class credenziali : Microsoft.Reporting.WebForms.IReportServerCredentials
    {
        public bool GetFormsCredentials(out System.Net.Cookie authCookie, out string userName, out string password, out string authority)
        {
            userName = HttpContext.Current.User.Identity.Name;
            authCookie = FormsAuthentication.GetAuthCookie();
        }        
        
        public System.Net.ICredentials NetworkCredentials
        {
            get { return new System.Net.NetworkCredential("teo", "teo"); }
        }


etc...