using System;

​

//dotnet add package Novell.Directory.Ldap.NETStandard --version 3.6.0

using Novell.Directory.Ldap•;

​

//https://stackoverflow.com/questions/49682644/asp-net-core-2-0-ldap-active-directory-authentication

​

public class Program

{

    public static void Main()

    {

        string domainName = "ldap.forumsys.com"; //LDAP://ldap.forumsys.com:389/cn=read-only-admin,dc=example,dc=com

        string username = "read-only-admin"; 

        string password = "password";

        Console.WriteLine(ValidateUser(domainName, username, password));

    }

public static bool ValidateUser(string domainName, string username, string password)

{

   string userDn = "cn=read-only-admin,dc=example,dc=com"; //$"{username}@{domainName}";

   try

   {

      using (var connection = new LdapConnection {SecureSocketLayer = false})

      {

         connection.Connect(domainName, LdapConnection.DefaultPort);

         connection.Bind(userDn, password);

         if (connection.Bound) {

            Console.WriteLine(connection.Connected);

            return true;

         }

      }

   }

   catch (Exception ex)

   {

      Console.WriteLine(ex.ToString());

   }

   return false;

}

}