual, the #0 indicates that the script is running ok. Right?

Are you using a proxy server by any chance? What's the output of the script when run in PowerShell?

We do have proxies setup between the two locations.

When I run the script manually in Powershell, the output is this:

200:Page returned HTTP code 200 as expected (used https://register.processnow.com).

Is the proxy server configured via GPO? Or via IE? Can you try a different windows user in the parent device credential settings? Probably your own user account?

Hello,

How does it work with https? I have some Login-Sites which i can monitor with this script. I can open them with http and https. on one of the Server,only https is active an the other Servers will follow in time. on the Server with only https i get "Query Failed: Unable to connect to the server", wehne I use the "best Answer" script.

I really need help to monitor the https login

Hi there,

PowerShell is rather picky with its TLS connections. Kindly use the updated version in the best answer, I modified it to support self-signed certificates :)

Kind regards,
Stephan Linke, Tech Support Team

Hi, thank your for providing this script. I have a problem with the script and Windows Server 2019. I get following error when starting it with prtg: This version of %1 is not compatible with the version of Windows you're running. Check your computer's system information and then contact the software publisher. (0xD8)

Does anybody know what to change to make it work?

Thank you in advance

What do your parameters look like and did you check our guide regarding custom PowerShell based Sensors?

Is the URL available without any authentication? And is that the actual URL? What error do you get?

I´ve found the issue. I had the wrong file extension (not .ps1)

@ Luciano Lingnau,

I've tried using the latest script posted but having an error on PRTG. Any thoughts?

Below is the error though i can ran the script successfully on a device.

Sensor Custom EXE/Script Sensor Response not well-formed: "(add-type : (0) : Source file 'C:\windows\TEMP\205ir4ea.0.cs' could not be found (1) : using System.Net; At C:\Program Files (x86)\PRTG Network Monitor\custom sensors\EXE\2_EPHD_URL_Response_Code.ps1:6 char:1 + add-type @" + ~~~~~~~~~~~ + CategoryInfo : InvalidData: (error CS2001: S...ld not be found: CompilerError) [Add-Type], Exception + FullyQualifiedErrorId : SOURCE_CODE_ERROR,Microsoft.PowerShell.Commands. AddTypeCommand add-type : (0) : No source files specified (1) : using System.Net; At C:\Program Files (x86)\PRTG Network Monitor\custom sensors\EXE\2_EPHD_URL_Response_Code.ps1:6 char:1 + add-type @" + ~~~~~~~~~~~ + CategoryInfo : InvalidData: (warning CS2008:...files specified: CompilerError) [Add-Type], Exception + FullyQualifiedErrorId : SOURCE_CODE_ERROR,Microsoft.PowerShell.Commands. AddTypeCommand add-type : Cannot add type. Compilation errors occurred. At C:\Program Files (x86)\PRTG Network Monitor\custom sensors\EXE\2_EPHD_URL_Response_Code.ps1:6 char:1 + add-type @" + ~~~~~~~~~~~ + CategoryInfo : InvalidData: (:) [Add-Type], InvalidOperationExc eption + FullyQualifiedErrorId : COMPILER_ERRORS,Microsoft.PowerShell.Commands.Ad dTypeCommand <prtg> <result> <channel>Status Code</channel> <value>401</value> <valuelookup>prtg.standardlookups.http.statuscodedetailed_401</valuelookup> </result> <result> <channel>Length</channel> <value>-1</value> </result> <result> <channel>ExecTime</channel> <value>58</value> <CustomUnit>msecs</CustomUnit> </result> <text>https://phd.onefluor.com/#/login</text> </prtg> )" (code: PE132)

What's the output of $PSVersiontable (in PowerShell)?

@Luciano Lingnau thank you for the script it worked very good in my own environment, when I moved the script to the company it did not want to connect to the url because of ssl connection, so I had to add two more lines to the code for it to work ( even adding -TrustAllCerts did not do the trick ).

