403 Forbidden Error while trying to access External SharePoint site in SP 2010

Question

I am trying to access external Claims based SP site and trying to download the file from a doc library.
I am receiving the 403 Forbidden error when executing the code.
I am using SP 2010 and Client Object Model.
PFB the code I am running.
using (SPCOM.ClientContext clientContext = ClaimClientContext.GetAuthenticatedContext(siteURL))
if (clientContext != null)
clientContext.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;
clientContext.Load(clientContext.Web);
clientContext.ExecuteQuery();
SPCOM.Web web = clientContext.Web;
clientContext.Load(web);
clientContext.ExecuteQuery();
using (SPCOM.FileInformation fInfo = SPCOM.File.OpenBinaryDirect(clientContext, item["FileRef"].ToString()))
string fileName = (string)item["FileRef"];
fileName = string.Concat(SaveLocation, fileName.Substring(fileName.LastIndexOf("/") + 1));
//now save it
using (System.IO.FileStream outPutFile = System.IO.File.OpenWrite(fileName))
fInfo.Stream.CopyTo(outPutFile);
fInfo.Stream.Close();
I suspect the OpenBinaryDirect method ,
I am also using Cookie based authentication I guess PFB the code for that.
public static ClientContext GetAuthenticatedContext(string targetSiteUrl)
return (GetAuthenticatedContext(targetSiteUrl, 0, 0));
/// <summary>
/// This method will return a ClientContext object with the authentication cookie set.
/// The ClientContext should be disposed of as any other IDisposable
/// </summary>
/// <param name="targetSiteUrl"></param>
/// <returns></returns>
public static ClientContext GetAuthenticatedContext(string targetSiteUrl, int popUpWidth, int popUpHeight)
CookieCollection cookies = null;
cookies = ClaimClientContext.GetAuthenticatedCookies(targetSiteUrl, popUpWidth, popUpHeight);
if (cookies == null) return null;
ClientContext context = new ClientContext(targetSiteUrl);
try
context.ExecutingWebRequest += delegate(object sender, WebRequestEventArgs e)
e.WebRequestExecutor.WebRequest.CookieContainer = new CookieContainer();
foreach (Cookie cookie in cookies)
e.WebRequestExecutor.WebRequest.CookieContainer.Add(cookie);
catch
if (context != null) context.Dispose();
throw;
return context;
If anyone has an idea of why is this happening, pls help me. 
Thanks,
K.V.N.PAVAN

Answer 1

Hi,
Please try to add following line of code before you initialize cookie container.
e.WebRequestExecutor.WebRequest.UserAgent = “Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)”;
http://razirais.wordpress.com/2011/05/19/how-to-fix-sharepoint-online-403-forbidden-error-while-downloading-files-using-client-object-model/
Or change the following line of code
clientContext.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;
to
clientContext.Credentials=new NetworkCredential("Username", "Passworkd", "Domain");
Thanks,
Dennis Guo
TechNet Community Support
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Dennis Guo
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