Understanding Kerberos in IronPDF

January 19, 2022

Updated June 1, 2025

How can I get UrlToPdf working with Kerberos authentication?

To use Kerberos authentication with IronPDF's UrlToPdf, you should set a username and password in the rendering settings. You can refer to the IronPDF documentation for more details: IronPdf.ChromeHttpLoginCredentials.

We recommend using System.Net.Http.HttpClient for downloading HTML content, which you can render afterward. This approach allows you to handle HTTP requests, including those requiring authentication, before IronPDF processes the content.

Here is an online guide on downloading pages with Kerberos: How does the System.Net.Http.HttpClient select authentication type?. This StackOverflow link provides a detailed discussion on implementing authentication using HttpClient.

To parse and ensure that all necessary assets within the HTML are downloaded, consider using the HTML Agility Pack. This .NET library helps in manipulating and querying HTML documents effectively.

// Example: Using HttpClient with Kerberos Authentication

// Import the necessary namespaces
using System;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;

namespace KerberosAuthenticationExample
{
    class Program
    {
        static async Task Main(string[] args)
        {
            // Create an instance of HttpClient
            HttpClientHandler handler = new HttpClientHandler
            {
                // Automatically use default network credentials
                UseDefaultCredentials = true // Enables Windows authentication (e.g., Kerberos)
            };

            using HttpClient httpClient = new HttpClient(handler);

            try
            {
                // Send a GET request to the desired URL
                HttpResponseMessage response = await httpClient.GetAsync("https://your-secure-url.com");

                // Ensure the request was successful
                response.EnsureSuccessStatusCode();

                // Read and display the response body
                string responseBody = await response.Content.ReadAsStringAsync();
                Console.WriteLine(responseBody);

                // If needed, render the HTML to PDF with IronPDF here
                // IronPdf.HtmlToPdf renderer = new IronPdf.HtmlToPdf();
                // renderer.RenderHtmlAsPdf(responseBody).SaveAs("output.pdf");
            }
            catch (HttpRequestException e)
            {
                // Handle any error responses from the server or connection issues
                Console.WriteLine("\nException Caught!");
                Console.WriteLine($"Message :{e.Message}");
            }
        }
    }
}

// Example: Using HttpClient with Kerberos Authentication

// Import the necessary namespaces
using System;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;

namespace KerberosAuthenticationExample
{
    class Program
    {
        static async Task Main(string[] args)
        {
            // Create an instance of HttpClient
            HttpClientHandler handler = new HttpClientHandler
            {
                // Automatically use default network credentials
                UseDefaultCredentials = true // Enables Windows authentication (e.g., Kerberos)
            };

            using HttpClient httpClient = new HttpClient(handler);

            try
            {
                // Send a GET request to the desired URL
                HttpResponseMessage response = await httpClient.GetAsync("https://your-secure-url.com");

                // Ensure the request was successful
                response.EnsureSuccessStatusCode();

                // Read and display the response body
                string responseBody = await response.Content.ReadAsStringAsync();
                Console.WriteLine(responseBody);

                // If needed, render the HTML to PDF with IronPDF here
                // IronPdf.HtmlToPdf renderer = new IronPdf.HtmlToPdf();
                // renderer.RenderHtmlAsPdf(responseBody).SaveAs("output.pdf");
            }
            catch (HttpRequestException e)
            {
                // Handle any error responses from the server or connection issues
                Console.WriteLine("\nException Caught!");
                Console.WriteLine($"Message :{e.Message}");
            }
        }
    }
}

' Example: Using HttpClient with Kerberos Authentication

' Import the necessary namespaces
Imports Microsoft.VisualBasic
Imports System
Imports System.Net
Imports System.Net.Http
Imports System.Net.Http.Headers
Imports System.Threading.Tasks

Namespace KerberosAuthenticationExample
	Friend Class Program
		Shared Async Function Main(ByVal args() As String) As Task
			' Create an instance of HttpClient
			Dim handler As New HttpClientHandler With {.UseDefaultCredentials = True}

			Using httpClient As New HttpClient(handler)
	
				Try
					' Send a GET request to the desired URL
					Dim response As HttpResponseMessage = Await httpClient.GetAsync("https://your-secure-url.com")
	
					' Ensure the request was successful
					response.EnsureSuccessStatusCode()
	
					' Read and display the response body
					Dim responseBody As String = Await response.Content.ReadAsStringAsync()
					Console.WriteLine(responseBody)
	
					' If needed, render the HTML to PDF with IronPDF here
					' IronPdf.HtmlToPdf renderer = new IronPdf.HtmlToPdf();
					' renderer.RenderHtmlAsPdf(responseBody).SaveAs("output.pdf");
				Catch e As HttpRequestException
					' Handle any error responses from the server or connection issues
					Console.WriteLine(vbLf & "Exception Caught!")
					Console.WriteLine($"Message :{e.Message}")
				End Try
			End Using
		End Function
	End Class
End Namespace

$vbLabelText $csharpLabel

Key points:

HttpClient and HttpClientHandler: Use HttpClientHandler with UseDefaultCredentials = true to allow Kerberos authentication using the current user's credentials.
Error Handling: Implement try-catch blocks to manage exceptions during HTTP requests.
HTML Rendering: Once the HTML is fetched, utilize IronPDF to render the content into a PDF if necessary.