$AllProtocols = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12' [System.Net.ServicePointManager]::SecurityProtocol = $AllProtocols [System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy

so the final product is:

param(
	[Parameter(Mandatory=$true)]
	[string]$Url,
	[int]$Timeout = "30",
	[switch]$TrustAllCerts = $false
)

[string]$sensorMessage = ''
$errorFlag = $false
$results = @()

#Avoid issues with weird SSL Certificates (Self-signed, expired, etc)
#Should only be used when a trusted certificate is not an option
if ($TrustAllCerts){
add-type @"
using System.Net;
using System.Security.Cryptography.X509Certificates;
public class TrustAllCertsPolicy : ICertificatePolicy {
    public bool CheckValidationResult(
        ServicePoint srvPoint, X509Certificate certificate,
        WebRequest request, int certificateProblem) {
        return true;
    }
}
"@
$AllProtocols = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12'
[System.Net.ServicePointManager]::SecurityProtocol = $AllProtocols
[System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy
}

try {
	#Stopwatch used to time the lenghtiest part of the execution (long execution times could be an issue)
	$exectime = [System.Diagnostics.Stopwatch]::StartNew()

	$a = Invoke-WebRequest  -UseBasicParsing -Uri $Url -TimeoutSec $Timeout -ErrorAction SilentlyContinue

	#Stop Stopwatch used to time the lenghtiest part of the execution
	$exectime.Stop()

	#Parse the results in a PRTG Friendly way
	if ($a.StatusCode){
		$results += @{
			Channel = 'Status Code'
			Value = $a.StatusCode
			valuelookup = 'prtg.standardlookups.http.statuscode'
		}
		$results += @{
			Channel = 'Execution Time'
			Value = $exectime.ElapsedMilliseconds
			Unit = 'TimeResponse'
		}
	}

    $sensorMessage = "$($url)"

} catch {

	#If there is a valid statuscode in the response (like 3XX) we want that to be a sensor result, so this has to be handled in the try/catch

    if ($_.Exception.Response.StatusCode.Value__ -gt 0){

		#Parse the results in a PRTG Friendly way
		$results += @{
			Channel = 'Status Code'
			Value = $_.Exception.Response.StatusCode.Value__
			valuelookup = 'prtg.standardlookups.http.statuscode'
		}
		$results += @{
			Channel = 'Execution Time'
			Value = $exectime.ElapsedMilliseconds
			Unit = 'TimeResponse'
		}
		
		$sensorMessage = "$($url)"

	}else{

		#Otherwise it's an exception that doesn't have a valid result

		$errorFlag  = $true
		$sensorMessage = "Exception (Line $($_.InvocationInfo.ScriptLineNumber)): $($_.Exception.Message)"
	}

}

$sensorResult = '' | Select-Object prtg
if ($errorFlag) {
	$sensorResult.prtg = '' | Select-Object error
	$sensorResult.prtg.error = 1
} else {
	$sensorResult.prtg = '' | Select-Object result
	$sensorResult.prtg.result = $results
}
if ($sensorMessage) {
	$sensorResult.prtg | Add-Member -MemberType NoteProperty -Name 'text' -Value $null
	$sensorResult.prtg.text = $sensorMessage
}
$sensorResult | ConvertTo-Json -Depth 5 | Write-Output

P.S: I did not understood the need for the Lenght result so I deleted it. I am using theprtg.standardlookups.http.statuscodedetailed lookup and it does wonders, thank you lots!

Hello L3ca,
thank you for your reply and kind feedback!

From what I've seen recently, different powershell versions and host operating systems will have their own nitpicks with SSL endpoints in powershell. I will consider updating the default script to include the code you've suggested :)

And as for the "Length" channel, I've included it because there are probably cases where this is relevant. And because the HTTP Advanced sensor also includes this channel by default(Length). And this sensor is meant as a custom alternative to the HTTP Advanced sensor.

But either way, I'm really happy to hear the code/sensor was helpful to you.

Best Regards,
Luciano Lingnau [Paessler]