How do I authenticate a WebClient request?

Question

I am making a call to a page on my site using webclient. I'm trying to get the result of the webpage put into a pdf so I am trying to get a string representation of the rendered page. The problem is that the request is not authenticated so all I get is a login screen. I have sent the UseDefaultCredentials property to true but I still get the same result. Below is a portion of my code:

 WebClient webClient = new WebClient();
 webClient.Encoding = Encoding.UTF8;

 webClient.UseDefaultCredentials = true;
 return Encoding.UTF8.GetString(webClient.UploadValues(link, "POST",form));

Found very nice solution [here](https://www.codeproject.com/Articles/624624/Using-a-Cookie-Aware-WebClient-to-Persist-Authenti) — sairfan, May 20 '18 at 01:47

score 113 · Answer 1 · edited Feb 10 '20 at 19:08

113

You need to give the WebClient object the credentials. Something like this...

 WebClient client = new WebClient();
 client.Credentials = new NetworkCredential("username", "password");

edited Feb 10 '20 at 19:08

Gabriel Luci

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answered Dec 10 '09 at 20:15

Ryan Alford

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This worked. Note that I didn't have to set UseDefaultCredentials to true. – NightShovel Mar 09 '15 at 22:50
1

Where you passed website address – Jun 27 '15 at 04:48
the package is having difficulties with the WebClient , I cannot right click to resolve as there is no option to do this ...please help – Joeysonic Sep 02 '19 at 10:51
What if the credentials are correct but this results in a `401 Unauthorized`? – Jonathan May 06 '20 at 09:46
which dependency should i use to work with NetworkCredential? – Asim Jan 21 '21 at 03:33

score 2 · Accepted Answer · answered Dec 10 '09 at 20:17

2

What kind of authentication are you using? If it's Forms authentication, then at best, you'll have to find the .ASPXAUTH cookie and pass it in the WebClient request.

At worst, it won't work.

answered Dec 10 '09 at 20:17

John Saunders

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Then you need `WebClient` to behave like a browser woould have behaved. You need to send the cookie. – John Saunders Dec 10 '09 at 20:26
Um, not sure how I would do that. Any suggestions? Thanks. – smartdirt Dec 10 '09 at 20:33
Get the cookie using Request.Cookies, then send it by using HttpWebRequest.Cookies. You won;t be able to use WebClient. – John Saunders Dec 10 '09 at 21:31
@black I agree. – John Saunders Oct 11 '18 at 21:18

score 0 · Answer 3 · edited Sep 14 '15 at 16:50

0

Public Function getWeb(ByRef sURL As String) As String
    Dim myWebClient As New System.Net.WebClient()

    Try
        Dim myCredentialCache As New System.Net.CredentialCache()
        Dim myURI As New Uri(sURL)
        myCredentialCache.Add(myURI, "ntlm", System.Net.CredentialCache.DefaultNetworkCredentials)
        myWebClient.Encoding = System.Text.Encoding.UTF8
        myWebClient.Credentials = myCredentialCache
        Return myWebClient.DownloadString(myURI)
    Catch ex As Exception
        Return "Exception " & ex.ToString()
    End Try
End Function

edited Sep 14 '15 at 16:50

Druid

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answered Nov 05 '11 at 15:23

Rouletabille

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This is not C#. – Luca Ziegler Sep 08 '16 at 12:08
1

Great, thanks. Its VB.Net, you can convert this to C# here: http://converter.telerik.com/ – haroonxml Mar 09 '17 at 17:08
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It also has poor exception handling. It hides the exception. – John Saunders Sep 23 '18 at 13:29
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You are using a code converter? Are you kidding me? Why not writing assembler in css using a converter? – Jonathan May 06 '20 at 09:47

score -1 · Answer 4 · answered Jun 29 '20 at 11:16

This helped me to call API that was using cookie authentication. I have passed authorization in header like this:

request.Headers.Set("Authorization", Utility.Helper.ReadCookie("AuthCookie"));

complete code:

// utility method to read the cookie value:
        public static string ReadCookie(string cookieName)
        {
            var cookies = HttpContext.Current.Request.Cookies;
            var cookie = cookies.Get(cookieName);
            if (cookie != null)
                return cookie.Value;
            return null;
        }

// using statements where you are creating your webclient
using System.Web.Script.Serialization;
using System.Net;
using System.IO;

// WebClient:

var requestUrl = "<API_url>";
var postRequest = new ClassRoom { name = "kushal seth" };

using (var webClient = new WebClient()) {
      JavaScriptSerializer serializer = new JavaScriptSerializer();
      byte[] requestData = Encoding.ASCII.GetBytes(serializer.Serialize(postRequest));
      HttpWebRequest request = WebRequest.Create(requestUrl) as HttpWebRequest;
      request.Method = "POST";
      request.ContentType = "application/json";                        
      request.ContentLength = requestData.Length;
      request.ContentType = "application/json";
      request.Expect = "application/json";
      request.Headers.Set("Authorization", Utility.Helper.ReadCookie("AuthCookie"));
      request.GetRequestStream().Write(requestData, 0, requestData.Length);

      using (var response = (HttpWebResponse)request.GetResponse()) {
         var reader = new StreamReader(response.GetResponseStream());
         var objText = reader.ReadToEnd(); // objText will have the value
      }
}

It's a working code. AuthCookie will be your cookie – KushalSeth Jun 24 '21 at 21:18 — KushalSeth, Jun 24 '21 at 21:18

How do I authenticate a WebClient request?

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