Validate Login User with AD/LDAP authentication(Login Page)

Validating users against Active Directory/ LDAP. Also many organisation have multiple domains and same application needs to validate accross all domain.

This code can be used in SharePoint custom Login form for user Validation for Claim based authentication or Form Based Authentication.




Reference Added :

using System.Runtime.InteropServices; 

COMException : The exception that is thrown when an unrecognized HRESULT is returned from a COM method call for more simplified error response from LDAP Error: Unknown error (0x80005000).

using System.DirectoryServices;

Below is the code sniplet

  using (DirectoryEntry entry = new DirectoryEntry())
        {
            entry.Username = "DOMAIN\\LOGINNAME";
            entry.Password = "PASSWORD";
            DirectorySearcher searcher = new DirectorySearcher(entry);
            searcher.Filter = "(objectclass=user)";
            try
            {
                searcher.FindOne();
                {
                    //Add Your Code if user Found..
                }
            }
            catch (COMException ex)
            {
                if (ex.ErrorCode == -2147023570)
                {
                    ex.Message.ToString();
                    // Login or password is incorrect 
                }
            }
        }

ErrorCode : -2147023570 suggest the Username or password is not correctly entered.

post your questions, comments or suggestion.