[PRTG] Monitor website login

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#| _ \ _ \_   _/ __|
#|  _/   / | || (_ |
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#    NETWORK MONITOR
#-------------------
# Description: Monitors if a login on a website with a HTML login form works properly
# Parameters:
# -URL: The URL to the login form
# -Username: A valid username for the page
# -Password: The user's password
# -FormId: The ID of the login form
# -UsernameID: The CSS ID of the username field
# -PasswordID: The CSS ID of the password field
# -CheckString: A string element that only occurs if the login worked

# ------------------
# (c) 2015 Stephan Linke | Paessler AG
Param(
    [string]$url = "",
    [string]$logout = "",
    [string]$username="",
    [string]$password="",
    [int]$formId = "0",
    [string]$usernameId = "",
    [string]$passwordId = "",
    [string]$checkString = ""
)


$loginPage = (Invoke-WebRequest -Uri  "$url" -SessionVariable PRTG)

$LoginForm = $loginPage.Forms[$formId];
$LoginForm.Fields[$usernameId] = $username;
$LoginForm.Fields[$passwordId] = $password;

$result = Invoke-WebRequest -Uri ($url) -WebSession $PRTG -Method POST -Body $LoginForm.Fields
$response_code = $result.StatusCode
if($result.Content.Contains($checkString))
{
    Write-Host "$response_code:Login successful - '$($Checkstring)' found.";
    # Logout
    Invoke-WebRequest -Uri $logout -SessionVariable PRTG | Out-Null;
    Remove-Variable PRTG;
    exit 0;

}
else
{
    Write-Host "$response_code:Login failed or checkstring not found. Please check if the username/password combination as well as the  checkstring are correct!";
    # Logout
    Invoke-WebRequest -Uri $logout -SessionVariable PRTG | Out-Null;
    Remove-Variable PRTG;
    exit 1;
}