Making a web request to a web page which requires windows authentication

Question

I am trying to make a request to a web page using WebRequest class in .net. The url that I am trying to read requires Windows Authentication due to which I get an unauthorised exception. How can I pass a windows credentials to this request so that it can authenticate.

HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create( "http://myapp/home.aspx" );

request.Method = "GET";
request.UseDefaultCredentials = false;
request.PreAuthenticate = true;
request.Credentials = new NetworkCredential( "username", "password", "domain" );

HttpWebResponse response = (HttpWebResponse)request.GetResponse(); // Raises Unauthorized Exception

this.Response.Write( response.StatusCode );

The above code returns the following error.

System.Net.WebException: The remote server returned an error: (401) Unauthorized.

I noticed one thing while checking the exception details is that the url that I am trying to access is redirecting to a different url which is prompting me to provide the NT login details. I believe that the credentials should get forwarded to this url as well. But apparently it is not happening.

This might help: msdn.microsoft.com/en-us/library/ff647405.aspx — NullUserException
– NullUserException, Commented Aug 25, 2010 at 5:12
Thanks, setting PreAuthenticate to true helped solve my problem. — Michael
– Michael, Commented Jun 18, 2012 at 1:31

N. Taylor Mullen · Accepted Answer · 2013-08-02 17:58:11Z

53

You should use Credentials property to pass the windows credentials to the web service.

If you wish to pass current windows user's credentials to the service then

request.Credentials = CredentialCache.DefaultCredentials;

should do the trick. Otherwise use NetworkCredential as follows:

request.Credentials = new NetworkCredential(user, pwd, domain);

edited Aug 2, 2013 at 17:58

N. Taylor Mullen

18.3k6 gold badges51 silver badges73 bronze badges

answered Aug 25, 2010 at 5:18

VinayC

49.6k7 gold badges64 silver badges74 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Hemanshu Bhojak Over a year ago

As you can see in the code which I have posted, I am using the NetworkCredential class to pass my windows login. But even that is not working.

VinayC Over a year ago

Did you put the code later - I don't recall seeing it. Regardless, 401 error means credentials can be wrong or it can also mean that credentials are right but that user does not have access to that URL. I will suggest that you check your service url from browser. If it works from there then it should work with WebRequest as well as.

Hemanshu Bhojak Over a year ago

I edited the post and included the code. Also, I am able to access the url in the browser with the credentials but not able to do the same using WebRequest.

VinayC Over a year ago

Try with request.PreAuthenticate = false; Reasoning is that server is throwing 401 as a challenge response and WebRequest would not respond to the challenge unless this property is false.

VinayC Over a year ago

Tough luck! Just last suggestion - use tool such as Fiddler (www.fiddler2.com) and compare request-response chain from browser (to service) with the same from WebRequest. As you have said that service works from browser, by comparing request-response, you should get the idea where the problem is.

|

Vitaliy Ulantikov · Accepted Answer · 2011-10-24 09:21:28Z

14

For authenticating to WebService, use DefaultNetworkCredentials instead of DefaultCredentials:

request.Credentials = CredentialCache.DefaultNetworkCredentials;

edited Oct 24, 2011 at 9:21

answered Oct 24, 2011 at 9:14

Vitaliy Ulantikov

10.6k3 gold badges67 silver badges56 bronze badges

2 Comments

empz Over a year ago

This fixed a problem I've been trying to fix for a week. Thank you!

AFract Over a year ago

I'm wondering if it could help to fix my current issue : stackoverflow.com/questions/67335532/… ? I read contradictory things regarding differences between each of them. I'll try ASAP.

Hemanshu Bhojak · Accepted Answer · 2010-08-31 05:18:24Z

10

I am trying to access a link A passing the windows credentials. Link A then redirects me to link B automatically but does not pass the windows credentials which I had supplied. Hence the error. I did request.AutoRedirect = false, and looped through every time I get location in the header i.e. I do my redirects manually each time passing the windows credentials.

This worked for me :)

answered Aug 31, 2010 at 5:18

Hemanshu Bhojak

17.3k19 gold badges51 silver badges64 bronze badges

Comments

Rob Bowman · Accepted Answer · 2016-03-15 10:34:40Z

7

Using VS2015, request.UseDefaultCredentials = true; works for me!

answered Mar 15, 2016 at 10:34

Rob Bowman

8,88928 gold badges125 silver badges247 bronze badges

Collectives™ on Stack Overflow

Making a web request to a web page which requires windows authentication

4 Answers 4

7 Comments

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

7 Comments

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related